黏性土的土压力计算理论研究

发布时间：2018-03-05 13:04

本文选题：水土分算与合算　切入点：水土共同作用系数　出处：《浙江大学》2013年硕士论文　论文类型：学位论文

【摘要】：近年来,伴随着城市化进程的不断推进,地下空间得到了广泛地开发利用,同时也产生了许多工程问题,需要在基坑设计理论方面进行进一步地完善。作用在基坑围护结构上的荷载的计算问题一直是进行基坑设计最为核心的课题,这就涉及到土力学的一个基本内容：土压力计算理论。本文在总结前人研究成果的基础上,主要对黏性土基坑水土压力计算、非极限主动土压力计算以及开挖卸载引起的超固结土土压力计算三个基本问题进行了理论研究,并通过已有的试验结果和算例进行了验证。现有的基坑水土分算与合算方法只能计算极端情况下的水土压力,适用性不强。本文基于黏性土的微观结构,根据黏性土结合水要占据一定的孔隙体积从而影响孔隙水压力的传递这一事实,提出了土水共同作用系数ξ的计算方法,统一了黏性土的两套强度指标,推导了水土压力的统一计算方法。算例分析表明,本文的统一算法能够计算从无黏性土到黏性土的所有水土压力,具有普遍适用性。黏性土的非极限主动土压力无论是试验还是理论研究成果都很少。本文从黏性土的应力莫尔圆出发,推导了黏性土强度指标内摩擦角φ、黏聚力c随墙体位移变化的计算公式。采用水平条分法得到了非极限主动土压力,本文理论计算结果与已有的模型实验结果基本吻合。基坑开挖时,坑底墙前土体的土压力是一个由卸载引起的超固结土的土压力问题,涉及到土体的有效上覆压力与超固结土强度指标的取值等问题。本文根据土体开挖卸载的受力特点,提出了超固结土的有效上覆压力和强度指标的计算公式,修正了朗肯被动土压力公式用于计算墙前被动土压力,与传统计算方法的计算结果进行对比表明,本文方法能够改正传统计算方法计算结果偏小的问题。
[Abstract]:In recent years, with the continuous progress of urbanization, underground space has been widely developed and utilized, and many engineering problems have emerged. The theory of foundation pit design needs to be further improved. The calculation of load acting on the retaining structure of foundation pit has always been the core of foundation pit design. This involves a basic content of soil mechanics: soil pressure calculation theory. Based on the previous research results, this paper mainly deals with the calculation of soil and water pressure of clay soil foundation pit. Three basic problems, namely, the calculation of non-limit active earth pressure and the calculation of overconsolidated earth pressure caused by excavation and unloading, are theoretically studied and verified by existing experimental results and examples. The existing methods for calculating soil and water in foundation pit can only calculate soil and water pressure in extreme cases, and are not applicable. This paper is based on the microstructure of clay soil. According to the fact that clay soil combined with water must occupy a certain pore volume and affect the transfer of pore water pressure, the calculation method of soil-water interaction coefficient 尉 is put forward, and two sets of strength indexes of clay soil are unified. The unified calculation method of soil and water pressure is deduced. The example analysis shows that the unified algorithm can calculate all soil and water pressure from non-clay soil to clay soil, and it has universal applicability. There are few experimental and theoretical results on the non-limiting active earth pressure of clay soil. In this paper, the stress moire circle of clay soil is studied. The formulas of internal friction angle 蠁 and cohesive force c of clay soil strength index with wall displacement are derived. The non-limiting active earth pressure is obtained by horizontal strip method. The theoretical calculation results are in good agreement with the experimental results of existing models. During excavation of foundation pit, the earth pressure of the soil in front of the pit bottom wall is an overconsolidated soil pressure problem caused by unloading. The effective overburden pressure of soil and the value of strength index of overconsolidated soil are concerned. According to the stress characteristics of excavation and unloading of soil, the formula for calculating effective overburden pressure and strength index of overconsolidated soil is put forward in this paper. The formula of Rankine's passive earth pressure is modified to calculate the passive earth pressure in front of the wall. The comparison with the traditional calculation method shows that this method can correct the problem that the calculation result of the traditional method is too small.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU432

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