Crossrail: A technical guide for developers |
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Contents 1
Introduc on
05
2
General Informa on
06
3
Se lement
08
4
Noise and Vibra on
09
5
Engagement with Crossrail
11
6
Crossrail’s Standard Condi ons
13
Appendix A
Predic on of Ground Movements and Associated Building Damage due to Bored Tunnel
14
Appendix B
Example Calcula on of Tunnel se lement and Associated Building Strains
29
Appendix C
Noise and Vibra on Assessment Summary
43
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| Crossrail: A technical guide for developers
Varies
Alignment adjustment zone
Exclusion zone
ŽŶƐƚƌƵĐƟŽŶ tolerance zone
Running tunnel 6.2m
Figure 1 Chelsea Hackney Line Exclusion and Tolerance Zones
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1
IntroducƟon
1.1
Under the provisions of the June 2008 Chelsea Hackney Line safeguarding Direc ons, issued by the Secretary of State for Transport, Local Planning Authori es (LPAs) are required to consult Crossrail Limited (CRL) before determining certain planning applica ons which fall within the limits of land subject to consulta on, as defined by the Safeguarding Direc ons.
1.2
The purpose of this process is to ensure that the future construc on of the Chelsea Hackney Line (CHL) is not prejudiced by any other new development and that new development itself is not adversely affected (to an unacceptable degree) by the construc on of CHL.
1.3
The applicant/developer must be able to demonstrate to CRL that, for example, the founda ons of new development proposals do not obstruct the route of the CHL tunnels or adversely impact on the tunnel design or other infrastructure. New developments therefore should be designed to mi gate the possible effects on new development caused by the construc on and opera on of CHL, such as se lement or opera onal noise and vibra on and avoid incurring CRL any addi onal costs.
1.4
As part of the consulta on process, CRL can:a)
recommend that the Local Planning Authority place condi ons on a planning permission which must be complied with/discharged before construc on of the approved development can commence on site, or;
b) recommend that the Local Planning Authority refuse the applica on. 1.5
In order to assist developers to design buildings to meet these objec ves, and to avoid the possibility of a recommenda on of refusal being made to the LPA, key informa on about CHL design criteria is set out in this document.
PLEASE NOTE ANY REFERENCE TO “CROSSRAIL” IN THE TECHNICAL SECTIONS OF THE DOCUMENT SHOULD BE READ AS APPLYING TO THE CROSSRAIL 2/CHELSEA HACKNEY LINE SCHEME.
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2
General InformaƟon
2.1
Tunnel size The outside diameter of the CHL running tunnels should be taken as 7.0m (see Figure 1 on page 4). Note that some example calcula ons in this document use 6.6m, however 7.0m should be used in developer’s calcula ons. The diameter of sta on and other tunnels varies and in most cases has not yet been established. The developer should ask CRL’s Safeguarding Manager for further advice on this issue.
2.2
CHL box structures CRL will also be construc ng buried box structures at some loca ons. These include deep box sha s, cket halls, basements and box sta ons. Developers must consider the impact of their proposals on these box structures in a similar manner to CHL tunnels. The developer should seek advice from CRL’s Safeguarding Manager regarding the par cular constraints imposed by these structures.
2.3
Tunnel exclusion and construc on tolerance zones This document is only applicable to developments that occur before the CHL tunnels are constructed. If a developer has entered into a separate development agreement with CRL, then the terms contained within that development agreement take precedence over this document. The proposed loca on of CHL tunnels or other infrastructure will be provided by CRL’s Safeguarding Manager. It should be noted, however, that the loca on of most of the CHL tunnels and other infrastructure has not yet been determined. These could be in any posi on both horizontally and ver cally within the safeguarding limits, par cularly at loca ons of sta ons and ven la on sha s. In loca ons where firm posi ons for the CHL tunnels can be provided, the following will apply. Developers should note that an exclusion zone exists around the tunnels (see Figure 1 on page 4). Founda ons for permanent and temporary works may not come closer than 3m horizontally and 6m above the as built tunnels. However, for developments that are planned to be built before CHL is constructed, a further 0.5m tunnel construc on tolerance must be added to the exclusion zone dimensions (giving a total exclusion zone of 3.5m horizontally and 6.5m above the tunnels). The developer must also make adequate allowance for the construc on tolerance of the proposed development founda ons in determining their proximity to the Crossrail tunnels. CRL is also retaining the flexibility to move the tunnels 3m in either direc on horizontally and 4.5m ver cally*. This is referred to as the alignment adjustment zone and the design of any new development should take account of this possible devia on. The alignment adjustment zone is required to retain flexibility to amend the CHL alignment, within the safeguarding limits to avoid poten al obstruc ons or other alignment constraints as the tunnel design evolves. Figure 1 on page 4 iden fies these zones. In certain loca ons, where the alignment is constrained by other factors, the full tolerance may not be required. In these circumstances, CRL’s Safeguarding Manager will advise the developer accordingly. In all other cases, the exclusion and adjustment zones should be added to indicate the total area that the founda ons for new development should avoid, i.e. a minimum of 11.0m ver cally and 6.5m horizontally.
* In a specific area on the alignment this measurement is greater – Please consult with Crossrail’s Safeguarding Manager
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2.4
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Loads from development founda ons Development founda ons must be designed so that stresses induced in the future tunnel linings do not exceed acceptable levels. In general, this will be achieved if the overall loading imposed on the tunnels: a) does not exceed the exis ng ground overburden plus the loading from any exis ng development (as would be the case for redevelopment of an exis ng site), or; b) does not exceed the exis ng ground overburden plus 50kN/m2 imposed at ground level over the footprint of the development (as would be the case in development of a vacant site). The CHL tunnels have been designed to account for exis ng loads.
2.5
Once CHL is constructed the developer will be required to demonstrate that the impact of a construc on on CHL is acceptable and to cover any costs incurred by CRL in rela on to assessment of engineers submissions, instrumenta on, monitoring, con ngency plans and a endance at mee ngs.
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3
SeƩlement
3.1
Construc on of the Crossrail tunnels will cause se lement of the ground above. The founda ons of the new development should therefore be designed so that damage to the development from this se lement does not exceed acceptable levels.
3.2
The method by which CRL calculates se lement effect is described in Appendix A. The developer may wish to use the same method, although CRL cannot accept any responsibility for its use. CRL an cipates that the percentage face losses from tunnelling will be 1.0 per cent (was 1.7 per cent) (approximately) for running tunnels and 1.5 per cent (was 2.0 per cent) (approximately) for sta on tunnels.
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4
Noise and VibraƟon
4.1
Opera on of Crossrail trains may cause vibra on and re-radiated noise to be transmi ed from the tunnels to the founda ons of the development. Therefore, founda ons should be designed so that the level of noise generated within the building by this vibra on remains within limits acceptable to the developer without CRL having to install mi ga on measures within the tunnel.
