A stress coordination method for a stope in strip filling mining of a mine

Abstract

The present invention discloses a stress coordination method for a stope in strip filling mining in a mine, which includes the following steps: S1. Strip division: According to the stability of the roof, the mining panel to be mined is divided into an even number of strips, and each strip is perpendicular to the strike of the ore body; S2. Stoping: The upward stoping is carried out in sequence from the first strip to the Nth strip; N is an integer ≥ 2; S3. Waste rock grouting filling: After the stoping of the Kth strip, the waste rock is grouted upward along the strip to fill the goaf formed after the mining of the (K - 1)th strip; K is an even number ≥ 2; S4. Waste rock bottom paving: After the stoping of the (K + 1)th strip, in the goaf formed after the mining of the Kth strip, a layer of waste rock bottom paving body is poured with waste rock concrete; S5. Tailings filling: After the waste rock bottom paving body of the Kth strip starts to set, the tailings are cemented and filled upward along the strip to fill the goaf formed after the mining of the Kth strip.

Description

Technical Field

[0001] The present invention relates to the technical field of mine backfill mining, and more specifically, to a stress coordination method for a stope in strip backfill mining of a mine. Background Art

[0002] Backfill mining is the key to green mining in underground mines. It can not only effectively control the ground pressure in the stope to prevent surface subsidence, improve the recovery rate, but also reduce the discharge of surface waste. During the two-step strip backfill mining process in gently inclined ore deposits, the ore body is generally divided into ore room strips and ore pillar strips, mined in two steps, with one strip mined at a time and the other left unmined. After the ore room strips are mined in the first step, the ore room strips are mostly filled with waste rock cemented backfill bodies with higher strength. After all the ore room strips are mined and filled, the ore pillar strips are mined in the second step. After the ore pillar strips are mined in the second step, tailings backfill bodies with lower strength are filled. The formation of a composite structure by alternating filling of different strong and weak media jointly bears the roof load.

[0003] Due to the differences in the deformation characteristics of different strong and weak media in the composite structure, under the constraint of the rigid roof in the stope, the vertical deformations of different strong and weak media are not much different, but the load differences in each area within the composite structure are obvious, showing a highly uneven stress distribution characteristic. The relatively flexible tailings backfill body is subjected to a smaller load, and the relatively rigid waste rock backfill body is subjected to a larger load. The composite structure shows extremely uneven loading, and most of the support load is concentrated on the waste rock backfill body. The loads borne by each supporting medium in the composite structure do not match their ultimate load-bearing capacities. Moreover, after all the ore rooms are mined and filled, the ore pillars are mined and filled in the second step. The waste rock backfill body independently bears the roof load for a long time, resulting in damage and continuous development, and even support failure, reducing the support force of the composite structure and even causing the overall instability of the stope; while the tailings backfill body cannot fully exert its bearing capacity. This highly uneven stress distribution state is not conducive to the stability of the backfill body and the stope roof, and the ground pressure management efficiency is low.

[0004] The most direct ways to improve the stability of the composite structure are: (1) increasing the strength grade of the waste rock backfill body to improve the safety factor; (2) increasing the deformation modulus of the flexible backfill body or reducing the deformation modulus of the rigid backfill body to reduce the difference in deformation characteristics between materials, transfer part of the load to the flexible backfill body, and achieve stress coordination. However, there are the following problems:

[0005] If the strength grade of the tailings waste rock backfill body is directly increased to maintain the stability of the stope, part of the loads on the tailings backfill body and the ore rock will be transferred to the waste rock backfill body, further increasing the load on the waste rock backfill body. The relative stability of the stope has not been improved by a corresponding margin, and the filling cost has also increased significantly.

[0006] Improving the deformation modulus of the tailings backfill can, to a certain extent, improve the uneven distribution of stress in the composite structure. However, to significantly increase the deformation modulus of the tailings backfill, a large amount of cementitious materials such as cement need to be added, and the filling cost will increase sharply. If the deformation modulus of the waste rock backfill is reduced, its strength will also decrease accordingly, and the safety factor of the waste rock backfill is not significantly improved. Therefore, the method of improving the uneven distribution of stress in the composite structure by directly increasing the deformation modulus of the flexible backfill or reducing the deformation modulus of the rigid backfill is economically unreasonable or ineffective.

