香港基坑支护设计文件需要满足屋宇署发布的“挖掘與側向承托圖則的規定《建築物（管理）規例》第 8(1)(bc) 條”相关规定。具体内容如下：

关于香港基坑开挖与基坑支护设计文件的规定《建筑物（管理）规例》第 8(1)(bc) 条

Requirements for an Excavation and Lateral Support Plan Building (Administration) Regulation 8(1)(bc)

引言 Introduction

大型挖掘工程，即使是浅层挖掘，如果设计不当亦是非常危险的。如建筑工程涉及挖掘工序，认可人士、注册结构工程师及注册岩土工程师必须采取足够的预防措施，以确保公众安全。如工程包括打桩及类似操作，有关监察规定的详情应参阅《认可人士、注册结构工程师及注册岩土工程师作业备考》APP-18及APP-137。

Bulk excavation, even if shallow, can be dangerous if not properly designed. Authorized persons, registered structural engineers (RSE) and registered geotechnical engineers (RGE) are reminded to take adequate precautions to ensure public safety whenever excavation is found necessary as part of the work. Reference shall be made to PNAP APP-18 and PNAP APP-137 on details of monitoring requirements if piling and similar operations are included.

呈交开挖与侧向支撑设计文件的准则

Criteria for Submission of Excavation and Lateral Support Plans

2. 一般而言，较深的挖掘工程如果出现坍塌会导致严重后果，因此该等工程的挖掘与侧向承托图则根据《建筑物（管理）规例》第8(1)(bc)条，须呈交屋宇署审批。

In general terms, excavation and lateral support (ELS) plans are required under Building (Administration) Regulation 8(1)(bc) to be submitted for approval where excavations of substantial depth are to be carried out, the collapse of which would cause serious consequences.

3. 以下所述挖掘工程必须呈交 挖掘与侧向承托图则以供审批：

(a) 挖掘的深度超过2.5米，以及其长度超过5米；及(b) 有可能影响道路、建筑物、构筑物、坡度超过30度的斜坡或直径不少于75毫米的主输水管，受影响范围的定义为，由挖掘处底部沿45度向上以至地面之间的范围。

3. ELS plans will be required to be submitted to the Buildings Department (BD) for approval where the excavation works to be carried out are:

(a) deeper than 2.5 m and greater than 5 m in length; and

(b) liable to affect any road, building, structure, slope steeper than 30° or water main 75 mm in diameter or greater, the affected area being defined as within the 45° line up from the base of the excavation to the ground surface.

4. 如上述条件适用，但挖掘与侧向承托图则未按《建筑物（管理）规例》第8(1)(bc)条的规定呈交及获得批准，屋宇署不会发出有关工程的展开工程同意书。

4. Where the above conditions apply, consent to commence ELS works would not be given if ELS plans, as prescribed in Building (Administration) Regulation 8(1)(bc), have not been submitted and approved.

5. 对于须按上文所述呈交审批的挖掘与侧向承托图则，注册结构工程师须拟备及签署图则、结构设计以及评估挖掘工作和地下水位变化对毗邻构筑物影响的结构评估报告。至于挖掘深度超过4.5米的挖掘与侧向承托图则，注册岩土工程师须编写及签署辅证文件，例如岩土评估、岩土详细资料及计算资料、岩土报告、地盘勘测报告或土地勘测报告等。这些辅证文件应连同挖掘与侧向承托图则一并呈交。

5. Where ELS plans are required to be submitted for approval as stipulated above, an RSE would be required to prepare and sign the plans and structural design as well as the structural assessment report of the effects of the excavation and dewatering on adjoining structures. For ELS plans with excavation depth deeper than 4.5m, an RGE would be required to prepare and sign the supporting documentations, such as geotechnical assessment, geotechnical details and calculations, geotechnical reports, site investigation reports or ground investigation reports, which should accompany the ELS plans submission.

