制样方法对非饱和压实黄土强度变化影响的试验研究
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摘要
为研究不同制样方法对非饱和压实黄土抗剪强度指标的影响规律,进行不同干密度压实土在预湿及加湿两种制样方法下的剪切试验研究。结果表明:预湿制样试验中,存在一个临界含水率影响着试验黄土的黏聚力、摩擦角,当试样的含水率低于临界含水率时,抗剪强度随含水率增加而提高,而当含水率高于临界含水率时,抗剪强度随含水率的增加而降低;抗剪强度指标总体随试样干密度的增大而增大。加湿制样试验中,随着试样含水率的增加,黏聚力连续降低,摩擦角随含水率的增加先提高后降低,对比预湿试样而言,含水率对摩擦角的折减程度降低。可以看出制样方法对非饱和压实黄土黏聚力的影响特征比较突出,当含水率低于临界含水率时加湿试样的黏聚力比预湿试样大,而当含水率高于临界含水率时预湿试样的黏聚力较高,认为加湿试样存在类似"木桶效应",而预湿试样则与试样整体水平有关。研究结果对于进一步加深非饱和黄土抗剪强度指标的适用性研究具有一定参考价值。
The shear tests of compacted loess with different dry densities were conducted using two different sample preparation methods(pre-humidification and humidification) to study their influence on the shear strength index of the unsaturated compacted loess. The results of this study exhibit the presence of critical moisture content that affects the cohesion and friction angle of the loess in the pre-wetting sample preparation test. When the moisture content of the sample was lower than the critical moisture content, the shear strength increased with increasing moisture content; however, when the moisture content of the sample was higher than the critical moisture content, the shear strength decreased with increasing moisture content. Further, the shear strength index generally increased with the increasing dry density of the sample. During the wetting sample preparation test, the cohesion continuously decreased with increasing moisture content, and the friction angle initially increased and subsequently decreased with increasing moisture content. When compared with the pre-wetting sample, the reduction degree of the moisture content to the friction angle decreased. It can be observed that the sample preparation method significantly influences the cohesion of the unsaturated compacted loess. When the moisture content of the sample was lower than the critical moisture content, the cohesion of the wetting sample was larger than that of the pre-wetting sample; however, when the moisture content of the sample is higher than the critical moisture content, the cohesion of the pre-wetting sample is larger. It can be considered that the wetting sample exhibits a similar "barrel effect"; the pre-wetting sample is related to the overall level of the sample. The research results exhibit a certain reference value for further applicability of the shear strength index of the unsaturated loess.
The shear tests of compacted loess with different dry densities were conducted using two different sample preparation methods(pre-humidification and humidification) to study their influence on the shear strength index of the unsaturated compacted loess. The results of this study exhibit the presence of critical moisture content that affects the cohesion and friction angle of the loess in the pre-wetting sample preparation test. When the moisture content of the sample was lower than the critical moisture content, the shear strength increased with increasing moisture content; however, when the moisture content of the sample was higher than the critical moisture content, the shear strength decreased with increasing moisture content. Further, the shear strength index generally increased with the increasing dry density of the sample. During the wetting sample preparation test, the cohesion continuously decreased with increasing moisture content, and the friction angle initially increased and subsequently decreased with increasing moisture content. When compared with the pre-wetting sample, the reduction degree of the moisture content to the friction angle decreased. It can be observed that the sample preparation method significantly influences the cohesion of the unsaturated compacted loess. When the moisture content of the sample was lower than the critical moisture content, the cohesion of the wetting sample was larger than that of the pre-wetting sample; however, when the moisture content of the sample is higher than the critical moisture content, the cohesion of the pre-wetting sample is larger. It can be considered that the wetting sample exhibits a similar "barrel effect"; the pre-wetting sample is related to the overall level of the sample. The research results exhibit a certain reference value for further applicability of the shear strength index of the unsaturated loess.
引文
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[4] 朱彦鹏,栗慧珺,杨校辉,等.黄土改良红砂岩的试验及路用性能研究[J].水利与建筑工程学报,2017,15(6):12-15.ZHU Yanpeng,LI Huijun,YANG Xiaohui,et al.Experimental Study on Mixing Red Sandstone with Loess and Its Performance[J].Journal of Water Resources and Architectural Engineering,2017,15(6):12-15.
