低应力状态下干湿-冻融循环对季冻区膨胀土强度的影响
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摘要
考虑渠道浅层土体的实际应力状态,开展了一系列低围压下的三轴固结不排水剪切试验,分别研究了干湿循环、冻融循环和干湿-冻融循环三种环境作用对取自黑龙江大庆的膨胀土的应力-应变关系和抗剪强度的影响。结果表明,在低围压下:未经历和经历了三种循环作用的试样,其应力-应变曲线总体上表现为弱应变软化型或应变稳定型;相同围压下,经历了三种循环作用的试样均随作用次数的增加,产生破坏强度明显降低的现象,其中经历干湿-冻融循环的试样在作用8次后趋于稳定,其试样破坏强度降低的幅度最大;经历三种循环作用后,试样黏聚力均呈指数型衰减,而内摩擦角变化不大,其中经历干湿-冻融循环作用的试样黏聚力衰减程度最大。
Considering the actual stress state of shallow soil, a series of triaxial consolidated undrained sheer tests were conducted on an expansive soil from a channel slope in Daqing, Heilongjiang Province, China under low confining stresses to investigate the influences of wetting-drying and freezing-thawing cycles on the stress-strain behavior, and shear strength of Daqing expansive soil. The results showed that: The stress-strain behavior of the expansive soil specimens is generally strain-softening. As the number of cycles increases, the shear strength of specimens decreases significantly. The shear strengths of the specimen softening undergoing eight wetting-drying and freezing-thawing cycles are basically stable, and suffering greatest alterations on shear strength. After cyclic treatments, the cohesion of samples decreases exponentially and those subjected to wetting-drying and freezing-thawing cycles suffer greater alterations on cohesion, while the internal friction angle remained relatively constant.
Considering the actual stress state of shallow soil, a series of triaxial consolidated undrained sheer tests were conducted on an expansive soil from a channel slope in Daqing, Heilongjiang Province, China under low confining stresses to investigate the influences of wetting-drying and freezing-thawing cycles on the stress-strain behavior, and shear strength of Daqing expansive soil. The results showed that: The stress-strain behavior of the expansive soil specimens is generally strain-softening. As the number of cycles increases, the shear strength of specimens decreases significantly. The shear strengths of the specimen softening undergoing eight wetting-drying and freezing-thawing cycles are basically stable, and suffering greatest alterations on shear strength. After cyclic treatments, the cohesion of samples decreases exponentially and those subjected to wetting-drying and freezing-thawing cycles suffer greater alterations on cohesion, while the internal friction angle remained relatively constant.
引文
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[17] 邹维列,陈轮,谢鹏,等.重塑膨胀土非线性强度特性及一维固结浸水膨胀应力-应变关系[J].岩土力学,2012,33(S2):59-64.
[2] Liu J K,Chang D Y,Qian M.Influence of freeze-thaw cycles on mechanical properties of a silty sand[J].Engineering Geology,2016,210:23-32.
[3] 张泽,马巍,齐吉琳.冻融循环作用下土体结构演化规律及其工程性质改变机理[J].吉林大学学报(地球科学版),2013,43(6):1904-1914.
[4] 杨和平,王兴正,肖杰.干湿循环效应对南宁外环膨胀土抗剪强度的影响[J].岩土工程学报,2014,36(5):949-954.
[5] 许雷,刘斯宏,鲁洋,等.冻融循环下膨胀土物理力学特性研究[J].岩土力学,2016,37(S2):167-174.
[6] Shi B,Jiang H T,Liu Z B,et al.Engineering geological characteristics of expansive soils in China[J].Engineering Geology,2002,67(1):63-71.
[7] 龚壁卫,程展林,郭熙灵,等.南水北调中线膨胀土工程问题研究与进展[J].长江科学院院报,2011,28(10):134-140.
[8] 龚壁卫,程展林,胡波,等.膨胀土裂隙的工程特性研究[J].岩土工程学报,2014,25(7):1825-1836.
[9] 陈善雄,余颂,孔令伟,等.中膨胀土路堤包边方案及其试验验证[J].岩石力学与工程学报,2006,25(9):1777-1783.
[10] 杨和平,章高峰.包盖法填筑膨胀土路堤的合适包边宽度[J].公路交通科技,2008,25(7):37-42.
[11] 殷宗泽,袁俊平,韦杰,等.论裂隙对膨胀土边坡稳定的影响[J].岩土工程学报,2012,34(12):2155-2161.
[12] 包承纲.非饱和土的性状及膨胀土边坡稳定问题[J].岩土工程学报,2004,26(1):1-15.
[13] 吕海波,曾召田,赵艳林,等.膨胀土强度干湿循环试验研究[J].岩土力学,2009,30(12):3797-3802.
[14] 刘锦程,张艳美,张笑峰.干湿循环对非饱和土特性影响研究现状与展望[J].水利与建筑工程学报,2017,15(5):69-75.
[15] 唐朝生,施斌.干湿循环过程中膨胀土的胀缩变形特征[J].岩土工程学报,2011,33(9):1376-1384.
[16] 张家俊,龚壁卫,胡波,等.干湿循环作用下膨胀土裂隙演化规律试验研究[J].岩土力学,2011,32(9):2729-2734.
[17] 邹维列,陈轮,谢鹏,等.重塑膨胀土非线性强度特性及一维固结浸水膨胀应力-应变关系[J].岩土力学,2012,33(S2):59-64.