双向和三向土工格栅筋土界面特性对比试验研究
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摘要
以双向土工格栅SS20和三向土工格栅TX160为对象,通过开展室内直剪试验和拉拔试验,并对拉拔试验中土工格栅试样4个断面的位移进行量测,研究了SS20和TX160的变形及筋土界面特性,对比分析了SS20和TX160方案的筋土界面剪应力发挥过程和作用机制、土工格栅变形、筋土界面剪胀(缩)特性和强度参数,同时探讨了试验方法对试验结果的影响.研究结果表明:拉拔试验中,TX160的筋土相互作用集中在拉拔端附近,而SS20沿试样全长均能较好地发挥其作用;相比于SS20,增大竖向压力可以更好地增强TX160与周围填料颗粒的相互作用;SS20方案的峰值摩擦角和残余摩擦角均大于TX160方案,但黏聚力刚好相反;竖向压力对直剪试验和拉拔试验所得筋土界面强度参数均有明显影响,实际工程应用中应根据土工格栅的实际应力状态确定合理的试验竖向压力.
Laboratory direct shear test and pullout test were conducted focusing on biaxial geogrid(SS20) and triaxial geogrid(TX160)to investigate the deformation and geogrid-soil interface behavior. The displacements of ge-ogrid specimens were recorded at 4 sections in the pullout test. The development of geogrid-soil interface shear stress, geogrid deformation, shear dilatancy/shrinkage behavior and interface parameters were analyzed, and the ef-fect of test methods on the testing results was also investigated. The results show that the interaction between the ge-ogrid and soil of TX160 concentrates at the vicinity of pullout end. However, this interaction is well developed along the full length of SS20 specimens. Meanwhile, this interaction of TX160 can be better enhanced with the increase of vertical stress compared with that of SS20. Both the peak and residual friction angles of SS20 case are greater than that of TX160 case, while the cohesion is just opposite. The vertical stress has obvious effect on the geogrid-soil interface strength parameters obtained from both the direct shear test and pullout test. Thus, the vertical stress adopted in the test should be determined based on the actual stress status of the geogrid for engineering application.
Laboratory direct shear test and pullout test were conducted focusing on biaxial geogrid(SS20) and triaxial geogrid(TX160)to investigate the deformation and geogrid-soil interface behavior. The displacements of ge-ogrid specimens were recorded at 4 sections in the pullout test. The development of geogrid-soil interface shear stress, geogrid deformation, shear dilatancy/shrinkage behavior and interface parameters were analyzed, and the ef-fect of test methods on the testing results was also investigated. The results show that the interaction between the ge-ogrid and soil of TX160 concentrates at the vicinity of pullout end. However, this interaction is well developed along the full length of SS20 specimens. Meanwhile, this interaction of TX160 can be better enhanced with the increase of vertical stress compared with that of SS20. Both the peak and residual friction angles of SS20 case are greater than that of TX160 case, while the cohesion is just opposite. The vertical stress has obvious effect on the geogrid-soil interface strength parameters obtained from both the direct shear test and pullout test. Thus, the vertical stress adopted in the test should be determined based on the actual stress status of the geogrid for engineering application.
引文
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[16]徐超,孟凡祥.剪切速率和材料特性对筋-土界面抗剪强度的影响[J].岩土力学,2010,31(10):3101—3106.XU C,MENG F X. Effects of shear rate and material properties on shear strength of geosynthetic-soil interface[J]. Rock and Soil Mechanics,2010,31(10):3101—3106.(In Chinese)
[17]杜勇立,高礼,杨果林.不同掺土量加筋煤矸石的界面摩擦试验研究[J].湖南大学学报(自然科学版),2014,41(4):54—60.DU Y L,GAO L,YANG G L. Experimental study of the interface friction characteristics between coal gantue and reinforcement with different qualities of soil[J]. Journal of Huan University(Natural Sciences),2014,41(4):54—60.(In Chinese)
[2] DONG Y L,HAN J,BAI X H. Numerical analysis of tensile behavior of geogrid with rectangular and triangular apertures[J].Geotextiles and Geomembranes,2011,29(2):83—91.
[3] QIAN Y,HAN J,POKHAREL S K,et al. Performance of triangular aperture geogrid-reinforced base courses over weak subgrade under cyclic loading[J]. Journal of Materials in Civil Engineering,2013,25(8):1013—1021.
