Backfilling and plugging of abandoned vertical shafts in thick loose layers and reconstruction of impermeable layers

Abstract

The present invention provides a method for backfilling and plugging abandoned vertical shafts in thick loose layers and reconstructing a water-blocking layer, comprising the following steps: step 1, determining the basic conditions of the abandoned vertical shaft and the stratum; step 2, plugging the entire abandoned vertical shaft, and sealing the abandoned vertical shaft from bottom to top; step 3, cutting and segmenting the abandoned vertical shaft, and cutting and segmenting the abandoned vertical shaft located above the bottom aquifer; step 4, grouting inside the abandoned vertical shaft and reconstructing the bottom aquifer and the bottom water-blocking layer by grouting; step 5, sealing the manhole cover of the abandoned vertical shaft. The method adopts the technology of backfilling and plugging the abandoned vertical shaft, grouting inside the abandoned vertical shaft, and grouting reinforcement of the bottom aquifer outside the abandoned vertical shaft, to reconstruct the bottom aquifer and the bottom water-blocking layer conducted by the abandoned vertical shaft into an integral stratum, avoid forming a water-conducting interface between the abandoned vertical shaft and the stratum, and ensure the safety of compressed coal mining in the abandoned vertical shaft.

Description

Technical Field

[0001] The invention relates to the field of abandoned mine treatment and coal resource mining, and in particular to a method for backfilling and plugging an abandoned vertical shaft with a thick loose layer and reconstructing an impermeable layer. Background Art

[0002] With the long-term high-intensity and large-scale mining of coal resources, the coal resources in some old mining areas are becoming exhausted, and a large number of coal mines are facing closure or have been closed. Under the condition that safety conditions permit, recycling the protective coal pillars of the shafts that are about to be scrapped can reduce resource waste and asset loss.

[0003] At present, when protecting the coal pillar in abandoned vertical shafts, the whole shaft is generally backfilled with waste rock to seal it, and then the wellhead is sealed with concrete. Under the condition of overlying water-rich thick loose layers and thin bedrock, the movement of overburden caused by compressed coal mining will lead to changes in the stress field between the abandoned shaft and the overlying strata, and there is a risk of triggering the drainage channel of the thick loose aquifer, water seepage along the abandoned shaft, and sudden water and sand disasters, threatening the safety of underground production. How to safely and effectively recover the coal resources under the abandoned shaft with overlying water-rich thick loose layers and thin bedrock has become a technical problem that needs to be solved urgently in many old mining areas waiting to be closed. At present, there is little research on the prevention and control of water hazards caused by compressed coal mining in abandoned shafts that trigger the drainage channel of the thick loose aquifer, making it difficult to ensure the safe recovery of coal resources covered by abandoned vertical shafts.

[0004] In response to the demand for utilization of abandoned vertical shaft covered coal resources, and given that there is currently no prevention and control technology to avoid the triggering of thick loose aquifer drainage channels and water seepage along the abandoned shaft by abandoned vertical shaft covered coal mining, a method for backfilling and sealing abandoned vertical shafts with thick loose layers and reconstructing impermeable layers is urgently needed to treat the abandoned vertical shafts and thick loose impermeable layers before abandoned vertical shaft covered coal mining. Summary of the invention

[0005] The purpose of the present invention is to provide a method for backfilling and sealing an abandoned vertical shaft with a thick loose layer and reconstructing an impermeable layer. The method backfills and seals the abandoned vertical shaft and reconstructs the bottom aquifer and bottom impermeable layer that are connected to the abandoned shaft into an integral stratum, thereby avoiding the formation of a water-conducting interface between the abandoned shaft and the stratum, thereby ensuring the safety of compressed coal mining in the abandoned shaft.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for backfilling and plugging abandoned vertical shafts with thick loose layers and reconstructing water-blocking layers comprises the following steps:

[0008] Step 1: determine the basic conditions of the abandoned shaft and strata, and determine the basic parameters of the abandoned shaft and strata based on the data of the abandoned shaft and on-site investigation;

[0009] Step 2: Fully seal the abandoned shaft. The abandoned shaft is fully sealed from bottom to top, and the horse head gate and the bottom section, the upper layer of the bedrock section of the coal-bearing stratum, the aquifer at the bottom of the thick loose layer, the aquiclude at the bottom of the thick loose layer, and the middle and upper part of the thick loose layer are sealed in sequence;

[0010] Step 3, cutting and segmenting the abandoned vertical shaft, cutting and segmenting the abandoned vertical shaft located above the bottom aquifer;

[0011] Step 4: Grouting inside the abandoned shaft and reconstructing the bottom aquifer and bottom aquiclude by grouting the inside of the abandoned shaft through vertical drilling on the construction ground, and grouting the bottom aquifer and bottom aquiclude outside the abandoned shaft through directional drilling on the construction ground;

[0012] Step 5, seal the manhole cover of the abandoned vertical shaft.

[0013] Furthermore, in the above-mentioned method for backfilling and plugging of abandoned vertical shafts with thick loose layers and reconstruction of impermeable layers, in step 1, the basic parameters of the abandoned vertical shaft and the formation include the inner diameter R1 and outer diameter R2 of the abandoned vertical shaft, the thickness M of the well wall, the depth H of the well shaft, the construction method of the abandoned vertical shaft, the stratification of the formation, the thickness of the thick loose layer, the thickness of the bottom aquifer and the thickness of the bottom impermeable layer.

[0014] Furthermore, in the above-mentioned method for backfilling and plugging abandoned vertical shafts in thick loose layers and reconstructing impermeable layers, in step 2, the following steps are included:

[0015] Step 21, seal the horse head gate and the bottom section, construct a closed wall on each side of the horizontal lane of the horse head gate at the bottom of the abandoned vertical shaft, the closed wall is made of C30 reinforced concrete, the outer edge of the closed wall is connected to the inner wall of the horizontal lane, the thickness of the closed wall is 1m~2m, the bottom of the abandoned vertical shaft and the space between the two closed walls are filled with large pieces of waste, the particle size of the large pieces of waste is 25cm~60cm, the large pieces of waste are filled to the upper elevation h1 of the horse head gate, h1=5m~10m, and concrete is pumped into the gaps of the large pieces of waste;

[0016] Step 22, plugging the upper layer of the bedrock section of the coal-bearing stratum, covering the top surface of the large piece of waste material and concrete at the upper elevation h1 of the horse head gate with a waterproofing membrane, filling the abandoned vertical shaft above the waterproofing membrane with a mixed filler, the mixed filler is a mixture of material and fly ash, the material is gangue, waste rock or tailings, and the mixed filler of material and fly ash is filled to the elevation h2 below the lower interface of the thick loose layer, h2=5m~10m, and the mass ratio of material to fly ash is 10:1~20:1;

[0017] Step 23, plugging the bottom aquifer of the thick loose layer, laying a waterproofing roll on the top surface of the mixed filler of material and fly ash at h2 below the lower interface of the thick loose layer, filling the mixed filler of material and cement on the waterproofing roll, and filling the mixed filler of material and cement to the upper elevation h3 of the top surface of the bottom aquifer, h3=5m~10m, and the mass ratio of material to cement is 5:1~10:1;

[0018] Step 24, seal the bottom waterproof layer of the thick loose layer, lay a waterproof roll on the top of the mixed filler of material and cement at the upper elevation h3 of the top surface of the bottom aquifer, fill the waterproof roll with cooked loess and tamp it, and fill the cooked loess to the top surface of the bottom waterproof layer;

[0019] Step 25, seal the middle and upper part of the thick loose layer, lay waterproof membrane on the cooked loess on the top surface of the bottom waterproof layer, alternately fill the waterproof membrane with mixed filler mixed with materials and fly ash and cooked loess, lay waterproof membrane between the mixed filler and the cooked loess, the top layer of filling material in the abandoned vertical shaft in the middle and upper part of the thick loose layer is cooked loess, the filling thickness H1 of each layer of mixed filler in the thick loose layer is 20m~50m, the filling thickness H2 of each layer of cooked loess is 5m~10m, and the distance between the top surface of the top layer of cooked loess and the wellhead is 2m~3m.

