不同含水率砂卵石围岩宏细观力学特性研究

含水率对具有颗粒物质性质的隧道砂卵石围岩稳定性有较大影响,通过室内大型三轴试验与颗粒离散元数值三轴试验相结合的方法,对中密状态下不同含水率砂卵石围岩在100、200、300 kPa三种围压下的宏细观力学特性展开研究,分析了含水率对隧道砂卵石围岩宏细观力学参数影响规律。研究结果表明:随着含水率的增加,砂卵石围岩的应力峰值、内摩擦角和粘聚力均随之减小;砂卵石围岩变形破坏时轴向应变约为4%,其应力峰值后仍可承受较大的应力特性;确定了中密状态时不同含水率砂卵石围岩的接触模量、摩擦系数、颗粒刚度比、法向接触强度等离散元细观参数。研究成果为砂卵石地层隧道围岩稳定性离散元精细化模拟提供理论依据。

Research on Macro-Meso Mechanical Properties of Sandy Cobble Surrounding Rock with Different Moisture Content

Moisture content has a great influence on the stability of surrounding rock of tunnel with granular material. Using both three axis test and particle discrete element numerical three axis test with different moisture content, research on macro mechanic and micromechanics properties of different content of coarse sandy pebble surrounding rock under three kinds of confining pressure, including 100 kPa, 200 kPa, 300 kPa were conducted. The influence of moisture content on the macro microscopic mechanics parameter properties of pebble tunnel surrounding rock were analyzed. The results show that: with the increase of the moisture content, the peak stress of the surrounding rock, internal friction angle and cohesive force decrease; When sandy cobble of surrounding rock deformation and failure, the axial strain is about 4%. After the stress peak value, the sandy cobble of surrounding rock can still bear larger stress. Mesoscopic parameters such as contact modulus, friction coefficient, particle stiffness ratio porosity and the normal contact strength of different coarse contents sandy pebble were determined. Research results provide a theoretical basis for discrete element fine simulation of sandy cobble stratum tunnel surrounding rock stability.