A method for coordinating the disposal of foundations of structures in old goaf and deep underground space

Abstract

The present invention discloses a method for the coordinated disposal of foundations of structures in old goaf areas and deep underground spaces, which specifically includes the steps of determining the current status of deep underground goaf areas, determining the scope of foundation treatment for structures to be built above the goaf areas, filling the goaf areas, constructing structures and heat pump systems, and extracting heat. This method for the coordinated disposal of foundations of structures in old goaf areas and deep underground spaces can achieve the construction of buildings on the surface above abandoned mine goaf areas, avoiding the waste of surface land resources, and heat-exchanging the raw water in the abandoned mine goaf areas through the heat pump system for heating the surface buildings above the goaf areas. The raw water after heat absorption is re-injected into the underground goaf areas through a purification device, and a purifier can be added to the water injection pipe through a purifier adding device. This can achieve the purification of the raw water in the abandoned mine goaf areas under the premise of "extracting heat without extracting water", thereby avoiding the water resources in the abandoned mine goaf areas from damaging the ecological environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource utilization and environmental protection, and specifically relates to a method for coordinated disposal of foundations of buildings and structures in old goaf areas and deep underground spaces. Background Art

[0002] Over time, as geological conditions change, abandoned mines often experience crack expansion, collapse, and water inrush, often due to human factors such as mine tunnels and goafs. This environment is completely different from that of a normal operating mine, while the surface can form subsidence areas, rendering the land unusable and generally preventing the construction of structures. However, even after a mine closes, the underground energy and surface land remain. With land resources for construction and traditional energy sources becoming increasingly scarce, failing to utilize the remaining resources of abandoned mines can easily lead to waste and potentially cause subsequent safety and environmental issues.

[0003] Generally, the development and utilization of abandoned mines usually utilizes the huge underground space resources in the goaf, such as using abandoned mines to build underground gas storage, using abandoned mines to dispose of low- and intermediate-level radioactive waste, etc. This is also the simplest and most effective way. Abandoned mines in my country usually have a lot of water resources, and these mine waters are not the original water resources of the mines themselves. After coal seam mining, the overlying rock strata are destroyed and displaced, forming three zones: the caving zone, the fracture zone, and the bending zone. The basic top rock layer of the goaf is further broken at the end position, forming a stable arc-shaped triangular rock block structure. The underground aquifer closer to the coal seam transports water to the abandoned mine through the water-conducting fracture zone and stores it under the arc-shaped triangular block structure of the goaf. If drainage is stopped after a mine is closed or abandoned, the water level in the abandoned mine goaf will rise rapidly. In addition, the contact between the mine water and the coal seams and rock strata makes its water quality poor and its hardness high. In particular, the old cellar water has a total hardness of about 30 to 76 degrees and a mineralization of about 1 to 9 g / L. It is a highly mineralized mine water that contains not only cement, suspended matter, coal slime and other substances, but also often contains metal sulfides and is prone to forming acidic mine water. Some abandoned mine goafs also contain organic matter and microorganisms, as well as problems such as high sulfate, high fluoride, high iron, high manganese, and excessive arsenic. It is usually not directly usable. Moreover, if the water resources in the abandoned mine goaf diffuse into the surrounding aquifers or underground rivers through mining cracks and faults, or even into artificial lakes on the surface, it will have a long-term impact on the local and surrounding groundwater environment and disrupt the balance of the ecosystem. Therefore, from the perspective of both abandoned mine resource utilization and environmental protection, the management of abandoned mine water resources and surface land resources is also a top priority. Summary of the Invention

[0004] In response to the problems existing in the above-mentioned prior art, the present invention provides a method for the coordinated disposal of the foundations of buildings and structures in old goafs and deep underground spaces. It adopts the principle of shallow filling and deep utilization, which can release the spatial resources of the land above the goaf, realize the utilization of water resources in the goaf, and avoid its damage to the ecological environment.

[0005] In order to achieve the above purpose, the method for coordinating the disposal of the foundation of the building structure in the old goaf and the deep underground space specifically includes the following steps:

[0006] Step 1: Determine the current status of deep underground goaf: Collect geological maps of abandoned mines, ore deposit distribution maps, mining engineering plan maps, and relevant surface deformation data;

[0007] Step 2: Determine the scope of foundation treatment for the structure to be built above the goaf:

[0008] ① Determine the ground treatment level according to the type of building to be constructed, and then determine the width d of the maintenance strip. s , the width of the maintenance zone is extended by the outline size of the proposed building structure s and the construction location determines the ground level treatment range;

[0009] ②Calculate the residual deformation of the ground:

[0010] With r as the main influencing radius, H as the mining depth, H0 as the average mining depth, and β as the main influencing angle,

