厚松散层下采动覆岩运移规律及地表沉陷时空预测研究

发布时间：2018-05-06 13:33

本文选题：移动与变形 + 正态分布时间函数　；参考：《中国矿业大学(北京)》2017年博士论文

【摘要】：矿山开采尤其是煤炭开采所产生的问题由来已久,在不同地质采矿条件下的矿体开采所诱发的一系列开采沉陷问题复杂多变,而厚松散层下煤炭大规模开采产生的开采沉陷现象比较突出,进而导致开采后所产生的地表沉陷范围、沉陷量和沉陷位置的时空预测难度加大,同时对覆岩裂隙场、位移场和应力场的发育特征和规律产生显著影响。由于开采沉陷严重影响了煤矿安全生产,造成环境破坏及影响了煤炭资源的采出。因此,对厚松散层下煤层开采地表移动变形规律、覆岩运移规律以及沿空留巷充填体和围岩协同作用关系开展研究,将有助于提高煤炭资源产量,延长矿井服务年限,预防或降低矿井地质灾害,促进煤炭工业安全、科学和可持续发展以及煤矿区的良性生态循环。实际上,开采沉陷现象是覆岩移动传播到地表的具体表现形式,覆岩移动是地表沉陷产生的动力和诱因。因此,对地表移动变形规律研究首先要从源头和机理上对采动覆岩运移、裂隙发育规律、应力-应变特征等开展深入研究和探索。本次研究矿区以云驾岭煤矿三采区工程地质条件为研究背景,其典型的地质采矿条件是松散层厚度较大、采高大,第四系松散层平均厚度一般为90-150m,平均120m,开采2#煤层,煤层平均厚度4.2m,煤层倾角17°。论文采用了现场监测、理论分析、实验室测试和数值模拟相结合的综合研究方法,系统地开展了地下采场围岩应力及应变规律、上覆岩层变形及裂隙场发育、煤层开采引起的地表移动变形及沉陷等方面的研究,实现了由井下采场—覆岩—地表的立体协同研究。论文主要开展了以下工作:在厚松散层下地表沉陷规律方面,布设了地表移动观测站,对云驾岭煤矿三采区12303工作面和12305工作面开采引起的地表沉陷开展了系统的监测,整个监测过程中共实施水准测量11次,全面观测5次,并分析了周边工作面对观测站可能产生的影响。基于现场实测数据,分析了两个工作面开采后Z线和U线下沉、倾斜、曲率、水平移动和水平变形终态沉陷特征,确定了地表终态移动变形角值参数;分析了两工作面开采后U线和Z线地表动态移动变形特征,确定了工作面推进度与地表最大下沉点的位置关系;研究了12303工作面和12305工作面开采后地表下沉速度的变化规律,求取了最大下沉速度滞后距、最大下沉速度滞后角、超前影响距和超前影响角;通过回归分析确定了地表最大下沉速度的经验公式。从沉陷盆地边界角、最大下沉角、下沉系数等方面对比分析了云驾岭矿与徐淮矿区、开滦矿区等厚松散层矿区地表沉陷规律的差异,给出了差异产生的内在原因。在沿空巷道围岩-充填体稳定性及围岩变形规律方面,开展了井下的现场实测。采用钻孔成像装置对矿井12307工作面回风巷和运输巷进行了钻孔成像观测,获取了采动影响下部分上覆岩层破坏状态及裂隙场的发育特征;开展了沿空巷道围岩-充填体应力-应变现场监测,得出了沿空巷道和回风巷围岩移动变形和应力分布规律、充填体变形及载荷分布和内部应力传递规律。监测结果表明:工作面一次采动影响下,运输巷底鼓量普遍大于顶板下沉量,巷道顶板浅部岩层受影响较大,主要影响范围在巷道顶板浅部2m范围以内;留巷期间巷道顶板上覆岩层破断回转,老顶下沉对巷道顶板浅部岩层影响较大,引起巷道围岩发生剧烈变形,使巷道顶板裂隙进一步发育贯通,造成岩层层面进一步破碎,深部岩体裂隙进一步张开与发育,回风巷对应运输巷同一位置顶板更加破碎,顶板变形加大;二次采动使回风巷道围岩残余支承压力与本区段超前支承压力相互叠加,导致巷道围岩应力急剧增高,加大了对巷道顶板的破坏,浅部岩层破碎加剧,顶板的裂隙发育进一步加大,顶板离层增多下沉量大,巷道收敛变形量大于一次采动影响,主要影响范围为顶板以上4m范围以内,4m以外范围影响较小;充填体内部应力监测最大数值为5MPa,但大部分未超过充填体本身实验强度4.2MPa,虽然产生了横向变形和纵向变形,但没有引起充填体的破坏,横向变形只是在充填体的局部表现较为明显,由于采用了锚栓加固整体性较好,而采空区矸石和巷道侧点柱改变了充填体受力状态,提高了充填体的稳定性,对顶板的适应性较强,对顶板的支护作用较好。通过研究,改善围岩支护状态,可减少顶板变形,为试验煤矿区后续沿空留巷支护、设计、参数优化和现场实施等提供理论支持和技术参考,为高效留巷提供技术保障。在覆岩运移规律方面,在相似材料配比实验的基础上,开展了物理模拟实验。采用包括光纤光栅传感器、近景摄影测量和2D-DIC在内的多源监测手段和方法,对云驾岭煤矿采动覆岩运移规律和沉陷机理进行了研究,并对上述监测方法实施了交叉验证。为了便于对比分析覆岩的移动变形特征以及裂隙场的发育规律,体现实验结果的差异,决定在一个实验平台上同时铺设两个相似模型,模型一和模型二的地层数量、煤层开采厚度、各岩层尺寸均相同,唯一不同的是关键层位置,以便能够体现覆岩沉陷过程中关键层对裂隙场发育高度的不同控制作用。每个模型的实验结果表明,关键层对上覆岩层具有显著的控制作用,主、亚关键层自身下沉量与所处模型位置关系密切,模型上覆岩层垮落高度、裂隙发育程度与关键层自身厚度和强度相关。四种监测手段各有优势且具有较高的监测精度,其中光纤光栅传感器监测曲线峰值可作为关键层破断的依据,2D-DIC能够动态获取研究区域的全时域位移场和形变场,为开展相似材料模拟实验提供了全新的观测技术手段和方法。采用FLAC3D有限差分程序,对不同充填体尺寸进行优化,对宏观采场矿压显现进行数值模拟。通过模拟,在保证对顶板正常支护的条件下考虑采用最为经济的留巷方式。结果表明:工作面开采完毕后采空区底板主要表现为剪切破坏,中部区域表现为剪切拉伸破坏,剪切破坏最大深度在采空区以下30m左右。侧向支承压力对下帮实体煤主要影响范围在距采空区一侧10m以内,主要表现为剪切破坏。下区段工作面开采后煤帮、充填体及上区段工作面保护煤柱共同形成高应力大、小结构;高水材料充填体宽度为3.0m时,留巷期间承载性能较高,与巷道围岩的协同性高,从而有利于改变覆岩的破坏状态和对地表变形的破坏;充填体宽度为2.5m和2.0m时,留巷期间充填体承载性能较低,充填体变形量大而稳定性差,对巷道围岩控制难度加大。沿空留巷巷旁高水材料充填完成后,选择恰当时机切除巷旁靠近采空区一侧顶板有益于留巷围岩的稳定。地表沉陷时空预测和参数反演方面,提出采用正态分布时间函数进行地表动态沉陷预测,构建了基于正态分布时间函数的地表沉陷动态预测数学模型,分析了曲线形态系数对预测精度的影响以及正态分布时间函数的时空完备性,证实了该数学模型在地表下沉、下沉速度和加速度与地表沉陷过程的时空变化特征相一致。针对云驾岭煤矿非常规地表移动观测站,采用空间曲面拟合方法,求取了地表沉陷预计参数和时间参数,并依据现场监测数据对模型进行了分析,与云驾岭煤矿实测数据和辛置煤矿实测数据进行工程验证,结果表明预测精度满足工程需求,证实了基于正态分布时间函数地表沉陷预测模型能够进行厚松散层条件下地表移动和变形预测。基于上述预测模型,利用Matlab开发平台,研发了界面友好、适时成图的地表沉陷预测信息系统,该系统包含点预测模块、线预计模块、三维空间地表沉陷预计模块以及参数反演模块,利用该系统能够对采煤诱发的地表沉陷进行科学预测。
[Abstract]:The problem of mining, especially coal mining, has been a long history. A series of mining subsidence caused by the mining of ore body under different geological conditions is complicated and changeable, and the mining subsidence caused by large coal mining under thick loose layer is more prominent, and then the surface subsidence range and subsidence caused by the mining are caused by mining. The time and space prediction of the location of the amount and subsidence is more difficult. At the same time, it has a significant influence on the development characteristics and laws of the overlying rock fracture field, displacement field and stress field. Because mining subsidence seriously affects the safety of coal mine production, causing environmental damage and affecting the mining of coal resources. Law, the law of overlying rock movement and the research on the synergistic relationship between