High-stage step-by-step safe mining construction method suitable for I-shaped jambs

Abstract

The invention discloses a high-stage step-by-step safe mining construction method suitable for an I-shaped jamb, which comprises the following steps: S1, step-by-step stoping area division: dividing the jamb into a plurality of stoping units along the trend according to the geometrical shape of the jamb and the strength difference of filling bodies on the two sides, reserving 2m and 4m thick ore walls on the east side of the jamb at intervals, reserving 2m ore walls on the west side of the jamb, and reserving 4m ore walls in the middle of the jamb; s2, recovery and optimization of a mining preparation project; S3, staged drilling and blasting design; s4, reserving an ore wall and protecting a filling body; and S5, subsequent sublevel filling is conducted, specifically, after each stoping unit is completed, a cementing material with the cement-sand ratio being 1: (4-8) is adopted for filling in a layered mode, and a stress sensor is pre-buried in a filling body. The method solves the problems of instability of the filling body, uneven distribution of blasting energy and the like in high-stage pillar recovery, improves the pillar recovery rate, reduces the damage area of the filling body and reduces the support cost.

Description

Technical Field

[0001] The invention relates to the technical field of mining, and in particular to a high-stage step-by-step safe mining construction method suitable for an "I"-shaped mining pillar. Background Art

[0002] The Datuanshan deposit (IV plate area ore body) is a deeply buried blind ore body, which is located in the Xiaoliang Formation of the Lower Triassic. It is mainly controlled by geological strata and lithology. Its occurrence changes with the occurrence of the surrounding rock. The ore body is layered, with a relatively stable distribution and a relatively simple shape. It strikes 30° to 35° northeast and dips southeast with a medium dip. The dip varies slightly in different sections, generally 35° to 50°. The top plate is siliceous hornfels or hornfels intercalated with skarn, and some engineering rock bodies are marble. The bottom plate is biotite hornfels and plagioclase biotite hornfels. Fissures are developed in and around the ore body. Thick and large ore bodies are mainly above -610m.

[0003] The vertical pillar of the IV pan area is located in the thick part of the ore body. The pillar was originally within the design range of the pan area above -565m. It was left because the roof was too exposed and the stability became poor. The pillar is designed to be 25m wide. During the mining process of 33A and 33B, the roof became unstable. 1-3 rows of large holes were reserved without blasting. The widths of the above positions are 33m and 36m respectively (partial caving may have occurred, which should be explored during the construction of this project); this pillar is the design object of this time. The plane distribution range of the pillar is consistent with the mine room of the IV pan area (31A-35 lines), with a length of about 95m and a width of about 25-36m. It is located between the elevations of -507 and -604m in the vertical direction. The total ore volume of the pillar is about 498,600 tons, and the average geological grade is about 1.14%. The top of the spatial morphology of this pillar is basically at an elevation of -520m, the lower part is low in the north and high in the south, and the deepest part of 31B on the north side is basically above -580m.

[0004] Existing pillar mining mostly adopts the overall caving method or continuous mining method, which has the following problems: 1. When mining high-stage pillars (>50m), the bottom structure is subjected to excessive impact loads, which can easily lead to instability of the filling body; 2. When the strength difference between adjacent filling bodies is significant, traditional symmetrical mining is prone to cause collapse of the weak side filling body; 3. When the original mining project is restored, direct blasting and excavation can easily destroy the original support system and increase the risk of collapse; 4. The strength distribution of the filling body is unreasonable, making it difficult to form effective support. Therefore, the present application provides a high-stage step-by-step safe mining construction method suitable for "I"-shaped pillars to meet the needs. Summary of the invention

[0005] The purpose of this application is to provide a high-stage step-by-step safe mining construction method suitable for "I"-shaped pillars, which is used to solve the technical problems of filling body instability, collapse, inability to provide effective support and high risk of falling in the existing construction process.

