Coal mining subsidence area flood prevention type railway subgrade reinforcing structure and construction method

Abstract

The present application belongs to the technical field of railway subgrade construction, and particularly relates to a coal mining subsidence area flood prevention type railway subgrade reinforcing structure, which comprises a railway subgrade with an inclined slope, the top of the railway subgrade is provided with a track bed, the track bed is fixed with sleepers, the slope of the railway subgrade is provided with a reinforcing layer, the reinforcing layer comprises a geotextile layer, a wire mesh layer and a grouting anchor rod, the geotextile layer is arranged on the slope surface of the railway subgrade, the wire mesh layer is arranged on the geotextile layer, the grouting anchor rod is arranged in the slope of the railway subgrade and is perpendicular to the slope surface, a grouting pipe pile is vertically arranged in the railway subgrade, and the surface of the railway subgrade is sprayed with a concrete layer. The present application forms a composite supporting reinforcing structure through the wire mesh, the geotextile, the grouting anchor rod, the grouting pipe pile, the concrete layer and the grouting mode, plays a good flood prevention and reinforcement role for the railway subgrade, and solves the problems of instability of the existing railway subgrade after soaking in water for a long time and easy washing away after flooding.

Description

Technical Field

[0001] This invention belongs to the field of railway subgrade construction technology, specifically relating to a flood-resistant railway subgrade reinforcement structure and construction method in coal mining subsidence areas. Background Technology

[0002] Among natural disasters affecting railways, flooding is the most destructive. Railway accidents caused by rain and floods occur frequently, resulting in incalculable economic losses. Floods mainly occur in summer and can happen in different regions. Furthermore, with global warming and the increase in extreme weather events, rainstorms and floods will become more frequent. Railway flooding is a line-wide engineering disaster, characterized by the clear "damage to one point affects the entire line" characteristic. Currently, there are no proposed flood-resistant railway subgrade reinforcement structures and construction methods for coal mining subsidence areas. However, flood-resistant reinforcement of railway subgrades in coal mining subsidence areas can help improve the flood resistance of main railway lines under conditions of heavy rainfall and floods. It can also solve problems such as the instability of existing railway subgrades in coal mining subsidence areas after prolonged immersion in water and their susceptibility to being washed away after flooding. This can improve the safety of railway operations and prevent property damage.

[0003] Prior to this invention, Chinese patent “A Method for Treating Post-Construction Settlement Defects in Railway Subgrade” (patent number: CN201510386505.0) disclosed a method for treating post-construction settlement defects in railway subgrade. This method combines lateral radial grouting technology with vertical plastic paving anti-seepage technology to solve the problem of post-construction settlement in railway subgrade. However, it is more limited to using grouting technology to simply fill and reinforce the settled foundation. It mainly reflects the optimization of grouting technology. The technical solution is simple and the reinforcement effect is not good. In particular, when encountering special disasters, the reinforced railway subgrade is prone to damage. It is also not applicable to flood control reinforcement of railway subgrade in coal mining subsidence areas.

[0004] Chinese patent “A composite anchor pile for slope reinforcement” (patent number: CN201410772933.2) discloses a composite anchor pile for slope reinforcement. It improves the overall strength and stability of the slope by using a composite structure of geotextile, anchor and grouting pipe. The solution has a certain effect on slope reinforcement under normal geological conditions, but the effect is not obvious in the roadbed reinforcement in coal mining subsidence areas, and it cannot play a role in flood prevention, especially under special geological disasters such as rainstorms and floods.

[0005] Therefore, there is an urgent need for a flood-resistant railway subgrade reinforcement structure in coal mining subsidence areas to solve the problems of instability of existing railway subgrades after prolonged immersion in water and easy destruction after flooding. Summary of the Invention

[0006] (a) Technical problems to be solved

[0007] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a flood-proof railway subgrade reinforcement structure and construction method for coal mining subsidence areas.

