1、英文原文Stability analysis for main roof of roadway driving along next goafBAI Jian-biao(School of Energy Science and Engineering, China University of Mining & Technology, Xuzhou, China)Abstract: Focusing on the stability of surrounding rock around the roadway driving along next goaf with a narrow coal
2、pillar, a mechanics model of the triangle block structure of main roof above the roadway is established, and the sliding stability coefficient K1 and the rotation stability coefficient K2 are proposed to describe the stability of the triangle block structure quantitatively. The structure can keep a
3、self stability before and after the roadway excavation, at the stage of mining-induced effect, the stability of the structure is lowered, and the structure may become instability with decreasing the coal strength, increasing the mining height of working face and the mining depth.Keywords: roadway dr
4、iving along next goaf; triangle block structure; stability analysisWith face advancing, the main roof results in periodic breaking, and the rock blocks after breaking are along the face strike direction formed into a voussoir beam structure. The breaking form in the face end is an arctriangle block
5、1 as shown in Fig. 1.In general, the roadway driving along next goaf can not affect the stability of arc triangle block structure in the upper working face, and affected by advance abutment pressure of the face mining, the stability of arc triangle block structure and the moving state must take plac
6、e in greater change2, 3, and the field practice also indicated that the deformation of roadway driving along next goaf is smaller at the stage of the excavating influence and at the stable stage after excavation, but after the mining induced effect of the working face, the surrounding rock activity
7、of roadway is violent and itsdeformation is also greater4.Fig. 1 The triangle block structure of roadway driving along next goaf1 Mechanics model of triangle block structure of main roof 21. 1 Establishment of mechanics model of triangle block structureAccording to Fig. 1, the arc triangle block str
8、ucture is simplified as follows:(1)The triangle block B, rock mass A on the solid coal side and the block body on the side of goaf C form an articulated structure, because the periodic weighting advance of a working face is basically equal, i. e. the breaking characteristics of main roof is basicall
9、y similar, the arc triangle block is simplified into the isosceles triangle block, called triangle block for short, and its side length in the rib is equal to the periodic weighting advance of the working face, other two sides are equal.(2)The soft and weak strata above the main roof are considered
10、as loading exerting on the main roof, and before suffering the mining induced effect of working face, the weak strata above the triangle block B and the upper hard strata result in delamination and the force transmission is also lost.(3)When driving the roadway along next goaf with a narrow coal pil
11、lar, at the stage of mining induced effect of working face and under the superposed action of the side abutment pressure and the advance abutment pressure, the coals below the rock block A and the immediate roof as well as the waste rock below the rock block C should lead to compressive subsidence,
12、but the rock block B results in rotation subsidence and its stability and position state should be changed.According to above simplification, a mechanics model of triangle block structure of roadway driving along next goof is established as shown in Fig. 2. Fig. 2 Section of mechanics model of trian
13、gle block structure (I-I section)1. 2 Study on the parameters of the triangle block BThere are mainly three parameters of the triangle block structure, i. e. the breaking length L1 of main roof along the face advancing direction, the breaking span L2 along the side direction and the breaking positio
14、n X0 of triangle block in the coal seam, as shown in Fig. 1 .And the basic dimension of the triangle block B should be determined by the periodic weighting advance and the breaking pattern of the main roof during the periodic weighting. (1)Determination of L1 .From Fig. 1, it can be seen that the br
15、eaking length L1, of triangle block along the face advancing direction is the periodic weighting advance of the main roof, its value can be obtained by theoretical calculation and field observation, and L1 can be calculated by 5 (1-1)Where, h is the thickness of main roof, m; Rt is the tensile stren
16、gth of main roof, MPa; q is the loading suffered by unit area of main roof, MN/m2. (2)Determination of L2. According to the analysis method of the plate yielding line, L2 is related to the face length S and L1, and L2 can be calculated by6 (1-2)On the basis of the calculating analysis6 , if S/L16, the crossrange span L2 of triangle block conforms to the periodic weighting adv
