The distributing rule of the third mine section ground stress value: while the mining depth is less than 780m, the level maximum principal stress is 15~19MPa, moreover the coal bed motherboard is bigger than roof, but around the fault the size and orientation of ground stress change a lot;

With the increase of mining depth in mine, the instability mechanics and control technology in deep mining and high pressure, soft rock, big deformation roadway are still crucial in underground engineering.

On the guantitative analysis to study the related parameters of roof consolidated by water injection in high seam and to simulate the regenerated roof in mining field with strength experiment of rock mechanics in house, the law among the cohesive strength, angle of internal friction, water ratio of the regenerated roof, the mining depth and other factors is obtained, and are determined the telated parameters,such as water injection height, water volume and thickness of consolidated roof.

The thesis analyzes the effect of the increase of mining depth on the floor heave, discusses the laws that gravity stress, tectonic stress, the strength of surrounding rock, terrestrial heat and imbibition water change with the increase of mining depth.

When mining depth is z_0, the surface subsidence unit basin expression is,The methods for calculating surface subsidence in semi-infinite and finite mining conditions are given.

The constant parameters of prediction model of mining subsidence for the 3_下 coal seam were solved by coupling the survey results of actual mining subsidence of two working faces with different mining depth and face length.

With the increase of mining depth and augmentation of gold requiring quantity by civil economy, it's more and more needed to exploit secure high-efficient mining methods.

In recent years, with the lengthways development of mining depth on coal seam, the geological condition is more and more complexity, and the problem of mining gas is more serious.

The height of the fractured zone decreases as the size of the outcrop pillar or mining depth decreases.

Below a mining depth of 300-500?m, this type passes over a short distance downwards into stibnite-poor gold-bearing veins.

With ramp and shaft entry, a main shop is required underground when the mean mining depth reaches 500m below surface.

With ramp entry, a satellite shop is required when the mean mining depth reaches 200m below surface.

This information will help with determining mining depth at the wetland site.

Ground control problems in subievel caving become evident as the rock pressure increases with depth. Recently, a finite element analysis of the stability problems of the sublevel caving method was completed by the authors. This paper summarizes the results of stress analysis in sublevel extraction drifts under different stress field conditions by using linear elastic and nonlinear elasto-plastic finite element modeling techniques. A critical stress concentration will occur in the uppermost sublevel drifts beneath...

Ground control problems in subievel caving become evident as the rock pressure increases with depth. Recently, a finite element analysis of the stability problems of the sublevel caving method was completed by the authors. This paper summarizes the results of stress analysis in sublevel extraction drifts under different stress field conditions by using linear elastic and nonlinear elasto-plastic finite element modeling techniques. A critical stress concentration will occur in the uppermost sublevel drifts beneath the caved area or blasted ore area. During the blasting and drawing cycle, a tensile and shear failure condition could develop in the central extraction drift when it would be mined last. Under a high horizontal stress field condition, almost all tensile stress in the back of the extraction drifts will be eliminated and only slight yield can be seen in the floor of the extraction drifts. Compared to the cases under the gravitational stress field condition, the total yielding zone will be grtly reduced because of the increase of horizontal confining stress with depth. However, it is predicted that the centre of each ore column side will experience excessive shear stress that probably will result in ore failure.The two major conclusions drawn from this study to improve the overall stability of sublevel caving are: (1) the width of extraction drifts must be carefully controlled and an appropriate stoping sequence selected; and (2) the sublevel caving method can be used in deep mining if the pillar width is increased correspondingly with mining depth.

In this paper the finite element method is used to analyze the effect of supporting parameters(including the elastic modulus of the fallen rock in the goaf, the setting load and rigidity of support) and the mining depth on roof behaviour in longwall face. The study indicates that elastic modulus of the fallen rock in the goaf, the rigidity and setting load of support are the major factors that affect roof behaviour. The optimal parameters of the hydraulic supports and the approaches for improving roof...

In this paper the finite element method is used to analyze the effect of supporting parameters(including the elastic modulus of the fallen rock in the goaf, the setting load and rigidity of support) and the mining depth on roof behaviour in longwall face. The study indicates that elastic modulus of the fallen rock in the goaf, the rigidity and setting load of support are the major factors that affect roof behaviour. The optimal parameters of the hydraulic supports and the approaches for improving roof control are also involved. It is pointed out that stress concentration in front roof is the main factor causing the roof failure. It is suggested that support with high rigidity. and adequate setting force and low rate of opening of relief valves in the long-wall face could improve the roof condition.

in the future with the increase of the mining depth the surface land will be mostly in the sub-critical conditions. Under such conditions, it is inevitable that the value of movement angle obtained by surface observations for calculating safety pillars is too small, and of no importance. Based on probability integration method and the data obtained from rock movement observations, the paper has made a mathematic deduction, and a formula for claculating the movement angle values at any conditions is given....

in the future with the increase of the mining depth the surface land will be mostly in the sub-critical conditions. Under such conditions, it is inevitable that the value of movement angle obtained by surface observations for calculating safety pillars is too small, and of no importance. Based on probability integration method and the data obtained from rock movement observations, the paper has made a mathematic deduction, and a formula for claculating the movement angle values at any conditions is given. And it is changed into an expression for calculating the movement angle under critical condition, which is of practical meaning.For the ease of calculation, corresponding graphs are plotted which are fit to the measured data.