采煤沉陷区岩质边坡悬臂-断裂失稳破坏模式研究.pdf

采煤沉陷区岩质边坡悬臂-断裂 失稳破坏模式研究 重庆大学硕士学位论文 学术学位 学生姓名崔剑锋 指导教师谢 强 副教授 徐 洪 博 士 专 业土木工程 学科门类工 学 重庆大学土木工程学院 二 O 一四年五月 Study on Cantilever-fracture Instability Failure Mode of Rock Slope in Coal Mining Subsided Area A Thesis ted to Chongqing University in Partial Fulfillment of the Requirement for the Master’s Degree of Engineering By Cui Jianfeng Supervised by Ass. Prof. Xie Qiang Assistant Supervised by Dr. Xu Hong Specialty Civil Engineering School of Civil Engineering, Chongqing University, Chongqing, China May, 2014 中文摘要 I 摘 要 重庆市煤炭资源开发历史悠久，但随着煤炭资源的开采，造成了大量的采煤 沉陷区并伴随着大量的滑坡、崩塌等地质灾害。目前，矿区由于地下开采，地表 坡体的应力平衡状态短时间内被破坏，容易引起突发性的滑坡或崩塌。而目前关 于采矿活动与滑坡灾害的研究往往以单个滑坡为研究对象，缺乏对其系统规律的 认识，因而对沉陷区地质灾害防治指导价值有限。 本文以科研项目采煤沉陷区基岩陡坡孕灾机制及成灾模式研究为依托，通过 对重庆周边采煤矿区岩质边坡资料的统计调查，首先将煤矿沉陷区的岩质边坡的 破坏模式划分为较为典型的四大类，建立起一整套的分类体系，其中悬臂-断裂失 稳破坏模式做为重点研究； 其次， 通过对该地区某一典型悬臂-断裂模式的边坡 望霞危岩进行建模分析，基于对其破坏过程的模拟，分析总结出悬臂-断裂失稳破 坏模式的破坏过程及机理；再次，将悬臂-断裂破坏模式的坡体模型进行简化，通 过对完整坡体以及缺陷坡体的区分，分别建立数值模型进行模型在开挖作用下的 受力特征分析；最后，在已建立模型的基础上，确定各类影响因素对该类型岩质 边坡稳定性的影响规律。 主要结论如下 ① 通过现场调查和分析，将重庆市采煤沉陷区采矿活动下坡体变形破坏的力 学模式分为悬臂-断裂破坏模式、外倾-拉裂破坏模式、内倾-压致破坏模式和外推- 压致破坏模式；根据采矿活动对坡体稳定性的影响程度不同，将沉陷区基岩陡坡 破坏划分为采矿主导型和采矿诱导型两类；同时根据现场调查结果，提出本地区 采煤沉陷区基岩陡坡的变形破坏形式主要有3类，即滑移形式、剪切形式和倾倒 形式。 ② 采用数值分析，针对望霞危岩这一具体坡体的变形失稳过程进行研究，揭 示了采矿条件下岩质坡体的变形失稳过程及机理采矿活动对坡体整体性的破坏 主要表现在两个方面，一方面使原有的裂隙、缺陷进一步发展，或形成新的裂隙， 另一方面采空区会产生新的裂隙， 并逐渐向上部发展， 当与坡体上部裂隙贯通时， 坡体则发生失稳破坏；另外，研究得出采空区上部岩体的剪切应力随采空区范围 的扩大而增加的规律， 并总结得出悬臂-断裂模式下坡体破坏演化过程的四个阶段。 ③ 重点以悬臂-断裂型破坏模式为基础， 在提出完整坡体以及缺陷坡体的概念 之后，分别对两种不同类型的坡体的破坏失稳进行研究，研究发现完整坡体条件 下，下部开挖对坡体稳定性造成的影响规律与岩体的岩性有关，在岩性较为坚硬 时，随着悬臂高度的增加，最大断裂长度有现增加后趋向平缓的趋势，而在岩性 重庆大学硕士学位论文 II 较软时，随着悬臂高度的增加，最大断裂长度呈现下降趋势；缺陷坡体条件下， 不同裂缝深度条件、采空区距离变化时，煤层开挖前后裂缝尖端应力集中系数均 发生变化，并呈现一定的规律性。 ④ 在坡体稳定性的影响因素研究中，提出了安全系数变化率的概念，用于分 析采矿活动中对坡体稳定性存在影响的各项因素，确定了煤层倾角、上覆坡体岩 性、上覆坡体倾角、采空区宽度以及采空区位置对采空区岩质坡体稳定性的影响 规律。 本文在研究过程中采用了一些新的研究思路及方法，同时在前人研究成果的 基础上分析总结出了一些结论，对于促进重庆市地质灾害防治工作的研究及实践 均能起到积极的作用。 关键词采煤沉陷区，岩质坡体，破坏模式，影响因素 英文摘要 III ABSTRACT Chongqing has a long history of coal resource development. However, the exploitation of coal resources results in a large number of coal mining subsidence and accompanied by a large number of landslides, avalanches and other geological disasters, which have a serious impact on mine geological environment and social environment. In previous studies, more thorough understanding of soil landslide has been got which also has strong guidance in production. Despite the steep bedrock has been also launched over the corresponding research and some achievements has made, but for their failure modes and understanding the failure mechanism is still not perfect. The current research on mining activities and landslide disasters often focus on one single landslide for the study, but lack of the awareness of their systems regularly, and thus its guidance for subsidence prevention of geological disasters will be of limited value. According to the research report Study on Steep Bedrock Mechanism and Disaster Mode in Mining Subsidence which author participated in, through the survey which the data around Chongqing coal mine rock slope, some work is done within this article. Firstly, the failure mode of mine subsidence of rock slope into typical four categories are proposed, and also a set of classification system is proposed beyond that. The cantilever-fracture failure mode among them is picked out as the focus of this study. Secondly, a typical example of the cantilever-fracture failure mode of subsidence slope which is called the Wangxia perilous rock is chosen to be analyzed. Research of this example is done based on its failure process, which analyzes and summarizes the cantilever-fracture failure mode. Then, the cantilever-fracture failure mode was simplified to a numerical model and by dividing this numerical model of slopes to complete and defect one, mechanical characteristics of the slope under excavation is studied. Finally, on the basis of the model by changing the conditions of the model parameters, the impact of this type of rock slope stability and the regular pattern caused by the impact factors are determined. Following conclusions and achievements have been made ① Through field investigation and the results of analysis, main mechanical modes of Chongqing coal mining subsidence damage deation downhill are proposed 重庆大学硕士学位论文 IV which including cantilever-fracture failure mode, extraversion-crack failure mode, introversion-pressure-induced failure mode and extrapolation-pressure-induced failure mode. According to the different impact of mining activities on the slope stability, the steep bedrock subsidence damage is divided into mining and mining-induced type. According to the results of the field survey, three main categories of deation and damage of steep bedrock in local coal mining subsidence are proposed slip , cut and dumping . ② By using numerical analysis, the deation process of a particular slope instability