摘要
土工袋因其优良的工程性能被应用于寒区膨胀土渠道边坡的冻害防治,而土工袋-渠坡膨胀土界面间的力学行为是影响渠坡方案设计的关键因素。利用自研的大型温控直剪试验装置,开展了正负温条件下不同初始含水率土工袋-渠坡膨胀土试样的界面剪切试验,研究了温度和含水率对试样界面的破坏形态、剪切应力-剪切位移曲线、强度特征和剪胀规律的影响。试验结果表明:冻结试样的破坏特征均为典型的强应变软化型,常温试样则呈现弱应变软化和弱应变硬化两种破坏特征;冻结状态下,随着土体初始含水率增加,试样的峰值强度、界面黏聚力逐渐增大,而残余强度与界面摩擦角几乎不受影响;常温状态下,试样的峰值强度、残余强度、界面黏聚力与摩擦角均随土体含水率的增加而减小;此外,冻结试样的法向位移随剪切位移的增加呈现三段式增长趋势,其在整个剪切过程中始终表现为剪胀;常温试样的法向位移-剪切位移曲线较为平滑,整体表现为低法向应力下剪胀、高法向应力下剪缩,但在相同的法向应力下,处于最优含水率试样的最终剪胀量最小。
Soilbags have been used to prevent frost damage to canal expansive soils in cold regions.The mechanical characteristics of the interface between soil bags and canal expansive soil is a key factor for the design of the canal slope.The direct shear tests of soilbag-expansive soil interface with various water contents under positive and negative temperatures are conducted by a self-developed direct shear test device.Effects of temperature and water content on shear characteristics of the interface are studied.Test results show that:frozen samples exhibit typical strain softening failure,while the samples under positive temperatures show two failure patterns of weak strain softening and hardening.Under negative temperatures,as water content rises,peak shear strength and interfacial cohesion increase gradually,while the residual shear strength is almost unaffected.Under positive temperatures,peak and residual shear strength,interfacial cohesion and friction angle decrease with increasing water contents.Normal displacement of the frozen sample demonstrates a three-stage growth trend and exhibits shear dilatancy behavior.At positive temperatures,the sample shows shear dilatancy under low stress and shear contraction under high stress.Under identical normal stress,samples with optimal moisture content demonstrate the least final dilatancy displacement.
作者
田金博
张勇敢
鲁洋
刘斯宏
刘瑾
武猛
TIAN Jinbo;ZHANG Yonggan;LU Yang;LIU Sihong;LIU Jin;WU Meng(College of Water Conservancy and Hydropower Engineering,Hohai University,Nanjing 210024,China;School of Earth Sciences and Engineering,Hohai University,Nanjing 211100,China;International Joint Laboratory of Long-term Behavior&Environmentally Friendly Rehabilitation Technologies on Dams,Hohai University,Nanjing 210024,China;National Key Laboratory of Water Disaster Prevention,Hohai University,Nanjing 210024,China)
出处
《岩土工程学报》
北大核心
2025年第9期1946-1955,共10页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(52109123,52479099)
中央高校基本科研业务费专项资金项目(B220203029)。
关键词
渠坡膨胀土
土工袋
直剪试验
破坏形态
强度特征
剪胀规律
canal expansive soil
soilbag
direct shear test
failure morphology
strength behavior
dilatancy characteristic
