往复荷载作用下滨海滩涂软基长期性能劣化机制试验研究  

Experimental Study on Long-term Performance Deterioration Mechanism of Coastal Mudflat Soft Foundation Under Cyclic Loading

作　　者：肖汉清 赵斌 熊力 陈令 秦朗 刘杰 XIAO Hanqing;ZHAO Bin;XIONG Li;CHEN Ling;QIN Lang;LIU Jie(Power China Chongqing Engineering Co.Ltd.,Chongqing 400060,China;Ruibo New Energy Group Co.Ltd.,Taizhou 318014,Zhejiang China;Sichuan Chengnan Expressway Co.Ltd.,Chengdu 610051,China;State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Science,Wuhan 430071,China)

机构地区：[1]中国电建集团重庆工程有限公司,重庆400060 [2]锐博新能源集团有限公司,浙江台州318014 [3]四川成南高速公路有限责任公司,成都610051 [4]中国科学院武汉岩土力学研究所,武汉430071

出　　处：《河南科学》2024年第9期1325-1333,共9页Henan Science

基　　金：四川省交通运输科技项目(2021-ZL-05)。

摘　　要：淤泥属于软土范畴,具有超高含水量、高触变性、高压缩性、抗剪强度低、地基承载力低、土体结构性差等特性,工程地质条件极差,正确认识软黏土的基本物理力学特性和强度特性具有重要的工程意义.以浙江省台州市沿海滩涂软基为研究对象,开展往复荷载作用下滩涂软土的室内物理特性以及静动态响应试验.通过考虑荷载振动波形、幅值、围压等多种影响因素,阐明动荷载作用下土体超孔隙水压上升、有效应力减少的发生机理,进而获得滨海滩涂软基长期性能的劣化机制与规律.研究结果表明:在长期往复荷载作用下,软土累积塑性应变历经了快速增长→匀速增加→衰减稳定3个阶段的变化.在荷载初期作用下,软土地基土体的累积变形较大,但随着荷载作用时间的增长,土体逐渐趋于密实,其变形速率逐渐减小,累积变形和累积孔压最终趋于稳定.随着往复次数的增加,孔压的增长幅度及速度逐渐减弱,最终达到稳定值.相同波形下,加载持续时间越长或间歇时间越短,累积塑性应变和累积孔压越大.随着振动频率的增加,累积塑性应变和累积孔压逐渐减小,频率越大,累积塑性应变曲线和累积孔隙水压力曲线越先达到稳定.围压、动应力幅值是影响软基长期性能的重要因素.Mud is a type of soft soil characterized by extremely high-water content,high thixotropy,high compressibility,low shear strength,low bearing capacity,and poor soil structure.These geological conditions are extremely poor for engineering purposes.Mud is widely distributed in coastal and riverside areas of China and is closely related to engineering constructions such as ports,airports,roads,and tunnels.A proper understanding of the basic physical and mechanical properties,as well as the strength characteristics of soft clay,is of significant engineering importance.This paper focuses on the coastal tidal flat soft soil in Taizhou,Zhejiang Province,China,and conducts indoor physical property tests and static-dynamic response experiments under cyclic loading.By considering various factors such as load vibration frequency,waveform,amplitude,and confining pressure,this study elucidates the mechanisms of excess pore water pressure increase and effective stress reduction in soil under dynamic loading.Consequently,the degradation mechanisms and patterns of long-term performance of coastal tidal flat soft soils are identified.The research results indicate that under long-term cyclic loading,the cumulative plastic strain of the soil goes through three stages:rapid growth,uniform increase,and stable decline.Initially,the cumulative deformation of the soft soil foundation is relatively large,but as the load duration increases,the soil gradually densifies,and its deformation rate decreases,leading to the eventual stabilization of cumulative deformation and pore pressure.As the number of loading cycles increases,the rate and magnitude of pore pressure growth gradually weaken,eventually reaching a stable value.

关 键 词：淤泥 软基 动静态三轴 孔隙水压力 劣化机制 

分 类 号：TU447[建筑科学—岩土工程]