不同渗透性土体的水土压力实验研究

发布时间：2018-03-06 20:30

本文选题：挡墙　切入点：渗透性　出处：《华东交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：在水土压力理论计算方面,专家学者已经进行了广泛的研究,水土分算和水土合算是现如今应用最广泛的计算方法,但这两种方法有不同的适用性,一般认为水土分算方法适用于渗透系数较大的土体,水土合算主要应用于渗透系数较小的土体,而渗透系数处于这两类土体之间的土体究竟是采用水土分算还是水土合算,对于这个问题,专家学者还存在很大的争议,并且对孔隙水压力研究的也相对较少。因此,本文试着从这个角度做些初步的研究工作。本文将南昌市昌北地区的金港粉土作为基本土体,在粉土中掺入不同比例的膨润土和细砂来配置出六种不同渗透系数的土样作为实验土样。将这六种实验土样填入到自制实验槽中,在主动位移和被动位移情况下控制挡墙绕墙底转动,分别量测这六种实验土样的水土压力值和孔隙水压力值。将水土压力压力值与有效应力法水土分算、总效应力法水土分算、总应力法水土合算及徐日庆的水土压力混合算法进行对比分析。同时通过有限元模拟软件ABAQUS对模型实验进行数值模拟,将模拟的结果与实验实测值进行对比,验证实验的准确性。研究的成果主要有:(1)主动位移下的浅层土样在墙顶位移到10mm~11mm时达到主动极限状态,被动位移下的浅层土样则需达到14mm~15mm时进入被动极限状态,而深层土样由于位移小,仍处于非极性破坏状态。(2)原土体中掺入20%、10%和5%细砂的土样适合用水土分算,而原土体及膨润土掺入比为4%、8%和5%细砂的土样适合用水土合算,徐日庆的水土压力混合算法应用在渗透系数较小的土样中较为合适。(3)在主动位移情况下,细砂的掺入比为20%、10%及5%的土样的孔隙水压力相对稳定,而原土体及膨润土的掺入比为4%和8%的土样的孔隙水压力波动比较大,随着墙顶位移的增大,孔隙水压力逐渐趋于静水压力值;在被动位移情况下,掺入20%和10%细砂的土样的孔隙水压力迅速上升到峰值,随着挡墙位移增大,孔隙水压力值缓慢减小到静水压力;掺入5%细砂、4%膨润土和8%膨润土的土样以及原土体,其孔隙水压力值迅速上升到最大,再迅速减少,且出现负超孔隙水压力,随着挡墙位移增大,负超孔隙水压力消散,孔隙水压力逐渐稳定。(4)主动位移时的数值模拟值稍小于实测值,且比实验时较晚进入主动极限状态,而被动位移时的数值模拟值稍大于实测值,比实验时较晚进入被动极限状态。
[Abstract]:In the theoretical calculation of soil and water pressure, experts and scholars have carried out extensive research. Soil and water division calculation and soil and water cost calculation are the most widely used calculation methods nowadays, but these two methods have different applicability. It is generally considered that the soil and water calculation method is suitable for the soil with large permeability coefficient, and the soil and water cost calculation is mainly applied to the soil with small permeability coefficient, and whether the soil mass with the permeability coefficient between these two types of soil is to be calculated by soil and water or soil and water. For this problem, experts and scholars still have a lot of controversy, and the study of pore water pressure is relatively small. This paper tries to do some preliminary research from this angle. In this paper, the Jingang silt in Changbei area of Nanchang City is regarded as the basic soil mass. Six kinds of soil samples with different permeability coefficients were mixed with bentonite and fine sand in silty soil as experimental soil samples. In the case of active displacement and passive displacement, the retaining wall is rotated around the bottom of the wall, and the soil and water pressure values and pore water pressure values of the six experimental soil samples are measured, respectively. The soil and water pressure values of the six experimental soil samples are separated from the effective stress method, and the total effect force method is used to calculate the soil and water. The total stress method and the mixed algorithm of soil and water pressure of Xu Riqing are compared and analyzed. At the same time, the numerical simulation of the model experiment is carried out by the finite element simulation software ABAQUS, and the simulated results are compared with the measured values. To verify the accuracy of the experiment, the main results of the study are: 1) the shallow soil samples with active displacement reach the active limit state when the wall top displacement reaches 10mm / 11mm, and the shallow soil samples under the passive displacement need to reach the passive limit state when they reach 14mm / 15mm. Because of the small displacement, the deep soil samples are still in the nonpolar failure state. (2) the soil samples mixed with 20% and 5% fine sand are suitable for soil and water separation, while the original soil and bentonite samples with the ratio of 4% and 5% fine sand are suitable for water and soil use. In the case of active displacement, the pore water pressure of soil samples with 20% and 5% ratio of fine sand is relatively stable. However, the pore water pressure of the original soil and bentonite samples with ratios of 4% and 8% fluctuates greatly. With the increase of wall top displacement, the pore water pressure tends to hydrostatic pressure, and in the case of passive displacement, the pore water pressure tends to hydrostatic pressure. The pore water pressure of soil samples mixed with 20% and 10% fine sand rapidly increased to the peak. With the increase of retaining wall displacement, the pore water pressure value decreased slowly to hydrostatic pressure, and the soil sample and original soil mass of 5% fine sand with 4% bentonite and 8% bentonite were mixed with 5% fine sand and 8% bentonite, the pore water pressure decreased slowly to hydrostatic pressure with the increase of retaining wall displacement. The pore water pressure rapidly rises to the maximum, then decreases rapidly, and there is negative excess pore water pressure. With the increase of retaining wall displacement, the negative excess pore water pressure dissipates. The numerical simulation value of the active displacement is slightly smaller than the measured value, and it enters the active limit state later than the experimental one, while the numerical simulation value of the passive displacement is a little larger than the measured value. It enters the passive limit state later than the experiment.
【学位授予单位】：华东交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU41

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