A method and implementation method for dividing and reinforcing underground structures crossing complex strip coal mine goaf based on genetic algorithm

Abstract

The application provides a kind of underground structure crossing complex strip coal mine goaf segmentation reinforcement method based on genetic algorithm, it is related to the field of shield, after how efficient, fast, new solution is proposed to save reinforcement in the known approximate range, trend of goaf, comprising the following steps: step 1: the irregular complex strip coal mine goaf is divided into regular goaf;Step 2: sleeve valve pipe is used to carry out double liquid grouting edge sealing in the regular goaf after segmentation;Step 3: drilling detection verification is carried out in the edge sealing area;Step 4: cement slurry is carried out in the edge sealing area after detection;Step 5: genetic algorithm is used to optimize the selection of grouting equipment point, and the position with the shortest sum of the distance between grouting equipment and grouting hole connection line is taken as the layout position of grouting equipment.

Description

Technical Field

[0001] This invention relates to the field of shield tunnel engineering technology, specifically a method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goaf areas based on genetic algorithms. Background Technology

[0002] With the country's vigorous promotion of new infrastructure construction, subways are gradually becoming an indispensable new mode of transportation in urban development. Ensuring the stability of subway tunnels is a major technical problem that must be solved during construction. my country's coal resources are widely distributed. On the one hand, with the mining of coal mines, the area of ​​goaf areas is constantly increasing, urgently requiring the introduction of new technologies to manage goaf areas. On the other hand, with the acceleration of urban construction, it is inevitable to utilize old goaf areas to build various transportation facilities.

[0003] Shallow coal seams often have low stress levels, and the deterioration pattern of the geological structure after mining has its own unique characteristics. The recompaction effect in the center of the goaf is limited after sufficient mining. When constructing subway tunnels in goaf areas, the goaf will undergo displacement and deformation under external disturbances, causing uneven ground settlement and subsequently affecting the normal use of the subway structure and surface buildings. Simultaneously, during construction, the lateral pressure of unremoved gas in the goaf increases. When the gas pressure approaches a dangerous critical value, coal and gas explosions are likely to occur.

[0004] After mining is completed, the abandoned coal mine goaf is partially filled by collapsed overburden, while another part forms residual space, exhibiting a distinct "three-zone" characteristic. Residual space generally appears above the short-arm (pillar-type) mining face, formed due to insufficient collapse of the overburden. Another part appears near the boundary of the mining face; in this part, due to the certain rigidity of the overburden, a cantilever is formed at the edge of the goaf, preventing the overburden from collapsing and thus creating space. A third part is the ablation zone within the overburden; because the rigidity of the upper rock mass is greater than that of the lower rock mass, ablation occurs during rock strata movement, thus forming space.

[0005] Traditional grouting methods include:

[0006] ① Full grouting method

[0007] The entire goaf was filled with supporting overburden. The method used was dry filling, which involved transporting waste rock by vehicles in the tunnel, and wet filling, which involved grouting. The grouting materials mainly included fly ash and cement mortar.

[0008] ② Point grouting method

[0009] Point-based localized grouting can be used to form columns to support the overlying rock in the goaf, reduce the span between goaf sections, and prevent roof collapse. Alternatively, pile foundations can be used to locally support surface buildings. For irregular goaf areas, the main goal of remediation is to eliminate the safety hazards caused by the potential chain reaction of instability due to residual coal pillars within the goaf area.

[0010] ③ Grouting and filling method for overburden separation

[0011] Grouting is injected into the delamination and cracks of the overburden fault zone and bending zone of the mining area through drilling, forming a rigid and integral rock slab structure that effectively resists the upward development of the old mining goaf, ensuring that the surface only experiences relatively balanced subsidence and guaranteeing the safety of surface structures.

[0012] Currently, the more advanced technical measures used in the industry for treating complex, irregular, strip-shaped coal mine goaf areas include the following:

[0013] ④ Strip grouting method

[0014] The protected objects are the building complex to be built. The scope of the goaf treatment is defined according to the boundary angle. Within the treatment scope, multiple strip-shaped grouting and filling strips are arranged at intervals along the coal seam strike or dip. Grouting is carried out at the location of the grouting and filling strips using grouting equipment. The filling body formed by grouting and filling together with the coal pillar in the goaf form a structural support.

[0015] ⑤ Methods for reinforcing goaf areas based on geological exploration

[0016] First, exploration is conducted to determine the thickness, depth, density, location of key strata, fracture distance, and post-mining location. Next, based on boreholes at different locations, the location of the goaf roof is determined, the actual subsidence value of the basic roof along the dip is fitted, and then the theoretical subsidence value of the basic roof is calculated. Finally, the location of the grouting area and the grouting filling width are determined by combining the fracture distance and location of the key strata.

[0017] ⑥ Integrated Management Method for Goaf Areas

[0018] First, the goaf is filled with gangue, followed by grouting. The solidified gangue cementitious body has strong stability, enabling the goaf after strip mining to regain its load-bearing capacity, enhancing its overall strength, and reducing the load on the coal pillars on both sides. Next, grouting is applied to the fissures and delaminations in the goaf, allowing the overlying strata and grout to solidify and cement together, reconnecting the previously fractured strata and preventing further collapse of the overlying strata into the goaf. Finally, grouting is applied to the yield zone of the coal pillars, further enhancing their strength, preventing deformation, and ensuring the overall stability and load-bearing capacity of the goaf.

[0019] As mentioned above, current methods for reinforcing strip-shaped coal mine goaf areas include full grouting reinforcement, point grouting reinforcement, strip grouting reinforcement, geological exploration reinforcement, and gangue filling reinforcement. Among these, full grouting reinforcement and point grouting reinforcement are full-section grouting filling methods. Strip grouting reinforcement, geological exploration reinforcement, and gangue filling reinforcement are supplementary and reinforcing grouting reinforcement methods.