is studied, which revealing the instability process and mechanism of deation under mining conditions of rocky slope the damage caused by mining activities to the integrity of the slope is mainly manifested in two aspects, one is promoting the original crack development, the other one is producing new cracks. And also, according to the study, one regular pattern has been found that gob shear stress increases with the expand of the mined area in upper rock mining. Four stages of the evolution of slope damage under cantilever - fracture mode is found. ③ Focused and based on cantilever - fracture failure mode, the concept of complete slope and defect slope is proposed. And instability criterion under two conditions is also studied. Then law figure of the failure law is drawn after the statistics of data results. Under the complete slope conditions, to relatively hard rock, with increasing height cantilever, the maximum length of the break trend is first ascension then flatten, and when the rock is relatively soft, with increasing height cantilever, the maximum breaking length trend downward; under defect slope conditions, in different crack depths and gob distance, the concentrated crack tip stress factors around the coal excavation vary regularly. ④ The concept change rate of the safety factor is proposed which can be used to analyze the factors affecting mining activity in the presence of slope stability. By studying the influence of various factors which influence the stability of rock slope, influence regular pattern of factors including dip of coal bed, overlying slope lithology, overlying slope inclination, mined-out area width and mined-out area position is determined. In this paper, some new ideas and s for research are proposed in the course of the study, and some conclusions are summed up on the basis of previous research 英文摘要 V results, which can play a positive effect for the promotion of research and practice of prevention and control of geological disasters in Chongqing. Keywords Mining subsidence, Rocky slope, Failure mode, Influence factors 重庆大学硕士学位论文 VI 目 录 VII 目 录 中文中文摘要摘要 .......................................................................................................................................... I 英文摘要英文摘要 ....................................................................................................................................... III 1 绪绪 论论 ......................................................................................................................................... 1 1.1 选题背景及研究意义选题背景及研究意义 ................................................................................................................... 1 1.1.1 选题的背景 ..................................................................................................................... 1 1.1.2 研究的意义 ..................................................................................................................... 2 1.2 国内外研究现状国内外研究现状 ............................................................................................................................ 2 1.2.1 岩质边坡失稳研究现状 ................................................................................................. 2 1.2.2 采煤沉陷区边坡稳定性研究现状 .................................................................................. 4 1.3 研究内容和技术路线研究内容和技术路线 ................................................................................................................... 5 1.3.1 研究的主要内容 ............................................................................................................. 5 1.3.2 研究技术路线图 ............................................................................................................. 6 2 采煤沉陷区基岩陡坡变形破坏模式分类研究采煤沉陷区基岩陡坡变形破坏模式分类研究 ................................................... 9 2.1 采煤沉陷区岩质坡体破坏模式采煤沉陷区岩质坡体破坏模式 .................................................................................................. 9 2.1.1 重庆市采煤沉陷区岩质坡体变形失稳现状调查 .......................................................... 9 2.1.2 采矿活动对斜坡变形失稳影响模式 .............................................................................. 9 2.2 沉陷区基沉陷区基岩陡坡成灾模式分类岩陡坡成灾模式分类 ................................................................................................ 14 2.2.1 分类原则及依据 ........................................................................................................... 14 2.2.2 沉陷区基岩陡坡变形破坏模式分类体系 .................................................................... 15 2.2.3 沉陷区岩质坡体变形破坏模式的识别 ........................................................................ 17 2.3 小结小结 .............................................................................................................................................. 17 3 采煤沉陷区岩质坡体悬臂采煤沉陷区岩质坡体悬臂-断裂失稳过程断裂失稳过程及机理研究及机理研究以望霞危以望霞危 岩为例岩为例 ............................................................................................................................................ 