Cement mortar specimens are used to simulate the fracture of rock material under uniaxial compression test, using the ultrasonic instrument measurement test process, the waveform and wave velocity results along with t...Cement mortar specimens are used to simulate the fracture of rock material under uniaxial compression test, using the ultrasonic instrument measurement test process, the waveform and wave velocity results along with the change of specimen fracture extension are obtained. Experimental results show that at 0 MPa, there are micro-defects in the specimen, leading to the irregular change of the waveform of the measuring points 4# and 5#;At 1 - 4 MPa, there is no crack on the surface of the specimen, the waveform of ultrasonic wave is stable, and the velocity of each point increases with the increase of the strain, but the measuring point increases the wave velocity when the load is applied;When the specimen surface cracks, expect the waveform of measuring point 4# and 5# change in irregularities, the measuring point 2# waveform also changes irregularly and measuring point of the wave velocity has decreased;At the crack propagation stage, ultrasonic wave also changes irregularly along with the expansion of crack, wave velocity with the increase of the strain is also obvious downward trend;When the crack penetrates the whole specimen, the waveform of each measuring point changes abnormally, the continuity is bad, the waveform is irregular and the measured wave velocity is low.展开更多
A genetic algorithm of body waveform inversion is presented for better understanding of crustal and upper mantle structures with deep seismic sounding （DSS） waveform data. General reflection and transmission synthet...A genetic algorithm of body waveform inversion is presented for better understanding of crustal and upper mantle structures with deep seismic sounding （DSS） waveform data. General reflection and transmission synthetic seismogram algorithm, which is capable of calculating the response of thin alternating high and low velocity layers, is applied as a solution for forward modeling, and the genetic algorithm is used to find the optimal solution of the inverse problem. Numerical tests suggest that the method has the capability of resolving low-velocity layers, thin alternating high and low velocity layers, and noise suppression. Waveform inversion using P-wave records from Zeku, Xiahe and Lintao shots in the seismic wide-angle reflection/refraction survey along northeastern Qinghai-Xizang （Tibeteau） Plateau has revealed fine structures of the bottom of the upper crust and alternating layers in the middle/lower crust and topmost upper mantle.展开更多
文摘Cement mortar specimens are used to simulate the fracture of rock material under uniaxial compression test, using the ultrasonic instrument measurement test process, the waveform and wave velocity results along with the change of specimen fracture extension are obtained. Experimental results show that at 0 MPa, there are micro-defects in the specimen, leading to the irregular change of the waveform of the measuring points 4# and 5#;At 1 - 4 MPa, there is no crack on the surface of the specimen, the waveform of ultrasonic wave is stable, and the velocity of each point increases with the increase of the strain, but the measuring point increases the wave velocity when the load is applied;When the specimen surface cracks, expect the waveform of measuring point 4# and 5# change in irregularities, the measuring point 2# waveform also changes irregularly and measuring point of the wave velocity has decreased;At the crack propagation stage, ultrasonic wave also changes irregularly along with the expansion of crack, wave velocity with the increase of the strain is also obvious downward trend;When the crack penetrates the whole specimen, the waveform of each measuring point changes abnormally, the continuity is bad, the waveform is irregular and the measured wave velocity is low.
基金National Nature Science Foundation of China (40334040) & Joint Seismological foundation of CEA (101026)
文摘A genetic algorithm of body waveform inversion is presented for better understanding of crustal and upper mantle structures with deep seismic sounding （DSS） waveform data. General reflection and transmission synthetic seismogram algorithm, which is capable of calculating the response of thin alternating high and low velocity layers, is applied as a solution for forward modeling, and the genetic algorithm is used to find the optimal solution of the inverse problem. Numerical tests suggest that the method has the capability of resolving low-velocity layers, thin alternating high and low velocity layers, and noise suppression. Waveform inversion using P-wave records from Zeku, Xiahe and Lintao shots in the seismic wide-angle reflection/refraction survey along northeastern Qinghai-Xizang （Tibeteau） Plateau has revealed fine structures of the bottom of the upper crust and alternating layers in the middle/lower crust and topmost upper mantle.
