大渡河右岸瓦斯沟至冷竹关沟斜坡地震动响应研究

发布时间：2018-03-08 12:06

本文选题：瓦斯沟　切入点：滑坡斜坡地震动响应　出处：《成都理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：我国是一个多山、多地震的国家,而地震是导致斜坡失稳,诱发崩塌、滑坡的一个重要因素。历史上由于地震导致的边坡失稳事例数以万计。在过去的几年中,相继发生了汶川大地震(Ms8.0)、云南鲁甸地震(Ms6.5)、芦山地震(Ms7.0)。说明我国的地震断裂带,尤其是西南地区地震断裂带处于相对活跃的时期。随着我国西部大开发战略的实施,许多大型工程上马,遇到了大量的边坡,尤其是复杂岩质高陡边坡。这些边坡的地震动响应、变形和稳定性问题均十分突出,成为亟待解决的重大问题。因此,研究高陡岩质边坡在地震作用下的地震动响应特征具有较高的科研价值和现实意义。本文主要以瓦斯沟古地震滑坡为研究对象。在查阅相关地质资料,实地野外调查,室内岩石力学试验的基础上,探讨该滑坡的形成条件和成因机制。结合数值模拟对瓦斯沟滑坡进行反演研究,探讨该斜坡在历史地震作用下的运动规律和响应特征。最后通过处理冷竹关斜坡对“11.22”康定地震的监测数据,分析该区斜坡地震动响应特征。主要结论与认识如下:(1)研究区位于川西北,青藏高原东部边缘地带。地貌上属于大渡河深切高山峡谷地貌,出露晋宁—澄江期斜长花岗岩,主要受鲜水河断裂带、龙门山断裂带和大渡河断裂带控制。研究区主压应力方向为NW-NWW向,主张应力方向为NE-NEE向。(2)瓦斯沟滑坡位于大渡河右岸,瓦斯沟南岸。滑坡体平均宽度约400m,纵向长度约700m,平均堆积厚度约120m,方量约3360×104m3,属特大型堆积层滑坡,滑坡堆积物岩性为斜长花岗岩。滑源区为一“凸”型山嘴,三面临空,临空条件好,主要发育4组节理面,局部发育架空的楔形“凹岩腔”。(3)研究区岩石力学试验结果表明,天然状态下该区斜长花岗岩单轴抗压强度约70MPa,动泊松比约0.28,动弹性模量约80.4GPa,内聚力约10MPa,内摩擦角约60°。(4)通过对古地震滑坡的调查及分析,瓦斯沟滑坡与其三面临空的地貌、节理面组合、地震等因素相关。地震的累积效应和触发效应是其斜坡失稳破坏的主要因素。(5)通过DDA数值模拟方法反演地震触发瓦斯沟滑坡全过程研究发现,地震波在从边坡底部向上传播过程中,随高程增加,峰值加速度会得到放大,放大系数最大达1.2倍;在横向面上,从边坡表面向坡体内部,地震波的峰值加速度也会得到放大,其放大倍数较竖直方向上较小。(6)通过冷竹关斜坡6台地震监测仪器对康定Ms6.3级地震监测数据研究,表明冷竹关沟右岸监测点峰值加速度(PGA)明显大于左岸,并且其地震动能量(即阿里亚斯强度)也明显高于左岸,表明右岸的斜坡地震动响应明显强于左岸。加速度反应谱表明场地的阻尼特性不影响地震动响应的曲线特征。地震动响应的强度会随着场地阻尼的增加而降低,但这种变化是趋于收敛的。即其响应强度不会随阻尼的增加无限制下降。由峰值加速度(PGA)及HVSR谱比曲线表明:放大效应受地形地貌条件影响很大。冷竹关右岸单薄山脊的放大效应明显强于左岸中高山斜坡,而位于凸出地形的1#监测点放大效应又明显强于其他监测点,说明多面临空的山体、山体的凸出部位对地震动响应存在明显的放大效应。
[Abstract]:China is a mountainous country, earthquake, and earthquake is the result of slope instability, induced collapse, one of the important factors of landslide. Because of the history of slope earthquake caused instability of tens of thousands of examples. In the past few years, have occurred in the Wenchuan earthquake (Ms8.0), Yunnan Ludian earthquake (Ms6.5), Lushan earthquake (Ms7.0). The earthquake fault belts in China, especially in a relatively active period in Southwest China earthquake fault zone. With the implementation of western development strategy in China, many large-scale projects, met a large number of slope, especially the complex high and steep rock slope. The slope of the response vibration, deformation and stability problems are very prominent, has become a major problem to be solved. Therefore, the research of high steep rock slope under earthquake ground motion response characteristics with high scientific value and practical significance. This paper mainly in the gas channel PALAEOSEISMIC landslide as the research object. On the related geological data, field investigation and indoor rock mechanics test based on the study of the formation conditions and formation mechanism of the landslide. Based on gas landslide inversion study of numerical simulation of the slope movement in the history of earthquake and response characteristics. Finally, the monitoring data the slope of the "11.22" Kangding earthquake by cold shock treatment of bamboo, the response characteristics of the slope. The main conclusions are as follows: (1) the study area is located in the northwest of Sichuan, the edge of the eastern Tibetan Plateau. The landscape belongs to the Dadu river deep mountain canyon, exposed Jinning Chengjiang