对基坑抗隆起稳定安全系数的改进

基坑的平面形状、尺寸以及围护结构的入土深度都会影响基坑的抗隆起稳定性，但现行规范推荐的抗隆起稳定安全系数算法均不能反映这些因素的综合影响。为解决这一问题，区分不同情况，对基坑底隆起破坏可能的模式做了必要的分类，分别给出了不同破坏模式情况下抗隆起稳定安全系数的计算方法。基于此方法，基坑围护结构的强度、刚度和入土深度都会影响基坑的抗隆起稳定性。计算分析表明，无论是对于排水情况还是不排水情况，狭窄基坑都具有更好的稳定性，而围护结构的入土深度可提高基坑的稳定性。改造后的基坑安全系数使传统算法可以考虑更多因素，为狭窄基坑缩小围护结构入土深度提供了一个理论手段。

Improvement on safety coefficient of heave-resistant stability of excavations

The plane shape, size of the excavation and embedment depth of the retaining wall all affect the heave-resistant stability of excavations. However, the influence of above factors can’t be comprehensively expressed by the calculation methods of safety coefficient of heave-resistant stability recommended from existing standards and codes. In order to solve this problem and differentiate the situations, the possible failure modes of basal heave are classified; and thereby the corresponding formulas calculating the safety coefficient of heave-resistant stability under different failure modes are given. Based on this method, the heave-resistant stability of excavations will be influenced by the strength, stiffness and embedment depth of the retaining wall. The calculation analyses indicate that, for both the drained and undrained situation, the narrow excavations are more stable than wide ones, and that the stability can be improved by adjusting the embedment depth of the retaining wall. The improved excavation safety factor, can take more factors into account, which provides a theoretical method to reduce the embedded depths of the retaining wall of narrow excavations.