Self-regulating roof-bolting with the rock pressure energy use

The perspective of discovery of zonal disintegration phenomenon of rocks around underground mine workings is analyzed. The methodological stages for research of this phenomenon are shown. The physics of zonal disintegration of rocks around underground mine workings is disclosed. There are described the possibilities of advanced entropy method and developed energy method that allow to investigate a phenomenon of zonal capsulation of underground mine workings. The sequence of research of this phenomenon parameters is presented. The order of choice of stable shape and resource-saving support in underground mine workings is substantiated, for the deep horizons of the Kryvorizkyi Iron-Ore Basin mines. The method of parameters calculation of self-regulating roof-bolting in underground mine workings is substantiated, which allows to use the rock pressure energy. The design of a self-regulating roof-bolting is developed, which allows applying metal, polymer and rope bolts. The economic efficiency of rock pressure energy usage is substantiated in case of support setting at great depths in underground mine workings.

Numerical Simulation of Zonal Disintegration of the Surrounding Rock Masses Around a Deep Circular Tunnel Under Dynamic Unloading

A new numerical method, which is called the General Particle Dynamics (GPD) method, is proposed to investigate the zonal disintegration mechanism of isotropic rock masses around a deep circular tunnel subjected to dynamic unloading as well as the stress distributions. A constitutive model based on the GPD method is developed to simulate the zonal disintegration phenomenon in deep rock masses. The number and size of fractured and nonfractured zones are determined using the nonlinear unified strength criterion. It is shown from the numerical results that the dynamic loads and high in situ stress are two dominant factors for the occurrence of zonal disintegration.

Numerical Simulation on Zonal Disintegration in Deep Surrounding Rock Mass

Zonal disintegration have been discovered in many underground tunnels with the increasing of embedded depth. The formation mechanism of such phenomenon is difficult to explain under the framework of traditional rock mechanics, and the fractured shape and forming conditions are unclear. The numerical simulation was carried out to research the generating condition and forming process of zonal disintegration. Via comparing the results with the geomechanical model test, the zonal disintegration phenomenon was confirmed and its mechanism is revealed. It is found to be the result of circular fracture which develops within surrounding rock mass under the high geostress. The fractured shape of zonal disintegration was determined, and the radii of the fractured zones were found to fulfill the relationship of geometric progression. The numerical results were in accordance with the model test findings. The mechanism of the zonal disintegration was revealed by theoretical analysis based on fracture mechanics. The fractured zones are reportedly circular and concentric to the cavern. Each fracture zone ruptured at the elastic-plastic boundary of the surrounding rocks and then coalesced into the circular form. The geometric progression ratio was found to be related to the mechanical parameters and the ground stress of the surrounding rocks.

The Zonal Disintegration Law within Coal in Front of Working Face in Deep Coal Mine

The mining coal in the front of long wall face consists of elastic zone, plastic zone and fracture zone. Based on the research of zonaldisintegration of surrounding rock mass in deep tunnel, the zonal disintegration phenomenon of deep coal mine was analyzed by using the theoretical analysis method. On the basis of the Griffith theory, the internal and external boundary formulas of fracture zone and the mechanical criteria of zonal disintegration were obtained. The research shows that the essence of zonal disintegration is the tensile failure and brittle tension crack failure under the abutment pressure, the main influence factors of the width variation of fracture zone are original rock stress and un-axial tensile strength of coal.

Numerical Simulation on Supporting of Deep Surrounding Rock with Zonal Disintegration Tendency

In order to study the supporting of deep surrounding rock with zonal disintegration tendency, the zonal disintegration phenomenon of deep surrounding rock under three supporting forms is analyzed by the ABAQUS finite element software in this paper, and three supporting forms are un-supporting, bolting and grouting, and combined “Bolting and grouting plus Anchor rope” supporting. The results show that the different effects to zonal disintegration under different supporting forms will occur. Supporting can help to restrain the zonal disintegration of the reinforcement part advantageously, and also lower rupture degree of zonal disintegration and reduce the size of rupture zone. Meanwhile, the stability of surrounding rock is improved. But zonal disintegration may occur outside reinforcement part under greater ground stress. The results are great importance to a better understanding of the deep roadway supporting.