季节性冻土中土工格栅加筋特性试验研究
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摘要
针对东北地区典型粉质黏土,通过一系列土工格栅在冻土中的拉拔试验,重点分析了土壤含水率及冻融循环作用对土工格栅加筋性能的影响,并基于拉拔摩擦强度、表观摩擦系数、界面摩擦阻力和端承被动阻力等理论,对试验数据进行了详细分析。研究发现:含水率对土工格栅加筋效果存在明显抑制作用,含水率从20%提高至32%时,筋土界面摩擦阻力和端承被动阻力均减小60%以上。而当含水率一定时(w=24%),冻融循环作用反而提高了土工格栅的加筋效果,经历7次冻融循环后,土工格栅加筋效果增幅为30%左右,主要是横肋前端承被动阻力的提高,而筋土间界面摩擦阻力变化不大。上述试验成果可为土工格栅在冻土地区的推广应用提供一定的理论依据。
A series of pullout tests to investigate the reinforced characteristics of geogrids in frozen soil are conducted in the laboratory under various moisture contents and different freeze-thaw cycles. Based on the theories about frictional strength, apparent friction coefficient, interface frictional resistance and passive resistance, the test data are analyzed. Some conclusions are drawn that the moisture content can obviously inhibit the effect of reinforcement. The interface frictional resistance and passive resistance both decrease to 40% while the moisture content increases from 20% to 32%. Then the moisture content is constant to 24%, the freeze-thaw cycles can improve the reinforcement effect of geogrids. Mainly for the passive resistance has a certain extent enhancement, but the interface frictional resistance nearly has no change. The experimental results are of referring value for the design of geogrids-reinforced earth structures.
A series of pullout tests to investigate the reinforced characteristics of geogrids in frozen soil are conducted in the laboratory under various moisture contents and different freeze-thaw cycles. Based on the theories about frictional strength, apparent friction coefficient, interface frictional resistance and passive resistance, the test data are analyzed. Some conclusions are drawn that the moisture content can obviously inhibit the effect of reinforcement. The interface frictional resistance and passive resistance both decrease to 40% while the moisture content increases from 20% to 32%. Then the moisture content is constant to 24%, the freeze-thaw cycles can improve the reinforcement effect of geogrids. Mainly for the passive resistance has a certain extent enhancement, but the interface frictional resistance nearly has no change. The experimental results are of referring value for the design of geogrids-reinforced earth structures.
引文
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[2]汪恩良,徐学燕.低温条件下塑料土工格栅拉伸特性的试验研究[J].岩土力学,2008,29(6):1507-1511.(WANG En-liang,XU Xue-yani.Experimental study on tensile characteristics of plastic geogrid under low temperature[J].Rock and Soil Mechanics,2008,29(6):1507-1511.(in Chinese))
[3]HAYNES F D,COLLINS C M,OLSON W W.Bearing capacity tests on ice reinforced with geogrids[R].The American Society of Mechanical Engineers,1992.
[4]马巍,刘端,吴青柏.青藏铁路冻土路基变形监测与分析[J].岩土力学,2008,39(3):571-579.(MA Wei,LIUDuan,WU Qing-bai.Monitoring and analysis of embankment deformation in permafrost regions of Qinghai-Tibet Railway[J].Rock and Soil Mechanics,2008,39(3):571-579.(in Chinese))
[5]苏艺,许兆义,王连俊.青藏高原多年冻土区铁路加筋路堤的变形特征研究[J].岩土工程学报,2004,26(1):115-119.(SU Yi,XU Zhao-yi,WANG Lian-jun.Study on deformation characters of reinforced embankment in permafrost regions of Qinghai-Tibet Railway[J].Chinese Journal of Geotechnical Engineering,2004,26(1):115-119.(in Chinese))
[6]王引生.土工格栅在青藏铁路多年冻土区路基工程中的应用[J].冰川冻土,2003,25(3):355-358.(WANG Yin-sheng.Application of geotechnical lattices to subgrade engineering in the permafrost regions of the Qinghai-Tibet Railway[J].Journal of glaciology and geocryology,2003,25(3):355-358.(in Chinese))
[7]裴建中,窦明健,胡长顺,等.土工合成材料在多年冻土地区路基病害处治中的应用技术研究[J].冰川冻土,2002,24(6):785-789.(PEI Jian-zhong,DOU Ming-jian,HU Chang-shun,et al.Application of geosynthetics for treatment of subgrade troubles in permafrost regions[J].Journal of Glaciology and Geocryology,2002,24(6):785-789.(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 Jun-jie,CAO Wen-zhao,ZHOU Yan-jun,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]PETERSON L M,ANDERSON L R.Pullout resistance of welded wire mats embedded in soil[R].Utah:Utah State University,1980.
[10]JEWELL R A,MILLIGAN G W E,SARSBY R W,et al.Interaction between soil and geogrids[C]//Proc Symp on Polymer Grid Reinforcement in Civil Engineering,Science and Engineering Research Council and Netlon Limited.London,1984:18-30.
[11]陈榕,郝冬雪,栾茂田,等.土工格栅横肋与纵肋加筋机理研究[J].建筑材料学报,2013,16(6):544-548.(CHEN Rong,HAO Dong-xue,LUAN Mao-tian,et al.Reinforcement mechanism of transverse and longitudinal geogrid ribs[J].Journal of Building Materials,2013,16(6):544-548.(in Chinese))