地层结构对斜坡地震动力响应及其失稳机制的影响研究

发布时间：2018-05-07 05:42

本文选题：地震动力响应规律 + 斜坡破坏失稳机制　；参考：《西南交通大学》2016年硕士论文

【摘要】：G318自上海至西藏樟木长达5000多公里,西藏境内G318沿线地质灾害严重,以崩塌、滑坡、泥石流为主,同时发育雪崩、河岸坍塌和冻土冻融。其中林芝到波密段发育有典型的崩塌滑坡等地质灾害,研究地震作用在本段路线引发的次生地质灾害对沿线的灾害防治和公路铁路的建设具有相当重要的作用。本文基于自然基金项目《G318西藏林芝-波密段斜坡动力响应与滑坡启动机理研究》,在广泛了解G318林芝到波密段的滑坡灾害,统计滑坡的主要地层结构类型,建立相应的数值模型,基于该段最典型的地层结构类型,进行地震动力响应的数值模拟计算,对比研究动力响应规律,分析其失稳破坏机制,得到以下研究成果：1、土层斜坡坡面的动力响应规律为随高度增加PGA放大系数随之增大,且一定高度存在极值,坡体PGA放大系数基本呈现垂直放大效应；坡体在震后并未失稳,而是在坡脚发生局部剪切破坏,这可能是研究区土层斜坡失稳破坏的诱因。2、土层—岩层斜坡的失稳破坏状态为：土层为碎石土的斜坡在震后出现了两条潜在滑带,一条在滑体和基岩界面处,另一条则从滑体下10m左右形成一贯通的滑面；土层为冰碛土的斜坡震后在滑体与岩基界面处出现一贯通滑面。斜坡在坡面产生拉裂破坏,在滑体下部坡脚滑带附件产生剪切破坏,土层为碎石土斜坡则在坡顶少量单元产生拉裂破坏。土层—岩层斜坡的动力响应规律为：坡面PGA放大系数随高度增大,且在一定高度存在极值；坡体PGA放大系数表现为匀速的垂直放大效应,且千枚岩斜坡PGA放大系数更大；岩土接触带两侧,土层与岩层的水平位移及加速度表现出明显的差异响应,笔者认为这是导致土层—岩层斜坡多在岩土接触带发生滑动的根本原因,由于岩层与土层差异响应导致变形不协调所致；水平位移及PGA放大系数土层为碎石土的斜坡明显大于土层为冰碛土的斜坡,可见,土层—岩层地层结构斜坡的失稳破坏程度更多受土层类型的控制。
[Abstract]:The length of G318 is more than 5000 kilometers from Shanghai to Tibet, and the geological hazards along G318 in Tibet are serious, such as collapse, landslide, debris flow, avalanche, river bank collapse and frozen soil freezing and thawing at the same time. There are typical geological disasters such as landslides and collapses in Linzhi to Bomi section. The study of secondary geological disasters caused by earthquake action in this section plays an important role in the disaster prevention and control along the route and the construction of highway and railway. Based on the research of slope dynamic response and landslide start-up mechanism of G318 Linzhi-Bomi section in Tibet, this paper, based on the natural fund project < G318, Tibet, has established a numerical model on the basis of a broad understanding of the landslide disasters in the G318 Linzhi to Bomi section, the main strata structure types of the landslide, and the corresponding numerical model. Based on the most typical stratum structure type, the seismic dynamic response is numerically simulated, the dynamic response law is compared and the failure mechanism is analyzed. The following research results are obtained: 1. The dynamic response law of the slope surface is that the PGA magnification coefficient increases with the height increasing, and there exists an extreme value at a certain height, and the PGA magnification factor of the slope body presents the vertical amplification effect basically, and the slope body does not lose stability after the earthquake. But local shear failure occurs at the foot of the slope, which may be the inducement of the instability of the soil slope in the study area. The failure state of the soil layer slope is as follows: there are two potential slip zones after the earthquake on the slope whose soil layer is gravel soil. One is at the interface between the sliding body and the bedrock, the other is formed a through slip surface from the slip body about 10 m below, and the slope of the soil layer is the moraine soil which appears a penetrating slip surface at the interface between the sliding body and the rock foundation after the earthquake. The slope has tensile failure on the slope, shear failure at the bottom of the slip zone, and tensile failure on the slope with a small number of elements at the top of the slope. The dynamic response of soil and rock slopes is as follows: the PGA magnification coefficient of slope surface increases with height, and there exists an extreme value at a certain height, the PGA magnification factor of slope body shows the vertical amplification effect of uniform velocity, and the PGA magnification factor of phyllite slope is larger than that of phyllite slope. On both sides of the contact zone, the horizontal displacement and acceleration of soil layer and strata show obvious difference response. The author thinks that this is the fundamental reason for the slope sliding in the contact zone between soil and rock. The horizontal displacement and PGA magnification coefficient of the slope is obviously larger than that of the slope of the moraine soil, so the horizontal displacement and PGA magnification coefficient of the slope are obviously larger than the slope of the moraine soil. The failure degree of soil-rock structure slope is more controlled by soil type.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P315.9

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