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采用自行研制的DRS-1型高压直剪试验系统进行了法向压力0.4~12.0MPa条件下3种不同粒组砂的直剪试验.结果表明,砂土的剪切力学特性与剪切体变特性受法向压力与粒径共同影响,称为荷载效应与粒径效应.剪切耗能因子与剪切体变参数Δh′随法向压力的增大呈非线性减小,这一趋势随粒径增大而更加明显.剪切耗能因子随砂土粒径的增大而增大,但在高压条件下可以忽略.剪切体变参数Δh′受粒径影响,在低压与高压下呈现不同的规律.法向压力影响颗粒破碎程度,进而影响砂土剪切耗能方式,即砂土剪切特性的荷载效应机制.粒径效应在不同法向压力下的机制不同:低法向压力下,粒径影响颗粒变位带状区的厚度;高法向压力下,粒径影响砂土颗粒剪切破碎程度.
The direct shear test of 3 different sand pellets under the condition of normal pressure 0.4 ~ 12.0MPa was carried out by the self-developed DRS-1 high-pressure direct shear test system.The results show that the shear properties of the sand and shear deformation The characteristic is affected by both the normal pressure and the particle size, and is called the load effect and particle size effect. The shear energy dissipation factor and the shear parameter Δh ’decrease nonlinearly with the increase of the normal pressure, The particle size increases and becomes more obvious.The shear energy dissipation factor increases with the increase of sand particle size, but can be neglected under high pressure conditions.The shear parameter Δh ’is affected by the particle size, under low pressure and high pressure The normal pressure exerts influence on the degree of particle crushing, and then affects the shear energy dissipation mode of sand, namely the load effect mechanism of sand shear characteristics.The mechanism of particle size effect under different normal pressures is different: low normal Under the pressure, the particle size affects the thickness of the strip zone. Under the high normal pressure, the particle size affects the shear fragmentation of sand particles.