A method for reinforcing overburden separation layer of goaf of deformation-sensitive structure

Abstract

The application discloses a kind of overburden separation zone reinforcement method of deformation sensitive structure goaf, including determining the boundary size and vertical height of overburden separation zone of goaf;Determine the boundary of blasting treatment of overburden separation zone of goaf;Design the amount of directional blasting explosive and the distance between explosive and the top of overburden separation zone, so that the rock and soil around explosive on the boundary of deformation sensitive structure foundation influence boundary is formed by directional blasting Throw pile;After the hole of hole drilling along the original blasthole distribution boundary to the original overburden separation zone bottom elevation and inject water reaction foaming polyurethane to form flow-plastic viscous liquid, flow-plastic viscous liquid rapidly diffuses along the upper and lower boundary of overburden separation zone and the interstice between original broken overburden separation zone accumulation block and forms blocking boundary;Deep grouting method is used to reinforce the cavity in blocking area.This method aims to reduce the disturbance of blasting on the upper soil layer and deformation sensitive structure, reduce the consumption of slurry, save engineering cost, and improve the treatment effect of goaf site.

Description

Technical Field

[0001] This invention relates to the field of blasting collapse and grouting reinforcement technology, specifically to a method for reinforcing the overlying delamination in the goaf of deformation-sensitive structures. Background Technology

[0002] my country has a huge amount of underground resources. After these resources are mined out, a large number of goaf areas will be formed. The old roof of the goaf area will gradually collapse, forming an overlying delamination layer. The appearance of the overlying delamination layer will cause the soil layer to slowly deform and reconsolidate, disturbing the stress distribution of the original soil layer, affecting the stability of the foundation, and threatening the safety of surface workers or deformation-sensitive structures. Therefore, it is necessary to reinforce the overlying delamination layer of the goaf area.

[0003] In existing technologies, reinforcement methods for goaf areas are generally divided into blasting and grouting. Blasting involves determining the amount of explosives and the location of blast holes based on engineering experience, and then blasting the goaf as a whole to compact and stabilize the overlying strata. Grouting involves injecting certain solidifiable grouts into cracks or pores in the rock and soil foundation to improve the physical and mechanical properties of the overlying strata. Since the soil layer above the goaf has already consolidated and is basically stable, blasting the goaf as a whole is relatively expensive and can disturb the soil layer above it, affecting deformation-sensitive structures. Direct grouting, due to the complex distribution and large penetration area of ​​the overlying strata, can cause grout to leak along the strata, resulting in waste and significantly increasing project costs. Summary of the Invention

[0004] To address the aforementioned technical shortcomings, the purpose of this invention is to provide a method for reinforcing the overlying delamination in goaf areas of deformation-sensitive structures. This method aims to reduce the disturbance of blasting to the overlying soil layers and deformation-sensitive structures, while ensuring that the grout does not flow away with the goaf, thereby reducing grout consumption, saving engineering costs, and improving the treatment effect of the goaf site.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] This invention provides a method for reinforcing the overlying delamination in the goaf of deformation-sensitive structures.

[0007] S1: Collect data on the distribution of goaf areas and hydrogeological exploration data of sites to be reinforced, obtain the stratigraphic state of sites to be reinforced, and determine the distribution of overlying strata in goaf areas.

[0008] S2: Design blasting for the overlying delamination of the goaf on the boundary of the foundation of deformation-sensitive structures, so that the overlying delamination of the goaf on the boundary of the foundation of deformation-sensitive structures collapses by blasting, ensuring that the subsequent injection of sealing materials will not be lost.

[0009] S3: After the directional blasting is completed, a secondary hole cleaning is performed, and water is injected along the blast hole to react and foam polyurethane to form a sealing boundary;

[0010] S4: Perform grouting reinforcement on the reinforced site and test the grouting results.

[0011] By designing blasting for the goaf, the overlying layer on the boundary of the foundation of deformation-sensitive structures collapses through blasting. After drilling around the blast holes and injecting water to form a sealing boundary for the reaction foamed polyurethane, the goaf site is reinforced by grouting, which greatly reduces the consumption of grout and saves the estimated cost of the project.

