考虑层间剪切特性复合顶板失稳机理及控制
发布时间：2018-08-28 11:56
【摘要】：复合顶板巷道在煤矿中分布广泛,各岩层之间黏结力较弱甚至无黏结力,复合岩层易离层、下沉甚至破坏,导致由下至上的分层冒落,复合顶板的支护是国内外巷道支护的难题之一。复合顶板层理面是岩体中的薄弱部分,是影响岩体稳定的重要因素之一。层理面抗剪强度参数的确定是复合顶板、岩质边坡稳定等问题分析关键问题。因此,研究复合顶板层间剪切特性及考虑层间剪切特性的复合顶板控制有重要意义。论文综合利用实验室实验、理论分析、数值计算等相结合的研究方法,考虑层间剪切特性对复合顶板稳定性及其控制机理进行研究。首先,对节理面的粗糙度JRC进行了测定,并将节理面轮廓导入PFC,在不同法向正应力作用下进行剪切实验,利用最小二乘法线性回归求出节理面的内摩擦角。对复合顶板的稳定性进行了力学分析,根据组合梁分析得出通过增加层间剪切强度,可提高复合顶板的抗变形及破坏能力,在层状复合顶板中引入了复合顶板关键层进行力学分析,并在考虑层间剪应力的基础上对推导出复合顶板关键层破断距,提出复合顶板柔性控制层的概念并对其判定及对顶板控制的作用进行了分析,最后利用C#语言在Visual Studio 2005平台进行了复合顶板柔性控制层判别软件实现。利用UDEC数值计算软件,对复合顶板中层理面参数(内摩擦角、内聚力、抗拉强度等)对复合顶板的稳定性影响进行了研究:随层理面内摩擦角和内聚力的增大,巷道变形、裂隙发育、破坏范围逐渐变小;随内摩擦角和内聚力的增大,巷道变形对两参数敏感性降低,改变顶板层理面抗拉强度对帮部和底板破坏范围影响不明显;巷道顶板围岩的破坏形式主要以剪切破坏和拉破坏为主,且两种破坏多同时出现,巷道帮部的破坏形式仍主要为剪切破坏和拉破坏,帮部围岩的破坏形态呈现倒三角形分布,底板破坏以拉破坏为主。顶板裂隙的发育总体规律为:顶板裂隙发育可分为快速增长阶段和平稳阶段,煤壁裂隙的生成过程中,存在明显的裂隙产生-裂隙闭合-裂隙持续增长的三个阶段。以老石旦煤矿为背景,对复合顶板支护机理和支护对策进行了研究分析。利用UDEC数值计算软件研究了锚杆的抗剪切作用效果,锚杆的整体作用效果和锚索加强支护效果。将围岩破坏演化规律总结为四个阶段,第一阶段为起始阶段,第二阶段破坏往顶板深部发育,第三阶段帮部在顶板挤压作用下发生大量剪切和拉伸破坏,最后一阶段顶底板破坏发育进入稳定阶段。通过统计不同形式破坏的接触长度(contact length)和总接触长度的比值比较巷道围岩不同区域的破坏形式。提出针对不同区域顶板的破坏形式不同,应进行不同区域分区支护的策略。
[Abstract]:The composite roof roadway is widely distributed in the coal mine, and the bonding force between each rock layer is weak or even no bonding force. The composite rock strata are easy to separate, sink or even destroy, resulting in the falling of the layers from the bottom to the top. The support of composite roof is one of the difficult problems in roadway support at home and abroad. Composite roof bedding plane is a weak part of rock mass and one of the important factors affecting rock mass stability. The determination of shear strength parameters of bedding plane is a key problem in the analysis of composite roof and rock slope stability. Therefore, it is of great significance to study the interlaminar shear characteristics of composite roof and the control of composite roof considering interlaminar shear characteristics. In this paper, the stability and control mechanism of composite roof are studied by means of laboratory experiment, theoretical analysis and numerical calculation. Firstly, the roughness of joint surface JRC is measured, and the joint surface profile is introduced into the shear experiment of PFC, under different normal stresses, and the internal friction angle of joint surface is obtained by least square linear regression. The stability of composite roof is analyzed by mechanics. According to the analysis of composite beam, it is concluded that the deformation resistance and failure resistance of composite roof can be improved by increasing the interlaminar shear strength. The key layer of composite roof is introduced into the layered composite roof for mechanical analysis, and the breaking distance of the key layer of composite roof is deduced on the basis of considering the interlaminar shear stress. This paper puts forward the concept of flexible control layer of composite roof and analyzes its judgment and function to roof control. Finally, the discriminant software of flexible control layer of composite roof is implemented by using C # language in Visual Studio 2005 platform. By using UDEC software, the influence of the parameters of the middle layer of composite roof (internal friction angle, cohesive force, tensile strength, etc.) on the stability of composite roof is studied: with the increase of the friction angle and cohesion of the bedding plane, the roadway deformation is studied. With the increase of internal friction angle and cohesion, the sensitivity of roadway deformation to two parameters is decreased, and the influence of changing tensile strength of roof bedding surface on the failure range of roof and floor is not obvious. The main failure forms of roadway roof surrounding rock are shear failure and tensile failure, and the two kinds of destruction occur at the same time. The failure form of roadway wall rock is still shear failure and tensile failure, and the failure form of wall rock of roadway is inverted triangle distribution. The main failure of the bottom plate is tensile failure. The general law of roof crack development is as follows: roof crack development can be divided into rapid growth stage and stable stage. In the process of coal wall crack formation, there are three stages of obvious crack generation, crack closure and continuous growth. Taking Laoshidan coal mine as the background, the mechanism of composite roof support and supporting countermeasures are studied and analyzed. The anti-shear effect of bolt, the whole effect of bolt and the effect of strengthening support of anchor cable are studied by using UDEC numerical calculation software. The evolution law of surrounding rock failure is summarized into four stages, the first stage is the initial stage, the second stage is the deep development of the roof, and the third stage is the large amount of shear and tensile failure of the wall under the action of roof extrusion. In the last stage, the top and bottom plate damage and development entered a stable stage. By calculating the ratio of contact length (contact length) and total contact length (contact length) of different failure forms, the failure patterns of different surrounding rock of roadway are compared. In view of the different failure form of roof in different area, the strategy of different area partition support should be carried out.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD353