[0011] θ is the maximum sinking angle, C is the sinking coefficient, l i is the calculated width of unit i, H i is the mining depth of unit i, then l i =H i ×C×tgθ;

[0012] (x i ,y i ) is the coordinate of the center point of unit i, then the amount of subsidence caused by unit i at any point on the ground (x, y) is

[0013]

[0014] P is the strike length of the working face, a is the horizontal distance of the working face along the inclined direction, if the goaf is a rectangle with the area of ​​0 to P and 0 to a, with W0 as the maximum subsidence value under the geological mining conditions, α as the inclination angle of the coal seam, q as the subsidence coefficient under full mining conditions, and m as the mining thickness of the coal seam, then W0 = mqcosα;

[0015] Then, the subsidence of any point on the ground surface above the goaf is

[0016]

[0017] Step 3: Goaf filling:

[0018] ① Assuming that there are n layers of underground space mined, none of which are filled, calculate the residual deformation of the ground surface. If the predicted subsidence of any point within the horizontal treatment range of the building ground meets the required surface deformation of the building, no filling is required. Otherwise, proceed to the next step.

[0019] ② Simulate dense filling of the shallowest first goaf, and leave the remaining n-1 layers unfilled. Calculate the residual deformation of the ground surface. If the predicted subsidence of any point within the horizontal treatment range of the building ground meets the required ground subsidence for the building, the remaining n-1 layers will not be filled. Otherwise, proceed to the next step.

[0020] ③ Simulate the dense filling of the first and second layers of the goaf, and do not fill the remaining n-2 layers, calculate the residual deformation of the surface, and so on, until the calculated sinking of any point within the horizontal treatment range of the building ground meets the surface deformation required by the house. Assume that the goaf is the nth layer. k layer, and calculate the maximum depth H that does not meet the conditions d , H d The maximum depth of filling required, the filling range of the foundation of the building is nth k All goafs above the goaf and the nth goaf k Part of the goaf area;

[0021] ④Determine the nth k The filling range of the goaf is x, which is the length of the projection of the maximum buried depth on the ground from the boundary of the horizontal treatment range, h is the thickness of the topsoil layer, is the topsoil movement angle, β is the bedrock movement angle, α is the coal seam inclination, H d is the maximum filling depth, then the nth k The shallowest depth H that the goaf needs to be filled a for

[0022]

[0023] According to the nth k The shallowest depth H that the goaf needs to be filled a , combined with the maximum filling depth H d Determine the nth k Filling range of the goaf;

[0024] ⑤ Use filling materials to fill the foundation filling range of the planned building structure;

[0025] Step 4: Construct buildings and heat pump system:

[0026] A structure is constructed on the surface above the goaf after filling is completed, and a heat pump system is constructed. The heat pump system includes an evaporator, a compressor, a condenser and an expansion valve which are connected end to end in a closed circulation system. A circulating refrigerant is provided inside the closed circulation system, and the evaporator is provided with a heat exchange chamber. Vertical drilling is performed from the surface to the goaf to form multiple pairs of production wells and reinjection wells, and the distance D between each pair of production wells and reinjection wells is greater than the thermal interference radius. A water pumping pipe is inserted into the production well, and an insulation layer is provided on the outside of the water pumping pipe. A water injection pipe is inserted into the reinjection well. A raw water filtering device is provided inside the water pumping pipe or at the bottom of the water pumping pipe. The water pumping pipe is connected to the raw water input end of the heat exchange chamber of the evaporator through a water pump and a control valve, and the return water output end of the heat exchange chamber of the evaporator is connected to the corresponding water injection pipe through a control valve.

[0027] While surface construction is underway, geophysical surveys and calculations are conducted in the goaf.

[0028] ① The impact range below the proposed building structure is n k Unfilled area of ​​goaf and n k Conduct geophysical surveys on all goafs below the goaf to obtain the spatial structure and collapse of the goaf, and determine the n k Layer goaf and n k The location distribution of aquifers near all goafs below the goaf;

[0029] ②Determine n k Layer goaf and n k The thickness of the water-conducting fracture zone in all goafs below the layer goaf is m, k is the rock looseness coefficient, α is the inclination angle of the ore layer, h1 is the thickness of the caving zone, and The thickness of the water-conducting fracture zone h2 is:

[0030] h2=(1~3)h1m;

[0031] Taking the vertical distance between the aquifer and the goaf as h0, if h2≥h0, there is underground raw water in the goaf; if h2<h0, the storage of groundwater in the goaf should be determined by geophysical survey first, and the goaf with little or no groundwater should be replenished with water through injection pipes to fill it with water;

[0032] Step 5: Heat:

[0033] For goafs with underground raw water, the control valves of the corresponding water extraction and injection pipes are opened and the water extraction pump and compressor are started. The raw water in the goaf is filtered by the raw water filter device and then enters the heat exchange chamber of the evaporator. The evaporator absorbs the heat of the raw water to convert the liquid refrigerant into gaseous refrigerant. The gaseous refrigerant enters the condenser under the action of the compressor. The condenser releases heat in the process of condensing the gaseous refrigerant into liquid refrigerant, which is used for heating surface buildings. The raw water after absorbing the heat is recharged into the underground goaf through the injection pipe.