6. 挖掘与侧向承托图则可以分两个阶段呈交，但第一阶段的呈交文件必须能够论证整体计划的可行性。第一阶段呈交的图则应该包括挡土结构，例如排桩或地下连续墙，以及支撑平面图和施工程序。辅证岩土工程文件也应该同时提交。第一阶段呈交的计算资料，应该包括整个工程中对地面移动的接近实际的预测。第二阶段呈交的图则，通常包括侧向承托系统的结构详图，当中包括按照已批准的第一阶段图则中就每个挖掘程序所制定的承托详图。

6. It is permissible to have the ELS plans submitted in two stages, provided that the first stage submission demonstrates the feasibility of the entire scheme. Plans submitted at the first stage should show the lateral support system, for example sheet piles or a diaphragm wall, together with a strutting layout and the construction sequence. The supporting geotechnical documentation should also be provided. Calculations submitted at the first stage should include realistic ground movement estimates for the entire works. The second stage submission normally would include the structural details of the lateral support system, including detailing of the struts for each stage of excavation according to the approved first stage submission.

综合安全系数方法Global Safety Factor Method

7.挖掘与侧向承托工程的设计通常是采用综合安全系数方法进行。该方法使用未考虑分项系数的土体强度参数和未考虑分项系数的荷载进行稳定性检查，以符合《建筑物（建造）规例》第15条的规定。

7. The global safety factor method has generally been used in the design of ELS works. In this method, unfactored soil strength parameters and loads are used in the stability checks for compliance with Building (Construction) Regulation 15.

极限状态分项系数方法Limit State Partial Factor Method

8. 英国建造业研究及信息协会 (Construction Industry Research and Information Association) (CIRIA) 在2003年出版的C580号报告(CIRIAC580报告)，提出极限状态分项系数方法，作为设计埋置挡土墙的方法。在这方法上，土壤与结构物的相互作用要在“正常使用极限状态”及“最终极限状态”的情况下进行分析。挖掘与侧向承托工程设计内的土壤参数及荷载必须乘以分项系数。由屋宇署、土力工程处及业界于2011年进行的检讨结果显示，极限状态分项系数方法可以作为综合安全系数方法以外的另一项可供选择的方法。然而，采用极限状态分项系数方法，必须符合“挖掘与侧向承托工程设计须知＂的相关指引及规定（见附录A）。

8. With the publication of Report No. C580 by the Construction Industry Research and Information Association of the United Kingdom (CIRIA Report No. C580) in 2003, a Limit State Partial Factor (LSPF) method for embedded retaining walls was introduced. In this method, soil structure interaction analysis is carried out for both the serviceability limit state (SLS) and ultimate limit state (ULS) conditions. Soil parameters and loads shall be applied with partial factors in the design of ELS works. A review conducted by the BD, the Geotechnical Engineering Office of the Civil Engineering and Development Department and the industry in 2011 concluded that the LSPF method could be used as an alternative to the global safety factor method. This alternative method shall conform to the guidance and requirements given in the "Notes on Design of Excavation and Lateral Support Works" at Appendix A.

呈交文件的规定Submission Requirements

9.提交挖掘与侧向承托工程的设计建议时，应在图则及计算文件上列明所使用的设计方法。使用极限状态分项系数方法的挖掘与侧向承托工程设计的呈交程序，跟使用综合安全系数方法的相同。然而，挖掘与侧向承托工程的设计不得混用上述两种设计方法。

9. In all ELS plans submissions, the design method used should be stated on the plans and calculations. The submission procedures for the LSPF method for ELS works will be the same as that for the global safety factor method. However, ELS works design based on a mixture of both methods are not allowed.

10. 所有辅助设计建议的计算机程序，均应呈交屋宇署作预先认可。有关预先认可计算机程序的一般规定，请参阅《认可人士、注册结构工程师 及注册岩土工程师作业备考》ADM-6。即使某一个计算机程序可应用于两种设计方法上，该计算机程序仍需就个别设计方法呈交屋宇署作预先认可。

10. Computer programs to be used to support the design proposals should be submitted to the BD for prior acceptance. The general requirements for prior acceptance of computer programs are given in PNAP ADM-6. Even if a computer program is applicable to both design methods, separate application for prior acceptance of the computer program for each design method is required.

