降雨和地震影响下碎石土边坡的稳定性分析

发布时间：2018-05-06 19:04

本文选题：碎石土边坡 + 稳定性　；参考：《兰州交通大学》2013年硕士论文

【摘要】：边坡稳定性研究至今仍是岩土工程界一个热点研究方向，也是一项复杂而未能很好解决的技术难题。边坡的稳定受很多因素的影响，如降雨、地震、人工开挖、各种荷载作用、岩土体工程性质等，而降雨和地震则是最主要也是较为常见的两个因素，至今仍是边坡稳定性研究的重点。所以，对边坡与降雨或地震之间的关系进行分析研究对于边坡失稳的预防与整治将起到非常重要的作用。根据降雨和地震影响下边坡稳定性的研究现状以及尚未解决的问题，本文以楼房山碎石土滑坡为工程背景，建立FLAC3D三维数值模型，通过计算结果来分析降雨和地震对碎石土边坡稳定性的影响及其破坏机理。本文主要研究内容包括以下几方面：（1）以均质边坡为例，用FLAC3D强度折减法分别计算了单因素变化条件下边坡的稳定系数值，采用敏感性分析法分析各影响因素对边坡稳定性的影响程度，得到各因素对碎石土边坡稳定性影响程度的大小关系为：内摩擦角边坡坡角粘聚力土体密度。（2）建立楼房山碎石土滑坡FLAC3D数值计算模型，，分析了降雨影响下边坡的应力场、位移场、塑性区及剪应变增量分布规律，研究了边坡在降雨影响下的失稳破坏机理。结果表明，在降雨条件下，碎石土边坡的稳定性随着含水率的增加呈先缓慢减小后急剧减小的特征，并存在明显的临界特性，含水率11.3%是边坡稳定性变化的临界点。（3）利用FLAC3D数值计算模型，分析了地震作用下边坡的应力场、位移场、塑性区及剪应变增量分布规律，研究了边坡在地震荷载作用下的失稳破坏机理。结果表明，在很微小的地震荷载作用下，碎石土边坡就会发生失稳，且边坡破坏程度随地震水平加速度的增加而增大；碎石土边坡在地震作用下主要发生受压破坏，只在边坡坡顶部位出现小面积的拉应力区域，此部位发生张拉破坏；而在碎石土边坡底部，由于其主应力方向发生改变,土体处于双向受压状态,发生剪切破坏。（4）利用FLAC3D数值计算模型，分析降雨和地震共同作用下边坡的应力场、位移场、塑性区及剪应变增量分布规律，研究了边坡在降雨和地震共同作用下的失稳破坏机理，说明当地震与降雨共同作用时，边坡的稳定性较地震或降雨单独作用时要低；在含水率保持不变的情况下，随着地震荷载的增加，碎石土边坡的稳定性在逐渐降低；在地震水平加速度保持不变的情况下，随着含水率的增加，碎石土边坡的稳定性在逐渐降低。本文通过分析楼房山碎石土滑坡工程在降雨与地震及降雨和地震共同作用下边坡的失稳破坏机理，充分揭示降雨入渗和地震震动引起碎石土边坡破坏的模式及其发展过程，给出在降雨与地震影响下碎石土边坡稳定性的变化特点，从而为预防和整治边坡失稳提供更为适用的经验。
[Abstract]:Slope stability research is still a hot research direction in geotechnical engineering field, and it is also a complicated and unsolved technical problem. The stability of slope is affected by many factors, such as rainfall, earthquake, artificial excavation, various loads, engineering properties of rock and soil, etc. Rainfall and earthquake are the two most common factors. Up to now, it is still the focus of slope stability research. Therefore, the analysis and study of the relationship between slope and rainfall or earthquake will play a very important role in slope instability prevention and remediation. According to the present situation of slope stability under the influence of rainfall and earthquake and the unsolved problems, this paper takes the debris landslide of building mountain as the engineering background, and establishes the FLAC3D three-dimensional numerical model. The influence of rainfall and earthquake on the stability of gravel slope and its failure mechanism are analyzed. The main contents of this paper include the following aspects: 1) taking homogeneous slope as an example, FLAC3D strength reduction method is used to calculate the slope stability coefficient under the condition of single factor change, and the sensitivity analysis method is used to analyze the influence degree of each influencing factor on slope stability. The influence of various factors on the stability of gravel slope is obtained as follows: internal friction angle slope angle cohesion soil density. (2) the FLAC3D numerical calculation model of rockfill landslide is established, and the stress field, displacement field, plastic zone and shear strain increment distribution law of slope under the influence of rainfall are analyzed, and the failure mechanism of slope under the influence of rainfall is studied. The results show that the stability of macadam slope decreases slowly and then decreases sharply with the increase of moisture content under rainfall condition, and has obvious critical characteristics. The critical point of slope stability change is water content of 11.3%. 3) the stress field, displacement field, plastic zone and shear strain increment distribution of slope under earthquake are analyzed by using FLAC3D numerical model, and the failure mechanism of slope under earthquake load is studied. The results show that, under the action of very small earthquake load, the gravel slope will lose stability, and the failure degree of the slope will increase with the increase of horizontal acceleration of the earthquake, and the crushed soil slope will mainly be destroyed under the earthquake, and the failure degree of the gravel slope will increase with the increase of the horizontal acceleration of the earthquake. Only a small area of tensile stress occurs at the top of the slope, but at the bottom of the gravel slope, the soil is subjected to biaxial compression and shear failure because of the change of the direction of the principal stress. (4) the stress field, displacement field, plastic zone and shear strain increment distribution of slope under the action of rainfall and earthquake are analyzed by using FLAC3D numerical calculation model, and the failure mechanism of slope instability under the joint action of rainfall and earthquake is studied. The results show that the slope stability is lower when the earthquake and rainfall work together than the earthquake or rainfall alone, and the stability of the gravel slope decreases gradually with the increase of the seismic load when the water content remains constant. With the increase of water content, the stability of gravel slope decreases gradually when the horizontal acceleration of earthquake remains unchanged. In this paper, the failure mechanism of slope instability caused by rainfall, earthquake, rainfall and earthquake is analyzed, and the failure mode and development process of gravel slope caused by rainfall infiltration and earthquake vibration are fully revealed. The variation characteristics of slope stability of gravel soil under the influence of rainfall and earthquake are given, thus providing more suitable experience for preventing and rectifying slope instability.
【学位授予单位】：兰州交通大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU43

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