基于可靠度分析的锚杆抗拔安全系数取值标准研究

Criteria for determining factor of safety of anchor against pull-out by using reliability analysis

现行规范中关于锚杆抗拔安全设计标准,通常是从锚杆杆体的抗拉强度、注浆体与杆体的黏结强度以及注浆体与周围岩土体的黏结强度这3方面来定义抗拔安全系数,并建议采用统一的取值标准。实际上由于力学机理、材料性质等方面的不同,这3种定义下的安全系数取值标准应有所不同。基于这一背景,应用可靠度分析理论,探讨锚杆抗拔在同一可靠度(失效概率)条件下,这3种定义的安全系数的差别,并为相关规程的修订工作中的锚杆抗拔安全系数取值标准的确定提供科学依据。

In the existing specifications and codes, the factor of safety of anchor against pull-out is generally defined by considering tensile strength of steel bar/strand, bond strength of grout and the steel bar/strand, and bond strength of grout and surrounding rock/soil. It results in three different types of factors of safety, which are being applied in practice. The current China＇s specifications and codes suggest the same allowable value for the above three different types of factors of safety. Actually, there is quite difference among them due to different pull-out failure mechanisms of tendon. In view of this limitation, the difference among them is studied and discussed under the same reliability （or failure probability） by using the reliability analysis, and the criteria for determining the factor of safety of anchor against pull-out are proposed.