[0020] Furthermore, in the above-mentioned method for backfilling and plugging abandoned vertical shafts in thick loose layers and reconstructing aquicludes, in step 23, before plugging the bottom aquifer of the thick loose layer, firstly, the shaft wall of the abandoned vertical shaft corresponding to the bottom aquifer is reinforced and supported to form a reinforced support system; the reinforced support system includes grouting anchor rods, channel steel well rings and vertical I-beams, one end of the grouting anchor rods is located on the inner side of the shaft wall of the abandoned vertical shaft, the other end of the grouting anchor rods is located in the stratum outside the abandoned vertical shaft, and the grouting anchor rods are evenly arranged with N along the axial direction of the abandoned vertical shaft. Layers, N=4~8, 8 grouting anchor rods are evenly arranged in each layer along the circumference of the abandoned vertical shaft; one end of the grouting anchor rod in the topmost layer is located 2m~3m below the upper edge of the well wall of the bottom aquifer section, the axis of the grouting anchor rod in the topmost layer has an upward inclination angle of 10°~20°, and the other end of the grouting anchor rod in the topmost layer extends to 2m~3m inside the bottom aquifer; one end of the grouting anchor rod in the bottom layer is located 2m~3m above the lower edge of the well wall of the bottom aquifer section, the axis of the grouting anchor rod in the bottom layer has an upward inclination angle of 10°~20° The other end of the grouting anchor rod in the lowest layer extends to 2m~3m in the coal-bearing bedrock layer at a downward inclination angle; the axes of the grouting anchor rods in other layers except the top and bottom layers are perpendicular to the shaft wall of the abandoned vertical shaft; the grouting anchor rods in the top layer and the grouting anchor rods in the lowest layer are arranged symmetrically, and the grouting anchor rods in the remaining layers are arranged in a staggered manner, and the vertical layer spacing of one end of the grouting anchor rods in two adjacent layers is 2~3m; the channel steel shaft ring is a circular structure, and the channel steel shaft ring is horizontally arranged on the inner wall of the abandoned vertical shaft, and the outer diameter of the channel steel shaft ring is the same as that of the abandoned vertical shaft The inner diameter of the cylinder is consistent, and there are multiple channel steel well rings. Each layer of the grouting anchor is provided with a channel steel well ring, and the channel steel well ring is arranged below one end of the grouting anchor, and the channel steel well ring is connected to the grouting anchor in the corresponding layer; the vertical I-beam is vertically arranged on the inner wall of the abandoned vertical shaft, and the length of the vertical I-beam is consistent with the thickness of the bottom aquifer section, and the vertical I-beam is connected to multiple channel steel well rings. There are 4 or 8 vertical I-beams, and the multiple vertical I-beams are evenly arranged along the circumference of the abandoned vertical shaft.

[0021] Furthermore, in the above-mentioned method for backfilling and plugging abandoned vertical shafts in thick loose layers and reconstructing aquicludes, in step 2, in the process of plugging the entire abandoned vertical shaft, a layer of drilled holes is constructed on the inner wall of the abandoned vertical shaft at h2 below the lower interface of the bottom aquifer, a layer of drilled holes is constructed on the inner wall of the abandoned vertical shaft at an elevation h3 on the upper part of the top surface of the bottom aquifer, a layer of drilled holes is constructed on the inner wall of the abandoned vertical shaft at the top surface of the bottom aquiclude, and a layer of drilled holes is constructed vertically every 100m on the inner wall of the abandoned vertical shaft above the bottom aquiclude. The number of drilled holes in each layer is 8 to 16, and each layer The multiple boreholes are evenly distributed along the circumference of the abandoned vertical shaft, and the depth of the boreholes is 4 / 5 of the thickness of the wall of the abandoned vertical shaft; filling expansion agent or explosives in each of the boreholes, and after filling the expansion agent or explosives, the boreholes are sealed with cement mortar, and the detonating fuse of the expansion agent or explosive is led out of the ground through a steel pipe; in the step 3, by detonating the expansion agent or explosive pre-buried in the borehole in the step 2, the abandoned vertical shaft at h2 below the lower interface of the bottom aquifer, at the upper elevation h3 of the top surface of the bottom aquifer, and at the top surface of the bottom aquifer and above the bottom aquiclude are cut and segmented.

[0022] Furthermore, in the above-mentioned method for backfilling and plugging abandoned vertical shafts in thick loose layers and reconstructing aquicludes, in step 4, the ground vertical borehole is arranged at the axis of the abandoned vertical shaft, and the lower end of the ground vertical borehole is located (h2-2) m below the lower interface of the bottom aquifer, and a number of grouting holes are evenly distributed on the side wall of the ground vertical borehole located in the bottom aquifer, and the mixed filler of gangue and cement implemented in step 23 is grouting reinforced; before grouting through the ground vertical borehole, it is necessary to first conduct groundwater observation of the layer to be grouting in the abandoned vertical shaft to determine the hydrostatic pressure of the groundwater p a The ground vertical drilling grouting pressure is the hydrostatic pressure of groundwater. p a 1.5~2.0 times of.

[0023] Furthermore, in the above-mentioned method for backfilling and plugging abandoned shafts in thick loose layers and reconstructing aquicludes, in step 4, the ground directional drilling is used to perform grouting reinforcement on the strata in the area between (h2-2) m below the lower interface of the bottom aquifer outside the abandoned shaft and the upper elevation h3 of the top surface of the bottom aquifer; before grouting through the ground directional drilling, it is necessary to first conduct groundwater observation of the layer to be grouted outside the abandoned shaft to determine the hydrostatic pressure of the groundwater in the layer to be grouted p b The grouting pressure of the ground directional drilling is the hydrostatic pressure of the groundwater at the grouting layer. p b 2.0~2.5 times of.

[0024] Furthermore, in the above-mentioned method for backfilling and plugging abandoned vertical shafts in thick loose layers and reconstructing aquicludes, in step 4, the ground directional drilling includes an upper straight hole section, an inclined hole section and a lower straight hole section, the axis of the upper straight hole section and the axis of the lower straight hole section are both parallel to the axis of the abandoned vertical shaft, the lower end of the upper straight hole section is located above the bottom aquiclude, the upper end of the lower straight hole section is located above the bottom aquifer, the lower end of the lower straight hole section is located below the bottom aquifer, and the two ends of the inclined hole section are respectively The upper straight hole section and the lower straight hole section are respectively connected; 8 to 10 ground directional drilling holes are arranged, and all the layout points of the ground directional drilling holes on the ground are located on a circle with the center of the abandoned vertical shaft as the center and a radius of R3, R3=10m~20m, the hole spacing of the layout points of the ground directional drilling holes on the ground is 10m~15m, and the distance between the axis of the lower straight hole section and the outer wall of the abandoned vertical shaft is R3 / 2; a number of grouting holes are evenly distributed on the side wall of the lower straight hole section.

