基底起伏地裂缝演化时空特征试验研究
发布时间：2018-12-18 03:58
【摘要】：随着国民经济快速发展,我国多个地区地下水资源遭到过量开采,导致了严重的地面沉降,而不均匀沉降又诱发了大量地裂缝,造成了严重的环境问题和重大的经济财产损失。因此,深入研究考虑三维地质结构的土体不均沉降与地裂缝的成灾机理和发育过程具有十分重要的科学价值和实际意义。本文以苏锡常地区地裂缝为研究背景,对基底起伏(潜山)和断裂构造发育的厚层不均匀软粘土差异沉降引起的土体裂缝的演化特征进行了试验研究,通过电位、电流、视电阻率、渗流和变形等信息的监测对地裂缝发育演化的动态过程进行了分析。无锡市锡北镇光明村地裂缝位于新华夏第二隆起带和秦岭东西向复杂构造带的交接部位,存在着多条平行的由南向北倾斜的基底隆起构造,基岩面起伏较大。现场地质调查和室内分析均表明该地裂缝主要发育在基岩隆起区和基岩面形态变化较大的区域,基底构造对地裂缝的形成和演化有着显著的控制性影响。基底孤立潜山与梁式起伏的土体失水开裂试验表明:土体失水开裂过程可划分为开裂前I、快速开裂II和开裂停滞III三个阶段;裂缝的发育演化受模型边界和基底起伏的显著影响,在快速开裂II-1阶段,裂缝主要发育在模型边界部位,II-2阶段,裂缝主要在基底起伏影响范围内发育,在III阶段,尽管土体表面开裂仍在发生,裂缝发育的整体格局已经不再发生显著变化;从裂缝形态看,后期裂缝主要与前期裂缝垂直相交,特别是在基底起伏范围内和模型边界区域。基于网络分布式并行电法,对土体开裂的动态过程进行了反演分析,反演结果与观察结果吻合较好。以无锡市锡北镇光明村地裂缝为工程背景进行了土体不均匀沉降诱导的地裂缝试验,在对试验模型中不同部位土体的地电响应特征(自然电位、一次场电位、激励电流、视电阻率)和表面沉降位移监测的基础上,通过分析不均匀沉降与地裂缝发育演化特征获得了以下认识:土体中电位、电流和电阻率的变化与土体含水量密切相关,随着土体中含水量的改变,自然电位、一次场电位、激励电流和视电阻率发生急剧变化;不均匀沉降导致土体中裂缝的产生,NDPGES反演信息和沉降观测值均表明在曲线曲率值较大位置容易产生不均匀沉降和裂缝,不均匀沉降的程度越大,地裂缝的长度、宽度、深度也会越大。
[Abstract]:With the rapid development of the national economy, groundwater resources in many regions of China have been overexploited, resulting in serious land subsidence, but uneven settlement has induced a large number of ground cracks, resulting in serious environmental problems and significant economic property losses. Therefore, it is of great scientific value and practical significance to deeply study the mechanism and development process of the formation and development of the uneven settlement of soil and the ground fissures considering the three-dimensional geological structure. In this paper, based on the background of ground fissures in Suxi-Chang area, the evolution characteristics of soil cracks caused by uneven differential settlement of thick layer soft clay developed in the basement undulation (buried hill) and faulted structures are studied experimentally. The monitoring of apparent resistivity, seepage and deformation is used to analyze the dynamic process of ground fracture development and evolution. The ground fissures in Guangming Village, Xibei Town, Wuxi City, are located at the junction of the second uplift zone of Xinhuaxia and the complex tectonic belt of the east west direction of Qinling Mountains. There are many parallel basement uplift structures inclined from south to north, and the bedrock surface is fluctuating greatly. Field geological investigation and laboratory analysis show that the cracks in this area are mainly developed in the bedrock uplift area and the area where the bedrock surface morphology changes greatly, and the basement structure has a significant controlling effect on the formation and evolution of the ground fracture. The tests of soil water loss cracking in isolated buried-hill and beam undulating soil show that the process of soil water-loss cracking can be divided into three stages: I before cracking, II with rapid cracking and III with stagnant cracking. The evolution of fractures is significantly affected by the model boundary and basement fluctuation. In the rapid cracking II-1 stage, the fractures mainly develop in the model boundary, in the II-2 stage, in the basement undulation range, and in the III stage. Although the surface cracking of soil is still taking place, the overall pattern of crack development has not changed significantly. From the point of view of fracture morphology, the late fracture mainly intersects vertically with the early fracture, especially in the range of basement fluctuation and the boundary area of the model. Based on the network distributed parallel electrical method, the dynamic process of soil cracking is inversed and analyzed, and the inversion results are in good agreement with the observed results. Based on the ground fissures in Guangming Village, Xibei Town, Wuxi City, the ground fissures induced by uneven settlement of soil were tested. The geoelectric response characteristics (natural potential, primary field potential, excitation current) of different parts of soil in the test model were studied. On the basis of apparent resistivity) and surface subsidence displacement monitoring, the following conclusions are obtained by analyzing the characteristics of uneven settlement and evolution of ground fissures: the changes of potential, current and resistivity in soil are closely related to soil water content. With the change of soil moisture content, the natural potential, primary field potential, excitation current and apparent resistivity change sharply. NDPGES inversion information and settlement observations indicate that uneven settlement and cracks are easy to occur in the larger curvilinear curvature. The greater the degree of uneven settlement, the longer the length and width of the ground crack. The greater the depth, too.
