In this research,triaxial shear tests under different stress levels and initial hydration damages were carried out on sandstone-grout composite specimens under different normal stresses and immersion times to investigate the shear mechanical properties of rock-grout composite structures.The results showed that the increased damage induced by hydration significantly reduced the shear resistances of the rock and the bonding surface,increased the deformation amount of the specimen and degraded its bearing capacity.The shear strength of the specimens decreased by 23.14％-3 5.46％under the condition of 30 d of immersion,while maintaining the same normal stress level.The increase of normal stress restricted the development of micro-fractures in the specimen and improved the bearing ability.The shear strength of the specimens increased by 97.15％-137.12％with increasing normal stress,while maintaining the same immersion time.The shear failure mode of the composite specimens is limited by the stress level and initial hydration damage.There were three typical failure modes,including shear slip along the rock-grout interface,mixed shear failure and partial rock failure.With increasing immersion time,the total strain energy,the elastic strain energy and the dissipated strain energy of the specimen decreased,and the energy required for specimen failure reduced.The dissipation ratio of the specimens decreased by 54.38％-57.56％with increasing normal stress at the same immersion time.The increase of normal stress raised the energy storage capacity in the specimen,as well as the input external energy required for fracture development,thus enhancing the bearing performance of the structure.According to the shear mechanical behaviors of the composite specimens,a shear model of soft rock-grout structures under different immersion times and normal stresses was established.
rock mechanicsstress levelsoft rockrock-grout composite structuretriaxial shear testenergy evolution
NETL
NSTL
万方数据
