酸雨入渗对膨胀土抗剪强度的影响及微观试验研究
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摘要
为探究酸雨入渗对膨胀土抗剪强度的影响,以广西酸雨重灾区的百色原状膨胀土为研究对象,根据干湿循环影响区土体的实际状态及边界条件,模拟不同酸雨入渗情况(pH为3,5和7)进行抗剪强度试验研究,探究膨胀土抗剪强度变化规律;结合微观试验,研究其微观结构和矿物成分变化特性,揭示酸雨入渗对膨胀土的微观作用机理。研究结果表明:随酸液pH减小,试样抗剪强度不断衰减,黏聚力降幅明显,内摩擦角出现小幅度下降,且在2次干湿循环作用后,黏聚力出现最大降幅;上覆压力越小,抗剪强度衰减越明显;酸雨入渗作用下土体中游离的胶结物呈不同程度溶蚀和淋滤,微孔隙体积和数目均增大,入渗酸液pH越小,该变化趋势愈明显,微结构单元更松散,致使土体结构性减弱,抗剪强度下降。
In order to explore the effect of acid rain infiltration on the shear strength of expansive soils, the original expansive soil of Baise in the acid rain-affected areas in Guangxi was studied. According to the actual state and boundary conditions of soils in the dry-wet cycle affected area, the different conditions of acid rains infiltration were simulated pH=3, 5, 7) to investigate the evolution law of shear strength of expansive soils. The shear strength tests were conducted under different acid rain infiltration conditions to explore the changing law of shear strength of expansive soils.Microscopic tests were also carried out to clarify the changes in microstructure and mineral composition, and to reveal the mechanism of microscopic action of acid rain infiltration on expansive soils. The results show that with the decrease of pH of acid solution, the shear strength of the sample decreases continuously, and the cohesion force decreases sharply;the internal friction angle decreases slightly, and the maximum drop occurs after 2 times of dry-wet cycles. The reduction of the overburden load makes the attenuation of the shear strength more obvious. The free colloidal minerals in the soil exhibits different degrees of dissolution and leaching under the action of acid rain infiltration, the size and number of micropores increase, and the micro-structure units are looser, which leads to the weakening of soil structure and the decrease of shear strength.
In order to explore the effect of acid rain infiltration on the shear strength of expansive soils, the original expansive soil of Baise in the acid rain-affected areas in Guangxi was studied. According to the actual state and boundary conditions of soils in the dry-wet cycle affected area, the different conditions of acid rains infiltration were simulated pH=3, 5, 7) to investigate the evolution law of shear strength of expansive soils. The shear strength tests were conducted under different acid rain infiltration conditions to explore the changing law of shear strength of expansive soils.Microscopic tests were also carried out to clarify the changes in microstructure and mineral composition, and to reveal the mechanism of microscopic action of acid rain infiltration on expansive soils. The results show that with the decrease of pH of acid solution, the shear strength of the sample decreases continuously, and the cohesion force decreases sharply;the internal friction angle decreases slightly, and the maximum drop occurs after 2 times of dry-wet cycles. The reduction of the overburden load makes the attenuation of the shear strength more obvious. The free colloidal minerals in the soil exhibits different degrees of dissolution and leaching under the action of acid rain infiltration, the size and number of micropores increase, and the micro-structure units are looser, which leads to the weakening of soil structure and the decrease of shear strength.
引文
[1]汤文,姚志宾,李邵军,等.水化学作用对滑坡滑带土的物理力学特性影响试验研究[J].岩土力学,2016,37(10):2885-2892.TANG Wen,YAO Zhibin,LI Shaojun,et al.Effect of pore water chemistry on physical and mechanical properties of sliding-zone soil:an experimental study[J].Rock and Soil Mechanics,2016,37(10):2885-2892.
[2]JABOYEDOFF M,BAILLIFARD F,BARDOU E,et al.The effect of weathering on Alpine rock instability[J].Quarterly Journal of Engineering Geology&Hydrogeology,2004,37(2):95-103.
