Study On Deformation And Failure Law Of Anchor Body Under Deviatoric Stress State

To investigate the deformation and damage law of anchor solid under partial stress,this thesis investigates the damage form of anchor unit body under partial stress based on mechanical property tests,physical tests,numerical simulations,and engineering practice.The internal fracture development law of the anchorage unit body is analyzed from multiple perspectives.The main research contents of the thesis are as follows:(1)Using similar simulation means,suitable rock-like materials and anchor-like materials are selected.The basic mechanical tests were carried out to obtain the parameters such as tensile strength,compressive strength,cohesion,and internal friction angle of rock-like materials,and yield load and breaking load of anchor-like materials,which provide support for the later tests.(2)The whole process of damage of each unit body under biaxial partial stress loading and triaxial partial stress loading was studied.The change law of the damage load under different partial stresses was obtained.The anchorage can effectively improve the bearing capacity of the unit,the anchorage length is proportional to the bearing capacity,and the internal space crack affects the overall bearing capacity,and provides space for the internal damage of the unit.(3)The internal acoustic emission characteristics of the unit body under a partial stress state are analyzed.The acoustic emission signal sources during the loading process are mainly divided into two categories,the compression density of the internal pores at the beginning of loading and the microfractures generated by the internal slip of the specimen near the peak load.The acoustic emission characteristics under partial stress are divided into three stages: compression-density stage,stabilization stage,and damage stage,and the growth trend of the accumulated acoustic emission signal counts show "fast-slow-fast".In general,the acoustic emission signal of unit tension rupture is more in the partial stress state,and the acoustic emission signal changes to shear rupture more with the increase of anchorage length.(4)The macroscopic damage law of the unit body under partial stress is summarized.In general,the unit body is prone to tensile damage at the hollow surface under biaxial partial stress loading,and shear damage of "inverted V-shape" occurs internally;under triaxial loading,the damage characteristics are complex,with shear damage as the main damage,and more tensile cracks are generated.The anchorage unit body is mainly damaged by shear under biaxial partial stress loading,showing "N-shaped".Due to the influence of anchorage,the tensile strength of the specimen surface is increased to limit the tensile damage at the hollow surface.Under triaxial loading,the damage form of the specimen is complex,with shear damage as the main damage surface,and the damage is mainly caused by small cracks due to the small damage space of the three-way load deformation.(5)The PFC-FLAC coupling model was constructed to carry out the simulation analysis under a partial stress state,and the simulation results were similar to the test pattern.After the bias stress-strain curve grows linearly to the damage load,the biaxial bias stress unloads quickly and the triaxial bias stress has a certain residual strength.And the damage load under triaxial partial stress is increased by about 40%compared with the biaxial partial stress state.The macroscopic damage law of the unit body is explained from the microscopic point of view.The inter-particle damage within the model is mostly tensile,and the tensile damage between the particles generates a misalignment between the particles due to the load,forming an oblique shear surface,and the particles move along the oblique shear surface to form a macroscopic shear damage surface.(6)For the problem of deformation of the surrounding rocks of the transportation road at the 21316 working faces of the Xieqiao mine,the practice of full-length anchorage support with slurry injection at the gang section was carried out.Within the construction range of the roadway,the anchor support resistance is stable,the deformation of the roadway surrounding rock is reduced within the same time,the deformation is controlled within 120 mm.The full-length anchoring solution of gang grouting effectively seals the internal fissures of the roadway surrounding rock,reduces the internal damage space,weakens the large deformation of the roadway gang,and realizes the long-term stability of the surrounding rock of the deep roadway.At the same time,it provides practical experience for the support design of the same type of roadway.This thesis has 72 diagrams,9 tables,and 83 references.