A calculation method for overburden separation caused by mining based on equivalent subsidence

Abstract

The present invention proposes a method for calculating overburden separation due to mining based on equivalent sinking, which belongs to the field of mining subsidence prediction, overburden separation grouting and rock layer control in the field of mining engineering. The method first calculates the mining sinking value of each rock layer in the mining working face; starting from the first rock layer under the topsoil layer, the mining sinking value of each rock layer is subtracted from the mining sinking value of the rock layer above the rock layer to obtain the overburden separation amount of each rock layer; the rock layers are sorted in order from large to small according to the separation amount, and the rock layer corresponding to the maximum value of the separation amount in the sequence is taken as the current rock layer; the current rock layer is judged to determine the rock layer position of the overburden separation grouting. The present invention can conveniently calculate the separation amount and separation layer position of the overburden layer, providing a concise judgment basis for the design and implementation of overburden separation grouting and sinking reduction.

Description

Technical Field

[0001] The invention belongs to the field of mining subsidence prediction, overburden stratum grouting subsidence reduction and rock stratum control in the field of mining engineering, and specifically relates to a mining-induced overburden stratum grouting calculation method based on equivalent subsidence. Background Art

[0002] Backfill mining is an effective means to control overburden and surface subsidence, reduce damage to land and ecological environment, and is an important way to achieve green and sustainable development in mining areas. Backfill mining includes two types: backfilling in goaf and backfilling in overburden separation. Backfilling in goaf can be further divided into water-sand filling, gangue self-flowing filling, high-water material filling, solid compaction filling, etc. Although backfilling in goaf can achieve a good effect of controlling overburden and surface movement, it also has disadvantages such as parallel filling system and production system, complex process, and high cost. Grouting in overburden separation uses ground drilling as a filling channel and uses fly ash, slag, etc. from power plants as filling materials. The filling system is separated from the production system and does not interfere with each other. When the grouting layer is selected accurately and the grouting timing is timely, a good overburden movement control effect can be achieved. The difficulty of grouting in overburden separation lies in the determination of the separation layer position and separation amount. Most of the current determination methods use the key layer theory of rock strata control to determine the delamination position through complex mechanical calculations, but it is still difficult to quantitatively determine the delamination amount; in addition, there are also numerical simulation methods such as finite element, boundary element, discrete element, and fast Lagrangian analysis for calculation and judgment. Due to the limitations of boundary conditions and the uncertainty of the selection of physical and mechanical parameters, it often requires certain engineering experience and repeated debugging, and the simulation calculation results are not satisfactory. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology and propose a method for calculating the delamination of the overburden layer caused by mining based on equivalent subsidence. The present invention can conveniently calculate the delamination amount and delamination layer position of the overburden layer, and provide a concise judgment basis for the design and implementation of grouting to reduce subsidence in the delamination layer of the overburden layer.

[0004] The present invention proposes a method for calculating the separation of overburden caused by mining based on equivalent subsidence, comprising:

[0005] Calculate the mining subsidence value of each rock layer in the mining working face;

[0006] Starting from the first rock layer under the surface soil layer, the mining settlement value of each rock layer is subtracted from the mining settlement value of the upper rock layer to obtain the overburden separation amount of each rock layer;

[0007] The rock layers are sorted in descending order according to the delamination amount, and the rock layer corresponding to the maximum delamination amount in the sequence is taken as the current rock layer;

[0008] Determine the current rock formation to determine the rock formation position for overburden separation grouting;

[0009] Wherein, for the jth rock layer from the surface downward, the calculation expression of the mining subsidence value is as follows:

[0010]

[0011] In the formula, x o The reference point p set for the mining face surface o The coordinates of point p o The sinking value is w o (x o ); point p o The overburden point of the jth rock layer corresponding to the direction of movement toward the goaf The coordinates are Overburden point The sinking value is b is the width of the mining face; δ0 is the comprehensive boundary angle between the overburden and the surface movement; h i is the thickness of the i-th rock layer from the surface downward, i = 1, 2, ..., n, n is the total number of rock layers; when i = 1, h1 represents the thickness of the topsoil layer; is the mining depth; It represents the cumulative depth from the ground surface to the bottom interface of the jth rock layer, j=0,1,2,3,…,n; when j=0, h0=0.