[3]韩铁林,师俊平,陈蕴生.干湿循环和化学腐蚀共同作用下单裂隙非贯通试样力学特征的试验研究[J].水利学报,2016,47(12):1566-1576.HAN Tielin,SHI Junping,CHEN Yunsheng.Laboratory study on mechanical behaviors of the single-intermittent cracked masses under the combined action of water chemical corrosion and dry-wet cycles[J].Journal of Hydraulic Engineering,2016,47(12):1566-1576.
[4]韩铁林,师俊平,陈蕴生.砂岩在化学腐蚀和冻融循环共同作用下力学特征劣化的试验研究[J].水利学报,2016,47(5):644-655.HAN Tielin,SHI Junping,CHEN Yunsheng.Laboratory investigations on the mechanical properties degradation of sandstone under the combined action between water chemical corrosion and freezing and thawing cycles[J].Journal of Hydraulic Engineering,2016,47(5):644-655.
[5]刘新荣,袁文,傅晏,等.酸碱环境干湿循环作用下砂岩抗剪强度劣化规律研究[J].岩土工程学报,2017,39(12):2320-2326.LIU Xinrong,YUAN Wen,FU Yan,et al.Deterioration rules of shear strength in sandstones under wetting and drying cycles in acid and alkali environment[J].Chinese Journal of Geotechnical Engineering,2017,39(12):2320-2326.
[6]刘新荣,袁文,傅晏,等.化学溶液和干湿循环作用下砂岩抗剪强度劣化试验及化学热力学分析[J].岩石力学与工程学报,2016,35(12):2534-2541.LIU Xinrong,YUAN Wen,FU Yan,et al.Tests on shear strength deterioration of sandstone under the action of chemical solution and drying-wetting cycles and analysis of chemical thermodynamics[J].Journal of Rock Mechanics and Geotechnical Engineering,2016,35(12):2534-2541.
[7]PRASAD C R V,REDDY P H P,MURTHY V R,et al.Swelling characteristics of soils subjected to acid contamination[J].Soils&Foundations,2017,58(1):110-121.
[8]HARI P R P,CHAVALI R V P,PILLAI R.Swelling of natural soil subjected to acidic and alkaline contamination[J].Periodica Polytechnica Civil Engineering,2017,61(3):611-620.
[9]GRATCHEV I,TOWHATA I.Stress-strain characteristics of two natural soils subjected to long-term acidic contamination[J].Soils&Foundations,2013,53(3):469-476.
[10]顾剑云,程圣国,杨云华,等.酸雨对滑坡土体抗剪强度参数影响试验研究[J].水利水电技术,2011,42(10):36-39.GU Jianyun,CHENG Shengguo,YANG Yunhua,et al.Experimental study on impact from acid rain on parameter of shear strength of landslide soil body[J].Water Resources and Hydropower Engineering,2011,42(10):36-39.
[11]赵宇,崔鹏,胡良博.黏土抗剪强度演化与酸雨引发滑坡的关系:以三峡库区滑坡为例[J].岩石力学与工程学报,2009,28(3):576-582.ZHAO Yu,CUI Peng,HU Liangbo.Relation between evolution of clay shear strength and landslide induced by acid rain-taking landslides in Three Gorges Reservoir area for Example[J].Journal of Rock Mechanics and Geotechnical Engineering,2009,28(3):576-582.
[12]SHUZUI H.Process of slip-surface development and formation of slip-surface clay in landslides in Tertiary volcanic rocks,Japan[J].Engineering Geology,2001,61(4):199-220.
[13]魏伟.酸性环境下重塑膨胀土的胀缩性和抗剪强度研究[D].桂林:桂林理工大学土木与建筑工程学院,2016:37-38.WEI Wei.Research on swelling-shrinkage and shear strength of disturbed expansive soil under acidic environment[D].Guilin:Guilin University of Technology.College of Civil&Architecture Engineering,2016:37-38.
