冲击地压预测的煤岩变形局部化方法
Study on localization method of coal rock deformation for rock burst prediction
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摘要: 冲击地压预测是冲击地压防治的前提和基础,是冲击地压研究中的一个重要内容,针对目 前冲击地压前兆和冲击地压孕育过程之间内在的本质联系不清问题,从煤岩变形破坏的固有特征 及冲击地压的失稳问题本质出发,借鉴经典力学中的能量原理,提出了以煤岩变形局部化为前兆的 冲击地压预测方法。 根据虚位移原理和稳定性理论,推导并得到了冲击地压发生临界条件和煤岩 变形局部化发生条件,分析煤岩变形局部化与冲击地压内在联系。 采用梯度塑性理论,通过引入内 部长度参数,构建煤岩变形局部化模型,分析了变形局部化带宽带的影响因素。 给出了测量内部长 度参数的实验方法,对变形破坏向某一区域集中,且集中区具有一定尺度的现象进行理论解析。 根 据变形局部化的时空演化特点,引入描述变形局部化的空间聚集性、梯度显著性和曲率显著性指 标,从 “时间演化”属性和“结构演化”属性对变形局部化状态进行识别。 对变形局部化预测方法 进行初步的应用研究,分别采用实验的声发射数据和现场的微震数据,预测煤岩试件破坏区域和煤 矿冲击地压危险区域。 研究表明:煤岩变形局部化开始条件和冲击地压发生的临界条件相同,即冲 击地压孕育演化过程和煤岩变形局部化的过程具有一致性;煤岩变形局部化带宽度与材料内部长 度参数和煤岩冲击能指数有关,随着材料内部长度增大,变形局部化带宽度线性增大,随着煤岩冲 击能指数增大,变形局部化带宽度非线性减小;根据实验和现场初步应用结果,表明空间聚集性、梯 度显著性和曲率显著性指标能够描述和追踪变形局部化时空演化特征,变形局部化预测冲击地压 危险区域方法具有可行性。Abstract: Rockburst prediction is the premise and foundation of rockburst prevention and control,and is an impor⁃ tant topic in rockburst research. Aiming at the problem that the intrinsic relationship between the precursor and the gestation process of rockburst is unclear,a prediction method of rockburst with the localization of coal and rock deformation as the precursor is put forward. Based on the energy principle of classical mechanics,the method starts from the inherent characteristics of coal and rock deformation and failure and the essence of rockburst instability.According to the principle of virtual displacement and stability theory,the critical conditions of rockburst and the con⁃ ditions of coal and rock deformation failure localization are deduced and obtained,and the internal relationship be⁃ tween coal and rock deformation failure localization and rockburst is analyzed. Based on the gradient plasticity theory,the deformation failure localization model of coal and rock is established by introducing the internal length pa⁃ rameter,and the influence factors of deformation failure localization band are analyzed. Also,the experimental method of measuring the internal length parameter is given,and the phenomenon that the deformation and failure concentrate in a certain area and the concentrated area has a certain scale is theoretically analyzed. According to the temporal and spatial evolution characteristics of deformation failure localization,the spatial aggregation,gradient saliency and curva⁃ ture saliency indexes are introduced,and the deformation failure localization state is identified from the attributes of “time evolution” and “structure evolution”. The preliminary application of deformation failure localization predic⁃ tion method is studied,and the experimental acoustic emission data and field microseismic data are respectively used to predict the damaged area of coal and rock specimen and the dangerous area of coal mine rockburst. The study shows that the starting condition of coal and rock deformation failure localization is the same as the critical condition of rockburst,that is,the gestation and evolution process of rockburst is consistent with that of coal and rock deformation failure localization. The width of deformation failure localization zone is related to the internal length parameters of the material and the impact energy index of the coal. With the increase of the internal length of the material,the width of deformation localization zone increases linearly, and with the increase of the impact energy index of the coal,the width of deformation failure localization zone decreases nonlinearly. According to the experimental and field preliminary application results,it shows that the spatial aggregation,gradient saliency and curvature saliency inde⁃ xes can describe and track the temporal and spatial evolution characteristics of deformation failure localization, and the method of deformation failure localization to predict the dangerous area of rockburst is feasible.