Study On The Deformation Failure Mechanism And Support Technology Of The Thick Mudstone Roof Roadway Surrounding Rock

At present,The groundwater is becoming one of the important factors affecting the stability of the roadway surrounding rock with the depth of coal mining is more and more deep,the roadway surrounding stress field and displacement field are always affected by aquifer.Through field investigation,the factors causing the deformation and failure of the roadway surrounding rock are analyzed,then the theoretical analysis and numerical simulation are combined,the deformation and failure mechanism of roadway surrounding rock under the effect of aquifer are analyzed.By assuming that the rock is homogeneous and isotropic continuous infiltration medium,the original rock stress is isotropic,the main seepage mainly in the direction of radial flow,liquid is Newton fluid of phase and incompressible,the penetration process accords with Darcy's law.The modified Mohr-Coulomb yield criteria by making effective stress replace total stress are applied,surrounding rock strain softening model and swelling fracture model are combined with seepage action,area coverage of circular roadway surrounding rock deformation failure is solved,then the radius and displacement of each region after roadway surrounding rock deformation failure are derived.Through the example analysis,the relationship between the roadway plastic zone under action of water and the supporting resistance,original osmotic pressure,strain softening and swelling fracture are concluded.Research shows that the results are more close to reality with the combination of seepage action,strain softening and swelling fracture characteristics,which the state of surrounding rock deformation failure is more real revealed.By appling the numerical simulation software flac3D,the change regulation of the stress field,displacement field and plastic zone are comparative analyzed whether subjected to the action of seepage or not,and discusses the shortcomings of the original supporting scheme for supporting effect under the action of seepage.At the same time,the supporting parameters are optimized and new supporting scheme is proposesed,finally the new supporting scheme is verified by numerical simulation and field test.The results show that the new supporting scheme can control the deformation of surrounding rock better than the original supporting scheme,which provides a reference for other similar engineering conditions supporting optimization design and safety evaluation.