某基坑支护的施工设计及应急加固

在市区复杂的场地进行基坑开挖,需要对不同区段所采用的与该区段地质条件相适应的基坑支护形式进行详细设计。以某实际工程为例,介绍了一个多种支护型式的基坑的设计过程及出现位移过大时的加固措施。     

城市地下车站PBA工法扣拱施工技术

结合具体工程实例,介绍了PBA工法初支扣拱处理施工工艺和控制要点,着重阐述了土方开挖、冠梁施工、边导洞回填等关键工序施工步骤,为今后类似地下车站工程积累了宝贵经验。     

富水砂卵石隧道暗挖施工工艺

根据隧道地质情况，采用了暗挖法施工方案，详细介绍了富水流砂地段隧道暗挖施工工艺及控制要点，通过编制具有可操作性的施工方案、制定合理的施工工艺、合理安排施工工序，从而确保隧道施工安全，保证工程质量。     

富水粉细砂层小断面隧洞暗挖施工工艺研究

结合陕西省神木县应急供水工程输水隧洞地质情况,采用了暗挖法施工方案,详细介绍了富水粉细砂层隧洞暗挖施工工艺及控制要点,通过编制具有可操作性的施工方案、制定合理的施工工艺、合理安排施工工序,从而确保隧洞施工安全,保证工程质量。     

双排桩基坑支护在膨胀土地区的工程应用

以成都望江锦园工程为例,介绍了双排桩支护体系在深基坑支护中的应用,基坑侧壁的变形观测结果表明,双排悬臂桩支护能够有效控制基坑水平位移。     

Design of sequential excavation method for large span urban tunnels in soft ground – Niayesh tunnel

Modern tunnel design and construction requires appropriate techniques and technologies during all phases of a tunnel project. Selecting a suitable excavation procedure for large span urban tunnel projects in soft ground is a key factor for successful construction of the project. The costs and time for tunnel construction are strongly influenced by the choice of the excavation procedure. This research focuses on the selection of excavation method, excavation sequence and optimum trailing distance between different excavation stages in soft ground urban tunnelling. Considering soft ground condition and the big cross section of the Niayesh urban road tunnel project, sequential excavation method (SEM) was selected for tunnel construction. In this phase, Central Diaphragm (CD) and Side wall Drift (SD) methods were proposed for tunnel construction and appropriate method was selected based on its potential to limit surface settlements. Then, different excavation sequences considering side wall drift method were planned and modelled using three dimensional finite element method and optimal excavation sequence was selected. Finally, the trailing distance between different excavation stages were analysed numerically and the optimal distance with minimum surface settlement was determined.     

新奥法在金鸡岭隧道工程中的应用

本文简要介绍了新奥法的施工原理,以金鸡岭隧道工程为实例,根据实际工程地质情况阐述了隧道的开挖、超前支护、初期支护、二次衬砌及隧道监测的施工方法,合理地解决隧道施工中存在的问题,取得良好的经济和社会效益。     

Decision Support System for Waterproofing of Below-Grade Structures

Abstract:   This study focused on the development of a decision support system (DSS) for waterproofing of below-grade structures. The objective was to formulate an optimal solution for waterproofing of below-grade structures according to their parameters and based upon engineering and economic criteria. The model examines the environmental, structural, economic, and service life planning aspects of waterproofing in an integrated manner. The decision support model was based on the following four phases: input interface, preliminary classification, advanced classification, and output interface. The output phase consists of an interactive accessory that provides design details and quality assurance guidelines for each particular case, as well as economic parameters such as life cycle costs and risk of failure. The major contribution of this DSS is its development of a methodological application of integrated decision process, achieved by the use of engineering, economic, and service life criteria. Application of the DSS to several case studies revealed that a number of near-optimal alternatives exist, which differ from one another in terms of constructability, capital costs, and labor inputs. Cost of failure plays a major role in life cycle assessment, and may be a salient factor in the selection of the optimal solution.     

Finite element analysis of a deep excavation: A case study from the Bangkok MRT

The Bangkok metropolitan area, located on a thick river soft clay deposit, has recently started a construction project on a mass rapid transit underground railway (MRT). This paper presents a finite element study on the Bangkok MRT underground construction project. The excavation of Sukhumvit Station was selected as the case study for the FEM numerical modelling in this paper. The numerical study focuses on the initial input on the ground conditions and the constitutive soil models. The geotechnical parameters were selected based on the soil investigation reports carried out for the purpose of the construction. The parameters selected for the constitutive models used in the FEM analysis were calibrated against the laboratory testing results. Finally, all the FEM simulations were compared with the data from field investigations.     

LEARNING OUTCOMES FROM CONSTRUCTION SIMULATION MODELING

Repetitive construction processes exhibit improvement in production rate as repetitions increase. A learning curve can be developed for such construction processes that can improve the predictive accuracy for the early portions of project schedules. This paper discusses a method for incorporating learning development in a construction simulation model. The case study model represents the construction of a guide wall for a lock using a mobile cofferdam. The impact of including learning development on model results is reported as well as a sensitivity analysis.     

