粉喷桩处置软土地基的桩土扰动问题及室内模拟试验研究

对粉喷桩施工过程中桩土界面处应力及桩周土应力状态进行了深入的理论分析,并进行了有限元数值模拟,通过室内试验结果分析,探讨了粉喷桩处置软土的施工扰动问题,得出了粉喷桩施工中的土体扰动的一些基本规律,即扰动度与土体的固结屈服应力之间呈负幂指数关系,土体屈服应力随扰动度增加而急剧减小。剪应变qε随空气压力的增大而增大,随桩距比增大呈指数规律减小。粉喷桩施工过程中对土体的扰动比较大的范围为3倍桩半径范围,即正常在0.8~1.0 m之间。

Pile-soil Disturbance in Soft-soil Foundation Treatment Using DJM and Its Indoor Simulation Test

The pile-soil interface stress and the pile surrounding soil stress condition in the construction process were analyzed with FEM method.Through analyzing the indoor test results,the basic rules of soft-soil disturbance in dry jet mixing(DJM) pile construction were obtained.The results show that(1) there is the negative exponent relation between the disturbance degree and yield consolidation stress of the soil,i.e.,the yield consolidation stress reduces sharply with increasing of the disturbance degree;(2) shear strain increases with the increasing of the air pressure and reduces with the increasing of the pile spacing ratio;(3) in the construction process,the relatively large range of soil disturbance is three times the pile radius,that is normally in between 0.8 m and 1.0 m.