4.2
Crossrail Line 1 is subject to a range of requirements including Undertakings and Assurances given during the Parliamentary passage of the Crossrail Bill through Parliament. There are also legal agreements which determine the degree of provision for controlling vibra on and ground borne noise in the opera on of Crossrail vehicles. These requirements apply in some respects system-wide although the design limits involved are specific to the class of use of the building (i.e. a general limit for residen al development). Addi onally, there are locally specific requirements for individual buildings.
4.3
In most areas where new development is proposed, it will either be planned to take place on the site of a previous building which will have already been the subject of a design limit for vibra on and groundborne noise according to its use, or be situated between other exis ng buildings to which a limit applies.
4.4
In the case of redevelopment of a site previously occupied by a building subject to an exis ng limit for vibra on and groundborne noise it does not automa cally follow that the likely level of vibra on and groundborne noise in the new building will meet Crossrail’s requirements, because the founda ons may differ in ways which increase the transmission of vibra on and groundborne noise into the building. Likewise, the proximity of an exis ng building to a newly developed site does not automa cally ensure that the limits will not be exceeded in the proposed new buildings, because of differences in founda ons, local geotechnical condi ons, differences in train speeds and other parameters.
4.5
The system-wide, use-specific limits to which CRL is subject are set out in Informa on Paper D10. In summary, the requirement is that the nominated undertaker will be required to design the permanent track support system so that the level of groundborne noise near the centre of any noise-sensi ve room is predicted in all reasonably foreseeable circumstances not to exceed the levels in Table 1 (page 10). Reasonable endeavours are required to adopt mi ga on measures that will further reduce any adverse environmental impacts to any residen al property in which the level of groundborne noise arising from the opera on of the Crossrail passenger service near the centre of any noise-sensi ve room is predicted to equal or exceed 35dB LAmax,S.
4.6
The nominated undertaker will also be required to design the permanent track system, in accordance with the guidance in the 1992 version of Bri sh Standard 6472 “Guide to evalua on of human exposure to vibra on in buildings (1 Hz to 80 Hz)”, so that opera onal vibra on arising from it at buildings iden fied in Table 1, expressed as vibra on dose value (VDV), is predicted in all reasonably foreseeable circumstances not to exceed the levels presented in Table 2 (page 10). Note that since the 1992 version is used the VDV values use weigh ng Wg for z-axis vibra on for guidance only. For further informa on, contact the CRL Third Party Development Manager.
4.7
The levels of vibra on at the tunnel wall caused by the passage of a single train travelling at 100 km/h and at 80 km/h are presented in Tables 1 and 2 in Appendix C. The same data are also presented in graphic format in Figures 1 to 4 in Appendix C. It should be noted that these data are based on conserva ve assump ons of track s ffness and should be used for guidance only. For further informa on, contact the CRL Third Party Development Manager.
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4.8
With regard to vibra on, it is normally the case that where groundborne noise criteria are sa sfied, vibra on criteria are also sa sfied. The data in Appendix C relate to vibra on down to the 20Hz 1/3 octave band. In cases where a development involves par cular sensi vity to vibra on predic ons down to 1Hz may be required and further informa on should be sought from the CRL Safeguarding Manager.
Table 1: Construc on1 and Opera onal Groundborne Noise Criteria Building
Level/Measure
Residen al buildings
40dB LAmax,S
Offices2
40dB LAmax,S
Hotels
2
40dB LAmax,S
Theatres
25dB LAmax,S
Large Auditoria/Concert Halls
25dB LAmax,S
Sound recording studios
30dB LAmax,S
Places of mee ng for religious worship3
35dB LAmax,S
Courts, lecture theatres
35dB LAmax,S
Small Auditoria/halls
35dB LAmax,S
Hospitals, laboratories
A40dB LA
Libraries
40dB LAmax,S
max,S
Notes 1. Excluding the groundborne noise from the passage of the tunnel boring machine (TBM). 2. Significance criteria not included in the Scope and Methodology set out in Appendix A2, Vol. 5 of the Crossrail Environmental Statement, added here for clarifica on. 3. Meaning a place the principal use of which is for people to come together as a congrega on to worship God or do reverence to a deity.
Table 2: Construc on and Opera onal Vibra on Criteria In the Absence of Appreciable ExisƟng Levels of VibraƟon
Appreciable ExisƟng Levels of VibraƟon1, 2
VDV ms-1.75 Day me (07:00 – 23:00)
VDV ms-1.75 Night- me (23:00 – 07:00)
% Increase in VDV
0.31
0.18
40
Notes: 1. Highest impact category used, day me or night- me. 2. There is an appreciable exis ng level of vibra on where day me and night- me vibra on dose values (VDVs) exceed 0.22 ms-1.75 and 0.13 ms-1.75 respec vely.
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5
Engagement with Crossrail
5.1
The developer is advised to consult CRL prior to submission for Planning, to maximise opportunity for understanding and considera on of project interface constraints and opportuni es, and the condi ons which Crossrail may seek to impose on development.
5.2
Crossrail’s principal points of contact for Planning ma ers are Roger Tuffley: rogertuffl
[email protected]; telephone 0203 229 9194 David Taylor:
[email protected]; telephone 0203 229 9223
5.3
Alterna vely Crossrail can be contacted through its Helpdesk (contact number: 08345 602 3813). The developer may then request consulta on with Crossrail’s Third Safeguarding Manager.
5.4
Crossrail expect developers to submit evidence demonstra ng their compliance with the requirements of this document and any relevant planning condi ons. Suitable evidence will enable Crossrail to issue a le er of no objec on to the planning authority endorsing acceptance for planning purposes.
5.5
Crossrail reserves the right to charge developers for me and resource u lised in assessing development proposals, par cularly where specialist engineering resources have to be commissioned to advise.
5.6
Crossrail would prefer to see such evidence contained within structured format such as a Conceptual Design Submission (CDS). The following sub headings are offered as a guide to the contents of the CDS
a)
Execu ve Summary
b)
Introduc on, se ng out objec ves: • • •
c)
That the future construc on of Crossrail is not prejudiced by the proposed building; That the building itself is not adversely affected to an unacceptable degree by the construc on of Crossrail; Compliance with terms of a Development Agreement (if applicable).
Overview, outlining: • • •
The nature of the development; Proximity in respect of Crossrail; Assump ons for tunnel diameter, clearance requirements and exclusion zones, volume loss and noise & vibra on assessment and other criteria as set out in the this document.
d)
The Par es, including contacts, roles and responsibili es
e)
Outline Project Programme including key milestones dates (accuracy commensurate with knowledge at planning stage of development)
f)
Summary of Assump ons on exis ng site condi ons, including compiled assump ons on ground condi ons, groundwater, ground contamina on (if appropriate). Details substan ated by desk top assessment or intrusive surveys as appropriate, supplied by the developers design representa ves.