[0012] Preferably, in step S1, geological exploration data of the goaf are collected to understand the distribution of overlying delamination in the goaf below the construction site, the boundary size of the overlying delamination and the vertical height between the top and bottom plates of the overlying delamination are determined, and the blasting treatment boundary of the overlying delamination is determined by combining the deformation characteristics of the strata above the goaf and the influence range of the foundation of deformation-sensitive structures.

[0013] Preferably, in step S2, based on the geological data collected in the early stage, the boundary of the overlying strata in the goaf is determined, and directional blasting design is carried out only on the overlying strata in the goaf above the boundary of the foundation of deformation-sensitive structures. This ensures that the overlying strata in the goaf above the boundary of the foundation of deformation-sensitive structures will not completely collapse after directional blasting, thus avoiding changes in the original soil structure above, and that the rocks and soil around the explosives will form a blasting pile under the impact of directional blasting.

[0014] Preferably, in step S2, firstly, borehole design is carried out in the boundary area between the overlying delamination layer and the site influence boundary of the deformation-sensitive structure, and the suspension depth of the explosive, the explosive consumption per unit and the amount of explosive are determined, and finally, directional blasting is carried out on the treatment boundary.

[0015] The distribution of directional blasting holes and the amount of explosives used are designed based on the lithological parameters near the overlying delamination layer. This allows for directional blasting of the overlying delamination layer in the goaf area on the boundary of the foundation of deformation-sensitive structures. The boundary position of the sealing material is determined by the throwing distance of the rock and soil during directional blasting. The amount of sealing material required is calculated based on the boundary size of the goaf area to ensure that the sealing material does not enter the reinforcement area or flow away with the overlying delamination layer.

[0016] Preferably, in step S3, after the blasting collapse is completed, the blasting holes should be cleaned a second time to ensure their unobstructed flow. Then, holes should be drilled along the original blasting hole distribution boundary to the bottom surface of the overlying delamination layer, and water-reacting polyurethane foam should be injected. This allows the polyurethane foam to rapidly diffuse and expand along the upper and lower boundaries of the overlying delamination layer and the interlayer formed by the gravel, forming a sealing boundary. The maximum amount of polyurethane foam required for a single blasting sealing zone is calculated based on the cavity volume formed after directional blasting. The calculation equation is:

[0017] L×H×B+V D =V W

[0018] Where: H and B are the height and width of the overlying delamination layer near the blast hole, respectively, obtained by consulting data on the goaf; L is the width of the directional blasting boulders pile, V D V is the volume between the free face after directional blasting and the original overlying delamination top plate, determined based on the standard explosive consumption and minimum resistance line; W The stable volume of polyurethane foam after it changes upon contact with water;

[0019] The stable volume V of the foamed polyurethane after it changes upon contact with water W The calculation method is as follows:

[0020]

[0021] v1 and v2 represent the expansion and shrinkage rates, respectively; T1 and T2 represent the time required for the polyurethane foam to reach its maximum expansion rate and the time required for its shrinkage recovery rate to reach zero, respectively. These values ​​were determined through indoor testing. i This is the initial amount of polyurethane foam required;

[0022] Therefore, the initial amount V of the foamed polyurethane i for:

[0023]

[0024] The total amount of sealing material required is:

[0025]

[0026] Where V Z N represents the total amount of sealing material required, and N is the number of cavities to be sealed by blasting.

[0027] Preferably, the foamed polyurethane component undergoes a chemical reaction upon mixing at the grouting nozzle, forming a fluid-plastic viscous liquid. Driven by grouting pressure and its own expansion force, it rapidly diffuses along the upper and lower boundaries of the overlying delamination and the pores between the original broken overlying delamination deposits, forming a sealing boundary. After a certain period of time, it shrinks. Therefore, the foamed polyurethane should be injected in multiple portions to avoid problems such as clogging of the blast holes or failure to completely seal the boundary due to excessive injection at one time. The sealing material is only located at the site boundary and will not affect the effect of subsequent grouting reinforcement.

