Numerical simulation study of the failure evolution process and failure mode of surrounding rock in deep soft rock roadways

Based on the safety coefficient method,which assigns rock failure criteria to calculate the rock mass unit,the safety coefficient contour of surrounding rock is plotted to judge the distribution form of the fractured zone in the roadway.This will provide the basis numerical simulation to calculate the surrounding rock fractured zone in a roadway.Using the single factor and multi-factor orthogonal test method,the evolution law of roadway surrounding rock displacements,plastic zone and stress distribution under different conditions is studied.It reveals the roadway surrounding rock burst evolution process,and obtains five kinds of failure modes in deep soft rock roadway.Using the fuzzy mathematics clustering analysis method,the deep soft surrounding rock failure model in Zhujixi mine can be classified and patterns recognized.Compared to the identification results and the results detected by geological radar of surrounding rock loose circle,the reliability of the results of the pattern recognition is verified and lays the foundations for the support design of deep soft rock roadways.     

砂井地基中的有限元方法及其应用研究

阐述了二维平面应变比奥固结理论及其具体的有限元格式,详细介绍了砂井地基的两类平面应变等效方法及其原理.结合江西城门山铜矿凤爪沟尾矿坝软基处理实践,采用了以修正剑桥本构关系为基础的渗流变形耦合模型对尾矿坝施工过程中的砂井地基固结情况进行了有限元数值模拟和预测,对有限元数值模拟结果进行了详细的分析,总结了砂井地基固结过程中的位移、孔隙水压力随时间的变化规律,并与现场监测结果进行了对比、分析.结果表明:实测期内,位移的模拟值及其发展规律与实测结果比较接近,本文所使用的有限元模拟方法可以用来预测砂井地基的固结过程.该数值分析对相类似的砂井地基软基处理工程实践具有一定的指导意义.     

接触带土层软化对排土场边坡稳定性的影响分析

针对排土场上部渣土层和下部基岩面接触处的软化接触带对其稳定性的影响问题,采用有限元极限分析法构建了含软化接触带的排土场边坡的数值模型,系统分析了堆填角度、基岩倾角、软化接触带厚度及软化度对排土场边坡稳定性的影响规律,并通过具体的排土场边坡实例验证了该分析方法的可行性。研究结果表明,同等条件下,接触带软化和堆填角度对排土场边坡稳定性的影响很大,而基岩倾角和接触带厚度的影响相对较小;随着接触带软化度的增大,排土场边坡下、上限安全系数的绝对衰减率可达50%左右;随着接触带土层的不断软化,排土场边坡滑动面穿过软化接触带的长度逐渐变大,滑坡总体积不断增大;因软化接触带土层的存在,排土场边坡中下部土体推挤坡脚前缘及牵引后部坡体滑动,最终形成由软化接触带到坡顶的贯通滑裂面。     

初始渗流场对渣土场边坡降雨入渗特征及其稳定性的影响

渣土场是容纳弃土和弃渣的主要场所,由于堆填材料和压实方法的差异性,研究初始渗流场对计算渣土场边坡的降雨入渗特征及其稳定性的影响具有现实意义.以深圳市部九窝渣土场边坡为研究对象,运用非饱和渗流原理和非饱和土强度理论建立数值计算模型,设计了不同初始渗流条件和不同降雨强度的计算方案,揭示了渣土场边坡在降雨作用下的渗流特征及其...     

松散堆积体围岩隧道施工方案对比分析

在某高速公路大型堆积体围岩隧道施工中出现了拱顶塌方、超前支护砸毁、二衬开裂现象,致使施工方案多次变更,为此,采用大型室内饱和固结排水剪试验获得堆积体力学参数,结合现场监测和设计方案,利用三维数值模拟方法模拟了上下台阶法、三台阶分步开挖法及单侧壁导坑法等方案施工过程,对各方案进行了对比分析.结果表明,单侧壁导坑施工方案能有效减小拱顶位移和塑性区的发展,二衬受力也相对合理,因此较适合松散堆积体围岩隧道.分析结果可为同类型松散堆积体围岩隧道施工和方案设计提供参考.     

