加筋粗粒土直剪力学行为与颗粒破碎特性

Mechanical behaviors and particle breakage features of reinforced coarse-grained soil in direct shear test

粗粒土是一种天然填筑材料,在工程中应用广泛。大量学者对加筋粗粒土的力学性质进行了研究,但对直剪过程中颗粒破碎特性尚无人研究。本文采用大型直剪仪,对粗粒土和加筋粗粒土进行了直剪试验研究,研究了其直剪力学行为与直剪过程中的颗粒破碎特性。试验结果表明:粒径和垂直压力越大,峰值强度越大;加筋后,黏聚力均大幅提高,而内摩擦角有一定程度的减小,黏聚力和内摩擦角均随着粒径的增大而增大;土工格栅除了受到与土的摩擦力外,还受到土体对横肋的阻挡力,阻挡力大幅提高了黏聚力;由不同方法计算得到的颗粒破碎率均随着垂直压力的增大而增大。垂直压力越大,颗粒间的接触越紧密,相互作用越剧烈,破碎率越大。同时在相同垂直压力下粒径越大,破碎越严重。加筋后颗粒破碎率显著降低,加筋可以有效防止颗粒破碎。

Coarse-grained soil is natural filling material widely used in engineering.A large number of scholars have studied the mechanical properties of reinforced coarse-grained soil,while the particle breakage characteristics of coarse-grained soil have not been investigated yet.In this paper,mechanical properties and particle breakage characteristics of coarse-grained soil and reinforced coarse-grained soil are studied in large-scale direct shear tests.Results show that an increase in particle size and vertical pressure produced larger peak strength.Reinforced coarse-grained soil has increasing cohesion,but decreasing internal friction angle.Cohesion and internal friction angle are increased with the increase of particle size.Besides the friction between soil and geogrid,the cross rib produces resistance to soil,greatly improving the cohesion.Particle breakage indexes from different calculation methods increases with the increase of vertical pressure.Larger vertical pressure result in intense contact between particles.The strong interaction causes more particle breakage.The reinforcement significantly decreases particle breakage index.The more particle breakage occur with larger particle size.Reinforcement can effectively prevent particle breakage.