[0034] For the goaf that needs water replenishment, after the set time, the control valves of the corresponding water extraction pipe and water injection pipe are opened and the water pump and compressor are started. The water replenished in the goaf enters the heat exchange chamber of the evaporator for heat exchange and is then re-injected into the underground goaf through the water injection pipe.

[0035] As a further improvement of the present invention, in step 4, the heat pump system further includes a purification device disposed between a return water output end of the heat exchange chamber of the evaporator and the water injection pipe, the purification device including a purification input end, a purifier addition device, and a purification output end disposed in sequence, the return water output end of the heat exchange chamber of the evaporator being connected to the purification input end of the purification device via a control valve, and the purification output end of the purification device being connected to the corresponding water injection pipe;

[0036] Prior to step 5, the process also includes testing the quality of raw water in the goaf where underground raw water exists. The process involves starting a water pump, extracting raw water samples from the heat exchange chamber of the evaporator for testing, determining the content of pollutants in the raw water, testing and determining the type and type of purifier, calculating the amount of purifier to be used based on the data on the extent of the abandoned mine goaf, and preparing the purifier.

[0037] In step five, for the goaf where underground raw water exists, the prepared purifier is added into the water injection pipe through the purifier adding device.

[0038] As a further improvement of the present invention, in step three, the production well and the recharge well are respectively drilled at the arc-shaped triangular plate fracture structure position at the top edge of the goaf.

[0039] As a further improvement of the present invention, h is the basic top thickness, R t is the tensile strength, q is the load, L1 is the basic top cycle pressure step, then m is the coal seam mining thickness, φ is the internal friction angle, c is the cohesion, A is the lateral pressure coefficient of the narrow coal pillar, k is the stress concentration coefficient, p ... cohesion, A is the cohesion, k is the stress concentration coefficient, p is the internal friction angle, c is the cohesion, x is the anchor support resistance of the coal side of the gob-side roadway, then

[0040]

[0041]

[0042] L0 is the distance between the block fracture position and the coal wall, and L2 is the span of the arc-shaped triangular block along the lateral fracture.

[0043] Then, the width dimension of the arc-shaped triangular plate at the fracture structure position is L2-L0.

[0044] As a further improvement of the present invention, in step 4, the distance D between the production well and the reinjection well is 50 to 80 m.

[0045] As a further improvement of the present invention, in step four, an anti-adhesion coating is provided on the inner surface of the water extraction pipe and the heat exchange chamber of the evaporator.

[0046] As a further improvement of the present invention, in step four, the purification output end of the purification device is connected to the water injection pipe through a water injection pump.

[0047] As a further improvement of the present invention, in step three, the surface of the particles of the filling material is coated with resin or wrapped with resin.

[0048] The technical effect of the present invention is as follows: compared with the existing technology, the method for the coordinated disposal of the foundation of the building structure in the old goaf and the deep space determines the foundation treatment depth according to the type, external dimensions and foundation design treatment grade requirements of the building structure to be built above the goaf of the abandoned mine, adopts the principle of shallow filling and deep utilization, builds surface buildings above the goaf of the abandoned mine, and constructs a heat pump system, utilizes the space structure formed after the collapse of the tunnel in the abandoned goaf, vertically drills from the surface to the goaf to form production wells and recharge wells, and channels the raw water flowing from the aquifer through the fracture zone in the goaf of the abandoned mine. The heat exchange of the superheat pump system can be used for heating surface buildings, and the raw water after absorbing heat is re-injected into the underground goaf, which can achieve "taking heat without taking water"; because it is equipped with a purification device, raw water samples can be extracted from the heat pump system for testing, and the pollutant content in the raw water can be determined. The amount of purifier is calculated and prepared according to the range data of the abandoned mine goaf, and the purifier is added to the water injection pipe through the purifier adding device. This can achieve the purification of the raw water in the abandoned mine goaf under the premise of "taking heat without taking water", thereby preventing the water resources in the abandoned mine goaf from damaging the ecological environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a structural schematic diagram of the present invention;

[0050] Figure 2 It is a schematic diagram of the principle of the present invention;

[0051] Figure 3 It is the specific structure of the arc-shaped triangular block of the abandoned mine