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[6] 黄琨,万军伟,陈刚,等.非饱和土的抗剪强度与含水率关系的试验研究[J].岩土力学,2012,33(9):2600-2604.HUANG Kun,WAN Junwei,CHEN Gang,et al.Testing Study of Relationship between Water Content and Shear Strength of Unsaturated Soils[J].Rock and Soil Mechanics,2012,33(9):2600-2604.
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[8] 黄泽,张沛然,肖丁,等.重塑黄土抗剪强度试验研究[J].四川建筑科学研究,2015,41(4):36-39.HUANG Ze,ZHANG Peiran,XIAO Ding,et al.Experimental Study on Shear Strength of Remolded Loess[J].Sichuan Building Science,2015,41(4):36-39.
[9] 李振,邢义川,周俊.膨胀土两种不同条件下抗剪强度比较[J].水力发电学报,2009,28(1):165-170.LI Zhen,XING Yichuan,ZHOU Jun.Comparison with Shear Strength of the Expansive Soil under Two Different Conditions[J].Journal of Hydroelectric Engineering,2009,28(1):165-170.
[10] 郑剑锋,马巍,赵淑萍,等.重塑土室内制样技术对比研究[J].冰川冻土,2008,30(3):494-500.ZHENG Jianfeng,MA Wei,ZHAO Shuping,et al.Development of the Specimen-preparing Technique for Remoulded Soil Samples[J].Journal of Glaciology and Geocryology,2008,30(3):494-500.
[11] 胡海军,蒋明镜,赵涛,等.制样方法对重塑黄土单轴抗拉强度影响的初探[J].岩土力学,2009,30(增刊2):205-208.HU Haijun,JIANG Mingjing,ZHAO Tao,et al.Effects of Specimen-preparing Methods on Tensile Strength of Remolded Loess[J].Rock and Soil Mechanics,2009,30(Supp2):205-208.
[12] 吕海波,董均贵,吴畏.不同成样方式下含水率与非饱和膨胀土抗剪强度的关系[J].河南理工大学学报(自然科学版),2018,37(4):123-129.Lü Haibo,DONG Jungui,WU Wei.Relations between Water Content and Shear Strength of Unsaturated Expansive Soils Based on Different Sample-preparing Method[J].Journal of Henan Polytechnic University (Natural Science),2018,37(4):123-129.
[13] 闫芙蓉,胡雪源,崔芳.非饱和黄土抗剪强度特性试验研究[J].水利与建筑工程学报,2017,15(5):100-104.YAN Furong,HU Xueyuan,CUI Fang.Experimental Study on Shear Strength Characteristics of Unsaturated Loess[J].Journal of Water Resources and Architectural Engineering,2017,15(5):100-104.
[14] 申春妮,方祥位,陈正汉.Q2黄土的非饱和直剪试验研究[J].地下空间与工程学报,2010,6(4):724-728.SHEN Chunni,FANG Xiangwei,CHEN Zhenghan.The Unsaturated Direct Shear Tests of Q2 Loess[J].Chinese Journal of Underground Space and Engineering,2010,6(4):724-728.
[15] 梁庆国,房军,张晋东,等.兰州轨道交通扰动场地黄土浸水试验研究[J].地质力学学报,2018,24(6):803-812.LIANG Qingguo,FANG Jun,ZHANG Jindong,et al.In-situ Soaking Test on the Disturbed Loess Site at Lanzhou Metro,Gansu Province,China[J].Journal of Geomechanics,2018,24(6):803-812.
[16] 赵志强.含水量对黄土强度特性影响的研究[D].郑州:华北水利水电大学,2016.ZHAO Zhiqiang.Influence of Moisture Content on Shear Strength of Loess[D].Zhengzhou:North China University of Water Resources and Electric Power,2016.
[17] 张志权,井彦林,孔德泉.压实黄土直剪强度试验研究[J].铁道建筑,2016(12):69-71.ZHANG Zhiquan,JING Yanlin,KONG Dequan.Experimental Study on Direct Shear Strength of Compacted Loess[J].Railway Engineering,2016(12):69-71.
[18] 谢定义.试论我国黄土力学研究中的若干新趋向[J].岩土工程学报,2001,23(1):3-13.XEI Dingyi.Exploration of Some New Tendencies in Research of Loess Soil Mechanics[J].Chinese Jounal of Geotechnical Engineering,2001,23(1):3-13.
