水土压力分算与合算的统一算法

UNIFIED METHOD OF SEPARATE AND COMBINED CALCULATION OF WATER AND EARTH PRESSURES

以土中孔隙水特征为基础,假定土体中的黏性土颗粒吸附的结合水会抵消一部分土中孔隙,最终把土的孔隙比、界限含水量、颗粒分析等物理参数引入土水压力计算,提出一个可以采用土层物理指标计算的水压力比率ξ,给出通过土体渗透系数试验测定ξ值的方法,通过该参数可以把有效应力强度指标与总应力强度指标统一在一个强度公式中。同时,给出一个可以统一水土分算和合算的算法,实现水土压力分算和合算结果之间的过渡,为解决水土压力分算和合算结果的跳跃提供一个新思路。根据理论分析,渗透系数–孔隙比实测曲线应该沿e轴正向平移,土体中黏粒成分含量越高,平移量越大,相关文献的试验数据可证实这点;含有黏粒成分的砂性土采用水土分算偏于保守,而孔隙比较大的黏性土采用水土合算偏于不安全;围护结构上的水土压力计算不但与土体分类有关,还与孔隙比直接相关。

Applying combined calculation of water and earth pressures for clay leads to a result which is more close to the field measurement value, however, obviously violates the principle of effective stress. Based on characteristics of the pore water in soil, it is assumed that the bound water absorbed by the clay particles in the soil offsets part of soil pore, and finally physical parameters such as void ratio, boundary water content, particle analysis, etc. are introduced to calculation of water and earth pressures on retaining structures to propose a coefficient ~ which can be calculated through physical parameters of soil and to provide the method of measuring the value of ~ through permeability tests. With the coefficient ~, the effective stress intensity index and total stress intensity index are integrated in one strength formula. A new calculation method to unify the separate calculation and combined calculation of water and earth pressures is proposed to carry out the transition between results of the two conventional calculation methods and provide a new idea for solving the jump problem between the two results. According to the theory analysis of this paper, the measured permeability coefficient-void ratio curve will have a translational move in a forward direction along e-axis. The more clay particles that soil contains will have the larger translation, which has been verified by experimental data of related literatures. Separate calculation of water and earth pressures is too conventional for sand soil containing clay particles while combined calculation of water and earth pressures for clay with high void ratio can＇t guarantee the safety. Water and earth pressures on retaining structure are related not only to the soil categories, but also the void ratio,