Numerical Simulation Of Jointed And Fractured Rock Masses Blasting

In recent decades, scholars at home and abroad have done a great quantity researches on stress wave propagating in rock mass, which have a certain breadth and depth. But the researches were mainly concentrative on homogenelty and intact rock. To the rock with joint and fissure, only theoretical study developed, lacking of its quantitative analysis. In nature, rock is in true triaxial stress state that most researches are limited to two dimensional analyses; there is less simulation on three-dimensional behavior of rock. There has vast original crack inside the natural rock, distributed randomly in the space. That is to say, certain degree damage has been existed in rock before it bearing external load. When it bears external load (such as blasting), original crack will interacted with blasting stress wave and forming scattered wave. And then, rock destroyed by the combined action of incident wave and scattered wave. In the former research people often ignore the effect of original crack, therefore, the result has some difference with actual inevitably.LS-DYNA combining discrete element method software 3DEC are used in the paper, referencing Zunyi new train station square controlled blasting engineering in Guizhou province, studies the blasting mechanism of closed macroscopic fractured rock, getting propagate law of explosive wave in multiterm fractures.3DEC is developed basing on UDEC that disposes discontinuous medium. It uses to simulate responses of discontinuous medium (such as joints and fractures, etc.) at the static load or dynamic load. The main research work and innovation achievements are as following:(1) Closed macro fractures hampers explosion wave propagation. Shown as simulation, the stress wave is not well-distributed in slope blasting and spreading toward free surface.(2) Number of closed macro fractures affects the explosion wave propagation. Comparing the intact model, two fractures divides the stress region as three parts and that of the intersect fractures is even dispersed.(3) The fractures affect the amplitude of minimum principal stress wave. When cracks exist, minimum principal stress reduces faster; it is dropped to 20% to the two parallel fractures and 30% to the crossed fractures.