穿越走滑断层的山岭隧道抗错断铰接设计试验研究

我国西部地区的长大山岭隧道在选线时多要穿越活动断裂带,面临断层运动对结构设计和安全运行的挑战。该文以滇中引水工程香炉山隧洞为工程背景,基于自主设计的用于模拟走滑断层运动的试验装置,研究走滑断层运动下岩体的破裂特性以及采用铰接设计的隧道模型的响应规律和破坏模式。试验结果表明：走滑断层运动下岩体地表位移在断层滑动面处存在明显的不连续;隧道与断层滑动面相交的节段衬砌横截面由圆形变为竖椭圆,且在给定50mm的断层错动量下水平轴直径变形率达到6.57%;隧道与断层滑动面相交节段衬砌在断层运动下产生约5°的水平偏转,且与相邻节段衬砌间有明显错台发生;与连续隧道相比,铰接设计可以显著降低衬砌结构的应变响应。此外,铰接体系隧道的破坏模式以环向裂缝和斜裂缝为主,在破坏程度和范围上均明显减小。     

基于能量守恒原理的跨活动断层隧道抗#br# 错断设计方法研究

强震区跨活动断层隧道科学设计与合理设防是一个难点,为此基于能量守恒原理,对断层错动作用下隧道的抗错断设计方法进行研究。通过对隧道破坏过程的能量分析,获得隧道结构的可释放应变能理论公式;提出跨活动断层隧道的抗错断设计思路,并建立设计方法;经实例应用并结合数值仿真验算,运用设计方法所得隧道结构的最小安全系数较规范值大18.5%,这说明所建立的设计方法可用于跨活动断层隧道的抗错断设防设计,并偏于保守。研究成果可为高烈度艰险山区跨活动断层隧道抗错断性能的提升提供参考。     

Three-dimensional finite difference analysis of shallow sprayed concrete tunnels crossing a reverse fault or a normal fault: A parametric study

Urban tunnels crossing faults are always at the risk of severe damages. In this paper, the effects of a reverse and a normal fault movement on a transversely crossing shallow shotcreted tunnel are investigated by 3D finite difference analysis. After verifying the accuracy of the numerical simulation predictions with the centrifuge physical model results, a parametric study is then conducted. That is, the effects of various parameters such as the sprayed concrete thickness, the geo-mechanical properties of soil, the tunnel depth, and the fault plane dip angle are studied on the displacements of the ground surface and the tunnel structure, and on the plastic strains of the soil mass around tunnel. The results of each case of reverse and normal faulting are independently discussed and then compared with each other. It is obtained that deeper tunnels show greater displacements for both types of faulting.     

Mud inrush flow mechanisms: a case study in a water-rich fault tunnel

Bulletin of Engineering Geology and the Environment - Fifteen serious inrushing disasters caused by mud flow occurred in the excavation of Yonglian Tunnel with a length of 2500 m in the...     

分布式光纤光栅传感监测在盾构穿越蓄水库中的应用研究

由于蓄水库的特性,使用传统方法直接监测底板、侧壁的开裂和渗漏情况短期内往往无法满足监测的时效性、准确性和分布性要求。本文采用分布式光纤光栅传感器进行盾构穿越期间蓄水库侧壁应变的不间断监测,并对监测结果进行分析,为盾构穿越既有构筑物提供一种实时可靠的监测方法,为盾构施工安全提供保障。     

Deformation control method of a large cross-section tunnel overlaid by a soft-plastic loess layer: a case study

This paper presents a case study of a large cross-section high-speed railway tunnel overlaid by a Q₂ soft-plastic loess layer. Due to poor engineering properties of the soft-plastic loess, two unexpected collapses occurred. This indicates that there is great difficulty and risk during tunneling. In this paper, the deformation control methods are studied by carrying out a series of numerical simulations and then validating via field tests. The stress and seepage coupling equations are deducted to embed into a 3D fluid-mechanical coupled numerical analysis. The results show that the curtain grouting scheme can effectively control the deformation of surrounding rock, and the real field data of settlement and horizontal convergence are 152 mm and 37 mm, respectively. However, the tunneling advance rate is slow (0.6 m/day) in trial sections because of the mutual interference between construction procedures. It can be used as an alternative scheme for lager deformation. The advanced drainage scheme can lower the ground water table below the excavation outline. The average water content of soft-plastic loess decreases from 26 to 22%, and the state of surrounding rock changes from soft plastic to hard plastic. The in situ settlement and horizontal convergence are 165 mm and 51 mm, respectively. Finally, it is proposed to use advanced drainage in combination with advanced small pipe grouting as a follow-up construction scheme. The successful completion of the whole tunnel proved the effectiveness of the proposed method.

