典型堆积层滑坡抗滑桩土拱形成机理研究

发布时间：2018-11-26 20:21

【摘要】：堆积层滑坡是滑坡的一种基本类型,坡体组份多为碎石土(粗粒土),抗滑桩在此类型滑坡治理工程中得到广泛应用；抗滑桩设计的主要内容之一是确定抗滑桩的排列间距,合理的间距布置可以形成土拱,并能最大限度的发挥抗滑桩之间土体的自承载能力。目前关于抗滑桩中土拱的形成机理尚有待进一步研究。因此,本文针对性的开展了抗滑桩中土拱形成机理的理论和数值研究,分析抗滑桩的桩-土相互作用机理、荷载传递规律等问题,为抗滑桩的设计与间距的确定提供技术支撑与参考。论文从分析堆积层滑坡的基本特征入手,选取三峡库区典型堆积层滑坡——马家沟滑坡为研究对象,通过室内试验获取滑体粗粒土的基本物理力学参数和应力应变关系,指导修正PFC3D进行数值三轴试验,得到滑体粗粒土的细观力学参数,运用到概化出的马家沟滑坡三维桩-土作用数值计算模型,并结合力学理论的推导,全面系统的研究了典型堆积层滑坡抗滑桩土拱的形成机理及过程。本文的主要研究内容如下所述： (1)总结三峡库区堆积层滑坡的基本特征和介绍库区典型堆积层滑坡——马家沟滑坡的工程地质特征。 (2)从理论方面总结阐述土拱效应,研究抗滑桩中土拱效应的实质和土拱传递滑坡推力的方式；根据抗滑桩的受力特点,利用力学理论建立抗滑桩承受矩形和三角形滑坡推力作用下桩后土拱效应的平面力学分析模型,推导桩后土体应力场的分布函数,对土拱应力的等值线分布形态进行探讨。 (3)研究马家沟滑坡滑体粗粒土的物理力学性质,运用PFC3D进行粗粒土的数值三轴剪切试验,获取粗粒土细观力学参数和分析剪切位移场形成发展规律。 (4)构建颗粒流三维桩-土作用模型,从细观力学角度分析土拱的形成和发展变化过程,研究土拱的力学传递机制,总结土拱形成内部应力变化规律,探索土拱的形成机理。通过研究上述内容,本文取得了以下创新成果： (1)改进了矩形和三角形滑坡推力作用下抗滑桩后土体应力场的平面分布函数,对比分析了土拱应力的等值线分布形态。 (2)研究了库区堆积层滑坡滑体粗粒土的细观力学性质,给出了粗粒土数值三轴剪切试验中剪切位移场的变化规律。 (3)研究了三维桩-土作用的细观力学过程,分析了桩间土拱形成内部应力变化规律,总结出桩间土拱分布形态随加载过程和深度改变的变化规律。
[Abstract]:The accumulation layer landslide is a basic type of landslide, the slope body composition is mostly gravel soil (coarse grained soil), the anti-slide pile is widely used in this type landslide treatment project. One of the main contents of anti-slide pile design is to determine the arrangement distance of anti-slide pile. Reasonable spacing arrangement can form soil arch and maximize the self-bearing capacity of soil between anti-slide piles. At present, the formation mechanism of soil arch in anti-slide pile remains to be further studied. Therefore, this paper has carried out the theoretical and numerical research on the formation mechanism of soil arch in anti-slide pile, analyzed the pile-soil interaction mechanism of anti-slide pile, the law of load transfer and so on. It provides technical support and reference for the design of anti-slide pile and the determination of spacing. Based on the analysis of the basic characteristics of the accumulation layer landslide, Majiagou landslide, a typical landslide in the three Gorges Reservoir area, is selected as the research object, and the basic physical and mechanical parameters and stress-strain relationship of the slider coarse grained soil are obtained through laboratory tests. The numerical triaxial test of modified PFC3D is directed to obtain the meso-mechanical parameters of coarse-grained soil of sliding body. The numerical model of three-dimensional pile-soil interaction of Majiagou landslide is applied to the generalized numerical calculation model of pile-soil interaction in Majiagou landslide, and combined with the derivation of mechanical theory. The formation mechanism and process of anti-slide pile-soil arch of typical accumulation layer landslide are studied in this paper. The main contents of this paper are as follows: (1) summarize the basic characteristics of the landslide in the three Gorges reservoir area and introduce the engineering geological characteristics of the typical landslide in the reservoir area, the Majiagou landslide. (2) summarize and expound the soil arch effect from the theoretical aspect, study the essence of soil arch effect in anti-slide pile and the way that soil arch transfers landslide thrust; According to the stress characteristics of anti-slide pile, the plane mechanics analysis model of soil arch effect of anti-slide pile under the action of rectangular and triangular landslide thrust is established by using mechanics theory, and the distribution function of soil stress field behind pile is deduced. The contour distribution of soil arch stress is discussed. (3) the physical and mechanical properties of coarse grained soil in Majiagou landslide are studied. The numerical triaxial shear test of coarse grained soil is carried out by using PFC3D, and the meso-mechanical parameters of coarse grained soil and the rules of formation and development of shear displacement field are obtained. (4) the three-dimensional pile-soil interaction model of particle flow is constructed, the formation and development process of soil arch is analyzed from the viewpoint of meso-mechanics, the mechanical transfer mechanism of soil arch is studied, the law of internal stress change of soil arch formation is summarized, and the formation mechanism of soil arch is explored. By studying the above contents, this paper has obtained the following innovative achievements: (1) the plane distribution function of soil stress field after sliding pile under the action of rectangular and triangular landslide thrust is improved. The isoline distribution of soil arch stress is compared and analyzed. (2) the mesomechanical properties of coarse grained soil of landslide in reservoir area are studied, and the variation law of shear displacement field in numerical triaxial shear test of coarse grained soil is given. (3) the meso-mechanical process of three-dimensional pile-soil interaction is studied, and the variation law of internal stress in the formation of soil arch between piles is analyzed, and the variation law of the distribution of soil arch between piles with the change of loading process and depth is summarized.
【学位授予单位】：中国地质大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：P642.22;TU473.1

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