Research On Supporting Effect Of Different Anchor Under Complicated Stress Condition In A Certain Mining

Being an efficient and economical tunnel-support technique,pre-stressed bolt support has been widely used in diferent underground projects.For complexity of interaction between bolt and surrounding rock,it is still in exploring stage and does not form perfectly theory system.The pre-stressed bolting design mainly depends on engineering analogy and the design theory seriously falls behind the engineering practice especially in entry support of metal mine.According to the characteristics of entry surrounding rock in metal mine,the pre-astessed bolting for developing entery in metal mine has been studied because the pre-stressed bolt possesses the characters of early load-bearing and quickly load=bearing and high surrounding rock load-bearing ability.Thepractice indicated that anchorage roof can form a combined beam structure,reduce roof tensile stress area and roof distorion,ameliorate surrounding rock stress distribution an enhance the stability of entry after a suitable pre-stress is applied to the bolt.In order to solve the serious roadway damage and higher repair rate, the tunnel was unstable in 1110 m west sublevel drift of Jinchuan No.3 Mine Area. The numerical analysis on the supporting effect of expanding-shell hollow pre-stressed anchor and fulllength mortar anchor were conducted by FLAC3 D numerical simulation software. By comparing the differences of roadway deformation, surrounding stress field, plastic zone and stress concentration factor in two conditions: one was the different angle between the maximum horizontal principal stress and roadway axis of the two bolt supports, the other was the different maximum horizontal principal stress with the same angle. And compared with the field test data, it was found that the effect for controlling the two sides' displacement of the roadway supported by expanding-shell hollow prestressed anchor is much better than mortar bolt. Besides, the tress in the roadway periphery which supported by expanding-shell hollow pre-stressed anchor is more balanced, this contributes to the long-term stability of the roadway, which can prolong the roadway maintenance cycle and reduce the repair rate.