附录A Appendix A

1. 简介 1. Introduction

1.1 本文为在香港进行挖掘与侧向承托工程的设计提供技术指引及规定。本须知第2部分是关于挖掘与侧向承托工程的一般指引及规定，现已应用于综合安全系数方法，并适用于极限状态分项系数方法。第3部分的指引及规定只适用于极限状态分项系数方法，包括为配合本地的设计标准及运作而对CIRIAC580报告所作的各项修订。

1.1 This document provides technical guidance and requirements for the design of excavation and lateral support (ELS) works in Hong Kong. Those given in Section 2 are general guidance and requirements for ELS works, which are currently adopted in the global safety factor method and are also applicable to the Limit State Partial Factor (LSPF) method. Those given in Section 3 are applicable to the LSPF method only and these include the modifications to the CIRIA Report No. C580 to suit local design standards and practice.

2. 一般指引及规定（适用于综合安全系数方法及极限状态分项系数方法）

2. General Guidance and Requirements (APPLICABLE TO BOTH GLOBAL SAFETY FACTOR METHOD AND LSPF METHOD)

2.1 “正常使用极限状态”检查

2.1 Serviceability Limit State (SLS) Checks

2.1.1 如有需要，应进行“正常使用极限状态＂检查，以评估对毗邻建筑物、构筑物、设施及土地所造成的影响。

2.1.1 Where necessary, SLS checks should be carried out to assess the impacts on adjoining buildings, structures, services and land.

2.1.2 就评估因建造挡土墙、降低地下水位及进行挖掘所引致的地层移动及挡土墙侧向移动，可参照土力工程处刊物第1/90号所载的指引行事。

2.1.2 For the assessment of ground movement and lateral wall movement caused by retaining wall installation, dewatering and excavation, the guidance given in GCO Publication No. 1/90 could be used.

2.2 土壤刚度

2.2 Soil Stiffness

2.2.1在应用已公布的可靠个案资料中的土壤刚度和标准贯入测验的“N＂值之间的相互关系时，应考虑土壤的类别，以及为得出相互关系而在反演分析中使用的计算机程序。

2.2.1 In applying correlations between soil stiffness and SPT ‘N’ values from reliable published case histories, account should be taken of the soil type and the computer program used in the back analyses for deriving the correlation.

2.3 因水力所引致的坍塌

2.3 Hydraulic Failure

2.3.1 应参照土力工程处刊物第1/90号第6.2.4段所载的指引，并使用最小有1.5的安全系数以预防因水力所引致的坍塌。

2.3.1 The guidance given in Section 6.2.4 of GCO Publication No. 1/90 should be followed and a minimum factor of safety of 1.5 should be used to guard against hydraulic failure.

2.3.2 在进行设计时，应考虑土地的不确定状况（例如土壤渗透的分层性和非均质性），以及设计图在特定的地盘状况下应用时所遇到的不确定情况。

2.3.2 In the design, account should be taken of the uncertainties in ground conditions (e.g. soil layering and heterogeneity in permeability) and the uncertainties in the application of the design charts in the particular site conditions.

2.4 设计报告及设计检讨

2.4 Design Report and Design Review

2.4.1 设计报告应由注册结构工程师及注册岩土工程师核证。该报告须说明：

(a)有关分析显示有足够安全度以防止挖掘坍塌；及

(b)设计假定已通过验证和证实为有效，以及工程在建造过程中按照指定程序进行的前提下，挖掘与侧向承托工程不会引致不可接受的影响。

2.4.1 The design report should be certified by the RSE and RGE. It should state that:

(a) the analyses demonstrate that there is an adequate safety margin against collapse of the excavation, and

(b) there will be no unacceptable impacts due to the ELS works provided that the design assumptions are verified and found to be valid and the works are being carried out as specified during construction.

2.4.2设计报告应显示在建造过程中须复核和验证的设计假定、基于主要的参数而须进行监测和检查的计算结果，以及须在建造过程中视察和核证的重要工作程序。

2.4.2 The design report should indicate the design assumptions required to be reviewed and verified during construction, the range of computation results for the key parameters requiring monitoring and checking, and the critical working procedures requiring inspection and certification during construction.

2.4.3 应提供一份设计报告副本予负责的合资格地盘监督人员。

2.4.3 A copy of the design report should be made available to the qualified site supervision personnel responsible.

2.4.4 应进行监测，以便在建造工程进行期间检讨和检查有关设计的表现。最低限度应对地表沉降／隆起和水压进行监测，以便提供数据作设计检讨、风险管理／控制和表现检讨之用。如坍塌会对生命构成重大危险或会造成重大的财物损失，亦应一并监测直立构件的挠度。

2.4.4 Monitoring should be carried out to review and check the performance of the design during construction. As a minimum, ground settlement/heave and piezometric pressures should be monitored to provide data for design review, risk management/control and performance review. Where there is significant risk to life and property in the event of a failure, monitoring of the vertical member’s deflection should also be carried out.

