Double-layer treatment method for collapse column

Abstract

The invention provides a collapse column double-layer treatment method which comprises the following steps: arranging N1 hole branches on one side, and arranging the N1 hole branches in parallel along the trend of a working surface of an upper rock stratum; n2 hole branches are arranged on the other side and are arranged in parallel along the trend of the working surface of the lower rock stratum; and a C39 lime control area, a C33 lime control area and a comprehensive control area are formed according to specific hole branches, stratum cracks in the range of the collapse column control area are well filled and reinforced, the design purpose of grouting control is achieved, and the grouting quality is qualified. The modes of up-down exploration and double-layer grouting treatment are implemented in the treatment range of the influence area of the collapse column, the tracks of the upper layer and the lower layer are arranged in a large-angle intersection mode, the overlapping area of the two target layers is the effective treatment plane range of the collapse column, and full coverage and no blind area of the design treatment range are achieved, and the design requirement is exceeded. Cement chippings exist in drilling rock debris in later construction, the drilling slurry absorption amount is obviously reduced, stratum cracks in the collapse column treatment area range are well filled and reinforced, and the design purpose of grouting treatment is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining, and in particular to a double-layer treatment method for a collapsed column. Background Art

[0002] The underground coal seam conditions in coal mines are complex, and the geological structure is complex and changeable. In the process of mining, geological structures such as faults and collapse columns are often encountered. The so-called collapse column is due to the movement of the strata, and irregular rock bodies are embedded in the coal seam due to collapse. Caves are very common in limestone. Due to the continuous dissolution of groundwater, the caves are getting bigger and bigger. Under the long-term action of geological tectonic forces and the gravity of the upper covering rock layers, some caves collapse, and the coal-bearing strata covering the upper part also collapse, so the coal seam is damaged. Because this collapse is a round or irregular elliptical column, it is called a collapse column.

[0003] As a structurally broken geological body, karst collapse columns are good water storage and water conduction channels. The existence of karst collapse columns in mining areas not only affects the distribution of coal resources, but also affects mining design and safe mining.

[0004] At present, there are three main methods for fully mechanized mining faces to pass through subsidence columns during coal mining: moving and skipping, digging and bypassing, and direct hard passing. For subsidence columns with strong water content, it is necessary to leave protective coal pillars to ensure safety, and generally the methods of moving and skipping and digging and bypassing are used to pass through. According to the strength of the rock of the subsidence column, the direct hard passing method can be roughly divided into two types: passing through hard subsidence columns and soft subsidence columns.

[0005] At present, the only way to directly pass through soft collapsed columns is to reinforce them with grouting. Since soft collapsed columns are often filled and cemented with mud, but the cementation is poor, the overall mechanical properties are very poor, and they do not have the bearing capacity themselves, so direct passage will cause leakage, resulting in the occurrence of roof collapse accidents on the working face. At the same time, when the support passes through, the support base sinks due to the soft bottom plate of the collapsed column and poor bearing capacity, which seriously affects safety and production progress. The collapsed column grouting method currently used is usually to grout the collapsed column without distinction, that is, the grouting time, slurry type and reinforcement area are not distinguished, which causes many problems. As for the grouting time, since the integrity and stress state of the collapsed column and the surrounding rock formations are different from those of ordinary rock formations, when the working face approaches the collapsed column, it will cause stress changes in the collapsed column, causing disturbance and damage to the column. If the grouting time is not appropriate, it will not have the effect of reinforcement. For the injected slurry and the reinforced area, if the reinforced area is injected with the same slurry, although the strength of the collapse column is improved, the strength of the collapse column cutting area and the corresponding top and bottom plates are equal, which increases the difficulty of cutting the area and even forms an artificial "hard collapse column", which needs to be treated again by the hard collapse column direct hard pass method. If the overall grouting strength is too high to be cut, and the strength is too low to ensure safe passage, this greatly increases the workload and cost, wastes materials, and reduces efficiency and safety.