基于ANSYS的阿海水电站碾压混凝土重力坝静动力分析

采用大型通用软件ANSYS,通过对阿海水电站碾压混凝土重力坝方案各坝段分别进行平面有限元静力和动力分析及静动结果叠加分析,探讨了坝体及基础在各种工况下的变形和应力规律,了解坝体和基岩在设计条件下的工作形态,对方案的可靠性进行了评价.     

Numerical analysis and geophysical monitoring for stability assessment of the Northwest tailings dam at Westwood Mine

The Westwood Mine aims to reuse the tailings storage facility #1(TSF #1) for solid waste storage, but,downstream of the Northwest dike is considered critical in terms of stability. This paper uses numerical modeling along with geophysical monitoring for assessing the Northwest dike stability during the restoration phase. The impact of waste rock deposition in the upstream TSF #1 is considered. The geophysical monitoring is based on electrical resistivity methods and was used to investigate the internal structure of the dike embankment in different deposition stages. The numerical simulations were performed with SLOPE/W code. The results show a factor of safety well above the minimum recommended value of 1.5. Geophysical monitoring revealed a vertical variation in the electrical resistivity across the dike, which indicates a multilayer structure of the embankment. Without any current in situ data, the geophysical monitoring helped estimating the nature of the materials used and the internal structure of the embankment. These interpretations were validated by geological observation of geotechnical log of the embankment. Based on this study, it is recommended that the water polishing pond be partly filled before waste rock is deposited in TSF #1. In addition, to ensure the stability of the dike, the piezometric head monitoring prior to and during waste rock deposition is recommended.     

Effects of bioleaching on the mechanical and chemical properties of waste rocks

Bioleaching processes cause dramatic changes in the mechanical and chemical properties of waste rocks,and play an important role in metal recovery and dump stability.This study focused on the characteristics of waste rocks subjected to bioleaching.A series of experiments were conducted to investigate the evolution of rock properties during the bioleaching process.Mechanical behaviors of the leached waste rocks,such as failure patterns,normal stress,shear strength,and cohesion were determined through mechanical tests.The results of SEM imaging show considerable differences in the surface morphology of leached rocks located at different parts of the dump.The mineralogical content of the leached rocks reflects the extent of dissolution and precipitation during bioleaching.The dump porosity and rock size change under the effect of dissolution,precipitation,and clay transportation.The particle size of the leached rocks decreased due to the loss of rock integrity and the conversion of dry precipitation into fine particles.     

异质软硬复合地层地铁车站穿越富水断层施工响应与控制

针对异质软硬复合地层地铁车站穿越断层施工变形控制难题,对断层影响下地铁车站开挖过程中围岩力学响应进行研究,探讨不同加固方案下车站围岩变形演化规律,为复杂条件下地铁车站穿越断层施工提供理论指导。以某地铁车站穿越富水断层破碎带为背景,通过室内实验确定特殊地层围岩物理力学性质及破坏特征,结合BQ围岩分级方法确定围岩等级;在此基础上采用有限差分数值模拟软件,对比研究有无地下水影响下地铁车站开挖后围岩应力及沉降变形分布特征,采用控制变量方法研究临时支撑与注浆加固对车站围岩整体稳定性的影响,进而确定合理的施工控制方案。研究结果表明：有无地下水对于异质软硬交叉地层的围岩物理力学特性影响明显,而侵入的辉绿岩尤甚,极易产生沿节理面的剪切滑移破坏;地下水影响下车站拱顶最大沉降值为6.5mm,较之无地下水条件下增大30%;辉绿岩部分（车站右部）最大拉应力为1.62MPa,远大于其极限抗拉强度1.25MPa,故无注浆加固条件下辉绿岩侧可能产生大范围破坏;全断面注浆降低了地下水对围岩变形的影响效果显著,以65°断层为界,断层倾角越小,全断面注浆宽度应越大;基于分析结果,提出全断面注浆+临时支撑+小进尺的过断层车站安全施工方案,监测结果表明应用效果良好。     