[0025] Furthermore, in the above-mentioned method for backfilling and plugging an abandoned vertical shaft in a thick loose layer and reconstructing an aquiclude, in step 4, the ground directional drilling includes a vertical section, an inclined section and a horizontal section, the lower end of the vertical section is located above the bottom aquiclude, the horizontal section is located in the bottom aquifer, the axis of the horizontal section is perpendicular to the wall of the abandoned vertical shaft, and the end point of the ground directional drilling is 2m~4m away from the outer wall of the abandoned vertical shaft; the ground directional drilling includes 4 hole groups, the 4 hole groups are evenly distributed along the circumference of the abandoned vertical shaft, each hole group includes 4 ground directional drilled holes, the centers of the 4 arrangement points on the ground in one hole group are all located on the extension line of a radius of the abandoned vertical shaft, and on the same On a cross section, the corresponding arrangement points of the four hole groups are located on the same circumference with the center of the abandoned vertical shaft, and the distance R4 between the center of the arrangement point of the ground directional drilling and the center of the abandoned vertical shaft is 30m~40m; the end points of the four ground directional drilling holes in a hole group are all located in the bottom aquifer, and the end points of the four ground directional drilling holes in a hole group are arranged in sequence from top to bottom. Relative to the height of the bottom aquifer, the end points of the four ground directional drilling holes in a hole group are respectively located at 1 / 8, 3 / 8, 5 / 8 and 7 / 8 of the bottom aquifer, and the center of the end points of the four ground directional drilling holes in a hole group and the center of the arrangement point are located on the same vertical section.

[0026] Furthermore, in the above-mentioned method for backfilling and plugging abandoned vertical shafts in thick loose layers and reconstructing impermeable layers, in step 5, the following steps are specifically included:

[0027] Step 51, excavating an annular manhole cover pit, excavating an annular manhole cover pit with a width of 2m~3m and a depth of d along the outer edge of the abandoned vertical shaft;

[0028] Step 52, laying manhole cover grates, using I-beams to set up manhole cover grates at the wellhead of the abandoned vertical shaft, wherein the manhole cover grates are set up horizontally and vertically using I22b I-beams, and the spacing between the I-beams is 0.5m;

[0029] Step 53, pouring manhole cover concrete, pouring concrete into the annular manhole cover pit and the abandoned vertical shaft, the concrete model is C30, and the concrete thickness is (d+1)m~(d+2)m;

[0030] The manhole cover grate extends into the concrete in the annular manhole cover pit by no less than 0.3m;

[0031] The outer edge of the manhole cover grate is located in the middle between the outer wall and the inner wall of the annular manhole cover pit;

[0032] In step 5, according to actual needs, the well wall of the abandoned vertical shaft at a depth of 1m~2m is cut so that the laid manhole cover grate is located below the ground, and the upper surface of the concrete poured in the annular manhole cover pit is controlled to be flush with the ground surface.

[0033] It can be seen from the analysis that the present invention discloses a method for backfilling and plugging abandoned shafts with thick loose layers and reconstructing aquicludes. Starting from the interaction between abandoned shafts and thick loose layers under abandoned shaft coal mining, before abandoned shaft coal mining, this method uses abandoned shaft shaft backfilling and plugging, abandoned shaft shaft internal grouting, and abandoned shaft shaft external bottom aquifer grouting reinforcement technology to reconstruct the bottom aquifer and bottom aquiclude that are connected to the abandoned shaft shaft into an integral stratum, avoiding the formation of a water-conducting interface between the abandoned shaft shaft and the stratum, and ensuring the safety of abandoned shaft coal mining. This method fills the gap in the current prevention and control technology of the water-conducting channel triggered by abandoned shaft coal mining in thick loose layers and water seepage along the abandoned shaft, and provides a technical reference for the subsequent recovery of the protective coal pillars of the shafts that are about to be scrapped. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0035] Figure 1 The present invention is a flowchart of a method for backfilling and plugging an abandoned shaft and reconstructing an impermeable layer according to an embodiment of the present invention.

[0036] Figure 2 This is a schematic diagram of backfilling and plugging of an abandoned vertical shaft according to an embodiment of the present invention.

[0037] Figure 3 It is a schematic structural diagram of a reinforcement support system according to an embodiment of the present invention.

[0038] Figure 4 It is a schematic top view of a reinforcement support system according to an embodiment of the present invention.

[0039] Figure 5 This is a schematic diagram of drilling a hole in the wall of an abandoned vertical shaft and filling it with an expansion agent or explosive according to an embodiment of the present invention.

[0040] Figure 6 It is a schematic diagram of implementing ground vertical drilling and ground directional drilling according to an embodiment of the present invention.

[0041] Figure 7 It is a schematic diagram of implementing ground vertical drilling and ground directional drilling according to another embodiment of the present invention.

[0042] Figure 8 for Figure 7 Schematic top view of .

[0043] Fig. 9 A schematic diagram of closing a manhole cover of an abandoned vertical shaft according to an embodiment of the present invention.

[0044] Fig.10 This is a schematic diagram of the closure of a manhole cover after the wellhead of an abandoned vertical shaft is cut according to an embodiment of the present invention.

[0045] Fig.11 It is a top view schematic diagram of the closure of the manhole cover of an abandoned vertical shaft according to one embodiment of the present invention.

[0046] Explanation of the reference numerals in the accompanying drawings: 1 abandoned shaft; 2 horse head gate; 3 closed wall; 4 bedrock section of coal-bearing strata; 5 thick loose layer; 6 bottom aquifer; 7 bottom impermeable layer; 8 manhole cover grate; 9 fence; 10 middle and upper aquifer and impermeable layer; 11 grouting anchor rod; 12 channel steel well ring; 13 vertical I-beam rail; 14 expansion agent or explosive; 15 cement mortar; 16 steel pipe; 17 ground vertical drill; 18 ground directional drilling; 19 upper straight hole section; 20 inclined hole section; 21 lower straight hole section; 22 grouting hole; 23 vertical section; 24 inclined section; 25 horizontal section; 26 annular manhole cover pit. DETAILED DESCRIPTION

[0047] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments. Each example is provided by way of explanation of the present invention and does not limit the present invention. In fact, it will be clear to those skilled in the art that modifications and variations may be made in the present invention without departing from the scope or spirit of the present invention. For example, a feature shown or described as a part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desired that the present invention encompasses such modifications and variations within the scope of the appended claims and their equivalents.

[0048] In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention. The terms "connected", "connected" and "set" used in the present invention should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be a direct connection or an indirect connection through an intermediate component; it can be a wired electrical connection, a radio connection, or a wireless communication signal connection. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0049] One or more examples of the present invention are shown in the accompanying drawings. The detailed description uses numbers and letter labels to refer to features in the drawings. Like or similar labels in the drawings and description have been used to refer to like or similar parts of the present invention. As used herein, the terms "first", "second", "third", etc. are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of individual components.