[0007] Therefore, how to provide a stress coordination method that neither changes the strength of the waste rock backfill, nor changes the elastic modulus of the waste rock or tailings backfill, and can effectively transfer part of the load to the tailings backfill is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0008] In view of this, the present invention provides a stress coordination method for a stope in strip filling mining of a mine, aiming to solve the above technical problems.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] A stress coordination method for a stope in strip filling mining of a mine, comprising the following steps:

[0011] S1. Strip division: According to the stability of the roof, the mining panel to be mined is divided into an even number of strips, the width of each strip is 5 - 10 m, and each strip is perpendicular to the strike of the ore body;

[0012] S2. Stoping: When mining the first strip, use the cutting raise as the working space and carry out upward stoping along the first strip; after the first strip is mined, continue to mine the second strip; when mining the Nth strip, use the goaf formed by mining the (N - 1)th strip as the working space and carry out upward stoping along the Nth strip; after the Nth strip is mined, continue to mine the (N + 1)th strip; the mining time for each strip is M1 days; N is an integer ≥ 2;

[0013] S3. Waste rock grouting filling: After the Kth strip is mined, carry out upward waste rock grouting filling of the goaf formed after mining the (K - 1)th strip along the strip; the waste rock grouting filling time for each strip is M2 days; K is an even number ≥ 2;

[0014] S4. Waste rock bottom paving: After the first strip is mined, pour a layer of waste rock bottom paving body with waste rock concrete in the goaf formed after mining the last strip in the upper panel; after the (K + 1)th strip is mined, pour a layer of waste rock bottom paving body with waste rock concrete in the goaf formed after mining the Kth strip; the time from the start of pouring the waste rock bottom paving body to the initial setting of the waste rock bottom paving body for each strip is M3 days; M2 ≤ M1, M3 + M4 ≤ M1;

[0015] S5. Tailings filling: After the initial setting of the waste rock bedding body in the Kth strip, the mined-out area formed after mining the Kth strip is filled with upward tailings cemented filling along the strip; the tailings cemented filling time for each strip is M4 days.

[0016] The relationship between the thickness of the waste rock bedding body and the height of the mined-out area is:

[0017] ;

[0018] where, l is the thickness of the waste rock bedding body (m); σ1 is the uniaxial compressive strength of the waste rock strip (MPa); σ2 is the uniaxial compressive strength of the tailings strip (MPa); E1 is the elastic modulus of the waste rock cemented filling body (MPa); E2 is the elastic modulus of the tailings cemented filling body (MPa); h is the height of the stope (m).

[0019] By adopting the above technical solution, a layer of waste rock bedding body is pre-cast with waste rock concrete at the bottom of the tailings cemented filling body. If the tailings cemented filling body and the waste rock bedding body are regarded as a whole, the equivalent elastic modulus of the whole tailings filling strip is increased, which will provide a stronger support effect on the roof, mobilize the bearing capacity of the tailings filling strip itself, and can relieve the pressure of the waste rock filling strip, transfer part of the load to the tailings filling body, coordinate the stress state of the composite structure body, and make the load borne by each phase support medium in the composite structure body match the ultimate load it can bear, reducing the filling cost.

[0020] The greater the thickness of the waste rock bedding body, the better the stress coordination effect. However, when the thickness of the waste rock bedding body is greater than l, the stress coordination effect is no longer obvious. The above technical solution determines l as the optimal thickness of the waste rock bedding body, controlling the stress coordination cost.

[0021] By adopting continuous mining and filling in strips, the tailings filling body can provide support force as early as possible, reducing the bearing of the waste rock filling strip.

