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针对上海软土深基坑开挖降水过程中所涉及的③层淤泥质粉质黏土、④层淤泥质黏土、⑤-1层粉质黏土、⑤-2层黏质粉土,通过二阶段固结模拟和K0试验,研究了各层土在不同降水深度条件下土侧压力系数的变化特性.试验结果显示:降水前后,黏性土侧压力系数值相对粉性土为大;各层土侧压力系数值均随水位降深的增加而减小,每米水位降深,⑤-1层、⑤-2层、③层、④层土的侧压力系数值分别下降3.1%,2.5%,2.3%,1.3%左右;随着降水深度的增大,降水对侧压力系数的影响在逐渐减小,并最终趋于稳定.最后,基于回归分析理论得到侧压力系数简易计算公式,为上海地区深基坑降水后土侧压力系数的确定提供参考.
According to the three layers of muddy silty clay, ④ silt clay, ⑤-1 silty clay and ⑤-2 clay silt involved in the excavation and dewatering of Shanghai soft soil deep foundation pit, Knot test and K0 test, the variation characteristics of soil pressure coefficient at different depths of soil under different precipitation depths were studied.The results show that the lateral pressure coefficient of clay before and after precipitation is larger than that of earthy soil, The values of pressure coefficient decreased with the increase of water level and the water level of each meter decreased. The lateral pressure coefficient of ⑤-1, ⑤-2, ③ and ④ soil decreased by 3.1%, 2.5% and 2.3% respectively % And 1.3% respectively.With the increase of precipitation, the influence of precipitation on lateral pressure coefficient decreases gradually and finally stabilizes.Finally, based on the regression analysis theory, a simple formula of lateral pressure coefficient is obtained, The reference of soil pressure coefficient after foundation pit dewatering is provided.