粉质黏土冻土三轴强度及本构模型研究
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摘要
通过对南京典型粉质黏土?10℃冻土在不同围压、固结方式、应力路径条件下的三轴试验,分析不同因素对三轴强度影响,结果表明:最大轴向偏应力随围压增大而线性增大,且重塑粉质黏土冻土的最大轴向偏应力随围压的增大速度大于原状粉质黏土冻土的增大速度;固结方式对内摩擦角影响较大,对黏聚力影响不大,先等压排水固结再冻结试样强度会大幅度提高;强度和弹性模量受应力路径影响,其中常规加载应力路径强度及弹性模量要大于卸载应力路径强度及弹性模量;基于Duncan-Chang模型建立考虑围压影响的冻结粉质黏土本构模型,参数a、b与围压呈负相关,获得原状粉质黏土以及先等压排水固结再冻结、先等压不排水固结再冻结和先冻结后固结重塑粉质黏土的破坏比均值分别为0.87、0.89、0.93和0.87。
At present, we usually take the soil test samples used in the project on the site and process them into a standard sample in the laboratory, then we freeze samples without pressure and carry out the three axis strength tests. But in the actual engineering, the soil is often frozen under pressures, and few of us have studied the strength differences between the two conditions. There are also few studies on the strength of three axis under different loading methods, so it is necessary to study the stress strain characteristics of Nanjing silty clay under different confining pressures, different consolidation methods and different stress paths. The results show that the maximum axial stress is linearly increased with the confining pressure, and the growth rate of remolded silty clay is larger than that of raw silty clay. The consolidation way has great influence on the friction angle, and less influence on cohesion. The friction angle of frozen remolded silty clay ranged from 21.94 to 28.22. The strength of the isobaric drainage consolidation followed by freezing specimen will be greatly improved; the strength and elastic modulus are affected by the stress path, and the strength and elastic modulus of loading stress path are greater than the unloading stress path. On the basis of Duncan-Chang model, we have established a new model considering the influence of the confining pressures. The damage ratio of the original silty clay and silty clay consolidated by isobaric drainage before freezing, consolidated by isobaric undrained before freezing and consolidated after freezing are 0.87, 0.89, 0.93 and 0.87, respectively.
At present, we usually take the soil test samples used in the project on the site and process them into a standard sample in the laboratory, then we freeze samples without pressure and carry out the three axis strength tests. But in the actual engineering, the soil is often frozen under pressures, and few of us have studied the strength differences between the two conditions. There are also few studies on the strength of three axis under different loading methods, so it is necessary to study the stress strain characteristics of Nanjing silty clay under different confining pressures, different consolidation methods and different stress paths. The results show that the maximum axial stress is linearly increased with the confining pressure, and the growth rate of remolded silty clay is larger than that of raw silty clay. The consolidation way has great influence on the friction angle, and less influence on cohesion. The friction angle of frozen remolded silty clay ranged from 21.94 to 28.22. The strength of the isobaric drainage consolidation followed by freezing specimen will be greatly improved; the strength and elastic modulus are affected by the stress path, and the strength and elastic modulus of loading stress path are greater than the unloading stress path. On the basis of Duncan-Chang model, we have established a new model considering the influence of the confining pressures. The damage ratio of the original silty clay and silty clay consolidated by isobaric drainage before freezing, consolidated by isobaric undrained before freezing and consolidated after freezing are 0.87, 0.89, 0.93 and 0.87, respectively.