[0008] (II) Technical Solution

[0009] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0010] In a first aspect, embodiments of the present invention provide a flood-resistant railway subgrade reinforcement structure for coal mining subsidence areas, comprising a railway subgrade with inclined slopes, a ballast bed on top of the railway subgrade with sleepers fixed on the ballast bed, and a reinforcement layer on the slope of the railway subgrade. The reinforcement layer includes a geotextile layer, a wire mesh layer, and multiple grouting anchors. The geotextile layer is placed on the slope surface of the railway subgrade, the wire mesh layer is placed on the geotextile layer, and the multiple grouting anchors pass through the geotextile layer and the wire mesh layer and are installed in the slope of the railway subgrade, with the grouting anchors perpendicular to the slope surface. Multiple grouting pipe piles are vertically installed in the railway subgrade, and the surface of the railway subgrade is coated with a concrete layer. The geotextile layer, wire mesh layer, grouting anchors, and grouting pipe piles constitute a rigid-flexible composite structure to resist groundwater soaking and flood erosion in coal mining subsidence areas. Grouting anchors use steel perforated pipes with a tapered lower end and several small holes for grout to flow out. The spacing between adjacent grouting anchors is 1000-1500mm. Grouting pipe piles use steel pipes with a tapered lower end and several small holes for grout to flow out. The spacing between adjacent grouting pipe piles is 1500-2000mm.

[0011] Secondly, embodiments of the present invention also provide a construction method for a flood-resistant railway subgrade reinforcement structure in coal mining subsidence areas, comprising the following steps:

[0012] (1) Formation of railway subgrade;

[0013] (2) Laying geotextile layer and wire mesh layer;

[0014] (3) Install grouting anchor bolts;

[0015] (4) Install grouting pipe piles;

[0016] (5) Shotcrete and grouting.

[0017] Optionally, in step (1), the railway subgrade section located in the depression of the subsidence area is raised to the design elevation to form a railway subgrade with an inclined slope, the slope ratio of the railway subgrade slope being 1:1.5.

[0018] Specifically, the location of the railway subgrade section in the subsidence area, which is prone to water accumulation, is first monitored in detail, and the design elevation is determined. Then, the railway subgrade slope is filled and repaired. During the repair, the slope surface needs to be leveled to facilitate subsequent construction. After the filling is completed, the slope surface needs to be compacted, starting slowly and then speeding up, and starting with static compaction and then vibratory compaction, to ensure that its density is not less than 85%. Then, the quality of the filling construction is checked, and the line is laid out and measured to ensure that the slope ratio is 1:1.5.

[0019] Optionally, in step (2), a geotextile layer is laid on the slope surface of the railway subgrade, with an overlap length of 300mm between adjacent geotextile layers; a wire mesh layer is laid on the geotextile layer, with an overlap length of 100mm between adjacent wire mesh layers.

[0020] Specifically, when laying geotextile, the upper end of the geotextile is fixed above the slope, and then the geotextile roll is laid down along the slope. Anti-slip nails are installed on the slope, and the overlaps are made by sewing. The sewing thread is made of resin material with a minimum tension of not less than 70N. When laying wire mesh, the overlaps are tied with a single-sided snap method. 22 gauge wire is used for tying, cut according to the pre-made dimensions, and a certain thickness is reserved. It is fixed together with the geotextile at the upper edge of the railway subgrade.

[0021] Optionally, in step (3), the grouting anchor is driven into the slope of the railway subgrade, and the grouting anchor is perpendicular to the slope surface to reinforce the railway subgrade.

[0022] Optionally, in step (4), the first grouting pipe pile is vertically driven into the middle position from the ballast of the railway subgrade to the edge of the slope, and other grouting pipe piles are evenly arranged along the slope at intervals of 1500-2000mm; the grouting pipe piles are welded to the grouting anchor rods by threaded steel bars, and the welding position is 100mm away from the end of the grouting anchor rods and the grouting pipe piles, and the diameter of the threaded steel bars is 14mm.

