Filling mining method to control ground pressure examples

    First, Zhaoyuan Gold Mountain mine the ore vein 5

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.

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. .

    Second, Jinchuan Nickel Mine Second Mining Area

After the Jinchuan Nickel Mine No. 2 Mine was put into operation in 1982, the design used a down-layer layered cement filling method. In order to obtain the experience of mining technology, technical and economic indicators and the basis of rock mechanics, the downward cementation filling method was tested between the 14-16 exploration lines in the west.

Three layers have been taken (layered height 4m). The extensometer and multi-point displacement meter are used to monitor the deformation of the deep rock mass of the surrounding rock. Long-term measurements by the extensometer show that the surrounding rock is tensile strain, strain value -7683με, average maximum displacement velocity is 0.161mm/d (Fig. 2), the surrounding rock is compressive strain, strain value is 633με, maximum displacement The speed is 0.12 mm/d (Fig. 3).

Fig. 2 Curve of displacement of surrounding rock on the upper plate

(1 to 7 in the figure is the measuring point number)

Fig.3 Curve of displacement of surrounding rock in the lower plate

(1 to 7 in the figure is the measuring point number)

An observation section is arranged in the surrounding rock of the upper and lower plates to monitor the convergence deformation of the rock mass. The 414-day observation results of the six observation sections on the upper plate have a maximum cumulative convergence value of 259.8 mm and a convergence rate of 0.32 mm/d to 1.05 mm/d (Fig. 4).

Fig.4 Convergence curve of section 1~2 of the surrounding rock

The 350-day observation of the six observation sections of the surrounding rock shows that the maximum cumulative convergence value is 460 mm and the convergence rate is 1.4 mm/d (Fig. 5).

Fig.5 Convergence curve of section 1~9 of the surrounding rock

15 level observation points were buried in the 15~17 exploration line at 1300m level to monitor the subsidence of the roof. After 200 days of observation (three layers were taken), the average sinking speed of the top plate was 0.5 mm/d.

In addition, 14 stress meters are buried in the 15~17 exploration line at 1300m level. The measurement results show that the stress in the surrounding rock of the upper and lower plates, with the development of the mining process, is a complex dynamic change of loading and unloading, that is, the stress increases, decreases, and rises again. High, and then the process of repeated changes.

The comprehensive monitoring of the above various means shows that the cemented backfill of the downward stratified cement filling mining method well limits the deformation of the surrounding rock and the roof, and the displacement is small, which can ensure the safety of the mining work and the mining field is good. Steady state.