Geology topics

Z. Shi

Publications and source records attributed to Z. Shi.

3 recordsLinked to original sources

USGS2004

Investigation of the low-depression velocity layer in desert area by multichannel analysis of surface-wave method

The multichannel analysis of surface-wave method (MASW) is a newly development method. The method has been employed in various applications in environmental and engineering geophysics overseas. However, It can only be found a few case studies in China. Most importantly, there is no application of the MASW in desert area in China or abroad. We present a case study of investigating the low-depression velocity in Temple of North Taba Area in Erdos Basin. The MASW method successfully defined the low-depression velocity layer in the desert area. Comparing results obtained by the MASW method with results by refraction seismic method, we discussed efficiency and simplicity of applying the MASW method in the desert area. It is proved that the maximum investigation depth can reach 60m in the study area when the acquisition and procession parameters are carefully chosen. The MASW method can remedy the incompetence of the refraction method and the micro-seismograph log method in low-depression velocity layer's investigation. The MASW method is also a powerful tool in investigation of near-surface complicated materials and possesses many unique advantages.

Conference Paper↗

USGS2004

Study on geophone coupling and attenuating compensatory of low-depression velocity layer in desert area

In a desert area, it is difficult to couple geophones with dry sands. A low and depression velocity layer can seriously attenuate high frequency components of seismic data. Therefore, resolution and signal-to-noise (S/N) ratio of seismic data deteriorate. To enhance resolution and S/N ratio of seismic data, we designed a coupling compensatory inverse filter by using the single trace seismic data from Seismic Wave Detect System (SWDS) and common receivers on equal conditions. We designed an attenuating compensatory inverse filter by using seismic data from a microseismogram log. At last, in order to convert a shot gather from common receivers to a shot gather from SWDS, we applied the coupling compensatory inverse filter to the shot gather from common receivers. And then we applied the attenuating compensatory inverse filter to the coupling stacked seismic data to increase its resolution and S/N ratio. The results show that the resolution of seismic data from common receivers after processing by using the coupling compensatory inverse filter is nearly comparable with that of data from SWDS. It is also found that the resolution and S/N ratio have been enhanced after the use of attenuating compensatory inverse filter. From the results, we can conclude that the filters can compensate high frequencies of seismic data. Moreover, the low frequency changed nearly.

Conference Paper↗

USGS2003

Settling velocities of fine suspended particles in the Changjiang Estuary, China

Point-sampled suspended sediment concentration profiles (grain size largely < 32 ??m) were measured in August 1978, April 1990, and May 1990 in the Changjiang Estuary. They were selectively fit with the Rouse equation in order to calculate the median settling velocities ws,50 of fine suspended particles in the Changjiang Estuary, East China Sea. Calculated settling velocities ranged from 0.4 to 4.1 mm s-1. Furthermore, ws values increased with the mean concentration C?? of sediment in suspension. The best-fit equation for the field settling velocity of fine particles in the Changjiang Estuary can be expressed by the power law: ws = 2.37 C??0.84 (r2 < 0.3). ?? 2003 Elsevier Ltd. All rights reserved.

Journal of Asian Earth Sciences↗