引文
[1]Hu X D,Wang J T.The triaxial shear test of artificially frozen soils in tunnel construction of Hong Kong[J].Applied Mechanics and Materials,2013,353-356:1653-1656
[2]杜海民,马巍,张淑娟,等.三轴循环加卸载条件下高含冰冻结砂土变形特性试验研究[J].岩土力学,2017,38(6):1675-1681(Du Haimin,Ma Wei,Zhang Shujuan,et al.Experimental investigation on deformation characteristics of ice-rich frozen silty sands under triax[J].Rock and Soil Mechanics,2017,38(6):1675-1681(in Chinese))
[3]Yang Y G,Lai Y M,Chang X X.Laboratory and theoretical investigations on the deformation and strength behaviors of artificial frozen soil[J].Cold Regions Science and Technology,2010,64:39-45
[4]孙钦杰,李栋伟,王伸远.人工冻结含盐砂土三轴剪切试验研究[J].煤炭技术,2015,34(4):105-107(Sun Qinjie,Li Dongwei,Wang Shenyuan.Test on triaxial shear of artificial frozen saline sand[J].Journal of China coal society,2015,34(4):105-107(in Chinese))
[5]赖远明,程红彬,高志华,等.冻结砂土的应力-应变关系及非线性莫尔强度准则[J].岩石力学与工程学报,2007,26(8):1612-1617(Lai Yuanming,Cheng Hongbing,Gao Zhihua,et al.Stress-strain relationships and nonliner mohr strength criterion of frozen sand clay[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(8):1612-1617(in Chinese))
[6]常小晓,马巍,王大雁.高围压下冻结粘土的抗压强度试验研究[J].冰川冻土,2007,29(4):636-639(Chang Xiaoxiao,Ma Wei,Wang Dayan.Study on the strength of frozen clay at high confining pressure[J].Journal of Glaciology and Geocryology,2007,29(4):636-639(in Chinese))
[7]李瑞宽,吴志坚,梁庆国,等.考虑微结构特征的黄土动力特性影响因素研究[J].工程地质学报,2018,26(4):905-914(Li Ruikuan,Wu Zhijian,Liang Qingguo,et al.Influence factors of dynamic characteristics of loess considering the microstructure properties[J].Journal of Engineering Geology,2018,26(4):905-914(in Chinese))
[8]牛亚强,王旭,廖孟柯,等.冻结改良黄土三轴强度和变形特性试验研究[J].岩土工程学报,2016,38(增2):198-203(Niu Yaqiang,Wang Xu,Liao Mengke,et al.Experimental study on triaxial strength and deformation characteristics of frozen-improved loess[J].Chinese Journal of Geotechnical Engineering,2016,38(S2):198-203(in Chinese))
[9]Zhao X D,Zhou G Q,Chen G Z.Triaxial compression deformation for artificial frozen clay with thermal gradient[J].Cold Regions Science and Technology,2011,67(3):171-177
[10]仇文革,孙兵.冻土三轴冻胀应力-应变试验方法研究[J].冰川冻土,2010,32(1):116-120(Qiu Wenge,Sun Bing.Study of the experiment method for triaxial frost heaving constitutive relations of frozen soil[J].Journal of Glaciology and Geocryology,2010,32(1):116-120(in Chinese))
[11]马巍,吴紫汪,常小晓.固结过程对冻土应力-应变特性的影响[J].岩土力学,2000,21(3):198-200,221(Ma Wei,Wu Ziwang,Chang Xiaoxiao.Effects of consolidation process on stress-strain characters of tjaeles[J].Rock and Soil Mechanics,2000,21(3):198-200,221(in Chinese))
[12]Ma W,Chang X X.Analyses of strength and deformation of an artificially frozen soil wall in underground engineering[J].Cold Regions Science and Technology,2002,34(1):11-17