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g)
Effects of Proposed Construc on on Crossrail, to include:• • •
h)
Summary of predicted se lements analysis during development construc on phases (calcula ons to be appended as necessary); Summary of surcharge loading changes; Summary of any predicted construc on interface impacts and evidence that these are manageable and compliant with CDS.
Effects of Crossrail on Proposed Development, to include • •
Summary of predicted se lement damage assessment (using method in this document for shallow founda ons, if applicable – calcula ons to be appended); Summary of noise & vibra on assessment (using method prescribed).
i)
Standards and References
j)
Appendices – (drawings & calcula ons demonstra ng compliance)
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Crossrail’s Standard CondiƟons
6.1
Crossrail have the right to be consulted on all development occurring within the Safeguarding Limits. Typically such development is referred to Crossrail by the Local Planning Authority for comment. Typically the following condi ons are applied in order to protect the Crossrail Project. Crossrail condiƟon for foundaƟon design, noise, vibraƟon and seƩlement C1
None of the development hereby permi ed shall be commenced un l detailed design and construc on method statements for all of the ground floor structures, founda ons and basements and for any other structures below ground level, including piling (temporary and permanent), have been submi ed to and approved in wri ng by the Local Planning Authority which:(i)
Accommodate the proposed loca on and of the Crossrail structures including tunnels, sha s and temporary works,
(ii)
Accommodate ground movement arising from the construc on thereof,
(iii) Mi gate the effects of noise and vibra on arising from the opera on of the Crossrail railway within the tunnels and other structures. (iv) Mi gate the effects on Crossrail, of ground movement arising from development The development shall be carried out in all respects in accordance with the approved design and method statements. All structures and works comprised within the development hereby permi ed which are required by paragraphs C1(i), (ii), (iii) and (iv) of this condi on shall be completed, in their en rety, before any part of the building[s] hereby permi ed [is][are] occupied. InformaƟve: Crossrail Ltd has indicated its preparedness to provide guidelines in rela on to the proposed loca on of the Chelsea Hackney Line structures and tunnels, ground movement arising from the construc on of the tunnels and noise and vibra on arising from the use of the tunnels. Applicants are encouraged to discuss these guidelines with the Chelsea Hackney Line engineer in the course of preparing detailed design and method statements.
Appendix A Predic on of Ground Movements and Associated Building Damage due to Bored Tunnelling
Appendix A
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1
IntroducƟon
1.1
The purpose of this document is to present a method of assessing the poten al damage to masonry buildings due to tunnelling.
1.2
In assessing building damage due to tunnel construc on, the Crossrail project team will use a staged process, with increasing detail included at each phase of assessment, to eliminate buildings and structures from further considera on. The calcula on procedure described in this document covers the phase 2 assessment of se lements and building damage due to tunnel construc on. A simplified analysis for a plane sec on is considered with all movements occurring in that plane, i.e. two dimensional plane strain condi ons are assumed. More complex three dimensional cases, as would exist at sta on and sha loca ons, are not covered. However, for the majority of cases where only running tunnels are present, the two dimensional idealisa on will be adequate.
1.3
The method adopted essen ally uses an empirical procedure (based on field measurements) to determine ground movements at founda on level, assuming ‘greenfield’ condi ons, i.e. ignoring the presence of the building and the ground above founda on level. It is then assumed that the building follows the ground (i.e. it has negligible s ffness) and hence the distor ons and consequently the strains in the building can be calculated. A risk or damage assessment is made using the criteria defined by Burland and Wroth (1974) and the classifica on presented by Burland et al (1977).
1.4
The method of predic ng ground movements is applicable to all bored horizontal tunnels (at inclina ons of up to 30° to the horizontal). The procedure for calcula ng building strains is only relevant to buildings on shallow founda ons (which may include a basement), and the method of assessment of poten al damage is only applicable to masonry structures.
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Appendix A
2
Procedure for PredicƟng Movements due to Tunnelling
2.1
Ver cal se lement Ini ally, the case of a single tunnel will be considered. The procedure adopted generally follows that outlined by O’Reilly and New (1982) and extended by New and O’Reilly (1991). Figure 1 below shows a tunnel of excavated diameter D with its axis at depth z below ground level (it can be assumed that this procedure is also applicable to non-circular tunnels). In the context of predic ng se lement damage to buildings, ground level is taken as founda on level. Construc on of the tunnel results in ground movements with a se lement trough developing above the tunnel. Analysis of a considerable number of case records has demonstrated that the se lement trough is well described by a Gaussian distribu on curve as:
(1) where
Sv
is the ver cal se lement,
Smax is the maximum ver cal se lement on the tunnel centre line, y
is the horizontal distance from the centre line, and
i
is the trough width parameter and is the horizontal distance to the point of inflexion on the se lement trough.
y i
Original ground level
S max
z
Ground level following tunnel construc on
D
Figure 1 Cross sec on showing tunnel geometry
Appendix A
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The volume of the se lement trough (per metre length of tunnel), vs, can be evaluated by integra ng Equa on 1 to give:
(2) The volume loss is usually expressed as a frac on, vl, of the excavated area of the tunnel, ie for a circular tunnel:
(3)
For non-circular or inclined tunnels, the area of the tunnel intersected by a ver cal plane should replace the term π D 2 / 4 in Equa on 3. O’Reilly and New (1982) collated data from many tunnel construc on projects and were able to show that for tunnels in London Clay vl is unlikely to be in the range one to three per cent. The selec on of appropriate values of volume loss depends on the construc on method envisaged and on the ground condi ons. O’Reilly and New also correlated data of observed se lement troughs to show that the trough width parameter i was a reasonable linear func on of the depth Z and independent of tunnel construc on method. It can be assumed that the simple approximate form (4)
can be adopted. Values of K for tunnels in clay (cohesive soil) and sands or gravels (granular soils) are taken as approximately 0.5 and 0.25 respec vely. The choice of an appropriate value of K will o en require some judgement, since it depends on whether the ground between the tunnel and the founda on being considered is primarily cohesive or granular. Equa ons 1 to 4 can be combined to give the predicted ver cal se lements as;
(5)
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2.2
Horizontal movements
Appendix A
y Sh Sv
z
Figure 2 Surface movement above a tunnel
Building damage can also result from horizontal tensile strains, and therefore a predic on of horizontal movement is required. There are few case histories where horizontal movements have been measured, but the data that exist show reasonable agreement with the assump on of O’Reilly and New (1982) that the resultant vectors of ground movement are directed towards the tunnel axis. As shown on Figure 2 above, the vector of ground movement has ver cal and horizontal components Sv and Sh respec vely. Assuming that the vector is directed towards the tunnel axis, then:
(6)
which allows a simple assessment of horizontal movement. Equa on 6 can be rewri en as:
(7)
Appendix A
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Horizontal strain can be determined by differen a ng Equa on 7 with respect to y, which gives:
i.e: (8)
It is relevant to note that the ver cal strain is given by:
i.e: (9)
Since a constant volume (i.e. undrained) condi on is implied, which is generally found during tunnel construc on in clay. For tunnels in sands or gravels, some bulking (dila on) of the ground might be expected, and Equa ons 6 to 8 are likely to over predict horizontal movements and strains. Figure 3 below shows the rela on between the ver cal se lement trough, the horizontal movements and horizontal strains occurring at ground level. In the region, i >y> –i, horizontal strains are comprehensive. At the points of inflexion y =±i, the horizontal movements are greatest and the horizontal strain is zero. For i < y < –i, the horizontal strains are tensile.