     

Stability analysis of tunnel keyblock: a case study

The probabilistic block theory which was suggested by Hatzor and Goodman (1992) was applied to an telecommunication tunnel by taking into consideration the individual joints obtained from face mapping during tunnel construction. Using the actual unrolled joint trace that was developed in the Banpo telecommunication tunnel during tunnelling, a statistical analysis of observed discontinuity data was performed. The deterministic analysis and probabilistic keyblock concept were applied and their results were compared with the observed failure modes. The result obtained from the deterministic analysis resulted in a large difference compared with the observed failure pattern; the analysis method which considers the joint combination probability gave more similar results to the observed data than the deterministic analysis. Furthemore, individual keyblock analysis was performed by means of the newly developed program. While the positions of the keyblocks were predicted properly by the individual keyblock analysis, the predicted sizes of the keyblocks were found to be different from the observed data. It was acknowledged from the individual keyblock analysis that most keyblocks are composed of steeply inclined joints in the crown or in the side wall fo a tunnel. But, in the fault-zone, any method based upon the block theory could not predict the failure pattern properly. It can be concluded that the continuous careful investigations of geological conditions were very important in tunnelling through a rock mass that experiences mainly structure-induced failures.     

情景案例教学法在施工组织设计中的应用和研究

阐述了情景案例教学法的特点,教学中将案例前置,选取某校建筑物的施工组织设计作为案例,按照建筑工程施工组织顺序,重构课程体系,并以实际施工中典型工作场景和岗位要求为情景模拟对象,在案例背景中穿插情景教学,从而激发学生的学习兴趣,克服学习疲态,提高学习效率。     

Analytical approach for the design of active grouted rockbolts in tunnel stability based on convergence-confinement method

Assuming that grouted rockbolts increase internal pressure within a broken rock mass, a new procedure for computation of ground response curves for a tunnel reinforced with active grouted rockbolts is presented, while the effect of distance of bolted section to tunnel face has been also considered. This analytical solution for a circular underground excavation under hydrostatic stress field, and with consideration of a non-linear strength criterion for rock mass and on the basis of two material behavior models has been developed. In this work, the equation of the ground response curve for a tunnel which has been reinforced with passive grouted rockbolts is also derived. The proposed model allows one to take, the effect of the distance of the bolted section to the tunnel face, the effect of increasing rockbolts spacing, the influence of increasing pretension load in calculating of the ground response curve, and the effect of increasing the cross-section area of rockbolts, into account. The results show that decreasing rockbolts spacing increase the support system stiffness rather than preloading of them.     

地铁隧道盾构法施工安全风险评估研究综述

阐述了在地铁盾构法施工中进行安全风险评估的现实意义和社会意义,并在地铁盾构法施工的特殊性基础上,对国内外有关风险理论和动态风险管理等研究现状进行了系统总结,指出了在地铁隧道盾构法施工中现阶段风险评估的应用存在的主要问题和面临的难点。     

Classification of geological and engineering properties in weak rock: a case study of a tunnel in a fault zone in southeastern Korea

Given that the rock mass classifications of weak rocks observed in tunnels are evaluated only as ‘poor rock mass’ or grades IV–V using existing rock mass classification methods, a new scheme is needed that would better distinguish the various geological properties of weak rocks. In this study, geological and engineering properties of weak rocks were classified based on the analysis results of a total of 55 faces in a tunnel that passes through a fault zone in southeastern South Korea. Geological observations, point load tests, and Schmidt hammer tests were conducted to analyze the properties of the weak rocks. Through this analysis, the weak rocks were classified into two weathering types: ‘disintegrated rocks’ and ‘decomposed rocks’. This division is based on the tectonic mechanisms and parameters necessary to determine the engineering geological properties of individual rock-weathering types according to their geological properties. The ‘disintegrated rocks’ have been physically weathered by brittle deformation and are classified into three subtypes using the rock quality designation (RQD) and joint set number (J_n), which can characterize the discontinuity properties of the rocks. Point load tests were conducted on these individual subtypes to calculate the point load index (Is₍₅₀₎). The resultant values are clearly related to the assigned three subtypes. The ‘decomposed rocks’ have been chemically weathered by ductile deformation and are classified into five subtypes based on the results of Schmidt hammer tests conducted on faces and Is₍₅₀₎ values calculated using the average of the Schmidt hammer values. The geological properties of the individual subtypes of the ‘disintegrated rocks’ and ‘decomposed rocks’ are clearly related to their engineering properties. Based on these results, rock mass classification diagrams are proposed that can be simply and easily applied to weak rocks.

     

Application of the comprehensive forecast system for water-bearing structures in a karst tunnel: a case study

Bulletin of Engineering Geology and the Environment - While tunneling in karst terrains, engineers may encounter unpredictable well-developed karst conduits, which frequently lead to water inrush...     

