含水量对黄土边坡稳定性的影响
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摘要
为了研究含水量变化对黄土边坡稳定性的影响,首先对兰州某黄土边坡的黄土试样进行了不同含水量下的直剪试验。试验结果表明,随着含水量的增加,黄土的抗剪强度以幂函数形式减小。但含水量对内摩擦角的影响更显著。因为黄土的粘聚力较小,其变化对抗剪强度的影响相对较小。其次,应用直剪试验结果对四个简单边坡模型进行了黄土边坡稳定性系数随含水量变化的分析。分析表明:随着含水量的增加,黄土边坡的稳定性系数以幂函数形式逐渐降低,当含水量较高时逐渐趋缓。实际上,边坡稳定性系数随含水量变化规律与抗剪强度随含水量变化规律相似。相同坡度时,边坡的高度对稳定性系数有不太大的影响,特别当黄土边坡含水量达到9%以上时,坡高对边坡稳定性系数的影响可以忽略。
In order to study the influence of water content on the stability of loess slope,first,direct shear tests on loess samples with different water content secured from a loess slope in Lanzhou with different water content were carried out. The testing results show that the shear strength of the loess decreases as a power function of water content. However,water content affects the internal friction angle of loess more significantly. Because the cohesion of loess is weak,so its change with increase of water content is relatively insignificant as far as the shear strength is concerned. Secondly,the influence of water content on factor of slope stability was studied by applying the direct shear tests results to four simple slope models. It is found that the factor of slope stability decreases as a power function of water content,but at the high water content level,the change of factor of slope stability slows gradually with further increase of water content. Actually,as water content increases,the shear strength and the factor of slope stability change in a similar way. Under the same slope angle,the height of slope has a minor effect on slope stability,however,when the water content of loess slope reaches 9% and above,the effect of slope height on factor of slope stability is negligible.
In order to study the influence of water content on the stability of loess slope,first,direct shear tests on loess samples with different water content secured from a loess slope in Lanzhou with different water content were carried out. The testing results show that the shear strength of the loess decreases as a power function of water content. However,water content affects the internal friction angle of loess more significantly. Because the cohesion of loess is weak,so its change with increase of water content is relatively insignificant as far as the shear strength is concerned. Secondly,the influence of water content on factor of slope stability was studied by applying the direct shear tests results to four simple slope models. It is found that the factor of slope stability decreases as a power function of water content,but at the high water content level,the change of factor of slope stability slows gradually with further increase of water content. Actually,as water content increases,the shear strength and the factor of slope stability change in a similar way. Under the same slope angle,the height of slope has a minor effect on slope stability,however,when the water content of loess slope reaches 9% and above,the effect of slope height on factor of slope stability is negligible.
引文
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[9] Geo-slope International Ltd. Stability Modeling with SLOPE/W 2007 Version[M]. Alberta, Canada,2008.
[2]吴玮江,叶伟林,姚正学,等.甘肃永靖黑方台4·29罗家坡黄土滑坡的特征[J].冰川冻土,2016,38(3):662-670.WU Weijiang,YE Weilin,YAO Zhengxue,et al.Characteristics of the Luojiapo loess landslides at Heifangtai,burst on April 29, 2015,in Yongjing County,Gansu Province[J]. Journal of Glaciology and Geocryology,2016,38(3):662-670.
[3]王家鼎.高速黄土滑坡的一种机理——饱和黄土蠕动液化[J].地质论评,1992,38(6):532-539.WANG Jiading. A mechanism of high-speed loess landslides:Saturated loess creeping liquefaction[J].Geological Review,1992,38(6):532-539.
[4]贾俊,朱立峰,胡炜.甘肃黑方台地区灌溉型黄土滑坡形成机理与运动学特征——以焦家崖头13号滑坡为例[J].地质通报,2013,32(12):1968-1975.JIA Jun, ZHU Lifeng, HU Wei. The formation mechanism and disaster mode of loess landslides induced by irrigation in Heifangtai,Gansu Province:A case study of the 13th landslide in Jiaojiayatou[J].Geological Bulletin of China,2013,32(12):1968-1975.
[5]尚慧,倪万魁,杜光波,等.黄土滑坡形成机理分析——以宁夏彭阳县为例[J].中国地质灾害与防治学报,2011,22(2):26-33.SHANG Hui,NI Wankui,DU Guangbo,et al. Analysis of the formation mechanism of loess landslides:Case study in Pengyang Country,Ningxia Province[J].Chinese Journal of Geological Hazard and Control,2011,22(2):26-33.
[6]宋丙辉.兰州原状Q2黄土抗剪强度的水敏感性特征研究[C]//2016年全国工程地质学术年会论文集.中国地质学会工程地质专业委员会,2016:7.SONG Binghui. Study on the water sensitivity characteristic of the shear strength of undisturbed Q2loess in Lanzhou[C]//Proceedings of the 2016National Academy of Engineering Geology Annual Conference. China Geological Association Engineering Geology Committee,2016:7.
[7]袁中夏,王兰民,严耿升.兰州黄土的土水特征曲线试验研究[J].工程勘察,2012(5):10-14.YUAN Zhongxia,WANG Lanmin,YAN Gengsheng.Study on soil-water characteristic curves of loess[J].Geotechnical Investigation&Surveying,2012(5):10-14.
[8]米海珍,李如梦,牛军贤.兰州原状黄土剪切强度特性的试验研究[J].兰州理工大学学报,2006(4):109-111.MI Haizhen,LI Rumeng,NIU Junxian. Experimental investigation of shear strength characteristics of intact loess in Lanzhou[J]. Journal of Lanzhou University of Technology,2006(4):109-111.
[9] Geo-slope International Ltd. Stability Modeling with SLOPE/W 2007 Version[M]. Alberta, Canada,2008.