[0050] like Figures 1 to 11 As shown, according to an embodiment of the present invention, a method for backfilling and sealing an abandoned vertical shaft in a thick loose layer and reconstructing an aquiclude is provided. The aquiclude in the name of the invention refers to a combination of strata with different water-proof properties in a geological structure, namely, aquifers and aquicludes. Generally, there are multiple aquifers and aquicludes in a thick loose layer, the lowest aquifer is the bottom aquifer, and the lowest aquiclude is the bottom aquiclude. This method adopts backfilling and sealing of the abandoned vertical shaft, grouting inside the abandoned vertical shaft, and grouting of the bottom aquifer outside the abandoned vertical shaft to reconstruct the bottom aquifer 6 and the bottom aquiclude 7 that are connected to the abandoned vertical shaft 1 into an integral stratum, thereby avoiding the formation of a water-conducting interface between the abandoned vertical shaft 1 and the stratum. Figure 1 As shown, the method comprises the following steps:

[0051] Step 1: Determine the basic conditions of the abandoned vertical shaft and strata.

[0052] Based on the data of the abandoned vertical shaft 1 and combined with on-site investigation, the basic parameters of the abandoned vertical shaft and the stratum are determined, and the basic parameters of the abandoned vertical shaft and the stratum include the inner diameter R1 and outer diameter R2 of the abandoned vertical shaft 1, the thickness M of the shaft wall, the depth H of the shaft, the construction method of the abandoned vertical shaft, the stratification of the stratum, the thickness of the thick loose layer 5, the thickness of the bottom aquifer 6 and the thickness of the bottom impermeable layer 7, etc.

[0053] The on-site investigation can be carried out by combining geophysical exploration and drilling verification. The geophysical exploration method can use seismic wave method and electromagnetic method to determine the integrity of the abandoned vertical shaft 1 and the structure of the surrounding strata. According to the geophysical exploration results or preliminary judgment, drilling is carried out at appropriate locations around the shaft to obtain core samples and visually observe the characteristics of the stratum rock, including rock type, particle size, cementation degree, etc. At the same time, monitoring equipment can also be installed in the borehole, such as water level gauges to determine the water level of the aquifer, and pressure gauges to measure the formation pressure, etc. These data are very important for understanding the hydrogeological conditions and mechanical state of the stratum.

[0054] Step 2: The abandoned shaft is completely sealed. Figure 2 As shown, the abandoned vertical shaft 1 is completely sealed from bottom to top, and the horse head gate 2 and the bottom section of the shaft, the upper layer of the bedrock section of the coal-bearing stratum, the aquifer at the bottom of the thick loose layer, the impermeable layer at the bottom of the thick loose layer, and the middle and upper part of the thick loose layer are sealed in sequence, which specifically includes the following steps:

[0055] Step 21, seal the horse head gate and the bottom section of the shaft, and construct a closed wall 3 on both sides of the horse head gate 2 at the bottom of the abandoned shaft 1. The closed wall 3 is made of C30 reinforced concrete, and the outer edge of the closed wall 3 is connected to the inner wall of the horizontal lane. The thickness of the closed wall 3 is 1m~2m. In order to ensure the stability of the overall structure of the horse head gate 2 and avoid water seepage at the bottom of the shaft, large pieces of waste are filled at the bottom of the abandoned shaft 1 and the space between the two closed walls 3. The particle size of the large pieces of waste is 25cm~60cm. The large pieces of waste are filled to the upper elevation h1 of the horse head gate 2, h1=5m~10m, and concrete is pumped into the gaps of the large pieces of waste. If the depth of the area to be filled is greater than 400m, in order to ensure the filling effect and prevent the large pieces of waste from excessive rolling or displacement during the filling process, large pieces of waste with a particle size of 40cm~60cm are used. The large pieces of waste can support each other after filling, thereby improving the stability of the closed structure.

[0056] Step 22, seal the upper layer of the bedrock section of the coal-bearing stratum, cover the waterproof membrane on the top surface of the large piece of waste and concrete at the upper elevation h1 of the horse head gate 2, and fill the mixed filler above the waterproof membrane. The mixed filler of the upper layer of the bedrock section 4 of the coal-bearing stratum is a mixture of materials and fly ash. The materials are taken on site and waste is utilized. The materials can be gangue, waste rock or tailings, etc. The mixed filler of materials and fly ash is filled to the lower interface of the thick loose layer 5 (i.e., the lower interface of the bottom aquifer 6) at an elevation h2, h2=5m~10m, and the mass ratio of materials to fly ash is 10:1~20:1.

[0057] Step 23, seal the bottom aquifer of the thick loose layer, lay a waterproof membrane on the top surface of the mixed filler of material and fly ash at h2 below the lower interface of the thick loose layer 5 (i.e., the lower interface of the bottom aquifer 6), fill the waterproof membrane with a mixed filler of material and cement, and fill the mixed filler of material and cement to the upper elevation h3 of the top surface of the bottom aquifer 6, h3=5m~10m, and the mass ratio of material to cement is 5:1~10:1.

[0058] Before sealing the bottom aquifer of the thick loose layer, the well wall of the abandoned vertical shaft 1 corresponding to the bottom aquifer 6 is first reinforced and supported to form a reinforced support system to avoid the abandoned vertical shaft 1 and the formation settling asynchronously during subsequent coal seam mining, resulting in the well wall of the abandoned vertical shaft 1 in the bottom aquifer 6 breaking, thereby increasing the formation of a downward water diversion channel at the bottom aquifer 6 and water seepage along the abandoned vertical shaft 1, thereby causing the risk of sudden water and sand gushing and causing disasters, threatening underground production safety.

[0059] like Figure 3 and Figure 4As shown, the reinforcement support system includes a grouting anchor rod 11, a channel steel well ring 12 and a vertical I-beam 13, one end of the grouting anchor rod 11 is located on the inner side of the shaft wall of the abandoned vertical shaft 1, and the other end of the grouting anchor rod 11 is located in the stratum outside the abandoned vertical shaft 1. The grouting anchor rod 11 is evenly arranged in N layers along the axial direction of the abandoned vertical shaft 1, N=4~8, from top to bottom are 1, 2, 3...N layers of grouting anchor rods 11, and each layer has 8 grouting anchor rods 11 evenly arranged along the circumference of the abandoned vertical shaft 1; one end of the grouting anchor rod 11 in the topmost layer (the first layer) is located 2m~3m below the upper edge of the shaft wall of the bottom aquifer section, the axis of the grouting anchor rod 11 in the topmost layer has an upward inclination angle of 10°~20°, and the other end of the grouting anchor rod 11 in the topmost layer extends to 2m~3m inside the bottom waterproof layer 7. One end of the grouting anchor rod 11 in the bottom layer (Nth layer) is located 2m~3m above the lower edge of the well wall of the bottom aquifer section, the axis of the grouting anchor rod 11 in the bottom layer has a downward inclination angle of 10°~20°, and the other end of the grouting anchor rod 11 in the bottom layer extends to 2m~3m in the coal-bearing bedrock layer; except for the top layer and the bottom layer, the axis of the grouting anchor rod 11 in other layers (2nd to N-1th layers) is perpendicular to the well wall of the abandoned vertical shaft 1. The grouting anchor rods 11 in the top layer are arranged symmetrically with the grouting anchor rods 11 in the bottom layer, and the grouting anchor rods 11 in the other layers are arranged alternately. The vertical layer spacing of one end of the two adjacent layers of grouting anchor rods 11 is 2m~3m, and the layer spacing of the grouting anchor rods 11 is reasonably adjusted according to the inner diameter size of the abandoned vertical shaft 1, the stability of the well wall, the stability of the surrounding rock, etc., to ensure the stability of the abandoned vertical shaft 1 and the safety of subsequent construction.

