北京市平原区构造型地裂缝蕴发机理研究

发布时间：2018-06-08 11:35

本文选题：北京市 + 地裂缝　；参考：《长安大学》2017年硕士论文

【摘要】：近些年来,北京市平原区的地裂缝活动趋于频繁,由此引发的地面破坏愈加严重。因此,搞清楚该区地裂缝成因及其发育机制,对北京市地裂缝的防灾减灾工作具有重要的理论和工程现实意义。在前人研究基础上,本文对北京市平原区地裂缝进行了详细的野外调查,并结合数值模拟,对该区域构造活动条件下的地裂缝分布、发育及成因机制进行了分析研究。取得主要结论如下:1、北京市平原区地裂缝发育分布范围虽然较广,但地表分布具有一定规律性。地裂缝大多顺断裂带发育分布,或在断裂带两侧附近,地裂缝走向与断裂的走向基本一致;少部分地裂缝发育分布于沉降漏斗边缘;地裂缝在平面上大多呈带状密集展布,断续延伸;顺地裂缝带多发育串珠状塌陷坑;地裂缝具有明显三维活动性,但以垂直活动为主。2、北京市平原区地裂缝总体上可分为构造型、超采地下水型和其他因素型多种成因,但构造活动因素对地裂缝发育起主导控制作用。其中,构造型地裂缝主要有高丽营地裂缝带、顺义地裂缝带、房山地裂缝带与庙卷村地裂缝带;超采地下水型地裂缝主要有羊房村地裂缝;其他因素型地裂缝有昌平南新地裂缝带,具体包括平谷地裂缝,通州地裂缝。3、数值模拟结果表明:1)在区域拉张应力作用下,在基底断裂上下两盘存在明显的位移错动和应力、应变集中现象,其影响已通达致地表,由此导致了断裂上覆土体的变形破坏,进而发育成地表裂缝;此外,由于断裂的存在,浅地表土层位移和应力应变分布比较复杂,因而在局部地方又出现次级应力、应变集中带,这些地段也为地裂缝的发育提供了构造应力场条件。2)由于断裂两盘存在明显的走滑错动,因而在断裂转折、端点以及断裂相交处,应力集中明显,对应的这些地段土层往往导致变形,并成为地裂缝容易发生的危险区域。3)土体在自重应力作用下,由于上下盘地层厚度差异,沿断裂方向会存在一个初始的塑性变形带。在垂直错动和水平拉张的持续作用下,主塑性变形始于基岩与土体交界面,并随着垂直错动和水平拉张量不断增大,不断向四周扩展。当垂直错动量达到一定值时,地表出现塑性变形带,并随着垂直错动和水平拉张的持续作用,而不断向四周扩展,并直到与始于基岩与土体交界面的塑性变形带相互连通。次级塑性变形带扩展规律与主变形带相同,只是其倾向与主塑性变形带相反。4)主塑性变形带变形主要受垂直错动和水平拉张影响,垂直错动对于主塑性变形带影响更大,次级塑性变形带主要受水平拉张作用影响。主塑性变形带的变形强度远大于地表次级塑性变形带的变形强度。
[Abstract]:In recent years, the ground fissures in the plain area of Beijing tend to be frequent, and the ground damage is becoming more and more serious. Therefore, it is of great theoretical and engineering significance to understand the causes and development mechanism of ground fissures in this area for the disaster prevention and mitigation of ground fissures in Beijing. Based on the previous studies, this paper makes a detailed field investigation on the ground fissures in the plain area of Beijing. Combined with the numerical simulation, the distribution, development and genetic mechanism of the ground fissures under the conditions of tectonic activity in this area are analyzed and studied. The main conclusions are as follows: 1. Although the distribution range of ground fissures in the plain area of Beijing is wide, the surface distribution has certain regularity. Most of the ground fissures are distributed along the fault zone, or near the two sides of the fault zone, the strike of the ground fissure is basically the same as the strike of the fault, a few of the ground fissures are distributed on the edge of the subsidence funnel, and most of the ground fissures are distributed in the plane. The ground fissures have obvious three-dimensional activity, but the vertical activity is the main .2. the ground fractures in Beijing plain area can be divided into tectonic type, in general, the ground fissures in the plain area of Beijing can be divided into tectonic type, and the ground fissure in the plain area of Beijing can be divided into two types as a whole. There are many kinds of causes of overexploitation groundwater type and other factor type, but tectonic active factors play a dominant role in controlling the development of ground fracture. Among them, there are main structural cracks in Koryo camp, Shunyi, Fangshan and Miaohucun, and the overdeveloped groundwater cracks are mainly Yangfang Village. Other factor types of ground fissures are the South Changping New ground fracture Zone, including Pinggu ground fissure, Tongzhou ground fissure .3. the numerical simulation results show that there are obvious displacements and stresses in the upper and lower plates of the basement fault under the action of regional tensile stress. The effect of strain concentration has reached the surface of the earth, which leads to the deformation and failure of the fractured overlying soil, and then develops into the surface crack. In addition, because of the existence of the fracture, the distribution of displacement and stress and strain in the shallow soil layer is quite complex. As a result, secondary stresses and strain concentration zones appear locally, which also provide tectonic stress field conditions for the development of ground fissures. At the end points and at the intersection of faults, the stress concentration is obvious. The corresponding soil layers in these sections often lead to deformation and become the dangerous area. 3) under the action of gravity stress, the thickness of the upper and lower layers of soil is different. There will be an initial plastic deformation zone along the fracture direction. Under the continuous action of vertical dislocation and horizontal tension, the principal plastic deformation begins at the interface between bedrock and soil, and with the increase of vertical dislocation and horizontal tensile Zhang Liang, the main plastic deformation continues to expand around. When the vertical dislocation momentum reaches a certain value, the plastic deformation zone appears on the surface of the earth, and with the continuous action of vertical dislocation and horizontal tension, it expands around the surface and is connected with the plastic deformation zone which begins at the interface between the bedrock and the soil. The propagation law of secondary plastic deformation zone is the same as that of main deformation zone, but its tendency is opposite to that of main plastic deformation zone. 4) the deformation of main plastic deformation zone is mainly affected by vertical dislocation and horizontal tension, and vertical dislocation has more influence on principal plastic deformation zone. The secondary plastic deformation zone is mainly affected by horizontal tension. The deformation strength of the main plastic deformation zone is much higher than that of the surface secondary plastic deformation zone.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P642.2

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