[0052] Figure 4 The buried depth of the present invention is greater than Hd Schematic diagram of the overhead structure of the deep goaf;

[0053] Figure 5 Schematic diagram of the structure of deep underground goaf and aquifer

[0054] Figure 6 Is to ensure that the burial depth is greater than H d Calculation diagram of the filling range of deep goaf

[0055] In the figure: 1. Water extraction pipe, 2. Water injection pipe, 3. Water extraction pump, 4. Water injection pump, 5. Heat pump system, 51. Evaporator, 52. Compressor, 53. Condenser, 54. Expansion valve, 6. Filling material, 7. Reserved coal pillar; I. ​​Aquifer, II. Bend zone, III. Fracture zone, IV. Caving zone. DETAILED DESCRIPTION

[0056] Groundwater is unaffected by solar radiation from the surface environment, so its temperature is primarily controlled by the ground temperature within which it lies. A narrow, thin section below 30 meters underground is in a constant-temperature zone, where the ground temperature remains largely constant year-round and is approximately 1-2°C higher than the region's annual average. Below this constant-temperature zone lies a warming zone, where the ground temperature rises by approximately 2°C for every 100 meters of depth. Generally, tunnel temperatures at a depth of 1,000 meters range from 35°C to 45°C, with some high-temperature areas exceeding 60°C to 70°C. The groundwater within abandoned mine goafs maintains a temperature roughly equivalent to that at this depth, making it suitable for use as a low-temperature heat source. The present invention utilizes this resource based on this principle.

[0057] The present invention will be further described below with reference to the accompanying drawings.

[0058] The method for coordinating the disposal of the foundation of buildings and structures in the old goaf and deep underground space specifically includes the following steps:

[0059] Step 1: Determine the current status of deep underground goaf: Collect geological maps of abandoned mines, mineral deposit distribution maps, mining engineering plans, and relevant surface deformation data.

[0060] Step 2: Determine the scope of foundation treatment for the structure to be built above the goaf:

[0061] ① Determine the ground treatment level according to the type of building to be constructed, and then determine the width d of the maintenance strip. s , the width of the maintenance zone is extended by the outline size of the proposed building structure s and the construction location determines the ground level treatment range;

[0062] ②Calculate the residual deformation of the ground:

[0063] With r as the main influencing radius, H as the mining depth, H0 as the average mining depth, and β as the main influencing angle,

[0064] θ is the maximum sinking angle, C is the sinking coefficient, l i is the calculated width of unit i, H i is the mining depth of unit i, then l i =H i ×C×tgθ;

[0065] (x i ,y i ) is the coordinate of the center point of unit i, then the amount of subsidence caused by unit i at any point on the ground (x, y) is

[0066]

[0067] P is the strike length of the working face, a is the horizontal distance of the working face along the inclined direction, if the goaf is a rectangle with the area of ​​0 to P and 0 to a, with W0 as the maximum subsidence value under the geological mining conditions, α as the inclination angle of the coal seam, q as the subsidence coefficient under full mining conditions, and m as the mining thickness of the coal seam, then W0 = mqcosα;

[0068] Then, the subsidence of any point on the ground surface above the goaf is

[0069]

[0070] Step 3: Goaf filling:

[0071] ① Assuming that there are n layers of underground space mined, none of which are filled, calculate the residual deformation of the ground surface. If the predicted subsidence of any point within the horizontal treatment range of the building ground meets the required surface deformation of the building, no filling is required. Otherwise, proceed to the next step.

[0072] ② Simulate dense filling of the shallowest first goaf, and leave the remaining n-1 layers unfilled. Calculate the residual deformation of the ground surface. If the predicted subsidence of any point within the horizontal treatment range of the building ground meets the required ground subsidence for the building, the remaining n-1 layers will not be filled. Otherwise, proceed to the next step.

[0073] ③ Simulate the dense filling of the first and second layers of the goaf, and do not fill the remaining n-2 layers, calculate the residual deformation of the surface, and so on, until the calculated sinking of any point within the horizontal treatment range of the building ground meets the surface deformation required by the house. Assume that the goaf is the nth layer. k layer, and calculate the maximum depth H that does not meet the conditions d , H d The maximum depth of filling required, the filling range of the foundation of the building is nth k All goafs above the goaf and the nth goaf k Part of the goaf area;

[0074] ④Determine the nth k Filling range of the goaf, such as Figure 6 As shown, x is the distance from the projection of the maximum buried depth on the ground to the boundary of the horizontal treatment range, h is the thickness of the topsoil layer, is the topsoil movement angle, β is the bedrock movement angle, α is the coal seam inclination, H d is the maximum filling depth, then the nth k The shallowest depth H that the goaf needs to be filled a for

[0075]

[0076] According to the nth k The shallowest depth H that the goaf needs to be filled a , combined with the maximum filling depth H d Determine the nth k Filling range of the goaf;

[0077] ⑤ Use filling material 6 to fill the foundation filling range of the planned building to ensure the stability of the foundation of the building. The filling material 6 can be natural sea sand or river sand with large particles, or artificial high-strength ceramic particles. Coating resin on the surface of natural sand particles or artificial high-strength ceramic particles can further improve the supporting strength and diversion performance.

