循环荷载下地铁隧道基底软岩动力变形试验研究

摘要

全风化砾岩是一种受剧烈风化作用形成的低强度软岩。通过对全风化砾岩进行动三轴循环加载试验，对低频循环荷载作用下的不可恢复累积塑性动应变的发展规律进行研究，并分析其受动应力幅值、静偏应力大小、围压影响、荷载频率的影响程度。研究结果表明：岩样的动力变形以临界应力为界，呈现稳定型和破坏型两种发展形式；在循环荷载作用下，全风化砾岩的累积塑性动应变显著影响因素是动应力幅值与静偏应力幅值；围压及荷载频率因素为次要影响因素。岩样的变形发展随轴向动应力和静偏应力增加而增大，并且达到稳定所需的加载时间愈长。%Weathered-conglomerate is a low-strength soft rock formed by intense weathering of a subway tunnel basement.Using dynamic triaxial cyclic loading test,the law of development of dynamic strain for weathered con-glomerate under cyclic loading was studied,while the influence degree of dynamic stress amplitude,static devia-tor stress,confining pressure impact and loading frequency on dynamic strain for weathered conglomerate was an-alyzed.The results showed that,the deformation development of weathering conglomerate could be divided into two categories,i.e.,stable and failure.Under cyclic loading,the significant factors affecting plastic dynamic strain were the dynamic stress and static deviator stress amplitude,whereas confining pressure and load frequency were secondary factors.The rock deformation increased with the axial dynamic stress and static deviator stress, and greater number of load applications is needed for reaching stable state.