本文编号：2209324
[Abstract]:The composite roof roadway is widely distributed in the coal mine, and the bonding force between each rock layer is weak or even no bonding force. The composite rock strata are easy to separate, sink or even destroy, resulting in the falling of the layers from the bottom to the top. The support of composite roof is one of the difficult problems in roadway support at home and abroad. Composite roof bedding plane is a weak part of rock mass and one of the important factors affecting rock mass stability. The determination of shear strength parameters of bedding plane is a key problem in the analysis of composite roof and rock slope stability. Therefore, it is of great significance to study the interlaminar shear characteristics of composite roof and the control of composite roof considering interlaminar shear characteristics. In this paper, the stability and control mechanism of composite roof are studied by means of laboratory experiment, theoretical analysis and numerical calculation. Firstly, the roughness of joint surface JRC is measured, and the joint surface profile is introduced into the shear experiment of PFC, under different normal stresses, and the internal friction angle of joint surface is obtained by least square linear regression. The stability of composite roof is analyzed by mechanics. According to the analysis of composite beam, it is concluded that the deformation resistance and failure resistance of composite roof can be improved by increasing the interlaminar shear strength. The key layer of composite roof is introduced into the layered composite roof for mechanical analysis, and the breaking distance of the key layer of composite roof is deduced on the basis of considering the interlaminar shear stress. This paper puts forward the concept of flexible control layer of composite roof and analyzes its judgment and function to roof control. Finally, the discriminant software of flexible control layer of composite roof is implemented by using C # language in Visual Studio 2005 platform. By using UDEC software, the influence of the parameters of the middle layer of composite roof (internal friction angle, cohesive force, tensile strength, etc.) on the stability of composite roof is studied: with the increase of the friction angle and cohesion of the bedding plane, the roadway deformation is studied. With the increase of internal friction angle and cohesion, the sensitivity of roadway deformation to two parameters is decreased, and the influence of changing tensile strength of roof bedding surface on the failure range of roof and floor is not obvious. The main failure forms of roadway roof surrounding rock are shear failure and tensile failure, and the two kinds of destruction occur at the same time. The failure form of roadway wall rock is still shear failure and tensile failure, and the failure form of wall rock of roadway is inverted triangle distribution. The main failure of the bottom plate is tensile failure. The general law of roof crack development is as follows: roof crack development can be divided into rapid growth stage and stable stage. In the process of coal wall crack formation, there are three stages of obvious crack generation, crack closure and continuous growth. Taking Laoshidan coal mine as the background, the mechanism of composite roof support and supporting countermeasures are studied and analyzed. The anti-shear effect of bolt, the whole effect of bolt and the effect of strengthening support of anchor cable are studied by using UDEC numerical calculation software. The evolution law of surrounding rock failure is summarized into four stages, the first stage is the initial stage, the second stage is the deep development of the roof, and the third stage is the large amount of shear and tensile failure of the wall under the action of roof extrusion. In the last stage, the top and bottom plate damage and development entered a stable stage. By calculating the ratio of contact length (contact length) and total contact length (contact length) of different failure forms, the failure patterns of different surrounding rock of roadway are compared. In view of the different failure form of roof in different area, the strategy of different area partition support should be carried out.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD353
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