Drill hole drainage depressurization enhanced grouting method for confined aquifer

Abstract

The invention belongs to the technical field of geological engineering, and particularly relates to a confined aquifer drilling drainage depressurization enhanced grouting method which comprises the steps that the grouting transformation range is determined; a grouting drill hole and a pressure reducing hole are constructed, and the slurry diffusion radius of the grouting drill hole is determined through the pressure reducing hole; determining the positions of other pressure reducing holes according to the slurry diffusion radius; grouting is started to be conducted in the grouting drill hole; after grouting is completed, the pressure reducing holes are treated; and repeating the processes until the transformation is finished. The grouting hole is formed in the center of the grouting transformation area, and the pressure reducing holes are formed in the periphery of the grouting hole, so that the water pressure of the aquifer is effectively reduced, the diffusion range of grout is remarkably expanded, and the grout is promoted to more uniformly permeate and fill cracks of the aquifer. The grouting efficiency is improved, material consumption is remarkably reduced, and the grouting method has high economic benefits and is particularly suitable for mine water prevention and control engineering under complex geological conditions. The grouting effect is greatly improved, and the technical scheme is efficient and economical.

Description

Technical Field

[0001] The invention belongs to the technical field of geological engineering, and in particular relates to a method for drilling drainage, depressurizing and enhancing grouting in a pressurized aquifer. Background Art

[0002] As mine mining shifts from upper coal groups to lower coal groups, from shallow to deep, and from non-pressurized areas to pressurized areas, hydrogeological conditions change from simple to complex, and the risk of coal mining on pressurized water bodies gradually increases, seriously restricting the safe and efficient production of mines in the new era.

[0003] In particular, highly pressurized aquifers have always been the focus and difficulty in the field of mine water prevention and control because of their highly developed fractures, extremely strong and uneven water richness, and high water pressure.

[0004] At present, the more mature technology for the management of pressurized water in aquifers is to use a ground grouting station to carry out grouting transformation on the aquifer through grouting pipelines and grouting boreholes on the underground working face, fill the water-conducting structure, cut off the water supply channel, and transform the aquifer into a weak aquifer or a water-free layer, increase the thickness of the coal seam floor waterproof layer, and realize water-free mining at the coal working face.

[0005] However, it is difficult to ensure the grouting transformation effect when using this method of grouting. One of the reasons is that the high water pressure conditions in the aquifer inhibit the diffusion of the slurry, which can easily lead to grouting difficulties and difficulty in the slurry to fully enter the water-bearing fissures in the aquifer, thus forming a grouting blind spot and leaving a hidden danger of water leakage.

[0006] Therefore, it is necessary to design a method for depressurizing and enhancing grouting in confined aquifers through drilling and drainage to solve the above problems. Summary of the invention

[0007] The purpose of the invention is to provide a method for enhancing grouting in a pressure-bearing aquifer by drilling drainage and depressurization, so as to solve the problem that slurry is difficult to enter and insufficiently diffuses when grouting to transform the aquifer.

[0008] To achieve the above object, the present invention provides the following scheme: a method for enhancing grouting by drilling drainage and depressurization in a confined aquifer, comprising:

[0009] Determine the scope of grouting transformation;

[0010] Construct a grouting borehole and a pressure relief hole, and determine the slurry diffusion radius of the grouting borehole through the pressure relief hole;

[0011] Determine the positions of other pressure-reducing holes according to the slurry diffusion radius;

[0012] Start grouting into the grouting borehole;

[0013] After grouting is completed, the pressure reduction holes are processed;

[0014] Repeat the above process until the transformation is completed.

[0015] Based on the method for enhancing grouting by drilling drainage and reducing pressure in a confined aquifer of the present invention, the scope of grouting transformation is determined according to the needs of coal mining.

[0016] According to the method for enhancing grouting for drainage and pressure reduction in a confined aquifer according to the present invention, when determining the positions of other pressure reduction holes, an inscribed hexagon is made within the circular range of slurry diffusion, and adjacent inscribed hexagons are made with one side of the inscribed hexagon. The distance between the center points of the two inscribed hexagons is the spacing between the grouting borehole and the other pressure reduction holes.

[0017] According to the method for enhancing grouting by drilling drainage and reducing pressure in a confined aquifer of the present invention, the grouting borehole and any two adjacent reducing pressure holes form an equilateral triangle.

[0018] According to the method for enhancing grouting by drilling drainage and reducing pressure in a confined aquifer of the present invention, when grouting is injected into the grouting borehole, parameters in the grouting borehole are monitored.

[0019] According to the method for enhancing grouting by drilling drainage and reducing pressure in a confined aquifer of the present invention, the monitored parameters include water flow and slurry concentration.