the filling body and the surrounding rock, will help to improve the production of coal resources, prolong the service life of the mine, prevent or reduce the mine geological disasters, promote the safety of the coal industry, scientific and sustainable development and the benign ecological cycle of coal mining area. In fact, the mining subsidence phenomenon is actually exploited. It is the concrete manifestation of the movement of overlying rock to the surface, and the movement of overlying rock is the motive force and cause of the surface subsidence. Therefore, the research and exploration of the movement of the mining overlying strata, the law of fracture development, the stress strain characteristics and so on should be studied and explored from the source and mechanism of the law of surface movement and deformation. The engineering geological conditions of the three mining area are the background of the study. The typical geological mining conditions are that the thickness of the loose layer is large, and the average thickness of the Quaternary loose layer is generally 90-150m, the average 120m, the mining of 2# coal seam, the average thickness of the coal seam 4.2m, and the coal seam dip angle. The paper adopts the field monitoring, theoretical analysis, laboratory test and numerical simulation phase. Combined with the comprehensive research method, the stress and strain law of the surrounding rock, the deformation of the overlying strata and the development of the fracture field, the deformation and subsidence of the ground surface caused by the coal mining are studied, and the three-dimensional synergistic study of the underground stope - overlying rock and the surface is realized. On the ground surface subsidence law under the scattered layer, the surface movement observation station is set up. The surface subsidence caused by the 12303 working face and the 12305 working face mining in the three mining area of the Yun Jialing coal mine is systematically monitored. The whole monitoring process has carried out a total of 11 times and 5 comprehensive observations, and the possible shadow produced by the surrounding work is analyzed. Based on the field measured data, the characteristics of Z line and U line subsidence, tilt, curvature, horizontal movement and horizontal deformation after mining of two working faces are analyzed. The parameters of the end state of the ground surface are determined, the dynamic deformation characteristics of the surface of the U line and the Z line after the mining of the two working face are analyzed, and the progress of the working face and the most ground surface are determined. The position relation of large sinking point is studied. The change law of subsidence velocity of ground surface after 12303 working face and 12305 working face is studied. The maximum subsidence speed lag distance, the maximum sinking velocity lag angle, the advance influence distance and the forward influence angle are obtained. The empirical formula of the maximum subsidence velocity of the surface is determined by the regression analysis. The angle, the maximum sinking angle, the sinking coefficient and so on are compared and analyzed the difference of the surface subsidence law of the thick loose strata in the Kailuan mining area, the Kailuan mining area and the Kailuan mining area. The internal reasons for the difference are given. The field measurement of the underground is carried out in the stability of the surrounding rock filling body and the deformation law of the surrounding rock, and the borehole imaging is used. The device has carried out borehole imaging observation on the back alley and transportation lane of the 12307 working face of the mine. The damage state of the overlying strata and the development characteristics of the fractured field are obtained under the influence of mining, and the field monitoring of the stress strain of the surrounding rock filling body along