粗颗粒土橡皮膜嵌入试验研究
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摘要
对于粗颗粒土三轴固结排水剪试验,橡皮膜嵌入是影响试验体变测量的最重要因素。通过在中三轴试样中埋置不同直径铁棒的方法进行等向固结试验来推求橡皮膜嵌入量。试验表明,试样土体体积与排水量呈较好的线性关系,基此给出了各个围压下的膜嵌入量。指出随着围压的增大,膜嵌入量逐渐增大,约0.8 MPa后,嵌入量的增速变缓,嵌入量占实时总排水量的比例可达31.0%~40.7%。由于粗颗粒土的各向异性,目前所用最多的Newland和Allely所提出的方法总体略高估了膜嵌入的大小,随着围压的增大,各向异性减弱,围压为2 MPa时嵌入量差异仅有0.22%的体变。最后,对比4种解析解发现Molenkamp和Luger的解析解最为接近试验值。针对粗颗粒土,需要进行更多的试验来建立颗粒破碎率和相对密度等与系数η的关系来修正解析解。
The membrane penetration is the most important factor influencing the measurement of volume change for triaxial consolidated-drained shear tests on coarse grained soil. The volume changes of membrane penetration are deduced from the consolidation tests by the method that iron rods with different diameters are embedded in the triaxial samples. The test results indicate the linear relationship between the sample volume and the displacement. Based on the test results, the penetration volumes are given under each confining pressure. The volume of membrane penetration increases by the increase of confining pressure, however, the increasing speed becomes slow down after 0.8 MPa. The proportion of penetration volume in total displacement can be 31.0%~40.7%. The most used method proposed by Newland and Alley overestimates the penetration volume. Anisotropy of the triaxial sample decreases with the increase of confining pressure. The difference of penetration volume is only 0.22% of volume change when the confining pressure reaches 2 MPa. The analytic solution deduced by Molenkamp and Luger agrees well with the test results among the four analytic solutions. For the coarse grained soil, more tests should be done to establish the relation among the particle breakage rate, the relative density and the coefficient η to correct the analytical solution.
The membrane penetration is the most important factor influencing the measurement of volume change for triaxial consolidated-drained shear tests on coarse grained soil. The volume changes of membrane penetration are deduced from the consolidation tests by the method that iron rods with different diameters are embedded in the triaxial samples. The test results indicate the linear relationship between the sample volume and the displacement. Based on the test results, the penetration volumes are given under each confining pressure. The volume of membrane penetration increases by the increase of confining pressure, however, the increasing speed becomes slow down after 0.8 MPa. The proportion of penetration volume in total displacement can be 31.0%~40.7%. The most used method proposed by Newland and Alley overestimates the penetration volume. Anisotropy of the triaxial sample decreases with the increase of confining pressure. The difference of penetration volume is only 0.22% of volume change when the confining pressure reaches 2 MPa. The analytic solution deduced by Molenkamp and Luger agrees well with the test results among the four analytic solutions. For the coarse grained soil, more tests should be done to establish the relation among the particle breakage rate, the relative density and the coefficient η to correct the analytical solution.
引文
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[14]龚选.粗粒土强度特性及三轴试验橡皮膜影响的研究[D].南京:河海大学,2014.(GONG Xuan.Test Study on effects of rubber membrane constraint in triaxial test and strength characteristics of coarse-grained soil[D].Nanjing:Hohai University,2014.(in Chinese))
[15]施维成,刘汉龙,朱俊高,等.粗粒土应力诱导各向异性真三轴试验研究[J].岩土工程学报,2011,32(5):810–814.(SHI Wei-cheng,LIU Han-long,ZHU Jun-gao,et al.Stress-induced anisotropy of coarse-grained soil by true triaxial tests[J].Chinese Journal of Geotechnical Engineering,2011,32(5):810–814.(in Chinese))
[16]MOLENKAMP F,LUGER H J.Modelling and minimization of membrane penetration effects in tests on granular soils[J].Géotechnique,1981,31(4):471–486.
[17]BALDI G,NOVA R.Membrane penetration effects in triaxial testing[J].Journal of Geotechnical Engineering,1984,110(3):403–420.
[18]KRAMER S L,SIVANESWARAN N.A nondestructive,specimen-specific method for measurement of membrane penetration in the triaxial tests[J].Geotechnical Testing Journal,1989,12(1):50–59.
[19]KRAMER S L,SIVANESWARAN N,DAVIS R O.Analysis of membrane penetration in triaxial test[J].Journal of Engineering Mechanics,1990,116(4):773–789.
[20]TIMOSHENKO S P,WOINOWSKY,KRIEGER S.Theory of plates and shells[M].Amsterdam:Mc Graw-hill,1959.
