液限对南阳原状膨胀土抗剪强度影响的研究
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摘要
为探讨膨胀土液限与黏粒含量的关系,以及液限对膨胀土峰值强度摩擦角和残余强度摩擦角的影响,利用电动应变控制式剪切仪和ShearTracⅡ反复直剪仪对26种原状膨胀土进行快剪试验(快剪、饱和快剪、饱和固结快剪)和反复剪试验。结果表明:膨胀土液限与黏粒含量呈良好的线性正相关关系;不同状态下试样的峰值强度大小顺序为饱和固结快剪强度>快剪强度>饱和快剪强度;随着液限增加,峰值强度的摩擦角逐渐减小,且液限对饱和快剪摩擦角的削弱作用强于对其他两者的削弱作用,当液限超过57%后,饱和快剪摩擦角略微增大,但不明显,三者摩擦角大小排序与峰值强度排序相同;低法向应力下,饱和样残余强度应力位移曲线的应变软化特性相较天然样有所减弱,峰态也逐渐减弱或消失;随着液限增加,试样残余强度摩擦角呈多项式逐渐减小趋势。
In order to study the relationship between liquid limit and clay content of expansive soil and the effect of liquid limit on the friction angle of peak strength and residual strength friction angle of expansive soil,quick shear(including quick shear,saturated quick shear,saturated and consolidated quick shear) and repeated reversal direct shear tests were conducted on 26 kinds of undisturbed soil by using electric strain controlled direct shear apparatus and ShearTrac II repeated direct shear apparatus.The results showed that:there was a good linear positive correlation between the liquid limit and clay content in expansive soil;the order of peak strength in different states of samples was that saturated and consolidated quick shear strength > quick shear strength > saturated quick shear strength.The friction angle of peak strength decreased with increase of liquid limit,and the weaking effect of liquid limit on friction angle of the saturated quick shear was much stronger than that on the other two.When the liquid limit increased to 57%,the friction angle of saturated quick shear increased slightly,but not obviously,the order of these friction angles was same as that of peak strength.Under low normal stress,the residual strength stress and displacement curve's strain softening characteristic of saturated samples was weaker than natural samples',and the state of peak also would weaken or disappear.With the increase of liquid limit,the friction angle of residual strength decreased gradually in a polynomial manner.
In order to study the relationship between liquid limit and clay content of expansive soil and the effect of liquid limit on the friction angle of peak strength and residual strength friction angle of expansive soil,quick shear(including quick shear,saturated quick shear,saturated and consolidated quick shear) and repeated reversal direct shear tests were conducted on 26 kinds of undisturbed soil by using electric strain controlled direct shear apparatus and ShearTrac II repeated direct shear apparatus.The results showed that:there was a good linear positive correlation between the liquid limit and clay content in expansive soil;the order of peak strength in different states of samples was that saturated and consolidated quick shear strength > quick shear strength > saturated quick shear strength.The friction angle of peak strength decreased with increase of liquid limit,and the weaking effect of liquid limit on friction angle of the saturated quick shear was much stronger than that on the other two.When the liquid limit increased to 57%,the friction angle of saturated quick shear increased slightly,but not obviously,the order of these friction angles was same as that of peak strength.Under low normal stress,the residual strength stress and displacement curve's strain softening characteristic of saturated samples was weaker than natural samples',and the state of peak also would weaken or disappear.With the increase of liquid limit,the friction angle of residual strength decreased gradually in a polynomial manner.
引文
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[13] LI Y R,WEN B P,AYDIN A,et al.Ring shear tests on slip zone soils of three giant landslides in the Three Gorges Project area[J].Engineering Geology,2013,154(2):106-115.
[14] 徐彬,殷宗泽,刘述丽.膨胀土强度影响因素与规律的试验研究[J].岩土力学,2011,32(1):44-50.XU B,YIN Z Z,LIU S L.Experimental study on the in-fluence factors and strength laws of expansive soil[J].Rock and Soil Mechanics,2011,32(1):44-50.
[15] SKEMPTON A W.Residual strength of clays in landslides,folded strata and the laboratory[J].Géotechnique,2015,35(1):3-18.
[16] STARK T D,CHOI H,MCCONE S.Drained Shear strength parameters for analysis of landslides[J].Journal of Geotechnical and Geoenvironmental Engineering,2005,131(5):575-588.
[17] CHANDLER R J.Recent European experience of landslides in over consolidated clays and soft rocks[C].Proc.4th Int.Symposium on Landslides .Toronto:[s.n.],1984:61-81.
[18] WESLEY L D.Residual strength of clays and correlations using Atterberg limits[J].Géotechnique,2003,54(7):503-504.
[19] LUPINI J F.The drained residual strength of cohesive soil[J].Geotechnique,1981,31(1):76-76.
[20] COLLOTTA T,CANTONI R,PAVESI U,et al.A correlation between residual friction angle,gradation and the index properties of cohesive soils[J].Geotechnique,1989,392:343-346.
[21] CEPEDA-DIAZ A F,MESRI G.Residual shear strength of clays and shales[J].Géotechnique,1986,36(2):269-274.
[22] TIWARI B.A new method for the correlation of residual shear strength of the soil with mineralogical composition[J].Journal of Geotechnical and Geoenvironmental Engineering,2005,131(9):1139-1150.