[0006] After searching, the Chinese invention patent with application number "CN201510103932.3" discloses a method of reinforcing the collapse column by grouting in different levels and zones so that the fully mechanized mining face can directly pass through the soft collapse column. It belongs to the field of coal mining technology. On the basis of exploration and drainage, the collapse column is first divided into: roof reinforcement area, cutting area and floor reinforcement area; then, according to the shape, size, position and reinforcement thickness of the collapse column, the drilling holes are reasonably arranged, and the slurry with corresponding material ratio is injected into each area respectively. Grouting improves the cementation of the rock inside the collapse column, so that the collapse column rock in different areas can achieve the required mechanical properties and bearing capacity; then, when the working face approaches the collapse column, the mining height is reduced to slow down the intensity of the roof activity, reduce the advance support pressure on the collapse column, and enable the fully mechanized mining face to directly pass through the collapse column. Compared with the existing method of reinforcing the collapse column by grouting so that the fully mechanized mining face can directly pass through the collapse column, this method greatly reduces the workload, material waste and cost, and improves production efficiency and safety.

[0007] However, it was found during actual use that the above-mentioned method of reinforcing the collapse column by graded and zoned grouting to enable the comprehensive mining face to pass directly through the soft collapse column requires the formation of a roof reinforcement zone, a cutting zone and a bottom plate reinforcement zone in the collapse column, and drilling and grouting are carried out in different zones of the collapse column, which cannot meet the full coverage and no blind spot requirements of the treatment range; at the same time, drilling holes at different angles needs to pass through different rock formations, resulting in deviations that make accurate grouting impossible and great difficulty in drilling.

[0008] In summary, there is an urgent need for a double-layer treatment method for collapse columns to solve the above problems. Summary of the invention

[0009] In order to make up for the above shortcomings, the present invention provides a double-layer treatment method for collapse columns, which is used to solve the above-mentioned existing method of graded and zoned grouting to reinforce collapse columns so that the comprehensive mining face can directly pass through the soft collapse columns. It is necessary to form a top plate reinforcement area, a cutting area and a bottom plate reinforcement area in the collapse column, and drilling and grouting are carried out in different zones of the collapse column, which cannot meet the full coverage and no blind spot requirements of the treatment range; at the same time, drilling holes at different angles need to pass through different rock formations, resulting in deviations that make accurate grouting impossible and drilling difficult.

[0010] The present invention is achieved in that:

[0011] A double-layer treatment method for a collapsed column comprises the following steps:

[0012] S1. Determine the rock physical and mechanical parameters in the coal roof, floor and rock formations through geophysical exploration or drilling;

[0013] S2. Determine the boundary of the collapse column and the water content in the collapse column through geophysical exploration or drilling, and drain the water;

[0014] S3. Sampling and analysis: drilling and sampling of the collapse column rock, logging of rock cuttings and sand sampling, and determination of the natural uniaxial compressive strength, porosity, water content and permeability coefficient of the samples;

[0015] S4. Partition and predict the physical and mechanical parameters of each area after reinforcement: that is, determine the partition according to the oblique side structure of the two sides of the collapse column and the rock structure: one side is set as the N1 hole branch, arranged parallel to the working surface of the upper rock layer; the other side is set as the N2 hole branch, arranged parallel to the working surface of the lower rock layer; and form C3 according to the specific hole branch 9 Ash control area, C3 3下 Ash control area and comprehensive control area;

[0016] S5. Simulated grouting test: Based on the physical and mechanical parameters of the consolidation bodies in the three areas obtained in S4, simulated grouting tests are carried out on the collapsed column samples with slurries of different types and proportions to determine the type and proportion of the slurry.

[0017] S6. Determine the spacing of the grouting holes in the top plate reinforcement area based on the porosity and permeability of the collapse column measured in S3, and then determine the setting time and grouting pressure, and select the grouting machine.

[0018] S7, N1 hole branch and N2 hole branch are grouting synchronously: firstly, the corresponding slurry determined by S5 is injected into the corresponding Taiyuan Formation 9 ash treatment area and Taiyuan Formation 3 lower ash treatment area of ​​the collapse column;

[0019] The N1 hole branch and the N2 hole branch are grouting simultaneously by drilling and grouting.

