南水北调深挖方膨胀土渠坡抗滑桩作用机理分析

发布时间：2018-09-03 20:26

【摘要】：本文针对南水北调中线工程河南南阳段渠坡开挖施工中出现膨胀土滑坡的问题,利用有限元方法对深挖方膨胀土渠坡滑塌机理及采用抗滑桩后的抗滑机理进行了数值模拟和分析。主要考虑了膨胀土在干湿循环作用下土体软化和土体膨胀两方面的影响因素,分析了干湿循环对渠坡滑坡的影响和对抗滑措施作用效果的影响,从边坡土体位移变化、塑性应变,以及抗滑桩的应力、应变以及桩土之间的土拱效应几个方面进行了分析,探讨了在于湿循环作用下抗滑桩的最佳施工时机以及抗滑措施。具体内容如下：首先,基于室内试验获得了模型分析的桩、土基本参数,主要是土水特征曲线、强度参数、膨胀力参数和弹性模量以及泊阿松比；接着,结合河南南阳自然气候条件,在降雨渗流分析理论的基础上,对南阳二标渠坡进行了干湿循环区域的仿真计算,分析了干湿循环作用下,不同时期干湿循环影响区域的范围,并对影响区域进行了分层,结合试验和已有文献,采用类比方法,确定了干湿循环影响区域不同层的土体强度参数和影响区域土体吸水产生的膨胀力大小；然后,以非饱和土抗剪强度理论和强度折减法为基础,对南阳二标渠坡进行三维渠坡模型的建立,从应力、应变、土体位移等方面分析了膨胀土渠坡发生深层滑坡的机理,表明了沿软弱结构面易发生较平缓的深层滑坡,并且通过研究不同时期干湿循环作用下的渠坡,得到了抗滑桩施工的最佳时机。最后,将干湿循环影响下土体软化、土体膨胀与具有抗滑桩膨胀土渠坡结合起来,从土体位移、桩身位移、桩身受力以及桩土之间的土拱效应几个方面对渠坡进行抗滑作用机理分析,得出抗滑桩作用于深层渠坡的优缺点,提出渠坡深层抗滑的措施,但同时也说明了抗滑桩不能进行浅层抗滑,要对膨胀土进行浅层抗滑需要其它方法,如：浅表层土质改良或者进行防水措施。
[Abstract]:Aiming at the problem of expansive soil landslide in excavation construction of canal slope in Nanyang section of Henan Province in the middle route of South-to-North Water transfer Project, The mechanism of sloughing of expansive soil channel slope in deep excavation and the anti-slide mechanism of anti-slide pile are simulated and analyzed by finite element method (FEM). This paper mainly considers the influence factors of soil softening and soil swelling under dry and wet circulation, analyzes the influence of dry and wet circulation on channel slope landslide and the effect of anti-slide measures, and changes the displacement of slope soil. Plastic strain, stress and strain of anti-slide pile and soil arch effect between pile and soil are analyzed, and the optimum construction time and anti-slide measure of anti-slide pile under wet circulation are discussed. The main contents are as follows: firstly, the basic parameters of soil, such as soil water characteristic curve, strength parameter, expansion force parameter and elastic modulus and Poisson's ratio, are obtained based on the indoor test. Combined with the natural climate conditions in Nanyang, Henan Province, on the basis of the theory of rainfall seepage analysis, the dry and wet circulation region of Nanyang second standard canal slope was simulated and calculated, and the range of dry and wet circulation affected areas in different periods was analyzed. The soil strength parameters of different layers in the affected area and the swelling force of the soil mass in the region affected by dry and wet circulation are determined by analogy method, combined with the experiment and the existing literature. Based on the shear strength theory of unsaturated soil and the strength reduction method, the three-dimensional model of channel slope in Nanyang Erbiao channel is established. The mechanism of deep landslide in expansive soil canal slope is analyzed from the aspects of stress, strain and soil displacement. The results show that the deep landslide is easy to occur along the weak structural plane, and the optimum time for the construction of anti-slide pile is obtained by studying the channel slope under the action of dry and wet circulation in different periods. Finally, soil is softened under the influence of dry and wet circulation, and soil swelling is combined with expansive soil channel slope with anti-slide pile. Based on the analysis of the anti-slide mechanism of the pile and the soil arch effect between the piles and soil, the advantages and disadvantages of the anti-slide pile acting on the deep channel slope are obtained, and the measures for the deep slide resistance of the canal slope are put forward. But at the same time, it also shows that anti-slide pile can not be used in shallow layer, and other methods are needed to resist sliding in shallow layer of expansive soil, such as improving the quality of shallow surface soil or waterproofing measures.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV68;TV553

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