[14]孙平安,李秀存,于奭,等.酸雨溶蚀碳酸盐岩的源汇效应分析:以广西典型岩溶区为例[J].中国岩溶,2017,36(1):101-108.SUN Pingan,LI Xiucun,YU Shi,et al.Study on source-sink effect in the process of carbonate rock dissolved by acid rain:an example of typical karst regions in Guangxi[J].Carsologica Sinic,2017,36(1):101-108.
[15]CHENG A Z,WEI H H,TAN F.Analysis of the temporal-spatial distribution and seasonal variation of the acid rain in Guangxi Province[J].Meteorological and Environmental Research,2010,1(1):62-65.
[16]中华人民共和国环境保护部.中国环境状况公报[R].北京:中华人民共和国环境保护部,2012:25-26.Environmental Protection Department of the People’s Republic of China.China environmental state bulletin[R].Beijing:Environmental Protection Department of the People’s Republic of China,2012:25-26.
[17]XIAO Jie,YANG Heping,ZHANG Junhui,et al.Surficial failure of expansive soil cutting slope and its flexible support treatment technology[J].Advances in Civil Engineering,2018,2018:1-13.
[18]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.YANG Heping,WANG Xingzheng,XIAO Jie.Influence of wetting-drying cycles on strength characteristics of Nanning expansive soils[J].Chinese Journal of Geotechnical Engineering,2014,36(5):949-954.
[19]刘剑,崔鹏.水土化学作用对土体黏聚力的影响--以蒙脱石-石英砂重塑土为例[J].岩土力学,2017,38(2):419-427.LIU Jian,CUI Peng.Influence of water-soil chemical interaction on cohesive force:a case study of montmorillonite-quartz remolded soil[J].Rock and Soil Mechanics,2017,38(2):419-427.
[20]华东水利学院土力学教研室.土工原理与计算:上册[M].北京:水利出版社,1980:1-17.Department of Soil Mechanics,East China Institute of Water Resources.Geotechnical principles and calculations:the first volume[M].Beijing:Water Conservancy Press,1980:1-17.
[21]刘华强,殷宗泽.裂缝对膨胀土抗剪强度指标影响的试验研究[J].岩土力学,2010,31(3):727-731.LIU Huaqiang,YIN Zongze.Test study of influence of crack evolution on strength parameters of expansive soil[J].Rock and Soil Mechanics,2010,31(3):727-731.
[22]杨和平,唐咸远,王兴正,等.有荷干湿循环条件下不同膨胀土抗剪强度基本特性[J].岩土力学,2018,39(7):2311-2317.YANG Heping,TANG Xianyuan,WANG Xingzheng,et al.Basic shear strength properties of expansive soils under wet-dry cycles with loading[J].Rock and Soil Mechanics,2018,39(7):2311-2317.
[23]肖杰,杨和平,李晗峰,等.低应力条件下不同密度的南宁膨胀土抗剪强度试验[J].中国公路学报,2013,26(6):15-21.XIAO Jie,YANG Heping,LI Hanfeng,et al.Shear strength test of Nanning expansive soil with various dry densities and low stresses[J].China Journal of Highway and Transport,2013,26(6):15-21.
[24]廖世文.膨胀土与铁路工程[M].北京:中国铁道出版社,1984:101-111.LIAO Shiwen.Expansive soil and railway engineering[M].Beijing:China Railway Publishing House,1984:101-111.
[25]罗鸿禧,周芳琴.郧县胀缩土的矿物成分及微观结构的研究[J].工程勘察,1981,9(5):37-40.LUO Hongxi,ZHOU Fangqin.Study on mineral composition and microstructure of Yunxian expansion and contraction soil[J].Engineering Survey,1981,9(5):37-40.
[26]WANG Y H,SIU W K.Structure characteristics and mechanical properties of kaolinite soils.I.surface charges and structural characterizations[J].Canadian Geotechnical Journal,2006,43(6):587-600.