[0028] Preferably, in step S4, grouting reinforcement treatment is carried out on the site, and grouting treatment is carried out on the overlying delamination layer of the goaf in the building site to ensure that the grout can fill the overlying delamination layer in the site to be reinforced and will not flow along the overlying delamination layer, thereby completing the reinforcement treatment of the goaf site.

[0029] The grouting reinforcement of the goaf should be carried out by determining the appropriate grouting process based on the actual engineering conditions and conducting grouting tests. When grouting the goaf, it should be considered whether water seeps into the overlying stratum. If water seeps into the overlying stratum, causing the grout to not solidify completely, sulfoaluminate cement, gypsum, etc. should be injected in advance before grouting to react with water and form an isolation layer before injecting the grout to complete the reinforcement of the overlying stratum of the goaf, ensuring that the grout is located inside the defined overlying stratum.

[0030] The beneficial effects of this invention are as follows: This invention is applicable to the reinforcement method of overlying delamination in the goaf of deformation-sensitive structures. It can perform boundary blasting, sealing and grouting treatment on the underlying goaf of the deformation-sensitive structure site; it only performs directional blasting on the overlying delamination of the goaf on the boundary of the foundation of the deformation-sensitive structure, which reduces the interference of blasting collapse on the soil layer; it uses sealing materials to seal around the reinforcement area, which reduces the amount of grout used during grouting, reduces the project cost, and enables the goaf to achieve a good reinforcement effect. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 A top view of the building and its foundation influence range and the boundary of the goaf area provided in an embodiment of the present invention;

[0033] Figure 2 A borehole distribution diagram provided for an embodiment of the present invention;

[0034] Figure 3 A longitudinal section view of a borehole section provided in an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of grouting provided in an embodiment of the present invention.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1-Site boundary; 2-Boundary of foundation influence area; 3-Boundary of goaf; 4-Blast hole; 5-Upper soil layer; 6-Overlying delamination layer; 7-Hanging rope; 8-Explosive charge; 9-Blast rockfall; 10-Blast cavity; 11-Boundary of goaf sealing; 12-Grouting hole; 13-Grouting slurry. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] See Figure 1 First, mining data and geological exploration data of the goaf are collected, and the distribution of existing goaf areas is investigated. Based on the site boundary 1 of the deformation-sensitive structure, the foundation influence range boundary 2 of the structure is calculated. Based on the distribution of goaf areas, the common area of ​​the goaf boundary 3 and the foundation influence range boundary 2 is determined as the layout area of ​​the blast holes 4.

[0040] See Figure 2 The blasting design of this invention only requires directional blasting to impact and throw rocks at the junction of the overlying strata 6 and the boundary of the building's influence, forming a rock dump at the end of the blast hole, ensuring that the overlying strata will not collapse as a whole, and protecting the soil structure above the overlying strata and the deformation-sensitive structures on the ground; blast holes 4 are arranged at the boundary where the goaf intersects with the influence range 2 of the foundation of the deformation-sensitive structures. During drilling, the height of the overlying strata can be determined by the time it takes for the drill bit to move from the top surface to the bottom of the overlying strata and the speed at which the drill bit moves. Based on the boundary dimensions of the overlying strata, the explosive consumption and charge amount of the blasting explosive 8 are calculated to determine the influence range of the directional blasting impact, ensuring that the overlying strata forms a rock dump with the upper and lower boundaries of the original overlying strata after blasting, thus completing the blasting design of the goaf.