[0012] In a specific embodiment of the present invention, judging the current rock formation to determine the rock formation position for overburden separation grouting includes:

[0013] If the height of the bottom interface of the current rock layer from the bottom of the mining layer roof is less than the height value of the water-conducting fracture zone, the separation layer of the current rock layer is an invalid separation layer, and the current rock layer is removed from the sequence; the rock layer corresponding to the maximum separation value is selected from the updated sequence as the new current rock layer, and then the current rock layer is re-determined;

[0014] If the height of the bottom interface of the current rock layer from the bottom of the mining layer roof is greater than or equal to the height value of the water-conducting fracture zone, the separation layer of the current rock layer is an effective separation layer, and the separation layer is used as the overburden separation layer grouting layer;

[0015] If, after the sequence is traversed, all the separation layers of the rock layers are invalid separation layers, the overburden separation layer grouting cannot be performed on the mining working face.

[0016] In a specific embodiment of the present invention, the height value calculation expression of the water-conducting fracture zone is as follows:

[0017]

[0018] In the formula, H 导 is the height of the water-conducting fracture zone, ∑M is the cumulative mining thickness;

[0019] H 导 The upper limit value of is taken as the final height value of the water-conducting fracture zone.

[0020] The characteristics and beneficial effects of the present invention are:

[0021] The present invention proposes a method for calculating the delamination of overburden rock caused by mining based on equivalent subsidence. The method involves few parameters in the calculation, and is only related to the width of the working face, mining depth, rock layer thickness, rock layer burial depth, and the comprehensive boundary angle between the overburden rock and the surface movement. It does not involve the physical and mechanical properties of each rock layer, and can reflect the influence of the mining degree; the calculation process is simple. The subsidence of each rock layer can be easily calculated, and the delamination amount can be obtained by using the inconsistent subsidence of adjacent rock layers; by eliminating invalid delamination, effective closed delamination layers and layers can be obtained, providing technical criteria for delamination grouting to reduce subsidence. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is an overall flow chart of a method for calculating overburden separation caused by mining based on equivalent subsidence in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The present invention proposes a method for calculating overburden separation caused by mining based on equivalent subsidence. The present invention will be further described in detail below in conjunction with specific embodiments.

[0024] The present invention proposes a method for calculating the separation of overburden caused by mining based on equivalent subsidence. The overall process is as follows: Figure 1 As shown, the following steps are included:

[0025] 1) Calculate the mining subsidence value of each rock layer according to the geological mining conditions of the mining working face;

[0026] Among them, for the jth rock layer from the surface downward, the calculation expression of its subsidence value is as follows:

[0027]

[0028] In the formula, the center of the surface subsidence basin is taken as the coordinate origin, and any point p on the surface of the mining working face is o The coordinates are x o , point p o As a reference point, point p o The sinking value is recorded as w o (x o ); surface point p o The overburden point of the jth rock layer corresponding to the direction of movement toward the goaf The coordinates of Overburden point The sinking value is recorded as It should be noted that, in the present invention, each rock layer is calculated with reference to a certain surface point p o Calculation is performed, but the corresponding overburden point coordinates on different buried depth rock layers are different, that is, for the same surface point p o , for n rock layers, there are n p s point, p of each rock layer s The point coordinates are different.

[0029] b is the width of the mining face, in meters; δ0 is the comprehensive boundary angle between the overburden and the surface movement, in degrees; h i is the thickness of the i-th rock layer from the surface downward, i = 1, 2, ..., n, n is the total number of rock layers; when i = 1, h1 represents the thickness of the topsoil layer, in meters; is the mining depth in meters, which is a certain value; It represents the cumulative depth from the ground surface to the bottom interface of the jth rock layer (this depth is also the cumulative depth from the ground surface to the top interface of the j+1th rock layer), j=0,1,2,3,…,n; when j=0, h0=0, representing the calculated depth is the ground surface; when j=1, The calculated depth represented by is the cumulative depth of the bottom interface of the first rock layer, i.e. the topsoil layer (also the top interface of the second rock layer), in meters; when j = n, It is equal to the mining depth, in meters, representing the cumulative depth from the surface to the bottom interface of the nth rock layer (i.e., the bottom of the roof of the mining layer, which is the mining coal seam in this embodiment).

