随机变量对土钉墙抗外部稳定可靠性的影响分析

Analysis on the Random Variables’Influence on Outside Stability of Soil Nailed Wall

基坑支护结构的稳定性问题具有较强的随机不确定性,传统的安全系数法是一种确值设计法;由于未考虑参数的变异性而具有很大的局限性。结构可靠度理论以承认结构有失稳的可能性为前提,并以失稳概率度量结构的可靠性,相比较而言能够更为科学、客观地反映工程的随机性特质。通过对土钉墙抗整体滑移和倾覆稳定性问题的研究,建立了可靠度分析相应的功能函数;并结合一工程实例采用JC法计算了相应的可靠指标。针对其抗整体滑移这一控制性失稳模式,研究了随机变量概率分布类型、随机变量的均值、变异系数等对可靠指标的影响,总结了相关规律和结论,可以为类似基坑支护工程实践提供一定的理论参考依据。

The stability of bracing structure for foundation pit has strong random uncertainties,the traditional safety coefficient method is a kind of certain design model which has intense limitation since the coefficients’variability are not involved in.The structural reliability theory is on the premise of the structure has unstable possibility and using the failure probability to measure the reliablility of the structure,it could reflect the random characteristics of engineering scientifically and objectively.According to the study on the anti-slippage and anti-overturn stability of the soil nailed wall,there performance functions are established,and in the light of an engineering example,there reliability indexes are calculated based on JC method.And furthermore,the discussion aimed at the antislippage stability which is the more important stable model of the example is carried out to ascertain how the random variables’probability distribution,the variables’means,the coefficients of variation,etc.influence on the reliability index,and therefore,some related regularities and results are summarized which could provide some theoretical references for similar engineering practice.