[0020] In full-section grouting filling methods, the full grouting method achieves good filling results. However, strip-shaped goafs are characterized by long extension ranges and unclear orientations, requiring large grouting volumes and resulting in high goaf treatment costs. Therefore, it is unsuitable for treating large-scale goafs below large-scale building areas or large-scale goafs. Point grouting covers a large area, making it difficult to precisely reinforce coal pillars and failing to eliminate hidden dangers. Moreover, local filling of coal mine goafs often only allows for point filling, mainly suitable for treating regular goafs and smaller-scale goafs directly below buildings. For deep, large-scale goafs, point grouting is insufficient to form structural support, and the grouting strength is inadequate to eliminate the risk of sudden surface subsidence due to coal pillar instability. Overburden separation grouting filling technology is mainly suitable for situations where rock strata have significant differences in lithology, mining affects rock strata that cannot move synchronously, and the separation space is large and relatively long, allowing for timely grouting filling. However, the conditions for using overburden separation grouting are quite demanding, making it difficult for many mines to achieve. Compared to separation grouting during mining operations, the space for separation grouting in the overburden of goaf areas is smaller, making it difficult to guarantee the filling and settlement reduction effect. For irregular goaf areas, the space requiring treatment mainly exists within the goaf area, not in the overburden separation layer; therefore, overburden separation grouting technology is not suitable for irregular goaf areas. In the supplementary reinforcement grouting method, the strip grouting filling method requires the original goaf coal pillar area and the filling body to form a structural support. Moreover, it protects surface buildings, without considering the protection of underground structures. The integrated goaf treatment method uses gangue instead of traditional cement / cement mortar to treat the goaf. This method can treat large-scale goaf areas, but for small-scale strip-shaped goaf areas, it is prone to problems such as incomplete filling and difficulty in complete grout filling. Summary of the Invention

[0021] The purpose of this invention is to address the aforementioned problems and shortcomings of existing technologies by designing a genetic algorithm-based method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goaf areas. This invention proposes a solution for efficient, rapid, and cost-effective reinforcement of goaf areas once their approximate extent and orientation are known.

[0022] A method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goaf areas based on genetic algorithms includes the following steps:

[0023] Step 1: Divide the irregular and complex strip-shaped goaf in the coal mine into regular goaf areas;

[0024] Step 2: Use sleeve valve pipes to perform double-liquid grouting and sealing on the segmented regular goaf areas;

[0025] Step 3: Conduct borehole detection verification within the sealing area;

[0026] Step 4: Compact and inject cement grout into the sealed area after detection;

[0027] Step 5: Use a genetic algorithm to optimize the selection of grouting equipment locations, and find the location where the sum of the distances between the grouting equipment and the grouting hole is the shortest as the location for the grouting equipment.

[0028] Furthermore, in step 1, the irregular goaf area is divided into rectangles or trapezoids according to the plane and longitudinal section.

[0029] Furthermore, in step 2, double-liquid grouting holes are drilled in a quincunx pattern, paired in pairs, to ensure the thickness of the double-liquid grout sealing wall formed after grouting while also taking into account the size of the underground structure. The double-liquid grout consists of cement, water, and water glass, with a mass ratio of 1:1.38:0.3. The double-liquid grout is injected through a sleeve valve pipe, so that the original soil and double-liquid grout in the sealing area can be fully and quickly bonded into a whole.

[0030] Preferably, during step 2, when performing double-liquid grouting, after the lower layer of double-liquid grout has been filled and compacted to a strength of 2MPa or higher, the grouting pipe is slowly lifted to fill the upper section. The lifting speed is ≤0.5m / min to prevent the grout from flowing easily and making it difficult to form a complete sealing wall before it has been properly bonded to the surrounding rock mass.

[0031] Furthermore, based on whether the longitudinal profile of the goaf is distributed above the structures, goafs are divided into two types: those distributed above the structures are shallow strip-shaped goafs, and those distributed below the structures are deep strip-shaped goafs.

[0032] For shallow, strip-shaped goaf areas, step 4 employs surface grouting.

[0033] For deep strip-shaped goaf areas, step 4 includes the following steps to ensure that the grouting holes can completely penetrate the shallow goaf area and the moderately weathered rock layer overlying the deep goaf area, and that the grouting slurry can fully fill the deep coal mine goaf area:

[0034] Step 4.1: Use a drilling rig to form holes. The hole depth should be based on entering the moderately weathered rock layer. When drilling, use the skip drilling method and arrange the holes in a quincunx pattern.

[0035] Step 4.2: After drilling, the steel casing is then installed. The lower end of the steel casing contacts the moderately weathered rock layer, and the upper end protrudes above the ground.

[0036] Step 4.3: After the steel casing is lowered, the expansion-type grout stop plug on the outside of the grouting pipe is also inserted into the steel casing;

[0037] Step 4.4: One end of the expansion grout stop plug is closed, and the other end is connected to an air inflator. First, inflate the expansion grout stop plug until it completely fills the steel sleeve, then start injecting ultrafine cement grout. When the grouting pressure reaches the specified value and the grout overflows to the ground, stop grouting and wait for the grout to solidify to complete the pipe solidification.

[0038] Step 4.5: After the pipe is solidified, the drilling rig is lowered back into the borehole. The diameter of the second borehole is smaller than that of the first borehole, and it is driven directly into the deep goaf area.

[0039] Step 4.6: After drilling, remove the mud from the hole and let it stand for 10 minutes to remove the gas inside the hole;

[0040] Step 4.7: Prepare cement mortar, insert the grout stop plug and grouting pipe for grouting;

[0041] Step 4.8: After the grouting reaches the required level, release the pressure and pull out the grouting pipe and the stop plug, seal the hole and proceed with the grouting of the next hole.

