| The roof fall accidents of full-mechanized excavation head-on roadway take place frequently and the tunneling efficiency is low. The key technical problems to be solved immediately are supporting the head-on roof timely and effectively by the temporary supporting equipment employed, the optimization of the excavation process, and the parallel working of excavating, supporting and anchoring simultaneously. Based on lots of theories and papers consulted, and combined with the National Natural Science Fund Project" Research on stepping-type supporting equipment in advance and tunneling head-on roof dynamic coupling mechanism (number:51304107)"and the national invention patent of independent intellectual property rights "Hydraulic stepping-type supporting equipment in advance", the full-mechanized excavation tunnel supporting system in advance and its control technique are studied by means of local investigation, theoretical analysis, numerical simulation and experimental research. The main research results are as the followings:(1) The formation of process and the stress variation regulations of the roof for full-mechanized head-on roadway and the process demands of excavation are analyzed, the temporarily supporting the head-on roof by hydraulic stepping-type supporting equipment in advance is put forward. Based on the rock mechanics of anisotropythin plate and the thick plate, the statics models and the dynamics models for these two models are built respectively. The displacement and stress strain variation regulations of the roof are obtained by the numerical simulation. The head-on roof supporting criterion is proposed by studying on the roof fracture characteristic and comminuting mechanism. According to the requirements for the roof temporary supporting, the demands of the setting force, the working resistance for the supporting system in advance are confirmed, and the design requirements of the supporting system in advance are presented.(2) Based on the roof temporary supporting requirements of full-mechanized excavation tunnel, a hydraulicalternating stepping-type supporting system in advance is developed. According to the interaction between the equipment and the roof, the statics and dynamics model of a singleset of support and double support for the supporting equipment in advance is established respectively. Then the statics and dynamics characteristics of the supporting equipment in advance itself are concluded.(3) According to the difference of contact forms between the top beams of the supporting equipment in advance and the head-on roof, and by means of the principle of deformation compatibility, the statics models of the supporting equipment in advanced-roof system are respectively established under the conditions of top beam multipoint distribution supporting and full contact supporting. By analyzing the working principle and structure characteristics of the supporting equipment in advance, the coupling dynamics model of the supporting equipment in advanced-roof system under the conditions of top beam multipoint distribution contact and full contact is established, and the interaction coupling dynamic characteristics between the supporting equipment in advance and the roof in the process of equipment stepping and moving alternately is researched.(4) According to the mechanics numerical simulation of the full-mechanized excavation head-on roof, the regulations of the static and the dynamic displacement characteristics for the roof are obtained. The numerical simulation research on the statics and the dynamics of the equipment itself is performed, and the variation regulations of the displacement characteristics, the dynamic characteristics and the modalch aracteristics when the supporting equipment in advance is working are received. By the numerical simulation of the statics and the dynamics for the supporting equipment in advance-roof system, the displacement characteristics, the contact force distribution characteristics, and the dynamic coupling characteristics of the interaction between the supporting equipment and the roof are respectively computed corresponding to the multipoint distribution contact, the full contact of top beam, a single set of supporting and the double supporting.(5) Based on working principle and force characteristics of the interactionbetween the supporting equipment in advance and the roof, under the constraint conditions of reducing disturbance to the roof, the influencesof transitionstate supporting’s variation on roof when a singleset of supporting changes to double supporting or a doubleset of supporting changes to a single supporting are researched. The optimal load and unload characteristic curves of support pressure are obtained by the numerical simulation calculation. By means of the electro-hydraulic servo controlprinciple, the load and unload characteristics are achieved by controlling the working pressure of the hydraulic stepping-type supporting system in advance to realize the loading and the unloading.(6) The loading experimental equipment and the hydraulic stepping-type supporting system are developed to simulate the tunnel roof characteristics. By the mechanics simulation of the full-mechanized excavation tunnel head-on roof, the experiment is performed to validate the statics and the dynamics under the interaction support equipment and roof. The comparison is carried out between the experiment data and the theoretical result, and the theoretical research achievements are validated and improved. |
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