[0020] S8. Use the observed mine pressure data and the numerical simulation method to determine the degree and distance of influence of the fully mechanized mining work on the stress of the collapse column, so as to determine the timing of reinforcement of the collapse column; analyze the grouting diffusion radius based on the subsequent drilling cuttings logging and sand sample data, and make the grouting diffusion radius reach the designed diffusion radius; within the scope of collapse column treatment C3 9 Ash to 1 coal bottom plate forms a relatively impermeable layer;

[0021] S9. After the N1 hole branch and the N2 hole branch pass through the collapse column, a stable working surface is formed by relying on the N1 hole branch and the N2 hole branch to pass through the collapse column.

[0022] The present invention arranges the drilling directions of the N1 hole branch and the N2 hole branch according to the shape and position of the collapse column, and sets the number of holes to perform grouting reinforcement according to the specific size of the collapse column, thereby improving its corresponding mechanical properties and bearing capacity. 9 The ash to coal bottom plate forms a relatively impermeable layer, so that the working face can directly pass through the collapse column.

[0023] Compared with the prior art, the technical solution of this application has the following beneficial effects:

[0024] 1. The double-layer treatment method of the collapse column shown in the present invention is to set one side as the N1 hole branch, which is arranged in parallel along the working surface of the upper rock layer; the other side is set as the N2 hole branch, which is arranged in parallel along the working surface of the lower rock layer; and form C3 according to the specific hole branches. 9 Ash control area, C3 3下 In the ash treatment area and comprehensive treatment area, the filling and reinforcement of the stratum fissures within the collapse column treatment area are good, achieving the design purpose of grouting treatment, and the grouting quality is qualified. The upper and lower exploration and double-layer grouting treatment mode is implemented within the treatment area of ​​the collapse column impact area to increase the accuracy of abnormal stratum exploration and enhance the treatment effect. That is, the upper treatment target layer is selected in C3 3下 Gray layer, the target layer for lower layer treatment is selected at C3 9 The ash corresponds to the depth layer; the upper and lower trajectories are arranged at a large angle, and the overlapping area of ​​the two target layers is the effective treatment plane range of the collapse column, and the design treatment range is fully covered without blind spots, exceeding the design requirements. The cumulative amount of cement injected for treatment is 2.02 times that of single-layer grouting treatment. Cement debris was found in the drilling cuttings in the later construction, and the amount of drilling grouting decreased significantly. The filling and reinforcement of the stratum fissures within the collapse column treatment area was better, achieving the design purpose of grouting treatment.

[0025] 2. The double-layered method for the treatment of collapse columns presented in the present invention can provide safety protection for coal mining through the intensified exploration and treatment of karst collapse columns, while also liberating more coal resources and bringing greater economic benefits.

[0026] 3. The double-layer treatment method of the collapsed column demonstrated in the present invention is to set one side as the N1 hole branch, which is arranged parallel to the working surface of the upper rock layer; the other side is set as the N2 hole branch, which is arranged parallel to the working surface of the lower rock layer; so that the drilling efficiency is high and the deviation of the drilling due to different rock layers is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 A schematic diagram of an embodiment of a double-layer treatment method for a collapsed column according to the present invention;

[0029] Figure 2 It is a schematic diagram of the treatment range of the collapse column influence zone of an embodiment of a double-layer treatment method of a collapse column in the present invention.

[0030] In the figure: 1. N1 hole branch; 2. N2 hole branch; 3. C3 9 Ash control area; 4, C3 3下 Gray control area; 5. Comprehensive control area. DETAILED DESCRIPTION

[0031] First of all, it should be pointed out that in the different described embodiments, the same parts are provided with the same reference numerals or the same component names, wherein the disclosure contained in the entire description can be transferred to the same parts with the same reference numerals or the same component names. Selected positional descriptions in the description, such as top, bottom, lateral, etc., also refer to the directly described and shown figures and are transferred to the new positions in the case of a change in position.

