Influence of depth-thickness ratio of mining on the stability of a bedding slope with its sliding surface in concave deformation

In order to study the influence of depth-thickness ratio on bedding slope stability, whose sliding surface is flexural concave in shape under mining conditions, this paper aims to study the characteristics ofdeformarion and damage of bedding sliding with depth-thickness ratios of 200：1,150：1,120：1,100：1 and 50：1 by adopting numerical simulation analysis software combined with laboratory-made ＂under the influence of mining variable sliding surface slope similar simulation test bed＂, and to propose identification methods for slope stability under the infuence of mining. The results show that mining activities under the slope reduce slope stability. With a decrease in the mining depth ratio, the influence of mining on the slope increases gradually, and the damage to the slope gradually expands, the stability of the slope grad- ually reduces, fracture occurs on the slope toe and the central fissure gradually develops to the surface, and reaches slide threshold when the depth-thickness ratio is 50：1.

Reliability analysis on bolt support structure of coal roadway under the influence of mining

Based on the features of the serious deformation of coal roadway,many random variables of the mechanics of the surrounding rocks and the influence of mining, the reliability analysis model of the support structure of coal roadway under the influence of mining is established,and the calculating formulas of reliability of the support structure is obtained with the engineering structure reliability theory. And the reliability is calculated based on the method of Monte Carlo to the coal roadway which is exampled on the influence of mining or not. The relationship between support parameters and reliability, the mining influence coefficients and reliability is established, which provides theory foundations for the design of the coal roadway bolt support.

Theory and test research on permeability of coal and rock body influenced by mining

Stress distribution rules and deformation and failure properties of coal and rockbodies influenced by mining were analyzed.Experimental research on permeability of coaland rock samples under different loading conditions was finished in the laboratory.In-situmeasurement of coal permeability influenced by actual mining was done as well.Theoryanalysis show that permeability varied with damage development of coal and rock understress,and the influence of fissure on permeability was greatest.Laboratory results showthat under different loading conditions permeability was different and it varied with stress,which indicated that permeability was directly related to the loading process.In-situ testsshowed that permeability is related to abutment stress to some degree.The above resultsmay be referenced to gas prevention and drainage.

De-stressed mining of multi-seams:Surrounding rock control during the mining of a roadway in the overlying protected seam

Surrounding rock control in the overlying protective coal seam is a challenging topic for de-stressed mining of multi-seamed coal.Current research findings on roadway control were used in the design of a physical model of a complex textured roof having a varying thickness.The model was used to study roadway instability and collapse caused by dynamic pressure.The results show that when the thickness of the roof exceeds the bolted depth the roadway security is least and the roof has the greatest possibility for collapse.Numerical simulations were also carried out to study stress redistribution before and after roadway excavation during underlying protective seam mining.The evolution of roadway displacement and fracture,as affected by support methods,has been well studied.A series of support principles and technologies for mining affected roadways has been proposed after demonstration of successful practical application in the Huainan Mines.These principles and technologies are of extended value to deep coal mining support in China.

Mechanics criterion and factors affecting overburden stability in solid dense filling mining

The effect of controlling strata movement in solid filling mining depends on the filling rate of the goal. However, the mechanical property of the overburden in the backfill stope and the designed size of the backfill mining workface should also be considered. In this study, we established a main roof strata model with loads in accordance with the theory of key strata to investigate the stability of the overburden in solid dense filling mining. We analyzed the stress distribution law of the main roof strata based on elastic thin plate theory. The results show that the position of the long side midpoint of the main roof strata failed more easily because of tensile yield, indicating that this position is the area where failure is likely to occur more easily. We also deduced the stability mechanics criterion of the main roof strata based on tensile yield criterion. The factors affecting the stability of the overburden in solid dense filling mining were also analyzed, including the thickness and elasticity modulus of the main roof strata, overlying strata loads, advanced distance and length of workface, and elastic foundation coefficient of backfill body. The research achievements can provide an important theoretical basis for determining the designed size of the solid dense filling mining workface.

Failure characteristics of surface vertical wells for relieved coal gas and their influencing factors in Huainan mining area

Based on data from through-hole and logging,we studied the failure characteristics of surface drainage wells for relieved coal gas in Huainan mining area and its influencing factors.The results show that the damaged positions of drainage wells are mainly located at the thick clay layer in the low alluvium and the lithological interface in the upper section of bedrock in west mining area.The failure depth of casing is 244-670 m and concentrates at about 270-460 m deep.These damaged positions are mainly located in the bending zone according to three zones of rock layers in the vertical section above the roof divided. Generally,the casing begins to deform or damage before the face line about 30-150 m.Special formation structure and rock mass properties are the direct causes of the casing failure,high mining height and fast advancing speed are fundamental reasons for rock mass damage.However,the borehole configuration and spacing to the casing failure are not very clear.

Finding Nuggets in Patent Portfolios: Core Patent Mining and Its Applications

Patents are critically important for a company to protect its core business concepts and proprietary technologies. Effective patent mining in massive patent databases not only provides business enterprises with valuable insights to develop strategies for research and development, intellectual property management, and product marketing, but also helps patent offices to improve efficiency and optimize their patent examination processes. This paper describes the patent mining problem of automatically discovering core patents （i.e., novel and influential patents in a domain）. In addition, the value of core patent mining is illustrated by revealing the potential competitive relationships among companies in their core patents. The work addresses the unique patent vocabulary usage which is not considered in traditional word-based statistical methods with a topic-based temporal mining approach that quantifies a patent＇s novelty and influence through topic activeness variations. Tests of this method on real-world patent portfolios show the effectiveness of this approach over state-of-the-art methods.