[0042] Furthermore, step 5 includes the following conditions:

[0043] 5) Except in cross-goaf areas, grouting equipment shall not be used in the same area across different goaf areas;

[0044] 6) The overlapping of upper and lower goaf areas will increase the amount of grouting required;

[0045] 7) When grouting equipment is used simultaneously in the same goaf, the impact of overlapping construction work is not considered;

[0046] 8) The different times of double-liquid grouting for sealing the edge and single-liquid grouting within the sealing zone need to be considered.

[0047] Furthermore, step 5 includes the following steps:

[0048] Step 5.1: Construct the grouting equipment set P = {P1, P2, P3, ..., P...} j}, where j is the number of grouting equipment, P1, P2, P3 and P j These represent the coordinates of the first, second, third, and j-th grouting equipment, respectively.

[0049] Step 5.2: Construct the grouting point set Q = {Q1, Q2, Q3, ..., Q...} t}, where t is the number of holes, Q1, Q2, Q3 and Q t Let represent the coordinates of the first, second, third, and t-th borehole points, respectively;

[0050] Step 5.3: Construct the set of grouting point locations from the grouting equipment, QP = {P1Q1, P1Q2, ..., P1Q...} t P2Q1, ..., P2Q t ... P j Q t ...}, where P j Q t Let be the distance between the j-th grouting equipment and the t-th borehole;

[0051] Step 5.4: Divide the strip-shaped coal mine goaf into four categories and construct a coal mine goaf type set Z = {I, II, III, IV}, where type I is a non-connected coal mine goaf, type II is a cross-shaped coal mine goaf, type III is an adjacent coal mine goaf, and type IV is a superimposed coal mine goaf.

[0052] Step 5.5: 1) For Type I goaf, grouting is performed by drilling in a quincunx pattern for each independent goaf; 2) For Type II goaf, after drilling in a quincunx pattern, overlapping parts can be grouted in the same area, and relatively independent parts can be grouted in two separate goafs; 3) For Type III goaf, after drilling in a quincunx pattern, overlapping and adjacent parts are grouted in the same area; 4) For Type IV goaf, grouting is performed in the same area.

[0053] Furthermore, in step 5, integer gene codes are generated according to the spacing between borehole positions during encoding. Several sets of grouting equipment are initially set according to the goaf type. Each grouting equipment and its adjacent grouting hole form a gene of length P. The grouting time for each grouting hole is the same for type I, II, and III goafs. For type IV goafs, due to the existence of vertical stacking, the grouting time for each grouting hole is longer than that for other types of goafs. For type IV goafs, the ratio of the grouting time consumed during grouting to the grouting time of conventional shallow goafs is converted into a distance ratio. An amplification factor ζ is set according to empirical values. The generated initial gene sequence group is imported into the genetic algorithm model. After fitness calculation, roulette wheel selection, crossover, and mutation operations, offspring are generated. Through continuous iteration, the most suitable number and layout of grouting equipment are finally obtained.

[0054] Preferably, the magnification factor ζ satisfies:

[0055]

[0056] Among them, T 深层 T represents the time consumed for grouting each deep grouting hole. 浅层 QP represents the time consumed for grouting the corresponding upper shallow grouting holes. 深层 QP represents the distance between the grouting equipment and each deep grouting hole. 浅层This indicates the distance between the grouting equipment and the corresponding shallow grouting hole, due to T 深层 T 浅层 QP was determined through actual on-site measurements. 浅层 It is obtained through distance measurement, via QP 浅层 and ζ inverse calculation QP 深层 It is then incorporated into the initial population of the subsequent genetic algorithm.

[0057] Furthermore, a genetic algorithm is used to optimize the dual-liquid grouting sealing pipeline: 1) For Type I goaf, expand the goaf distribution range by 3m to form a double-row borehole with a thickness of 2m, and treat them separately as relatively independent goaf areas; 2) For Type II goaf, treat the overlapping part of the goaf as a whole and expand it by 3m to form a rectangular double-row sealing hole, and treat the relatively independent position as a Type I goaf area; 3) For Type III goaf, treat the adjacent part as a whole and expand it by 3m to form a rectangular double-row sealing hole; 4) For Type IV goaf, perform secondary sealing on the underlying goaf area, and expand it by 3m and then 10m to form a double sealing hole.

[0058] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0059] The purpose of this invention is to address the aforementioned problems and shortcomings of existing technologies by designing a genetic algorithm-based method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goaf areas. This invention proposes a solution for efficient, rapid, and cost-effective reinforcement of goaf areas once their approximate extent and orientation are known.

[0060] 1. This invention uses a genetic algorithm to make intelligent auxiliary decisions on the layout of grouting pipelines for locations where potential goaf areas may exist, which can reduce the idle time of grouting equipment and improve on-site construction efficiency.

[0061] 2. The segmented grouting reinforcement method proposed in this invention can meet the requirements for safe passage of structures without reinforcing the entire goaf.

[0062] 3. This invention has a wide range of applications, suitable for reinforcing various complex strip-shaped coal mine goafs, considering goafs of different locations and shapes from a three-dimensional perspective of underground space. Irregular strip-shaped goafs are divided into regular volumes from planar and longitudinal section perspectives and then processed separately.

[0063] 4. The present invention has strong geological adaptability. By using casing and secondary drilling grouting, it can achieve good reinforcement treatment effect for goaf areas of different depths and overlying rock strata.

[0064] 5. This invention uses fast-setting dual-liquid grouting to seal the goaf, preventing the overflow of grout from the compaction grouting in the later segmented area and causing subsidence of the surrounding strata, thus ensuring good safety.