[0060] The channel steel well ring 12 is a circular structure. The channel steel well ring 12 is horizontally arranged on the inner wall of the abandoned vertical shaft 1. The outer diameter of the channel steel well ring 12 is consistent with the inner diameter of the abandoned vertical shaft 1. There are multiple channel steel well rings 12, and each layer of grouting anchor rods 11 is provided with a channel steel well ring 12. The channel steel well ring 12 is arranged below one end of the grouting anchor rods 11. The channel steel well ring 12 and the grouting anchor rods 11 in the corresponding layer are connected by welding or bolts.

[0061] A vertical I-beam 13 is vertically arranged on the inner wall of the abandoned vertical shaft 1. The length of the vertical I-beam 13 is consistent with the thickness of the bottom aquifer section. The vertical I-beam 13 is connected to multiple channel steel rings 12 by welding or bolts. There are 4 or 8 vertical I-beams 13, and the multiple vertical I-beams 13 are evenly arranged along the circumference of the abandoned vertical shaft 1.

[0062] Step 24, seal the bottom waterproof layer of the thick loose layer, and cover the top surface of the mixed filler of material and cement at the upper elevation h3 of the top surface of the bottom aquifer 6 with waterproof membrane, fill the waterproof membrane with cooked loess and tamp it, fill the cooked loess to the top surface of the bottom waterproof layer 7, and cover the top surface of the cooked loess with waterproof membrane.

[0063] The cooked loess used in the present invention is specially treated loess, such as by exposure to the sun, baking, adding water to moisten the loess, etc. After the treatment, the soil particles of the cooked loess will shrink to a certain extent, the gaps will be reduced, the structure will become relatively tight, and the plasticity will be enhanced. According to the actual engineering situation, Sanqi lime soil can also be used instead of cooked loess to fill the abandoned vertical shaft 1 to improve the compressive strength and anti-seepage ability.

[0064] Step 25, plug the middle and upper part of the thick loose layer, lay waterproofing rolls on the cooked loess on the top surface of the bottom waterproof layer 7, alternately fill the abandoned vertical shaft 1 in the middle and upper part of the thick loose layer (the middle and upper aquifer and the waterproof layer 10) above the waterproofing rolls with mixed fillers mixed with materials and fly ash and cooked loess, lay waterproofing rolls between the mixed fillers and the cooked loess, and the top layer of filler in the abandoned vertical shaft in the middle and upper part of the thick loose layer is cooked loess, and each layer of cooked loess needs to be compacted after filling. The filling thickness H1 of each layer of mixed filler in the thick loose layer 5 is 20m~50m, and the filling thickness H2 of each layer of cooked loess is 5m~10m. The distance between the top surface of the top layer of cooked loess and the wellhead of the abandoned vertical shaft 1 is 2m~3m.

[0065] In the process of sealing the entire abandoned vertical shaft 1, a layer of drill holes is constructed on the inner wall of the abandoned vertical shaft 1 at h2 below the lower interface of the bottom aquifer 6, a layer of drill holes is constructed on the inner wall of the abandoned vertical shaft 1 at an elevation of h3 on the upper top surface of the bottom aquifer 6, a layer of drill holes is constructed on the inner wall of the abandoned vertical shaft 1 at the top surface of the bottom impermeable layer 7, and a layer of drill holes is constructed on the inner wall of the abandoned vertical shaft 1 above the bottom impermeable layer 7 at vertical intervals of 100m. The number of drill holes in each layer is 8 to 16, and the multiple drill holes in each layer are evenly distributed along the circumference of the abandoned vertical shaft 1. The depth of the drill holes is 4 / 5 of the thickness of the wall of the abandoned vertical shaft 1. The depth of the drill holes needs to ensure that the outer wall of the abandoned vertical shaft 1 is not drilled through, so that the wall thickness meets the stability requirements of water pressure after strength verification. Figure 5 As shown, an expansion agent or explosive 14 is filled in each borehole, and after filling the expansion agent or explosive 14, the borehole is sealed with cement mortar 15, and the detonation fuse of the expansion agent or explosive 14 is led out of the ground through a steel pipe 16 for subsequent cutting and segmenting of the abandoned vertical shaft 1.

[0066] Step 3, cutting and segmenting the abandoned shaft 1 located above the bottom aquifer 6, using a static crushing method or a blasting cutting method to cut and segment the abandoned shaft 1 located above the bottom aquifer 6. By detonating the expansion agent or explosive 14 pre-buried in the borehole of the well wall in step 2, the abandoned shaft 1 (every 100m) is cut and segmented at h2 below the lower interface of the bottom aquifer 6, at the upper elevation h3 of the top surface of the bottom aquifer 6, at the top surface of the bottom aquifer 7, and above the bottom aquifer 7. By adopting the static crushing method or the blasting cutting method, the abandoned vertical shaft 1 is cut at some key strata of the abandoned vertical shaft 1 near the interface between the thick loose layer 5 and the bedrock section 4 of the coal-bearing stratum, near the bottom aquifer 6 and the bottom impermeable layer 7, and above the bottom impermeable layer 7, and the abandoned vertical shaft 1 is segmented in advance. On the one hand, it can avoid the vertical additional force caused by mining subsidence acting on the abandoned vertical shaft 1, which causes the abandoned vertical shaft to slide downward as a whole, and then produce a sliding water-conducting interface; on the other hand, it can prevent the subsequent well wall rupture stratum and the backfill stratum in the wellbore from being inconsistent, which will lead to the reconstruction failure of the bottom aquifer 6 and the bottom impermeable layer 7.

[0067] Step 4, grouting inside the abandoned vertical shaft and reconstruction grouting of the bottom aquifer 6 and the bottom aquifer 7, grouting is performed on the inside of the abandoned vertical shaft 1 through vertical drilling 17 on the construction ground, and grouting is performed on the bottom aquifer 6 and the bottom aquifer 7 outside the abandoned vertical shaft 1 through directional drilling 18 on the construction ground.

[0068] The ground vertical drilling hole 17 is used to perform grouting reinforcement on the area between (h2-2) m below the lower interface of the bottom aquifer 6 inside the abandoned vertical shaft 1 and the upper elevation h3 of the top surface of the bottom aquifer 6. The ground directional drilling hole 18 is used to perform grouting reinforcement on the strata in the area between (h2-2) m below the lower interface of the bottom aquifer 6 outside the abandoned vertical shaft 1 and the upper elevation h3 of the top surface of the bottom aquifer 6. By constructing the ground vertical drilling hole 17 and the ground directional drilling hole 18, grouting is performed on the areas of the bottom aquifer 6 and the bottom aquiclude 7 inside the abandoned vertical shaft 1 and outside the abandoned vertical shaft 1, and the bottom aquifer 6 and the bottom aquiclude 7 conducted by the abandoned vertical shaft 1 are reconstructed into an integral stratum.