Experimental study on remodeling strength of granular materials under different loads and lengths of time

Remodeled clay and sand rock specimens were prepared by designing lateral confinement and water drainage experiments based on the stress exerted on granular materials in a waste dump.An in situ test was conducted in an internal waste dump;the physical and mechanical parameters of the remodeled rock mass dumped at different time and depths were measured.Based on statistics,regression analysis was performed with regard to the shearing stress parameters acquired from the two tests.Other factors,such as remodeling pressure(burial depth),remodeling time(amount of time since waste was dumped),and the corresponding functional relationship,were determined.Analysis indicates that the cohesion of the remodeled clay and its remodeling pressure are correlated by a quadratic function but are not correlated with remodeling time length.In situ experimental results indicate that the shear strength of reshaped granular materials in the internal dump is positively correlated with burial depth but poorly correlated with time length.Cohesion Cand burial depth H follow a quadratic function,specifically for a short time since waste has been dumped.As revealed by both in situ and laboratory experiments,the remodeling strength of granular materials varies in a certain pattern.The consistency of such materials verifies the reliability of the remodeling experimental program.     

Valorization of mining waste and tailings through paste backfilling solution,Imiter operation,Morocco

Mine waste and process tailings storage is one of important challenge for which mining operations are increasingly confronted. Treatment discharges of plants and main part of waste rock development are generally stored on surface areas. The volume and chemical characteristics of these materials generate serious problem for required storage spaces and mainly environmental degradation. Paste backfill(PBF) is one of ingenious solutions to minimize the quantity of tailings to store. PBF is basically defined as a combination of mine processing tailings, binder, and water mixing. The purpose of this paper is to present backfilling components characterization and formula verification for a waste valorization solution through paste backfilling technology in Imiter operation. Obtained results and realized analysis demonstrate PBF conformity and adequacy with assigned underground functions. However the studied recipe can be more ameliorated to obtain an optimal mixture ensuring the required mechanical strength.     

振冲法的现状综述

介绍了振冲法的起源及发展现状,着重论述了填料振冲和无填料振冲技术加固机理的试验研究成果、适用范围和施工设备。振冲法是一种快速加固松软地基的方法,对于表面承载力很低的吹填土地基具有施工设备较轻的特点。无填料振冲相对于填料振冲具有造价更低、施工更快速的优点,但适用范围更小。目前国内已经有较多无填料振冲法加固黏粒含量小于10%的松散粗砂、中砂、细砂、粉砂地基的成功案例。     

东戈壁钼矿露天坑排土场位置与边坡稳定性分析

应用数值模拟技术对新疆东戈壁露天矿边坡不同排土场安全距离问题进行了真实有效地分析,直观地再现了边坡应力和位移变化,并得到边坡的稳定安全系数。结果表明:在没有排土场作用下,露天坑边坡处于相对稳定状态,当排土场安全距离为50m时,安全系数急剧减小到0.68,随着排土场安全距离的增大,安全系数随之增大。当排土场安全距离为300m时,边坡安全系数达到0.99,当安全距离大于400m时,排土场几乎不会对边坡的稳定性造成影响。数值模拟技术对边坡排土场安全距离的确定具有重要的指导意义,为东戈壁露天矿边坡开挖提供了有效的技术支撑。     

交叉隧洞施工通风流场特性研究

施工通风贯穿交叉隧洞施工全过程,是确保施工进度、保障工程安全的关键。针对现有通风方案设计主要依靠经验,缺乏相应的理论支持,常常造成资源浪费等问题,构建交叉隧洞的三维模型,采用基于流体力学理论的数值计算方法模拟交叉隧洞通风流场,通过对隧洞中通风流量占比、风速大小分布的比对,可定量分析交叉角度、施工顺序、串联风机位置等因素对通风流场的影响特性,并提出减小交叉角度、协调施工进度、合理安置串联风机等改善不同情况下通风效果的合理建议。为交叉洞施工通风方案的优化设计提供参考。     