[0065] 6. This invention divides the strip-shaped goaf in coal mines, seals the edges with a two-liquid grout, and then reinforces the goaf by injecting cement grout into the divided areas. This avoids the environmental pollution and material waste caused by injecting cement grout into the entire goaf, which would not solidify in time and overflow everywhere. It has high economic benefits. Attached Figure Description

[0066] Figure 1 Flow chart of the complex strip-shaped coal mine goaf segmentation grouting process designed for this invention;

[0067] Figure 2 This is a schematic diagram of a strip-shaped coal mine goaf area according to the present invention;

[0068] Figure 3 This is a schematic diagram of the planar division of the goaf area according to the present invention;

[0069] Figure 4 This is a schematic diagram of the longitudinal section of the goaf area according to the present invention;

[0070] Figure 5 This is a flowchart of the double-liquid grouting and sealing process for the sleeve valve tube of the present invention;

[0071] Figure 6 This is a flowchart of the compaction grouting process within the sealing area of ​​the present invention;

[0072] Figure 7 This is a flowchart of the compaction grouting process within the sealing area;

[0073] Figure 8 This is a schematic diagram illustrating the optimization of the pipeline using a genetic algorithm in this invention.

[0074] Figure 9 This is a schematic diagram illustrating different types of goaf areas according to the present invention;

[0075] Figure 10 This is a schematic diagram of the optimized zoning for goaf compaction grouting according to the present invention;

[0076] Figure 11 This is a layout diagram of the goaf compaction grouting equipment of the present invention;

[0077] Figure 12 This is a schematic diagram of the optimized zoning for dual-liquid slurry edge sealing in the goaf area according to the present invention;

[0078] Figure 13 This is a schematic diagram of the rigid foundation covering and reinforcement structure of the present invention;

[0079] Figure 14 This is a schematic diagram of the search results for the minimum grouting equipment using the genetic algorithm of this invention. Detailed Implementation

[0080] The following description, in conjunction with the accompanying drawings and specific implementation methods, provides a more detailed explanation of the present invention: a method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goaf areas based on genetic algorithms.

[0081] Example 1

[0082] This invention provides a method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goaf areas based on genetic algorithms, such as... Figure 1 As shown.

[0083] Complex strip-shaped coal mine goafs are characterized by their long extension range, large length-to-width ratio, irregular shape, large dip angle, and overlapping structure. This patent proposes a segmented grouting process that segments the complex and irregular goaf, then performs compaction grouting in the segmented, more regular goafs to reinforce the strata and protect the stability of underground structures. The specific implementation process is as follows:

[0084] (1) Division of goaf

[0085] Complex strip-shaped coal mine goafs exhibit irregular three-dimensional spatial distribution underground. Therefore, it is necessary to first divide the irregular goafs into regular shapes such as rectangles or trapezoids according to the plan and longitudinal sections. The four sides of the rectangles or trapezoids are enclosed along the boundary of the goaf to form a closed shape. The division principle is as follows:

[0086] 1) Planar segmentation must meet the requirements of grout fluidity and grouting pressure of the grouting machine during the subsequent compaction grouting in the segmented area;

[0087] 2) Planar division must meet the requirement of completely covering the underground structure, and the width is generally between 8 and 12 meters;

[0088] 3) Planar segmentation: The segmentation surface needs to be stable and needs to form a certain thickness, generally controlled within 2 meters;

[0089] 4) Planar segmentation: The segmentation zone should be arranged perpendicular to the direction of the goaf. If the strata are hard and drilling is difficult, it can be arranged at a certain angle to the goaf, depending on the geological survey. The angle should not be too large, so as to avoid the hard strata shown in the geological survey report.

[0090] 5) Planar segmentation: If there are intersecting strip-shaped goaf areas, the size of the intersecting area should be considered separately: If the intersecting area accounts for 1 / 4 or more of the overall goaf area, it can be treated as a karst cavity. If the intersecting area is small, the intersecting area can be left unsegmented, and only the extension of the intersecting area can be segmented.

[0091] 6) Planar division: If there are overlapping strip-shaped goaf areas (the upper and lower goaf areas overlap or are at a small angle), they can be merged or closely arranged (using two sealing walls with close distance).

[0092] 7) Planar division: If an adjacent goaf is encountered, the length of the sealing wall can be increased and the sealing can be merged (at this time, it can be considered as the goaf changing cross section widening).

[0093] 8) When dividing the longitudinal section, the performance of the edge sealing equipment and the burial depth of the structure must be taken into account; the depth of the division shall not exceed the drilling depth of the equipment and shall not be less than the burial depth of the structure.

[0094] 9) The longitudinal section division must meet the requirement of completely covering the underground structure. The depth of the reinforced foundation of the division should be comprehensively considered in combination with the load on the underground structure and within the rigidity angle of the stratum.

[0095] 10) Longitudinal section division: Longitudinal section division is not required for mined-out areas that are too deep or have a long vertical distance from the bottom of the structure.

[0096] 11) Longitudinal section segmentation: If drilling is difficult due to hard strata during the construction of the edge sealing wall, the edge sealing of this section can be stopped, and the edge sealing can be carried out in sections after expanding outwards by a certain distance (to cross the hard strata).

[0097] (2) Double-liquid grouting and sealing of sleeve valve tube

[0098] Based on the above principles for goaf segmentation, sleeve valve pipes are used to perform dual-liquid grouting segmentation on various complex strip-shaped goaf areas. The main process is as follows: Figure 5 As shown:

[0099] The grouting holes are drilled in a quincunx pattern, paired in pairs, to ensure the thickness of the double-liquid grout sealing wall after grouting while also accommodating the dimensions of the underground structure. The double-liquid grout mix ratio is cement:water:water glass = 1:1.38:0.3 (mass ratio). 42.5 grade ordinary Portland cement is used, and the water glass modulus m = 2.4–3.4 (Baumé degree Be = 30–40). The grout is injected by a grouting pump, allowing the cement grout filling the goaf to be fully compressed and bonded into a cohesive whole. During dual-liquid grouting, the grouting pipe can only be slowly raised to fill the upper section after the lower layer of dual-liquid grout has filled and compacted to a certain strength (above 2MPa). The grouting pipe should be raised at a speed not exceeding 0.5m / min before the dual-liquid grout initially sets. It should not be too fast or too slow (if the grout is raised too fast, it has not yet formed strength and has not yet cemented with the surrounding rock mass, making it easy to flow and difficult to form a complete sealing wall; if the grout is raised too slowly, it has already solidified, making it difficult to raise the grouting pipe).