[2]JABOYEDOFF M,BAILLIFARD F,BARDOU E,et al.The effect of weathering on Alpine rock instability[J].Quarterly Journal of Engineering Geology&Hydrogeology,2004,37(2):95-103.
[3]韩铁林,师俊平,陈蕴生.干湿循环和化学腐蚀共同作用下单裂隙非贯通试样力学特征的试验研究[J].水利学报,2016,47(12):1566-1576.HAN Tielin,SHI Junping,CHEN Yunsheng.Laboratory study on mechanical behaviors of the single-intermittent cracked masses under the combined action of water chemical corrosion and dry-wet cycles[J].Journal of Hydraulic Engineering,2016,47(12):1566-1576.
[4]韩铁林,师俊平,陈蕴生.砂岩在化学腐蚀和冻融循环共同作用下力学特征劣化的试验研究[J].水利学报,2016,47(5):644-655.HAN Tielin,SHI Junping,CHEN Yunsheng.Laboratory investigations on the mechanical properties degradation of sandstone under the combined action between water chemical corrosion and freezing and thawing cycles[J].Journal of Hydraulic Engineering,2016,47(5):644-655.
[5]刘新荣,袁文,傅晏,等.酸碱环境干湿循环作用下砂岩抗剪强度劣化规律研究[J].岩土工程学报,2017,39(12):2320-2326.LIU Xinrong,YUAN Wen,FU Yan,et al.Deterioration rules of shear strength in sandstones under wetting and drying cycles in acid and alkali environment[J].Chinese Journal of Geotechnical Engineering,2017,39(12):2320-2326.
[6]刘新荣,袁文,傅晏,等.化学溶液和干湿循环作用下砂岩抗剪强度劣化试验及化学热力学分析[J].岩石力学与工程学报,2016,35(12):2534-2541.LIU Xinrong,YUAN Wen,FU Yan,et al.Tests on shear strength deterioration of sandstone under the action of chemical solution and drying-wetting cycles and analysis of chemical thermodynamics[J].Journal of Rock Mechanics and Geotechnical Engineering,2016,35(12):2534-2541.
[7]PRASAD C R V,REDDY P H P,MURTHY V R,et al.Swelling characteristics of soils subjected to acid contamination[J].Soils&Foundations,2017,58(1):110-121.
[8]HARI P R P,CHAVALI R V P,PILLAI R.Swelling of natural soil subjected to acidic and alkaline contamination[J].Periodica Polytechnica Civil Engineering,2017,61(3):611-620.
[9]GRATCHEV I,TOWHATA I.Stress-strain characteristics of two natural soils subjected to long-term acidic contamination[J].Soils&Foundations,2013,53(3):469-476.
[10]顾剑云,程圣国,杨云华,等.酸雨对滑坡土体抗剪强度参数影响试验研究[J].水利水电技术,2011,42(10):36-39.GU Jianyun,CHENG Shengguo,YANG Yunhua,et al.Experimental study on impact from acid rain on parameter of shear strength of landslide soil body[J].Water Resources and Hydropower Engineering,2011,42(10):36-39.
[11]赵宇,崔鹏,胡良博.黏土抗剪强度演化与酸雨引发滑坡的关系:以三峡库区滑坡为例[J].岩石力学与工程学报,2009,28(3):576-582.ZHAO Yu,CUI Peng,HU Liangbo.Relation between evolution of clay shear strength and landslide induced by acid rain-taking landslides in Three Gorges Reservoir area for Example[J].Journal of Rock Mechanics and Geotechnical Engineering,2009,28(3):576-582.
[12]SHUZUI H.Process of slip-surface development and formation of slip-surface clay in landslides in Tertiary volcanic rocks,Japan[J].Engineering Geology,2001,61(4):199-220.
[13]魏伟.酸性环境下重塑膨胀土的胀缩性和抗剪强度研究[D].桂林:桂林理工大学土木与建筑工程学院,2016:37-38.WEI Wei.Research on swelling-shrinkage and shear strength of disturbed expansive soil under acidic environment[D].Guilin:Guilin University of Technology.College of Civil&Architecture Engineering,2016:37-38.
