穿越岩土交界面竖井结构水平地震损伤破坏模式

The damage and failure mode of shaft structures crossing the geotechnical interface under the horizontal excitation of earthquake motion

已有竖井震害实例表明,强震作用下地下竖井结构安全遭受严重威胁且在岩土交界面附近出现损伤破坏。在实际工程中竖井不可避免地要穿越岩土交界面,而穿越岩土交界面竖井结构地震损伤破坏模式尚未明确,本研究主要开展水平向地震作用下竖井衬砌强度和厚度参数对竖井损伤破坏模式研究。基于有限元软件ABAQUS建立岩土交界段场地竖井结构三维土结相互作用模型,采用三维动力时程分析方法研究水平向地震作用下竖井结构内力分布、直径变形率以及损伤状态和应变分布规律。结果表明:竖井轴力、剪力和弯矩均在岩土交界面处产生突变,轴向轴力在岩土交界面位置处为拉力,环向轴力为压力;竖井损伤位置集中在岩土交界面处且破坏模式为轴向受拉损伤破坏,轴向轴力起损伤控制作用,随竖井衬砌强度和厚度增加,受拉损伤加重;竖井轴向应变峰值集中在岩土交界面处;C35混凝土强度下竖井衬砌壁厚0.6 m工况下的轴向应变为0.5 m壁厚工况的1.3倍。

Previous seismic damage of the underground shafts have shown that the structural safety of shaft are facing seriously threat under strong earthquakes and damage occurs near the rock soil interface.In actual engineering,the shaft inevitably crossed the geotechnical interface,and the seismic damage failure mechanism of the shaft structure at the site of the geotechnical interface had not yet been clarified.This research mainly studied the influence of the shaft lining strength and thickness parameters on the damage of the shaft under the horizontal earthquake motion.Based on the finite element software ABAQUS,a three-dimensional soil structure interaction model of shaft was established.The internal force distribution,diameter deformation rate,damage state and strain distribution of the shaft under the action of horizontal earthquake motion were studied by three-dimensional dynamic time history analysis method.The results showed that the axial force,shear force and bending moment of the shaft at the geotechnical interface were mutated,the axial thrust force was the tensile force at the geotechnical interface,while the hoop force was the pressure force.The damage position of the shaft was concentrated at the intersection of rock and soil and was manifested as tensile damage;The axial thrust force is the damage control force,and the axial tensile damage was aggravated as the strength and thickness of the shaft lining increased;The peak axial strain of the shaft was concentrated at the geotechnical interface;The axial strain of the shaft lining with a wall thickness of 0.6 m under C35 concrete strength was 1.3 times that under a wall thickness of 0.5 m.