[0032] Embodiment 1:

[0033] See also Figure 1 - Figure 2 , the present invention provides a technical solution:

[0034] A double-layer treatment method for a collapsed column comprises the following steps:

[0035] S1. Determine the rock physical and mechanical parameters in the coal roof, floor and rock formations through geophysical exploration or drilling;

[0036] S2. Determine the boundary of the collapse column and the water content in the collapse column through geophysical exploration or drilling, and drain the water;

[0037] The plane shape of the collapse column is approximately elliptical, with the major axis running in the NE direction, and the spatial shape is a cone that is "small on top and large on the bottom";

[0038] According to the exploration results of 1-1, 1-2 and 1-3 in the collapsed column, it is shown that:

[0039] The collapse column is a highly water-conductive collapse column, with the characteristics of strong vertical water conductivity and weak horizontal permeability. The collapse zone and the influence zone are both highly water-conductive. The influence zone is weakly water-rich in the Permian coal-bearing strata, weakly to extremely water-rich in the Taihui and below strata, and the collapse zone is strong to extremely water-rich. Therefore, the hydrogeological conditions of the collapse column are complex.

[0040] S3. Sampling and analysis: drilling and sampling of the collapse column rock, logging of rock cuttings and sand sampling, and determination of the natural uniaxial compressive strength, porosity, water content and permeability coefficient of the samples;

[0041] From the results of the sampling and analysis of the bottom plate of the coal roof, the compressive strength of rocks of the same lithology is slightly smaller, indicating that they are affected by the collapse column. At the same time, the rock mass in the collapse zone and the affected zone of the collapse column is highly fragmented, especially in the collapse zone. Through the pumping test, it is known that the affected zone and the collapse zone of the collapse column are extremely water-rich and highly conductive.

[0042] S4, partition and predict the physical and mechanical parameters of each zone after reinforcement: that is, determine the partition according to the oblique side structure of the two sides of the collapse column and the rock structure: one side is set as N1 hole branch 1, arranged parallel to the working surface of the upper rock layer; the other side is set as N2 hole branch 2, arranged parallel to the working surface of the lower rock layer; and form C3 according to the specific hole branch 9 Ash control area 3, C3 3下 Ash treatment area 4 and comprehensive treatment area 5; according to the shape and position of the collapse column, the entire directional layer segment trajectory of the N1 hole branch 1 is in C3 9 Gray or C3 9 Construction in the sandstone layer above the gray, all directional along-layer sections of N2 hole branch 2 are located in C3 3下 During the construction of the ash layer, all drilling groups strictly control the layer position, and the layer (depth) rate shall not be less than 80%; the actual trajectory of the branch hole shall not deviate from the designed trajectory by more than 2m, and the hole section greater than 2m shall not exceed 15% of the entire hole section. The number of drilling holes shall be set according to the specific size of the collapse column for grouting reinforcement to improve its corresponding mechanical properties and bearing capacity.

[0043] S5. Simulated grouting test: Based on the physical and mechanical parameters of the consolidation bodies in the three areas obtained in S4, simulated grouting tests are carried out on the collapsed column samples with slurries of different types and proportions to determine the type and proportion of the slurry.

[0044] Confirm the grouting principle and grouting stopping method: follow the principle of first thin and then thick, and re-inject thick slurry, stop slurry at the hole, and use the forward grouting method. Combine continuous grouting with intermittent grouting, and the intermittent grouting time should not be less than 12 hours.

[0045] Slurry specific gravity and proportion, slurry specific gravity 1.2 ~ 1.5. Water-cement ratio 3.0:1, specific gravity 1.20; water-cement ratio 2.0:1, specific gravity 1.29; water-cement ratio 1.4:1, specific gravity 1.39; water-cement ratio 1.0:1, specific gravity 1.51.

[0046] The grouting material generally uses 32.5 slag silicate cement; medium and fine sand is selected as the aggregate.

[0047] S6. Determine the spacing of the grouting holes in the top plate reinforcement area based on the porosity and permeability of the collapse column measured in S3, and then determine the setting time and grouting pressure, and select the grouting machine.

