输电线路掏挖基础抗拔极限承载力的可靠度分析

Reliability Analysis on Ultimate Uplift Bearing Capacity of Belled Pier Foundation in Transmission Line Engineering

根据输电线路掏挖基础抗拔极限承载力计算理论,给出了现行DL/T 5219-2005《架空送电线路基础设计技术规定》中"剪切法"系数A1和A2的理论公式,可修正现行设计技术规定中A1和A2的参数取值。根据修正后的系数A1和A2计算了试验掏挖基础抗拔极限承载力的理论值。分析了无量纲随机变量试计比(试验值/理论计算值)的均值、标准差、变异系数和概率分布特征,提出了采用"校准法"对掏挖基础抗拔极限承载力的可靠度进行分析的方法,给出了其在不同安全系数条件下的可靠度指标,并据此量化分析了我国掏挖基础的安全可靠度指标。研究成果可为输电线路掏挖基础抗拔极限承载力计算理论的完善以及现行杆塔基础设计技术规定中"剪切法"抗拔计算系数A1和A2的修正提供依据。

Based on the theory of uplift bearing capacity for belled pier foundations, this paper presented the theoretical formula for the parameters A1 and A2 by shearing method according to the DL/T 5219-2005 technical specifications for foundation designing of overhead transmission lines. The values for parameters A 1 and A 2 were revised. And then, the theoretical values of the tested pier foundations were calculated by using the revised parameters of A1 and A2. According to the field test results, the dimensionless ratio of the tested ultimate uplift load to the theoretically calculated value was introduced to reflect the uncertainty of the uplift bearing capacity for belled pier foundations. The mean, standard deviations, and variability coefficient and probability distribution of the ratio ware analyzed. With the help of the above results, the reliability index of bearing capacities of ultimate uplift bearing capacity was obtained. All these research findings would provide with useful data for the advancing in the theory on overhead transmission fine engineering and for the revising data of parameters A1 and A 2 in the future.