[19] 谢定义.黄土力学特性与应用研究的过去,现在与未来[J].地下空间与工程学报,1999,19(4):273-284. XEI Dingyi.Past,Present and Future of Loess Mechanical Properties and Application Research[J].Underground Space,1999,19(4):273-284.
[20] 姚志华,陈正汉.膨胀土增湿和干燥过程中的细观结构变化研究[J].水利与建筑工程学报,2009,7(3):1-4.YAO Zhihua,CHEN Zhenghan.Study on Meso-structure Changes of Expansive Soils during Wetting-Drying Cycles[J].Journal of Water Resources and Architectural Engineering,2009,7(3):1-4.
[21] 李丽,张坤,张青龙,等.干湿和冻融循环作用下黄土强度劣化特性试验研究[J].冰川冻土,2016,38(4):1142-1149.LI Li,ZHANG Kun,ZHANG Qinglong,et al.Experimental Study on the Loess Strength Degradation Characteristics under the Action of Dry-Wet and Freeze-Thaw Cycles[J].Journal of Glaciology and Geocryology,2016,38(4):1142-1149.
[22] 袁志辉.干湿循环下黄土的强度及微结构变化机理研究[D].西安:长安大学,2015.YUAN Zhihui.Research on Change Mechanism of Strength and Microstructure of Loess under Wetting-Drying Cycle[D].Xi'an:Chang'an University,2015.
[2] 郭江涛.新疆伊犁非饱和黄土的直剪性能试验研究[J].水利与建筑工程学报,2014,12(4):129-132.GUO Jiangtao.The Experimental Research of Xinjiang Yili Unsaturated Loess' Direct Shear Strength[J].Journal of Water Resources and Architectural Engineering,2014,12(4):129-132.
[3] 杨磊.黄土抗剪强度特性分析[J].水利与建筑工程学报,2010,8(3):163-165.YANG Lei.Analysis of Characteristics about Shear Strength of Loess[J].Journal of Water Resources and Architectural Engineering,2010,8(3):163-165.
[4] 朱彦鹏,栗慧珺,杨校辉,等.黄土改良红砂岩的试验及路用性能研究[J].水利与建筑工程学报,2017,15(6):12-15.ZHU Yanpeng,LI Huijun,YANG Xiaohui,et al.Experimental Study on Mixing Red Sandstone with Loess and Its Performance[J].Journal of Water Resources and Architectural Engineering,2017,15(6):12-15.
[5] 冀慧.含水量及剪切速率对黄土抗剪强度特性的影响[J].电力学报,2016,31(3):259-265.JI Hui.The Influence on Shear Strength Characteristics of Loess by Water Content and Shear Rate[J].Journal of Electric Power,2016,31(3):259-265.
[6] 黄琨,万军伟,陈刚,等.非饱和土的抗剪强度与含水率关系的试验研究[J].岩土力学,2012,33(9):2600-2604.HUANG Kun,WAN Junwei,CHEN Gang,et al.Testing Study of Relationship between Water Content and Shear Strength of Unsaturated Soils[J].Rock and Soil Mechanics,2012,33(9):2600-2604.
[7] 李文.含水率对甘肃黄土边坡抗剪强度的影响研究[D].西安:长安大学,2010.LI Wen.Study of the Water Content Effect on Shear Strength of Loess Slope in Gansu Area[D].Xi'an:Chang'an University,2010.
[8] 黄泽,张沛然,肖丁,等.重塑黄土抗剪强度试验研究[J].四川建筑科学研究,2015,41(4):36-39.HUANG Ze,ZHANG Peiran,XIAO Ding,et al.Experimental Study on Shear Strength of Remolded Loess[J].Sichuan Building Science,2015,41(4):36-39.
[9] 李振,邢义川,周俊.膨胀土两种不同条件下抗剪强度比较[J].水力发电学报,2009,28(1):165-170.LI Zhen,XING Yichuan,ZHOU Jun.Comparison with Shear Strength of the Expansive Soil under Two Different Conditions[J].Journal of Hydroelectric Engineering,2009,28(1):165-170.
[10] 郑剑锋,马巍,赵淑萍,等.重塑土室内制样技术对比研究[J].冰川冻土,2008,30(3):494-500.ZHENG Jianfeng,MA Wei,ZHAO Shuping,et al.Development of the Specimen-preparing Technique for Remoulded Soil Samples[J].Journal of Glaciology and Geocryology,2008,30(3):494-500.
