石笼网护岸结构强度和变形特性试验研究

Experimental Study on Strength and Deformation Characteristics of Gabion Net Revetment Structure

石笼网内填石料的填充率与石笼单体结构强度指标是石笼网生态护坡技术研究中的关键指标.采用室内石笼网填充率试验,进行了填石料的最小干密度与颗粒级配相关性研究,确定了石笼网单体结构大型直剪试验中填石料的级配曲线.利用NHRI-4000型高性能大接触面直剪仪,进行了相同粒径和剪切条件下有无石笼网的填石料剪切比对试验.试验结果表明:石笼网填充率随逊径颗粒含量的增大而增大;当试样粒径小于40 mm的颗粒(P<40)的质量分数为60%时,结合一定的击实措施,石笼网内碎石能达到最佳填充效果,填充率为72%,满足设计指标要求.石笼网结构是由填石料与石笼网组成的复合体,有石笼网的填石料抗剪强度远大于没有石笼网的填石料抗剪强度;石笼网的弹性模量远高于填石料的弹性模量,石笼网的"环箍"效应限制了填石料间颗粒的移动,增加了填石料整体稳定性;在变形特性上,除石笼单体结构整体延展性较大外,其发生应变软化和硬化的情况与一般粗粒土的变形特性基本一致.

The stone filling rate and the strength index of individual structure for gabion net are the key indexes in studying the ecological revetment technology of gabion net cushion.Through the indoor filling rate test of gabion net,the correlation between the minimum dry density and grain size gradation of rockfill is studied,and the rockfill gradation curve of a single structure for gabion net is determined by a large-scale direct shear test.Using NHRI-4000 high-performance direct shear apparatus with large contact surface,the shearing comparison tests of rockfill are carried out for the specimens with or without a gabion net under the same particle size and shear conditions.The test results show that the filling rate of gabion net increases with the increase of inferior diameter particles content.When the P<40 content is 60%,combined with certain compaction measures,the crushed stones in gabion net can reach the best filling effect(the filling rate is 72%),which meets the design requirements for revetment projects.The gabion net structure is a composite composed of rockfill and the gabion net.The shear strength of rockfill with gabion net is much greater than that of rockfill without gabion net.The elastic modulus of gabion net is much higher than that of the rockfill.The“hoop”effect of the gabion net restricts particle movement and increases the overall stability of rockfill.In terms of deformation characteristics,except for the overall ductility of the gabion structure,its strain softening and hardening are basically consistent with the deformation characteristics of general coarse-grained soil.