3. 只适用于极限状态分项系数方法的指引及规定

3. Guidance and Requirements (APPLICABLE TO THE LSPF METHOD ONLY)

3.1 范围

3.1 Scope

3.1.1 极限状态分项系数方法可用于挖掘与侧向承托工程，其中包括挡土墙嵌入岩石的该等工程，但有关方法不适用于挡土墙埋置深度完全由软黏土支撑的挖掘与侧向承托工程。

3.1.1 The LSPF method can be used for ELS works including those with walls socketed in rock, but is not applicable to those with embedded depth of the wall entirely supported by soft clays.

3.2 设计参数

3.2 Design Parameters

3.2.1 应采用《岩土指南》第一册 (Geoguide 1) （第二版）所建议的最低分项系数及附加荷载，以及指南中所载有关地盘勘测、地层模拟、拣选岩土参数及设计水压的指引。

3.2.1 The minimum partial factors and surcharge loading recommended in Geoguide 1 (second edition), together with its guidance on site investigation, ground modelling, selection of geotechnical parameters and design water pressures, should be adopted.

3.3 结构设计

3.3 Structural Design

3.3.1 结构设计时应采用极限状态分项系数方法。从“正常使用极限状态”（依据CIRIAC580报告所载的方法计算）中得到的内力及弯矩考虑1.4而非1.35作为最低荷载分项系数参与计算。

3.3.1 The LSPF method should be used for structural design. A minimum factor of 1.4 instead of 1.35 should be applied to the forces and bending moments obtained from the SLS calculations carried out in accordance with the CIRIA Report No. C580.

3.3.2 设计可能须采用相关结构设计守则所载的分项系数来作额外的结构计算，以复核有关的结构构件。

3.3.2 Additional structural calculations using the partial factors given in the relevant structural design codes may be required to check the structural members.

3.4 “最终极限状态”检查

3.4 Ultimate Limit State (ULS) Checks

3.4.1 应使用极限平衡方法或土壤与构筑物相互作用分析来进行“最终极限状态”计算，以确保稳定性及具有足够安全度。

3.4.1 ULS calculations should be carried out using limit equilibrium method or soil structure interaction analysis to ensure stability with an adequate safety margin.

3.4.2 如“最终极限状态”检查是依照本附录所提供的建议进行，便无须跟从综合安全系数方法的要求而另外使用2.0的综合安全系数就弯矩不稳定性（即倾覆及剪出的破坏模式）进行检查。

3.4.2 When ULS checks are based on the recommendations given in this Appendix, there is no need to carry out separate checks against moment instability (i.e. overturning and kick-out failures) using a global factor of 2.0, as required in the global safety factor method.

3.5 “最终极限状态”检查的灵敏度分析

3.5 Sensitivity Analyses in ULS Checks

3.5.1 CIRIAC580报告提及，可使用极限平衡方法来决定所需的最少埋置深度，以确保有足够安全度以防止弯矩不稳定性。另一个选择是使用土壤与构筑物相互作用分析方法。

3.5.1 Under the CIRIA Report No. C580, the limit equilibrium method may be used to determine the minimum wall embedment depth required to ensure an adequate safety margin against moment instability. Alternatively, soil structure interaction analyses method may be carried out.

3.5.2 在土壤与构筑物相互作用分析中，埋置深度的轻微减少可引致最大墙挠度／支撑荷载迅速增大，反映有关设计对埋置方面微细改变的灵敏反应。因此，在选择一个合适的设计埋置深度数值时，应考虑灵敏度分析结果及在施工控制和监督制度下可达至的建筑容限。

3.5.2 In soil structure interaction analyses, there could be a rapid increase in the maximum wall deflection/strut loads upon a small reduction in the wall embedment depth, reflecting the sensitivity of the design to small variations in wall embedment. Hence a suitable value of design wall embedment depth should be selected to take into account the results of sensitivity analysis and the construction tolerance that can be achieved under the construction control and supervision regime imposed.