复杂地层地下连续墙施工实例分析

地下连续墙工法的广泛应用使得深基坑技术日益成熟,特别是在地质条件恶劣区域。以复杂地层情况下地下连续墙施工实例为背景,介绍地下连续墙施工过程中难点及注意事项。同时,在基坑开挖阶段对地下连续墙实时监测,对监测数据进行适当地处理,反映地下连续墙变形的实际情况。结合地下连续墙变形监测数据,表明该工法的应用效果良好,期望能对类似工程有一定的参考。     

Investigating key challenges in major public engineering projects by a network-theory based analysis of stakeholder concerns: A case study

The diversities of stakeholder concerns and intricate interdependencies between stakeholder concerns are important factors adding complexities to major public engineering projects (MEPs). Using case study and network-theory based analysis in a large reclamation project, this paper investigated the key stakeholder concerns and concern interdependencies of MEPs, and how they bring major challenges confronted by stakeholders. The network analysis identifies five major challenges of the case: “applying highly advanced and complex construction technology”, “mitigating project disruptions to the environment and marine ecology”, “conducting public and community consultation during construction phase”, “site constraints due to nearby air and marine traffic”, and “meeting government standard on the quality of new materials and equipment”. Recommendations are provided to alleviate these problems for future MEPs. This paper contributes to a new angle, the network perspective, of analyzing stakeholder concern interdependencies and their practical implications on MEPs. The findings provide useful insights on common pitfalls of MEPs.     

A case study on rock damage prediction and control method for underground tunnels subjected to adjacent excavation blasting

The effects of tunnel blast excavation on the surrounding rock mass and the lining systems of adjacent existing tunnels are comprehensively studied for the Damaoshan highway tunnel project as a case study. The damage of the surrounding rock and the lining system under different blast loads are analyzed by field tests and numerical simulations. It is observed that the rock damage extent around the tunnels linearly increases with the peak particle velocity (PPV) of the existing tunnel. A feasible PPV-based damage control method is then proposed for different portions of the tunnels. For the Damaoshan tunnel project, a PPV threshold of 0.22 m/s in the adjacent existing tunnel is prescribed to limit the damage extent to approximately 1.6 m at the tunnel exit and entrance portions. Furthermore, the PPV criteria for the other portions are also determined accordingly. It is also shown that no failure occurs in the linings or at the rock–lining interfaces if the PPV is less than 0.30 m/s. The control method and the threshold PPV proposed in this study have been successfully applied to restrict blast-induced damage during the new tunnel excavation of the Damaoshan tunnel project.     

杭州钱江新城地下连接工程暗挖施工技术

结合杭州钱江新城地下连接工程暗挖施工技术,阐述了在城市交通要道施工的条件下,粉砂土地层中,且管线保护要求很高的情况下,采用WSS全断面预注浆,大管棚支护CRD开挖法施工技术,成功地保证了施工的安全和顺利进行。     

浅埋暗挖法在供水管道安装工程中的应用

介绍了一种在特殊路段进行支管安装的浅埋暗挖施工方法.该法采用暗挖形成施工隧洞后,再在隧洞内进行管道安装,可替代明挖和项管施工方法.结合工程实例,介绍了浅埋暗挖施工工艺流程和主要技术特点.     

隧道施工明洞暗做具体运用实例

介绍了襄渝二线铁路胡安段XYS-02标段新砦沟隧道在现场实际施工中运用明洞暗做施工工艺,克服施工中客观存在的不利因素,确保施工安全和进度的具体运用实例,总结了在软弱薄上覆层地质条件下的暗挖施工特点和注意事项,得出了有益的经验结论。     

重叠隧道爆破振动对相邻结构的影响

以某地铁工程区间近距离重叠隧道为背景，研究地铁区间隧道施工期间，爆破荷载对相邻隧道结构的影响。首先根据爆破振动加速度波确定爆破振动荷载，然后采用释放荷载方法模拟地铁隧道的开挖效应，确定初始应力场并通过对土一地铁结构体系进行模态分析，得到体系的振型和频率，以确定合理的阻尼系数和时间积分步长。最后运用Newmark隐式时间积分法，研究地铁区间近距离重叠隧道的动力响应。确定了在爆破振动荷载作用下衬砌结构的薄弱部位及其相应的位移和应力，得到地表的振动参数及其衰减值。得出的结论对设计和施工具有一定的指导意义。     

软土地区某基坑失稳事故分析

主要介绍了上海地区某基坑工程失稳事故。水泥搅拌桩由于施工简便,经济性好等优点,在此工程中作为围护结构使用。但是由于施工场地不合理的堆载及其他一些因素导致基坑东北角水泥搅拌桩围护结构发生破坏。本文通过有限元软件对该事故进行分析,为今后的工程提供依据。     

Latest technology of underground rock cavern excavation in Japan

Four major projects with large-scale rock underground caverns are discussed in this report; two hydropower stations, one underground oil storage facility and one underground museum in Japan. The technology applied to the construction of these caverns have some unique characteristics and can be applied to various other underground uses for different purposes and applied to larger-scale underground rock caverns with different geological and in situ stress conditions. Generally, construction of an underground cavern is comprised of five major activities: geological investigation; cavern stability analysis; initial rock support design; excavation works; and redesign of rock support according to the observational construction method. Weighted factors allocated among these factors should be established based on the rock properties and the purpose of the underground cavern use, which would define the major characteristics of the construction project. This report discusses some of major characteristics of these projects in Japan.     

城市地下通道工程安全监测

结合地下通道工程基坑监测情况,介绍了监测技术在地下工程开挖过程中的应用,充分采用了信息化施工,详细分析了围护结构水平位移与垂直位移、周边建筑物沉降、路面沉降以及地下通道土压力的变化情况,通过对该工程安全监测进行研究,制定了严格的监测方案,有效的确保了施工的安全。