中文摘要：

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△h’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△h’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．

英文摘要：

Direct shearing tests on three groups of sand were carried out under a normal pres- sure of 0.4-12.0 MPa with an in-house developed DRS-1 high pressure direct shearing test system. The results show that the shearing mechanical properties and volumetric strain proper- ties are affected by the combination of normal pressure and particle size, which is called load effect and particle size effect in this paper. Shearing energy dissipation factor and shear volu- metric strain parameter h decrease nonlinearly with the increase of normal pressure, which be- comes more notable as the sand particle size increases. Shearing energy dissipation factor in- creases with the increase of sand particle size, which could be neglected under high pressure. Shear volumetric strain parameter h is influenced by particle size, however the influencing char- acteristics behave differently when subjected to low pressure and high pressure respectively. The normal pressure affects the degree of particle breakage so as to inpact the energy consump- tion modes of sand shearing, which is defined as load effect mechanism of sand shearing proper- ties. The particle size effect mechanisms are different under different normal pressure： the particle size will affect the thickness of the particle displacement belt area while under low normal pressure; and under high normal pressure, the size will affect the degree of particle breakage.