高烈度地震区抗滑桩锚固深度可靠度分析

Analysis on Reliability of Anchoring Depth of Anti-sliding Pile in High-intensity Earthquake Region

在高烈度地震区,地震作用对抗滑桩的影响并没有引起人们的足够重视,这将大大降低工程运行可靠度。针对地震区抗滑桩设计,对影响锚固深度的容许侧应力进行地震角修正,建立地震作用下的抗滑桩侧应力计算模型,确定承载能力极限状态下的侧应力功能函数,把桩周岩土介质参数、桩体结构强度和地震作用等作为随机变量,采用一次二阶矩法,进行可靠性指标计算。通过工程实例,得出在一定锚固深度下,岩土参数变异性、考虑和不考虑地震作用条件下对抗滑桩可靠度的影响,获得高烈度地震区抗滑桩设计中的锚固深度取值标准,并提出抗滑桩设计以可靠度法设计指导定值法设计的新思路。

The effect of seismic action on anti-sliding pile in high-intensity earthquake region has not attracted enough attentions, which will reduce the reliability in project operation greatly. In connection with the design of anti-sliding pile in earthquake region, seismic angle correction is carried out against the allowable lateral stress affecting the anchoring depth to establish the model calculating lateral stress on anti-sliding pile under seismic action and determine the function of the lateral stress in the state of ultimate bearing capacity. Taking parameters of geo-materials surrounding pile, structural strength of pile body and seismic action as random variables, and by use of FOSM method, the index of reliability is calculated. Through case study, under certain anchoring depth, either the effect of soil parameter＇s variety or the conditions with or without the consideration of seismic action on anti-sliding pile＇s reliability can be known, the valuing standard of anchoring depth in the design of anti-sliding pile in high-intensity earthquake region can be obtained, and the new idea taking reliability as the guidance of valuation in design of anti-sliding pile is proposed.