[0023] Optionally, in step (5), the surface of the railway subgrade is sprayed with concrete of grade C20 and the spray thickness is 100mm. After the concrete has solidified for three days, the grouting anchor rods and grouting pipe piles are grouted in sequence. The grouting steps are as follows: first, ordinary silicate pure cement grout is used for grouting. After 2 hours, high suspension, easy dispersion, leak-proof, high strength paste grouting material is used for grouting. The water-cement ratio of ordinary silicate pure cement grout is 1:1.1. The grouting pressure does not exceed 0.4MPa. When the grouting pressure exceeds the above limit and the grout absorption is less than 2.0L / min and the stabilization time is greater than 5min, or the deformation monitoring reaches the safety alarm value, the hole can be closed.

[0024] The beneficial effects of this invention are that by adopting a composite support structure of "wire mesh (geotextile) + grouting anchor rod + pipe pile + concrete layer + grouting", a composite reinforcement technology for railway subgrade in coal mining subsidence areas is formed that combines rigidity and flexibility and internal and external repair. The reinforcement structure is reliable, the method and steps are simple, and the operation is strong. It helps to improve the flood resistance of railway trunk lines under conditions of heavy rainfall and floods. It can also solve the problems of instability of existing railway subgrades in coal mining subsidence areas after prolonged immersion in water and easy destruction after flooding. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0026] Figure 1 This is a schematic diagram of the overall structure of the flood-resistant railway subgrade reinforcement structure for coal mining subsidence areas provided in Embodiment 1 of the present invention.

[0027] Figure 2 This is a schematic diagram of the geotextile structure of the flood-resistant railway subgrade reinforcement structure in the coal mining subsidence area provided in Embodiment 1 of the present invention.

[0028] Figure 3 A schematic diagram of the wire mesh structure of the flood-resistant railway subgrade reinforcement structure in the coal mining subsidence area provided in Embodiment 1 of the present invention.

[0029] Figure 4 This is a schematic diagram of the grouting anchor rod of the flood-proof railway subgrade reinforcement structure in the coal mining subsidence area provided in Embodiment 1 of the present invention.

[0030] Figure 5 This is a schematic diagram of the grouting pipe pile of the flood-proof railway subgrade reinforcement structure in the coal mining subsidence area provided in Embodiment 1 of the present invention.

[0031] Figure 6 This is a flowchart of a construction method for a flood-resistant railway subgrade reinforcement structure in a coal mining subsidence area, as provided in Embodiment 2 of the present invention. Detailed Implementation

[0032] The present invention will now be clearly described with reference to the accompanying drawings and specific embodiments. This description is merely illustrative and is not intended to limit the scope of the invention. Any modifications, equivalent substitutions, or improvements made by those skilled in the art based on the embodiments of the present invention without inventive effort to obtain all other embodiments should be included within the scope of protection of the present invention.

[0033] Example 1

[0034] like Figure 1-5As shown, this embodiment provides a flood-resistant railway subgrade reinforcement structure for coal mining subsidence areas, including a railway subgrade 1 with an inclined slope 4, a track bed 2 on the top of the railway subgrade 1, sleepers 3 fixed on the track bed 2, a reinforcement layer on the slope 4 of the railway subgrade 1, the reinforcement layer including a geotextile layer 5, a wire mesh layer 6 and multiple grouting anchors 7, the geotextile layer 5 is placed on the slope 4 of the railway subgrade 1, the wire mesh layer 6 is placed on the geotextile layer 5, the multiple grouting anchors 7 all pass through the geotextile layer 5 and the wire mesh layer 6 and are installed in the slope 4 of the railway subgrade 1, and the grouting anchors 7 are perpendicular to the slope 4, multiple grouting pipe piles 8 are vertically installed in the railway subgrade 1, and the surface of the railway subgrade 1 is sprayed with a concrete layer.

[0035] The grouting anchor 7 uses a steel pipe with a diameter of 40mm and a wall thickness of not less than 5mm. The lower end of the steel pipe is tapered, and several small holes with a diameter of 10mm are opened within 1m of the lower end of the steel pipe for the outflow of grouting slurry. The spacing between adjacent grouting anchors 7 is 1000mm.