the goaf is carried out, and the deformation and stress distribution law of the surrounding rock in the goaf and the return alley are obtained, and the distribution of the stress distribution is obtained. The deformation of the fill and the load distribution and the law of internal stress transfer. The monitoring results show that under the impact of the first mining face, the bottom of the roadway is generally larger than the roof subsidence, the shallow rock strata in the roof of the roadway are greatly affected, the main influence range is within the 2m range of the shallow part of the roadway roof, and the overlying strata on the roof of the roadway are broken and broken in the roadway. The roof subsidence has a great influence on the shallow rock strata in the roof of the roadway, causing the drastic deformation of the roadway surrounding rock and the further development of the roadway roof fissure, resulting in further fragmentation of the rock layer, further opening and development of the deep rock fracture, the back air lane is more broken and the roof deformation increases with the same position of the transportation lane, and the two mining is made back. The residual support pressure of the surrounding rock of the wind tunnel is superposed with the advance supporting pressure of the section, which leads to a sharp increase in the stress of the roadway surrounding rock, increasing the damage to the roof of the roadway, intensifying the breakage of the shallow strata, increasing the crack development of the roof further, increasing the subsidence of the roof separation layer, and the main influence of the convergence and deformation of the roadway greater than the effect of a mining. The range is less than 4m range above the top plate and smaller outside the 4m. The maximum value of internal stress monitoring of the filling body is 5MPa, but most of the experimental strength of the filling body does not exceed the experimental strength of the filling body 4.2MPa. Although the transverse deformation and longitudinal deformation are produced, the filling body is not destroyed, and the lateral deformation is only obvious in the local performance of the filling body. Due to the better integrity of the anchorage reinforcement, the gangue in the goaf and the side point column of the roadway have changed the stress state of the filling body, and the stability of the filling body is improved, the adaptability of the roof is stronger and the supporting function of the roof is better. Through the study, the supporting state of the surrounding rock can be improved and the deformation of the roof can be reduced. Support, design, parameter optimization and field implementation provide theoretical support and technical reference, and provide technical support for efficient retention of lanes. On the basis of the law of overburden migration, physical simulation experiments are carried out on the basis of similar material ratio experiments. Multi source monitoring methods, including fiber Bragg grating sensors, close range photogrammetry and 2D-DIC, are used. Methods the migration law and subsidence mechanism of mining overlying rock in Yun Jialing coal mine are studied and cross validation is carried out on the above monitoring methods. In order to compare and analyze the characteristics of the movement and deformation of the overlying rock and the law of the development of the fracture field, the difference of the experimental results is reflected, and two similar models are laid on an experimental platform at the same time. The number of the formation of model 1 and model two, the thickness of coal seam mining, the size of each rock layer are the same, the only difference is the key layer position, so that it can reflect the different control effects of the key layer on the development height of the fractured field during the process of overlying subsidence. The subsurface subsidence of the sub key layer is