[0069] The ground vertical borehole 17 is arranged at the axis of the abandoned vertical shaft 1, and the lower end of the ground vertical borehole 17 is located at (h2-2) m below the lower interface of the bottom aquifer 6. A number of grouting holes 22 are evenly distributed on the side wall of the ground vertical borehole 17 located in the bottom aquifer 6, and the mixed filler of gangue and cement implemented in step 23 is grouting reinforced. Before grouting through the ground vertical borehole 17, it is necessary to first observe the groundwater at the layer to be grouted in the abandoned vertical shaft 1 to determine the hydrostatic pressure of the groundwater. p a , the grouting pressure of the vertical borehole 17 on the ground is the hydrostatic pressure of the groundwater pa 1.5~2.0 times of.

[0070] In one embodiment of the present invention, Figure 6 As shown, the ground directional drilling hole 18 is an S-shaped hole, and the ground directional drilling hole 18 includes an upper straight hole section 19, an inclined hole section 20 and a lower straight hole section 21. The axis of the upper straight hole section 19 and the axis of the lower straight hole section 21 are both parallel to the axis of the abandoned vertical shaft 1. The lower end of the upper straight hole section 19 is located above the bottom impermeable layer, the upper end of the lower straight hole section 21 is located above the bottom aquifer 6, and the lower end of the lower straight hole section 21 is located below the bottom aquifer 6. The two ends of the inclined hole section 20 are respectively connected to the upper straight hole section 19 and the lower straight hole section 21. 9 and the lower straight hole section 21; 8 to 10 ground directional drilling holes 18 are arranged, and the arrangement points of all ground directional drilling holes 18 on the ground are located on a circle with a radius of R3 and the center of the abandoned vertical shaft 1 as the center, R3 = 10m ~ 20m, the hole spacing between the arrangement points of the ground directional drilling holes 18 on the ground is 10m ~ 15m, and the distance between the axis of the lower straight hole section 21 and the outer wall of the abandoned vertical shaft 1 is R3 / 2; a number of grouting holes 22 are evenly distributed on the side wall of the lower straight hole section 21.

[0071] In another embodiment of the present invention, Figure 7 As shown, the ground directional drilling hole 18 includes a vertical section 23, an inclined section 24 and a horizontal section 25. The lower end of the vertical section 23 is located above the bottom impermeable layer 7, and the horizontal section 25 is located in the bottom aquifer 6. The two ends of the inclined section 24 are respectively connected to the vertical section 23 and the horizontal section 25. The axis of the horizontal section 25 is perpendicular to the wall of the abandoned vertical shaft 1. The end point of the ground directional drilling hole 18 is 2m~4m away from the outer wall of the abandoned vertical shaft 1; the ground directional drilling hole 18 includes 4 hole groups, and the 4 hole groups are evenly distributed along the circumference of the abandoned vertical shaft 1. Each hole group includes 4 ground directional drilling holes 18, as shown in FIG. Figure 8As shown, the centers of the four layout points on the ground in a hole group are all located on the extension line of a radius of the abandoned vertical shaft 1. On the same cross section, the corresponding layout points of the four hole groups are located on the same circumference with the center of the abandoned vertical shaft 1, and the distance R4 between the centers of the layout points of the ground directional drilling holes 18 and the center of the abandoned vertical shaft 1 is 30m~40m; the end points of the four ground directional drilling holes 18 in a hole group are all located in the bottom aquifer 6, and the end points of the four ground directional drilling holes 18 in a hole group are arranged in sequence from top to bottom. Relative to the height of the bottom aquifer 6, the end points of the four ground directional drilling holes 18 in a hole group are respectively located at 1 / 8, 3 / 8, 5 / 8 and 7 / 8 of the bottom aquifer 6. The four ground directional drill holes 18 in a hole group are hole a, hole b, hole c and hole d from top to bottom, among which hole a is grouted at 1 / 8 of the grouting layer section, hole b is grouted at 3 / 8 of the grouting layer section, hole c is grouted at 5 / 8 of the grouting layer section, and hole d is grouted at 7 / 8 of the grouting layer section. The center of the end point of the four ground directional drill holes 18 in a hole group and the center of the arrangement point are located on the same vertical section.

[0072] In other embodiments of the present invention, according to the basic conditions of the abandoned vertical shaft 1 and the stratum, the ground directional drilling 18 can also use ground vertical drilling 17 or other types of drilling to reconstruct the bottom aquifer 6 and the bottom impermeable layer 7 by grouting.

[0073] Before grouting through the ground directional drilling 18, it is necessary to first conduct groundwater observation at the layer to be grouted outside the abandoned vertical shaft 1 to determine the hydrostatic pressure of the groundwater at the layer to be grouted. p b The grouting pressure of the ground directional drilling hole 18 is the hydrostatic pressure of the groundwater in the layer to be grouted. p b 2.0~2.5 times of.

[0074] Step 5, closing the manhole cover of the abandoned vertical shaft 1, specifically includes the following steps:

[0075] Step 51, excavating the annular manhole cover pit 26, such as Fig. 9 As shown, an annular manhole cover pit 26 with a width of 2m~3m and a depth of d is excavated outward along the outer edge of the abandoned vertical shaft 1.

[0076] Step 52, laying the manhole cover grate 8, using I-beam beams to set up the manhole cover grate 8 at the wellhead of the abandoned vertical shaft 1, and setting a fence 9 around the wellhead of the abandoned vertical shaft 1, such as Fig.11 As shown, the manhole cover grate 8 is constructed by horizontally and vertically arranging I22b I-beams, and the spacing between the I-beams is 0.5m.

[0077] Step 53, pouring manhole cover concrete, pouring concrete into the annular manhole cover pit 26 and the abandoned vertical shaft 1, the concrete model is C30, and the concrete thickness is (d+1)m~(d+2)m.

[0078] The manhole cover grate 8 extends into the concrete in the annular manhole cover pit 26 by no less than 0.3 m; the outer edge of the manhole cover grate 8 is located in the middle position between the outer wall and the inner wall of the annular manhole cover pit 26.

[0079] In step 5, if Fig.10 As shown, according to actual needs, the well wall of the abandoned vertical shaft 1 at a depth of 1m~2m is cut so that the laid manhole cover grate 8 is located below the ground, and the upper surface of the concrete poured in the annular manhole cover pit 26 is controlled to be flush with the ground surface. After the coal seam under the abandoned vertical shaft is mined, soil is laid above the concrete in the manhole cover pit and vegetation is planted to restore the ecology.

[0080] In the above method, according to the actual situation of the project, grouting can also be carried out before the abandoned vertical shaft 1 is cut into sections, and supplementary grouting can be carried out after the cutting and segmenting of the abandoned vertical shaft 1 is completed. That is, after step 2 is completed, step 4 is first implemented, and the bottom aquifer 6 and the bottom impermeable layer 7 are grouted by using the ground vertical drilling 17 and the ground directional drilling 18, and then step 3 is implemented to cut the abandoned vertical shaft 1 into sections. After the cutting and segmenting of the abandoned vertical shaft 1 is completed, supplementary grouting is carried out by using the ground vertical drilling 17 and the ground directional drilling 18. After the supplementary grouting is completed, step 5 is implemented to close the manhole cover of the abandoned vertical shaft 1.