Discrete element approach for mine dump stability analysis

Mine overburden dumps have posed significant safety issues in the operations of various unit operations of open pit min-ing especially the external dumps. The external dumps are composed of a mixture of fragmented rocks and loose soil. Their charac-teristic is comparable to heavily discontinuous solid mass. The conventional approach of limit equilibrium methods provide safety factors for the slope but nothing about the stress-strain characteristics of the large dump mass. The designs of dump location and their respective geometry are integrated for the know-how of the stability characteristics of these dumps. The discrete element method uses a circular disk to represent the granular solid mass and their interactions are described by the Newton's third law of motion. The displacement is described by the sliding of the circular disk. This work is focused on the modeling efficiency of the discrete element methods to represent the behaviour of mine dump masses with the specified joint plane for the limit equilibrium method. The advantage of the work lies on the ease of information retrieval at any point at the dump mass concerning the stress and strain histories, displacement, failures etc. which when integrated produces a better understanding of the stability of the dump masses.     

基于强度折减法随机裂隙岩体结构稳定性分析

克服裂隙岩体确定性分析方法的局限性,采用有限元强度折减法对节理裂隙随机分布的重力坝安全稳定性进行评价。运用Monte-Carlo方法,生成二维和三维随机节理裂隙网络模型,模型较为真实的还原了节理裂隙的分布情况;针对重力坝只含软弱夹层和同时含软弱夹层和节理裂隙两种情况,采用强度折减法对比分析其塑性区和水平位移变化情况。研究结果表明,含节理裂隙的重力坝坝基内部塑性区较多,且局部破坏严重,坝体的水平位移相对较大。该结果可为裂隙岩体地下工程的安全和稳定性研究提供参考。     

Numerical analysis of rainfall effects in external overburden dump

The effect of slope angle for external overburden dump in response to average and heavy rainfall has been analyzed using a two dimensional finite difference method of transient water flow through unsaturated–saturated soil. The external dump stability is evaluated for five geomaterial types on the basis of globally accepted safety factor analysis technique, based on shear strength reduction approach using finite difference method. The results obtained from the finite difference method of analysis indicate that the external dump with more than 30° slope angle is greatly influenced by the rainfall under the studied conditions for geomaterial 3, 4 and 5, whereas dumps with geomaterial 1 and 2 remain safe. The analysis shows that major slope failure is out of preview for the studied rainfall conditions.     

隧道水平旋喷加固效果及不同工法对稳定性影响分析

针对软弱破碎围岩隧道施工极易失稳的问题,采用FLAC2D软件建模对软弱破碎围岩隧道的施工过程进行数值仿真模拟,分析了水平旋喷预加固的效果;探讨了CRD(center cross diagram)法和三台阶法对隧道施工稳定性的影响。研究结果表明:水平旋喷预加固有利于控制沉降和衬砌内力;CRD法最大沉降值、衬砌内力均比三台阶法小,应优先选用;CRD法的中台阶左侧开挖为关键环节,应及时施作衬砌。在此基础上提出了一系列施工优化方案,在厦门公路隧道中实施应用,取得良好的效果,对同类隧道施工具有重要参考意义。     

某卵石砂桩复合地基工程实例

本文所述之工程实例为利用现有的振动打桩设备加以改造,使之能起到振动、水冲、灌注和挤密的作用,在地基中形成卵石夹砂的桩体,与被挤实的淤泥土共同组成复合地基以承受上部的荷载。文章介绍了本工程的设计和施工概况。为了验证本文提出的软基加固方法,在现场进行了载荷试验和沉降观测。本工程主体建筑砌块完工后还进行了技术鉴定,鉴定的结论意见是肯定的。     

深基坑支护对紧邻建筑物变形的分析与监测对比研究

将深基坑、支护结构及周边建筑物作为一个体系,运用数值模拟分析方法对紧邻建筑物的沉降变形随基坑开挖深度的变化进行计算模拟,与实际监测数据进行对比分析,其结论不但证明了支护方案的可行性,同时也对深基坑工程的安全施工提供了一定的指导作用。