采动动载诱导围岩变形破坏的模拟试验研究

发布时间：2019-03-13 18:06

【摘要】：随着我国煤矿开采强度和深度的不断增加,由动载诱发的冲击矿压灾害也逐渐增加。相似模拟试验作为重要实验室研究手段之一,在国内外一些研究单位已开展了冲击动载方面的试验和探索。但从冲击动载对围岩的破坏效应和破坏特点的角度进行研究的较少,且动载大多采用爆破模拟的形式。为此,本文以动静载荷组合加载相似模拟试验为主要研究手段,结合理论分析、数值模拟等方法,对采动动载诱导围岩变形破坏的特征进行了研究。主要结论如下:基于冲击矿压动静载叠加原理及相似理论,分析了围岩动、静载应力条件。依据相似理论,分析了动静载的特点及动载的相似性,分析比较了相似比例系数,在MLT系统中对弗洛德比尺因数中的主要变量量纲进行分析,确定了相似模拟试验的比尺因数并对其量纲进行分析验证。以急倾斜煤层地质条件为基础设计并完成了相似模拟试验,探究采场围岩的应力分布特点及采动动载对其变形破坏的影响,并确定了围岩冲击破坏加速度、位移临界值。结果表明:同一水平分层,煤层底板左侧应力集中程度最高,且随着动载强度的增大,围岩响应特征更加明显,当模拟能量为3.92×10~5J时发生冲击显现。相同动载强度时,随着传播距离的增加,响应特征逐渐减弱,但传播距离差别不大时应力条件成为了响应大小的决定因素。同时,对采动动载诱导巷道围岩变形破坏进行了相似模拟试验研究。结果表明:巷道模型中应力对称分布,顶底板左、右侧静载应力相同,中部应力较低。动载强度增大导致围岩变形破坏更为严重。相同动载时,由于试验设备动载形式限制,巷道“迎载侧”受动载影响最大,加速度、声发射事件更为明显,且模拟能量9.00×10~4J时发生冲击破坏,“背载侧”响应程度略有衰弱,但总体仍处于较高水平,而处于径向位置的巷道拱顶受扰动最小。利用FLAC~(2D)数值模拟软件进行了对照模拟试验分析。结果表明:动载传递过程中在介质中将发生反射和透射,从而引起煤岩应力变化,动载强度越高,诱发围岩变形破坏越严重。相同动载强度时,由于围岩自由空间方向限制,巷道顶底板在垂直方向上响应特征更为明显,而左右两帮在水平方向变形破坏更为严重,且由于反射作用左侧煤壁处变形破坏程度高于内部围岩。巷道“迎载侧”区域受动载影响较大,响应特征较为明显。数值模拟分析与相似模拟试验结果一致,耦合性较好。
[Abstract]:With the increasing intensity and depth of coal mining in China, the impact rock pressure disaster induced by dynamic load also increases gradually. As one of the important laboratory research methods, similar simulation test has been carried out in some domestic and foreign research institutions in the field of impact dynamic load test and exploration. However, there are few studies on the failure effect and characteristics of the surrounding rock by impact dynamic load, and most of the dynamic loads are in the form of blasting simulation. Therefore, in this paper, the characteristics of deformation and failure of surrounding rock induced by mining dynamic load are studied by means of similar simulation test under combined static and static loads, combined with theoretical analysis, numerical simulation and other methods. The main conclusions are as follows: based on the statically static loading superposition principle and similarity theory, the dynamic and static loading stress conditions of surrounding rock are analyzed. According to the similarity theory, the characteristics of dynamic load and the similarity of dynamic load are analyzed and compared. The dimension of main variables in Froude scale factor is analyzed in MLT system. The scale factor of similar simulation test is determined and its dimension is analyzed and verified. Based on the geological conditions of steep inclined coal seam, similar simulation tests are designed and completed. The stress distribution characteristics of surrounding rock of stope and the influence of mining dynamic load on its deformation and failure are discussed, and the acceleration and displacement critical value of surrounding rock shock failure are determined. The results show that the stress concentration on the left side of coal seam floor is the highest with the same horizontal stratification, and with the increase of dynamic load strength, the response characteristics of surrounding rock are more obvious. When the simulated energy is 3.92 脳 10 脳 10 ~ 5 J, the shock appears. At the same dynamic load intensity, the response characteristics gradually weaken with the increase of the propagation distance, but the stress condition becomes the decisive factor of the response size when the propagation distance difference is not small. At the same time, similar simulation tests are carried out to study the deformation and failure of surrounding rock induced by mining dynamic load. The results show that the stress is symmetrically distributed in the tunnel model with the same static stress on the left and right sides of the roof and floor and the lower stress in the middle of the tunnel. The deformation and failure of surrounding rock is more serious due to the increase of dynamic load strength. Under the same dynamic load, due to the limitation of the dynamic load form of the test equipment, the influence of the dynamic load on the "uploading side" of the roadway is the greatest, the acceleration and acoustic emission events are more obvious, and the impact failure occurs when the simulated energy is 9.00 脳 10 脳 10 ~ 4J. The response degree of "back loading side" is a little weak, but it is still at a higher level, while the radial position of tunnel arch is the least disturbed. The FLAC~ (2D) numerical simulation software is used to carry out the comparative simulation test analysis. The results show that the reflection and transmission will occur in the medium during dynamic load transfer, which will cause the change of coal and rock stress. The higher the dynamic load strength, the more serious the deformation and failure of the surrounding rock will be induced. Under the same dynamic load strength, due to the limitation of the free space direction of the surrounding rock, the response characteristics of the roof and floor of the roadway are more obvious in the vertical direction, and the deformation and damage of the left and right sides are more serious in the horizontal direction. The deformation and failure degree of the left coal wall is higher than that of the internal surrounding rock due to reflection. The response characteristics are more obvious in the area of "welcoming side" of roadway under the influence of dynamic load. The numerical simulation analysis is consistent with the similar simulation test results, and the coupling is good.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD324

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