Study On The Progressive Weakening Failure Law And Control Technology Of Small Coal Pillars

Fully improving the utilization rate of non-renewable resources plays an important role in the resource recycling economy.Taking Shilawusu coal mine in the inner mining area of Mongolia as the engineering application point,the law of progressive failure of small coal pillar structures is generalized by means of corresponding theoretical and technical methods and methods.Finally,to achieve space of roadway maintenance,put forward the concept of "double-layer strengthening" control technology,and applied to sit industrial tests.By means of a set of monitoring methods,the safety and stability evaluation of "double-layer reinforced" control anchor protection system is realized.The main conclusions reached are as follows:(1)The basic mechanical model of the coal pillar structure was established,and through torque conversion and stress decomposition,the internal displacement trend change model of the coal pillar structure was constructed.Basic spatial relationship.Internal displacement trend change model.Based on this,through the mechanical equilibrium relationship,it is analyzed that in the plane perpendicular to the coal pillar axis inside the coal pillar,there is a curve composed of opposite displacement control points.The structures on both sides of this curve have bit displacements in opposite directions,so The concept of "stability critical line" of coal pillar structure is defined.(2)A physical simulation experiment was designed and implemented against the background of progressive damage of small coal pillars,and by analyzing the physical and mechanical parameters of simulated rock strata,demonstrating the feasibility and correctness of physical experiment operation.The experimental scheme was designed to compare the characteristics of coal pillar cracking,roadway roof cracking,coal pillar failure morphology,roadway roof morphology,and control performance of the anchoring system under the two experimental conditions.Stable "high pre-tightening and strong anchoring" support system.From the macroscopic point of view,the paper generalizes the progressive damage and destruction process of coal pillar structure,and summarizes the macroscopic characteristics of the progressive damage of coal pillar structure.(3)A numerical model for driving roadways with small coal pillars is established,and the law of progressive damage and damage of small coal pillar structures during tunneling is summarized.The distribution rule of the peak value of vertical stress in the space area of the tunnel during the tunneling along the goaf is analyzed.The analysis of the horizontal displacement distribution during the tunneling along the goaf verified the existence of the "stability line of instability" of the coal pillar structure;by fitting the vertical displacement distribution data of the coal pillar structure,it was found that the coal pillar structure was most near the roof Dangerous areas that are prone to compressive shearing and compressive shear damage.Based on the analysis of the changes in the stress transfer of the coal pillar and the control points of the spatial displacement of the coal pillar structure,the internal damage process of the coal pillar structure was summarized from the internal perspective of the coal pillar structure,providing data basis for its space maintenance.(5)Based on the law of progressive destruction of small coal pillars along the roadway by leaving small coal pillars,a “double-layer reinforced” anchoring control technology for the 01 roadway along the roadway at Shilawusu Coal Mine 221 was proposed to cause shallow damage to the roof Surrounding rocks work in coordination with deep stable surrounding rocks,increasing the thickness of the roof stable structure,enhancing the basic stable structure of the roadway,weakening the trend of damage and expansion in the shallow part of the roadway,and effectively achieving the stability control of the roadway roof.(6)Carry out corresponding on-site effect monitoring analysis for engineering tests,and evaluate the space maintenance status of the roadway from multiple angles by means of Roadway Surface Displacement Monitoring,Anchor Body Support Resistance Monitoring,Surrounding Rock Crack Development Monitoring,and Roadway Surface Maintenance Effect Monitoring.The overall performance of the "double-layer reinforced" control anchoring system was evaluated in an index,and it was verified that the application of the "double-layer reinforced" control technology effectively realized the efficient control of the roadway with small coal pillars.