饱和黏性地层中基坑坑底抗隆起稳定验算方法

针对饱和黏性土地层中基坑坑底抗隆起稳定性验算，首先建议其强度指标取原状土样在有效自重应力下预固结的不固结不排水抗剪强度cu，随后考虑该不排水抗剪强度随深度近似线性增大的特点，给出相应地基承载力的计算公式。进而在作者此前所提出的坑底抗隆起稳定性验算方法基础上，给出饱和黏性土地层中深基坑坑底抗隆起稳定安全系数的计算方法，包括挡土构件嵌深较小情况下按地基承载力的验算方法，嵌深较大情况下按圆弧滑移面的验算方法和识别过大嵌深的临界嵌深计算公式，并通过与精细数值方法计算结果的对比，对所提出方法及公式的正确性和精度进行了检验。文中还给出两个工程实例，展示了实际分层地基，特别是既有黏性土也有无黏性土层时按所提出方法的坑底抗隆起验算。

Checking method for basal heave stability of deep excavation in saturated cohesive soil

 For checking the basal heave stability of deep excavation in saturated cohesive soils, it is firstly clarified that the undrained strength shall be employed. Then an evaluation method for the ground bearing capacity is proposed in consideration of the approximately linear increase of the undrained strength with depth. Thereafter, the checking method is given for the basal heave stability of deep excavation in saturated cohesive soils by referring to the authors’previous studies. The proposed method is composed of the safety factor calculation in terms of ground bearing capacity for relatively small embedded depth of the supporting structure, the stability checking by assuming circular slip surface for relatively large embedded depth and the formula for determining the critical embedded depth beyond which the safety factor remains almost unchanged. By comparing with the refined numerical calculations, the proposed method was validated. Through the analyses of two practical projects involving layered ground of cohesive soil and cohesionless soil, the practical applicability of the proposed method was demonstrated.