[0041] See Figure 3After determining the height of the overlying delamination layer 6 and the blasting impact range, the explosive 8 is hoisted to the designated height using a hoisting rope 7. The length of the hoisting rope 7 should be determined based on the height of the overlying delamination layer, the depth of the upper soil layer 5, and the height of the explosive. After blasting, the blast hole is cleaned a second time to remove the blasted debris blocking the hole, so that the blasting cavity 10 formed by the blast can be sealed through the blast hole later. The blasted rocks 9 are located around the blast hole, forming the blasting cavity 10 together with the upper and lower boundaries of the original overlying delamination layer. After the second cleaning, polyurethane foam is injected into the blast hole. Experiments show that the polyurethane foam has good waterproof performance. Through on-site spraying, a seamless, integrated waterproof layer can be formed. The polyurethane foam has closed pores with a 95% sealing rate, ensuring that the grout will not leak. Secondly, its rapid spraying speed facilitates faster construction and offers excellent economic benefits. The polyurethane foam components react instantly upon mixing at the grouting nozzle, forming a fluid-plastic viscous liquid. Driven by grouting pressure and its own expansion force, it rapidly diffuses along the upper and lower boundaries of the overlying delamination and the pores between the original broken overlying delamination blocks, forming a sealing boundary. After the polyurethane foam forms a sealing boundary in the pores, grouting reinforcement is designed for the goaf. Adding sealing material ensures that the grout is confined only to filling and reinforcing the area to be treated, and is not wasted by leakage through the pores of the goaf or blasted rocks.

[0042] The maximum amount of polyurethane foam required for a single blast-sealed zone can be calculated based on the cavity volume formed after directional blasting. The calculation equation is as follows:

[0043] L×H×B+V D =V W

[0044] Where: H and B are the height and width of the overlying delamination layer near the blast hole, respectively, obtained by consulting data on the goaf; L is the width of the directional blasting boulders pile, V D V is the volume between the free face after directional blasting and the original overlying delamination top plate, determined based on the standard explosive consumption and minimum resistance line; W The stable volume of polyurethane foam after it changes upon contact with water;

[0045] The stable volume V of the foamed polyurethane after it changes upon contact with water W The calculation method is as follows:

[0046]

[0047] v1 and v2 represent the expansion and shrinkage rates, respectively; T1 and T2 represent the time required for the polyurethane foam to reach its maximum expansion rate and the time required for its shrinkage recovery rate to reach zero, respectively. These values ​​were determined through indoor testing. i This is the initial amount of polyurethane foam required;

[0048] Therefore, the initial amount V of the foamed polyurethanei for:

[0049]

[0050] The total amount of sealing material required is:

[0051]

[0052] Where V Z N represents the total amount of sealing material required, and N is the number of cavities to be sealed by blasting.

[0053] Since polyurethane foam expands first and then shrinks, it should be injected in several stages according to a certain amount to avoid problems such as clogging the blast holes or failing to completely seal the boundary due to excessive injection at one time, and to ensure that it can basically fill the interlayer of the blasted rock-breaking area after the final shrinkage is completed.

[0054] See Figure 4 The sealing boundary 11 of the goaf is located around the blasting holes. Part of this sealing boundary may lie within the foundation's influence zone. Therefore, grouting holes 12 should be installed on both sides of the crushed stone sealing boundary within the foundation's influence zone 2 to ensure complete grouting reinforcement of the goaf within the site. Before grouting, groundwater detection should be conducted on the overlying strata of the grouting area. If seepage water exists in the overlying strata, sulfoaluminate cement, gypsum, etc., should be pre-injected to react with the seepage water before grouting. After forming a seepage water isolation layer, the grout should be injected, and the grouting results should be checked. Finally, the distribution of the grout 13 should be consistent with... Figure 4 Similar to the example shown.

[0055] In this embodiment, the grout injection volume is monitored in real time during the grouting process. If a sudden increase in grout usage occurs, grouting should be stopped immediately to investigate the cause and take timely action. After grouting is completed, monitoring is used to ensure that the grout does not flow out with the goaf. If the results all reflect that the grouting effect in the area is good, it indicates that this scheme is feasible for grouting large goaf areas.