[0048] S7, N1 hole branch 1 and N2 hole branch 2 are grouting synchronously: first, the corresponding C3 of the collapse column is grouting 9 Ash Control Zone 3 and C3 3下 The ash treatment zone 4 is injected with the corresponding slurry determined by injection S5;

[0049] The N1 hole branch 1 and the N2 hole branch 2 are grouting simultaneously by drilling and grouting;

[0050] S8. Use the observed mine pressure data and the numerical simulation method to determine the degree and distance of influence of the fully mechanized mining work on the stress of the collapse column, so as to determine the timing of reinforcement of the collapse column; analyze the grouting diffusion radius based on the subsequent drilling cuttings logging and sand sample data, and make the grouting diffusion radius reach the designed diffusion radius; according to the grouting situation analysis, C3 3 下 Gray and C3 9 The main vertical cracks between the ashes have been filled with slurry.

[0051] Within the scope of collapse column treatment C3 9 The ash to 1 coal bottom plate are relatively impermeable layers, and the 1 coal bottom plate is far from C3 9 The ash spacing is 69.59-81.18m, with an average of 75.55m. The effective vertical thickness of treatment is 75.55m;

[0052] S9. After the N1 hole branch 1 and the N2 hole branch 2 pass through the collapse column, a stable working surface is formed by relying on the N1 hole branch 1 and the N2 hole branch 2 to pass through the collapse column.

[0053] When the working face passes through the collapse column, within the collapse column treatment range C3 9 The ash to coal bottom plate forms a relatively impermeable layer, so that the working face can directly pass through the collapse column.

[0054] According to the analysis of drilling cuttings logging and other data, the grouting diffusion radius has mostly exceeded 40m, reaching the designed diffusion radius (30m). According to the designed theoretical diffusion radius of 30m, the effective treatment area is calculated. The target layer of N1 group treatment is the lower C3 9 Gray or C3 9 Gray roof sandstone, actual treatment area is 222650m 2 The target layer of N2 hole treatment is the upper C3 3下 The actual treatment area is 153894m 2 The overlapping area of ​​the two target layers is the effective treatment plane range of the collapse column, and the actual treatment area is 107591m 2 , which is 1.44 times the designed management area, and achieves full coverage of the designed management range without blind spots, exceeding the design requirements.

[0055] The final technical effect achieved is:

[0056] (1) A total of 179,424.13 tons of cement was injected during this treatment, which is 2.02 times the designed injection volume (89,000 tons).

[0057] (2) The final grouting pressure of each branch hole is not less than 1.5 times the hydrostatic pressure of the Ordovician ash, and the maximum reaches 1.75 times (N1-1 branch hole). The initial grouting pressure is 0-8.9MPa, and the final grouting pressure is 7.7-11MPa. The pump volume at the end of grouting is controlled at 60L / min. The unit water absorption rate of each branch hole after grouting is between 0.0009 and 0.0016L / (min·m·m), which is much lower than the design requirement of 0.01L / (min·m·m). All branch holes meet the designed grouting end standard.

[0058] (3) No grouting occurred during grouting, indicating that C3 3下 Gray and C3 9 The vertical cracks between the ashes have been filled with slurry, blocking the hydraulic connection between the upper and lower layers.

[0059] (4) The grouting volume and unit grouting volume of the grouting holes constructed in the later stage were significantly less than those of the grouting holes constructed in the earlier stage, indicating that the early grouting filled most of the stratum cracks in the treatment area.

[0060] (5) In the later stage of grouting, a large number of solidified cement blocks can be seen in the rock cuttings returned from the drilling, the grouting amount of the drilling hole has decreased significantly, and the whole hole is in a gushing state, indicating that the slurry diffusion radius reaches and exceeds the hole spacing, and the slurry diffusion range effectively covers the treatment area.

[0061] (6) Through-hole re-injection was carried out on branch 1 of N1 hole and branch 2 of N2 hole, which also served as verification holes. The unit water absorption rate of water pressure before injection was significantly reduced compared with the previous period, indicating that the permeability of the formation in this area was poor after grouting treatment, the formation cracks had been well filled, and the grouting treatment effect was good.