Movement towards tunnel Sh
h
y
-y i
-i S
Settlement, compressive strain Figure 3 Distribu on of ver cal and horizontal movements and horizontal strains above a tunnel
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2.3
Mul ple tunnels
Appendix A
It is assumed that superposi on can be applied using all the above equa ons. It is usually simplest to calculate movements and strains rela ve to a fixed reference point at the ground surface, and o en the edge of a building is chosen. Such a case is illustrated on Figure 4 below.
y´
Building
L2
L1
Z1
Z2
Tunnel 1
Tunnel 2
Figure 4 Cross sec on showing typical geometry with twin tunnels passing beneath a building
For Tunnel 1, Equa ons 1 to 9 can all be used as required by subs tu ng z = z1 and y = y´ + L1 in the equa ons. Similarly, for Tunnel 2, z = z2 and y = y´ – L2 should be subs tuted. Total movements and strains are then found by summa on, for example:
i.e:
(10)
Appendix A
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Different tunnel diameters or volume loss parameters can be easily taken into account. The points of inflexion of the combined se lement trough are required for the assessment of building damage. For the se lement trough above a single tunnel, the slope is given by:
(11) and the curvature is given by:
(12) The curvature of the se lement profile due to mul ple tunnels can be determined by summa on of the curvatures due to individual tunnels (a change in the sign of curvature occurs at a point of inflexion). 2.4
Alterna ve methods of calcula ng ground movements due to tunnel excava on such as New and Bowers (1994) may be appropriate par cularly for cases where structures are within one diameter of any tunnel.
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3
Building Strains
3.1
Relevant building dimensions
Appendix A
It is necessary to define the relevant height and length of the building. A typical situa on that might exist is shown on Figure 5. The height is taken as the height from founda on level to the eaves. It is assumed that a building can be considered separately either side of a point of inflexion, i.e. points of inflexion of the surface se lement profile will be used to divide the building. For example, building lengths Lh and Ls should be used respec vely when assessing building damage in the hogging and sagging zones. The length of building will not be considered beyond the limit of the se lement trough, taken as, 2.5i, i.e. where Sv / Smax = 0.044. In any calcula on of building strain, the building span length is required and is defined as the length of building in a hogging or sagging zone (i.e. Lh or Ls as shown on Figure 5) and limited by a point of inflexion or extent of se lement trough as described.
Hogging zone
H
Sagging zone
Building
Lh
Ls i
2.5i
Prac cal limit of se lement trough
Point of inflec on
Figure 5 General case of a building affected by a tunnel se lement trough
Tunnel centre line
Appendix A
3.2
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Strains due to ground se lement Ground movements will usually generate tensile strains in buildings which can lead to cracking and general damage. The problem of se lement damage to buildings was considered at length by Burland and Wroth (1974). They treated a building as an idealised beam with span L and height H deforming under a central point load to give a maximum deflec on ∆. They argued that, for the por on of the building in the hogging mode, the restraining effect of the founda ons would, in effect, lower the neutral axis which could therefore be taken to coincide with the lower extreme fibre of the ‘beam’. For the por on of the building in the sagging mode, however, it is reasonable to assume that the neutral axis remains in the middle of the ‘beam’. Burland and Wroth showed that these selec ons of the posi ons of the neutral axis are consistent with observa ons of building performance. Expressions were derived rela ng the ra on ∆/L for the beam to the maximum rela ve bending strain (ϵb ) and diagonal strain (ϵd).The strains in a building with a maximum rela ve se lement ∆ can also be determined from these expressions which were presented in a generalised form by Burland et al (1977) as:
(13)
and
(14)
where
H
is the height of the building,
L
is the length of the building (but limited by any point of inflexion or extent of se lement trough as discussed above),
E and G
are respec vely the Youngs modulus and shear modulus of the building (assumed to be ac ng as a beam),
I
is the second moment of area of the equivalent beam (ie H 3/12 in the sagging zone and H 3/3 in the hogging zone), and
t
is the furthest distance from the neutral axis to the edge of the beam (ie H /2 in the sagging zone and H in the hogging zone).
The maximum bending strain ϵb and diagonal strain ϵd are likely to develop at the centre and quarter span points respec vely. Although masonry is not an isotropic material, the ra o E/G is o en taken as 2.6, which is consistent with an isotopic Poisson’s ra o of 0.3, and this value is recommended. Figure 5 shows a general case of a building affected by a tunnel se lement trough. It is assumed that the building follows the ground se lement trough at the founda on level. The point of inflexion of the se lement trough (defined by i for the case of a single tunnel) divides the building into two zones. In the hogging zone ( y > i ), where the neutral axis is at the bo om, all strains due to bending will be tensile. In the sagging zone, where the neutral axis is at the centre of the building, bending will cause both compressive and tensile strains. Within each zone, the maximum ra o ∆/L can be determined, i.e. ∆h /Lh in the hogging zone and ∆s /Ls in the sagging zone, as shown on Figure 6. For a given ra o ∆/L, the hogging mode is likely to be more damaging than the sagging mode. This procedure essen ally allows the building to be treated separately either side of the point of inflexion which is considered
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Appendix A
a reasonable approach. The maximum values of ∆h or ∆s are unlikely to occur at the centre of their respec ve span and in general it will be simplest to search for these numerically. It should be noted that this approach differs slightly from that suggested by Boscardin and Cording (1989) in which ∆/L was related to an angular distor on.
