崇明越江隧道岩土工程概要

对上海崇明越江隧道工程沿线的工程地质和水文地质条件进行概略总结,并对场地内的不良地质及其对策进行了分析评价。     

盾构隧道与矿山法隧道接合部施工工艺

深圳地铁2号线蛇海区间采用盾构法＋矿山法施工,但由于受地层及周边环境的限制,隧道接合部难以按原设计进行施工。经过研究比对,实际施工时采用了一种新的施工工艺,问题得以顺利解决,可供类似工程参考。     

云南安楚高速公路大红田隧道涌水分析

依据大红田隧道水文地质勘察和监测数据,结合前人已有成果,重点探讨隧道涌水特征、涌水影响范围及地下水消失量,并尝试对断流泉出流进行预测。     

隧道GPS施工控制网的建立

利用GPS定位技术建立隧道施工控制网,测量速度快、效益显著、精度高、成果可靠,宜于推广和应用。本文介绍隧道GPS施工控制网布网设计、观测设计、外业测量、数据处理后的结果精度和GPS测量的体会等。     

隧道工程地质预报方法探讨

本文从一些隧道工程事故实例出发，讨论了引起坍方和涌水灾害的工程、水文地质条件，不同工程阶段的预报方法以及预报研究的重大经济效益。最后提出五点提高预报符合率的原则和方法。     

A theoretical study of reinforcement influence on the stability of a tunnel face

Summary The problem of tunnel face stability is studied and the analysis of the stabilizing effect achieved by pre-reinforcement of the core which has to be excavated is dealt with. In Italy, the insertion of longitudinal fibreglass pipes in the ground has proved to be efficient in solving face instability problems. A thorough review of other applications of the technology has been carried out.The results of a series of parametric, three-dimensional, elasto-plastic finite element analyses are presented. The tunnel excavation with or without support and face reinforcement is simulated in the models. The stresses, plastic zones and displacements in the ground, pipes and lining have been studied. The support effect of the pipes is demonstrated by the results. Face reinforcement significantly reduces the displacements of the face. The stresses in the material at the face are also charged from tension to compression, thus enhancing face stability.     

What is the contribution of time-dependent deformation in tunnel convergence?

Tunnel excavation produces stress changes to the ground and strain to the support lining, leading to the closure (convergence) or instability of the excavated area. Convergence recorded after section excavation is assigned to: (i) strain resulting from the progressive tunnel front advance (face advance effect) and (ii) the time-dependent properties of the soil material (ground creep effect). In the present study, based on the geodetic monitoring records of two recent road tunnels in Greece, a simple methodology to estimate the contribution of each of the two effects is presented. Our analysis reveals that at least half of the total deformation of the examined tunnel sections is due to ground creep, indicating that the major portion of tunnel deformation is due to the time-dependent properties of the ground; a result supported by previous studies from other tunnels as well.     

Thermohydromechanical simulations of the natural cooling stage of the Tunnel Sealing Experiment

The Tunnel Sealing Experiment (TSX), located on the 420 Level of the Underground Research Laboratory (URL) of Atomic Energy of Canada Limited (AECL), was used to study the behaviour of two bulkheads installed in situ: one composed of highly compacted bentonite-sand blocks, the other composed of low-heat high-performance concrete. Permeable sand was placed in an 11.2-m-long chamber between the bulkheads. The chamber was first pressurized with water to 4 MPa to simulate the conditions likely to develop in the period following installation of seals in an actual repository. A stage of circulating hot water in the chamber began on 2002 September 24. The maximum design temperature of 85 °C at the interior face of the bulkheads could not be achieved in the time available. The actual maximum temperature was 65 °C. The purpose of heating was to investigate the thermohydromechanical responses in the bulkheads and surrounding rock to increased temperature. A passive cooling stage followed the heating stage. To help understand the influence of natural cooling on the thermohydromechanical response, a series of coupled thermohydromechanical modelling exercises was carried out using the finite element program, Model Of Transport In Fractured/porous media (MOTIF), and the results were compared with measured data. The thermal response in the rock and the bulkheads was successfully simulated. The influence of hydraulic conductivity on the hydraulic response in the clay bulkhead was analyzed.     

基于BOTDR的白泥井3号隧道拱圈变形监测

白泥井3号隧道是一条山岭隧道,隧道出口段位于滑坡等地质灾害多发的危险区域,为了确保隧道安全,应用国际上先进的BOTDR分布式应变测量技术,对隧道拱圈截面变形进行了分布式应变监测。本文着重介绍了BOTDR在隧道内安装布设以及监测数据的分析过程,监测成果显示,在将近1 a的监测时间里,隧道拱圈基本保持稳定,只是在个别区域,如K84+508.2处拱圈截面的衬砌表面发生张拉变形,变形量在雨季期间达到最大,据分析是由于雨水入渗山体造成围岩压力增大,致使拱圈截面受挤压变形。     

Numerical study of the performance of tunnel plugs

High axial flow rates within and along tunnels, excavated for deposition of high level nuclear waste, may increase the transport capacity of potential escape routes for radionuclides that have been released to the buffer surrounding the waste canisters, or to the tunnel backfill materials, from leaking fuel canisters. High flow rates may be found if the tunnel interior has a high permeability, either initially due to the composition of the backfill material or at later times due to degradation of low permeability backfill material components. If a disturbed rock zone, a DRZ, of increased permeability was created as a result of direct damage done to the wall region during tunnel excavation, this zone may contain additional possible escape routes. Low-permeability tunnel plugs, keyed into slots cut in the rock walls, have been suggested as means of reducing axial flow rates. This paper deals with different aspects of such tunnel-plug systems. A preliminary estimate of the potential for tunnel plugs to reduce axial flow rates is made using analytical expressions. A number of numerical techniques are employed to investigate the hydraulic, mechanical and hydromechanical performance. These include μFLOW (FEM flow calculations), FLAC (finite difference mechanical calculations) and 3DEC (distinct element mechanical calculations). The mechanical calculations concern the mechanical stability in the rock surrounding the slot and permeability changes in that rock caused by stress redistribution. The results show that the effects of tunnel plugs are very significant in most cases. A discussion on the validity of the results and the applicability of the used methods is provided.