[0062] In summary, the filling and reinforcement of the stratum fissures within the scope of the collapse column treatment area are good, achieving the design purpose of grouting treatment, and the grouting quality is qualified. The mode of upper and lower exploration and double-layer grouting treatment is implemented within the scope of the collapse column impact area treatment, and the cumulative amount of cement injected for treatment is 2.02 times the designed grouting amount (89,000 tons). Cement debris was found in the drilling cuttings in the later construction, and the amount of grouting absorbed by the drilling was significantly reduced. The filling and reinforcement of the stratum fissures within the scope of the collapse column treatment area are good, achieving the design purpose of grouting treatment.

[0063] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A double-layer treatment method for a collapsed column, characterized in that: The following steps are involved: S1. Determine the rock physical and mechanical parameters in the coal roof, floor and rock formations through geophysical exploration or drilling; S2. Determine the boundary of the collapse column and the water content in the collapse column through geophysical exploration or drilling, and drain the water; S3. Sampling and analysis: drilling and sampling of the collapse column rock, logging of rock cuttings and sand sampling, and determination of the natural uniaxial compressive strength, porosity, water content and permeability coefficient of the samples; S4, partition and predict the physical and mechanical parameters of each area after reinforcement: that is, determine the partition according to the oblique side structure of the two sides of the collapse column and the rock layer structure: one side is set as the N1 hole branch (1); the other side is set as the N2 hole branch (2); and C3 is formed according to the specific hole branch 9 Ash treatment area (3), C3 3下 ash control area (4) and comprehensive control area (5); S5, simulated grouting test: according to the physical and mechanical parameters of the consolidation bodies in the three regions obtained in S4, simulated grouting tests are conducted on the collapsed column samples with slurries of different types and proportions to determine the type and proportion of the slurry; S6. Determine the spacing of the grouting holes in the top plate reinforcement area according to the porosity and permeability of the collapse column measured in S3, and then determine the setting time and grouting pressure, and select the grouting machine; S7, N1 hole branch (1) and N2 hole branch (2) are grouting simultaneously: first, the corresponding C3 of the collapse column is grouting. 9 Ash control area (3) and C3 3下 The ash treatment area (4) is injected with the corresponding slurry determined by injection S5; S8. Use the observed mine pressure data and the numerical simulation method to determine the degree and distance of influence of the fully mechanized mining work on the stress of the collapse column, so as to determine the timing of reinforcement of the collapse column; analyze the grouting diffusion radius based on the subsequent drilling cuttings logging and sand sample data, and make the grouting diffusion radius reach the designed diffusion radius; within the scope of collapse column treatment C3 9 Ash to 1 coal bottom plate forms a relatively impermeable layer; S9. After the N1 hole branch (1) and the N2 hole branch (2) pass through the collapse column, a stable working surface is formed by relying on the N1 hole branch (1) and the N2 hole branch (2) to pass through the collapse column.

2. A double-layer treatment method for a collapsed column according to claim 1, characterized in that: The N1 hole branch (1) is arranged to be parallel to the working surface of the upper rock layer; and the N2 hole branch (2) is arranged to be parallel to the working surface of the lower rock layer.

3. A double-layer treatment method for a collapsed column according to claim 1, characterized in that: The N1 hole branch (1) and the N2 hole branch (2) are grouted simultaneously by drilling and grouting.

4. A double-layer treatment method for a collapsed column according to claim 1, characterized in that: In step S5, the grouting principle follows the method of first injecting thin slurry and then thick slurry, and then injecting thick slurry again.

5. A double-layer treatment method for a collapsed column according to claim 4, characterized in that: In step S5, the grouting stopping method adopts a combination of continuous grouting and intermittent grouting, and the intermittent grouting time is not less than 12 hours.

6. A double-layer treatment method for collapsed columns according to claim 5, characterized in that: In step S5, the grouting material generally uses 32.5 slag silicate cement; medium and fine sand is selected as the aggregate to be added.

Images