[0081] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0082] A method for backfilling and plugging abandoned shafts in thick loose layers and reconstructing impermeable layers, starting from the interaction between abandoned shafts and thick loose layers under abandoned shaft coal mining, before abandoned shaft coal mining, this method uses the abandoned shaft shaft backfilling and plugging, grouting inside the abandoned shaft shaft, and grouting reinforcement technology of the bottom aquifer 6 outside the abandoned shaft shaft 1, to reconstruct the bottom aquifer 6 and the bottom impermeable layer 7 conducted by the abandoned shaft shaft 1 into an integral stratum, avoiding the formation of a water-conducting interface between the abandoned shaft shaft 1 and the stratum, and ensuring the safety of abandoned shaft coal mining. This method fills the gap in the current prevention and control technology of the water-conducting channel triggered by abandoned shaft coal mining in thick loose aquifers and water seepage along the abandoned shaft, and provides a technical reference for the subsequent recovery of the protective coal pillar of the shaft that is about to be scrapped.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for backfilling and plugging abandoned vertical shafts with thick loose layers and reconstructing water-blocking layers, characterized in that: The steps include: Step 1: Determine the basic conditions of the abandoned shaft and strata. Determine the basic parameters of the abandoned shaft and strata based on the data of the abandoned shaft and on-site investigation; Step 2: Completely seal the abandoned shaft. The abandoned vertical shaft is completely sealed from bottom to top, and the horse head gate and the bottom section of the shaft, the upper layer of the bedrock section of the coal-bearing stratum, the aquifer at the bottom of the thick loose layer, the aquiclude at the bottom of the thick loose layer, and the middle and upper part of the thick loose layer are sealed in sequence; In step 2, the following steps are included: Step 21, seal the horse head gate and the bottom section, construct a closed wall on each side of the horizontal lane of the horse head gate at the bottom of the abandoned vertical shaft, the closed wall is made of C30 reinforced concrete, the outer edge of the closed wall is connected to the inner wall of the horizontal lane, the thickness of the closed wall is 1m~2m, the bottom of the abandoned vertical shaft and the space between the two closed walls are filled with large pieces of waste, the particle size of the large pieces of waste is 25cm~60cm, the large pieces of waste are filled to the upper elevation h1 of the horse head gate, h1=5m~10m, and concrete is pumped into the gaps of the large pieces of waste; Step 22, plugging the upper layer of the bedrock section of the coal-bearing stratum, covering the top surface of the large piece of waste material and concrete at the upper elevation h1 of the horse head gate with a waterproofing membrane, filling the abandoned vertical shaft above the waterproofing membrane with a mixed filler, the mixed filler is a mixture of material and fly ash, the material is gangue, waste rock or tailings, and the mixed filler of material and fly ash is filled to the elevation h2 below the lower interface of the thick loose layer, h2=5m~10m, and the mass ratio of material to fly ash is 10:1~20:1; Step 23, plugging the bottom aquifer of the thick loose layer, laying a waterproofing roll on the top surface of the mixed filler of material and fly ash at h2 below the lower interface of the thick loose layer, filling the mixed filler of material and cement on the waterproofing roll, and filling the mixed filler of material and cement to the upper elevation h3 of the top surface of the bottom aquifer, h3=5m~10m, and the mass ratio of material to cement is 5:1~10:1; In step 23, before plugging the bottom aquifer of the thick loose layer, firstly, the wellbore wall of the abandoned vertical shaft corresponding to the bottom aquifer is reinforced and supported to form a reinforced support system; Step 24, seal the bottom waterproof layer of the thick loose layer, lay a waterproof roll on the top of the mixed filler of material and cement at the upper elevation h3 of the top surface of the bottom aquifer, fill the waterproof roll with cooked loess and tamp it, and fill the cooked loess to the top surface of the bottom waterproof layer; Step 25, sealing the middle and upper part of the thick loose layer, laying waterproofing coiled material on the cooked loess on the top surface of the bottom waterproof layer, alternately filling the waterproofing coiled material with mixed fillers made of materials and fly ash and cooked loess, laying waterproofing coiled material between the mixed fillers and the cooked loess, the top layer of filler in the abandoned vertical shaft in the middle and upper part of the thick loose layer is cooked loess, the filling thickness H1 of each layer of mixed filler in the thick loose layer is 20m~50m, the filling thickness H2 of each layer of cooked loess is 5m~10m, and the distance between the top surface of the top layer of cooked loess and the wellhead is 2m~3m; Step 3: Abandon the shaft and cut it into sections. Cut and segment abandoned vertical shafts located above the bottom aquifer; In step 3, the abandoned vertical shaft at h2 below the lower interface of the bottom aquifer, at the upper elevation h3 of the top surface of the bottom aquifer, and at the top surface of the bottom aquiclude and above the bottom aquiclude are cut and segmented; Step 4: grouting inside the abandoned shaft and reconstruction grouting of the bottom aquifer and bottom aquiclude. Grouting is performed inside the abandoned shaft through vertical drilling on the construction ground, and grouting is performed on the bottom aquifer and bottom impermeable layer outside the abandoned shaft through directional drilling on the construction ground; In step 4, the ground vertical borehole is arranged at the axis of the abandoned shaft, the lower end of the ground vertical borehole is located at (h2-2) m below the lower interface of the bottom aquifer, and a number of grouting holes are evenly distributed on the side wall of the ground vertical borehole located in the bottom aquifer, and the mixed filler of gangue and cement implemented in step 23 is grouting reinforced; In step 4, the ground directional drilling is used to perform grouting reinforcement on the strata in the area between (h2-2) m below the lower interface of the bottom aquifer outside the abandoned shaft and the upper elevation h3 of the top surface of the bottom aquifer; Step 5, seal the manhole cover of the abandoned vertical shaft.

2. The method for backfilling and plugging abandoned vertical shafts in thick loose layers and reconstructing water-blocking layers according to claim 1 is characterized in that: In step 1, the basic parameters of the abandoned shaft and strata include the inner diameter R1 and outer diameter R2 of the abandoned shaft, the thickness M of the shaft wall, the depth H of the shaft, the construction method of the abandoned shaft, the stratification of the strata, the thickness of the thick loose layer, the thickness of the bottom aquifer and the thickness of the bottom impermeable layer.

3. The method for backfilling and plugging abandoned vertical shafts with thick loose layers and reconstruction of water-blocking layers according to claim 1 is characterized in that: In step 23, the reinforcement support system includes grouting anchor rods, channel steel rings and vertical I-beams, one end of the grouting anchor rods is located on the inner side of the shaft wall of the abandoned shaft, and the other end of the grouting anchor rods is located in the stratum outside the abandoned shaft, and the grouting anchor rods are evenly arranged in N layers along the axial direction of the abandoned shaft, N=4-8, and each layer has 8 grouting anchor rods evenly arranged along the circumference of the abandoned shaft; One end of the grouting anchor rod in the topmost layer is located 2m~3m below the upper edge of the well wall of the bottom aquifer section, the axis of the grouting anchor rod in the topmost layer has an upward inclination angle of 10°~20°, and the other end of the grouting anchor rod in the topmost layer extends to 2m~3m inside the bottom aquiclude; One end of the grouting anchor rod in the lowest layer is located 2m to 3m above the lower edge of the well wall of the bottom aquifer section, the axis of the grouting anchor rod in the lowest layer has a downward inclination angle of 10° to 20°, and the other end of the grouting anchor rod in the lowest layer extends to 2m to 3m inside the coal-bearing bedrock layer; The axes of the grouting anchor rods in all layers except the top and bottom layers are perpendicular to the wall of the abandoned vertical shaft; The grouting anchor rods in the topmost layer are symmetrically arranged with the grouting anchor rods in the bottommost layer, and the grouting anchor rods in the remaining layers are staggered, and the vertical layer spacing between one end of the grouting anchor rods in two adjacent layers is 2-3m; The channel steel well ring is a circular structure, and the channel steel well ring is horizontally arranged on the inner wall of the abandoned vertical shaft. The outer diameter of the channel steel well ring is consistent with the inner diameter of the abandoned vertical shaft. There are multiple channel steel well rings, and each layer of the grouting anchor rods is provided with one channel steel well ring. The channel steel well ring is arranged below one end of the grouting anchor rods, and the channel steel well ring is connected to the grouting anchor rods in the corresponding layer; The vertical I-beam is vertically arranged on the inner wall of the abandoned vertical shaft, the length of the vertical I-beam is consistent with the thickness of the bottom aquifer section, the vertical I-beam is connected to multiple channel steel well rings, 4 or 8 vertical I-beams are arranged, and the multiple vertical I-beams are evenly arranged along the circumference of the abandoned vertical shaft.

