压实红层泥岩填料强度与刚度软化和衰减特性研究  

Study on stiffness softening and attenuation characteristics of compacted red mudstone

作　　者：刘先峰[1,2,3] 潘申鑫 袁胜洋 陈康[1,2] 马杰 陈忆涵[1,2] LIU Xianfeng;PAN Shenxin;YUAN Shengyang;CHEN Kang;MA Jie;CHEN Yihan(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China;Key Laboratory of High-Speed Railway Engineering of Ministry of Education,Southwest Jiaotong University,Chengdu 610031,China;School of Civil Engineering,Xinjiang Institute of Engineering,Urumqi 830023,China)

机构地区：[1]西南交通大学土木工程学院,四川成都610031 [2]西南交通大学高速铁路线路工程教育部重点实验室,四川成都610031 [3]新疆工程学院土木工程学院,新疆乌鲁木齐830023

出　　处：《铁道科学与工程学报》2022年第9期2629-2636,共8页Journal of Railway Science and Engineering

基　　金：四川省科技计划项目(2021YJ0036,2019S170111);中国铁道科学研究院国家创新平台开放基金资助项目(2020YJ105);中央高校基本科研项目(2682020CX68)。

摘　　要：全风化红层泥岩作为基床以下的路基本体填料的适用性已被证实,但路基结构若能全部采用全风化红层泥岩填料填筑将对西南地区的高速铁路建设具有重大意义。为研究全风化红层泥岩作为路基基床浅层填料的适用性,对不同含水率和干密度的全风化红层泥岩进行低围压(5 kPa)三轴不固结不排水(UU)剪切实验,明确干密度和含水率对全风化红层泥岩填料强度的影响,揭示低围压下全风化红层泥岩填料的力学特性。根据全风化红层泥岩填料刚度衰减特性建立考虑含水率和干密度的刚度衰减双曲线模型,分析含水率和干密度与模型指标之间的关联性。研究结果表明:低围压下全风化红层泥岩填料达到峰值强度后强度显著衰减,应力-应变关系曲线呈现明显的强软化型,峰值应力受含水率和干密度影响较大。在最优含水率下全风化红层泥岩填料压实度达到K95时强度满足高速铁路路基基床填料要求,但遇水后强度和刚度均出现了明显的软化现象,将其作为基床浅层填料时必须做好防水措施。低围压下全风化红层泥岩填料刚度先后经历了缓慢减小、迅速下降和基本维持不变3个阶段,含水率和干密度只影响填料的初始刚度和刚度衰减速率,而对填料的残余刚度影响较小。研究结果可为高速铁路全风化红层泥岩基床填料设计提供相关参考依据。Fully weathered red mudstone has been confirmed to be appropriate as the filling materials for the lower part of subgrade.If subgrade is built completely by fully weathered red mudstone,it would generate significant effect on the construction of high-speed railway in southwest China.In this paper,in order to study the applicability of fully weathered red mudstone as the shallow filler of subgrade bed,the triaxial unconsolidated undrained(UU)shear test under low confining pressure(5 kPa)was carried out on fully weathered red mudstone with different water contents and dry densities.The influence of dry density and water content on fully weathered red mudstone filler was clarified,and the mechanical properties of fully weathered red mudstone filler under low confining pressure were revealed.The results show that the strength of fully weathered red mudstone filler decreases significantly after reaching the peak strength under low confining pressure,and the stress-strain relationship curve shows obvious strong softening type.The peak stress is greatly affected by water content and dry density.Under the optimal water content,when the compaction degree of fully weathered red mudstone filler reaches K95,the strength meets the requirements of high-speed railway subgrade bed filler,but the strength and stiffness are obviously softened after water.When it is used as shallow filler of subgrade bed,waterproof measures must be done.The stiffness of the fully weathered red mudstone filler at low confining pressure undergoes three successive stages of slow decrease,rapid decrease and basic maintenance,the water content and dry density only affect the initial stiffness andthe rate of stiffness decay of the filler but have less influence on the residual stiffness.Finally,according to the stiffness attenuation characteristics of fully weathered red mudstone filler,the hyperbolic model of stiffness attenuation considering water content and dry density is established.The correlation between water content and dry density and model ind

关 键 词：高速铁路 全风化红层泥岩 峰值应力 割线模量 软化特性 

分 类 号：TU443[建筑科学—岩土工程]