A multi-dimensional approach to the assessment of tunnel excavation methods

Selection of tunnel excavation method in rock calls for an exact assessment of engineering geology as well as geotechnical conditions of the tunnel strike. Moreover, uncertainties related to properties of engineering geology of rock often trigger complexity. In order to select the best possible excavation technique, one needs to take into account numerous operational, economic, environmental factors, and so forth. Using a hybrid methodology, including multiple attributes decision-making techniques and fuzzy set theory, the present study aims to evaluate the excavation methods of tunnels. The proposed approach is based on fuzzy-AHP and TOPSIS methods where the fuzzy-AHP determines weights of the criteria by decision makers in uncertain environment and TOPSIS concludes rankings of the excavation methods. Finally, a case study of Ghomroud project in Iran is presented to demonstrate the result of the proposed methodology.     

An integrated multiscale approach for characterization of rock masses subjected to tunnel excavation

The design of tunnels must be conducted based on the knowledge of the territory. The longer the structure, the larger the area to be investigated, and the greater the number of surveys and tests to be performed in order to thoroughly examine all the relevant features. Therefore, optimization of the investigation process is strongly required to obtain complete and reliable data for the design of the infrastructure. The fast development of remote sensing technologies and the affordability of their products have contributed to proving their benefits as supports for investigation, encouraging the spreading of automatic or semi-automatic methods for regional scale surveys. Similarly, considering the scale of the rock outcrop, photogrammetric and laser scanner techniques are well-established techniques for representing geometrical features of rock masses, and the benefits of non-contact surveys in terms of safety and time consumption are acknowledged. Unfortunately, in most cases, data obtained at different scales of investigations are only partially integrated or compared, probably due to the missing exchange of knowledge among experts of different fields (e.g. geologists and geotechnical engineers). The authors, after experiencing such a lack of connection among the results of different surveys concerning tunnels, propose a multiscale approach for the optimization of the investigation process, starting from the regional scale, to obtain the data that can be useful not only for planning more detailed surveys in a preliminary phase, but also for making previsions on the discontinuity sets that are present in the rock masses subjected to excavations. A methodological process is proposed and illustrated by means of a case study. Preliminary results are discussed to highlight the potentiality of this method and its limitations.     

基于FLAC3D的隧道分台阶开挖数值模拟与分析

基于有限差分法的FLAC3D数值模拟,对隧道的分台阶开挖进行了计算与分析,研究了隧道开挖过程中的位移变化和稳定状态,提出了相应的预防措施和建议,分析结果为隧道施工控制提供了理论支持。     

余家（齐耀山）隧道岩溶处理技术

以新建铁路重庆至利川线余家（齐耀山）隧道岩溶处治技术为例,针对不同岩溶类型洞穴提出了相应的解决措施,可指导今后类似工程的隧道施工。该隧道溶洞（暗河）数目众多、施工地质复杂,施工经验表明：综合地质超前预报结果对不同类型岩溶进行处理,及岩溶隧道风险管理等关键技术,为隧道的成功建设发挥了重要作用。     

隧洞开挖数值模拟及运用

介绍了隧洞开挖中空间效应在平面问题中的模拟方法——应力释放法,及该法在岩土软件FLAC-3D中的实现方式,结合某水工隧洞开挖的实际工程,模拟了水工隧洞的分步开挖过程,分析了在考虑空间效应情况下的计算结果,说明在隧洞开挖平面模拟过程中考虑空间效应的必要性,表明了岩土软件FLAC-3D在水工隧洞开挖模拟中具有较强的适应性。     

盖挖逆作地下结构工程施工缝防水处理方法

针对盖挖逆作地下结构工程施工缝防水施工的重要性进行了简要分析,详细介绍了钢边止水带、遇水膨胀止水胶及可维护注浆管等常见做法的材质性能、适用范围、安装方法,并总结了相应的施工控制要点,为今后同类工程施工提供了指导。     

