Study On The Mechanism Of Water Damage And Energy Dissipation Of Red Sandstone In Lanzhou

Rock,as a complex geological structure,has a large number of fine and microscopic defects randomly distributed inside.It is a solid mineral or a mixture of multiple minerals,and is widely used in various construction projects.As a kind of easily disintegrating rock,red sandstone has poor engineering characteristics after encountering water.The Lanzhou subway is built in red sandstone layers.Because of the shallow groundwater depth,the red sandstones are all strongly weathered sandstones.During the construction of the subway,a large amount of strongly weathered sandstone disintegrated when it meets with water,the nature of the project was weakened,the bearing capacity was reduced,and the bearing capacity was partially or completely lost,resulting in slow construction and longer construction period.In order to study the softening characteristics of red sandstone when it meets with water,this dissertation takes the red sandstone sampled at the Lanzhou subway construction site as the research object,and focuses on the strength damage and energy dissipation of red sandstone with different water content in the process of deformation and failure.The combination of engineering test and theoretical analysis is used to deeply study the strength damage and energy dissipation law of red sandstone when it encounters water.The main conclusions obtained are as follows:(1)Make specimens with different moisture content and perform uniaxial compression tests,and obtain the stress-strain curve of the whole process.It is concluded that with the increase of moisture content,the peak strength of the red sandstone sample gradually decreases,the peak strain gradually increases,and the elastic modulus reduce.During the compression process of red sandstone with different water content,the influence of water on each stage is different.The influence of water gradually increases as the deformation becomes larger.(2)According to the relationship between the elastic modulus and the water content of the rock,the damage constitutive model of red sandstone in different water-bearing states under the action of water is deduced and verified by comparison with the actual curve.The theoretical results are basically in good agreement with the experimental results.(3)From the energy level,further analyze the law of energy dissipation in the deformation and failure process of red sandstone after encountering water.Calculate and analyze the change and rate of change of various energy in the stress-strain process,and based on energy analysis,study the change law of the dissipated energy of red sandstone over time.At the same time,the energy damage variable is introduced,the energy damage law of the red sandstone when it meets with water is discussed and analyzed,and the relationship between the intensity and the energy damage variable is established.This dissertation studies the strength damage and energy dissipation laws of red sandstone when it encounters water,and the conclusions of the research have certain reference value for analyzing the degradation of red sandstone when encountering water and the in-depth study of the stability of the Lanzhou subway foundation.