[0030] 2) Using the results of step 1), calculate the amount of overburden separation of each rock layer.

[0031] Since the same rock layer has integrity, the subsidence is the same; however, the subsidence of rock layers at different levels is inconsistent. Starting from the first rock layer under the topsoil layer, the subsidence value of the rock layer minus the subsidence value of the upper rock layer of the rock layer is the overburden delamination amount of the rock layer, where the upper rock layer is the adjacent rock layer located above the rock layer.

[0032] 3) Sort the rock layers in descending order of the delamination amount, and take the rock layer corresponding to the maximum delamination amount in the sequence as the current rock layer;

[0033] 4) Determine the rock layer location for overburden separation grouting by judging the current rock layer.

[0034] The specific method is:

[0035] 4-1) Calculate the height of the water-conducting fracture zone according to the empirical formula in the "Specifications for Coal Pillar Retention and Coal Compressed Mining in Buildings, Water Bodies, Railways and Main Wells and Lanes". For hard overburden, the expression is as follows:

[0036]

[0037] In the formula, H 导 is the height of the water-conducting fracture zone, in meters; ∑M is the cumulative mining thickness, in meters.

[0038] 4-2) Judgment:

[0039] If the height of the bottom interface of the current rock layer from the bottom of the mining layer roof is less than the height value of the water-conducting fracture zone (in this embodiment, the upper limit value calculated by formula (2) is used as the height value of the water-conducting fracture zone), the separation layer of the current rock layer is an invalid separation layer, and the rock layer is removed from the sequence obtained in step 3), and the rock layer corresponding to the maximum separation value is selected from the updated sequence as the new current rock layer, and then the process returns to step 3-4);

[0040] If the height of the bottom interface of the current rock layer from the bottom of the mining layer roof is greater than or equal to the height of the water-conducting fracture zone, the separation layer of the current rock layer is an effective separation layer, and the separation layer is used as the grouting layer of the overburden separation layer.

[0041] If, after the sequence traversal is completed, all the separation layers of the current rock layer are invalid separation layers, grouting of the overburden separation layer cannot be carried out on this working face.

[0042] The method of the present invention is further described in detail below with reference to a specific embodiment.

[0043] In a specific embodiment of the present invention, the mining face is 80 meters wide, the strike reaches full mining, the mining depth is 200 meters, and the width-to-depth ratio is 0.4; the mining thickness is 2 meters, and the comprehensive boundary angle δ0 between the overburden and the surface movement is 65°. The lithology of the overburden strata from the surface to the top plate is shown in the second column of Table 1, which is mainly sandstone and siltstone, with a unidirectional tensile strength of 55 MPa, and is a hard rock stratum; the thickness of each rock stratum is shown in the third column of Table 1, and the cumulative depth is shown in the fourth column of Table 1.

[0044] This embodiment proposes a method for calculating overburden separation caused by mining based on equivalent subsidence, including the following steps:

[0045] 1) Calculate the mining subsidence value of each rock layer according to the geological mining conditions of the mining working face;

[0046] In this embodiment, after the coal seam is mined, the mining sinking is transmitted from the roof to the overlying rock layer, and the roof falls and accumulates in the goaf in the form of collapse. The roof sinks 2000 mm, which is equal to the mining thickness of the coal seam.

[0047] The subsidence value of each rock layer is calculated using formula (1). The results are shown in column 5 of Table 1.

[0048] 2) Using the results of step 1), calculate the amount of overburden separation of each rock layer.

[0049] Due to the inconsistency of subsidence of different strata, starting from the first rock layer under the topsoil layer, the subsidence value of the lower rock layer minus the subsidence value of the upper rock layer is the overburden separation amount of the lower rock layer. The results of the overburden separation amount of each rock layer in this embodiment are shown in the 6th column of Table 1.