[0100] (3) Detailed exploration of boreholes within the sealing area

[0101] like Figure 6As shown, a second detailed exploration was conducted within the sealing area. First, a trial exploration of the goaf was carried out within the double-liquid grout sealing wall area. Using the boreholes revealing the goaf as reference points, the density of boreholes was increased and spread outwards in a quincunx pattern with a 2×2m spacing. The boreholes also served as grouting holes, and several boreholes were selected at the top of the boreholes as venting holes. At least one venting hole was required per borehole, with additional venting holes added at intervals exceeding 4m, until no more karst was revealed by the boreholes. If the bottom layer is a sand layer or other medium to high permeability layer, the detailed exploration range of the boreholes within the sealing area needs to be appropriately increased according to the actual situation. When the base is a limestone stratum, boreholes need to be drilled to a depth of at least 5m below the base or to a stable aquitard.

[0102] (4) Compacting grouting in the goaf

[0103] like Figure 7 As shown, the identified strip-shaped goaf areas within the sealed area are divided into two types in longitudinal section: shallow strip-shaped goaf areas, distributed above the structures, with generally low overlying rock strength; and deep strip-shaped goaf areas, distributed below the structures, with greater burial depth and generally higher overlying rock strength. The shallow strip-shaped goaf areas can be treated using conventional surface grouting methods, which will not be elaborated upon here. Regarding the treatment of deep strip-shaped coal mine goaf areas, the following explanation is provided:

[0104] Using a geological drilling rig or a multi-functional drilling rig, the initial borehole diameter can be appropriately enlarged, with the drilling depth determined by reaching the moderately weathered rock strata. A skip-drilling method is used, with holes arranged in a staggered pattern. After drilling, a steel casing with a slightly smaller diameter is installed. The lower end of the steel casing contacts the moderately weathered rock strata, while the upper end protrudes above the ground to a certain height. After the casing is lowered, an expandable grout stopper is inserted into the casing along with the grouting pipe. One end of the expandable grout stopper is sealed, and the other end is connected to an air inlet pipe. The grout stopper is first inflated until it completely fills the casing before injecting ultrafine cement grout. Grouting is stopped when the grouting pressure reaches the specified value and grout overflows to the ground. The grout solidifies, indicating that the casing is now solidified.

[0105] After the casing was solidified, the drilling rig was lowered back into the borehole. The second borehole had a smaller diameter than the first and was drilled directly into the deep goaf. After drilling, the mud in the borehole was removed and allowed to stand for 10 minutes to purge any methane gas. Cement mortar was then prepared with a cement:sand:water ratio of 1:6:1.1 (by mass), using 42.5R ordinary Portland cement. The grout stopper and grouting pipe were lowered again for grouting. Once the grouting requirements were met, the pressure was released, and the grouting pipe and grout stopper were removed to seal the borehole before proceeding to the next borehole.

[0106] (5) Pipeline optimization based on genetic algorithm

[0107] As mentioned above, the boreholes are arranged in a 2m*2m staggered pattern within the goaf area. However, the amount of grout required during processes such as double-liquid grout sealing and compaction grouting within the goaf is substantial. If a separate drilling and grouting system is installed for each grouting hole, the required equipment quantity would be enormous and uneconomical. Conversely, if the number of grouting devices is insufficient, the goal of efficiently and safely reinforcing the goaf cannot be achieved. Therefore, the grouting pipeline needs to be optimized.

[0108] A genetic algorithm is used to optimize the pipeline. The optimization process is as follows: Figure 8 As shown:

[0109] The chromosome encoding method uses integer encoding, where each chromosome represents the matching of each grouting device with a grouting hole. Therefore, the pipeline optimization problem can be transformed into the problem of minimizing the sum of the distances between n grouting devices and their corresponding grouting holes. The following assumptions are made:

[0110] 1) Except in cross-goaf areas, grouting equipment shall not be used in the same area across different goaf areas;

[0111] 2) Consider the increased demand for grouting equipment due to the overlapping of upper and lower sections in the goaf;

[0112] 3) Grouting equipment is used simultaneously in the same goaf, without considering the impact of overlapping construction work;

[0113] 4) Consider the different times required for double-liquid grouting and single-liquid grouting.

[0114] The mathematical model is as follows:

[0115] 1) Grouting equipment set P = {P1, P2, P3, ..., P} j}, where j is the number of grouting equipment;

[0116] 2) Grouting point set Q = {Q1, Q2, Q3, ..., Q...} t}, where t is the number of boreholes;

[0117] 3) The set of grouting point locations relative to the grouting equipment location QP = {P1Q1, P1Q2, ..., P1Q} t P2Q1, ..., P2Q t ,

[0118] ... P j Q t ...}, where P j Q t Let t be the distance between the t-th point and the j-th grouting equipment;

[0119] 4) The time matrix for double-liquid grouting and edge sealing using the equipment is U, and the time matrix for single-liquid grouting using the equipment is C.

[0120] 5) The set of coal mine goaf types Z = {I, II, III, IV}, where type I refers to non-contiguous coal mine goafs, such as... Figure 9 As shown in (a); Type II is a cross-shaped coal mine goaf, such as... Figure 9 (b) shows that Type III is a goaf area in a nearby coal mine, such as Figure 9 (c) shows that Type IV is a goaf in a coal mine with overlapping upper and lower sections, such as... Figure 9 As shown in (d).

[0121] ① Optimization of compaction grouting pipeline

[0122] The following optimizations are made for different types of goaf areas:

[0123] 1) Type I goaf

[0124] Type I goaf is spatially represented as two separate goaf areas. After using the vertical and planar division rules mentioned above, and drilling in a 2*2m quincunx pattern, the two goaf areas are relatively far apart and are treated as relatively independent goaf areas.