Reflections on Bayesian Network models for road tunnel safety design: A case study from Norway

Directive 2004/54/EC from the European Parliament states that all EU member states should have well defined methodologies for risk analysis. This means that decisions regarding the design of road tunnels must be supported by risk information. TRANSIT, a Bayesian Network (BN) model for conducting quantitative road tunnel risk assessments has been developed to comply with the requirements. The developers of TRANSIT claim that their model represents best practice for risk assessments of road tunnels. This article explores the foundation for this claim. Furthermore, we assess TRANSIT as a tool for decision support regarding the design of new and novel road tunnel designs. The interactions between TRANSIT and the engineering environment and between risk analysts and responsible decision makers are studied by analyzing the engineering process of the 25 km Rogfast subsea road tunnel project in Norway.Our analysis shows that TRANSIT could be a useful tool in combination with other risk assessment activities. We also find that the model has severe limitations, especially when used for novel tunnel design projects such as Rogfast. First, the model applies a definition of risk that in most cases fails to provide an adequate risk picture, and hence fails to communicate risk to important stakeholders. Second, both data and models are rigid and presented to the users as a “black box”. This poses challenges with regard to the ownership of the analysis results and the responsibility for decisions made on the basis of the model, i.e., the relationship between the developer/owner and the analysts. Third, a standardized model will lead to standardized problems and solutions, which means that the results obtained from TRANSIT will be predictable when some experience with the model is gathered. In this way the model will preserve existing design and not promote innovation with regards to traffic safety designs. Fourth, the model emphasizes key performance indicators such as average annual daily traffic (AADT), tunnel length and curvature, while causes found in accident reports such as driving behavior, latent conditions and organizational and managerial factors may be neglected in the design process.     

案例分析之一：某中亚国家地铁项目

本文应用上期文章所提出的对外承包工程案例分析框架,介绍了中国某央企集团公司在某中亚国家以交钥匙总承包方式承建的地铁机电系统项目,这是我国建国至今最大的综合性民用机电出口建设安装项目之一,也是中国企业第一次涉足国际轨道交通工程承包市场.文章对该项目的特点和难点以及项目管理涉及的方方面面进行了详细论述,在此基础上对项目实施情况和效益进行了评价,并分析了项目的成败得失.     

基于iS3平台的隧道工程数据融合分析方法与案例研究

针对目前隧道工程数字模型中地质数据、工况数据和监测数据缺失,以及数字模型与数值分析程序难以自动对接的问题,基于iS3平台提出了结合隧道工程数字模型与勘察、施工和监测全过程数据的无缝融合方法,实现隧道工程多源、异构数据的可视化高效管理,并为自动化数值分析奠定基础。基于此数据融合方法,对海口文明东越江隧道各类型的数字模型进行搭建,可实现项目工程计划的动态调整。研发与工程信息管理平台相关联的工程二维数值计算的自动建模程序,将其作为平台的工具模块并进一步扩展功能,可将计算结果数据接入平台中,并实现计算结果的自动绘制。通过将该程序部署在该工程中,完成勘察、设计、施工、力学等多源异构数据的融合,最终实现工程的自动化数值分析,提升工程的数字数值一体化水平。     

Effects of structural planes on rockburst position with respect to tunnel cross-sections: a case study involving a railway tunnel in China

Uncertainty in the locations where rockbursts may occur with respect to a tunnel cross-section greatly increases the difficulty in monitoring and providing warnings of rockbursts and mitigating their effects. In this paper, we analyze the characteristics of 40 rockbursts that occurred in a railway tunnel in China. The rockbursts are divided into three cases depending on their position with respect to the tunnel cross-section and the prevailing geological conditions. An in situ microseismic (MS) monitoring system was established to determine the likely position of rockbursts with respect to tunnel cross-sections. The spatiotemporal evolution of the MS events that occurred during the development of rockbursts belonging to the three cases was subsequently obtained. The mechanism responsible for the changing positions of rockbursts with respect to tunnel cross-sections was further elucidated by analyzing the fracture type of the MS events and conducting numerical simulations using three-dimensional distinct element code (3DEC). Finally, support schemes, based on the monitoring and simulation results, are suggested.

     

A case study of seismic forward prospecting based on the tunnel seismic while drilling and active seismic methods

Bulletin of Engineering Geology and the Environment - Forward prospecting to predict the location of high-risk geological zones during tunnel boring machine (TBM) tunneling is important for safe...     

Deformational responses of operated shield tunnel to extreme surcharge: a case study

A field case of operated shield tunnel disrupted by unexpected extreme surcharge in Shanghai is reported in this paper. The deformational responses of segmental lining, in terms of convergences, settlements and joint open width, are highlighted. The surcharge caused by unexpected dumped soils with a maximum height of 7 m is six times larger than the design value of surcharge. Three hundred and sixty segmental lining rings of the operated metro shield tunnel below this surcharge are severely affected. The measured horizontal convergence to outer-diameter ratio (ΔD/D_out) ranges from 16.6 to 35.7‰, which is far beyond the averaged value for normal condition, i.e. 5.1‰. The trend of tunnel deformation (e.g. horizontal convergence and settlement) varying with surcharge level is found to be significantly non-linear. Correspondingly, the longitudinal joints are also severely disrupted and have large open widths. The rubber packer for joint near-tunnel springline loses its function of waterproof due to the release of 6 mm pre-compressive deformation. The majority of steel bolts of joint near-tunnel crown have passed yield state, while some are fractured. However, the circumferential joints are found to be in a sound workability.     

盾构隧道中心线坐标计算及程序设计方法研究

根据盾构隧道的线路形式（竖曲线和平曲线），给出了计算线路的中心三维坐标方法和程序设计步骤，具有一定的参考价值。