[0022] It can be seen from the above technical solution that compared with the prior art, the present invention discloses a stress coordination method that neither changes the strength of the waste rock filling body, nor changes the elastic modulus of the waste rock or tailings filling body, and can effectively transfer part of the load to the tailings filling body, which has the characteristics of high filling body bearing efficiency and low filling cost, and is especially suitable for underground mines with sufficient waste rock. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0024] Figure 1 The accompanying drawing is a schematic diagram of the present invention when a certain panel has not been mined;

[0025] Figure 2 is Figure 1 a schematic cross-sectional view in the A-A direction in;

[0026] Figure 3 is a schematic diagram of the present invention when the mining of a certain panel is completed;

[0027] Figure 4 is Figure 3 a schematic cross-sectional view in the B-B direction in.

[0028] Wherein:

[0029] 1 - unmined rock; 2 - waste rock cemented filling body; 3 - tailings cemented filling body; 4 - waste rock bottom layer; 5 - waste rock filling strip; 6 - tailings filling strip. Specific implementation manner

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0031] Embodiment 1

[0032] The embodiment of the present invention discloses a stress coordination method for a stope in strip filling mining of a mine, including the following steps:

[0033] S1. Strip division:

[0034] The roof of the mine in this embodiment belongs to an extremely stable roof. The panel to be mined is divided into 10 strips, the width of each strip is 10 m, and the direction of each strip is perpendicular to the strike of the ore body, as Figure 4 shown.

[0035] S2. Stoping:

[0036] When the first strip is stoped, the cut raise is used as the working space, and the first strip is stoped upward. After the stoping of the first strip is completed, the second strip is continuously stoped; when the Nth strip is stoped, the goaf formed by the stoping of the (N - 1)th strip is used as the working space, and the Nth strip is stoped upward. After the stoping of the Nth strip is completed, the (N + 1)th strip is continuously stoped; the stoping time of each strip is 5 days; N is an integer greater than or equal to 2.

[0037] S3. Waste rock grouting filling:

[0038] After the mining of the Kth strip is completed, the void formed after the mining of the (K - 1)th strip is filled with waste rock grouting in the upward direction along the strip; the time for waste rock grouting filling for each strip is 4 days; K is an even number greater than or equal to 2.

[0039] S4. Laying a waste rock bottom:

[0040] After the mining of the first strip is completed, in the void formed after the mining of the last strip in the upper panel, a layer of waste rock bottom body 4 is poured with waste rock concrete; after the mining of the (K + 1)th strip is completed, in the void formed after the mining of the Kth strip, a layer of waste rock bottom body 4 is poured with waste rock concrete; the time from the start of pouring the waste rock bottom body 4 to the initial setting of the waste rock bottom body 4 for each strip is 2 days.

[0041] S5. Backfill with tailings:

[0042] After the waste rock bottom body 4 of the Kth strip reaches initial setting, the void formed after the mining of the Kth strip is filled with upward cemented tailings along the strip; the time for cemented tailings filling for each strip is 3 days.

[0043] In the mine of this embodiment, the elastic modulus E1 of the waste rock cemented filling body 2 is 2440 MPa, the elastic modulus E2 of the cemented tailings filling body 3 is 423 MPa, the stope height h is 6 m, the uniaxial compressive strength σ1 of the waste rock strip is 31 MPa, and the uniaxial compressive strength σ2 of the tailings strip is 5 MPa. Then the thickness of the waste rock bottom body 4 is:

[0044] = 0.54 m Embodiment 2

[0045] This embodiment of the present invention discloses a stress coordination method for a stope in strip filling mining of a mine. The difference between this embodiment and Embodiment 1 is as follows:

[0046] The roof of the mine in this embodiment is a relatively stable roof. The panel to be mined is divided into 20 strips, and the width of each strip is 5 m.

[0047] In this embodiment, the mining time for each strip in the mining step is 4 days, the waste rock grouting filling time for each strip in the waste rock grouting filling step is 4 days, the time from the start of pouring the waste rock bottom body 4 to the initial setting of the waste rock bottom body 4 for each strip in the waste rock bottom laying step is 1.5 days, and the cemented tailings filling time for each strip in the tailings filling step is 2.5 days.

[0048] In the mine of this embodiment, the elastic modulus E1 of the waste rock cemented filling body 2 is 1980 MPa, the elastic modulus E2 of the tailings cemented filling body 3 is 380 MPa, the stope height h is 9 m, the uniaxial compressive strength σ1 of the waste rock strip is 25 MPa, and the uniaxial compressive strength σ2 of the tailings strip is 4 MPa. Then the thickness of the waste rock bottom layer 4 is:

[0049] =2.22 m

[0050] Other contents of this embodiment are the same as those of Embodiment 1 and will not be elaborated here.