Hogging zone
Sagging zone
i Building
h
H Lh s Ls
Figure 6 Determina on of maximum rela ve se lement ra o ∆/L
In cases where the building span being considered has dimensions such that L >H , an addi onal ra o ∆sub / Lsub should also be determined by considering smaller sub-spans of length Lsub = H within the overall span and the associated ∆sub calculated using the procedure outlined above. For a par cular building span, the maximum ra o of ∆ /L determined using either the full building span length or Lsub should then be used in Equa ons 13 and 14. 3.3
Superposi on of horizontal ground strain The horizontal ground strains due to bored tunnel construc on will also contribute to building damage. The horizontal strains can be added directly to the bending strains giving:
ϵbt = ϵh + ϵb
(15)
where ϵbt is the total bending strain. In assessing building damage, the maximum tensile strain is required and this will generally be in the hogging zone where both ϵb and ϵh are tensile.
Appendix A
Crossrail: A technical guide for developers |
Page 25
2
d
-0.3 h
h
0.35
h
- d
Figure 7 Mohr’s circle of strain used to determine
Maximum tensile strain, dt
ϵdt
Diagonal (shear) strains and horizontal strains can be summed by making use of a Mohr’s circle of strain as shown on Figure 7. If a tensile horizontal strain, ϵh, is induced in the building, then in the ver cal direc on a compressive strain of -0.3ϵh will result (assuming a Poisson‘s ra o of 0.3). Two points on the Mohr’s circle are then (ϵh, ϵd) and (-0.3ϵh –ϵd) and the circle can be constructed as shown. The maximum tensile strain due to diagonal distor on, ϵdt is then given by:
(16) A ques on arises when determining the appropriate value of ϵh. The recommended approach is to use Equa ons 5 and 6 to calculate the horizontal movement at either end of a building span under considera on and the difference between these divided by the span length then gives an average horizontal strain. If a sub-span gives the maximum ∆ /L ra o, the average horizontal strain should be calculated for the par cular sub-span used. Calcula on of local horizontal strain using Equa on 8 is considered unduly conserva ve and is not recommended.
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| Crossrail: A technical guide for developers
Appendix A
4
Assessment of Damage
4.1
Damage to buildings by se lement will be classified into various categories of risk as given in Burland et al (1977) and in the Building Research Establishment Digest 251: negligible, very slight, slight, moderate, severe and very severe. These categories, together with typical repairs that might be required for masonry buildings, are described in Table 1 (page 27). Boscardin and Cording (1989) showed that these categories of damage are related to the magnitude of the maximum tensile strain induced in the structure, as shown in Table 1. A summary of the calcula on procedure and method of building assessment described in this document is given in Appendix B. An example calcula on is also included in Appendix B.
References Boscardin, M.D. and Cording, E.J. (1989). Building response to excava on induced se lement. Journal of Geotechnical Engineering, ASCE, Vol. 115, No 1, pp 1–21. Building Research Establishment Digest 251. Assessment of damage in low-rise buildings with par cular reference to progressive founda on movement. Burland, J.B., Broms B.B. and de Mello, V.F.B. (1977). Behaviour of founda ons and structures. State-of-the-art report, Session 2, Proc.9th Int. Conf. on Soil Mechanics and Founda on Engineering, Tokyo. Vol. 3, pp 495–546. Burland, J.B. and Wroth, C.P. (1974). Se lement of buildings and associated damage. Proc. Conference on Se lement of Structures, Cambridge. Pentech Press, pp 611–654. New, B.M. and O Reilly, M.P. (1991). Tunnelling induced ground movements: predic ng their magnitude and effect. 4th Int. Conf. on Ground Movements and Structures. Cardiff. O Reilly, M.P. and New, B.M. (1982). Se lements above tunnels in the United Kingdom — their magnitude and predic on. Tunnelling ‘82. Ed Jones, M.J. pp173–181. London, IMM. New B.M and Bowers K.H. Ground movement model valida on at the HEATHROW EXPRESS TRIAL TUNNEL – Tunnelling ’94. pp 301-329.IMM.London
Appendix A
Crossrail: A technical guide for developers |
Page 27
Table 1 Classifica on of visible damage to walls with par cular reference to ease of repair of plaster and brickwork or masonry (a er Burland, Broms and de Mello, 1977; Boscardin and Cording, 1989). Degree of damage*
DescripƟon of typical damage (ease of repair is in bold text)
Approximate crack width (mm) **
LimiƟng tensile strain (%)
0 Negligible
Hairline cracks of less than about 0.1mm are classed as negligible.
<0.1
0.0–0.05
1 Very slight
Fine cracks which can easily be treated during normal decoraƟon. Perhaps isolated slight fracture in building. Cracks in external brickwork visible on inspec on.
1
0.05–0.075
2 Slight
Cracks easily filled. RedecoraƟon probably required. Several slight fractures showing inside of building. Cracks are visible externally and some repoinƟng may be required externally to ensure weather ghtness. Doors and windows may s ck slightly.
5
0.075–0.15
3 Moderate
The cracks require some opening up and can be patched by a mason. Recurrent cracks can be masked by suitable linings. RepoinƟng of external brickwork and possibly a small amount of brickwork to be replaced. Doors and windows s cking. Service pipes may fracture. Weather ghtness o en impaired.
5 to 15 or a number of cracks > 3
0.15–0.3
4 Severe
Extensive repair work involving breaking-out and replacing secƟons of walls, especially over doors and windows. Windows and door frames distorted, floor sloping no ceably. Walls leaning or bulging no ceably, some loss of bearing in beams. Service pipes disrupted.
15 to 25 but also depends on number of cracks
> 0.3
5 Very severe
This requires a major repair job involving parƟal or complete rebuilding. Beams lose bearings, walls lean badly and require shoring. Windows broken with distor on. Danger of instability.
usually > 25 but depends on number of cracks
* In assessing the degree of damage, account must be taken of its loca on in the building or structure. **Crack width is only one aspect of damage and should not be used on its own as a direct measure of it.
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| Crossrail: A technical guide for developers
Appendix A
5
Summary of CalculaƟon Procedure and Building Assessment
5.1
For each tunnel likely to affect a building, determine the depth Z from the cross sec on. Choose relevant values for Vl and K and determine Vs (Equa on 3) and i (Equa on 4) for each tunnel. Also calculate Smax (Equa on 2) for each tunnel.
5.2
Determine points of inflexion of the se lement profile beneath the building. This may involve the calcula on of curvature where there are mul ple tunnels (Equa on 12). Hence define relevant building span lengths which will be limited by the extent of the building, the prac cal limit of the se lement trough and points of inflexion as appropriate.
5.3
Calculate values of Sv (Equa on 5) and Sh (Equa on 6) at the ends of the building span lengths. Use the change in Sh over the span length L to determine the average horizontal strain, ϵh.
5.4
For each building span, calculate the average horizontal strain and the maximum ra o. NB an addi onal search for maximum ∆ /L ra o is to be undertaken for sub-spans when L exceeds H, and if this value of ∆ /L is used, the average horizontal strain should be recalculated for the relevant sub-span.
