Study On Mechanical Properties And Failure Characteristics Of Layered Composite Rock Under Acid Environment

The use of underground space has been paid more and more attention with the development of our country's society and economy.The diversity and complexity of rock mass performance in deep underground engineering is an important factor restricting the construction of underground engineering.The instability of the interface layer has brought great difficulties and challenges to the research work and the practical engineering,especially the layered composite rock mass in the deep underground complex environment.In this paper,different types of layered composite rock specimens are made through the processing of the raw materials of the deep rock mass.The influence of deep underground acid environment and different angle of interface layer is considered.And the experimental study on the mechanical properties and failure mechanism of layered composite rocks is carried out.The research work mainly includes the following contents:(1)Red sandstone,green sandstone and marble are selected as initial rock samples.And layered composite rock samples with different types and different interface dip angles have been made.The maintenance test of the simulated deep underground environment under the condition of pH=2 and pH=4 acid solution has been carried out.The acid environment has a certain influence on the characterization and quality of different rock samples.(2)The uniaxial compression test of the cured rock samples was carried out,and the uniaxial compression strength and load displacement curves are obtained.The analysis shows that the acid solution can obviously reduce the compressive strength of the rock samples,and the greater the acid strength,the greater the compressive strength decreases.When the inclination angle of the interface layer is large,the influence of the acid environment is reduced.The uniaxial compressive strength of the rock sample is greatly reduced by the influence of the interface dip angle,and the failure mode has been changed.(3)The dynamic impact test of the cured rock samples was carried out,and the dynamic compressive strength and the stress-strain curve were obtained.The acid solution can reduce its dynamic compressive strength when the dip angle of the interface layer is small.It is the same as the static test when the dip angle reaches a certain range.The effect of the acid environment is greatly reduced,and the dynamic compressive strength is greatly reduced by the angle of the dip.The acid environment has the leading role when the angle continues to increase to reach the vertical.The dynamic compressive strength increases with the increase of the impact load.(4)The study shows that the dynamic failure modes of rock samples are different when the angle of the interface is different.The fracture of the rock specimen is broken through the interface layer when the interface layer is horizontal angle.The rock sample has produced shear failure in the crossing interface layer when the dip angle of the interface layer is 15 degrees.The rock specimen is broken along the interface layer when the inclination angle of the interface layer is diagonal.The rock specimen is split and broken along the interface layer when the dip angle of the interface layer is vertical.(5)The constitutive model of layered composite rock under dynamic impact is established based on a single rock dynamic constitutive model and experimental results.The effect of the dip angle of the interface layer is considered,and the curve of the model is in good agreement with the test result.