高烈度地震区黄土滑坡稳定性与防治技术研究

发布时间：2018-10-23 18:41

【摘要】：我国的西北黄土地区具有非常特殊的地质构造背景，该区黄土滑坡灾害频发，且大部分处于高烈度地震区。本文以甘肃中南部地区为研究区，研究该区黄土滑坡所处的地质环境和特征，通过大量的地质调查、室内试验、理论计算和数值模拟等方法，对研究区黄土滑坡的特征、地震稳定性和防治技术进行了系统的研究，取得了以下研究成果： 1、对研究区典型黄土滑坡的特征和形成机制进行了研究，结果表明，三家地滑坡为巨型黄土-泥岩老滑坡，坡体不良的地质结构和陈李沟泥石流对滑坡前缘的长期侵蚀是老滑坡形成的主要因素，“5.12”汶川地震诱发了滑坡前缘大规模复活滑动而后缘由于受前部滑动牵引而产生贯通裂缝，为牵引式滑坡。 2、针对典型黄土滑坡滑带土的静、动力性质进行了直剪试验、静三轴和动三轴试验，结果表明，九州和三家地滑坡滑带土粘聚力与内摩擦角的峰值和残余值均随含水量的增大而减小；滑带土动弹性模量随动应变的增大而减小，阻尼比随动应变增大而缓慢增大,在很小范围内波动，动粘聚力和动内摩擦角随含水量的增大而减小。 3、考虑5类16项影响因素指标，建立了地震作用下黄土滑坡稳定性模糊综合评价模型，，基于岩土力学参数和地震加速度的随机性和模糊性，提出了地震作用下黄土滑坡稳定性的可靠度与模糊随机可靠度计算方法，将建立的模型应用到汶川震区三家地滑坡的地震稳定性分析中，并利用拟静力法对地震工况下滑坡的稳定系数进行了计算。这几种评价方法的结果均表明地震作用下三家地滑坡处于欠稳定状态。 4、利用FLAC3D软件动力分析模块对三家地滑坡在地震作用前后的稳定性进行了数值模拟分析，结果表明，地震前三家地滑坡处于稳定状态，地震作用下滑坡整体上处于欠稳定状态，滑坡体前部位移和剪应变增量明显增大。 5、利用正交试验法和改进的灰色关联法，分析了三家地滑坡稳定性主要影响因素的敏感性，结果表明，地震作用是仅次于滑带土内摩擦角的影响因素，随着地震烈度的增大，滑坡稳定系数的减小趋势增大。 6、对黄土滑坡的主要防治措施进行了分析，研究了影响黄土滑坡综合治理方案决策的主要因素指标，提出了黄土滑坡治理方案评价指标的优化赋权计算方法，并建立了黄土滑坡治理方案优选模型。确定了三家地滑坡的最优治理方案为：前缘回填反压工程+沟道泥石流治理工程+排水工程。
[Abstract]:The loess region in northwest China has a very special geological tectonic background. The loess landslide disasters occur frequently in this area and most of them are located in the high intensity earthquake area. In this paper, the geological environment and characteristics of loess landslide in central and southern Gansu are studied, and the characteristics of loess landslide in the study area are analyzed by means of a large number of geological investigation, laboratory tests, theoretical calculation and numerical simulation. The seismic stability and prevention techniques are systematically studied, and the following results are obtained: 1. The characteristics and formation mechanism of typical loess landslides in the study area are studied. The results show that, Sanjiadi landslide is a giant loess-mudstone landslide. The poor geological structure of slope body and the long-term erosion of the front edge of the landslide caused by Chen Ligou debris flow are the main factors leading to the formation of the old landslide. The "5.12" Wenchuan earthquake induced the massive resurrection of the landslide front and the posterior edge of the landslide, which was caused by the front sliding traction to produce a through crack, which is a traction landslide. 2. In view of the static state of the soil in the typical loess landslide slide zone, Direct shear test, static triaxial test and dynamic triaxial test are carried out. The results show that the peak value and residual value of cohesive force and internal friction angle decrease with the increase of water content in the slip zone of Jiuzhou and Sanjia landslide. The dynamic elastic modulus of the sliding zone soil decreases with the increase of the strain, and the damping ratio increases slowly with the increase of the following strain, and fluctuates in a very small range. The dynamic cohesive force and dynamic internal friction angle decrease with the increase of water content. Considering 5 kinds of 16 factors, a fuzzy comprehensive evaluation model of loess landslide stability under earthquake is established. Based on the randomness and fuzziness of geotechnical parameters and seismic acceleration, a method for calculating the reliability and fuzzy random reliability of loess landslide stability under earthquake is presented. The established model is applied to the seismic stability analysis of the landslide in Wenchuan earthquake area, and the stability coefficient of the landslide under the earthquake condition is calculated by using the pseudostatic method. The results of these methods show that the three landslides are in an unstable state. 4. The stability of the three landslides before and after the earthquake is simulated and analyzed by using the dynamic analysis module of FLAC3D software. The results show that the landslide is in a stable state before the earthquake, and the landslide is in an unstable state as a whole under the earthquake. The increment of displacement and shear strain in front of landslide is obviously increased. 5. By using orthogonal test method and improved grey correlation method, the sensitivity of the main factors affecting the stability of the landslide is analyzed. The results show that, Seismic action is second only to the internal friction angle of sliding zone soil. With the increase of seismic intensity, the decreasing trend of landslide stability coefficient increases. 6. The main prevention measures of loess landslide are analyzed. This paper studies the main factors influencing the decision-making of the comprehensive control scheme of loess landslide, puts forward the optimization and weighting calculation method of the evaluation index of the loess landslide control scheme, and establishes the optimal selection model of the loess landslide control scheme. The optimal treatment scheme of three landslides is as follows: the drainage project of gully debris flow treatment in the backfill and back pressure project of the leading edge.
【学位授予单位】：长安大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU444;P642.22

【参考文献】