基于P_5含量的砂砾土与格栅拉拔试验及破坏特性分析
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摘要
为研究砂砾土P_5(粒径>5 mm的粗颗粒质量百分比)对土工格栅拉拔性状及破坏特性的影响,利用土工合成材料综合测定仪对不同P_5的砂砾土进行了拉拔试验,系统地研究了P_5对拉拔力峰值、格栅破坏形式的影响及格栅拉拔阻力在不同填筑方式下的变化规律.试验结果表明:在同一法向应力下,当P_5由20%增长为30%时,拉拔力峰值增长为原来的1.1倍左右;当P_5相同时,随着法向应力的增加,格栅破坏从撕裂演变为劈裂,法向应力每增加25 kPa,横向撕裂长度扩大2倍左右;当法向应力一致时,改变P_5,格栅破坏形式基本一致;在相同竖向压力与P_5含量下,分别采取击实填筑与压实填筑砂砾土,拉拔曲线分别表现为软化、硬化两种截然不同的发展趋势.
Aiming at studying the influence of gravel soil P_5 on the pullout test behavior of geogrid, the P_5 peak pull-out force, geogrid failure form and the development law of geogrid force-displacement curve under different filling methods were systematically studied by the geosynthetics comprehensive measuring instrument which was used to carried out pullout test by the gravel soil of different P_5. The test results indicate that under the same normal stress, when P_5 improve from 20% to 30%, the peak pull-out force increases about 1.1 times. In some test groups, the tensile modulus cannot be measured due to the low elastic modulus of the geogrid. When at constant P_5, as the normal stress increases, the geogrid failure form changes from tear to split. When the normal stress increases 25 kPa, the lateral tear length expands by about 2 times. When the normal stress is consistent, change P_5, the form of failure is very similarly; under the same vertical pressure and P_5 content, compaction and press of gravel soil will result in two distinct development trends: strain softening and hardening of the pullout curve.
Aiming at studying the influence of gravel soil P_5 on the pullout test behavior of geogrid, the P_5 peak pull-out force, geogrid failure form and the development law of geogrid force-displacement curve under different filling methods were systematically studied by the geosynthetics comprehensive measuring instrument which was used to carried out pullout test by the gravel soil of different P_5. The test results indicate that under the same normal stress, when P_5 improve from 20% to 30%, the peak pull-out force increases about 1.1 times. In some test groups, the tensile modulus cannot be measured due to the low elastic modulus of the geogrid. When at constant P_5, as the normal stress increases, the geogrid failure form changes from tear to split. When the normal stress increases 25 kPa, the lateral tear length expands by about 2 times. When the normal stress is consistent, change P_5, the form of failure is very similarly; under the same vertical pressure and P_5 content, compaction and press of gravel soil will result in two distinct development trends: strain softening and hardening of the pullout curve.
引文
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[2] VANGLA P,LATHA G M. Influence of particle size on the friction and interfacial shear strength of sands of similar morphology[J]. International Journal of Geosynthetics and Ground Engineering,2015,1(1):6.
[3] VANGLA P,GALI M L. Effect of particle size of sand and surface asperities of reinforcement on their interface shear behaviour[J]. Geotextiles and Geomembranes,2016,44(3):254-268.
[4] MAKKAR F M,CHANDRAKARAN S,SANKAR N. Experimental investigation of response of different granular soil–3D geogrid interfaces using large-scale direct shear tests[J]. Journal of Materials in Civil Engineering, 2019, 31(4):04019012.
[5] MORACI N,CAZZUFFI D,CALVARANO L S,et al. The influence of soil type on interface behavior under pullout conditions[J].Geosynthetics,2014,32(3):42-50.
[6]孙田,陈国兴,王炳辉,等.砾石颗粒形状对砂砾土动剪切模量和阻尼比影响的试验研究[J].岩石力学与工程学报,2014,33(S2):4211-4217.
[7]赵凯,周建军,孙田,等.考虑排水条件和粗料含量的砂砾石土动残余变形特性[J].岩土力学,2018,39(3):926-932.
[8]吴琪,陈国兴,周正龙,等.细粒含量对细粒–砂粒–砾粒混合料动强度的影响[J].岩土工程学报,2017,39(6):1038-1047.
[9]王炳辉,陈国兴,孙田,等.砂砾土抗液化强度的小型土箱振动台试验研究[J].岩土工程学报,2015,37(11):2094-2100.
[10]中华人民共和国水利部.土工试验规程:SL237-1999[S].北京:中国水利水电出版社,1999.
[11]王家全,武标,邹红,等.土工格栅与粗粒土界面特性的大型直剪试验研究[J].广西科技大学学报,2015,26(3):78-83.
[12]左永振,张婷,丁红顺. P5含量对滑坡体砾质土的力学性质影响试验研究[J].西北地震学报,2011,33(S1):223-226.
[13]饶锡保,何晓民,刘鸣.粗粒含量对砾质土工程性质影响的研究[J].长江科学院院报,1999,16(1):21-25.
[14]南京水利科学研究院.土工合成材料测试规程:SL 235-2012[S].北京:中国水利水电出版社,2012.