基坑倾斜桩支护稳定特性及分析方法研究

工程实践已证明基坑倾斜桩无支撑支护具有良好的变形和稳定控制性能。然而,倾斜支护桩稳定特性和分析方法尚缺乏研究。通过数值模拟研究了倾斜支护桩在基坑开挖过程中变形到破坏的全过程,分析了倾斜角、插入比以及土体强度对安全系数的影响。推导了基坑倾斜桩支护的抗倾覆与整体稳定安全系数计算方法,并与离心机试验结果进行了对比分析。结果表明:(1)针对常规倾斜角度(≤20°),倾斜支护桩临界破坏模式为倾覆失稳;(2)倾斜桩支护的稳定性能随倾斜角,插入比和土体强度的增大而显著增强;(3)倾斜桩的重度影响倾覆破坏时旋转点位置,桩身重度及旋转点位置导致抗倾覆力矩增大,使之具备良好的抗倾覆稳定性。

Stability characteristics and analysis method for inclined retaining walls in excavations

The inclined strut-free retaining walls have the advantages in deformation and stability control.However,the insight into the stability theory of inclined retaining walls is limited.The whole process of deformation and failure of the inclined retaining walls during excavation is studied through numerical simulation,and the influences of parameters,including the inclined angle,the embedded ratio and the shear strength of the soil,on the factor of safety are analyzed.The method for calculating the anti-overturning stability and overall stability of the inclined retaining walls is derived,and the validation is carried out by comparing with the centrifuge tests.The results show that:(1) For the conventional inclination angle(≤20°),the inclined retaining walls experience overturning failure.(2) The capacity of the overturning resistance and deforming control of the inclined retaining walls are enhanced with the increasing inclination angle,buried depth of piles and shear strength of the soil.(3) The wall weight influences the pivot location,and the weight and the pivot can increase the anti-overturning moment of the retaining walls.Hence,the inclined retaining walls have a great anti-overturning capacity.