时间平方根法评价隔离墙t50及固结系数

Evaluation of the t50 Value and Coefficient of Consolidation of Cutoff Wall Based on Square Root of Time Method

在孔压静力触探测试过程中,常出现孔隙水压力在消散过程中先增加再减小的现象,这种现象被称为非标准消散类型。而在非标准消散类型中,常采用传统标准消散类型分析方法,通过初始孔压得出t值及固结系数,这种方法因忽略孔压上升段故而存在一定的误差。基于此,对初始孔压进行修正至关重要。采用时间平方根法对初始孔压进行修正,继而评价t值及固结系数。同时,对于试验现场消散时间小于t的情况,通过时间平方根法预测t值,进而评价此处的固结系数,从而节约现场测试时间。最后,将时间平方根法与时间对数法及修正t法进行对比。研究表明,时间平方根法与时间对数法得出的固结系数比较接近,修正t法得出的固结系数较前两种方法更大。

In the process of piezocone penetration test,pore pressure often increases first and then decreases during the dissipation process.This phenomenon is called non-standard dissipation type.However,in the non-standard dissipation type,the traditional standard dissipation type analysis method is often adopted.By using the initial pore pressure,the tvalue and coefficient of consolidation are obtained.This method has some errors because it ignores the rising section of pore water pressure.Based on this,it is very important to correct the initial pore pressure.the initial pore pressure is corrected by the square root of time method,and then the tvalue and the coefficient of consolidation are evaluated.At the same time,for the case where the dissipation time at the test site is less than t,the tvalue is predicted by the square root of time method,and the coefficient of consolidation is evaluated so as to save on-site test time.Finally,this paper compares the square root of time method with the logarithmic of time method and the modified tmethod.The research shows that the coefficient of consolidation obtained by time square root method is close to that obtained by time logarithm method,and the coefficient of consolidation obtained by the modified tmethod is larger than that obtained by the previous two methods.