Study On The Support Mechanism Of The New Type Mechanical Reusable End-Anchored Bolt And Its Application

Bolt support has been the main support form of the mine roadway in the under- ground engineering because of its obvious technical and economical superiority. The bolt types are various in coal mine roadway support. Different kinds of bolts have different anchorage performances and different applicable conditions. Resin bolts are dominant in the coal mine roadway support bolts in China. The new type mechanical reusable end-anchored bolt developed recent years has some merits, such as good anchorage performance, the reuse of bolt and quick fixing . However, there is lack of all-round understanding about the support mechanisms of the new type mechanical reusable end-anchored bolt. In this paper, A synthetically study means combined with theoretical analysis, experimental test, numerical simulation and industrial field test is applied to study systematically the mechanical mechanism of the support of the new type mechanical reusable end-anchored bolt. And the study results with innovative significance are shown in the following:(1) Based on the detail study on the structure characteristics of the new type mechanical reusable end-anchored bolt, the stress characteristics of bolt are analyzed systematically, the mechanical performance is comprehensively tested, and the estimating formula of the anchorage force are obtained. On the base of the comparison of the anchorage performance to resin bolts, the applicable conditions of the new type bolt are introduced.(2) Aimed at the stress characteristic of bolt support, the simplified mechanical model is established to analyze the stress and deformation of the anchored surrounding rock. The analytical solution of stress field of the anchored surrounding rock is gained firstly by means of the Boussinesq solution and Mindlin solution in classical elastic theory. The distribution law of the axial, radial and annular stress of the anchored surrounding rock is presented and the difference of stress distribution characteristic between the mechanical reusable end-anchored bolt and resin bolts with different anchored length are compared, which revealed the mechanical mechanism that the anchorage performance of the end-anchored bolt is superior to the resin bolt.(3) Numerical simulation is adopted to study systematically the distribution characteristic of the axial stress along bolt, the radial stress and equivalent stress vertical to bolt in anchored surrounding rock. With the help of strength theory, the influencing law of bolt support with different anchored length on the strength of surrounding rock. The study results indicated that: the strengthening effect of the mechanical reusable end-anchored bolt on the anchored surrounding rock is relatively high, and the strengthening acting range is relatively large.(4) The action effect of bolt support on the stability of roadway surrounding rock is study systematically to present the changing law of the stress, deformation and the plastic range with the anchored length and time. It can be found that: with the decreasing of the anchored length, the acting effect of the roadway surrounding rock similar to a pressure arch enhanced obviously; the roof-to-floor convergence and the side-to-side convergence of roadway decrease obviously; the capability of controlling rheological deformation of roadway strengthened.(5) According to the industrial field test, the support effect of the new type mechanical reusable end-anchored bolt are monitored systematically to verify the stability of surrounding rock supported by this new type bolt and the recoverability of bolt-rod. The monitoring results indicated that the new type mechanical reusable end-anchored bolt has a superior support performance compared to the same standard resin bolt.The study results can provide an important reference for the popularization and application of the new type mechanical reusable end-anchored bolt.