Study On Acoustic And Electric Effects Of Rocks In Different Water-bearing States Under Dynamic And Static Loads

The mining depth of modern rock engineering is continuously increasing.Underground rock masses will be affected by dynamic loads such as excavation disturbances and blasting while being subjected to horizontal and vertical high ground static stresses,and the rock mass of underground engineering has different The mechanical properties of the water-bearing state are very different.It is of great guiding significance for the rock engineering to use the acousto-electric nondestructive dynamic detection system to study the changing law of the mechanical properties of rocks with different water-bearing states.In this paper,studies on acoustic emission characteristics and electromagnetic radiation characteristics of sandstone failure in different water-containing states under static load and dynamic load are carried out.The main contents and conclusions are as follows:(1)Using rock fracture mechanics and one-dimensional wave theory,the crack propagation relationship of brittle rock under load and the relationship between the internal stress and strain of rock under stress wave are analyzed.The relationship between crack growth and acoustic emission parameters and electromagnetic radiation parameters is analyzed using crack expansion theory,and acoustic emission parameters are obtained The electromagnetic radiation parameters are related to the rock elastic modulus,Poisson’s ratio,compressive strength,and the properties of the material itself.(2)Using the RMT-150 C mechanical testing machine and acoustic and electrical acquisition system,a sandstone failure test under different water conditions under uniaxial compression was carried out.By analyzing the mechanical properties of the rock and the characteristics of acoustic and electrical signals,the following conclusions were obtained: The compressive strength and elastic modulus of rocks will increase,and dry rocks are mainly shear breaking,while rocks in saturated samples are mainly tensile failure;acoustic emission signals and electromagnetic radiation of sandstones in different water-containing states There are some differences in the signal during the loading process,but both of them are in good agreement with the rock stress-strain curve.(3)Using the SHPB test system and the acoustic and electrical acquisition system,failure tests of sandstones in different water-bearing states under dynamic loading were carried out.By analyzing the mechanical properties of rocks and the characteristics of acoustic and electrical signals,the following conclusions wereobtained: when the sample strain rates were the same,the dynamic resistance of the samples The compressive strength increases with decreasing water content;when the sample has the same water content,the dynamic compressive strength of the water sample increases with increasing strain rate.Under the impact load,the acoustic emission signal is concentrated,and it will suddenly increase from a small value to the highest value near the peak intensity of the rock and then decrease rapidly.The peak value of the dynamic emission acoustic emission parameter can represent the ability of the rock to resist deformation;the electromagnetic radiation signal is relatively active under the impact load And the dispersion;the difference between the two signals under dynamic load has a certain relationship with the relative position of the sensor and the sample.(4)Using different physical and mechanical parameters,the numerical simulation software RFPA was used to simulate the internal crack propagation relationship and acoustic emission law of different water-bearing models under static and dynamic load stress waves.The results show that: under static load,the higher the water content of the model,the faster the model’s failure rate,and the lower the acoustic emission energy generated by its failure;under the same dynamic load stress wave,the higher the model’s water content,the more the model’s failure rate Slowness,which is related to the inability of the stress wave to propagate quickly in model elements with low mechanical properties;under the same water state,the larger the stress amplitude of the dynamic load stress wave,the faster the model is destroyed,and the more severe the damage;The stress diagrams under acoustic and dynamic loading show good agreement with the acoustic emission diagrams.