[0050] 3) Sort the rock layers in descending order of the delamination amount, and take the lower rock layer corresponding to the maximum delamination amount in the sequence as the current rock layer;

[0051] It can be seen from the sixth column of Table 1 that after sorting, the maximum delamination value corresponds to the 39th shale layer, and its upper rock layer is the 38th siltstone layer. There will be a delamination of 138 mm between the 38th siltstone layer and the 39th shale layer; the second maximum delamination value corresponds to the 26th mudstone layer, and its upper rock layer is the 25th sandstone layer. There will be a delamination of 125 mm between the 25th sandstone layer and the 26th mudstone layer.

[0052] 4) Determine the rock layer location for overburden separation grouting by judging the current rock layer.

[0053] The specific method is:

[0054] 4-1) Calculate the height of the water-conducting fracture zone according to formula (2); in this embodiment, the height of the water-conducting fracture zone is calculated to be 45.45±8.9 meters, and the upper limit of the height of the water-conducting fracture zone is 54.35 meters.

[0055] 4-2) Judgment:

[0056] According to Table 1, when the 39th shale layer is taken as the current rock layer, the height of the bottom interface of the 39th shale layer from the bottom of the coal seam roof is 200-182=18 meters, which is less than the upper limit of the height of the water-conducting fracture zone, indicating that the 39th shale layer is located in the fracture zone. A closed filling space cannot be formed between the 38th siltstone layer and the 39th shale layer, so it is not considered and should be eliminated.

[0057] When the 26th mudstone layer is taken as the current rock layer, the bottom interface of the 26th mudstone layer is 200-134=66 meters away from the bottom of the coal seam roof, which is greater than the upper limit of the height of the water-conducting fracture zone. The 125 mm delamination layer between the 25th sandstone layer and the 26th mudstone layer can be selected as the overburden delamination layer grouting layer.

[0058] Table 1 Parameters of mining overburden separation in a specific embodiment of the present invention

[0059]

[0060]

Claims

1. A method for calculating overburden separation caused by mining based on equivalent subsidence, characterized in that: include: Calculate the mining subsidence value of each rock layer in the mining working face; Starting from the first rock layer under the surface soil layer, the mining settlement value of each rock layer is subtracted from the mining settlement value of the upper rock layer to obtain the overburden separation amount of each rock layer; The rock layers are sorted in descending order according to the delamination amount, and the rock layer corresponding to the maximum delamination amount in the sequence is taken as the current rock layer; Determine the current rock formation to determine the rock formation position for overburden separation grouting; Wherein, for the jth rock layer from the surface downward, the calculation expression of the mining subsidence value is as follows: In the formula, x o The reference point p set for the mining face surface o The coordinates of point p o The sinking value is w o (x o ); point p o The overburden point of the jth rock layer corresponding to the direction of movement toward the goaf The coordinates are Overburden point The sinking value is b is the width of the mining face; δ0 is the comprehensive boundary angle between the overburden and the surface movement; h i is the thickness of the i-th rock layer from the surface downward, i = 1, 2, ..., n, n is the total number of rock layers; when i = 1, h1 represents the thickness of the topsoil layer; is the mining depth; It represents the cumulative depth from the ground surface to the bottom interface of the jth rock layer, j=0,1,2,3,…,n; when j=0, h0=0.

2. The method according to claim 1, characterized in that The current rock formation is judged to determine the rock formation position for overburden separation grouting, including: If the height of the bottom interface of the current rock layer from the bottom of the mining layer roof is less than the height value of the water-conducting fracture zone, the separation layer of the current rock layer is an invalid separation layer, and the current rock layer is removed from the sequence; the rock layer corresponding to the maximum separation value is selected from the updated sequence as the new current rock layer, and then the current rock layer is re-determined; If the height of the bottom interface of the current rock layer from the bottom of the mining layer roof is greater than or equal to the height value of the water-conducting fracture zone, the separation layer of the current rock layer is an effective separation layer, and the separation layer is used as the overburden separation layer grouting layer; If, after the sequence is traversed, all the separation layers of the rock layers are invalid separation layers, the overburden separation layer grouting cannot be performed on the mining working face.

3. The method according to claim 2, characterized in that The calculation expression of the height value of the water-conducting fracture zone is as follows: In the formula, H 导 is the height of the water-conducting fracture zone, ∑M is the cumulative mining thickness; H 导 The upper limit value of is taken as the final height value of the water-conducting fracture zone.

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