[0078] Step 4: Constructing buildings and heat pump system 5:

[0079] like Figure 1 、 Figure 2As shown, a structure is constructed on the surface above the goaf after filling, and a heat pump system 5 is constructed. The heat pump system 5 includes an evaporator 51, a compressor 52, a condenser 53 and an expansion valve 54 which are connected end to end in a closed circulation system. A circulating refrigerant is provided inside the closed circulation system. The evaporator 51 is provided with a heat exchange chamber. The inner surface of the heat exchange chamber is provided with an anti-adhesion coating to prevent impurities from adhering. Vertical drilling is performed from the surface to the goaf to form multiple pairs of production wells and reinjection wells. In order to prevent the heat flow field caused by water circulation and the influence of cross flow that may cause The thermal imbalance of water resources in the abandoned mine goaf is solved. The distance D between each pair of production wells and recharging wells is greater than the thermal interference radius, preferably 50 to 80 meters. A pumping pipe 1 is placed in the production well, and an insulation layer is provided on the outside of the pumping pipe 1. An anti-adhesion coating is provided on the inner surface of the pumping pipe 1 to prevent impurities from adhering. A water injection pipe 2 is placed in the recharging well. A raw water filter device for filtering large particles of impurities such as coal rock and sludge in the raw water of the abandoned mine goaf is provided inside the pumping pipe 1 or at the bottom of the pumping pipe 1 to prevent pipe blockage. The pumping pipe 1 is connected to the evaporation pump 3 and the control valve. The raw water input end of the heat exchange chamber of the evaporator 51 is connected to the raw water input end, and the return water output end of the heat exchange chamber of the evaporator 51 is connected to the corresponding water injection pipe 2 through the control valve; the anti-adhesion coating can be made of a synthetic material including silicate, nanographite flakes, silicon carbide and the like, or a synthetic material including polyhedral oligomeric silsesquioxane, fluorine-modified organic silicone resin, inorganic adhesive and the like. Since the fluorine-modified organic silicone resin has excellent oleophobic and hydrophobic properties, and the inorganic core composed of a silicon-oxygen skeleton alternately connected by Si-O in the polyhedral oligomeric silsesquioxane can make the synthetic material The coating is denser, and the inorganic adhesive can enhance the bonding ability between the coating and the surface of the device and prevent it from falling off under long-term high-temperature conditions. Therefore, the latter is preferred. That is, the anti-adhesion coating is a synthetic material comprising polyhedral oligomeric silsesquioxane, fluorine-modified silicone resin and inorganic adhesive. The mass ratio of the inorganic adhesive, fluorine-modified silicone resin and polyhedral oligomeric silsesquioxane is 1: (6-8): (10-15). The anti-adhesion coating is evenly sprayed on the inner surface of the water extraction pipe 1 and the inner surface of the heat exchange chamber of the evaporator 51, with a spraying thickness of 50-100 μm.

[0080] While surface construction is underway, geophysical surveys and calculations of the mined-out areas are carried out, such as Figure 5 As shown in the figure, after coal seam mining, the overlying strata are destroyed and displaced, forming three zones: caving zone IV, fracture zone III, and bending zone II. Fracture zone III will gradually develop upward. When it connects with aquifer I overlying the coal seam, it will serve as a good water channel to transport the raw water of aquifer I to the goaf and roadway. Therefore, the thickness of fracture zone III is calculated to ensure that it can connect with aquifer I overlying the coal seam, providing water and heat sources for pumping water and heat extraction in the goaf.

[0081] ① The impact range below the proposed building structure is nk Unfilled area of ​​goaf and n k Conduct geophysical surveys on all goafs below the goaf to obtain the spatial structure and collapse of the goaf, and determine the n k Layer goaf and n k The location distribution of aquifers near all goafs below the goaf;

[0082] ②Determine n k Layer goaf and n k The thickness of the water-conducting fracture zone in all goafs below the coal seam goaf is m, k is the rock looseness coefficient, α is the coal seam inclination, h1 is the thickness of the caving zone, and The thickness of the water-conducting fracture zone h2 is:

[0083] h2=(1~3)h1m;

[0084] Taking the vertical distance between the aquifer and the goaf as h0, if h2≥h0, there is underground raw water in the goaf; if h2<h0, the storage situation of groundwater in the goaf is first determined by geophysical survey, and the goaf with little or no groundwater is replenished with water through the water injection pipe 2 to fill it with water.