[0051] In Embodiment 1 and Embodiment 2, a layer of waste rock bottom layer 4 is pre-cast with waste rock concrete at the bottom of the tailings cemented filling body 3. If the tailings cemented filling body 3 and the waste rock bottom layer 4 are regarded as a whole, the equivalent elastic modulus of the whole tailings filling strip 6 is increased, which will provide a stronger support effect for the roof, mobilize the bearing capacity of the tailings filling strip 6 itself, and can relieve the pressure on the waste rock filling strip 5, transfer part of the load to the tailings cemented filling body 3, coordinate the stress state of the composite structure, improve the bearing efficiency of the tailings cemented filling body 3, and reduce the filling cost.

[0052] The stress coordination method of the present invention that neither changes the strength of the waste rock filling body, nor changes the elastic modulus of the waste rock or tailings filling body, and can effectively transfer part of the load to the tailings filling body improves the bearing efficiency of the filling body and reduces the filling cost.

[0053] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the method part.

[0054] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A stress coordination method for a stope in strip filling mining of a mine, characterized in that, It includes the following steps: S1. Strip division: According to the stability of the roof, the to-be-mined panel is divided into an even number of strips, and each strip is perpendicular to the strike of the ore body; the division of the even number of strips forms symmetric stress coordination units, so that the waste rock filling strips and the tailings filling strips are distributed alternately; the width of each strip is 5 - 10 m; S2. Stoping: Upward stoping is carried out in sequence from the first strip to the Nth strip; N is an integer greater than or equal to 2; when stoping the first strip, the cutting raise is used as the working space, and upward stoping is carried out along the first strip; when stoping the Nth strip, the goaf formed by stoping the (N - 1)th strip is used as the working space, and upward stoping is carried out along the Nth strip; after stoping the Nth strip, continue to stop the (N + 1)th strip; S3. Waste rock grouting filling: After stoping the Kth strip, upward waste rock grouting filling is carried out along the strip for the goaf formed after mining the (K - 1)th strip; K is an even number greater than or equal to 2; S4. Waste rock bottom paving: After stoping the (K + 1)th strip, in the goaf formed after mining the Kth strip, a layer of waste rock bottom paving body is poured with waste rock concrete; the thickness of the waste rock bottom paving body is: where l is the thickness of the waste rock bottom paving body, m; σ1 is the uniaxial compressive strength of the waste rock strip, MPa; σ2 is the uniaxial compressive strength of the tailings strip, MPa; E1 is the elastic modulus of the waste rock cemented filling body, MPa; E2 is the elastic modulus of the tailings cemented filling body, MPa; h is the stope height, m; S5. Tailings filling: After the waste rock bottom paving body of the Kth strip starts to set, upward tailings cemented filling is carried out along the strip for the goaf formed after mining the Kth strip.

2. The stress coordination method for a stope in strip filling mining of a mine according to claim 1, characterized in that, In step S4, after stoping the first strip, a layer of waste rock bottom paving body is poured with waste rock concrete in the goaf formed after mining the last but one strip in the upper panel.

3. The stress coordination method for a stope in strip filling mining of a mine according to claim 1, characterized in that In step S2, the stoping time for each strip is M1 days; in step S3, the waste rock grouting filling time for each strip is M2 days; in step S4, the time from the start of pouring the waste rock bottom paving body to the initial setting of the waste rock bottom paving body for each strip is M3 days; in step S5, the tailings cemented filling time for each strip is M4 days.

4. A stress coordination method for a stope in strip filling mining of a mine according to claim 3, characterized in that, M1 is 4 or 5 days; M2 is 4 days; M3 is 1.5 or 2 days; M4 is 2.5 or 3 days.

5. The stress coordination method for a stope in strip filling mining of a mine according to claim 3 or 4, characterized in that M2 ≤ M1, M3 + M4 ≤ M1.

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