Study On The Calculation Models Of Coseismic Displacement Field And Engineering Application

Co-seismic displacement refers to the ground deformation caused by fault dislocation in the earthquake,and the research of co-seismic displacement is of great significance for the earthquake-resistance design and earthquake damage prediction of geotechnical deformation,tunnels,bridges,and lifeline systems.By studying the empirical relationship and coseismic displacement calculation model,we can expect to find a coseismic displacement calculation model suitable for China's seismic region,which can provide a theoretical basis for the urgent that needs to solve the seismic design of cross-fault underground engineering.It mainly focuses on the following aspects: It has combed the commonly used empirical relationships and applicable scopes at home and abroad;It has combed the commonly used calculation models and applicable scopes at home and abroad,and initially explored the scope of application of the model;The co-seismic displacement calculation software has been developed,which simplifies the co-seismic displacement calculation process;The application of each model has been validated by the seismic parameters of the Wenchuan earthquake,and we applies the best applicability model to engineering calculations the results.Through the above several aspects,the following conclusions are drawn:(1)The relationship between magnitude and rupture length and fracture width in the Wells empirical relationship can be applied to earthquake areas in China including the Wenchuan earthquake;the regression relationship between magnitude and mean displacement can be estimated for pipeline and tunnel design.The total amount of displacement that can occur provides a reliable basis for seismic design.(2)Selecting the seismic events with detailed surface rupture information in the 21 st century in China,three types of calculation models were examined.The actual use effects were as follows: Lee's dmax(M)model,Chen Peishan model and Wells and Coppersmith model.Lee's dmax(M)model has good consistency with the measured results when the magnitude is not large.The exponential linear empirical formula given by the Wells model reflects the macroscopic statistics of historical earthquakes all over the world,and there are still large errors in calculating the specific earthquake cases.When using Chen Peishan's model,since the value of regional stress value ?0 has no actual record,it can only be derived from the empirical formula,resulting in a large deviation between the calculated results and the actual situation.In addition to this,the constant term of the Chen Peishan model is derived from an earthquake between the magnitude magnitudes of 4.9 and 7.2.When the magnitude exceeds 7.2,the model constant term is no longer applicable,so the model cannot calculate coseismic well.(3)Comparing the GPS co-seismic displacement observation data of Wenchuan earthquake with the calculation results of Chen Peishan model,dmax(M)model and Okada calculation model,it was found that the Okada model can well fit the Wenchuan earthquake coseismic displacement field.Chen Peishan's model has serious limitations due to the use of the fitting experience parameters,and it does not have a good inversion of the coseismic field of the Wenchuan earthquake.Due to the uncertainty of the site conditions,the dmax(M)model causes large fluctuations in the calculation results.(4)The Okada model was applied to the seismic safety assessment of a certain tunnel in Yunnan.Through computational analysis,reliable design parameters were provided for the coseismic displacement seismic design of the tunnel.