基于土体流变特性的库岸堆积体斜坡失稳机理研究

发布时间：2018-06-25 10:25

本文选题：土流变 + 岸坡失稳　；参考：《重庆交通大学》2017年硕士论文

【摘要】：近年来,土体的流变特性越来越受到岩土工程界的重视,这使得考虑土体流变特性的斜坡破坏失稳机理成为目前的研究热点和重点。对于位于水库或者沿河地区的斜坡来说,水位波动是造成斜坡失稳的最主要影响因素。本论文以自然状态下的库岸堆积体土坡为研究对象,致力于构建能够反映岸土坡失稳机理的岸坡安全系数-库水波动-岸坡土流变强度联动协调机制,论文主要的研究工作及研究成果包括以下几方面:(1)系统性地引入土流变学基本理论、对比土流变元件模型特点和组合原理、掌握流变参数的识别方法,分析得知西元正夫元件模型和Burgers元件模型在模拟斜坡土流变方面具有优良性。(2)利用西元正夫元件模型,并结合滑坡的流变控制理论,论文在考虑了斜坡失稳的强度准则以外,建立了斜坡失稳的位移准则,并通过该准则和利用模型,建立了斜坡安全系数与时间的函数关系式。论文采用了Patton准则和西元正夫流变模型对斜坡滑带土的流变参数进行了识别。论文收集了三峡库区某土质斜坡流变参数,建立了滑带土抗剪强度和时间的关系曲线。(3)论文进行了三峡库区大型土质滑坡滑带土室内剪切流变实验,发现了不同荷载等级下滑带土的流变特性规律和长期强度规律。并根据试验数据,利用Burgers流变模型进行了流变参数的辨识,得到了岸坡滑带土的流变方程,论证了土流变与斜坡失稳的关系,即在不同的载荷条件下,斜坡土体呈现不同流变强度,斜坡失稳最易发生在土体加速流变阶段。(4)为了在土流变-岸坡失稳关系中充分考虑库水的影响,论文对非饱和土力学相关公式进行了计算和推导,并通过滤纸实测方法建立了基质吸力与土体含水率的关系曲线。该曲线表明:随着斜坡非饱和土体随含水量的增加,其基质吸力值减小;土的基质吸力减小,斜坡滑带土的抗剪强度降低。(5)论文利用FLac3D有限差分数值模拟软件建立了岸坡的计算模型,求得了库水波动条件下的岸坡安全系数与库水位的对应关系。通过运用斜坡演化的非线性动力学模型,找到了岸坡土流变强度与库水位值二者之间的对应关系,并且建立了岸坡土流变强度的评判标准。成功构建了能够反映库岸堆积体土坡失稳机理的岸坡安全系数-库水波动-岸坡土流变强度三者的联动协调机制。该机制表明:库水位急剧下降,岸坡土介质流变强度增大,岸坡的安全性降低。(6)最后,论文通过工程实例分析,论证了文中所提出的岸坡安全系数-库水波动-岸坡土流变强度的联动协调机制的合理性。
[Abstract]:In recent years, the rheological properties of soil have been paid more and more attention by the geotechnical engineering community. This makes the failure mechanism of slope failure to consider the rheological properties of soil. The water level fluctuation is the most important factor for slope instability in the reservoir or the river area. The reservoir slope of the bank bank in the state is the research object, which is devoted to constructing the coordination mechanism of the bank slope safety factor - the reservoir water fluctuation - the rheological strength of the bank slope, which can reflect the failure mechanism of the bank slope. The main research work and the research results of the paper include the following aspects: (1) systematically introducing the basic theory of soil rheology and comparing the soil rheology element The characteristics and combination principle of the model and the identification method of the rheological parameters are mastered. It is found that the Nishimoto Masao element model and the Burgers element model have good characteristics in the simulation of slope soil rheology. (2) using the Nishimoto Masao element model and combining the rheological control theory of the landslide, the paper considers that the strength criterion of slope instability is considered. In this paper, the relationship between the slope safety coefficient and the time is established through this criterion and the use model. The paper uses the Patton criterion and the Nishimoto Masao rheology model to identify the rheological parameters of the slope slide soil. The paper has collected the rheological parameters of a soil slope in the Three Gorges Reservoir Area and established the resistance of the slide soil. The relation curve of shear strength and time. (3) the paper carried out the laboratory shear rheology experiment of the large soil landslide belt soil in the Three Gorges Reservoir area, found the law of rheological characteristics and long-term strength of the soil with different load grades. According to the test data, the rheological parameters were identified by the Burgers rheology model, and the slope sliding zone was obtained. The rheology equation of soil demonstrates the relationship between soil rheology and slope instability, that is, under different load conditions, the slope soil presents different rheological strength and slope instability occurs most easily in the soil accelerated rheological phase. (4) in order to fully consider the influence of reservoir water in the relationship of soil rheological and bank slope instability, the paper carries out the relevant formulas of unsaturated soil mechanics. The relation curve of matrix suction and soil moisture content is established by the method of filter paper measurement. The curve shows that with the increase of water content, the suction value of the unsaturated soil decreases with the increase of water content; the matrix suction of soil decreases and the shear strength of slope slide soil decreases. (5) the finite difference numerical simulation of FLac3D is used in the paper. The software has established the calculation model of the bank slope, and obtained the corresponding relationship between the bank slope safety coefficient and the reservoir water level under the condition of the reservoir water fluctuation. By using the nonlinear dynamic model of the slope evolution, the corresponding relationship between the rheological strength of the bank slope soil and the value of the reservoir water level is found, and the evaluation standard of the rheological strength of the bank slope soil is established. The linkage coordination mechanism which can reflect the slope safety factor of bank slope instability mechanism, which can reflect the slope stability of bank slope stability, has been constructed. The mechanism shows that the water level of the bank falls sharply, the rheological strength of the bank slope is increased and the safety of the bank slope is reduced. (6) finally, the paper has demonstrated the proposed method in the paper through an example of the project. The safety coefficient of bank slope - the fluctuation of reservoir water - the rationality of the coordination mechanism of rheological strength of bank slope soil.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV223

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