3.5.3 另外，就支撑承托水平可能出现偏差（±0.5米）及挡土墙后面的附加荷载亦可能出现偏差（十足附加荷载／无附加荷载）的问题，应就单支撑承托挖掘个案进行坍塌或过量变形的“最终极限状态＂的灵敏度分析。分析的结果应用作评估设计及／或监督有关工程时所须采取的行动。

3.5.3 In addition, sensitivity analyses against the ULS of collapse or excessive deformation should be carried out for cases of singly propped excavations, with respect to possible deviations in the prop level (± 0.5m) and surcharge behind the wall (full surcharge/without surcharge). The results of the analyses should be used to assess the actions needed in the design and/or supervision of the works.

3.6 嵌入岩石的挖掘与侧向承托工程的设计

3.6 Design of ELS Works Socketed in Rock

3.6.1 有关嵌入岩石段的设计原则和不稳定性检查，应参考《岩土指南》第一册（Geoguide1）（第二版）第11章就嵌入岩石的悬臂式挡土墙的设计所概述的极限状态分项系数方法。

3.6.1 For the design principles and instability checks of rock sockets, reference should be made to the LSPF method for the design of rock-socketed cantilever walls as outlined in Chapter 11 of Geoguide 1 (second edition).

3.7 渐进性破坏

3.7 Progressive Failure

3.7.1 注册结构工程师／注册岩土工程师应就失去一个支撑承托的情况评估有关风险，评估应包括考虑承建商建议的施工方法及程序。如有显著风险，注册结构工程师／注册岩土工程师应进行渐进性破坏检查或提供风险缓解措施以应对其设计中的意外情况。

3.7.1 The RSE/RGE should assess the risk of loss of a single strut support scenario, taking into account the contractor's proposed method and sequence of work. If the risk is evident, the RSE/RGE should either carry out a progressive failure check or provide risk mitigation measures to deal with the accident scenarios in his design.

3.7.2 进行渐进性破坏检查的目的，是要确保挖掘与侧向承托工程的设计在出现失去一个支撑承托的情况时，在结构和岩土方面仍有足够安全性。为防止渐进性破坏，可能需要改善结构构件的布局，以及提供较密的结构承托或加大横挡。

3.7.2 The purpose of carrying out a progressive failure check is to ensure the structural and geotechnical adequacy of the ELS works design in the event that the loss of a single strut support occurs. Improving the layout of structural members and provision of structural supports at close spacing or large walings may be required to prevent progressive failure.

3.7.3 可选择提供全面的风险缓解措施，以代替进行渐进性破坏检查。这些措施可包括加强施工机械的控制机制，例如在反铲挖土机的机械臂和后端装上探测距离感应器，以避免撞击结构承托，以及在每层的支撑上焊接防护构件等。挖掘与侧向承托图则应包括风险缓解措施的详尽资料、详细的施工程序及具体的地盘监督要求。

3.7.3 Robust risk mitigation measures could be provided as an alternative to the progressive failure check. These could include strengthening of plant/equipment control mechanisms such as provision of a distance detection sensor on the arm and rear of backhoes to prevent impact on the structural supports, welding of protective elements to the supports at all levels, etc. The ELS plans should include details of the risk mitigation measures, a detailed sequence of works and the specific site supervision requirements.

3.7.4 可使用没有加入系数的土壤强度参数和1.0的荷载系数进行渐进性破坏检查，而有关意外荷载的要求，应参考CIRIAC580报告。

3.7.4 Unfactored soil parameters and unity load factors may be used for checking against progressive failure. Reference should be made to the CIRIA Report No. C580 for the accidental load case.

3.8 表现检讨报告

3.8 Performance Review

3.8.1 当挖掘与侧向承托工程完工后，应呈交一份表现检讨报告（见《认可人士、注册结构工程师及注册岩土工程师作业备考》APP-115）。表现检讨报告可包括简要的工程设计检讨和工程表现报告，以及地盘监督人员（即董事级地盘监督(DSS)或适任技术人员(TCP)T5）在工程进行时定期提交的报告。

3.8.1 A performance review (see PNAP APP-115) should be submitted upon completion of the ELS works. It could comprise a brief review of the design and performance of the works and a list of regular reports submitted by site supervision staff (DSS or TCP T5) during construction.

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