浑水渗流对黏性土内贯穿性裂缝修复演化研究  

Evolution of perforated cracks in cohesive soil under muddy water seepage

作　　者：何涛 毛海涛 张超[2] 谷易 HE Tao;MAO Hai-tao;ZHANG Chao;GU Yi(College of Urban and Rural Construction,Shanxi Agricultural University,Jinzhong,Shanxi 030600,China;School of Civil Engineering,Chongqing Three Gorges University,Chongqing 404120,China)

机构地区：[1]山西农业大学城乡建设学院,山西晋中030600 [2]重庆三峡学院土木工程学院,重庆404120

出　　处：《岩土力学》2023年第9期2628-2638,共11页Rock and Soil Mechanics

基　　金：国家自然科学青年基金(No.42207102);山西省自然科学基金面上项目(No.202103021224151,No.202103021223132);山西农业大学省改革高层次人才引进项目(No.2021XG009)。

摘　　要：以黏性土为主要物源的大坝防渗体,常会因为极端温差、不均匀沉降等原因出现贯穿性裂缝进而诱发渗流破坏,水力充填和淤堵是一种经济有效的修复方法。为深入研究其修复机制,以重塑黏性土为研究对象,在土体内预制裂缝以模拟防渗体开裂,系统研究了浑水浓度、水头、渗流方向(即水平、竖直、斜向)、反滤层不均匀系数等因素对裂缝修复的影响,对裂缝修复时缝内流体的运动状态进行了判定,并基于数字图像处理技术开展了裂缝在浑水渗流作用下的演化规律研究。结果表明:在浑水渗流作用下,黏性土内裂缝修复过程可分为3个阶段,分别是过渡期(阶段1)、修复期(阶段2)和稳定期(阶段3);裂缝修复过程会影响裂缝中流体的渗流特性,阶段1、阶段2内的流体运动规律满足Forchheimer流动,阶段3内的流体运动规律符合Darcy流,且阶段3的起点为流态转捩的临界点,可根据裂缝内流态的变化判断裂缝修复所处阶段;浑水浓度、水头、裂缝形式、反滤层不均匀系数为裂缝修复的主要影响因素,在高浓度、低水头下裂缝修复所需时间最短;裂缝修复后的渗出量Q、流速υ相比修复前均显著降低,分别降低99.83%、99.98%,而水力梯度J明显增加,增长幅度为27.92倍,修复后的土体抗渗性能明显增强。研究成果对于大坝防渗体裂缝的演化机制与防治措施具有一定的理论指导价值。The dam anti-seepage body with cohesive soil as the main source often has perforated cracks due to extreme temperature difference,uneven settlement and other reasons,which eventually induces seepage failure.Hydraulic filling and clogging is an economical and effective repair method.In order to understand its repair mechanism,this paper takes the remolded cohesive soil as the research object,prefabricates cracks in the soil to simulate the cracking of the impermeable body,and studies the effects of muddy water concentration,water head,seepage direction(i.e.horizontal,vertical,oblique),non-uniformity coefficient of the filter layer and other factors on crack repair.The motion state of the fluid in the crack during crack repair was determined,and the evolution law of the crack under the action of muddy water seepage was studied based on digital image processing technology.The results show that under the action of muddy water seepage,the crack repair process in cohesive soil can be divided into three stages:transition period(stage 1),repair period(stage 2)and stable period(stage 3).The crack repair process will affect the seepage characteristics of the fluid in the crack.The fluid motion law at stages 1 and 2 satisfies the Forchheimer flow,and the fluid motion law at stage 3 conforms to the Darcy flow.The starting point of stage 3 is the critical point of flow transition,and the stage of fracture repair can be judged according to the change of flow state in the crack.Muddy water concentration,water head,crack type and uneven coefficient of filter layer are the main influencing factors of crack repair.The time required for crack repair is the shortest under high muddy water concentration and low water head.The seepage quantity Q and flow velocityυ after the crack repair are significantly lower than those before the repair,which are reduced by 99.83%and 99.98%,respectively,while the hydraulic gradient J is significantly increased by 27.92 times,and the impermeability performance of the soil after the repair is signifi

关 键 词：浑水 贯穿性裂缝 水力充填 数字图像处理 抗渗性能 

分 类 号：TU411[建筑科学—岩土工程]