Research And Application Of The Synergistic Anchorage Mechanism To The Surrounding Rock In Deep Roadways

Stability control of the surrounding rock is one of the key issues in deep coalmining. In recent years, development of anchor material, equipment, and construction techniques has made net- cable anchorage the prevailing control method of roadways. Its design, however, is conducted more by experiences than by the fundamental theory. It leads to two major shortcomings. One is a lack of synergistic effect among the factors within the subsystem of the anchorage system, which fails to maximize the function of the subsystem. The other is a lack of synergistic effect among the subsystems, which brings little synergistic enhancement efficiency to the anchorage system and leads to an insufficient integral effectiveness. As a result, it can neither guarantee the anchoring effect and safety, nor improve drilling efficiency.This thesis studies the deep roadway engineering in the coal mine, and applies synergic principles to stability control of the roadway surrounding rock. It firstly discusses the feasibility, reasonableness and applicability of using synergy in roadway anchorage, and builds a deep roadway stability control system composed of the subsystems of anchorage, surrounding rock and environment. By analyzing the relationship between the displacement of the surrounding rock and the system’s control variable and state parameter, this thesis discusses the reasonableness of using displacement as the system’s order parameter, and thereby builds the system’s mechanical model. The whole anchorage system, macroscopically, achieves more than the simplistic sum of all its subsystems, or the positive synergic efficiency of 1+1 2.On this basis, this thesis makes a multi-level and multi-angle study of the principle, mechanism and efficiency of synergistic anchorage by means of theoretical analysis, model test, numerical simulation and engineering practice. It accomplishes the technical system of synergistic anchorage, and its evaluation index. The whole system performs well in several engineering practices, and achieves integration between the study and its technical application.The thesis draws the following major conclusions.1 The study proves the objective existence of synergistic effect and efficiency in the anchorage system of roadway surrounding rock. What’s more, adjustment and optimization of the anchorage variable can improve both the synergistic effect among the subsystems and the synergistic efficiency of the whole anchorage system, raise significantly the integral strength and stiffness of the anchored rock, and lead to a uniform roadway deformation, a homogeneous surrounding rock stress distribution, and an even load on the anchor bolt(cable). As a result, the anchored rock in the roadway increases greatly its bearing capacity and deformation resistance.2 The study proposes the concept of synergistic incrementi?S and synergistic index iξ, develops their calculation formulae, and adopts them as the evaluation of synergistic effect. When i?S 0, synergistic effect appears and grows as the value rises. When i?S 0, there is zero synergistic effect or even negative effect. When i?S 0, synergistic effect reaches its critical state. Accordingly, when iξ 0, synergistic efficiency appears and grows as the value rises. Wheniξ 0, there is zero synergistic efficiency or even negative efficiency. When iξ 0, synergistic efficiency reaches its critical state.3 Experiments are conducted to study the fixation effect on the anchorage body produced by bolt preload, distribution density and composite members, and find out the working law of synergistic effect, synergistic efficiency, and stress distribution within the anchorage body in case of one and two bolts. With Grey Relational Analysis it is known that when bolt preload and density changes simultaneously, bolt density leaves more obvious influence on the scope of synergistic efficiency within the anchorage body.4 It is known from simulation that synergistic effect exists both within and among such anchorage variables as bolt(cable) preload, density, length, and angle. If they are synergistic, the anchorage system is synergistically more effective and efficient. So the system as a whole functions better than the sum of all its subsystems and single elements. If they are not synergistic, there is no synergistic efficiency of 1 1 2.5 Under the synergistic effect of the anchorage variable, the scope of synergistic efficiency within the anchorage body takes, along the drilling direction of the bolt the shape of an American football which is axially longer and horizontally shorter. As the anchorage variable changes, the scope varies more apparently along the axle. Besides, with the partial length anchorage, the anchoring section and the rock surrounding it form a “big tray” as a result of adhesion. It extrudes and strengthens apparently the rock within a certain range. Thus, the strength and stiffness of the anchored rock rises effectively. This discovery enriches and improves the theory of anchorage reinforcement arch.6 This study establishes the anchorage mechanism to realize the synergistic effect of bolt(cable), including preload synergy, structural synergy, deformation synergy, anchorage timing synergy, strength synergy, stiffness synergy and parameter design synergy. It develops various methods to implement these synergistic mechanisms. On this basis, this study applies the principle and technique of synergistic anchorage to engineering practice, and solves the problems concerning the stability control of the surrounding rock in some deep roadways of high stress and soft rock, and other roadways under complex conditions.As a new concept, synergistic anchorage applies synergistic principles to stability control of the surrounding rock. It offers a new perspective to researchers, provides a scientific guidance and theoretical basis to the study of engineering control mechanism in roadway and similar projects, and develops a reliable, applicable, and effective system of synergistic anchorage technology.