Numerical modelling of in situ behaviour of the Callovo–Oxfordian argillite subjected to the thermal loading

To enhance the understanding of thermal impact on the in situ behaviour of the Callovo–Oxfordian argillite, this paper presents an interpretation of an in situ heating experiment carried out in the Meuse/Haute Marne Underground Research Laboratory (M/HM URL). The argillite was heated successively by two constant heating powers: 277 W and 925 W. When subjected to thermal loading, the argillite exhibits an important volume change and a strong pore pressure response that significantly affect its hydraulic and mechanical behaviour. Numerical analysis has been performed by using a coupled theoretical formulation that incorporates a constitutive model especially developed for this material. Based on Biot's theory, this model includes the influence of interstitial pressure on the mechanical behaviour. The simulation obtained reproduces satisfactorily the results of the in situ experiment and the main observed patterns of behaviour. The interpretation and discussion of numerical results provide additional data that can help us to understand the thermo-hydromechanical behaviour concepts of saturated argillite formation.     

临沂市地下空间开发利用现状及建议

随着城市化进程加快,城市建设需要更多的空间,开发利用城市地下空间已是首要解决的问题。近年来,面对用地供求矛盾日益加剧的严峻形势,临沂市积极转变发展理念,鼓励开发地下空间,建设公共设施、商业设施和文化娱乐设施,从单纯追求建筑高度和平面扩张,调整为协调推进空中、地上、地下开发的三维发展模式。该文以临沂市地下空间开发为例,系统分析开发模式、功能定位及利用现状,认为工作中缺乏整体规划,协调管理机制不健全,投资主体单一,提出了整合资源,严格执行规划,完善政策法规,出台优惠政策等对策建议,对破解城市发展用地难题,提高城市承载力具有一定借鉴作用。     

黄河三角洲南部冲洪积扇区地下淡水调蓄条件研究

黄河三角洲南部冲洪积扇区浅层地下水由于长期大量开发利用,早已形成了区域性漏斗群。通过对漏斗区地下水赋存条件和调蓄条件的分析,提出了由新建的引黄主干渠引黄河水,采用河渠、坑塘内施工回灌引渗,以及丰水期大气降水地表径流拦蓄引渗和引黄河水引渗回灌联合调度的方案,并从调蓄资源增量、调蓄可行性和调蓄效益等方面进行了论证。     

A 2.5D coupled FE-BE model for the prediction of railway induced vibrations

Ground vibrations induced by railway traffic at grade and in tunnels are often studied by means of two-and-half dimensional (2.5D) models that are based on a Fourier transform of the coordinate in the longitudinal direction of the track. In this paper, the need for 2.5D coupled finite element-boundary element models is demonstrated in two cases where the prediction of railway induced vibrations is considered. A recently proposed novel 2.5D methodology is used where the finite element method is combined with a boundary element method, based on a regularized boundary integral equation. In the formulation of the boundary integral equation, Green's functions of a layered elastic halfspace are used, so that no discretization of the free surface or the layer interfaces is required. In the first case, two alternative models for a ballasted track on an embankment are compared. In the first model, the ballast and the embankment are modelled as a continuum using 2.5D solid elements, whereas a simplified beam representation is adopted in the second model. The free field vibrations predicted by both models are compared to those measured during a passage of the TGVA at a site in Reugny (France). A very large difference is found for the free field response of both models that is due to the fact that the deformation of the cross section of the embankment is disregarded in the simplified representation. In the second case, the track and free field response due to a harmonic load in a tunnel embedded in a layered halfspace are considered. A simplified methodology based on the use of the full space Green's function in the tunnel–soil interaction problem is investigated. It is shown that the rigorous finite element-boundary element method is required when the distance between the tunnel and the free surface and the layer interfaces of the halfspace is small compared to the wavelength in the soil.     