[4] CHEN C,MCDOWELL G R,THOM N H. Discrete element modeling of cyclic loads of geogrid-reinforced ballast under confined and unconfined conditions[J]. Geotextiles and Geomembranes,2012,35:76—86.
[5]马时冬.土工格栅与土的界面摩擦特性试验研究[J].长江科学院院报,2004,21(1):11—14.MA S D. Testing study on soil interface characteristics of geosynthetics[J]. Journal of Yangtze River Scientific Research Institute,2004,21(1):11—14.(In Chinese)
[6] TEIXEIRA S H C,BUENO B S,ZORNBERG J G. Pullout resistance of individual longitudinal and transverse geogrid ribs[J].Journal of Geotechnical and Geoenvironmental Engineering,2007,133(1):37—50.
[7]史旦达,刘文白,水伟厚,等.单、双向塑料土工格栅与不同填料界面作用特性对比试验研究[J].岩土力学,2009,30(8):2237—2244.SHI D D,LIU W B,SHUI W H,et al. Comparative experimental studies of interface characteristics between uniaxial/biaxial plastic geogrids and different soils[J]. Rock and Soil Mechanics,2009,30(8):2237—2244.(In Chinese)
[8]郑俊杰,曹文昭,周燕君,等.三向土工格栅筋-土界面特性拉拔试验研究[J].岩土力学,2017,38(2):317—324.ZHENG J J,CAO W Z,ZHOU Y J,et al. Pull-out test study of interface behavior between triaxial geogrid and soil[J]. Rock and Soil Mechanics,2017,38(2):317—324.(In Chinese)
[9]周芬,周智敏,杜运兴.压实度对加筋土竖向变形影响的试验研究[J].湖南大学学报(自然科学版),2017,44(5):73—79.ZHOU F,ZHOU Z M,DU Y X. Experimental study on influence of compaction degree on vertical deformation of reinforced soil[J].Journal of Huan University(Natural Sciences),2017,44(5):73—79.(In Chinese)
[10]徐林荣.筋土界面参数测试方法合理选择研究[J].岩土力学,2003,24(3):458—462.XU L R. Research on selection of measuring method of interface parameters between reinforcements and soils[J]. Rock and Soil Mechanics,2003,24(3):458—462.(In Chinese)
[11]土工合成材料工程应用手册编写委员会.土工合成材料工程应用手册[M]. 2版.北京:中国建筑工业出版社,2000:95—100.Editorial Board of the Handbook about Application of Geosynthetics in Engineering.The handbook about application of geosynthetics in engineering[M]. 2nd ed.Beijing:China Architecture and Building Press,2000:95—100.(In Chinese)
[12]包承纲.土工合成材料应用原理与工程实践[M].北京:中国水利水电出版社,2008:142—147.BAO C G. The principle and application of geosynthetics in engineering[M]. Beijing:China Water&Power Press,2008:142—147.(In Chinese)
[13]刘文白,周健.土工格栅与土界面作用特性试验研究[J].岩土力学,2009,30(4):965—970.LIU W B,ZHOU J. Experimental research on interface friction of geogrids and soil[J]. Rock and Soil Mechanics,2009,30(4):965—970.(In Chinese)
[14]刘飞禹,王攀,王军,等.不同剪切速率下格栅-土界面循环剪切及其后直剪特性[J].岩石力学与工程学报,2016,35(2):387—395.LIU F Y,WANG P,WANG J,et al. Cyclic and post-cyclic shear behavior of sand-geogrid interface under different shear rates[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(2):387—395.(In Chinese)
[15]SL 235—2012土工合成材料试验规程[S].北京:中国水利水电出版社,2012:80—85.SL 235—2012 Specification for test and measurement of geosynthetics[S]. Beijing:China Water&Power Press,2012:80—85.(In Chinese)
[16]徐超,孟凡祥.剪切速率和材料特性对筋-土界面抗剪强度的影响[J].岩土力学,2010,31(10):3101—3106.XU C,MENG F X. Effects of shear rate and material properties on shear strength of geosynthetic-soil interface[J]. Rock and Soil Mechanics,2010,31(10):3101—3106.(In Chinese)
[17]杜勇立,高礼,杨果林.不同掺土量加筋煤矸石的界面摩擦试验研究[J].湖南大学学报(自然科学版),2014,41(4):54—60.DU Y L,GAO L,YANG G L. Experimental study of the interface friction characteristics between coal gantue and reinforcement with different qualities of soil[J]. Journal of Huan University(Natural Sciences),2014,41(4):54—60.(In Chinese)