19 3.1 工程概况及岩土参数工程概况及岩土参数 ................................................................................................................. 19 3.1.1 望霞危岩基本情况 ....................................................................................................... 19 3.1.2 望霞危岩卸荷裂隙及塌陷坑发育特征 ........................................................................ 20 3.1.3 危岩的形成及演化分析 ............................................................................................... 21 3.2 分析模型范围及岩分析模型范围及岩土参数土参数 ......................................................................................................... 22 3.2.1 望霞危岩煤矿开采情况及分析范围选择 .................................................................... 22 3.2.2 岩土体力学参数 ........................................................................................................... 24 3.3 模型分析及分析过程模型分析及分析过程 ................................................................................................................. 25 重庆大学硕士学位论文 VIII 3.3.1 三维数值分析模型 ....................................................................................................... 25 3.3.2 开挖过程及监测点 ....................................................................................................... 26 3.4 采煤对坡体稳定性的影响过程分析采煤对坡体稳定性的影响过程分析 ........................................................................................ 27 3.4.1 采矿条件下岩质坡体内部应力分析 ........................................................................... 27 3.4.2 煤层开挖对坡体的位移分析 ....................................................................................... 29 3.5 有限元分析结果与现场实际的对比分析有限元分析结果与现场实际的对比分析 ................................................................................ 37 3.6 采煤坡体稳定性变化及机理分析采煤坡体稳定性变化及机理分析 ............................................................................................. 38 3.6.1 采矿条件下坡体稳定性变化过程 ............................................................................... 38 3.6.2 采矿条件下岩质坡体变形失稳机理 ........................................................................... 39 3.7 小结小结 ............................................................................................................................................... 40 4 完整坡体与缺陷坡体概念下的悬臂完整坡体与缺陷坡体概念下的悬臂-断裂破坏模式分析断裂破坏模式分析 .......................... 43 4.1 采矿上覆岩体悬臂梁简化模型的提出采矿上覆岩体悬臂梁简化模型的提出 .................................................................................... 43 4.1.1 采矿上覆岩体悬臂梁与理想模型的等效性分析 ....................................................... 43 4.1.2 悬臂梁简化模型的提出 ............................................................................................... 44 4.2 完整坡体悬臂完整坡体悬臂-断裂失稳破坏模式数值模型断裂失稳破坏模式数值模型 .......................................................................... 46 4.2.1 简化数值模型的提出 ................................................................................................... 46 4.2.2 完整坡体失稳破坏的条件确定 ................................................................................... 47 4.2.3 完整坡体失稳破坏的过程分析 ................................................................................... 47 4.3 缺陷坡体条件下悬臂缺陷坡体条件下悬臂-断裂失稳破坏模式研究断裂失稳破坏模式研究 ...................................................................... 58 4.3.1 缺陷坡体的定义 ........................................................................................................... 58 4.3.2 缺陷坡体失稳条件的确定 ........................................................................................... 58 4.3.3 缺陷坡体缺陷处的应力集中 ....................................................................................... 59 4.3.4 缺陷坡体采矿失稳简单判据 ....................................................................................... 64 4.4 小结小结 ............................................................................................................................................... 64 5 采煤沉陷区岩质坡体悬臂采煤沉陷区岩质坡体悬臂-断裂失稳破坏断裂失稳破坏模式下的影响因素模式下的影响因素 ............... 67 5.1 采煤沉陷区岩质坡体失稳影响因素分类采煤沉陷区岩质坡体失稳影响因素分类 ................................................................................ 67 5.1.1 坡体自身因素 ............................................................................................................... 67 5.1.2 采煤活动因素 ............................................................................................................... 69 5.2 采煤沉陷区坡体稳定性的影响因素分析采煤沉陷区坡体稳定性的影响因素分析 ................................................................................ 70 5.2.1 采煤活动主要影响因子的选择及依据 ....................................................................... 70 5.2.2 分析指标及分析方法 ................................................................................................... 71 5.2.3 分析模型及参数的选取 ............................................................................................... 71 5.2.4 各影响因子影响过程分析 .......................................................................................