地下连续墙钢筋笼安放施工技术

结合苏州工业园区南环快速路东延工程地下连续墙施工,叙述在保证吊装长大钢筋笼和接头桩的安全性、可靠性、使被吊物体不发生弹性变形和降低抗弯强度的情况下,选择起重设备、确定吊点位置、配备吊具,并介绍接头桩、钢筋笼的吊装过程及注意事项。     

某水电站地下洞室随机块体稳定性评价及系统锚固设计

地下洞室中的随机块体是指由岩体中的随机节理或者基体裂隙构成的不确定性块体 ,在已建的地下厂房中 ,这类块体大量存在 ,这类块体的稳定性会对洞室的施工安全造成较大的影响。在设计中这类块体常常是通过系统锚杆进行加固 ,但由于块体位置随机性和几何特征的不确定性 ,使得系统锚杆的长度和间距很难确定。本文以某水电站的地下洞室为研究对象 ,在深入了解地质条件、岩体结构特点的基础上 ,找出可能构成随机节理的分布规律 ,再分析节理与节理、节理和Ⅰ、Ⅱ类确定性结构面可能的组合 ,得到可能的随机块体 ,然后采用块体理论评价其稳定性 ,得到随机块体的几何特征和稳定状况 ,总结出最优的锚杆长度 ,为地下洞室的系统锚杆长度的确定提供了理论依据     

低地应力区碎裂结构围岩基本特征研究

以某市引水工程地下洞室围岩为例 ,采取试验样品若干件 ,分别做了围岩的平均化学成分与百分含量衍射以及电镜扫描分析 ,并得到了相应的结果。在此基础上 ,从成分和微观结构两方面入手 ,总结出低地应力区碎裂结构围岩组成与显微结构方面的特征和变化规律 ,初步探讨了低地应力区碎裂结构围岩微观变形特征 ,这为进一步研究低地应力区围岩宏观变形破坏及其稳定性等方面 ,将会起到重要的理论指导作用     

哈萨克斯坦扎尔干特-阿拉善30号井前兆异常特征

介绍了哈萨克斯坦扎尔干特阿拉善30号井的水文地球化学环境,对其15年来的交换资料进行了初步的统计与分析。结果表明,在震中距为300 km、400 km范围内,5级、6级地震的异常项目比例分别可达55.6%、61.1%,而7级大震(或6级震群)远兆的异常比例仅为16.7%。且在异常时间、异常形态上,5级、6级和7级地震(或6级震群)各有其特点和差异。     

哈萨克斯坦卡帕尔-阿拉善4号井前兆异常特征分析

选取距卡帕尔-阿拉善4号井300 km范围内的3次5级地震,400 km内的3次6级地震,约600 km内1次7级地震、1次6级强震群作为震例资料,分析了这些地震前卡帕尔-阿拉善4号井前兆异常特征。结果表明:①对于5级地震,50.0%测项出现前兆异常,水化学、水动态异常各占50.0%。这些异常的58.3%表现为中期异常,41.7%表现为短期异常,无单独临震异常,也无叠加临震异常。异常变化幅度大而明显,且以趋势性上升或下降为主。硅酸和硫酸根在同一地震前异常时间与异常形态相似。②对于6级地震,33.3%测项出现前兆异常,其中水化学异常占38.9%,水动态异常占16.7%。出现的异常57.1%为中期异常,28.6%为短期异常,14.3%为临震异常。异常形态多为脉冲突跳,而仅有少数为趋势性高值异常。各异常项目之间有一定的同步性。③对于7级地震或6级强震群,37.5%测项出现前兆异常。出现的异常83.3%为中期异常,16.7%为短期异常。异常幅度大而明显,异常形态以单值突跳或趋势性为主。     

地下采煤的缓倾边坡变形机制

通过某地边坡变形的环境条件和多年监测资料,提出地下采煤的缓倾边坡变形机制,即由地下采煤产生的岩层弯曲下沉侧推效应和央体松动扩容侧推效应,以及地下水作用产生的空隙水压效应导致的边坡变形,并对边坡变形机制进行了验证。