Study On The Deformation Mechanism Of The Hinterland Of The Longmen Mountain Foreland Basin Induced By The Wenchuan Earthquake

Faults play a role in promoting the evolution of organic matter,providing oil and gas accumulation storage sites,improving reservoir performance,moving oil and gas,and connecting traps during the formation of oil and gas reservoirs.Studying the generation and development mechanisms of faults for the development and utilization of oil and gas reservoir resources is of great significance.It has been confirmed that faults will cause tectonic earthquakes in the process of formation,and it is still a question whether earthquakes will cause the occurrence and secondary development of rock fractures such as new fault folds.The"512"Wenchuan earthquake in 2008 was the result of the Indian Ocean plate subducting into the Asia-Europe plate,which caused the rapid uplift of the Qinghai-Tibet Plateau.Related research found that it caused the rupture of the rocky stratum of the Longmen Mountain foreland basin in the near field to the midfield with deformation.For this reason,based on the related research of elastic wave dynamics,blasting mechanics analysis and rock fracture criterion,and the seismic wave data of seismic stations,an efficient and reasonable numerical simulation mechanism is designed to study deformation mechanism of the front of Longmen Mountain under the influence of Wenchuan earthquake.The numerical value of the stress influence of the Wenchuan earthquake and the displacement deformation of the hinterland of the Longmen Mountain foreland basin under the influence of the earthquake are calculated.The main research contents and results of the paper are as follows:1.Based on the study of elastic wave dynamics theory and the effect of blasting seismic stress,a computer system for the stress effect of seismic waves has been developed.To a certain extent,it is possible to calculate and simulate the stress transmitted by seismic waves on isotropic rock layers and layers,and according to the distance from the source.The calculation of stress attenuation is carried out at a distance near and near as simple as possible and errors are minimized on the basis of achievable.2.The strata of the Longmen Mountain foreland basin are layered according to their composition and age,and the physical and mechanical parameters of each layer are averaged.Static information such as surrounding rock pressure and friction coefficient of each layer are calculated.The model is constructed using FLAC^3Dsoftware.Allocate monitoring points to monitor the stress and displacement of the fault model body before and after the earthquake wave stress affects it.Load static information such as confining pressure and friction of each layer into the model and perform initial calculations to obtain the static stress and displacement of the fault model.Then the calculated seismic wave dynamic information is applied to the statically calculated fault model body.After damping and fixed boundary conditions are applied,the dynamic calculation is performed to obtain the stress and displacement of the fault model under the influence of seismic wave dynamics.3.Compare the stress values under the influence of static and seismic wave dynamics,analyze the critical conditions of failure with the change of principal stress,draw the molar stress circle,and get the critical stress values of model failure under the influence of seismic waves.According to the monitoring information before and after the monitoring point,the damage of each location in the destination layer is analyzed,the time range of the occurrence of the damage,the destructive displacement and deformation after the influence of the seismic wave stress.It was confirmed that under the influence of the Wenchuan earthquake,structural damage and fault deformation occurred in the guts of the Longmen Mountain foreland basin,and the relevant information such as the seismic stress value and the ground damage displacement value of the formation were calculated.