Study On The Mechanism And Microscopic Characteristics Of Red Layer Disintegration In Lanzhou

Red sandstone is a kind of sandstone with special properties,which quickly disintegrates and softens when it encounters water.In this paper,combined with the regional geological structure of the Lanzhou Metro,the microstructure characteristics of rock samples with different water content and disintegration at different times were systematically tested,and the pore area,pore circumference and pores of red sandstone under different test conditions were observed.The rate of change of the rate,in addition,through the experimental observation of the rock sample microstructure characteristics change,analyze the reasons for the rapid decrease of the foundation strength.This paper mainly studies the hydraulic characteristics of red sandstone.Through field investigation and laboratory experiments,it is concluded that the compressive strength of red sandstone drops sharply after the water-rock chemical reaction occurs.Scanning electron microscopy and X-ray diffraction tests were carried out on red sandstones with different water content and different disintegration times.Image J software and X'Pert HighScore Plus were used to calculate the porosity,pore area and pore circumference under different test conditions,and Measure the mineral composition and its content.Quantitative analysis of parallel samples was carried out to obtain the red sandstone under different water cuts and the change in pores and the content of its mineral composition under different disintegration time.Finally,the fractal theory is used to analyze the red sandstone under two different test conditions,and the mechanism of rapid disintegration of the red sandstone when it meets water is discussed.Experimental studies have shown that the reduction of the uniaxial compressive strength of red sandstone is closely related to the change of microstructure.The dissolution and reaction of the aqueous solution to minerals have changed the mineral composition of the rock and caused a sharp drop in strength.The water-rock chemical reaction is a dynamic time-dependent reaction.The adsorption and redox reactions are accompanied by the whole process of red sandstone disintegration.During the reaction,the internal crystal lattice of the mineral is destroyed,and the energy is continuously released.With prolongation,the chemical reaction becomes more intense.Water-rock interaction is one of the factors that affect the rapid disintegration of red sandstone when it encounters water.When studying the lithology and disintegration mechanism of large-scale red sandstone,the formation of geological structures and historical changes in this area also need to be considered.