旱涝急转下斜墙坝险情孕育及灾变过程离心模型试验研究  

Centrifugal model tests on danger incubation and catastrophic process of inclined wall dams under drought-flood abrupt alternation

作　　者：叶伟[1] 马福恒[1,3] 胡江 李子阳[1] 顾行文[2] YE Wei;MA Fuheng;HU Jiang;LI Ziyang;GU Xingwen(Dam Safety and Management Department,Nanjing Hydraulic Research Institute,Nanjing 210029,China;Geotechnical EngineeringDepartment,Nanjing Hydraulic Research Institute,Nanjing 210024,China;The National Key Laboratory of Water Disaster Prevention,Nanjing 210029,China)

机构地区：[1]南京水利科学研究院大坝安全与管理研究所,江苏南京210029 [2]南京水利科学研究院岩土工程研究所,江苏南京210024 [3]水灾害防御全国重点实验室,江苏南京210029

出　　处：《岩土工程学报》2023年第10期2100-2109,共10页Chinese Journal of Geotechnical Engineering

基　　金：中央级公益性科研院所基本科研业务费专项项目(Y721008);国家自然科学基金项目(U2243244)。

摘　　要：长历时、高强度干旱后遭遇极端暴雨诱发旱涝急转工况,为探究旱涝急转工况对上游黏土防渗体土石坝的致灾机理,首先基于土样试验,研究了影响黏土干缩裂缝扩展的关键因素,分析了干缩裂缝萌生、扩展演化过程;随后通过离心模型试验,明晰了旱涝急转下黏土防渗体缺陷产生至诱发工程失事的演进行为。研究结果显示,土体高初始含水率虽能限制干缩裂缝的产生,但也会在裂缝出现后造成土体内部出现高水势梯度,从而加快裂缝发育。离心模型试验中旱涝急转第一阶段的干旱过程使得黏土防渗体土体基质渗透性明显降低,但干旱引起的干缩裂缝减小了黏土防渗体有效渗径,削弱了黏土防渗体防渗性能;第二阶段的极端降雨造成库水位快速增长,导致含裂缝黏土防渗体发生了水力劈裂,裂缝贯穿防渗体使其完全丧失防渗性能。研究成果厘清了黏土斜墙坝材料性能改变-裂缝孕育险情-降雨触发灾变的旱涝急转工况致灾路径。The extreme rainstorm after long-term and high-intensity drought will lead to the drought-flood abrupt alternation(DFAA).In order to explore the disaster mechanism of the upstream clay impervious earth rock dams under DFAA,based on the soil sample tests,the key factors affecting the expansion of shrinkage cracks are studied,and the initiation,expansion and evolution process of shrinkage cracks at different stages are analyzed.Through the centrifugal model tests,the evolution behaviors from clay impervious body defects to engineering failures under DFAA are clarified.The results show that although the high initial water content of soil can limit the occurrence of dry shrinkage cracks,it will also cause high hydraulic gradient in the soil after the occurrence of cracks,thus accelerating the development of cracks.During the first stage of DFAA,the drought process significantly reduces the permeability of soil matrix,but the shrinkage cracks caused by drought reduce the effective seepage diameter of clay impervious core and weaken its impervious performance.The extreme rainfall at the second stage causes the rapid growth of the reservoir water level,which leads to the hydraulic fracturing of the clay impervious core with cracks.The cracks penetrate the impervious core,making it completely lose its anti-seepage performance.The test results clarify the disaster-causing path of DFAA:from the change of the material performance to the danger of crack incubation to the rainfall triggered disasters.

关 键 词：旱涝急转 裂缝演变 险情孕育 水力劈裂 灾变路径 

分 类 号：TU411[建筑科学—岩土工程] TV64[建筑科学—土工工程]