Determining the Permissible Longwall Face Advance in the Protective Pillar Conditioning the Liquidation of a Mining Shaft

The presented research subject involved the assessment of the possibility of mining operations within the area of shaft protection pillar with simultaneous liquidation of the shaft. In such a situation, the basic condition is to avoid damage to shaft lining, which can hinder or even prevent safe liquidation of the shaft by backfilling. The procedure to follow in order to assess the possibility and scope of mining exploitation within the shaft protection pillar is demonstrated on the example of shaft X. The applied assessment method involving the possibility and scope of mining exploitation within the protective pillar of the shaft was based on the forecast of rock mass deformation at the shaft site, which was the basis to calculate vertical stresses in the shaft lining and then to compare them with permissible values. The carried out calculations allowed us to determine the permissible face advance of longwall No. 5 at which no damage to the lining and its equipment would occur, ensuring the planned safe liquidation of the shaft by backfilling.

The Justice and Security Dialogue Project: Building the Resilience of Non-State Actors to Atrocity Crimes

The doctrine of “responsibility to protect” obliges all states to protect populations from “atrocity crimes”—namely, genocide, war crimes, crimes against humanity, and ethnic cleansing—under three “pillars” of protection. Pillar One requires a state to protect its own population from atrocity crimes. Pillar Two obliges the international community to help states to exercise this responsibility through diplomatic, humanitarian, and other peaceful means. When both of these approaches fail, states must pursue a “Pillar Three” strategy: the UN Security Council must “take collective action, in a timely and decisive manner.”

Study on the Magnitude of the Roadway-Protection Pillar in the Isolated Face

In the actual production process, Zhengli Coal Mine has a problem to make sure that the width of chain pillars. This paper from the view of field application with theoretical calculation and numerical simulation method to calculate and verify the stability and security of the chain pillars, It achieved good effect and finally determined the width of chain pillars.

Stability Analysis of Central Haulage in Baluba Copper Mine

Site observations were conducted to investigate the reasons for the poor current rock-mass conditions being experienced in essential crosscuts, to provide recommendations for remedial support measures. Conceptual analyses of mining induced stresses within abutment pillars were undertaken using elastic analytical and mathematical modelling. The results showed that damage to the crosscuts is due to high mining-induced stresses, with the major stress probably acting vertically, the protection pillar for the 480 Level crosscut should be at least 100 m wide. The research demonstrated that only 2.4 m grouted rock-bolts and timber sets is not enough in these conditions, so the 480 Level and 580 Level central haulage should be re-supported with a combination of 4.0 m pre-tensioned cable-bolts, a 75 mm layer of steel mesh (or fibre) reinforced shotcrete, and even steel arch sets with lots of log.

Distribution of Underground Pressure Law and Fracture Zone Prediction Research of Overburden in Steep and Multiple Coal Seams Mining

Use Taiping coal mines second horizontal (+1100m~+900 m level ) 1#, 3# and 5# coal seam in Panzhihua Baoding as the research object, apply the problem solving nonlinear large deformation finite difference method (FLAC), to research the steep multi-seam mining of pressure distribution and characteristics of fracture zone. The results show that: (1)During the course of three coal mining extraction, the stress of goaf surrounding rocks will be changed. (2)When the nearby coal is mining, the coal pillar come into being stress concentration near the area. when the mining work continues, the goaf will have an effect on the protection pillar, which is similar to the "liberate". the effect of coal pillar and stress concentration nearby will be eased; (3)After the coal mining, plastic failure has occurred over the protection pillar, forming a water guide channel. Research results can be as a reference for similar steep seam mining.

Determination of Strata Displacement Angles under Subcritical Mining

With the surface movement observation data derived from subcritical mining, Matlab curve fitting is applied to calculate predicting parameters of the probability integral method. Other conditions kept unchangeable, the size of the working face is extended to achieve full exploitation degree. The displacement and horizontal strain values are calculated by use of the probability integral method, and the subsidence, slope, curvature, horizontal strain curves are generated, thus, the displacement angles of strata under the condition of critical mining are consequently inversed. It is of theoretical significance and of practical value for delimiting the damaged scope and designing the protection pillar size reasonably.

Research on Mine Pressure Behave Law in Mining of Face under the Coal Pillar

When mining close-distance seams with downlink mining, in order to benefit roof maintenance and management, the decoration of lower seam roadways should try to avoid the area affected by pillar concentrated stress , using inside cross decorationg; In order to improve the recovery rate of resources, the size of protection pillar can’t be too big, when mining under pillar of upper layer and mining in pillar of upper layer with crossing. The whole lower face or some phase located under the influence of upper coal concentration stress, give roadways and working face roof maintenance a lot of difficulties. Then it appeared the conflict between security and economy, to solve this problem, we must return to the correct understanding of mine pressure behave law. In the paper, through the investigation of the typical dozen example in mining of face the coal pillar in China, to get its regular pattern of mine pressure behave, in similar conditions mining, there will be important reference and guidance.