[0006] To achieve the above purpose, the present application provides the following technical solutions: a high-stage step-by-step safe mining construction method suitable for "I"-shaped pillars, comprising the following steps; S1: Step-by-step mining area division: According to the geometric shape of the pillar and the strength difference of the filling bodies on both sides, the pillar is divided into several mining units along the strike, and 2m and 4m thick mine walls are left on the east side of the pillar, 2m mine walls are left on the west side, and 4m mine walls are left in the middle to form an "I"-shaped support structure; S2: Restoration and optimization of mining engineering, excavation and engineering transformation of the mining tunnels and rock drilling chambers in the original backfilled goaf, including shoveling the bottom, picking the top and expanding the side, so that the tunnel height reaches more than 3.5m, and the rock mass is supported by mesh spraying, pouring concrete or anchor rods, and the support strength is adjusted: S3: Staged rock drilling and blasting design, using two-stage downward deep hole drilling. The first stage of rock drilling depth does not exceed 45m. In the second stage, the blasting parameters are dynamically adjusted according to the stability of the filling body. The blasting height of each stage is controlled at 10-15m. S4: Mine wall retention and backfill protection, real-time monitoring of backfill deformation data during mining, and control of backfill exposure area to not exceed the critical value by adjusting the mine wall thickness and blasting sequence; S5: Subsequent segmented filling: After each mining unit is completed, cementing materials with a lime-sand ratio of 1:4 to 8 are used for layered filling, and stress sensors are embedded in the filling body to form a strength gradient distribution of the filling body.

[0007] Through phased mining (S3) and “I”-shaped support (S1), the single blasting height (10-15m) is reduced, stress concentration is dispersed, and the impact load on the bottom structure is reduced; The “I”-shaped mine wall (2m / 4m alternating on the east side, 2m on the west side, and 4m in the middle) provides differentiated protection for the low-strength filling body on the east side (1.29MPa) and the high-strength filling body on the west side (5.23MPa) to prevent collapse of the weak side. The drilling depth in the first stage does not exceed 45m. The borehole deviation rate increases significantly with the depth. After exceeding 45m, the borehole deviation may lead to uneven charging and unbalanced blasting energy distribution, affecting the fragmentation of ore. In addition, the downward deep hole needs to adopt segmented charging technology. If the hole depth exceeds 45m, the bottom charging density is difficult to control, and the "charge column separation" phenomenon is likely to occur, resulting in a decrease in the utilization rate of blasting energy. By shoveling the bottom, lifting the top and expanding the sidewalls (S2), the original tunnel is restored and the original support structure is retained, which reduces the amount of new excavation and construction risks; Improve the supporting effect of the filling body: Layered filling (S5) forms a strength gradient (layered 1:4~8 lime-sand ratio), enhances the bottom bearing capacity, and avoids overall failure of the filling body.

[0008] As a preferred implementation method in this embodiment, in S1, mining is arranged along the strike of the ore body, and mining is carried out continuously along the strike of the ore body. Due to the existing engineering restrictions in the middle section of -610m and the large amount of waste rock at the bottom, a large funnel bottom structure is used to mine. The funnel is formed by large-hole blasting, with a specification of 6m×6m, a height of 14-17m, and an inclination angle of the expansion bucket bell mouth ≥50°.

[0009] The large funnel structure (6m×6m) expands the ore outlet area and cooperates with the expansion bucket inclination angle ≥50° to prevent ore blockage and improve the smoothness of ore discharge. The funnel is formed by large-hole blasting to reduce the direct impact of blasting vibration on the filling body and protect the stability of the bottom structure.

[0010] As a preferred implementation in this embodiment, in S2, a bottom shoveling method is adopted to retain the integrity of the original support structure, the bottom shoveling depth does not exceed 1.5m, and the top height does not exceed 0.8m.

[0011] Limit the range of shoveling bottom and top to avoid damaging the original mesh spraying or poured concrete support, maintain the stability of the tunnel, utilize existing engineering renovations, reduce the amount of new support projects, and save costs by about 25%.

[0012] As a preferred implementation in this embodiment, in S3, an asymmetric charging structure is used for blasting, the charging coefficient close to the filling body side is reduced by 20%-30%, and the detonation sequence adopts a progressive detonation from high to low and from weak to strong.

[0013] Asymmetric charging reduces the blasting energy near the filling body, avoiding vibration-induced cracking of the filling body. The progressive detonation sequence guides the energy release to the free surface, reducing disturbance to the surrounding rock. As a preferred implementation in this embodiment, in S5, the strength gradient distribution of the filling body is achieved by layered filling, with the bottom layer filled with a 1:4 ash-sand ratio, the middle layer 1:6, and the upper layer 1:8, and the construction time between each layer is not less than 72 hours.

