Research Of Micro-and Meso-softening Mechanism Of Redbeds Soft Rock With Water

The redbeds soft rock is general softening for its complex composition and special structure, namely the ability of anti-weathering is weak, and soft rock is sensitive to water, and rock mass strength decreased when it interaction with water. The change of macro mechanical properties of rock is performance of the micro structure change, and the fundamental reason of the change of macro mechanical properties of rock is the micro structure change. The paper studies the structures of soft rock on different levels (macroscopic-structure, meso-structure, microstructure), which aims at investigating the effect of water and structure on the soft rock softening.(1) Through the literature review of redbeds soft rock, the structure characteristics of redbeds soft rock is summarized, which structure has levels of meaning and is similar, namely the dense structure, the directional structure, and the loosely structure.(2) Some experimental study on the redbeds soft rock is studied, such as disintegration test, strength attenuation test of redbeds soft rock, component loss test, destruction test of structural connections; The results show that the interaction between water and rock is related to PH, which makes a certain loss of material composition and chemical composition. The fundamental reason of the reduced physical and mechanical properties is the damage of structural connections.(3) The changes in the internal structure of the during uniaxial compression test is observed by the PFC2D numerical simulation software, which reproduce the evolution the process of micro-crack to macro-crack fracture during the uniaxial compression test. The interaction between water and rock is intensified with the increase of moisture content, and the uniaxial compressive strength of rock is reduced.(4) The damage effect of water on the redbeds soft rock structure is studied on different scales. The interaction between water and rock is a process of which the changes of microstructure lead to the changes of macroscopic mechanical properties. The interaction between water and rock leads to the difference between the deformation and the failure of rock, which is macroscopic and closely related to the change of microstructure.