Effects of end restraint in triaxial tests on coarse-grained soil
LU Xiao-ping1, SUN Ming-hui2, 3, CHEN Hao-feng4, CHU Fu-yong5
1. Management Division of Qinhuai River Hydraulic Engineering of Jiangsu Province, Nanjing 210022, China; 2. Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University, Nanjing 210098; 3. China Design Group Co., Ltd., Nanjing 210014, China; 4. Changzhou Architectural Research Institute Co., Ltd, Changzhou 213000, China; 5. School of Civil Engineering, Lishui University, Lishui 323000, China
Abstract：The end restraint can be eliminated by lubrication sample cap to some extent in the conventional triaxial tests. A comparison is made between the conventional triaxial tests and the end friction reduced triaxial tests in order to study the effects of the end restraint on the test results. The results show that different degrees of dilatancy is shown during the tests. The degree of volume deformation of the conventional triaxial test specimen is smaller. The measures to reduce the end friction have marked effects on the peak strength under low confining pressure. But with the increase of the confining pressure the effects of the lubrication sample cap method to reduce the end friction become worse. Under the same confining pressure, the internal friction angle , the initial Young's modulus Ei and the secant modulus E1 of the end friction reduced triaxial tests are smaller than those of the conventional triaxial tests.
陆晓平,孙明辉,陈浩锋,褚福永. 粗粒土三轴试样端部约束影响研究[J]. 岩土工程学报, 2017, 39(s1): 236-240.
LU Xiao-ping, SUN Ming-hui, CHEN Hao-feng, CHU Fu-yong. Effects of end restraint in triaxial tests on coarse-grained soil. Chinese J. Geot. Eng., 2017, 39(s1): 236-240.
[1] 朱俊高, MOHAMED A ALsakran, 龚 选, 等. 某板岩粗粒料湿化特性三轴试验研究[J]. 岩土工程学报, 2013, 35(1): 170-174. (ZHU Jun-gao, MOHAMED A ALsakran, GONG Xuan, et al. Triaxial tests on wetting deformation behavior of a slate rockfill material[J]. Chinese Journal of Geotechnical Engineering, 2013, 35(1): 170-174. (in Chinese)) [2] 缪林昌, 崔 颖, 陈可君, 等. 非饱和重塑膨胀土的强度试验研究[J]. 岩土工程学报, 2006, 28(2): 274-276. (MIAO Lin-chang, CUI Ying, CHEN Ke-jun, et al. Test on strength of unsaturated remolded expansive soils[J]. Chinese Journal of Geotechnical Engineering, 2006, 28(2): 274-276. (in Chinese)) [3] 詹良通, 吴宏伟. 非饱和膨胀土变形和强度特性的三轴试验研究[J]. 岩土工程学报, 2006, 28(2): 198-201. (ZHAN Liang-tong, NG C W W. Experimental study on mechanical behavior of recompacted unsaturated expansive clay[J]. Chinese Journal of Geotechnical Engineering, 2006, 28(2): 198-201. (in Chinese)) [4] 李云龙. 土工三轴试验中端部接触和端部约束影响研究[D].大连: 大连理工大学, 2007. (LI Yun-long. Research on influence of end contact and end restriction in soil tri-axial tests[D]. Dalian: Dalian University of Technology, 2007. (in Chinese)) [5] DUNCAN J M, DUNLOP P. The significance of cap and base restraint[J]. J Soil Mechanics and Foundations Division, ASCE, 1968, 94(1): 271-290. [6] ZHANG H, GARGA V K. Quasi-steady state: a real behavior[J]. Can Geotech J, 1997, 34(5): 749-761. [7] BISHOP A W, GREEN E G. The influence of end restraint on the compression strength of a cohesionless soil[J]. Géotechnique, 1965, 15(3): 243-266. [8] BLIGHT G E. Shear stress pore pressures in triaxial testing[J]. Journal of the Soil Mechanics and Foundations Divison, ASCE, 1965, 91(SM6): 25-39. [9] ROWE P W. The stress dilatancy relation for static equilibrium of an assembly of particles in contact[J]. Proc Royal Society, 1962(269): 500-527. [10] 陈春霖, 张惠明. 饱和砂土三轴试验中的若干问题[J]. 岩土工程学报, 2000, 22(6): 659-663. (CHEN Chun-lin, ZHANG Hui-ming. Some problems in triaxial test on saturated sands[J]. Chinese Journal of Geotechnical Engineering, 2000, 22(6): 659-663. (in Chinese)) [11] GARGA V K, ZHANG H. Volume changes in undrained triaxial tests on sands[J]. Can Geotech J, 1997, 34(5): 762-772. [12] 王助贫, 邵龙潭. 三轴试验土样的端部影响问题研究[J]. 岩土力学, 2003, 24(3): 363-368. (WANG Zhu-pin, SHAO Long-tan. Research on influence of end effect of soil specimens in triaxial tests[J]. Rock and Soil Mechanics, 2003, 24(3): 363-368. (in Chinese)) [13] 董建军, 邵龙潭. 考虑端部效应影响的非饱和压实土三轴试验研究[J]. 岩石力学与工程学报, 2010, 29(9): 1937-1944. (DONG Jian-jun, SHAO Long-tan. Study of unsaturated compacted soil considering influence of end effect by triaxial test[J]. Chinese Journal of Rock Mechanics and Engineering, 2010, 29(9): 1937-1944. (in Chinese)) [14] 石 露, 李小春. 真三轴试验中的端部摩擦效应分析[J]. 岩土力学, 2009, 30(4): 1159-1164. (SHI Lu, LI Xiao-chun. Analysis of end friction effect in true triaxial test[J]. Rock and Soil Mechanics, 2009, 30(4): 1159-1164. (in Chinese)) [15] SL237—1999土工试验规程[S]. 北京: 中国水利水电出版社, 1999. (SL237—1999 Specification of soil test[S]. Beijing: China Water & Power Press, 1999. (in Chinese))