[0085] Step 5: Heat:

[0086] For goafs with underground raw water, the control valves of the corresponding water extraction pipe 1 and water injection pipe 2 are opened, and the water extraction pump 3 and the compressor 52 are started. The raw water in the goaf is filtered by the raw water filter device and then enters the heat exchange chamber of the evaporator 51. The evaporator 51 absorbs the heat of the raw water to convert the liquid refrigerant into gaseous refrigerant. The gaseous refrigerant enters the condenser 53 under the action of the compressor 52. The condenser 53 releases heat in the process of condensing the gaseous refrigerant into liquid refrigerant, which is used for heating surface buildings. The raw water after absorbing the heat is recharged into the underground goaf through the water injection pipe 2, realizing "taking heat without taking water".

[0087] For the goaf that needs water replenishment, after the set time, the control valves of the corresponding water extraction pipe 1 and water injection pipe 2 are opened and the water pump 3 and compressor 52 are started. The water replenished in the goaf enters the heat exchange chamber of the evaporator 51 for heat exchange and is then re-injected into the underground goaf through the water injection pipe 2, realizing "taking heat without taking water".

[0088] In order to avoid the water resources in the abandoned mine goaf from damaging the ecological environment, as a further improvement scheme of the present invention, the heat pump system 5 also includes a purification device arranged between the return water output end of the heat exchange chamber of the evaporator 51 and the water injection pipe 2, the purification device includes a purification input end, a purifier adding device and a purification output end arranged in sequence, the return water output end of the heat exchange chamber of the evaporator 51 is connected to the purification input end of the purification device through a control valve, the purification output end of the purification device is connected to the corresponding water injection pipe 2, in order to reduce the pressure of the water pump 3, the purification output end of the purification device is connected to the water injection pipe 2 through the water injection pump 4; before the heat extraction step The method also includes the step of detecting the raw water quality in the goaf where underground raw water exists, that is, starting the water pump 3, extracting raw water samples in the heat exchange chamber of the evaporator 51 for testing, determining the pollutant content in the raw water, testing and determining the type and type of purifier, calculating the amount of purifier based on the range data of the abandoned mine goaf, and preparing the purifier; in the heat extraction step, for the goaf where underground raw water exists, the prepared purifier is added to the water injection pipe 2 through the purifier adding device, thereby realizing the purification of the raw water in the abandoned mine goaf under the premise of "extracting heat but not water", thereby preventing the water resources in the abandoned mine goaf from damaging the ecological environment.

[0089] According to the "Masonry Beam Theory", if Figure 3 、 Figure 4 As shown, a unique spatial structure is generated in the goaf after mining, the overlying rock layer collapses and forms an arc-shaped triangular block at the end of the working face, and the groundwater located in the goaf tends to flow along the continuous irregular arc-shaped triangular fracture structure. Therefore, in order to facilitate the smooth extraction or reinjection of groundwater resources located in the goaf through production wells or reinjection wells, as a further improvement scheme of the present invention, production wells and reinjection wells are respectively drilled at the arc-shaped triangular plate fracture structure position at the top edge of the goaf.

[0090] like Figure 3 As shown, h is the basic top thickness, R t is the tensile strength, q is the load, L1 is the basic top cycle pressure step, then m is the coal seam mining thickness, φ is the internal friction angle, c is the cohesion, A is the lateral pressure coefficient of the narrow coal pillar, k is the stress concentration coefficient, p ... cohesion, A is the cohesion, k is the stress concentration coefficient, p is the internal friction angle, c is the cohesion, x is the anchor support resistance of the coal side of the gob-side roadway, then

[0091]

[0092]

[0093] L0 is the distance between the block fracture position and the coal wall, and L2 is the span of the arc-shaped triangular block along the lateral fracture.

[0094] Then, the width dimension of the arc-shaped triangular plate at the fracture structure position is L2-L0.

[0095] This method of coordinated disposal of the foundations of structures in old goafs and deep underground space can realize the construction of buildings on the surface above the goafs of abandoned mines, avoid the waste of surface land resources, and use the raw water in the goafs of abandoned mines for heat exchange through a heat pump system for heating of surface buildings above the goafs. The raw water after absorbing heat is re-injected into the underground goaf through a purification device, and purifiers are added to the water injection pipes through a purifier adding device, which can purify the raw water in the goafs of abandoned mines under the premise of "taking heat but not water", thereby avoiding the water resources in the goafs of abandoned mines from damaging the ecological environment.

