基于柱孔扩张理论的沉井刃脚极限土阻力分析

Analysis of Ultimate Soil Resistance Beneath Cutting Curb Based on Cylindrical Cavity Expansion Theory

为解决目前刃脚极限土阻力计算方法所存在的不足,基于考虑剪胀效应的柱孔扩张理论,提出了刃脚极限土阻力的理论解答.首先考虑刃脚基础单侧方向破坏的特点,将两个刃脚对称拼接成一个整体基础进行计算;其次利用柱孔扩张理论,通过分析刃脚底部土体在竖直方向的受力平衡求得刃脚极限土阻力;最后利用离心模型试验与现场监测对该计算方法进行了对比验证.研究结果表明:与离心模型试验结果相比,当沉井下沉深度为36 m时,本文方法计算刃脚土阻力误差为6.6%,与现场实测结果相比,当沉井下沉深度为5 m时,本文方法计算刃脚土阻力误差为1.36%,当沉井下沉深度为10 m时,本文方法计算刃脚土阻力误差为19.5%,当沉井下沉深度为15 m时,本文方法计算刃脚土阻力误差为9.70%.计算值与离心模型试验值、现场实测值均吻合较好.本研究可为刃脚极限土阻力计算问题提供一个新思路.

To overcome the shortcomings of the conventional calculation method of the ultimate soil resistance beneath the cutting curb,a theoretical solution for the ultimate soil resistance beneath the cutting curb is proposed based on the theory of cylindrical cavity expansion considering dilation effects.First,characteristics of the unilateral failure of cutting curb foundation are considered and two cutting curbs are symmetrically spliced into an integral foundation for calculation.Then,the ultimate soil resistance beneath the cutting curb is obtained by using the theory of cylindrical cavity expansion and analyzing the vertical force balance of the soil at the bottom of the cutting curb.Finally,centrifugal model test and field monitoring are used to verify the calculation method.Results show that compared with the results of centrifugal model test,the error of the ultimate soil resistance beneath the cutting curb calculated by this method is 6.6%when the sinking depth of caisson is 36 m.Compared with the results of field monitoring,the error of the ultimate soil resistance beneath the cutting curb calculated by this method is 1.36%,19.5%,and 9.70%when the sinking depth of caisson is 5 m,10 m,and 15 m,respectively.The calculated values agree well with the centrifuge model test values and field measured values.This study can provide a new idea for calculating the ultimate soil resistance beneath the cutting curb.