Simulation Of Near-fault Ground Motion Considering Sedimentary Basin

Near-fault earthquakes can cause serious earthquake disasters,causing huge casualties and property losses to human society.Seismic observation records show that the sedimentary basins will amplify the seismic waves in the basin,resulting in an increase in earthquake disasters in the basin.At present,there are few studies on ground motions considering both near faults and sedimentary basins,so the research in this thesis has certain significance.In this thesis,the finite fault source model theory and the wave simulation method are used to simulate the ground motion of the sedimentary basin under the near fault.The specific research contents and results are as follows:(1)The ABAQUS software is used to simulate the propagation of waves in a rock-soil medium,applying an infinite-element artificial boundary and simulating the propagation of waves in a semi-infinite space medium.(2)By comparing the peak ground acceleration(PGA for short),peak ground velocity(PGV for short)and peak ground displacement(PGD for short)of the basin model and the bedrock model,the conclusions are as follows:? Under the action of near faults,the sedimentary basins have amplifying effect on PGA,PGV and PGD.The horizontal PGA has a strong amplification at the edge of the basin,and the amplification factor is 2?3.The horizontal PGV has a strong amplification at the edge of the basin,and the amplification factor is 2?2.5.? When the depth of the basin is 0.6km,the basin has the strongest amplification effect on the horizontal PGA near the center of the basin and the basin inclination angle is 45°,and the amplification factor is about 2.5.?When the depth of the basin is 1.2km,near the center of the basin,the basin has the strongest amplification effect on the horizontal PGA with a dip angle of 45°,and the amplification factor is about 2.5.Near the edge of the basin,the basin amplifies the horizontal PGA and horizontal PGV with the basin.The inclination increases and increases.(3)A two-dimensional model of the Weihe Basin was established,and appropriate faults were selected as the source to simulate the 6.5-magnitude earthquake that may occur in the future.The results are as follows:?The PGA,PGV and PGD of the central part of the Weihe Basin are larger.At the edge of the south and north basins,the ground motion of the southern margin of the basin is stronger than that of the north,and the horizontal PGA of the southern margin of the basin is about 0.2 m/s2.The horizontal PGA is about 0.1 m/s2.?The ground motion near the surface rupture point of the Weihe Basin earthquake is stronger than that of the surrounding area.?There is an upper and lower disk effect in the range of 20 km from the surface rupture point,and there is a velocity pulse in the horizontal direction near the epicenter position.