[0096] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Various changes that can be made within the scope of knowledge possessed by technicians in the relevant technical field without departing from the spirit of the present invention are all within the scope of protection of the claims of the present invention.

Claims

1. A method for coordinating the disposal of foundations of structures in old goaf areas and deep underground spaces, characterized in that: The specific steps include: Step 1: Determine the current status of deep underground goaf: Collect geological maps of abandoned mines, ore deposit distribution maps, mining engineering plan maps, and relevant surface deformation data; Step 2: Determine the scope of foundation treatment for the structure to be built above the goaf: ① Determine the ground treatment level according to the type of building to be constructed, and then determine the width d of the maintenance strip. s , the width of the maintenance zone is extended by the outline size of the proposed building structure s and the construction location determines the ground level treatment range; ②Calculate the residual deformation of the ground: With r as the main influencing radius, H as the mining depth, H0 as the average mining depth, and β as the main influencing angle, θ is the maximum sinking angle, C is the sinking coefficient, l i is the calculated width of unit i, H i is the mining depth of unit i, then l i =H i ×C×tgθ; (x i ,y i ) is the coordinate of the center point of unit i, then the amount of subsidence caused by unit i at any point on the ground (x, y) is P is the strike length of the working face, a is the horizontal distance of the working face along the inclined direction, if the goaf is a rectangle with the area of ​​0 to P and 0 to a, with W0 as the maximum subsidence value under the geological mining conditions, α as the inclination angle of the coal seam, q as the subsidence coefficient under full mining conditions, and m as the mining thickness of the coal seam, then W0 = mqcosα; Then, the subsidence of any point on the ground surface above the goaf is Step 3: Goaf filling: ① Assuming that there are n layers of underground space mined, none of which are filled, calculate the residual deformation of the ground surface. If the predicted subsidence of any point within the horizontal treatment range of the building ground meets the required surface deformation of the building, no filling is required. Otherwise, proceed to the next step. ② Simulate dense filling of the shallowest first goaf, and leave the remaining n-1 layers unfilled. Calculate the residual deformation of the ground surface. If the predicted subsidence of any point within the horizontal treatment range of the building ground meets the required ground subsidence for the building, the remaining n-1 layers will not be filled. Otherwise, proceed to the next step. ③ Simulate the dense filling of the first and second layers of the goaf, and do not fill the remaining n-2 layers, calculate the residual deformation of the surface, and so on, until the calculated sinking of any point within the horizontal treatment range of the building ground meets the surface deformation required by the house. Assume that the goaf is the nth layer. k layer, and calculate the maximum depth H that does not meet the conditions d , H d The maximum depth of filling required, the filling range of the foundation of the building is nth k All goafs above the goaf and the nth goaf k Part of the goaf area; ④Determine the nth k The filling range of the goaf is x, which is the length of the projection of the maximum buried depth on the ground from the boundary of the horizontal treatment range, h is the thickness of the topsoil layer, is the topsoil movement angle, β is the bedrock movement angle, α is the coal seam inclination, H d is the maximum filling depth, then the nth k The shallowest depth H that the goaf needs to be filled a for According to the nth k The shallowest depth H that the goaf needs to be filled a , combined with the maximum filling depth H d Determine the nth k Filling range of the goaf; ⑤ Use filling materials (6) to fill the determined foundation filling range of the proposed building structure; Step 4: Constructing buildings and heat pump systems (5): A structure is constructed on the surface above the goaf after filling, and a heat pump system (5) is constructed. The heat pump system (5) includes an evaporator (51), a compressor (52), a condenser (53) and an expansion valve (54) which are connected end to end in a closed circulation system. A circulating refrigerant is provided inside the closed circulation system, and the evaporator (51) is provided with a heat exchange chamber. Vertical drilling is performed from the surface to the goaf to form multiple pairs of production wells and reinjection wells, and the distance between each pair of production wells and reinjection wells is 1 / 4 of the total length. The distance D is greater than the thermal interference radius, a water pumping pipe (1) is inserted into the production well, a heat-insulating layer is provided on the outside of the water pumping pipe (1), an injection pipe (2) is inserted into the recharge well, a raw water filtering device is provided inside the water pumping pipe (1) or at the bottom of the water pumping pipe (1), the water pumping pipe (1) is connected to the raw water input end of the heat exchange chamber of the evaporator (51) through a water pump (3) and a control valve, and the return water output end of the heat exchange chamber of the evaporator (51) is connected to the corresponding injection pipe (2) through a control valve; While surface construction is underway, geophysical surveys and calculations are conducted in the goaf. ① The impact range below the proposed building structure is n k Unfilled area of ​​goaf and n k Conduct geophysical surveys on all goafs below the goaf to obtain the spatial structure and collapse of the goaf, and determine the n k Layer goaf and n k The location distribution of aquifers near all goafs below the goaf; ②Determine n k Layer goaf and n k The thickness of the water-conducting fracture zone in all goafs below the layer goaf is m, k is the rock looseness coefficient, α is the inclination angle of the ore layer, h1 is the thickness of the caving zone, and The thickness of the water-conducting fracture zone h2 is: h2=(1~3)h1m; The vertical distance between the aquifer and the goaf is h0. If h2≥h0, then there is underground raw water in the goaf. If h2<h0, the storage of underground water in the goaf is first determined by geophysical survey, and the goaf with little or no underground water is replenished with water through the water injection pipe (2) to fill it with water. Step 5: Heat: For a goaf with underground raw water, the control valves of the corresponding water extraction pipe (1) and water injection pipe (2) are opened, and then the water extraction pump (3) and the compressor (52) are started. The raw water in the goaf is filtered by the raw water filtering device and then enters the heat exchange chamber of the evaporator (51). The evaporator (51) absorbs the heat of the raw water to convert the liquid refrigerant into a gaseous refrigerant. The gaseous refrigerant enters the condenser (53) under the action of the compressor (52). The condenser (53) releases heat in the process of condensing the gaseous refrigerant into liquid refrigerant, and the released heat is used for heating surface buildings. The raw water after absorbing the heat is recharged into the underground goaf through the water injection pipe (2). For the goaf area to be replenished with water, after the set time, the control valves of the corresponding water extraction pipe (1) and water injection pipe (2) are opened and the water extraction pump (3) and the compressor (52) are started. The water replenished in the goaf enters the heat exchange chamber of the evaporator (51) for heat exchange and is then re-injected into the underground goaf through the water injection pipe (2).