closely related to the position of the model. The height of the overlying strata falls, the degree of fracture development is related to the thickness and strength of the key layer itself. The four monitoring means have advantages and have high monitoring accuracy. The peak value of the fiber Bragg grating sensor monitoring curve can be used as the basis for breaking the key layer, and 2D-DIC can be used. The whole time domain displacement field and deformation field of the research area are dynamically obtained. The new observation technique and method are provided for the simulation experiment of similar materials. The FLAC3D finite difference program is used to optimize the size of different filling bodies and to simulate the macroscopic mining pressure. Through simulation, the normal support of the roof is ensured. The results show that the bottom floor of the goaf is mainly characterized by shear failure, and the central region is characterized by shear tensile failure, and the maximum depth of shear failure is about 30m below the goaf. The main impact of lateral support pressure on the bottom solid coal is on the side of the goaf side. Under 10m, the main performance is shear failure. The coal help after mining under the working face of the lower section, the filling body and the protective coal pillar of the working face of the upper section together form a high stress and small structure. When the width of the filling body of the high water material is 3.0m, the bearing performance is high and the coordination of the roadway surrounding rock is high, which is beneficial to the change of the failure state of the overlying rock. When the width of the filling body is 2.5m and 2.0m, the bearing capacity of the filling body is low, the deformation of the filling body is large and the stability is poor, and the difficulty in controlling the surrounding rock is more difficult. After the filling of the high water material along the roadside lane along the goaf, the choice of the appropriate time to excision the side roof near the goaf near the goaf is beneficial to the stability of the surrounding rock. In terms of spatial and temporal prediction and parameter inversion of surface subsidence, a normal distributed time function is proposed to predict the dynamic subsidence of the surface. A mathematical model of dynamic prediction of surface subsidence based on normal distribution time function is constructed, and the influence of the curve shape coefficient on the prediction accuracy is analyzed and the temporal and spatial completeness of the normal distribution time function is confirmed. The mathematical model is sinking in the surface, the velocity and acceleration of the subsidence are in accordance with the temporal and spatial variation characteristics of the surface subsidence. The prediction parameters and time parameters of the surface subsidence are obtained by using the spatial surface fitting method, and the model is analyzed according to the field monitoring data. The measured data of the Yun Jialing coal mine and the measured data of the coal mine are verified by engineering. The results show that the prediction accuracy meets the needs of the project. It is proved that the surface subsidence prediction model based on the normal distribution time function can predict the surface movement and deformation of the surface under the condition of thick loose layer. Based on the prediction model, the Matlab development platform is developed. The surface subsidence prediction information system is friendly and timely. The system includes the point prediction module, the line prediction module, the 3D space surface subsidence prediction module and the parameter inversion module, which can be used to predict the surface subsidence induced by coal mining scientifically.

【学位授予单位】：中国矿业大学(北京)
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TD325

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