Study On The Weakening Mechanism Of Interfacial Stability Of Mudstone And Anchor With Different Moisture Content

With the gradual reduction and depletion of shallow resources,resource development gradually develops deeper,and thousands of mines in China are increasing.Due to the particularity of the environment in which the deep rock mass is located and the complexity of the stress field,especially the deep soft mudstone under the environment of "three highs and one disturbance",it is easy to be destabilized and destabilized by the excavation or mining disturbances.In the gang accident,the stability of the mudstone anchor structure is particularly prominent.The analysis of mudstone anchor solid structure is based on the study of the surrounding rock of the draught shaft in the Wanfu Coal Mine of Yanzhou Coal Industry Co.,Ltd.During the construction process,due to factors such as rock seepage and borehole water accumulation,the mudstone is placed in a high humidity environment,combined with the water absorption weakening characteristics of the mudstone,the stability of the mudstone anchoring structure is weakened,which affects the partial failure of the anchor support.Or completely failed,which poses a great threat to the safe production of the mine.The basic rock properties of mudstone are analyzed by X-ray diffraction analysis,laboratory quality testing and uniaxial compression experiments.Determine the mineral composition and lithology of the mudstone,and characterize the mass water content,cracking characteristics of water and natural uniaxial compressive strength of the mudstone.Under the condition of humidity environment,the swelling characteristics of mudstone are measured and analyzed by means of constant temperature and humidity curing box curing.The swelling law of mudstone is summarized through size measurement and quality measurement at specific locations,and the relationship between its swelling strain and curing time is analyzed.The swelling laws of mudstones in different directions are different,with significant anisotropy,and the significant cracks,joints,and structural planes in the mudstone specimens directly affect the speed,expansion coefficient,and water content of the mudstone.The effect of water content on the uniaxial compressive strength of mudstone was tested by the uniaxial compression experiment in the laboratory.The test results show that the water content has a significant effect on the uniaxial compressive strength of the mudstone.As the water content increases,the uniaxial compressive strength of the mudstone decreases,showing a softening trend.When the mudstone reaches a saturated water content,the mudstone is cracked,the integrity of the mudstone is destroyed,and the bearing capacity is partially or completely lost.The failure mode of mudstone also changes with the increase of water content,and it gradually evolves from tensile failure to tensile shear failure.The mechanism of weakening the influence of water content on the stability of the interface between mudstone and anchoring agent under the humidity environment is simulated by PFC2 D.The numerical simulation parameters were checked through mudstone mechanical tests.The simulation results showed that: 1)With the increase of water content,the shear stress at the interface between mudstone and anchoring agent decreases and the shear strength decreases;2)The shear stress at the interface between mudstone and anchoring agent-The displacement curve tends to be gentle with the increase of water content,which conforms to the form of shear stress-displacement curve of weak materials.There are 28 pictures,7 tables,and 68 references in the paper.