5.5
Calculate values for ϵb (Equa on 13) and ϵd (Equa on 14) and combine these with to determine the maximum combined strains ϵbt (Equa on 15) and ϵdt (Equa on 16). Classify the building damage based on the maximum tensile strain according to Table 1.
Appendix B Example Calcula on of Tunnel Se lement and Associated Building Strains
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Appendix B
1
Example CalculaƟon of Tunnel SeƩlement and Associated Building Strains
Building
6.1m
7.5m
Made Ground
14.9m
0.5m
River Terrace Deposits
5m
London Clay
35m Westbound Tunnel
Eastbound Tunnel
Se lement predic on and building assessment
Geometry
Excavated diameter of tunnel = 6.6 m Depth tunnel axis below founda on = 14.9 – 0.5 ie 14.4m
Select
Volume loss parameter Vl and K as: , Vl = 0.02 (ie 2 per cent) K = 0.5 (tunnel and building founda ons dominated by pressure of London Clay.)
Se lement trough
Width parameter
i = Kz = 0.5x14.4 i = 7.2m
(Equa on 4)
Prac cal limit of se lement trough = 2.5i = 18m Check influence of westbound tunnel: Distance from tunnel axis to near edge of building = 35 – 5 – 7.5 = 22.5m This exceeds the limit of the se lement trough: only the eastbound tunnel needs to be considered.
Appendix B
1.1
Crossrail: A technical guide for developers |
Page 31
Define building span lengths to be considered.
Since only the eastbound tunnel is to be considered, only the point of inflexion at i=7.2m is relevant.
i=7.2m
Building
5 A B Lh
C Ls
7.5m In sagging zone,
In hogging zone,
Tunnel se lement Volume loss,
Max se lement above tunnel centre line (Equa on 2)
In assessing building damage, we require building movement at points A, B and C as shown in diagram above. Ver cal movement (Equa on 1):
(nb, y = distance to tunnel centre line)
Horizontal movement (Equa on 6):
Average horizontal strain:
(tension posi ve)
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| Crossrail: A technical guide for developers
Appendix B
PosiƟon on building
A
B
C
Distance from tunnel centre line
12.5
7.2
5
Ver cal movement
0.0084
0.0230
0.02979
Horizontal movement
0.00729
0.01150
0.010344
Ground slope
-0.00203 (1:494)
-0.00319 (1:313)
-0.00287 (1:348)
Hogging zone
Sagging zone
Length
5.3
2.2
Change in horizontal movement
-0.00421
0.001156
Horizontal strain
0.000794
-0.000525
(tension posi ve)
Determine
Hogging
A
Sagging
h
A B B
s
CC
Since only one tunnel affects building, max ∆ in sagging or hogging zone can be determined mathema cally
Appendix B
Crossrail: A technical guide for developers |
Se lement trough shape
y
1
dS dy
a12 2
Slope
For general chord between points 1 and 2 in se lement trough, average slope
By itera on, determine y´ where Then
Page 33
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| Crossrail: A technical guide for developers
Appendix B
Hence: Hogging zone
Sagging zone
L
5.3
2.2
Change in ver cal se lement
0.0084-0.023 = -0.0146
0.023-0.02979 = -0.00679
Average slope
-0.00275
-0.00309
10.125
5.913
0.01410
0.02706
2) S along straight chord
0.01494
0.02697
∆ = (2) – 1)
0.000839
-0.000086
0.000158
-0.00004
y´ (where
average slope)
1)
(hogging posi ve)
;
;
Appendix B
Crossrail: A technical guide for developers |
Sagging zone
;
;
,
,
; (i.e. compressive)
Horizontal strain
(compressive)
(tensile)
Hogging zone
,
;
,
, ;
Horizontal strain = 0.000794 (tensile) (tensile) (tensile) Maximum tensile strain = 0.000888 (bending in hogging zone). Category 2 – slight (using Table 1)
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| Crossrail: A technical guide for developers
1.2
Example Road
Appendix B
N
Page 36
X
Loca on Plan (Scale 1:250)
Crossrail Building Response Assessment Example Road View and Loca on
Geotechnical Consul ng Group September 1992 Ref 0/1
Appendix B
Crossrail: A technical guide for developers |
Page 37
General descrip on The building is a two storey Victorian masonry structure. The building has no basement and the founda ons are at a depth of 0.5 m below ground level. The centreline of the proposed eastbound running tunnel will be located approximately 5m north-east of the building at a depth of 14.4m below the assumed founda on level. The centreline of the proposed westbound running tunnel will be located 35m to the south-west of the eastbound tunnel. The westbound tunnel will have a negligible effect on the building. Building response Maximum se lement 30mm Maximum ground slope 1:313 Maximum tensile strain 0.09% Classifica on of damage LimiƟng tensile strains
DescripƟon
Category of damage
0.0 – 0.05%
negligible
0
0.0 – 0.075%
very slight
1
0.075 – 0.15%
slight
2
0.15 – 0.30%
moderate
3
severe to very severe
4/5
greater than 0.30%
The building is in the ‘slight damage’ category.
Crossrail Building Response Assessment Example Road Summary of a building and Assessment
Geotechnical Consulting Group September 1992 Ref 0/2
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| Crossrail: A technical guide for developers
Appendix B
7.5m (approx)
Building
6.1m (approx) Make Ground
14.9m
Westbound running tunnel
Eastbound running tunnel
6.6m O
6.6m O
River Terrace Deposits
5m
London Clay
35m (approx)
N
A
A
Crossrail Building Response Assessment
Geotechnical Consul ng Group September 1992
Example Road Plan and Sec on (scale 1:500)
Ref 0/3
Appendix B
Crossrail: A technical guide for developers |
Page 39
Building Ground level 2
20
4
40
6
60
Se lement (mm)
Ver cal scale (m)
0
8 10 12
Tunnel
14 16 18 16
14
12
10
8
6
4
2
0
2
4
6
8
10
Horizontal scale (m)
Se lements shown at exaggerated scale rela ve to the building. Tunnel
Building
depth below GL
14.9m
width
7.5m
diameter
6.6m
height
6.1m (to eaves)
volume loss
2%
founda on depth
0.5m
K
0.5
offset
5m
E/G
2.6
Smax
37.9m
max. se lement
29.8mm
i
7.2m
max. slope
1:313
max. tensile strain
+0.09% (bending)
Point of inflexion shown • on curve
Crossrail Building Response Assessment Example Road Tunnel and Building Details
Geotechnical Consul ng Group September 1992 Ref 0/4
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| Crossrail: A technical guide for developers
Appendix B
Hogging
Sagging
Building
0 Horizontal
20 Ver cal
30 40 50 16
15
14
13
12
11
10
9
8
7
6
5
4
Horizontal scale (m) Displacements shown at exaggerated scale rela ve to building
Strains in Building strain components
maximum combined tensile strengths
Hogging zone
Sagging Zone
horizontal
+0.079%
-0.053%
bending
+0.009%
+0.002%
shear
+0.015%
+0.004%
bending
+0.089%
-0.051%
diagonal
+0.082%
+0.015%
Compressive strains —ve; tensile strains given +ve Maximum tensile strain for building: +0.089% (Category 2, Slight)
Crossrail Building Response Assessment Example Road Details of Building Response
Geotechnical Consul ng Group September 1992 Ref 0/5
Displacement (mm)
10
Appendix B
2
Crossrail: A technical guide for developers |
Page 41
Addendum to Appendix B
5 October 1992 Addendum to the document en tled ‘Predic on of ground movements and associated building damage due to bored tunnelling’ by Geotechnical Consul ng Group. Dated September 1992.