plagiogranite, mainly by the Xianshuihe fault zone, fault zone of the Longmen mountain and the Dadu River fault zone. The principal compressive stress in study area in NW-NWW direction, the direction of principal tensile stress is NE-NEE. (2) the gas landslide is located in On the right bank of river, wasigou south. The average width of the landslide is about 400m, the longitudinal length of about 700m, the average thickness of about 120m, volume of about 3360 * 104m3, a large landslide, landslide accumulation lithology for plagioclase granite. The source area is a smooth convex spur, three are free, free conditions well, there are mainly 4 groups of joints, the local development of the overhead of the wedge "concave rock cavity". (3) the results of rock mechanics test shows that the study area, the natural state of uniaxial compressive strength of the plagioclase granite is about 70MPa, Poisson's ratio of about 0.28, the dynamic elastic modulus of cohesive force is about 80.4GPa, about 10MPa, the angle of internal friction about 60 degrees. (4) through the investigation and analysis of the ancient landslide, landslide and gas three facing the empty landscape, combined joint, earthquake and other factors. The cumulative effect of earthquake and triggering effect are the main factors of slope failure. (5) through the DDA numerical simulation method The inversion of earthquake triggered landslide gas process study found that seismic wave in the propagation from the bottom of the slope, with elevation increasing, the peak acceleration will be amplified, the amplification coefficient of up to 1.2 times the maximum; in the horizontal plane, from the slope surface to the slope, seismic peak acceleration will be enlarged the magnification of the vertical direction is smaller. (6) the Lengzhuguan slope 6 Taiwan earthquake monitoring instrument of the Kangding Ms6.3 earthquake monitoring data study showed that cold bamboo Guangou right bank monitoring point of peak acceleration (PGA) was significantly higher than that of the left bank, and the seismic energy (i.e. Arias strength) was also significantly higher than that on the left bank, right bank the slope seismic response was stronger than the left bank. The acceleration response spectrum showed that the damping properties of the site does not affect the characteristics of seismic response. The seismic response of the strength will decrease with the increase of damping and the site, but This change is that it tends to converge. The response intensity does not decrease with the increase of damping limit. The peak acceleration (PGA) and HVSR spectral ratio curve shows that the amplification effect by the topography conditions affected. The amplification effect of Lengzhuguan on the right bank of the thin ridge was stronger than the mountain slopes on the left bank of 1#, and in the monitoring points the protruding topography amplification effect is stronger than the other monitoring points, indicating multiple free surfaces of the mountain, protruding parts of the mountain on the ground motion response has obvious amplification effect.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P315.2

【参考文献】