模拟地下工程应力环境梯度加载下的岩爆机理研究

发布时间：2018-06-16 05:38

本文选题：高地应力 + 侧压力系数　；参考：《武汉理工大学》2013年博士论文

【摘要】：随着矿业工程、水电工程和隧道工程逐步向深部岩体发展,深部硬脆岩体开挖扰动造成局部应力集中,围岩所受应力梯度增大,伴随而来的岩爆灾害也逐步增加。而对于不同应力环境和应力路径下岩体开挖扰动产生应力梯度对岩爆灾害的研究非常少,且目前岩爆试验还大多处于小尺寸试件的均布加卸载阶段,为研究梯度加载对岩体受力直至发生岩爆的影响,本文通过对在地下工程不同应力环境与应力路径下岩体的受力变化进行分析,总结深部岩体开挖引起围岩应力场分布的主要形式,采用典型的应力梯度加卸载路径,结合自主研发的岩爆加载装置对试件进行室内试验研究,以分析不同应力梯度对试件产生岩爆的影响,并通过数值模拟与室内试验验证的方法,系统研究了不同应力梯度和应力环境下的岩爆机理。论文主要取得以下研究成果： (1)通过对隧道开挖影响区岩体进行应力弹性理论解析解分析,并利用FLAC3D有限差分软件对不同开挖深度、不同侧压力系数下的马蹄形隧道进行开挖模拟,得到不同开挖深度和侧压力系数下,隧道开挖引起岩体应力梯度分布趋势,总结隧道开挖掌子面逐渐接近岩体监测面并随开挖进一步推进的过程中,测试面岩体受开挖影响的应力梯度变化规律,推导出对隧道围岩所受应力梯度值随开挖步骤的拟合公式。 (2)选择满足岩爆倾向性的相似模型材料,并通过室内试验得到模型试件的基本物理力学指标。利用自主研发的YB-A型岩爆加载装置对大尺寸试件进行顶部梯度加载的四组不同加卸载路径的岩爆试验,通过改变不同侧压力系数、单面卸载时顶部不同加载力大小,对顶部进行不同速率加载的方式,对试件在四种加载路径下发生岩爆时,其卸载面的岩爆破坏形态进行分析,并得出试件产生岩爆时,其顶部所受应力梯度大小与试件经历加卸载环境和加载路径的关系。 (3)为分析试件在四种加卸载路径下发生岩爆与试件顶部所受应力梯度分布的影响,通过采集试件在各加载路径中的应变片变形数据,对比试件在加卸载前后的CT成像分析,并对岩爆试验后的岩爆碎屑进行分形分析,得出试件发生岩爆的过程是试件卸载面附近岩体经历了：试件在受加载时能量吸收-卸载面压密-试件卸载后在其卸载面中部拉裂破坏-破裂成板的岩爆破坏过程。CT成像图直观地反应出试件卸载面附近的加载压密区和卸载后试件内部的损伤区；最后通过对岩爆碎屑的分形维数值计算,建立了岩爆烈度与试件加载路径的关系。进一步分析了试件在四种加卸载路径下的岩爆特性。 (4)基于能量耗散原理,利用3DEC离散元软件并嵌入弹性能密度的fish语言,计算并追踪测点的弹性能密度变化的全过程,选择与室内试验相类似的加载应力梯度对模型试件进行加卸载模拟,以对室内试验结果进行验证与补充。模拟结果再现试件在高应力梯度条件下卸载时,随着试件顶部应力梯度的逐渐增加,试件卸载面呈局部剥落,乃至出现块体喷射的岩爆过程,数值模拟试验与相同路径下的室内试验结果较吻合。
[Abstract]:With the mining engineering, the hydropower project and the tunnel project are gradually developing to the deep rock mass. The local stress concentration is caused by the excavation of the deep hard brittle rock mass, the stress gradient of the surrounding rock increases and the rock burst disaster increases gradually. The stress gradient is produced for rock burst disaster under different stress environment and stress path. In order to study the influence of gradient loading on rock mass to rock burst, this paper analyzes the stress changes of rock mass under the different stress environment and stress path under the underground engineering, and summarizes the surrounding rock should be caused by the deep rock excavation. The main form of the force field distribution is a typical stress gradient loading and unloading path, combined with the self developed rock burst loading device to carry out laboratory tests to analyze the effects of different stress gradient on the rock burst produced by the specimen, and the different stress gradient and stress ring are systematically studied through numerical simulation and laboratory test verification. The main achievements of the paper are as follows:
(1) through the analytical solution analysis of the stress elastic theory of the rock mass in the tunnel excavation, and using the FLAC3D finite difference software to simulate the excavation of the horseshoe tunnel under different excavation depth and different side pressure coefficient, the stress gradient distribution trend of rock mass caused by tunnel excavation under different excavation depth and side pressure coefficient is obtained, and the tunnel is summed up. In the course of the tunnel face gradually approaching the monitoring surface of rock mass and with the process of excavation further, the stress gradient change law of the rock mass affected by the excavation is tested, and the fitting formula of the stress gradient value of the tunnel surrounding rock is derived with the excavation step.
(2) select the similar model materials that meet the tendency of rock burst, and get the basic physical and mechanical indexes of the model specimens through indoor test. By using the independent YB-A type rock burst loading device, four groups of different loading and unloading paths on the top of the large size specimen are tested on the top gradient loading path. By changing the different side pressure coefficient, the single side unloading is changed. At the top of the different loading force, the top is loaded with different speed, and the rock burst failure pattern of the unloading surface is analyzed when rock burst occurs under four loading paths, and the relationship between the stress gradient on the top of the specimen and the loading and unloading environment and loading path is obtained when the specimen is produced by rock burst.
(3) in order to analyze the influence of the rock burst and the stress gradient distribution on the top of the specimen under four loading and unloading paths, the CT imaging analysis of the specimen before and after loading and unloading is compared by collecting the strain data of the strain sheet in each loading path, and the fractal analysis of the rock burst after the rock burst test is carried out, and the rock burst of the specimen is obtained. The process is that the rock mass near the unloading surface of the specimen is experienced: the.CT image of the rock burst failure process at the unloading surface after the loading is loaded by the loading - unloading surface pressure - the rock burst failure process in the middle of the unloading surface after the loading is unloaded. By calculating the fractal dimension of rock burst, the relationship between the rock burst intensity and the loading path of the specimen is established, and the rock burst characteristics of the specimen under the four loading and unloading paths are further analyzed.
(4) based on the principle of energy dissipation, using the 3DEC discrete element software and embedding the fish language of elastic energy density, the whole process of elastic energy density change is calculated and tracked, and the loading stress gradient similar to the laboratory test is used to simulate the loading and unloading of the model test parts, so as to verify and supplement the laboratory test results. With the increasing stress gradient at the top of the specimen under the high stress gradient, the unloading face of the specimen is partial peeling and even the rock burst in the block ejection. The numerical simulation test is in good agreement with the laboratory test results under the same path.
【学位授予单位】：武汉理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU45

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