Filling mining method to control ground pressure examples (1)

The No. 5 vein of Lingshan Gold Mine of Zhaoyuan Gold Mine is a medium-thick and steeply inclined lenticular ore body. From September 1983, the downhole layered cement filling method was tested on the 1903 west stope of the ore body, and it has been promoted and applied in the mining sites such as 1908 and 1909.

In disseminated ore veinlets pyrite phyllic granitic rock fragmentation based on the plate granite, mylonite joints is developed, not stable, easy falling. Sericite footwall of potassium granite, more robust.

The 1903 west mining field is 16m long and 40m high. The width is equal to the thickness of the ore body (average thickness is 14.5m). The ore body inclination angle is 51.5°. The mining approach is arranged along the ore body, with a stratification height of 2.7 to 3.0 m and an access width of 2.5 to 4.0 m. From the upper plate to the lower plate, the two-step recovery is carried out, and one way is taken back through one way, and the cement is filled after the completion of the production. The cemented filling material has a ratio of lime to sand of 1:4 to 1:8 and a weight concentration of 78%. After the two sides of the road are filled with cement, the intermediate approach is taken back. Therefore, the mining operation is carried out in three stages: the first stage, the one-step recovery and the goaf are not filled; the second stage, after the one-step recovery, the goaf The cementation filling is carried out; in the third stage, the two-step rubber-filled inter-body inlet is taken back, and the goaf is not filled.

The finite element calculation and the on-site stress-strain measurement were carried out for each stage of the recovery, and the results are shown in Table 1 and shown in Figure 1.

position	project	Data acquisition method	unit	Mining stage
				The first stage	second stage	The third phase
Route	Maximum principal stress of the top plate (middle of the top plate) Maximum principal stress of the bottom plate (middle of the bottom plate)	Finite element calculation Ibid.	MPa MPa	-2.17 -0.51
Pillar	Maximum principal stress Stress concentration factor	Ibid. Ibid.	MPa	19.9 2.9	17.12 2.49
Charge fill body	Maximum principal stress (vertical top plate)	Ibid. Steel string dynamometer Telemetry strain gauge	MPa MPa MPa		2.62	8.54 2.0 to 2.15 2.4
	Affected by the plate (vertical ore contact surface)	Finite element calculation Steel string dynamometer	MPa MPa			0.51 0.7
on plate Wai rock	Maximum principal stress Maximum shear stress Stress concentration factor	Finite element calculation Ibid. Ibid.	MPa MPa	15.69 5.75 2.3	13.95 4.26 1.96	22.28 7.36 3.27
	Displacement into the stope	Ibid. Multi-point displacement meter	Cm Cm			1.65 2.17

Fig.1 Stress distribution curve of surrounding rock of 1903 west stope

A-recovery first stage; b-recovery second stage; c-recovery third stage

1- top plate σy distribution curve; 2- top plate σx distribution curve; 3- bottom plate σy distribution curve; 4- bottom plate σx distribution curve

It can be seen from Table 1 and Figure 1 that in the first stage of recovery, after a stepping road is recovered, a large vertical compressive stress is applied in the pillar, and horizontal tensile stress occurs in the top of the inlet and the middle of the floor. In the second stage of recovery, that is, after a stepping road for cementation filling and good roofing, the stress concentration of the pillar is moderated, and part of the roof pressure is transferred to the filling body, so the maximum principal stress of the pillar is reduced by 13.7%, and the stress concentration factor is Reduced from 2.9 to 2.49. The third stage filling body is used as the artificial column to support the top and bottom plates. At this time, a large part of the roof pressure has been moved to the surrounding rock of the upper and lower plates, and the pressure above the filling body is small. This fully demonstrates that if the filling is good, the filling body can withstand part of the roof pressure and improve the stress distribution of the roof. Although the surrounding rock has a certain pressure on the filling body, due to the limitation of the filling body, the displacement of the surrounding rock into the stop is small, and the stop is in a stable state under the support of the filling body. .

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