[0125] 2) Type II goaf

[0126] Type II goaf spatially manifests as two goafs that partially overlap in location, while the other part is relatively independent. In this case, after drilling the goafs in a 2*2m quincunx pattern, the overlapping part can be grouted as the same area, while the relatively independent part can be grouted as two separate goafs.

[0127] 3) Type III goaf

[0128] Type III goaf spatially manifests as two goafs partially overlapping and adjacent to each other. In this case, after drilling the goafs in a 2*2m quincunx pattern, the overlapping and adjacent parts can be grouted separately as the same area.

[0129] 4) Type IV goaf

[0130] Type IV goaf is spatially represented by two goafs vertically overlapping each other. In this case, grouting can be carried out in the same area, but the grouting process and time are different at different locations.

[0131] Optimized graphics Figure 10 The diagrams shown are: Schematic diagrams of optimized grouting zones for Type I goaf, Type II goaf, Type III goaf, and Type IV goaf.

[0132] During encoding, integer gene codes are generated based on the borehole location spacing (2*2m). Several sets of grouting equipment are initially set up according to the goaf type. Each grouting equipment and its adjacent grouting holes can form a gene of length P (the length of P is determined by each grouting equipment and the grouting holes connected to it). It is assumed that the grouting time for each grouting hole is the same for type I, II, and III goafs, while the grouting time for each grouting hole is longer for type IV goafs due to the presence of vertical overlap. An amplification factor ζ is given based on the different grouting times. For ease of calculation, this amplification factor can be converted into an increase in distance. The generated initial gene sequence group is imported into the genetic algorithm model. After fitness calculation, roulette wheel selection, crossover, and mutation operations, offspring are generated. Through continuous iteration, the most suitable number and placement of grouting equipment are finally obtained.

[0133] Import the model, and the optimized pipeline layout is as follows: Figure 11 As shown in the figure, the circular dots represent grouting points, and the rectangular dots represent the locations of the grouting equipment.

[0134] ② Optimization of dual-liquid slurry edge sealing pipeline

[0135] The following optimizations are made for different types of goaf areas:

[0136] 1) Type I goaf

[0137] Type I goaf is spatially represented by two separate goaf areas. Two rows of boreholes, each 2 meters thick, are formed by extending 3 meters outward from the goaf area. The two goaf areas are relatively far apart and are treated as relatively independent goaf areas.

[0138] 2) Type II goaf

[0139] Type II goaf spatially manifests as two goafs that partially overlap, while the other part remains relatively independent. In this case, the overlapping part of the goaf is treated as a whole and expanded outward by 3m to form a rectangular double-row sealing hole, while the relatively independent part is treated as a Type I goaf.

[0140] 3) Type III goaf

[0141] Type III goaf spatially manifests as two goaf areas partially overlapping and adjacent to each other. In this case, the adjacent part is treated as a whole and expanded outward by 3m to form a rectangular double-row sealing hole.

[0142] 4) Type IV goaf

[0143] Type IV goaf spatially manifests as two goafs vertically overlapping. In this case, grouting can be carried out in the same area. However, due to the depth of the underlying goaf, secondary sealing of the underlying goaf is required. Double (4 rows) sealing holes are formed by expanding outward by 3m and then by expanding outward by 10m.

[0144] Optimized graphics as follows Figure 12 The diagrams shown are: Schematic diagrams of optimized zoning for double-liquid grout sealing in Type I goaf, Type II goaf, Type III goaf, and Type IV goaf.

[0145] During encoding, integer gene codes are generated based on the borehole location spacing. Several sets of sleeve valve grouting equipment are initially set up according to the goaf type. Each grouting equipment and its adjacent grouting holes can form a gene of length P (the length of P is determined by each grouting equipment and the grouting holes connected to it). It is assumed that the grouting time for each grouting hole is consistent for type I, II, and III goafs, while the grouting time for each segment of type IV goaf is longer than other types due to the formation of four sealing walls. An amplification factor ζ is given based on the different grouting times. For simplified calculation, this amplification factor can be converted into an increase in distance. The generated initial gene sequence group is imported into a genetic algorithm model. After fitness calculation, roulette wheel selection, crossover, and mutation operations, offspring are generated. Through continuous iteration, the optimal number and layout of sleeve valve dual-liquid grouting equipment are finally obtained.

[0146] Example 2

[0147] In addressing the requirement for complete enclosure of underground structures, the rigid angle principle used in foundations is innovatively introduced into deeply buried underground structures. The deeply buried underground structure is considered a surface building covered by soil, and the solidified enclosure surrounding the underground structure serves as the initial foundation.

[0148] Vertical loads acting on the bottom surface of underground structures include the structure's self-weight, the weight of the overlying soil, and live loads within the structure. Assuming a linear distribution of pressure at the foundation bottom, and uniform distribution under a central load, the foundation under a central load, calculated according to its bearing capacity design value, should satisfy the following condition:

[0149] p≤f

[0150] Under the action of a central load, the following formula applies:

[0151]

[0152] That is, G = γ × d × A

[0153] In the formula: d is the foundation depth; A is the foundation base area; γ is the soil weight (buoyancy weight is taken below the groundwater level). For strip foundations, A = b, where b is the foundation width, G is the structural self-weight, and F is the sum of the overburden and live load within the structure. P is the foundation load, and f is the allowable load of the foundation. Therefore:

[0154]

[0155] Once the width of the rigid foundation is determined, the height of the reinforced foundation is determined according to the requirements of the rigidity angle. If the width of the foundation of the underground structure is b, the outward extension lengths on both sides of the rigid foundation are: b0 is the height of the top of the structure, see Figure 13 According to the structural rigidity angle requirements:

[0156]

[0157] Therefore, for the covering of underground structures, the minimum depth of the solidification layer is: In the formula, h is the distance from the bottom surface of the structure to the bottom surface of the reinforced body, and a is the rigidity angle, such as... Figure 13 As shown.