2. The method for coordinating the disposal of foundations of structures in old goaf and deep underground space according to claim 1 is characterized in that: In step 4, the heat pump system (5) further includes a purification device arranged between the return water output end of the heat exchange chamber of the evaporator (51) and the water injection pipe (2), the purification device including a purification input end, a purification agent addition device and a purification output end arranged in sequence, the return water output end of the heat exchange chamber of the evaporator (51) is connected to the purification input end of the purification device through a control valve, and the purification output end of the purification device is connected to the corresponding water injection pipe (2); Before step 5, the method also includes a step of testing the quality of raw water in the goaf where underground raw water exists, starting the water pump (3), extracting raw water samples from the heat exchange chamber of the evaporator (51) for testing, determining the content of pollutants in the raw water, testing and determining the type and type of purifier, calculating the amount of purifier based on the range data of the abandoned mine goaf, and preparing the purifier; In step 5, for the goaf where underground raw water exists, the prepared purifier is added into the water injection pipe (2) through the purifier adding device.

3. A method for coordinating the disposal of foundations of structures in old goaf and deep underground space according to claim 1 or 2, characterized in that: In step three, the production well and the recharge well are respectively drilled at the arc-shaped triangular plate fracture structure position at the top edge of the goaf.

4. The method for coordinating the disposal of foundations of structures in old goaf and deep underground space according to claim 3 is characterized in that: Take h as the basic top thickness, R t is the tensile strength, q is the load, L1 is the basic top cycle pressure step, then m is the coal seam mining thickness, φ is the internal friction angle, c is the cohesion, A is the lateral pressure coefficient of the narrow coal pillar, k is the stress concentration coefficient, p ... cohesion, A is the cohesion, k is the stress concentration coefficient, p is the internal friction angle, c is the cohesion, x is the anchor support resistance of the coal side of the gob-side roadway, then L0 is the distance between the block fracture position and the coal wall, L2 is the span of the arc-shaped triangular block along the lateral fracture, Then, the width dimension of the arc-shaped triangular plate at the fracture structure position is L2-L0.

5. The method for coordinating the disposal of foundations of structures in old goaf and deep underground space according to claim 1 is characterized in that: In step 4, the distance D between the production well and the reinjection well is 50 to 80 m.

6. The method for coordinating the disposal of foundations of structures in old goaf areas and deep underground spaces according to claim 1 is characterized in that: In step 4, an anti-adhesion coating is provided on the inner surface of the water extraction pipe (1) and the heat exchange chamber of the evaporator (51).

7. A method for coordinating the disposal of foundations of structures in old goaf areas and deep underground spaces according to claim 1 or 2, characterized in that: In step 4, the purification output end of the purification device is connected to the water injection pipe (2) through the water injection pump (4).

8. A method for coordinating the disposal of foundations of structures in old goaf areas and deep underground spaces according to claim 1 or 2, characterized in that: In step three, the surface of the particles of the filling material (6) is coated with resin or wrapped with resin.

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