Method for designing supporting parameters of transition support for mixed mining face of filling and fully-mechanized mining

Abstract

Disclosed is a method for designing supporting parameters of a transition support for a mixed mining face of filling and fully-mechanized mining. The method includes: first, determining a total length of a mixed mining working face and a length of a filling section according to requirements of a coal mining production capacity of the mixed mining working face and a filling capacity of the filling section working face; then, establishing a mixed mining numerical model of filling and fully-mechanized mining by using three-dimensional distinct element software, and simulating and calculating a caving height of a roof of a transition section and a stress influence range of the transition section when a filling rate of a mined-out area of the filling section changes; based on a result of numerical simulation and calculation, performing curve fitting according to a correlation coefficient to obtain a functional relationship between the filling rate and the caving height and a functional relationship between the filling rate and the stress influence range of the transition section; and finally designing supporting parameters of a transition support in combination with actual engineering geological parameters. The method can provide a reference for supporting design of a support, and enables a smooth transition between a filling support and a fully-mechanized mining support for a mixed working face, thereby further enriching filling mining theories and expanding the application range of filling mining.

Claims

1. A method for designing supporting parameters of a transition support for a mixed mining face of filling and fully-mechanized mining, comprising: first, determining a total length of a mixed mining working face and a length of a filling section working face according to requirements of a coal mining production capacity of the mixed mining working face and a filling capacity of the filling section working face; then, establishing a mixed mining numerical model of filling and fully-mechanized mining by using three-dimensional distinct element software according to tests of physical and mechanical parameters of coal rock in a working face area, and simulating and calculating a caving height of a roof of a transition section and a stress influence range of the transition section when a filling rate of a mined-out area of a filling section changes; based on a result of numerical simulation and calculation, performing curve fitting according to a correlation coefficient to obtain a functional relationship between the filling rate and the caving height and a functional relationship between the filling rate and the stress influence range of the transition section; and finally, determining parameters of a support of the transition section in combination with actual engineering geological parameters, wherein specific steps of the method are as follows: (1) determining the total length of the mixed mining working face and the length of the filling section working face according to the requirements of the coal mining production capacity of the mixed mining working face and the filling capacity of the filling section working face; (2) establishing the mixed mining numerical model of filling and fully-mechanized mining by using the three-dimensional distinct element software according to the tests of the physical and mechanical parameters of coal rock in the working face area; (3) under the premise that a mining height, the total length of the mixed mining working face, and the length of the filling section working face are determined, simulating the caving height H of the roof of the transition section and the stress influence range of the transition section when the filling rate of the filling section changes; (4) performing curve fitting according to the correlation coefficient to obtain the functional relationship between the filling rate and the caving height and the functional relationship between the filling rate and the stress influence range of the transition section; (5) calculating a caving height H of the transition section of the mixed mining working face according to a designed filling rate in practical engineering, and performing calculation using the following formula to determine supporting strength of the support of the transition section:
F=?H in which: ? is 2.5 MPa/100 m; and (6) calculating a stress influence range S of the transition section of the mixed mining working face according to the designed filling rate in practical engineering, and performing calculation using the following formula to determine a number of supports of the transition section: $N?n=\frac{s^{}}{a}$ in which: N is a minimum positive integer greater than or equal to n, and ? is a width of a single transition support.

2. The method for designing supporting parameters of a transition support for a mixed mining face of filling and fully-mechanized mining according to claim 1, wherein: the filling rate varies in a range of 60% to 80%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a system arrangement of a mixed working face of filling and fully-mechanized mining according to the present invention.

(2) FIG. 2a shows a numerical calculation model of mining of the mixed working face of filling and fully-mechanized mining according to the present invention.

(3) FIG. 2b is a top view of a working face of the numerical calculation model of mining of the mixed working face of filling and fully-mechanized mining according to the present invention.

(4) FIG. 2c is an inclined sectional view of the working face of the numerical calculation model of mining of the mixed working face of filling and fully-mechanized mining according to the present invention.

(5) FIG. 3 is a curve diagram of a filling rate versus a height of a caving zone of a transition section for the mixed working face of filling and fully-mechanized mining according to the present invention.

(6) FIG. 4 is a curve diagram of a filling rate versus a stress influence range of a transition section of the mixed working face of filling and fully-mechanized mining according to the present invention.

(7) In the figures: 1. Filling section; 2. Transition section; 3. Caving section; and 4. Transition section support.

DETAILED DESCRIPTION OF THE INVENTION

(8) A supporting design method for a transition support for a mixed mining working face of filling and fully-mechanized mining in the present invention includes: first, determining a total length L.sub.total of a mixed mining working face and a length L.sub.filling of a filling section working face according to requirements of a coal mining production capacity of the mixed mining working face and a filling capacity of the filling section working face; then, establishing a mixed mining numerical model of filling and fully-mechanized mining by using 3DEC three-dimensional distinct element software according to tests of physical and mechanical parameters of coal rock in a working face area, and simulating and calculating a caving height H of a roof of a transition section and a stress influence range S of the transition section when a filling rate ? of a mined-out area of a filling section changes; based on a result of numerical simulation and calculation, performing curve fitting according to a correlation coefficient R.sup.2 to obtain a functional relationship between the filling rate ? and the caving height H and a functional relationship between the filling rate ? and the stress influence range S of the transition section; and finally, determining parameters of a support of the transition section in combination with actual engineering geological parameters, where specific steps of the method are as follows:

(9) (1) determining the total length L.sub.total of the mixed working face and the length L.sub.filling of the filling section working face according to the requirements of the coal mining production capacity of the mixed mining working face and the filling capacity of the filling section working face;

(10) (2) establishing the mixed mining numerical model of filling and fully-mechanized mining by using the 3DEC three-dimensional distinct element software according to the tests of the physical and mechanical parameters of coal rock in the working face area;

(11) (3) under the premise that a mining height M, the total length L.sub.total of the mixed working face, and a length L.sub.filling of a filling section working face 1 are determined, simulating a caving height H of a roof of a transition section 2 and a stress influence range S of the transition section 2 when the filling rate ? of the filling section changes;

(12) (4) performing curve fitting according to the correlation coefficient R.sup.2 to obtain the functional relationship between the filling rate ? and the caving height H and the functional relationship between the filling rate ? and the stress influence range S of the transition section;

(13) (5) calculating a caving height H of the transition section of the mixed working face according to a designed filling rate ? in the practical engineering, and performing calculation using the following formula to determine supporting strength of the support of the transition section:
F=?H

(14) in which: ? is generally 2.5 MPa/100 m; and

(15) (6) calculating a stress influence range S of the transition section of the mixed working face according to the designed filling rate ? in the practical engineering, and perfoiming calculation using the following formula to determine a number of supports of the transition section:

(16) $N?n=\frac{s^{}}{a}$

(17) in which: N is a minimum positive integer greater than or equal to n, and

(18) ? is a width of a single transition support.

(19) The filling rate ? varies in the range of 60% to 80%.

(20) One embodiment of the present invention is further described below with reference to the accompanying drawings:

(21) Embodiment 1: Using a mine as an example, specific implementation steps are as follows:

(22) (1) According to production capacities of working faces of three levels of main mineable coal seams of the mine, it is designed that a total length of a first mixed mining working face (as shown in FIG. 1) with filling and caving methods is 220 m; in combination with an annual production requirement of underground gangue, the length of the filling section working face is 120 m; and a filling rate of the filling section working face varies in the range of 60% to 80%.

(23) (2) Tests of physical and mechanical properties are performed on coal rock samples in an area of the first mixed mining working face, to obtain physical and mechanical parameters of the coal rock mass. Refer to Table 1.

(24) TABLE-US-00001 TABLE 1 Bulk Shear Tensile Angle of modulus/ modulus/ Cohesion/ strength/ internal Density/ Rock stratum GPa GPa MPa MPa friction/? kg .Math. m.sup.?3 Fine sandstone 1.63 1.2 2.5 1.1 32 2200 Mudstone 0.6 0.32 0.5 0.6 28 1600 Coarse sandstone 2.6 2.32 1.5 1.6 34 2400 Shale 1.87 1.12 2.0 1.0 30 2615 Fine sandstone 1.63 1.2 2.5 1.1 32 2200 Mudstone 0.6 0.32 0.5 0.6 28 1600 Powder sandstone 1.3 0.52 0.7 0.9 30 2250 Fine sandstone 1.63 1.2 2.5 1.1 32 2200 Mudstone 0.6 0.32 0.5 0.6 28 1600 Coal seam 0.8 0.14 0.3 0.5 26 1400 Mudstone 0.6 0.32 0.5 0.6 28 1600 Fine sandstone 1.63 1.2 2.5 1.1 32 2200 Powder sandstone 1.3 0.52 0.7 0.9 30 2250

(25) (3) According to the engineering geological conditions and the physical and mechanical parameters of coal rock mass for the filling and caving mixed working face. 3DEC numerical simulation software is used to establish a numerical calculation model, as shown in FIG. 2. The length?width?height of the model is 300 m?200 m?80 m. Displacements in the horizontal direction are restrained in the periphery, and displacements in the vertical direction are restrained at the bottom. An Mohr-Coulomb model is used for a constitutive relationship.

(26) (4) A caving height of overlying rock of the transition section and a stress influence range of the transition section for the working face are separately simulated and calculated when the length L.sub.filling of the filling section remains unchanged and the filling rate ? changes. A specific simulation scheme is shown in Table 2.

(27) TABLE-US-00002 TABLE 2 Solution Length of the filling section Variant I 120 m ? = 60%, 65%, 70%, 75%, 80%

(28) (5) Based on the simulation result, curve fitting is performed according to a correlation coefficient R.sup.2 to obtain a functional relationship between the filling rate ? and the caving height H and a functional relationship between the filling rate ? and a stress influence range S of the transition section 2, as shown in FIG. 3 and FIG. 4.

(29) (6) An actual on-site filling rate is around 70%. It is calculated from FIG. 3 that a caving height H of the transition section 2 of the mixed working face is about 30.5 m. The supporting strength of a support of the transition section 2 is determined through calculation:
F=?H=0.7625 MPa

(30) in which: ? is 2.5 MPa/100 m.

(31) (7) It is calculated from FIG. 4, according to the designed filling rate ? in the practical engineering, that a stress influence range S of the transition section 2 of the mixed working face is about 6.2 m, and calculation is performed using the following formula to determine the number of supports of the transition section 2:

(32) $N?n=\frac{s^{}}{a}=4.13$

(33) in which: N is a minimum positive integer greater than or equal to n, and

(34) ? is a width of a single transition support, and is taken as 1.5 m.

(35) Finally, taking a certain allowance coefficient into consideration, it is designed that the supporting strength of supports of the transition section is 0.84 MPa, and the number of supports of the transition section is 4.