[14]孙平安,李秀存,于奭,等.酸雨溶蚀碳酸盐岩的源汇效应分析:以广西典型岩溶区为例[J].中国岩溶,2017,36(1):101-108.SUN Pingan,LI Xiucun,YU Shi,et al.Study on source-sink effect in the process of carbonate rock dissolved by acid rain:an example of typical karst regions in Guangxi[J].Carsologica Sinic,2017,36(1):101-108.
[15]CHENG A Z,WEI H H,TAN F.Analysis of the temporal-spatial distribution and seasonal variation of the acid rain in Guangxi Province[J].Meteorological and Environmental Research,2010,1(1):62-65.
[16]中华人民共和国环境保护部.中国环境状况公报[R].北京:中华人民共和国环境保护部,2012:25-26.Environmental Protection Department of the People’s Republic of China.China environmental state bulletin[R].Beijing:Environmental Protection Department of the People’s Republic of China,2012:25-26.
[17]XIAO Jie,YANG Heping,ZHANG Junhui,et al.Surficial failure of expansive soil cutting slope and its flexible support treatment technology[J].Advances in Civil Engineering,2018,2018:1-13.
[18]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.YANG Heping,WANG Xingzheng,XIAO Jie.Influence of wetting-drying cycles on strength characteristics of Nanning expansive soils[J].Chinese Journal of Geotechnical Engineering,2014,36(5):949-954.
[19]刘剑,崔鹏.水土化学作用对土体黏聚力的影响--以蒙脱石-石英砂重塑土为例[J].岩土力学,2017,38(2):419-427.LIU Jian,CUI Peng.Influence of water-soil chemical interaction on cohesive force:a case study of montmorillonite-quartz remolded soil[J].Rock and Soil Mechanics,2017,38(2):419-427.
[20]华东水利学院土力学教研室.土工原理与计算:上册[M].北京:水利出版社,1980:1-17.Department of Soil Mechanics,East China Institute of Water Resources.Geotechnical principles and calculations:the first volume[M].Beijing:Water Conservancy Press,1980:1-17.
[21]刘华强,殷宗泽.裂缝对膨胀土抗剪强度指标影响的试验研究[J].岩土力学,2010,31(3):727-731.LIU Huaqiang,YIN Zongze.Test study of influence of crack evolution on strength parameters of expansive soil[J].Rock and Soil Mechanics,2010,31(3):727-731.
[22]杨和平,唐咸远,王兴正,等.有荷干湿循环条件下不同膨胀土抗剪强度基本特性[J].岩土力学,2018,39(7):2311-2317.YANG Heping,TANG Xianyuan,WANG Xingzheng,et al.Basic shear strength properties of expansive soils under wet-dry cycles with loading[J].Rock and Soil Mechanics,2018,39(7):2311-2317.
[23]肖杰,杨和平,李晗峰,等.低应力条件下不同密度的南宁膨胀土抗剪强度试验[J].中国公路学报,2013,26(6):15-21.XIAO Jie,YANG Heping,LI Hanfeng,et al.Shear strength test of Nanning expansive soil with various dry densities and low stresses[J].China Journal of Highway and Transport,2013,26(6):15-21.
[24]廖世文.膨胀土与铁路工程[M].北京:中国铁道出版社,1984:101-111.LIAO Shiwen.Expansive soil and railway engineering[M].Beijing:China Railway Publishing House,1984:101-111.
[25]罗鸿禧,周芳琴.郧县胀缩土的矿物成分及微观结构的研究[J].工程勘察,1981,9(5):37-40.LUO Hongxi,ZHOU Fangqin.Study on mineral composition and microstructure of Yunxian expansion and contraction soil[J].Engineering Survey,1981,9(5):37-40.
[26]WANG Y H,SIU W K.Structure characteristics and mechanical properties of kaolinite soils.I.surface charges and structural characterizations[J].Canadian Geotechnical Journal,2006,43(6):587-600.