Pan Yishan

The study of chamber rockburst by the CUSP model of catastrophe theory

By means of CUSP model of catastrophe theory, this paper has studied the physics process of rockburst occurred on circular chamber. The present paper has not only described the instability process of rockburst more deeply, but also got the critical depth of plastic softening area of chamber that is valuable in the controlling engineering of rockburst. The chamber displacement jump and energy liberation have been derived. The influence of rock parameters on the rockburst has been discussed.

Effect of relative stress on post-peak uniaxial compression fracture energy of concrete

Fracture energy in strain softening regime was investigated analytically by considering microstructures interaction and interplay. Based on gradient-dependent plasticity, the thickness of localized band was determined completely and strictly by characteristic length in relation to average grain diameter. After obtaining the plastic shear displacement of the band, the formula on axial response of concrete was proposed and the analytical post-peak fracture energy was deduced. A comparison between present theoretical results and earlier experimental results was carried out and the analytical result is reasonable and has a plausible foundation as considering the localized failure theoretically. Decreasing the relative stress leads to increasing the fracture energy non-linearly. The large the shear elastic modulus and shear softening modulus, the lower the post-peak fracture energy. A larger fracture energy is caused by a larger thickness of shear band or a larger characteristic length of concrete material. If the inclination angle of the shear band and the compressive strength are not concerned with structural size of specimen, the post-peak fracture energy is size independent.

Analyse of pulse wave propagation in arteries

Based upon the blood vessel of being regarded as the elasticity tube, and that the tissue restricts the blood vessel wall, the rule of pulse wave propagation in blood vessel was studied. The viscosity of blood, the elastic modulus of blood vessel, the radius of tube that influenced the pulse wave propagation were analyzed. Comparing the result that considered the viscosity of blood with another result that did not consider the viscosity of blood, we finally discover that the viscosity of blood that influences the pulse wave propagation can not be neglected; and with the accretion of the elastic modulus the speed of propagation augments and the press value of blood stream heightens; when diameter of blood vessel reduces, the press of blood stream also heightens and the speed of pulse wave also augments. These results will contribute to making use of the information of pulse wave to analyse and auxiliarily diagnose some causes of human disease.

Experimental Study on Zonal Disintegration of some kinds of Layered Similar Material Model

Summary It is known from experimental studies that a zonal periodic structure in the form of alternated regions of fractured and relatively intact rock appears around rock workings. It is impossible to describe the occurrence of such a structure on the basis of the classical continuum model, so it attracted the research’s wide attention. In order to know the crack distribution and its change along the axial direction, and this phenomenon may take place in which kinds of material, four kinds of layered similar materials blocks are used to establish a barrel model. The crack distribution and its change along the axial direction of the barrel model are observed experimentally. It is found out that there are some common characteristics when they are under high axial and confining pressure , but they also have their own features .The law of deformation and failure can be observed clearly if the surface is covered with speckle.