小净距隧道开挖工艺对围岩稳定性的影响

为研究小净距隧道的不同开挖工艺对围岩稳定性的影响,对重庆花土岗隧道分别利用全断面法、上下台阶法和单侧壁导坑法进行了开挖有限元数值模拟,分析了小净距隧道不同施工方法对洞周围岩稳定性的影响.结果表明:全断面法对隧道围岩及中夹岩柱的水平位移和应力影响较大;上下台阶法和单侧壁导坑法影响相对较小.施工中应根据实际情况选择合理的开挖方法,及时施作支护并加强监测,保证施工质量.本文的分析方法和计算结果对小净距隧道设计、施工具有一定的参考价值.     

An approach for wellbore failure analysis using rock cavings and image processing

There have been interests to link different cuttings/cavings to various wellbore failure types during drilling. This concept is essential when caliper and image logs are not available. Identification of wellbore failure during drilling gives more chance of immediate actions before wireline logging program. In this paper, an approach was presented based on the image processing of ditch cuttings. This approach uses the sphericity and roundness of cuttings as input data to classify caving types and subsequently determine the dominant failure type. Likewise, common definitions of cavings were discussed initially before a new criterion is suggested. This quantitative criterion was examined by observations from caliper and acoustic image logs as well. The proposed approach and criterion were implemented on ditch cuttings taken from a well in Western Australia. Results indicate that the primary failure is shear failure (breakout) due to high levels of angular cavings. However, another failure due to the fluid invasion into pre-existing fractures was also recorded by blocky cavings.     

基于图像处理的混凝控制方法研究

根据絮体等效直径与沉淀出水浊度具有很好的相关性这一特征,采用计算机实时采集和图像处理的方法对絮体图像进行定量分析得到等效直径,并将其作为控制混凝剂加注量的目标值,实现水处理过程中混凝剂添加的自动控制。     

基于数字图像的非均质岩土工程材料的数值分析方法

提出了一种基于数字图像的非均质岩土工程结构的二维数值分析方法。以花岗岩为例,先将岩石的表面图像导入计算机中;然后采用基于彩色空间的数字图像技术将组成花岗岩的几种主要材料:长石、石英和黑云母一一分辨出来并再现岩石的细观结构;再通过一个简单的线性转换,将图像细观结构转换为矢量细观结构;最后,岩石的矢量细观结构可以与数值计算方法--有限元法或有限差分法结合,从而实现非均质岩石材料的力学分析。采用有限差分法FLAC程序来分析岩石的破坏过程。传统室内试验数值模拟表明材料的细观结构对应力分布和破坏模式有着明显的影响,基于数字图像的数值分析方法可以真实地实现岩土工程材料的非均质分析。     

A novel image-based approach for interactive characterization of rock fracture spacing in a tunnel face

This paper presents a novel integrated method for interactive characterization of fracture spacing in rock tunnel sections. The main procedure includes four steps:(1) Automatic extraction of fracture traces,(2)digitization of trace maps,(3) disconnection and grouping of traces, and(4) interactive measurement of fracture set spacing, total spacing, and surface rock quality designation(S-RQD) value. To evaluate the performance of the proposed method, sample images were obtained by employing a phot...     

三维数字航道的设计与实现

针对我国内河航道水深季节变化大、航行安全要求高的特点,本文运用虚拟现实、三维地理信息系统、计算机图形图像处理等技术,对三维航道数据库、水下地形建模及疏浚分析、水体可视化、实时水位可视化、航标建模及可视化等关键技术进行攻关,并以长江重庆航道示范段为例,建立三维数字航道系统,支持实时航标、船舶、水位信息集成。本文在推进航道精细化管理、增强水上安全方面具有重要作用。     