[0158] Example 3

[0159] The search for the minimum grouting equipment based on the genetic algorithm is as follows:

[0160] The following assumptions are made in the grouting equipment (two-component grout / single-component grout) preparation model for goaf areas:

[0161] 1) The quantity of grouting equipment and its supporting grout preparation should meet the grouting volume and grouting time requirements of the surrounding grouting points, and should also meet the grouting volume requirements of the overlapping goaf areas within its coverage area.

[0162] 2) Grouting of a single hole is completed by only one set of equipment.

[0163] 3) There is a certain distance between the strips and the goaf, and it is not considered that one piece of equipment can supply multiple goaf sections.

[0164] Based on the above assumptions, a shortest distance search model is established. The objective function is to minimize the sum of the products of the grouting time and the grouting volume of each grouting hole at different locations. The objective function is:

[0165]

[0166] The constraint condition is: ∑ j∈Mi Z ij =1, i∈N

[0167] Z ij ≤h j , i∈N, j∈Mi

[0168] ∑ j∈Mi h j =p

[0169] Z ij h j ∈{0, 1}, i∈N, j∈M i

[0170] d ij≤s

[0171] Where N = {1, 2, ..., n} is the set of indices of all demand points, and Mi represents the alternative grouting equipment whose distance to demand point i is less than s, i ∈ N. ω i This indicates the required quantity of grouting equipment at each grouting point; d ij Z represents the distance from grouting point i to grouting equipment j that can meet its grouting requirements; ij Z is a 0-1 variable representing the correspondence between grouting points and grouting equipment. When grouting point i is supplied by equipment i, then Z is denoted as Z. ij =1, otherwise 0. h j It is a 0-1 variable. When j=1, it means that point j is the selected grouting equipment position.

[0172] An initial population is randomly generated in the feasible solution space. Each grouting point and its associated grouting equipment scheme can form a gene encoding of length P. For the minimum grouting equipment selection problem, the objective function of the above equation can be written as:

[0173]

[0174] In the formula F v Let A be the objective function, C be the penalty function, and A be the penalty function. v A genetic function designed for the shortest distance model of grouting equipment layout in strip coal mine goaf areas.

[0175] Fitness S between gene codes v,s It can be determined by the following formula:

[0176]

[0177] Where, k s，v is the number of identical positions in gene V and gene S; L is the gene length.

[0178] The concentration of introduced genes C v , which represents the proportion of similar genes in the population, i.e.:

[0179]

[0180] Where M represents the total number of genes. T is a pre-set threshold.

[0181] In a gene population, the expected reproductive probability of each individual is determined by the gene concentration C of the parent and offspring. v and objective function A v It is decided jointly by two parties. That is...

[0182]

[0183] In the formula, 'a' is a distribution constant between 0 and 1. That is, the higher the individual fitness, the greater the expected reproductive probability; the higher the individual concentration, the lower the expected reproductive probability. This encourages individuals with high fitness while inhibiting individuals with high concentration, thus ensuring individual diversity.

[0184] During gene selection, a roulette wheel selection mechanism is used, with single-point crossover employed. Mutations are performed by randomly selecting mutation sites.

[0185] Figure 14 This diagram illustrates the results of the genetic algorithm's search for the minimum grouting equipment requirement. This invention employs a genetic algorithm to provide intelligent auxiliary decision-making for grouting pipeline layout at locations identified in previous explorations as potential goaf areas. This reduces idle grouting equipment and improves on-site construction efficiency.

[0186] This invention proposes a method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goaf areas based on a genetic algorithm. The above embodiments are only for illustrating the technical concept and features of this invention, and are intended to enable those skilled in the art to understand the content of this invention and implement it accordingly. They should not be construed as limiting the scope of protection of this invention. All equivalent changes or modifications made in accordance with the spirit and essence of this invention should be covered within the scope of protection of this invention.

Claims

1. A method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goaf areas based on genetic algorithms, characterized in that, Includes the following steps: Step 1: Divide the irregular and complex strip-shaped goaf in the coal mine into regular goaf areas; Step 2: Use sleeve valve pipes to perform double-liquid grouting and sealing on the segmented regular goaf areas; Step 3: Conduct borehole detection verification within the sealing area; Step 4: Compact and inject cement grout into the sealed area after detection; Step 5: Use a genetic algorithm to optimize the selection of grouting equipment locations, and find the location where the sum of the distances between the grouting equipment and the grouting hole is the shortest as the location for the grouting equipment layout. Strip-shaped coal mine goaf areas are divided into four categories, constructing a set of coal mine goaf area types Z= Among them, Type I is a non-interconnected coal mine goaf, Type II is a cross-shaped coal mine goaf, Type III is an adjacent coal mine goaf, and Type IV is a superimposed coal mine goaf. 1) For Type I goaf, grouting is performed using a quincunx pattern of boreholes, treating each goaf as an independent goaf. 2) For Type II goaf, after drilling quincunx-patterned boreholes, overlapping portions are grouted in the same area, while relatively independent portions are grouted as two separate goaf areas. 3) For Type III goaf, after drilling quincunx-patterned boreholes, overlapping and adjacent portions are grouted in the same area. 4) For Type IV goaf, grouting is performed in the same area. During encoding, integer gene codes are generated according to the spacing between borehole locations. Several sets of grouting equipment are initially set according to the goaf type. Each grouting equipment and its adjacent grouting holes form a gene of length P. The grouting time for each grouting hole is the same for goaf types I, II, and III. For goaf types IV, due to the existence of vertical stacking, the grouting time for each grouting hole is longer than that for other types of goaf. For goaf types IV, the ratio of grouting time to the grouting time of conventional shallow goaf is converted into a distance ratio, and an amplification factor ζ is set according to empirical values. The generated initial gene sequence group is imported into the genetic algorithm model. After fitness calculation, roulette wheel selection, crossover, and mutation operations, offspring are generated. Through continuous iteration, the most suitable number and layout of grouting equipment are finally obtained.