4. The method for backfilling and plugging abandoned vertical shafts in thick loose layers and reconstructing water-blocking layers according to claim 1 is characterized in that: In the step 2, during the process of plugging the entire abandoned vertical shaft, a layer of boreholes is constructed on the inner wall of the abandoned vertical shaft at a position h2 below the lower interface of the bottom aquifer, a layer of boreholes is constructed on the inner wall of the abandoned vertical shaft at an elevation h3 above the top surface of the bottom aquifer, a layer of boreholes is constructed on the inner wall of the abandoned vertical shaft at the top surface of the bottom aquifer, and a layer of boreholes is constructed on the inner wall of the abandoned vertical shaft at the top surface of the bottom aquifer. A layer of boreholes is constructed on the inner wall of the abandoned vertical shaft above the bottom aquifer at vertical intervals of 100 m, the number of boreholes in each layer is 8 to 16, the multiple boreholes in each layer are evenly distributed along the circumference of the abandoned vertical shaft, and the depth of the boreholes is 4 / 5 of the thickness of the wall of the abandoned vertical shaft; Filling each of the boreholes with an expansion agent or explosive, and sealing the boreholes with cement mortar after filling the expansion agent or explosive, and leading the detonation fuse of the expansion agent or explosive out of the ground through a steel pipe; In step 3, the abandoned vertical shaft is cut and segmented at h2 below the lower interface of the bottom aquifer, at h3 above the top surface of the bottom aquifer, at the top surface of the bottom aquifer, and above the bottom aquiclude by detonating the expansion agent or explosive pre-buried in the borehole in step 2.

5. The method for backfilling and plugging abandoned vertical shafts in thick loose layers and reconstructing impermeable layers according to claim 1 is characterized in that: In step 4, before grouting through the vertical drilling hole on the ground, it is necessary to first observe the groundwater at the layer to be grouted in the abandoned shaft to determine the hydrostatic pressure of the groundwater. p a The ground vertical drilling grouting pressure is the hydrostatic pressure of groundwater. p a 1.5~2.0 times of.

6. The method for backfilling and plugging abandoned vertical shafts in thick loose layers and reconstructing water-blocking layers according to claim 1 is characterized in that: In step 4, before grouting through the ground directional drilling, it is necessary to first observe the groundwater at the layer to be grouted outside the abandoned shaft to determine the hydrostatic pressure of the groundwater at the layer to be grouted. p b The grouting pressure of the ground directional drilling is the hydrostatic pressure of the groundwater at the grouting layer. p b 2.0~2.5 times of.

7. The method for backfilling and plugging abandoned vertical shafts in thick loose layers and reconstructing water-blocking layers according to claim 1 is characterized in that: In step 4, the ground directional drilling includes an upper straight hole section, an inclined hole section and a lower straight hole section, the axis of the upper straight hole section and the axis of the lower straight hole section are both parallel to the axis of the abandoned vertical shaft, the lower end of the upper straight hole section is located above the bottom impermeable layer, the upper end of the lower straight hole section is located above the bottom aquifer, the lower end of the lower straight hole section is located below the bottom aquifer, and the two ends of the inclined hole section are respectively connected to the upper straight hole section and the lower straight hole section; There are 8 to 10 ground directional drilling holes, and all the ground directional drilling holes are arranged on the ground on a circle with the center of the abandoned shaft as the center and a radius of R3, R3 = 10m to 20m, the hole spacing of the ground directional drilling holes on the ground is 10m to 15m, and the distance between the axis of the lower straight hole section and the outer wall of the abandoned shaft is R3 / 2; A plurality of grouting holes are evenly distributed on the side wall of the lower straight hole section.

8. The method for backfilling and plugging abandoned vertical shafts in thick loose layers and reconstructing water-blocking layers according to claim 1 is characterized in that: In step 4, the ground directional drilling includes a vertical section, an inclined section and a horizontal section, the lower end of the vertical section is located above the bottom impermeable layer, the horizontal section is located in the bottom aquifer, the axis of the horizontal section is perpendicular to the wall of the abandoned vertical shaft, and the end point of the ground directional drilling is 2m to 4m away from the outer wall of the abandoned vertical shaft; The ground directional drilling includes 4 hole groups, which are evenly distributed along the circumference of the abandoned vertical shaft, and each hole group includes 4 ground directional drilling holes. The centers of the 4 arrangement points on the ground in one hole group are all located on the extension line of a radius of the abandoned vertical shaft. On the same cross section, the corresponding arrangement points of the 4 hole groups are located on the same circumference with the center of the abandoned vertical shaft. The distance R4 between the center of the arrangement points of the ground directional drilling holes and the center of the abandoned vertical shaft is 30m~40m; The end points of the four ground directional drilled holes in a hole group are all located in the bottom aquifer, and the end points of the four ground directional drilled holes in a hole group are arranged in sequence from top to bottom. Relative to the height of the bottom aquifer, the end points of the four ground directional drilled holes in a hole group are respectively located at 1 / 8, 3 / 8, 5 / 8 and 7 / 8 of the bottom aquifer, and the center of the end points of the four ground directional drilled holes in a hole group and the center of the arrangement point are located on the same vertical section.

9. The method for backfilling and plugging abandoned vertical shafts in thick loose layers and reconstructing water-blocking layers according to claim 1, characterized in that: In the step 5, the following steps are specifically included: Step 51, excavating an annular manhole cover pit, excavating an annular manhole cover pit with a width of 2m~3m and a depth of d along the outer edge of the abandoned vertical shaft; Step 52, laying manhole cover grates, using I-beams to set up manhole cover grates at the wellhead of the abandoned vertical shaft, wherein the manhole cover grates are set up horizontally and vertically using I22b I-beams, and the spacing between the I-beams is 0.5m; Step 53, pouring manhole cover concrete, pouring concrete into the annular manhole cover pit and the abandoned vertical shaft, the concrete model is C30, and the concrete thickness is (d+1)m~(d+2)m; The manhole cover grate extends into the concrete in the annular manhole cover pit by no less than 0.3m; The outer edge of the manhole cover grate is located in the middle between the outer wall and the inner wall of the annular manhole cover pit; In step 5, according to actual needs, the well wall of the abandoned vertical shaft at a depth of 1m~2m is cut so that the laid manhole cover grate is located below the ground, and the upper surface of the concrete poured in the annular manhole cover pit is controlled to be flush with the ground surface.

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