[0014] A high lime-sand ratio of 1:4 (high cement content) is used to ensure that the bottom filling body has sufficient compressive strength and stability. The compressive strength of the filling body with a lime-sand ratio of 1:4 can reach more than 4.5MPa, which can effectively support the pressure of the upper pillars and surrounding rocks and prevent the bottom structure from becoming unstable; The middle filling body is located between the bottom layer and the upper layer. It must bear a certain upper pressure and provide support for the upper filling body. The design of 1:6 lime-sand ratio not only ensures a certain strength but also takes into account economy. The compressive strength of the filling body with 1:6 lime-sand ratio is about 3.0MPa, which can effectively share the upper pressure and provide stable support for the upper filling body. The middle filling body, as a transition layer between the bottom layer and the upper layer, can balance the stress distribution of the upper and lower layers and avoid local damage caused by stress concentration. The upper filling body is subjected to relatively small pressure, and its main function is to seal the empty area and prevent the upper surrounding rock from falling. Therefore, a low ash-sand ratio of 1:8 (low cement content) is used to save material costs; Through layered design, high lime-sand ratio filling is only used in the bottom layer, and the lime-sand ratio is gradually reduced in the middle and upper layers, which significantly reduces the amount of cement used and reduces the filling cost. The layered filling design can save about 15%-20% of the filling material cost.

[0015] As a preferred implementation in this embodiment, in S2, when the RQD value of the rock mass is less than 50%, anchor rod + mesh spraying support is adopted, and the anchor rod spacing is 1.2m. When the RQD value is greater than 80%, only concrete pouring support is adopted.

[0016] For low RQD rock mass (broken zone), anchor bolts + mesh spraying are used to enhance the support strength. For high RQD rock mass (complete), support is simplified and materials are saved. Adjusting the support plan according to the RQD value can reduce redundant operation time by about 30%.

[0017] As a preferred implementation in this embodiment, in S1, the ore pillars are divided into multiple stages in the vertical direction, and the method of empty field and subsequent filling in the downward large hole stage is adopted to collapse the ore in the order of "center to both ends and backward".

[0018] The backward caving sequence gradually reduces the free surface, reduces the risk of filling body exposure, and central detonation forms a stable free surface, reducing the hazards of blasting flying rocks and shock waves.

[0019] As a preferred implementation method in this embodiment, the ore pillar is divided vertically into 4 stages, each stage is 10m high, and a downward deep hole backward caving method is adopted. The step distance of each caving is 5m, starting from the 33A line grooving chamber, backward lateral caving is carried out from the center to both ends along the direction of the ore pillar.

[0020] It is divided into 4 stages, each stage is designed with a height of 10m and a step distance of 5m, to ensure that the energy of each blasting is controllable, reduce over-excavation or under-excavation, and the backward caving sequence reduces ore residue, and the recovery rate is increased to more than 92%.

[0021] In summary, the technical effects and advantages of the present invention are as follows: The invention has a reasonable structure and adopts technologies such as step-by-step mining, mine wall retention, asymmetric blasting and gradient filling to solve the problems of filling body instability and uneven blasting energy distribution in high-stage pillar mining, and improves the pillar recovery rate, reduces the filling body damage area and reduces the support cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is the construction plan of Datuanshan-610m; Figure 2 for Figure 1 Middle AA section; Figure 3 for Figure 1 Sectional view along line 33A. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Taking the mining of the -610m vertical pillar in the IV plate area of ​​the Datuanshan mining section as an example, the mining includes the following steps: S1: According to the geometric shape of the pillar (95m long × 25-36m wide), it is divided into 4 mining units (each unit is about 24m), with 2m and 4m mine walls left alternately on the east side, 2m mine wall left on the west side, and 4m mine wall left in the middle, forming an "I"-shaped support; Effect verification: The pillar stability monitoring showed that the displacement on the east and west sides was <5mm and no collapse occurred.

[0026] S2: The -565m mine tunnel was shoveled to the bottom (depth 1.2m) and top (height 0.6m), raised to 3.5m, and supported by bolts + mesh spraying (RQD=45% area), with bolt spacing of 1.2m; only concrete support was used in the RQD=85% area; Effect verification: tunnel deformation <3mm, support cost reduced by 18%.

[0027] S3: In the first stage, the drilling depth is 45m, the hole diameter is 165mm, and the charge density is 0.8kg / m³; in the second stage, according to the monitoring data of the filling body (deformation <2mm), the charge coefficient is adjusted to 70% (filling body side): Effect verification: After blasting, the qualified rate of ore block size (<300mm) reached 90%, and there was no cracking in the filling body.