[13]王衍森,贾锦波,冷阳光.长时高压K0固结再冻结黏土的卸围压强度特性[J].岩土工程学报,2017,39(6):1636-1644(Wang Yansen,Jia Jinbo,Leng Yangguang.Strength properties of unloading confining pressure of long-term K0-consolidated artifical frozen clay under high pressure[J].Chinese Journal of Geotechnical Engineering,2017,39(6):1636-1644(in Chinese))
[14]孙星亮,汪稔,胡明鉴.冻土三轴剪切过程中细观损伤演化CT动态试验[J].岩土力学,2005,26(8):1298-1302,1311(Sun Xingliang,Wang Ren,Hu Mingjian.A CT-timely experimental study on meso-scopic structural damage development of frozen soil under triaxial shearing[J].Rock and Soil Mechanics,2005,26(8):1298-1302,1311(in Chinese))
[15]孙星亮,汪稔,胡明鉴.三轴剪切条件下冻结粉质黏土变形特性的细观机理分析[J].固体力学学报,2005,26(1):62-66(Sun Xingliang,Wang Ren,Hu Mingjian.Meso-scopic mechanism analysis of deformation properties of frozen silty clay under triaxtal shear[J].Chinese Journal of Solid Mechanics,2005,26(1):62-66(in Chinese))
[16]张德,刘恩龙,刘星炎,等.冻土二元介质模型探讨-以-6℃冻结粉土为例[J].岩土工程学报,2018,40(1):82-90(Zhang De,Liu Enlong,Liu Xingyan,et al.Investigation on binary medium model taking frozen silt soils under-6℃for example[J].Chinese Journal of Geotechnical Engineering,2018,40(1):82-90(in Chinese))
[17]李栋伟,陈军浩,周艳.复杂应力路径人工冻土三轴剪切试验及本构模型[J].煤炭学报,2016,41(增):407-411(Li Dongwei,Chen Junhao,Zhou Yan.Elastic-plastic constitutive model of artificial frozen soil based on cascade-correlation artificial neural network[J].Journal of China coal society,2016,41(S2):407-411(in Chinese))
[18]李清泽,赖远明,徐湘田,等.高温冻土三轴强度分布及损伤统计本构模型[J].冰川冻土,2010,32(6):1234-1241(Li Qingze,Lai Yuanming,Xu Xiangtian,et al.Triaxial strength distribution of warm frozen soil and its damage statistical constitutive model[J].Journal of Glaciology and Geocryology,2010,32(6):1234-1241(in Chinese))
[19]孙谷雨,杨平,刘贯荣.南京地区冻结粉质黏土邓肯-张模型参数试验研究[J].岩石力学与工程学报,2014,33(增1):2989-2995(Sun Guyu,Yang Ping,Liu Guanrong.Experimental test on constitutive relationship of Nanjing frozen silty clay considering DUNCAN-CHANG model[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(S1):2989-2995(in Chinese))
[20]杨爱武,雷超炜,刘琦,等.考虑应力路径影响的吹填土结构性特征研究[J].工程地质学报,2016,24(6):1199-1206(Yang Aiwu,Lei Chaowei,Liu Qi,et al.Study on structure characteristics considering stress paths of dredger fill[J].Journal of Engineering Geology,2016,24(6):1199-1206(in Chinese))
[21]江汪洋.冻结粉质黏土强度特性与本构模型研究[D].南京:南京林业大学,2017(Jiang Wangyang.Study on strength characteristics and constitutive model of frozen silty clay[D].Nanjing:Nanjing Forestry University,2017(in Chinese))
[22]李威,庄建琦,王颖.饱和重塑黄土抗剪强度影响因素的试验研究[J].工程地质学报,2018,26(3):626-632(Li Wei,Zhuang Jianqi,Wang Yin.Experimental study on influencing factors of shear strength of saturated remolded loess[J].Journal of Engineering Geology,2018,26(3):626-632(in Chinese))
[23]汪洪星,杨春和,陈锋,等.软土抗剪强度指标随固结度变化规律分析[J].岩土力学,2014,35(增1):106-112(Wang Hongxing,Yang Chunhe,Chen Feng,et al.Analysis of changing rule of shear strength indexes of soft soil with consolidation degree[J].Rock and Soil Mechanics,2014,35(S1):106-112(in Chinese))