[21]贾宇峰,迟世春,杨峻,等.粗粒土的破碎耗能计算及影响因素[J].岩土力学,2009,30(7):1960–1966.(JIA Yu-feng,CHI Shi-chun,YANG Jun,et al.Measurement of breakage energy of coarse granular aggregates[J].Rock and Soil Mechanics,2009,30(7):1960–1966.(in Chinese))
[22]NOOR M J M,NYUIN J D,DERAHMAN A.A graphical method for membrane penetration in triaxial tests on granular soils[J].J Inst Eng,Malaysia,2012,73(1):23–30.
[2]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-ping,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))
[3]郭爱国,茜平一.三轴压缩试验中橡皮膜约束影响的校正[J].岩土力学,2002,23(4):442–445.(GUO Ai-guo,QIAN Ping-yi.Corrections for influence of membrane restraint in triaxial tests[J].Rock and Soil Mechanics,2002,23(4):442–445.(in Chinese))
[4]NEWLAND P L,ALLELY B H.Volume changes in drained taixial tests on granular materials[J].Géotechnique,1957,7(1):17–34.
[5]张丙印,吕明治,高莲士.粗粒料大型三轴试验中橡皮膜嵌入量对体变的影响及校正[J].水利水电技术,2003,34(2):30–33.(ZHANG Bing-yin,LüMing-zhi,GAO Lian-shi.Correction of membrane penetration in large-scale triaxial tests for granular materials[J].Water Resources and Hydropower Engineering,2003,34(2):30–33.(in Chinese))
[6]ROSCOE K H,SCHOFIELD A N,THURAIRAJAH A.An evaluation of test data for selecting a yield criterion for soils[M]//Laboratory Shear Testing of Soils.ASTM International,Philadelphia,1964.
[7]FRYDMAN S,ZEITLEN J G,ALPAN I.The membrane effect in triaxial testing of granular soils[J].Journal of Testing and Evaluation,1973,1(1):37–41.
[8]KIEKBUSCH M,SCHUPPENER B.Membrane penetration and its effect on pore pressures[J].Journal of the Soil Mechanics and Foundations Division,1977,103(11):1267–1279.
[9]RAJU V S,VENKATARAMANA K.Undrained triaxial tests to assess liquefaction potential of sands:effect of membrane penetration[C]//Proceedings of the International Symposium on Soils under Cyclic Transient loading.Rotterdam,1980:483–494.
[10]LIN H,SELIG E T.An alternative method for determining the membrane penetration correction curve[J].Geotechnical Testing Journal,1987,10(3):151–155.
[11]BOHAC J,FEDA J.Membrane penetration in triaxial tests[J].Geotechnical Testing Journal,1992,15(3):288–294.
[12]ALI S R,PYRAH I C,ANDERSON W F.A novel technique for evaluation of membrane penetration[J].Géotechnique,1995,45(3):545–548.
[13]RAGHUNANDAN M,JUNEJA A,HSIUNG B.Preparation of reconstituted sand samples in the laboratory[J].International Journal of Geotechnical Engineering,2012,6(1):125–131.
[14]龚选.粗粒土强度特性及三轴试验橡皮膜影响的研究[D].南京:河海大学,2014.(GONG Xuan.Test Study on effects of rubber membrane constraint in triaxial test and strength characteristics of coarse-grained soil[D].Nanjing:Hohai University,2014.(in Chinese))
[15]施维成,刘汉龙,朱俊高,等.粗粒土应力诱导各向异性真三轴试验研究[J].岩土工程学报,2011,32(5):810–814.(SHI Wei-cheng,LIU Han-long,ZHU Jun-gao,et al.Stress-induced anisotropy of coarse-grained soil by true triaxial tests[J].Chinese Journal of Geotechnical Engineering,2011,32(5):810–814.(in Chinese))
[16]MOLENKAMP F,LUGER H J.Modelling and minimization of membrane penetration effects in tests on granular soils[J].Géotechnique,1981,31(4):471–486.
[17]BALDI G,NOVA R.Membrane penetration effects in triaxial testing[J].Journal of Geotechnical Engineering,1984,110(3):403–420.
[18]KRAMER S L,SIVANESWARAN N.A nondestructive,specimen-specific method for measurement of membrane penetration in the triaxial tests[J].Geotechnical Testing Journal,1989,12(1):50–59.
[19]KRAMER S L,SIVANESWARAN N,DAVIS R O.Analysis of membrane penetration in triaxial test[J].Journal of Engineering Mechanics,1990,116(4):773–789.
[20]TIMOSHENKO S P,WOINOWSKY,KRIEGER S.Theory of plates and shells[M].Amsterdam:Mc Graw-hill,1959.
[21]贾宇峰,迟世春,杨峻,等.粗粒土的破碎耗能计算及影响因素[J].岩土力学,2009,30(7):1960–1966.(JIA Yu-feng,CHI Shi-chun,YANG Jun,et al.Measurement of breakage energy of coarse granular aggregates[J].Rock and Soil Mechanics,2009,30(7):1960–1966.(in Chinese))
[22]NOOR M J M,NYUIN J D,DERAHMAN A.A graphical method for membrane penetration in triaxial tests on granular soils[J].J Inst Eng,Malaysia,2012,73(1):23–30.