深基坑开挖与邻近隧道相互影响的分析

采用三维快速拉格朗日方法(FLAC3D)模拟软土地区深基坑的分步开挖和支护过程。根据隧道与基坑不同位置关系,分为"紧贴型"和"浅埋型"两类、共7种工况,分析基坑分步开挖对邻近地铁隧道变形的影响以及隧道对基坑连续墙变形和墙后地表位移的影响。数值分析土体采用修正剑桥模型,考虑了连续墙和土体的接触滑移作用。数值分析结果发现隧道变形大小与基坑距离关系并不完全单调,隧道的存在对基坑墙后土体有明显的"加筋效应"。     

Probabilistic assessment of tunnel construction performance based on data

A probabilistic model for estimating tunnel construction time is learnt with data from past tunnel projects. The model is based on the Dynamic Bayesian Network technique. The model inputs are determined through an analysis of data from three tunnels built by means of the conventional tunneling method. The data motivate the development of a novel probability distribution to describe the excavation performance. In addition, the probability of construction failure events and the delay caused by such failures are estimated using databases available in the literature. The model is applied to a case study, in which it is demonstrated how observations from the tunnel construction process can be included to continuously update the prediction of construction time.     

三轴土样局部变形的数字图像测量方法

在已完成的土样径向变形数字图像测量基础上 ,实现了土样轴向变形和径向变形的同步测量 ,不仅可测量土样整体的平均变形 ,而且可测量土样的局部变形 ,还给出了图像测量系统的理论精度和实际测量精度。用砂土、粉煤灰两种饱和试样进行固结排水剪切试验 ,对采用图像测量方法得到的三轴土样不同部位的局部测量结果和采用传统测量方法得到的整体平均测量结果进行了比较     

基于数字图像处理技术的金相分析

随着计算机技术的发展,数字图像处理技术也得到了快速的发展,将数字图像处理技术应用到金相分析中,提取金相照片中的典型结构特征,帮助火调人员对金相图片分类,协助调查火灾原因及火灾蔓延方式,为火灾调查提供迅速有效的科学信息.     

Monitoring tunnel deformations by means of multi-epoch dispersed 3D LiDAR point clouds: An improved approach

Monitoring tunnel deformations is a crucial task when evaluating tunnel stability and safety. This task requires an accurate and high-resolution spatial technique to precisely capture the meticulous anomalies on a tunnel surface. As a response, the light detection and ranging (LiDAR) technique, which collects detailed spatial data in a fast and automatic manner, was recently proposed by Han et al. (2013) for monitoring the deformation of a 2D tunnel profile. Although the proposed approach successfully uses this modern spatial technique in tunnel analysis, the benefits of the 3D LiDAR technique have not been fully exposed. This study improved the technique as a real 3D approach. The associated uncertainties can be reduced by avoiding the 3D to 2D profile projection step. The minimum-distance projection (MDP) was then estimated using directly the 3D dispersed point clouds so that any deformation signal (point displacement) along the entire tunnel surface can be immediately identified. Furthermore, a rigorous covariance propagation approach was introduced to provide explicit quality indications on the obtained solution. The results of simulation tests and a real case study of a highway tunnel showed that the spatial implications of the 3D LiDAR technique can be fully explored by implementing the improved approach. Consequently, a more accurate and comprehensive solution for monitoring tunnel deformations can be achieved.     

三轴试验土样径向变形的计算机图像测量

提出了一种三轴土样径向变形的计算机数字图像测量方法。将计算机图像识别技术应用于常规的土工三轴试验 ,实现三轴土样变形的直接测量和土样变形过程的摄像、自动测读和自动记录 ,不仅为土工三轴试验提供了一种直接、有效的测量手段 ,而且可以把常规三轴仪应用于非饱和土的变形测试。文中还分析了测量精度和测量误差产生的原因。给出了对于实际土样采用常规测量方法和数字图像测量方法测量结果的比较。     

关岭隧道全断面开挖光面爆破施工技术

以西汉高速公路关岭隧道为例,从隧道全断面开挖光面爆破特点、各种参数的确定、施工方法、适用范围、实施效果等方面进行论述,希与正在采用或对隧道全断面开挖光面爆破感兴趣的同仁一起探讨研究.