南水北调与水利科技
南水北調與水利科技
남수북조여수리과기
South-to-North Water Transfers and Water Science & Technology
2015年
5期
922-925
,共4页
许雷%鲁洋%宗佳敏%宋迎俊
許雷%魯洋%宗佳敏%宋迎俊
허뢰%로양%종가민%송영준
膨胀土%冻融循环%直剪试验%体积变化%干密度%含水率
膨脹土%凍融循環%直剪試驗%體積變化%榦密度%含水率
팽창토%동융순배%직전시험%체적변화%간밀도%함수솔
expansive clay%freeze-thaw cycle%direct shear test%volume change%dry density%water content
我国南水北调中线工程沿线的部分膨胀土渠道处在季节性冻土地区。为了探究冻融循环对膨胀土抗剪强度和体积变化的影响规律，对经历冻融循环的膨胀土和非膨胀性黏土试样进行尺寸测量和直剪试验。试验结果表明：在冻融循环初始阶段，土体抗剪强度的降低较为明显，随后由于含水率的降低，土体的强度逐渐增强；在冻融循环的过程中，非膨胀性黏土的体积变化表现为“冻胀融沉”，而膨胀土的体积变化表现为“冻缩融胀”。干密度的改变不影响膨胀土的抗剪强度和体积变化的规律形态，干密度大的膨胀土最终体缩量较小。采取防蒸发措施的膨胀土在冻融循环前3次抗剪强度逐渐减小，随后趋于稳定，其最终体积几乎不受干缩的影响。
我國南水北調中線工程沿線的部分膨脹土渠道處在季節性凍土地區。為瞭探究凍融循環對膨脹土抗剪彊度和體積變化的影響規律，對經歷凍融循環的膨脹土和非膨脹性黏土試樣進行呎吋測量和直剪試驗。試驗結果錶明：在凍融循環初始階段，土體抗剪彊度的降低較為明顯，隨後由于含水率的降低，土體的彊度逐漸增彊；在凍融循環的過程中，非膨脹性黏土的體積變化錶現為“凍脹融沉”，而膨脹土的體積變化錶現為“凍縮融脹”。榦密度的改變不影響膨脹土的抗剪彊度和體積變化的規律形態，榦密度大的膨脹土最終體縮量較小。採取防蒸髮措施的膨脹土在凍融循環前3次抗剪彊度逐漸減小，隨後趨于穩定，其最終體積幾乎不受榦縮的影響。
아국남수북조중선공정연선적부분팽창토거도처재계절성동토지구。위료탐구동융순배대팽창토항전강도화체적변화적영향규률，대경력동융순배적팽창토화비팽창성점토시양진행척촌측량화직전시험。시험결과표명：재동융순배초시계단，토체항전강도적강저교위명현，수후유우함수솔적강저，토체적강도축점증강；재동융순배적과정중，비팽창성점토적체적변화표현위“동창융침”，이팽창토적체적변화표현위“동축융창”。간밀도적개변불영향팽창토적항전강도화체적변화적규률형태，간밀도대적팽창토최종체축량교소。채취방증발조시적팽창토재동융순배전3차항전강도축점감소，수후추우은정，기최종체적궤호불수간축적영향。
Part of expansive clay channel in the Middle Route of South-to-North Water Transfer Project (SNWTP)in China is located in the seasonal frozen soil region.In order to investigate the effects of freeze-thaw cycle on the shear strength and vol-ume change of expansive clay,direct shear test was conducted on the expansive and non-expansive clay samples which had expe-rienced the freeze-thaw cycle,and then the sizes of samples were measured.The results showed that (1)the shear strength de-creases gradually at the initial stage of freeze-thaw cycle and then increases gradually with the decreasing of water content;(2) during the process of freeze-thaw cycle,the volume change of non-expansive clay appears as "frost heaving and thaw collap-sing",while the volume change of expansive clay appears as"frost shrinking and thaw expanding";(3)the variation of dry den-sity does not affect the shear strength and volume change of clay,and the expansive clay with higher dry density has smaller fi-nal volume shrinkage;and (4)the shear strength of expansive clay with water retention measure decreases gradually at the first three freeze-thaw cycles,then tends to be stable,and its final volume is not affected by drying shrinkage.