[11] 胡海军,蒋明镜,赵涛,等.制样方法对重塑黄土单轴抗拉强度影响的初探[J].岩土力学,2009,30(增刊2):205-208.HU Haijun,JIANG Mingjing,ZHAO Tao,et al.Effects of Specimen-preparing Methods on Tensile Strength of Remolded Loess[J].Rock and Soil Mechanics,2009,30(Supp2):205-208.
[12] 吕海波,董均贵,吴畏.不同成样方式下含水率与非饱和膨胀土抗剪强度的关系[J].河南理工大学学报(自然科学版),2018,37(4):123-129.Lü Haibo,DONG Jungui,WU Wei.Relations between Water Content and Shear Strength of Unsaturated Expansive Soils Based on Different Sample-preparing Method[J].Journal of Henan Polytechnic University (Natural Science),2018,37(4):123-129.
[13] 闫芙蓉,胡雪源,崔芳.非饱和黄土抗剪强度特性试验研究[J].水利与建筑工程学报,2017,15(5):100-104.YAN Furong,HU Xueyuan,CUI Fang.Experimental Study on Shear Strength Characteristics of Unsaturated Loess[J].Journal of Water Resources and Architectural Engineering,2017,15(5):100-104.
[14] 申春妮,方祥位,陈正汉.Q2黄土的非饱和直剪试验研究[J].地下空间与工程学报,2010,6(4):724-728.SHEN Chunni,FANG Xiangwei,CHEN Zhenghan.The Unsaturated Direct Shear Tests of Q2 Loess[J].Chinese Journal of Underground Space and Engineering,2010,6(4):724-728.
[15] 梁庆国,房军,张晋东,等.兰州轨道交通扰动场地黄土浸水试验研究[J].地质力学学报,2018,24(6):803-812.LIANG Qingguo,FANG Jun,ZHANG Jindong,et al.In-situ Soaking Test on the Disturbed Loess Site at Lanzhou Metro,Gansu Province,China[J].Journal of Geomechanics,2018,24(6):803-812.
[16] 赵志强.含水量对黄土强度特性影响的研究[D].郑州:华北水利水电大学,2016.ZHAO Zhiqiang.Influence of Moisture Content on Shear Strength of Loess[D].Zhengzhou:North China University of Water Resources and Electric Power,2016.
[17] 张志权,井彦林,孔德泉.压实黄土直剪强度试验研究[J].铁道建筑,2016(12):69-71.ZHANG Zhiquan,JING Yanlin,KONG Dequan.Experimental Study on Direct Shear Strength of Compacted Loess[J].Railway Engineering,2016(12):69-71.
[18] 谢定义.试论我国黄土力学研究中的若干新趋向[J].岩土工程学报,2001,23(1):3-13.XEI Dingyi.Exploration of Some New Tendencies in Research of Loess Soil Mechanics[J].Chinese Jounal of Geotechnical Engineering,2001,23(1):3-13.
[19] 谢定义.黄土力学特性与应用研究的过去,现在与未来[J].地下空间与工程学报,1999,19(4):273-284. XEI Dingyi.Past,Present and Future of Loess Mechanical Properties and Application Research[J].Underground Space,1999,19(4):273-284.
[20] 姚志华,陈正汉.膨胀土增湿和干燥过程中的细观结构变化研究[J].水利与建筑工程学报,2009,7(3):1-4.YAO Zhihua,CHEN Zhenghan.Study on Meso-structure Changes of Expansive Soils during Wetting-Drying Cycles[J].Journal of Water Resources and Architectural Engineering,2009,7(3):1-4.
[21] 李丽,张坤,张青龙,等.干湿和冻融循环作用下黄土强度劣化特性试验研究[J].冰川冻土,2016,38(4):1142-1149.LI Li,ZHANG Kun,ZHANG Qinglong,et al.Experimental Study on the Loess Strength Degradation Characteristics under the Action of Dry-Wet and Freeze-Thaw Cycles[J].Journal of Glaciology and Geocryology,2016,38(4):1142-1149.
[22] 袁志辉.干湿循环下黄土的强度及微结构变化机理研究[D].西安:长安大学,2015.YUAN Zhihui.Research on Change Mechanism of Strength and Microstructure of Loess under Wetting-Drying Cycle[D].Xi'an:Chang'an University,2015.