循环荷载下深海能源含气土动力特性试验研究  

Experimental study on dynamic characteristics of deep-sea energy gas-bearing soil under cyclic loading

作　　者：王滢 李朋飞 孔祥霄 WANG Ying;LI Pengfei;KONG Xiangxiao(College of Civil Engineering and Architecture,Shandong University of Science and Technology,Qingdao 266590,China;Key Laboratory of Civil Engineering Disaster Prevention and Mitigation,Shandong University of Science and Technology,Qingdao 266590,China)

机构地区：[1]山东科技大学土木工程与建筑学院,山东青岛266590 [2]山东科技大学山东省土木工程防灾减灾重点实验室,山东青岛266590

出　　处：《山东科技大学学报（自然科学版）》2024年第2期30-39,共10页Journal of Shandong University of Science and Technology(Natural Science)

基　　金：山东省自然科学基金项目(ZR2021ME144)。

摘　　要：以往对深海能源含气土的研究多以静荷载作用为主,且含气土的气泡尺寸多为不可控的离散小气泡。本研究提出一种能够控制含气量及气泡大小的制样方法,并对含有离散大气泡的深海能源含气土开展固结不排水循环加载动三轴试验,分析深海能源含气土在不同循环应力比(cyclic stress ratio, CSR)、有效围压、饱和度和黏土含量条件下的累积塑性应变、滞回曲线、动孔压和动强度发展规律。结果表明:累积塑性应变分为“稳定增长型”和“失稳破坏型”两类,累积塑性应变增长速率随着CSR增大、饱和度下降、围压增大和黏土含量增加而加快。含气土的滞回圈随振次增加、饱和度下降、围压增大及黏土含量增加,呈现出回弹模量降低、阻尼比增大的现象。含气土动孔压发展模式分为“缓慢增长型”和“孔压骤增型”,孔压增长速率随饱和度下降、CSR增大及黏土含量增加而加快,且在循环荷载作用下,动孔压均未达到有效应力水平,即在轴向应变达到5%前,试样未现液化破坏现象。动强度随饱和度降低而下降,且下降幅度随饱和度的降低,呈现出增大的趋势。Previous studies on deep-sea energy gas-bearing soil mainly focus on static load effects and uncontrollable discrete small bubbles of gas-bearing soil in size.In this study,a sample preparation method for controllable gas content and bubble size was proposed and consolidated undrained cyclic loading dynamic triaxial tests were conducted on deep-sea energy gas-bearing soil containing discrete large bubbles to analyze the cumulative plastic strain,hysteresis curve,dynamic pore pressure,and dynamic strength development of deep-sea energy gas-bearing soil under different cyclic stress ratios(CSR),effective confining pressures,saturation levels,and clay contents.The results show that the cumulative plastic strain can be divided into“stable growth type”and“unstable failure type”.The rate of cumulative plastic strain growth increases with the the decrease of saturation and the increase of CSR,confining pressure,and clay content.The hysteresis loop of gas-bearing soil increases with the decrease of saturation and the increase of vibration frequencies,confining pressure and clay content,showing a decrease in elastic modulus and an increase in damping ratio.The development mode of dynamic pore pressure in gas-bearing soil can be divided into“slow growth type”and“sudden increase type”.The rate of pore pressure growth accelerates with the decrease of saturation and the increase of CSR and clay content.Moreover,under cyclic loading,the dynamic pore pressure does not reach the same level as the effective stress,that is,no liquefaction failure phenomena occur to the sample before the axial strain reaches 5%.The dynamic intensity decreases with the decrease of saturation and the decrease magnitude shows an increasing trend with the decrease of saturation.

关 键 词：深海能源土 含气土 动力特性 动三轴试验 位移判别标准 

分 类 号：TU411[建筑科学—岩土工程]