2.1
Framed buildings on shallow founda ons Reinforced concrete framed structures are more flexible in shear than masonry structures, and are consequently less suscep ble to damage. Nevertheless, for the purposes of a phase 2 assessment of poten al damage, framed buildings on shallow founda ons should be treated as masonry structures as outlined in the document. In the event that a damage risk category of ‘moderate’ or higher is indicated, considera on of the likely behaviour of the framed structure in terms of rela ve rota on (Burland et al, 1977) may show that a detailed phase 3 assessment is not necessary.
2.2
Buildings on piled founda ons The document states that the procedure for calcula ng building strains is only relevant to buildings on shallow founda ons. Field measurements of performance of buildings on piled founda ons are very sparse. For the purposes of a phase 2 assessment of poten al damage of a pile building, two approaches should be undertaken. Approach 1 is to ignore the piles and treat the building as if it is on shallow founda ons at pile cap or ra level. The ground movements at that level should be calculated, using the procedure described in the document. The associated building strains should then be calculated, assuming iden cal ver cal and horizontal movements of the building founda ons and ground. Approach 2 is to calculate the ground se lements at the founding level of the piles, together with the associated building strains assuming the building follows the same se lement profile. For calcula on of horizontal strains, the building should be assumed to experience the same horizontal movements as if it were on shallow founda ons at pile cap or ra level (i.e. as for Approach 1). For the purpose of a phase 2 assessment, the predicted damage risk category should be quoted for both approaches, and the more onerous risk category assumed. In the event that a damage risk category of ‘moderate’ or higher is indicated, in the case of framed buildings considera on of the likely behaviour of the structure in terms of rela ve rota on (Burland et al, 1977) may show that a detailed phase 3 assessment is not necessary.
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| Crossrail: A technical guide for developers
2.3
Single and Mul ple Tunnels
Appendix B
The document outlines the approach to be adopted for single and mul ple tunnels. In some cases a building might be more adversely affected by a single tunnel than by the final combina on of mul ple tunnels. Consultants should take into account the stages of tunnels construc on when undertaking the phase 2 assessment in order to ascertain the most cri cal stage. 2.4
Longitudinal Se lement Effects The document outlines a simple procedure for undertaking phase 2 assessments in terms of a plane sec on, ie only the effects of the se lement trough transverse to the tunnel are considered. Longitudinal se lement effects, arising from the progressive trough generated ahead of the tunnel face, are not considered in the document. This is a reasonable approach for the majority of buildings located either side of the tunnel centreline. However, there may be cases where a building close to or directly above the tunnel centreline might experience more damage from the progressive longitudinal trough than from final transverse se lement profile. If it is felt that certain buildings might be in this category, consultants should consider the possible effects of the longitudinal se lement trough, assuming the shape of the trough to be summarised by Rankin (1988). The associated building strains should then be calculated, assuming iden cal ver cal and horizontal movements of the building founda ons and ground. References Burland, JB, Broms, B.B. and de Mellow, V.F.B. (1977). Behaviour of founda ons and structures. Stateof-the-art report, Session 2, proc. 9th Int. Conf. on Soil Mechanics and Founda on Engineering, Tokyo. Vol. 3, pp. 495–546. Rankin, W.J. (1988). Ground movements resul ng from urban tunnelling: predic ons and effects. Engineering Geology of Underground Movements, Geological Society Engineering Geology Special Publica on No. 5, pp 79–92.
Appendix C Noise and Vibra on Assessment Summary
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| Crossrail: A technical guide for developers
Appendix C
Crossrail Contract XR/K/680 Noise and Vibra on Assessment and Mi ga on Report No 075/14 Resilient Slab Track Tunnel Vibra on Predic ons Revision 3 March 1998
Crossrail Contract XR/K/680 Noise and Vibra on Assessment and Mi ga on Report No 075/14 Tunnel Vibra on Predic ons Issue and Revised Record Issue
Date
Originator
Checked
Approved
Descrip on
Status
1 1 1 1
11/06/96 10/07/96 31/07/96 16/03/98
RMTT RMTT RMTT RMTT
FLT JSP JSP FLT
RMTT RMTT RMTT RMTT
Report Report Report Report
1st Issue Revision 1 Revision 2 Revision 3
Rupert Taylor Ltd Consultants in Acous cs, Noise and Vibra on Spring Garden, Fairwarp, Nr Uckfield, East Sussex, TN22 3BG Telephone: 01825 712435 Fax: 01825 712542
Appendix C
Crossrail: A technical guide for developers |
Page 45
1
IntroducƟon
1.1
This report provides predic ons of the vibra on of the wall of the tunnels in the Crossrail central sec on, for use in the assessment of groundborne noise in adjacent buildings.
2
DescripƟon of the Model
2.1
The predic on model used for these predic ons employs an algorithm for the solu on of the wave equa on for the propaga on of waves in bars, plates and solids, using finite difference methods. The model computes vibra on of each element as a func on of me, which is then subjected to Discrete Fourier Transform using a standard Fast Fourier Transform algorithm. The bandwidth of the predic on results covers the 1/3 octave bands centred on 20Hz to 160Hz.
2.2
The model consists of a sec on of tunnel the length of one rail vehicle, connected end-to-end to create an infinitely long tunnel and train. In view of the fact that the length of a 12-car Crossrail train is 47 mes the tunnel diameter, the modelling of an infinitely long train is valid. The tunnel is modelled as a rolled-up curved plate surrounded by soil. Each rail is modelled as a beam supported on periodic resilient supports. The train is represented by the unsprung masses of the wheels and associated equipment, the sprung bogie masses, the secondary suspension and the car body.