[0020] Based on the method for enhancing grouting by drilling drainage and reducing pressure in a confined aquifer of the present invention, after the grouting is completed, the area that needs to be grouted in the next step is planned, if the position of the pressure reduction hole that has been constructed is located around the area that needs to be grouted in the next step, and it can be ensured that there is no grouting blind area and the water pressure of the aquifer is effectively reduced, it will be used as the pressure reduction hole in the next grouting transformation area; if the position of the pressure reduction hole that has been constructed is located at the center of the next grouting transformation area, it will be transformed into a grouting drill hole, otherwise, the pressure reduction hole will be blocked.

[0021] According to the method for enhanced grouting in a confined aquifer through drilling, drainage and pressure reduction, the present invention provides a slurry diffusion radius which is an enhanced grouting diffusion radius.

[0022] Compared with the prior art, the present invention has the following advantages and technical effects:

[0023] 1. The present invention constructs a borehole into the aquifer through the determined grouting transformation and slurry diffusion range, arranges a grouting borehole in the center of the grouting transformation area, and arranges a plurality of pressure reduction holes around the grouting borehole to further increase the slurry diffusion range and ensure that the formed pressure reduction area is larger than the pre-grouting transformation range.

[0024] 2. The present invention can avoid the existence of grouting blind spots in the grouting transformation area, and on this basis, save grouting materials to the maximum extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor:

[0026] Figure 1 It is a schematic diagram of the method of the present invention;

[0027] Figure 2 A schematic diagram of a single pressure reduction hole and a grouting drilling hole of the present invention;

[0028] Figure 3 It is a schematic diagram of multiple pressure reduction holes and grouting drilling holes of the present invention;

[0029] Figure 4 This is a schematic diagram illustrating the principle of arrangement of a single pressure-reducing hole of the present invention;

[0030] Figure 5 This is a schematic diagram of the grouting repetition area;

[0031] Figure 6 It is the relationship diagram between the grouting repetition area and the drilling arrangement;

[0032] Figure 7 This is a graph showing the relationship between the area of ​​the grouting repetition zone and the angle function.

[0033] Among them, 1. grouting borehole; 2. pressure reduction hole; 3. inscribed hexagon; 4. aquifer; 5. coal seam; 6. conventional grouting diffusion radius; 7. enhanced grouting diffusion radius; 8. repeated grouting area. DETAILED DESCRIPTION

[0034] 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.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Reference Figures 1 to 7 As shown, the present invention provides a method for drilling drainage, depressurizing and enhancing grouting in a confined aquifer, comprising:

[0037] Determine the scope of grouting transformation;

[0038] A grouting borehole 1 and a pressure-reducing hole 2 are constructed, and the slurry diffusion radius of the grouting borehole 1 is determined through the pressure-reducing hole 2;

[0039] Determine the positions of other pressure-reducing holes 2 according to the slurry diffusion radius;

[0040] Start grouting into the grouting borehole 1;

[0041] After grouting is completed, the pressure relief hole 2 is processed;

[0042] Repeat the above process until the transformation is completed.

[0043] The water pressure of the aquifer 4 is reduced by draining water through the pressure-reducing hole 2, thereby achieving the purpose of enhancing the grouting effect.

[0044] Furthermore, when determining the scope of grouting transformation, it is determined based on the needs of coal mining.

[0045] Furthermore, when determining the positions of other pressure reducing holes 2, an inscribed hexagon 3 is made within the circular range of slurry diffusion, and an adjacent inscribed hexagon 3 is made with one side of the inscribed hexagon 3. The distance between the center points of the two inscribed hexagons 3 is the spacing between the grouting borehole 1 and the other pressure reducing holes 2.

[0046] Furthermore, the grouting borehole 1 and any two adjacent pressure reduction holes 2 form an equilateral triangle.

[0047] Furthermore, when grouting is performed into the grouting borehole 1 , the parameters in the grouting borehole 1 are monitored.

[0048] During the grouting process, the changes in water pressure, water level and water flow rate in the pressure reducing hole 2 are continuously monitored to ensure that the slurry can diffuse more efficiently.

[0049] Furthermore, the monitored parameters include water flow and slurry concentration.

[0050] Furthermore, after the grouting is completed, the area that needs to be grouted in the next step is planned. If the position of the constructed pressure reduction hole 2 is located around the area that needs to be grouted in the next step, and it can ensure that there is no grouting blind area and the water pressure of the aquifer 4 is effectively reduced, it will be used as the pressure reduction hole 2 in the next grouting modification area; if the position of the constructed pressure reduction hole 2 is located at the center of the next grouting modification area, it will be converted into a grouting borehole 1, otherwise, the pressure reduction hole 2 will be blocked.

