Reinforcement And Permeation Mechanism Of Grouting And Application Analysis In Jointed Coal-rock Masses

Grouting, as a high practicable and widely applied technology, especially in reinforcement project of rock and soil masses, has become an effective way to improve structure, performance and bearing capacity of rock and soil masses. Due to grouting engineering belonging to hidden project and the fracture distribution of coal-rock masses in-situ is complex, the development of it is un-mature so far, and it's short of a method to predict the pentration scope of grouts. Research of grouting material plays a significant role in the technology of grouting, whose physical peformance and mechanical peformance of the calulus body are most important factors that influence the grouts penetration and consolidating effect. Based on the analysis and summary of present researches and existing preblems of grouting theories, grouting materials and grouting methods, deep researches were carried out and the main work is as follow:⑴Considering pentration process of grouts in coal-rock masses under grouting pressure, the wall of bore-hole breaks, the crack conceiving and expanding process were analized by using the theory of mechanics of elasticity and fracture, which provides the theory basis for grouting initiation point determiantion of grouting flowing in jointed coal-rock masses.⑵Based on systematical research of orientation, harshness, aperture, trace and configuration of structure surface, the Bingham flowing model in sigle fracture was set up with considering the plug flow region and inlet grouting low volume rate through seizing main factors that affects grouting penetration.⑶Through real analysis of grouting expending process of fracture tip and considerations of stress field distribution rule around fracture tip under the action of ground stress and grouting pressure, the stress intensity factor of fracture tip at the state of ompressive-shear and tensile-shear conditions were induced, and fracture expending criterion, orientation and length were given, which establish the basis for analysis of pressure grouts flowing in intermittent fractured network.⑷Take splitting analysis of surrounding rock of bore-hole wall, grouts flowing law in single facture and grouting splitting impact on fracture tip as basis, FORTRAN language was used to produce the grouts flowing simulation program GROUT.FOR which can simulate the grouts flowing scope in intermittent fractured network. It provides science basis for later digitization design of grouting projects of coal-rock masses.⑸As for grouting projects of fractured coal-rock masses, the grouting materials performance including grainness size, flowability and stability of grouts and so on influence intensely the grouts pemeation pattern and results in coal-rock masses. When the performance of grouting materials is different, the seepage mechanism is also not completely identical and the permeation results is various too. According to the deficiency of grouts nowadays, especially existence of H2S affects the safety in production seriously and the activity of coal influences directly grouts flowing stability in intermittent fracturd network of grouting project in Ningtiaota Coal Mine, the compound grouts was made up through laboratory test in order to improve the grouts stability, to decrease the concentration of H2S, reduce the grouting cost and guatantee the penetration effect.⑹Applying researches all above to the grouting reinforcement project in Ningtiaota Coal Mine of Shaanxi Coal Corp., the grouts flowing enmulation simulation was realized and use of optimize compound grouts ensured the fine grouting effect and decrease the concentration of H2S. The tunnel stability estimation demonstrates that the reinforcemnet of surrounding rock is well and achieves remarkable economic and social benefits.