【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】：P642.26
本文编号：2385301
[Abstract]:With the rapid development of the national economy, groundwater resources in many regions of China have been overexploited, resulting in serious land subsidence, but uneven settlement has induced a large number of ground cracks, resulting in serious environmental problems and significant economic property losses. Therefore, it is of great scientific value and practical significance to deeply study the mechanism and development process of the formation and development of the uneven settlement of soil and the ground fissures considering the three-dimensional geological structure. In this paper, based on the background of ground fissures in Suxi-Chang area, the evolution characteristics of soil cracks caused by uneven differential settlement of thick layer soft clay developed in the basement undulation (buried hill) and faulted structures are studied experimentally. The monitoring of apparent resistivity, seepage and deformation is used to analyze the dynamic process of ground fracture development and evolution. The ground fissures in Guangming Village, Xibei Town, Wuxi City, are located at the junction of the second uplift zone of Xinhuaxia and the complex tectonic belt of the east west direction of Qinling Mountains. There are many parallel basement uplift structures inclined from south to north, and the bedrock surface is fluctuating greatly. Field geological investigation and laboratory analysis show that the cracks in this area are mainly developed in the bedrock uplift area and the area where the bedrock surface morphology changes greatly, and the basement structure has a significant controlling effect on the formation and evolution of the ground fracture. The tests of soil water loss cracking in isolated buried-hill and beam undulating soil show that the process of soil water-loss cracking can be divided into three stages: I before cracking, II with rapid cracking and III with stagnant cracking. The evolution of fractures is significantly affected by the model boundary and basement fluctuation. In the rapid cracking II-1 stage, the fractures mainly develop in the model boundary, in the II-2 stage, in the basement undulation range, and in the III stage. Although the surface cracking of soil is still taking place, the overall pattern of crack development has not changed significantly. From the point of view of fracture morphology, the late fracture mainly intersects vertically with the early fracture, especially in the range of basement fluctuation and the boundary area of the model. Based on the network distributed parallel electrical method, the dynamic process of soil cracking is inversed and analyzed, and the inversion results are in good agreement with the observed results. Based on the ground fissures in Guangming Village, Xibei Town, Wuxi City, the ground fissures induced by uneven settlement of soil were tested. The geoelectric response characteristics (natural potential, primary field potential, excitation current) of different parts of soil in the test model were studied. On the basis of apparent resistivity) and surface subsidence displacement monitoring, the following conclusions are obtained by analyzing the characteristics of uneven settlement and evolution of ground fissures: the changes of potential, current and resistivity in soil are closely related to soil water content. With the change of soil moisture content, the natural potential, primary field potential, excitation current and apparent resistivity change sharply. NDPGES inversion information and settlement observations indicate that uneven settlement and cracks are easy to occur in the larger curvilinear curvature. The greater the degree of uneven settlement, the longer the length and width of the ground crack. The greater the depth, too.
【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】：P642.26
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