Papers by Author: Xun Shan

Abstract: In this article, we prepare the physical model with the high density epoxy resin and different sizes of coin shaped silicone pieces which can simulate the directional arrangement of fracture medium. On the basis of this, we analyze the influences of fracture angle on the ultrasonic compressional wave velocity using the pulse transmission method and compare the experimental results with the Hudson effective medium model. The experimental results show that, velocity decreases linearly with the increase of fracture angle within the interval of [0°~90°]. In a similar aspect ratio and same angle case, the increase of fracture porosity will result in the decrease of the velocity which is weakened by the increase of fracture porosity. At high fracture porosity, fracture angle becomes the important influence factor on the velocity changing. The calculation results of the Hudson model have a small deviation which is less than 5% compared with the experimental results but show a difference in different angle interval. The combination of the two methods will provide a certain basis for the indoor experiment and the measurement of the velocity in field.

Abstract: Crack universally existing underground is an important kind of pores. In order to study the elastic wave propagation in fractured medium through experiment, a new method to make artificial core with certain cracks using oil well cement and camphor sheet or thin steel sheet is put forward. Geometric parameters of the crack, such as shape, size and aspect ratio, are approximately equal to that of camphor sheet or thin steel sheet. Using the thin steel sheet to make crack can be more easy and accurate to control the crack angle than using camphor sheet. The crack opening scales at millimeters. The aspect ratio of cracks formed by camphor sheet ranges from 1.4 to 8, and aspect ratio of cracks formed by thin steel sheet ranges from 2.5 to 70. This method is proved simple and feasible by experiment practice, which can provide artificial cores with certain crack for acoustic wave propagation study.