[0056] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for reinforcing the overlying delamination in the goaf of a deformation-sensitive structure, characterized in that: Includes the following steps: S1: Collect data on the distribution of goaf areas and hydrogeological exploration data of sites to be reinforced, obtain the stratigraphic state of sites to be reinforced, and determine the distribution of overlying strata in goaf areas. S2: Design blasting for the overlying delamination of the goaf on the boundary of the foundation of deformation-sensitive structures, so that the overlying delamination of the goaf on the boundary of the foundation of deformation-sensitive structures collapses by blasting, ensuring that the subsequently injected sealing material will not be lost. S3: After the directional blasting is completed, a secondary hole cleaning is performed. Water is injected along the blast hole to react and foam polyurethane to form a sealing boundary, ensuring the sealing of subsequent grouting reinforcement slurry. S4: Perform grouting reinforcement on the reinforced site and test the grouting results; In step S1, geological exploration data of the goaf are collected to understand the distribution of overlying delamination in the goaf below the construction site, determine the boundary size of the overlying delamination and the vertical height between the top and bottom plates of the overlying delamination, and determine the blasting treatment boundary of the overlying delamination by combining the deformation characteristics of the strata above the goaf and the influence range of the foundation of deformation-sensitive structures. In step S2, based on the geological data collected in the early stage, the boundary of the overlying delamination layer of the goaf is determined. Directional blasting design is carried out only on the overlying delamination layer of the goaf above the influence boundary of the foundation of deformation-sensitive structures. This ensures that the overlying delamination layer of the goaf above the influence boundary of the foundation of deformation-sensitive structures will not completely collapse after directional blasting, thus avoiding changes in the original soil structure above. It also allows the rocks and soil around the explosives to form a blasting pile under the impact of directional blasting. First, borehole design is carried out in the boundary area between the overlying delamination and the foundation of the deformation-sensitive structure, and the suspension depth of the explosive, the explosive consumption and the amount of explosive are determined. Finally, directional blasting is carried out on the treatment boundary. In step S3, after the blasting collapse is completed, the blasting holes should be cleaned a second time to ensure their unobstructed flow. Then, boreholes should be drilled along the original blasting hole distribution boundary to the bottom surface of the overlying delamination layer, and water-reactive polyurethane foam should be injected. This foam will rapidly diffuse and expand along the upper and lower boundaries of the overlying delamination layer and the interlayer formed by the gravel, forming a sealing boundary. The maximum amount of polyurethane foam required for a single blasting sealing zone is calculated based on the cavity volume formed after directional blasting. The calculation equation is as follows: L×H×B+V D =V W Where: H and B are the height and width of the overlying delamination layer near the blast hole, respectively, obtained by consulting data on the goaf; L is the width of the directional blasting boulders pile, V D V is the volume between the free face after directional blasting and the original overlying delamination top plate, determined based on the standard explosive consumption and minimum resistance line; W The stable volume of polyurethane foam after it changes upon contact with water; The stable volume V of the foamed polyurethane after it changes upon contact with water W The calculation method is as follows: v1 and v2 represent the expansion and shrinkage rates, respectively; T1 and T2 represent the time required for the polyurethane foam to reach its maximum expansion rate and the time required for its shrinkage recovery rate to reach zero, respectively. These values ​​were determined through indoor testing. i This is the initial amount of polyurethane foam required; Therefore, the initial amount V of the foamed polyurethane i for: The total amount of sealing material required is: Where V Z N represents the total amount of sealing material required, and N is the number of cavities to be sealed by blasting.

2. The method for reinforcing the overlying delamination in the goaf of a deformation-sensitive structure as described in claim 1, characterized in that: After the polyurethane foam components react chemically upon mixing at the grouting nozzle, they form a fluid-plastic viscous liquid. Driven by grouting pressure and its own expansion force, it rapidly diffuses along the upper and lower boundaries of the overlying delamination and the pores between the original broken overlying delamination deposits, forming a sealing boundary. It then shrinks after a certain period of time. When injecting polyurethane foam, it should be injected in multiple portions to avoid clogging the rupture holes or failing to completely seal the boundary due to excessive injection at one time. The sealing material is only located at the site boundary and will not affect the effect of subsequent grouting reinforcement.

3. The method for reinforcing the overlying delamination in the goaf of a deformation-sensitive structure as described in claim 2, characterized in that: In step S4, grouting reinforcement treatment is carried out on the site. Grouting treatment is performed on the overlying delamination layer of the goaf within the building site to ensure that the grout can fill the overlying delamination layer in the site to be reinforced and will not flow along the overlying delamination layer, thus completing the reinforcement treatment of the goaf site.

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