It is difficult to maintain the roadway around a fault because of the fractured surroundings, complex stress environment, and large and intense deformation in the mining process. Based on a tailgate of panel $2205 in Tunliu colliery, in Shanxi province, China, we investigated the evolution of stress and displace- ment of rocks surrounding the roadway during the drivage and mining period using theoretical analysis, numerical simulation and field trial methods. We analyzed the deformation and failure mechanisms of the tailgate near a fault. The deformation of surrounding rock caused by unloading in the drivage period is large and asymmetric, the roadway convergence increases with activation of the fault and secondary fracture develops in the mining period. Therefore, we proposed a specific control technique of the road- way along a fault as follows： （1） High-strength yielding bolt not only supports the shallow rock to load- bearing structures, but also releases primary deformation energy by use of a pressure release device in order to achieve high resistance to the pressure retained： （2） Grouting of near-fault ribside after initial stabilization of the rock deformation is used to reinforce the broken rock, and to improve the integral load-bearing capacity ol~ the roadway. The research results were successfully applied to a field trial.
A reasonable unsupported roof distance(URD) when advancing underground coal mine roadways can contribute greatly to safe and rapid roadway development.A mechanical model of the roof,using the relationship between the roof stress distribution and URD,obtained by the difference method,and roof stability according to the in-situ roof stress and rock mass strength was developed.We subsequently designed a proper range of URD,developed a testing method of URD with the function of mining protection,evaluated roof stability through analyzing the test data and then determined a reasonable URD.Considering the factors of the geological conditions,the immediate roof stability and the efficiency of the labor arrangement system,the URD of the advancing roadway of 9802 working face in Zhangshuanglou coal mine was determined to be 6 m using the proposed method.The results show that,when a 2 m length of roadway was reinforced by temporary support and high pre-stressed bolt support after the roadway advancement of 6 m per cycle,the speed and the security of the roadway development can be achieved and the advance rate can reach more than 400 m per month.
Chen YongBai JianbiaoYan ShuaiHao ShengpengDao Viet Doan
In order to avoid the deep-well oil shale roadway being deformed, damaged, or difficult to maintain after excavating and supporting in Haishiwan coal mine, this paper has analyzed the characteristics of the deformed roadway and revealed its failure mechanism by taking comprehensively the methods of field geological investigation, displacement monitoring of surrounding rock, rock properties and hydration properties experiments and field application tests. Based on this work, the high-resistance controlled yielding supporting principle is proposed, which is： to ＂resist＂ by high pre-tightening force and high stiff- ness in the early stage, to ＂yield＂ by making use of the controlled deformation of a yielding tube in the middle stage, and to ＂fix＂ by applying total-section Gunite in the later stage. A high-resistance controlled yielding supporting technique of ＂high pre-tightening force yielding anchor bolt ＋ small-bore pre-tight- ening force anchor cable ＋ rebar ladder beam ＋ rhombic metal mesh ＋ lagging gunite＂ has been estab- lished, and industrial on site testing implemented. The practical results show that the high-resistance controlled yielding supporting technique can effectively control the large deformation and long-time rheology of deep-well oil shale roadways and can provide beneficial references for the maintenance of other con-generic roadways.Deep-well Oil shale
Yu YangBai JianbiaoWang XiangyuWang JundeXue ShizhiXu Ke
The soft rock's heterogeneity and nonlinear mechanical behavior cause extremely difficult maintenance on the soft rock roadway. Aiming at the asymmetric deformation and destruction phenomenon appearing after excavating and supporting the 7101 air return way in Meihe mine, this paper comprehensively adopted a variety of methods to analyze the roadway surrounding rock deformation rule, obtaining the roadway surrounding rock stress and plastic zone distribution rule under no supporting condition and the roadway surrounding rock deformation features under original symmetric supporting condition.Furthermore, this paper revealed the catastrophe mechanism, and proposed the concept of ‘‘weak structure'' and the disaster countermeasure of ‘‘overall stabilizing the roadway and strengthening the support of weak structure''. The industrial test shows that the disaster control technology can realize the coordination deformation of the supporting structure and roadway surrounding rock, thus significantly controlling the deformation of roadway surrounding rock.