[0051] Furthermore, the slurry diffusion radius is the enhanced grouting diffusion radius 7.

[0052] Determine the diameter, depth and angle of the grouting borehole 1 and the pressure-reducing hole 2. The parameters of the grouting borehole 1 determine the unit time flow rate, pressure of the grouting injection and the injection position of the grouting to a certain extent, and the parameters of the pressure-reducing hole 2 determine the speed and size of the pressure reduction. The determination and matching of the above parameters need to be designed according to the pre-grouting transformation range and the slurry diffusion capacity. Under the premise of ensuring the accuracy of the slurry injection position, determine the parameters of the pressure-reducing hole 2.

[0053] The pressure reduction hole 2 can reduce the water pressure of the aquifer by draining water, forming a pressure reduction zone between the grouting borehole 1 and the pressure reduction hole 2. The grouting borehole 1 has a certain grouting pressure under the action of the grouting equipment. This grouting pressure will further increase the pressure gradient between the two types of boreholes, forming an active injection technology of "both pressure and attraction". Therefore, the grouting borehole 1 should be guaranteed to cover the target transformation area, and the pressure reduction hole 2 should be set around the grouting borehole 1 to form an effective water pressure reduction system between the grouting borehole 1 and the pressure reduction hole 2.

[0054] Use drilling equipment to carry out drilling construction, complete drilling according to design requirements, ensure that the position and number of grouting boreholes 1 and pressure reduction holes 2 meet the design requirements, and ensure that the verticality and depth of the boreholes meet the requirements. Select the type of drilling rig according to the engineering geological conditions of the construction site. During the construction process, the type of drill bit can also be selected according to the situation. Each drilling rig is equipped with two drill bits, one of which is on standby. When the drilling rig is running, adjust the drill bit stroke appropriately according to geological changes and drilling speed, frequently perform cone head repair welding, check the hole diameter and borehole inclination at any time, keep drilling records and handover records, and ensure that the diameter, depth and angle of the grouting borehole 1 and the pressure reduction hole 2 meet the expected requirements.

[0055] The grouting operation is carried out through the grouting borehole 1. Before grouting, pressurized water is first injected into the grouting borehole 1 to displace the sediment and silt, and the grouting pipe is cleaned and unblocked, and then the sediment in the grouting pipe is displaced with thin slurry. The grouting pressure is different at different stages of grouting. The slurry concentration must be properly adjusted with the change of grouting pressure, generally thin slurry first and thick slurry last. Thin slurry is easy to transport and has strong permeability. Medium-concentration slurry plays a filling and compacting role, and thick slurry has a dehydrating effect on the injected slurry. The pressure of the pressure gauge must be closely observed during grouting. When the grouting pressure suddenly drops and the flow rate suddenly increases, the grouting must be stopped immediately for inspection. When slurry bubbling or slurry running occurs, the grouting must be stopped immediately. At the same time, during the slurry injection process, the changes in water pressure, water level and water flow rate in the pressure reducing hole 2 should be continuously monitored and controlled through the pressure reducing hole 2, and the osmotic pressure difference of the strong aquifer between the grouting borehole 1 and the pressure reducing hole 2 should be adjusted in real time according to the diffusion of different slurries, forming an active injection technology of "both pressure and induction" to ensure that the slurry can be effectively injected and evenly and efficiently diffused.

[0056] The solution demonstration process of the present invention:

[0057] In order to reduce costs, while ensuring full grouting of the entire area, the grouting materials are fully utilized. Therefore, it is necessary to establish a mathematical model of the grouting volume and the drilling hole arrangement position. However, for different geological conditions, the grouting volume often varies greatly. Therefore, the present invention makes the following assumptions:

[0058] Assume that the density of the slurry is the same everywhere in the diffusion circle.

[0059] Therefore, under ideal conditions, the area of ​​the diffusion circle can be used to equivalently replace the grouting volume. At this time, a mathematical model of the diffusion circle area and drilling arrangement can be established.

[0060] The waste of grouting materials is mainly reflected in the loss of grout and repeated grouting in the grouting area. Under the condition of ignoring the mutual influence between grouts, it is mainly concentrated in the repeated areas between the diffusion circles, see Figure 5 .

[0061] At this point, just consider Figure 6 The relationship between the shadow area S and the angle α can be used to prove that a specific α minimizes the shadow area. Based on the above requirements, we can establish Figure 6 Using the analytic geometry and coordinate system shown in , find the functional relationship between the shaded area S and the angle α.