2. The method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goaf areas based on genetic algorithms according to claim 1, characterized in that: Step 1: Divide the irregular goaf into rectangles or trapezoids according to the plane and longitudinal sections.

3. The method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goaf areas based on genetic algorithms according to claim 2, characterized in that: Step 2: Drill double-liquid grouting holes in a quincunx pattern, pairing them up in pairs to ensure the thickness of the double-liquid grout sealing wall formed after grouting while also taking into account the size of the underground structure. The double-liquid grout consists of cement, water, and water glass, with a mass ratio of 1:1.38:0.

3. The double-liquid grout is injected through a sleeve valve pipe, allowing the original soil and double-liquid grout in the sealing area to fully and quickly bond together into a whole.

4. The method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goaf areas based on genetic algorithms according to claim 3, characterized in that: In step 2, during the double-liquid grouting, after the lower layer of double-liquid grout has been filled and compacted to a strength of 2MPa or higher, the grouting pipe is slowly raised to fill the upper section. The raising speed is ≤0.5m / min to prevent the grout from flowing easily and making it difficult to form a complete sealing wall before it has been properly bonded to the surrounding rock mass.

5. The method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goaf based on genetic algorithm according to claim 1, characterized in that: Based on whether the longitudinal profile of the goaf is located above structures, goaf areas are divided into two types: shallow strip goaf areas located above structures and deep strip goaf areas located below structures. For shallow, strip-shaped goaf areas, step 4 employs surface grouting. For deep strip-shaped goaf areas, step 4 includes the following steps to ensure that the grouting holes can completely penetrate the shallow goaf area and the moderately weathered rock layer overlying the deep goaf area, and that the grouting slurry can fully fill the deep coal mine goaf area: Step 4.1: Use a drilling rig to form holes, with the hole depth determined by entering the moderately weathered rock layer. Use the skip drilling method and arrange the holes in a quincunx pattern. Step 4.2: After drilling, the steel casing is then installed. The lower end of the steel casing contacts the moderately weathered rock layer, and the upper end protrudes above the ground. Step 4.3: After the steel casing is lowered, the expansion-type grout stop plug on the outside of the grouting pipe is also inserted into the steel casing; Step 4.4: One end of the expansion grout stop plug is closed, and the other end is connected to an air inflator. First, inflate the expansion grout stop plug until it completely fills the steel sleeve, then start injecting ultrafine cement grout. When the grouting pressure reaches the specified value and the grout overflows to the ground, stop grouting and wait for the grout to solidify to complete the pipe solidification. Step 4.5: After the pipe is solidified, the drilling rig is lowered back into the borehole. The diameter of the second borehole is smaller than that of the first borehole, and it is driven directly into the deep goaf area. Step 4.6: After drilling, remove the mud from the hole and let it stand for 10 minutes to remove the gas inside the hole; Step 4.7: Prepare cement mortar, insert the grout stop plug and grouting pipe for grouting; Step 4.8: After the grouting reaches the required level, release the pressure and pull out the grouting pipe and the stop plug, seal the hole and proceed with the grouting of the next hole.

6. The method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goafs based on genetic algorithms according to claim 1, characterized in that, Step 5 includes the following conditions: 1) Except in cross-goaf areas, grouting equipment shall not be used in the same area across different goaf areas; 2) The overlapping of upper and lower goaf areas will increase the amount of grouting required; 3) Grouting equipment is used simultaneously in the same goaf, without considering the impact of overlapping construction work; 4) The different times of double-liquid grouting for sealing the edge and single-liquid grouting within the sealing zone need to be considered.

7. A method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goaf areas based on genetic algorithms, as described in claim 6, is characterized in that... Step 5 includes the following steps: Step 5.1: Construct the grouting equipment set P= Where j is the number of grouting equipment, , , and These represent the coordinates of the first, second, third, and j-th grouting equipment, respectively. Step 5.2: Construct the grouting point set Q= Where t is the number of boreholes, , , and Let represent the coordinates of the first, second, third, and t-th borehole points, respectively; Step 5.3: Construct the set of grouting point locations QP from the grouting equipment. ,in, Let be the distance between the j-th grouting equipment and the t-th borehole.

8. The method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goaf based on genetic algorithm according to claim 7, characterized in that: The magnification factor ζ satisfies: = = ； in, This indicates the time consumed for grouting each deep grouting hole. This indicates the time consumed for grouting the corresponding upper shallow grouting holes. This indicates the distance between the grouting equipment and each deep grouting hole. This indicates the distance between the grouting equipment and the corresponding shallow grouting hole. , This was determined through actual on-site measurements. It was obtained through distance measurement, via and ζ inverse calculation It is then incorporated into the initial population of the subsequent genetic algorithm.

9. A method for segmenting and reinforcing underground structures traversing complex strip-shaped coal mine goaf areas based on genetic algorithms, as described in claim 7, characterized in that: Genetic algorithms were used to optimize the double-liquid grouting sealing pipeline: 1) For Type I goaf, the boreholes were expanded 3m outward along the goaf distribution range to form a double row of holes with a thickness of 2 meters, and treated as relatively independent goaf areas; 2) For Type II goaf, the overlapping part of the goaf was treated as a whole and expanded 3m outward to form a rectangular double row of sealing holes, and the relatively independent position was treated as a Type I goaf area; 3) For Type III goaf, the adjacent part was treated as a whole and expanded 3m outward to form a rectangular double row of sealing holes; 4) For Type IV goaf, the underlying goaf was sealed twice, and the sealing holes were expanded 3m outward and then 10m outward to form a double sealing hole.

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