[2]杜海民,马巍,张淑娟,等.三轴循环加卸载条件下高含冰冻结砂土变形特性试验研究[J].岩土力学,2017,38(6):1675-1681(Du Haimin,Ma Wei,Zhang Shujuan,et al.Experimental investigation on deformation characteristics of ice-rich frozen silty sands under triax[J].Rock and Soil Mechanics,2017,38(6):1675-1681(in Chinese))
[3]Yang Y G,Lai Y M,Chang X X.Laboratory and theoretical investigations on the deformation and strength behaviors of artificial frozen soil[J].Cold Regions Science and Technology,2010,64:39-45
[4]孙钦杰,李栋伟,王伸远.人工冻结含盐砂土三轴剪切试验研究[J].煤炭技术,2015,34(4):105-107(Sun Qinjie,Li Dongwei,Wang Shenyuan.Test on triaxial shear of artificial frozen saline sand[J].Journal of China coal society,2015,34(4):105-107(in Chinese))
[5]赖远明,程红彬,高志华,等.冻结砂土的应力-应变关系及非线性莫尔强度准则[J].岩石力学与工程学报,2007,26(8):1612-1617(Lai Yuanming,Cheng Hongbing,Gao Zhihua,et al.Stress-strain relationships and nonliner mohr strength criterion of frozen sand clay[J].Chinese Journal of Rock Mechanics and Engineering,2007,26(8):1612-1617(in Chinese))
[6]常小晓,马巍,王大雁.高围压下冻结粘土的抗压强度试验研究[J].冰川冻土,2007,29(4):636-639(Chang Xiaoxiao,Ma Wei,Wang Dayan.Study on the strength of frozen clay at high confining pressure[J].Journal of Glaciology and Geocryology,2007,29(4):636-639(in Chinese))
[7]李瑞宽,吴志坚,梁庆国,等.考虑微结构特征的黄土动力特性影响因素研究[J].工程地质学报,2018,26(4):905-914(Li Ruikuan,Wu Zhijian,Liang Qingguo,et al.Influence factors of dynamic characteristics of loess considering the microstructure properties[J].Journal of Engineering Geology,2018,26(4):905-914(in Chinese))
[8]牛亚强,王旭,廖孟柯,等.冻结改良黄土三轴强度和变形特性试验研究[J].岩土工程学报,2016,38(增2):198-203(Niu Yaqiang,Wang Xu,Liao Mengke,et al.Experimental study on triaxial strength and deformation characteristics of frozen-improved loess[J].Chinese Journal of Geotechnical Engineering,2016,38(S2):198-203(in Chinese))
[9]Zhao X D,Zhou G Q,Chen G Z.Triaxial compression deformation for artificial frozen clay with thermal gradient[J].Cold Regions Science and Technology,2011,67(3):171-177
[10]仇文革,孙兵.冻土三轴冻胀应力-应变试验方法研究[J].冰川冻土,2010,32(1):116-120(Qiu Wenge,Sun Bing.Study of the experiment method for triaxial frost heaving constitutive relations of frozen soil[J].Journal of Glaciology and Geocryology,2010,32(1):116-120(in Chinese))
[11]马巍,吴紫汪,常小晓.固结过程对冻土应力-应变特性的影响[J].岩土力学,2000,21(3):198-200,221(Ma Wei,Wu Ziwang,Chang Xiaoxiao.Effects of consolidation process on stress-strain characters of tjaeles[J].Rock and Soil Mechanics,2000,21(3):198-200,221(in Chinese))
[12]Ma W,Chang X X.Analyses of strength and deformation of an artificially frozen soil wall in underground engineering[J].Cold Regions Science and Technology,2002,34(1):11-17