[0028] S4: Real-time monitoring of filling deformation data during mining, and control of filling exposure area to not exceed the critical value by adjusting the mine wall thickness and blasting sequence; The ash-sand ratio of the S5 bottom layer is 1:4 (compressive strength 4.5MPa), the middle layer is 1:6 (3.0MPa), and the upper layer is 1:8 (2.0MPa). The embedded stress sensor shows that the stress concentration factor of the bottom layer is reduced to 1.2 (originally 1.8).

[0029] Effect verification: The overall stability of the filling body is improved, and there is no sinking phenomenon.

[0030] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A high-stage step-by-step safe mining construction method suitable for "I"-shaped pillars, characterized in that: The method comprises the following steps: S1: Step-by-step mining area division: According to the geometric shape of the pillar and the strength difference of the filling bodies on both sides, the pillar is divided into several mining units along the strike, and 2m and 4m thick mine walls are left on the east side of the pillar, 2m mine walls are left on the west side, and 4m mine walls are left in the middle to form an "I"-shaped support structure; S2: Restoration and optimization of mining engineering, excavation and engineering transformation of the mining tunnels and rock drilling chambers in the original backfilled goaf, including shoveling the bottom, picking the top and expanding the side, so that the tunnel height reaches more than 3.5m, and the rock mass is supported by mesh spraying, pouring concrete or anchor rods, and the support strength is adjusted: S3: Staged rock drilling and blasting design, using two-stage downward deep hole drilling. The first stage of rock drilling depth does not exceed 45m. In the second stage, the blasting parameters are dynamically adjusted according to the stability of the filling body. The blasting height of each stage is controlled at 10-15m. S4: Mine wall retention and backfill protection, real-time monitoring of backfill deformation data during mining, and control of backfill exposure area to not exceed the critical value by adjusting the mine wall thickness and blasting sequence; S5: Subsequent segmented filling: After each mining unit is completed, cementing materials with a lime-sand ratio of 1:4 to 8 are used for layered filling, and stress sensors are embedded in the filling body to form a strength gradient distribution of the filling body.

2. According to claim 1, a high-stage step-by-step safe mining construction method suitable for "I"-shaped pillars is characterized by: In S1, mining is arranged along the strike of the ore body, and continuous mining is carried out upward along the strike of the ore body. Due to the existing engineering restrictions in the middle section of -610m, the lower waste rock is large, so a large funnel bottom structure is used to mine. The funnel is formed by large-hole blasting, with a specification of 6m×6m, a height of 14-17m, and an inclination angle of the expansion bucket bell mouth ≥50°.

3. According to claim 1, a high-stage step-by-step safe mining construction method suitable for "I"-shaped pillars is characterized by: In S2, the bottom shoveling method is adopted to retain the integrity of the original support structure, the bottom shoveling depth does not exceed 1.5m, and the top height does not exceed 0.8m.

4. According to claim 1, a high-stage step-by-step safe mining construction method applicable to an "I"-shaped pillar is characterized by: In the S3, an asymmetric charging structure is used for blasting, the charging coefficient close to the filling body is reduced by 20%-30%, and the detonation sequence adopts a progressive detonation from high to low and from weak to strong.

5. According to claim 1, a high-stage step-by-step safe mining construction method suitable for "I"-shaped pillars is characterized by: In S5, the strength gradient distribution of the filling body is achieved by layered filling, with the bottom layer being filled with a 1:4 lime-sand ratio, the middle layer 1:6, and the upper layer 1:8, with the construction time between each layer being no less than 72 hours.

6. The high-stage step-by-step safe mining construction method applicable to an “I”-shaped pillar according to claim 1 is characterized by: In S2, when the RQD value of the rock mass is less than 50%, anchor bolt + mesh spraying support is adopted, and the anchor bolt spacing is 1.2m. When the RQD value is greater than 80%, only concrete pouring support is adopted.

7. The high-stage step-by-step safe mining construction method applicable to an “I”-shaped pillar according to claim 1 is characterized by: In S1, the ore pillars are divided into multiple stages in the vertical direction, and the method of empty field and subsequent filling in the downward large hole stage is adopted, and the ore is collapsed in the order of "center to both ends and backward".

8. The high-stage step-by-step safe mining construction method applicable to an “I”-shaped pillar according to claim 7 is characterized by: The pillars are divided vertically into four stages, each with a height of 10m. Downward deep-hole backward caving is adopted, with a step distance of 5m each time. Starting from the 33A line slot chamber, backward lateral caving is carried out from the center to both ends along the direction of the pillars.

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