Experimental study on the influence of different sampling methods on the stress-strain and strength characteristics of weathered and water rich sandstone

In order to explore the physical and mechanical properties of layered weathered sandstone in a water rich environment, the authors obtained layered sandstone from the tunnel excavation section. Firstly, the physical properties and chemical composition were tested, and then uniaxial tests were conducted on sandstone, in which the loading direction was divided into perpendicular to the specimen bedding, parallel to the specimen bedding, and at a 45 ° angle to the specimen bedding. The uniaxial test results show that the stress-strain curve of sandstone is strain softening type. The uniaxial compressive strength of sandstone is between 2.18 MPa and 28.123 MPa, the residual strength is between 0.122 MPa and 24.284 MPa, the elastic modulus is between 5.843 MPa and 49.45 MPa, the Poisson’s ratio is between 0.303 and 0.484, and the softening coefficient of rock is between 0.15 and 0.20. The uniaxial compressive strength of sandstone samples subjected to blasting disturbance is 38% of that without blasting disturbance, and the elastic modulus is 30% of that without blasting disturbance. The axial and radial strains of sandstone samples significantly increased after blasting disturbance. Blasting significantly reduces the uniaxial compressive strength and elastic modulus of the sample. The uniaxial strength of sandstone decreases exponentially with increasing water content.