[13]王衍森,贾锦波,冷阳光.长时高压K0固结再冻结黏土的卸围压强度特性[J].岩土工程学报,2017,39(6):1636-1644(Wang Yansen,Jia Jinbo,Leng Yangguang.Strength properties of unloading confining pressure of long-term K0-consolidated artifical frozen clay under high pressure[J].Chinese Journal of Geotechnical Engineering,2017,39(6):1636-1644(in Chinese))
[14]孙星亮,汪稔,胡明鉴.冻土三轴剪切过程中细观损伤演化CT动态试验[J].岩土力学,2005,26(8):1298-1302,1311(Sun Xingliang,Wang Ren,Hu Mingjian.A CT-timely experimental study on meso-scopic structural damage development of frozen soil under triaxial shearing[J].Rock and Soil Mechanics,2005,26(8):1298-1302,1311(in Chinese))
[15]孙星亮,汪稔,胡明鉴.三轴剪切条件下冻结粉质黏土变形特性的细观机理分析[J].固体力学学报,2005,26(1):62-66(Sun Xingliang,Wang Ren,Hu Mingjian.Meso-scopic mechanism analysis of deformation properties of frozen silty clay under triaxtal shear[J].Chinese Journal of Solid Mechanics,2005,26(1):62-66(in Chinese))
[16]张德,刘恩龙,刘星炎,等.冻土二元介质模型探讨-以-6℃冻结粉土为例[J].岩土工程学报,2018,40(1):82-90(Zhang De,Liu Enlong,Liu Xingyan,et al.Investigation on binary medium model taking frozen silt soils under-6℃for example[J].Chinese Journal of Geotechnical Engineering,2018,40(1):82-90(in Chinese))
[17]李栋伟,陈军浩,周艳.复杂应力路径人工冻土三轴剪切试验及本构模型[J].煤炭学报,2016,41(增):407-411(Li Dongwei,Chen Junhao,Zhou Yan.Elastic-plastic constitutive model of artificial frozen soil based on cascade-correlation artificial neural network[J].Journal of China coal society,2016,41(S2):407-411(in Chinese))
[18]李清泽,赖远明,徐湘田,等.高温冻土三轴强度分布及损伤统计本构模型[J].冰川冻土,2010,32(6):1234-1241(Li Qingze,Lai Yuanming,Xu Xiangtian,et al.Triaxial strength distribution of warm frozen soil and its damage statistical constitutive model[J].Journal of Glaciology and Geocryology,2010,32(6):1234-1241(in Chinese))
[19]孙谷雨,杨平,刘贯荣.南京地区冻结粉质黏土邓肯-张模型参数试验研究[J].岩石力学与工程学报,2014,33(增1):2989-2995(Sun Guyu,Yang Ping,Liu Guanrong.Experimental test on constitutive relationship of Nanjing frozen silty clay considering DUNCAN-CHANG model[J].Chinese Journal of Rock Mechanics and Engineering,2014,33(S1):2989-2995(in Chinese))
[20]杨爱武,雷超炜,刘琦,等.考虑应力路径影响的吹填土结构性特征研究[J].工程地质学报,2016,24(6):1199-1206(Yang Aiwu,Lei Chaowei,Liu Qi,et al.Study on structure characteristics considering stress paths of dredger fill[J].Journal of Engineering Geology,2016,24(6):1199-1206(in Chinese))
[21]江汪洋.冻结粉质黏土强度特性与本构模型研究[D].南京:南京林业大学,2017(Jiang Wangyang.Study on strength characteristics and constitutive model of frozen silty clay[D].Nanjing:Nanjing Forestry University,2017(in Chinese))
[22]李威,庄建琦,王颖.饱和重塑黄土抗剪强度影响因素的试验研究[J].工程地质学报,2018,26(3):626-632(Li Wei,Zhuang Jianqi,Wang Yin.Experimental study on influencing factors of shear strength of saturated remolded loess[J].Journal of Engineering Geology,2018,26(3):626-632(in Chinese))
[23]汪洪星,杨春和,陈锋,等.软土抗剪强度指标随固结度变化规律分析[J].岩土力学,2014,35(增1):106-112(Wang Hongxing,Yang Chunhe,Chen Feng,et al.Analysis of changing rule of shear strength indexes of soft soil with consolidation degree[J].Rock and Soil Mechanics,2014,35(S1):106-112(in Chinese))