随时间任意变化荷载下砂井地基固结分析

Consolidation analysis with vertical drains and general time-dependent loading

对随时间任意变化的荷载作用下砂井地基固结问题进行研究。首先推导考虑涂抹效应、井阻作用、土体内径竖向组合渗流、变荷载以及涂抹区水平渗透系数线性连续变化等因素的解析解;然后,将上部荷载进行傅里叶变换转化为三角级数的形式,即将复杂荷载分解为很多简单的正余弦函数之和,通过简单荷载作用下响应的叠加得到原复杂荷载作用下的响应,由此得到一种便于工程应用的简单方法;编制计算程序,与传统解析解进行对比;最后,分析几种荷载模式下砂井地基的固结性状,包括多级线性加载、三角形循环荷载、矩形循环荷载等一般模式,并通过用多段直线段逼近曲线的方法,分析抛物线形循环荷载作用下地基的固结特性。研究结果表明:本文方法合理,具有广泛的适用性。

The consolidation behavior of soils with vertical drains subjected to a general time-dependent loading was studied.Firstly,an analytical solution was obtained accounting for the effects of soil smear,drain hydraulic resistance,coupled flows in the radial and vertical directions within the surrounding soil,time-dependent loading and the linear distribution of the horizontal permeability of soils in the disturbed soils zone.Then,the time-dependent loading was transferred to trigonometric series by the technique of Fourier Transform.By this method,the complex loading was transformed into the sum of a series of sine and cosine function.Then the response of the complex loading was obtained by superimposing the responses of these relatively simple ones.A simple-to-use method was proposed according to this method.Consequently,a calculation computer program was developed and the comparison with a theoretical method was made.Finally,the consolidation behavior of sand drains foundation under several conventional types of time-dependent loading was investigated,including multi-ramp loading,triangular cyclic loading and trapezium cyclic loading.Moreover,the consolidation behavior of sand drains foundation under parabolic cyclic loading was investigated by means of piecewise-linear approximation method.The results indicate that the proposed method is accurate and reasonable.