3
AssumpƟons
3.1
The following assump ons were made: Track
Vehicles
rail mass
56.4kg/m
per rail 2
rail s ffness
4.665MNm
per rail
rail damping
0Ns/m
per rail
rail pad s ffness (dynamic)
25.6MN/m
per metre of rail
rail pad damping ( η )
0.1
dimensionless
Hertzian contact s ffness
1.2GN/m
per wheel
unsprung mass
835kg
per wheel
sprung mass
815kg
per wheel
primary suspension s ffness
1.3MN/m
per wheel
primary suspension damping
10kNs/m
per wheel
secondary suspension s ffness
117.5kN/m
per wheel
secondary suspension damping
11.651kNs/m
per wheel
body mass
5705kg
per wheel
Note: where the Crossrail design aim for groundborne noise of 40dB LAmax,S due to the passage of one Crossrail train cannot be met using baseplates having the dynamic s ffness and damping quoted above, a baseplate with a lower s ffness of 14MN/m per metre of rail may be considered.
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| Crossrail: A technical guide for developers
Appendix C
3.2
The baseplate specifica on used in the above assump ons has a higher dynamic s ffness than CRL is currently proposing to adopt, in order to ensure that a conserva ve predic on of noise level is considered in the developer’s design.
3.3
Tunnel Design The tunnel assump on was a 6m inside diameter tunnel with 300mm thick concrete linings.
3.4
Rail Roughness A roughness spectrum of 30dB re 1 micron in the 1/3 octave band centred on a wavelength of 2m, sloping at a rate of -15dB per decade to 0dB in the 1/3 octave band centred on 0.02m. This spectrum was used to represent the combined effects of wheel and rail roughness.
3.5
Soil The soil characteris cs used were those of London Clay.
4
PredicƟon Results
4.1
The results are presented in tabular form in Tables 1 and 2 for two train speeds of 80km/h and 100km/h respec vely, in terms of 1/3 octave spectra of radial tunnel wall velocity in decibels r.e. 1 nanometre per second, for 26 posi ons around the tunnel circumference. The same data are also plo ed in Figures 1 to 4.
5
ApplicaƟon of the Results
5.1
The results may be used for es ma ng the likely level of groundborne noise inside buildings above the tunnel alignment. For this purpose it is necessary to take account of the effect of vibra on propaga on through the soil, of coupling loss factor between the soil and the building, and the dynamic response of the building. A er applying correc ons for these effects, the results in terms of the root-mean-square (rms) velocity in 1/3 octave bands can be used to es mate the sound pressure level inside a typical room. In many cases, the rela onship between room sound pressure level and ‘rms’ velocity of the room surfaces is approximately equivalent to Lp= Lv –27dB, where Lp is the 1/3 octave band sound pressure level: Lv is the ‘rms’ vibra on velocity in dB re 1 nanometer per second.
Appendix C
5.2
Crossrail: A technical guide for developers |
Page 47
Propaga on through the soil is a very complex phenomenon, since the vibra on is propagated in three ways — as shear, compression and surface waves, and as shown by the results given in this report, the source strength varies around the tunnel circumference. A worst-case approach would be to take the highest levels in the tunnel wall ‘visible’ to the receiving structure, and use a distance func on as follows:
Where Lt is the tunnel wall radial velocity for a tunnel of radius r0 and Lr is the soil radial velocity at distance r, both in dB re 1 nanometer/second, cs is the phase speed of compression waves in soil with loss factor η and is the angular frequency of each 1/3 octave band in radians per second. The coupling loss factor and building response generally have opposite sign and as a first order approxima on they may be assumed to cancel. In the case of piled founda ons, if r is taken to be the shortest distance to any part of the nearest pile, a worst-case es mate will be obtained. Any distance units may be used, provided they are consistent throughout. 5.3
The overall 1/3 octave spectrum may be converted to dB(A) by decibel addi on of the band levels a er applying the value of the ‘A-weigh ng’ curve of each band centre frequency.
5.4
To obtain a more precise predic on of groundborne noise levels in buildings, it is necessary to use numerical modelling methods based on finite-difference or finite-element techniques.
91
100
103
95
92
88
90
94
88
25
31.5
40
50
63
80
100
125
160
83
89
86
85
90
92
102
99
90
89
14
84
89
82
79
83
85
96
95
85
86
28
87
93
89
88
91
92
99
96
84
85
42
86
91
90
89
93
96
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101
90
89
55
88
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86
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96
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103
92
92
69
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94
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91
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166
81
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Degrees
82
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31.5
40
50
63
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100
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160
0
20
Hz
84
89
84
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85
80
83
86
98
96
89
88
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93
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91
92
101
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42
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55
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69
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82
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85
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94
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91
100
96
96
100
104
114
113
104
99
222
91
98
95
94
99
104
113
111
103
100
222
91
100
96
95
99
104
114
112
103
99
235
91
98
95
93
99
103
112
110
101
99
235
90
99
94
94
98
102
111
109
101
97
249
90
97
93
91
97
101
110
108
99
98
249
88
95
94
93
96
99
109
107
99
96
263
89
94
92
91
95
98
107
106
96
96
263
87
95
93
90
93
96
107
105
97
94
277
88
94
90
88
93
95
106
104
93
94
277
87
93
90
88
93
96
107
103
96
92
291
88
93
88
86
93
96
105
103
92
92
291
85
90
92
90
94
96
105
101
93
89
305
86
91
90
89
93
96
104
101
90
89
305
87
94
93
89
91
92
101
97
88
86
318
87
93
89
88
91
92
99
96
84
85
318
84
90
85
80
83
86
98
96
89
88
332
84
89
82
79
83
85
96
95
85
86
332
84
89
89
86
90
92
103
100
93
91
346
83
89
86
85
90
92
102
99
90
89
346
89
95
93
90
93
94
104
101
94
92
360
88
94
90
88
92
95
103
100
91
90
360
| Crossrail: A technical guide for developers
89
86
90
92
103
100
93
91
14
Degrees
Table 2 – 1/3 Octave band spectra of vibra onvelocity of tunnel circumference (0 degrees = crown), dB re 1 nanometre per second. Train speed: 100km/h
90
0
20
Hz
Table 1 – 1/3 Octave band spectra of vibra onvelocity of tunnel circumference (0 degrees = crown), dB re 1 nanometre per second. Train speed: 80km/h
Page 48 Appendix C
Appendix C
Crossrail: A technical guide for developers |
Figure 1 Distribu on of vibra on levels around tunnel circumference (0 degrees – crown) RST 80 km/h
Page 49
Page 50
| Crossrail: A technical guide for developers
Figure 2 Distribu on of vibra on levels around tunnel circumference (0 degrees – crown) RST 100 km/h
Appendix C
Appendix C
Crossrail: A technical guide for developers |
dB re 1 nm/s
Figure 3 Distribu on of vibra on levels around tunnel circumference – RST 80/km/h
Page 51
Page 52
| Crossrail: A technical guide for developers
Appendix C
dB re 1 nm/s
Figure 4 Distribu on of vibra on levels around tunnel circumference – RST 100/km/h
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