[2] 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(7):2311-2317.YANG H P,TANG X Y,WANG X Z,et al.Shear strength of expansive soils under wet-dry cycles with loading[J].Rock and Soil Mechanics,2018(7):2311-2317.
[3] 黄震,傅鹤林,韦秉旭,等.等幅干湿循环条件下膨胀土的低应力抗剪强度特征[J].四川大学学报(工程科学版),2016,48(1):70-77.HUANG Z,FU H L,WEI B X,et al.Low stress shear strength characteristics of expansive soil under constant amplitude dry wet cycle conditions[J].Journal of Sichuan University(Engineering Science Edition),2016,48(1):70-77.
[4] 徐丹,唐朝生,冷挺,等.干湿循环对非饱和膨胀土抗剪强度影响的试验研究[J].地学前缘,2018(1):286-296.XU D,TANG C S,LENG T,et al.Shear strength of unsaturated expansive soil during wetting-drying cycles[J].Earth Science Frontiers,2018(1):286-296.
[5] 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.LYU H B,DONG J G,WU W.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.
[6] 刘述丽,徐彬,殷宗泽.膨胀性对膨胀土强度影响的试验研究[J].河南科技学院学报(自然科学版),2018,46(2):72-78.LIU S L,XU B,YIN Z Z.Experimental study of expansion influencing expansive soil strength[J].Journal of Henan Institute of Science and Technology(Natural Science Edition),2018,46(2):72-78.
[7] 黄志全,吴林峰,王安明,等.基于原位剪切试验的膨胀土边坡稳定性研究[J].岩土力学,2008,29(7):1764-1768.HUANG Z Q,WU L F,WANG A M,et al.Stability analysis of expansive soil slope based on in-situ shear test[J].Rock and Soil Mechanics,2008,29(7):1764-1768.
[8] 吴珺华,杨松.干湿循环下膨胀土基质吸力测定及其对抗剪强度影响试验研究[J].岩土力学,2017,38(3):678-684.WU J H,YANG S.Experimental study of matric suction measurement and its impact on shear strength under drying-wetting cycles for expansive soils[J].Rock and Soil Mechanics,2017,38(3):678-684.
[9] 周葆春,孔令伟,马全国,等.压实膨胀土非饱和抗剪强度的湿度与密度效应[J].岩土力学,2017(s1):240-246.ZHOU B C,KONG L W,MA Q G,et al.Effects of moisture and density states on unsaturated shear strength of compacted expansive soil[J].Rock and Soil Mechanics,2017(s1):240-246.
[10] 戴福初,王思敬,李焯芬.香港大屿山残坡积土的残余强度试验研究[J].工程地质学报,1998,6(3):223-229.DAI F C,WANG S J,LEE C F.The drained residual strength of volcanics-derived soil sampled on Lantau Island,Hong Kong[J].Journal of Engineering Geology,1998,6(3):223-229.
[11] 康文献,周进,王玲玲,等.裂隙性膨胀土抗剪强度的试验研究[J].人民黄河,2016,38(9):131-134.KANG W X,ZHOU J,WANG L L,et al.Experimental study on shear strength of fissures expansive soil[J].Yellow River,2016,38(9):131-134.
[12] TIWARI B.A new method for the correlation of residual shear strength of the soil with mineralogical composition[J].Journal of Geotechnical and Geoenvironmental Engineering,2005,131(9):1139-1150.
[13] LI Y R,WEN B P,AYDIN A,et al.Ring shear tests on slip zone soils of three giant landslides in the Three Gorges Project area[J].Engineering Geology,2013,154(2):106-115.
[14] 徐彬,殷宗泽,刘述丽.膨胀土强度影响因素与规律的试验研究[J].岩土力学,2011,32(1):44-50.XU B,YIN Z Z,LIU S L.Experimental study on the in-fluence factors and strength laws of expansive soil[J].Rock and Soil Mechanics,2011,32(1):44-50.
[15] SKEMPTON A W.Residual strength of clays in landslides,folded strata and the laboratory[J].Géotechnique,2015,35(1):3-18.
[16] STARK T D,CHOI H,MCCONE S.Drained Shear strength parameters for analysis of landslides[J].Journal of Geotechnical and Geoenvironmental Engineering,2005,131(5):575-588.
[17] CHANDLER R J.Recent European experience of landslides in over consolidated clays and soft rocks[C].Proc.4th Int.Symposium on Landslides .Toronto:[s.n.],1984:61-81.
[18] WESLEY L D.Residual strength of clays and correlations using Atterberg limits[J].Géotechnique,2003,54(7):503-504.
[19] LUPINI J F.The drained residual strength of cohesive soil[J].Geotechnique,1981,31(1):76-76.
[20] COLLOTTA T,CANTONI R,PAVESI U,et al.A correlation between residual friction angle,gradation and the index properties of cohesive soils[J].Geotechnique,1989,392:343-346.
[21] CEPEDA-DIAZ A F,MESRI G.Residual shear strength of clays and shales[J].Géotechnique,1986,36(2):269-274.
[22] TIWARI B.A new method for the correlation of residual shear strength of the soil with mineralogical composition[J].Journal of Geotechnical and Geoenvironmental Engineering,2005,131(9):1139-1150.
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