侧限约束下回填砂分级加卸载力学响应  

Mechanical response of grading loading and unloading of backfill sand under confinement constraint

作　　者：王冬冬 李顺群 王理想 WANG Dongdong;LI Shunqun;WANG Lixiang(School of Civil Engineering,Tianjin Chengjian University,Tianjin 300384,P.R.China;Water Resources Research Institute of Anhui Province and Huaihe Water Resources Committee,Ministry of Water Resources,Bengbu 233002,Anhui Province,P.R.China)

机构地区：[1]天津城建大学土木工程学院,天津300384 [2]安徽省(水利部淮河水利委员会)水利科学研究院,安徽蚌埠233002

出　　处：《深圳大学学报（理工版）》2023年第5期571-577,I0003,共8页Journal of Shenzhen University(Science and Engineering)

基　　金：天津市重点研发计划资助项目(19YFZCSF00820);安徽省自然科学基金资助项目(2208085US01)。

摘　　要：在公路路基和水利堤防工程中时常出现因回填砂压实不密造成局部沉陷的破坏问题.为降低此类破坏发生的可能性,利用三维应力-应变测试技术,开展轴对称条件下回填砂压实过程的力学响应研究.结合数值分析软件,对采集到的原始数据进行矩阵求解,并对循环荷载作用下的应力、应变、静止土压力系数以及应力-应变路径进行分析.试验结果表明,对于回填砂来说,压实次数并非越多越好,而是存在一个最优压实次数值;在试验初始阶段,随着循环次数增加,静止土压力系数增大,即砂土内部水平方向密实度增大;当循环次数大于6时,静止土压力系数不再增加.在一维竖向荷载作用下,荷载法向面内有效正应力响应落后于荷载平行面内有效正应力响应,建议压实过程中控制压实速率,做到有效竖向压实和水平向挤压.分析应力路径和应变路径可知,不同加载吨位和压实方式(不同形式荷载)会影响应力路径,进而影响应变形变.研究结果可为砂土作为填方材料的力学性能提供借鉴,也为实际工程中原位三维应力-应变研究提供参考.In subgrade and levee projects,local subsidence problems often occur due to insufficient compaction of backfill sand.In order to reduce the possibility of such damage,the three-dimensional stress-strain testing technology is used to study the mechanical response of backfill sand compaction under axisymmetric conditions.The collected raw data is calculated using mathematical analysis software,and the stress,strain,K0 value and stressstrain path are analyzed under cyclic loading.The studies show that more compaction is not better,but there exist an optimal number of compaction times for backfill sand.In the initial stage of the test,as the number of cycle increases,the coefficient of earth pressure at rest increase,that is,the density inside the sand increases;when cycle index is greater than 6,the coefficient of earth pressure at rest no longer increases.Under the action of onedimensional vertical load,the effective normal stress response in the normal direction of plane of the load lags behind the effective normal stress in the parallel plane of the load.Therefore,it is recommended to control the compaction rate during the compaction process to achieve effective vertical compaction and horizontal extrusion.In addition,different loading tonnages and compaction methods(different forms of load)will affect the stress path,and then affect the strain deformation.The research results can provide objective reference for the mechanical properties of sand as filling material,and also provide reference for in-situ three-dimensional stress-strain research in practical engineering.

关 键 词：岩土工程 应力-应变 循环加载 压实试验 应力路径 三维土压力盒 局部沉陷 

分 类 号：TU411.3[建筑科学—岩土工程]