[0062] Since the radius of the diffusion circle R is a known fixed value, and the spacing D of the first row of holes is designed based on R, the spacing D is also known. For the convenience of later calculations, assume that R is 1m. The main discussion is about the functional relationship between the area S of the shadow part and the angle α. This value does not affect the changing law of the two.

[0063] Therefore, the problem is simplified into solving Figure 6 The relationship between the area of ​​the shaded part and the angle α. Assume that the center of the unknown circle is (a, b), then the coordinates of the center satisfy:

[0064]

[0065] The shaded area in the figure is:

[0066] S=S5+S6+S7 (2)

[0067] Among them: S is the area of ​​the shaded part; S5 is the area of ​​the shaded part on the left; S6 is the area of ​​the shaded part on the right; S7 is the area of ​​the shaded part in the middle.

[0068] Since the two circles on the x-axis are fixed, S7 is also a constant, and we only need to discuss the sum of S5 and S6. Therefore, we set S7 = 0 to simplify the calculation.

[0069] The shaded area on the left is:

[0070] S5=2S1-S3 (3)

[0071] Among them, S1 is the area of ​​the left sector; S3 is the area of ​​the left quadrilateral.

[0072] The shaded area on the right is:

[0073] S6=2S2-S4 (4)

[0074] Among them, S2 is the area of ​​the sector on the right; S4 is the area of ​​the quadrilateral on the right.

[0075] According to the area calculation formula of the sector, the areas of the two sectors are obtained:

[0076]

[0077] Areas of two quadrilaterals:

[0078]

[0079] Combining formulas (1)-(8), we can obtain the relationship between area S and angle α:

[0080]

[0081] Use Matlab to plot the changing trend of area S and angle α. Figure 7 As shown. When α=π / 3=1.046, S takes the minimum value, and the shadow area is the smallest. Therefore, it can be proved that when the angle between α and the horizontal is set to 60°, the repeated grouting area is the smallest, and the grouting material is saved the most at this time, so as to achieve the purpose of improving economic benefits.

[0082] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0083] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the protection scope of the present invention.

Claims

1. A method for enhancing grouting by drilling drainage and depressurization in a confined aquifer, characterized in that: include Determine the scope of grouting transformation; Constructing a grouting borehole (1) and a pressure reducing hole (2), and determining the slurry diffusion radius of the grouting borehole (1) through the pressure reducing hole (2); Determine the positions of other pressure-reducing holes (2) according to the slurry diffusion radius; Starting to inject grout into the grouting borehole (1); After the grouting is completed, the pressure relief hole (2) is processed; Repeat the above process until the transformation is completed.

2. A method for enhancing grouting by drilling and drainage of a confined aquifer according to claim 1, characterized in that: When determining the scope of grouting transformation, it should be determined based on the needs of coal mining.

3. A method for enhancing grouting by drilling drainage and depressurization of a confined aquifer according to claim 1, characterized in that: When determining the positions of other pressure reducing holes (2), an inscribed hexagon (3) is made within the circular range of slurry diffusion, and adjacent inscribed hexagons (3) are made with one side of the inscribed hexagon (3), and the distance between the center points of the two inscribed hexagons (3) is the spacing between the grouting borehole (1) and the other pressure reducing holes (2).

4. A method for enhancing grouting by drilling drainage and depressurization of a confined aquifer according to claim 1, characterized in that: The grouting borehole (1) and any two adjacent pressure reduction holes (2) form an equilateral triangle.

5. The method for reducing pressure and enhancing grouting in a confined aquifer according to claim 1, characterized in that: When grouting is injected into the grouting borehole (1), the parameters in the grouting borehole (1) are monitored.

6. A method for enhancing grouting by drilling drainage and depressurization of a confined aquifer according to claim 5, characterized in that: The parameters monitored include water flow and slurry concentration.

7. A method for enhancing grouting by drilling drainage and depressurization of a confined aquifer according to claim 1, characterized in that: After the grouting is completed, the area that needs to be grouted in the next step is planned. If the location of the pressure reducing hole (2) that has been constructed is located around the area that needs to be grouted in the next step, and it can ensure that there is no grouting blind area and the water pressure of the aquifer (4) is effectively reduced, it will be used as the pressure reducing hole (2) in the next grouting modification area; if the location of the pressure reducing hole (2) that has been constructed is located at the center of the next grouting modification area, it will be transformed into a grouting drill hole (1), otherwise, the pressure reducing hole (2) will be blocked.

8. The method for depressurizing and enhancing grouting in a confined aquifer according to claim 1, characterized in that: The slurry diffusion radius is the enhanced grouting diffusion radius (7).

Images