[0036] The grouting pipe piles use steel pipes with a diameter of 100mm and a wall thickness of not less than 6mm. The lower end of the steel pipe is tapered, and several small holes with a diameter of 10mm are opened within 2m of the lower end of the steel pipe for the outflow of grouting slurry. The spacing between adjacent grouting pipe piles 8 is 1500mm.

[0037] By using railway subgrade elevation technology and a composite support structure of "wire mesh (geotextile) + grouting anchor + pipe pile + concrete layer + grouting", a composite reinforcement technology for railway subgrade in coal mining subsidence areas is formed. This technology is well-suited for railway subgrades in coal mining subsidence areas and can play a good role in flood prevention and reinforcement. It can also solve the problems of instability of existing railway subgrades after prolonged immersion in water and easy destruction after flooding.

[0038] Example 2

[0039] This embodiment provides a construction method for a flood-resistant railway subgrade reinforcement structure in a coal mining subsidence area, which mainly describes the construction process of the flood-resistant railway subgrade reinforcement structure in a coal mining subsidence area shown in Embodiment 1.

[0040] like Figure 6 As shown in this embodiment, the construction method of the flood-resistant railway subgrade reinforcement structure in the coal mining subsidence area includes:

[0041] S1 forms the railway subgrade:

[0042] First, a detailed monitoring of the railway subgrade section located in a subsidence area prone to water accumulation was conducted to determine the design elevation. Coal gangue was then transported by truck to raise the railway subgrade fill material until the design elevation was reached, forming a railway subgrade with sloping sides. Next, the railway subgrade slope was filled and repaired. During the repair, the slope surface needed to be leveled to facilitate subsequent construction. After the filling was completed, the slope surface needed to be compacted, starting slowly and gradually increasing the speed, and first static compaction followed by vibratory compaction, to ensure that its density was not less than 85%. Subsequently, the quality of the filling construction was inspected, and the slope ratio was set out to ensure that it was 1:1.5.

[0043] S2 involves laying a geotextile layer and a wire mesh layer:

[0044] A geotextile layer is laid on the slope surface of the railway subgrade. When laying the geotextile, the upper end of the geotextile is fixed above the slope surface, and then the geotextile roll is laid down along the slope surface. Anti-slip nails are set on the slope surface, and the overlap is made by sewing. The sewing thread is made of resin material with a minimum tension of not less than 70N, and the overlap length is 300mm. Then, a wire mesh layer is laid on the geotextile layer. When laying the wire mesh, the overlap is tied with a one-sided snap method. The tying uses No. 22 iron wire, and the overlap length is 100mm. It is cut according to the pre-made size and a certain thickness is reserved. It is fixed together with the geotextile at the upper edge of the railway subgrade.

[0045] Understandably, laying geotextile and wire mesh layers can prevent coal gangue railway subgrade in coal mining subsidence areas from undergoing shear failure and collapsing rapidly under the scouring of water.

[0046] S3 Installation of Grouting Anchor Bolts:

[0047] The grouting anchors use steel perforated pipes with a diameter of 40mm and a wall thickness of 5mm. The lower end of the steel perforated pipe is tapered using a pipe shrinking machine to facilitate insertion into the roadbed. Small holes with a diameter of 10mm are drilled within 1m of the lower end to facilitate grout injection into the roadbed. The spacing between rows of grouting anchors is 1000mm, arranged at a 90-degree angle perpendicular to the slope. Two methods are used for installing the grouting anchors: one is to directly drive the grouting anchor into the roadbed using a hydraulic blasting head with a connecting sleeve; the other is, when large rocks in the roadbed prevent direct driving of the grouting anchor, an extension rod is installed on the hydraulic blasting head. Holes are first drilled in the roadbed, and after drilling, the borehole is thoroughly washed with clean water to remove rock powder and other debris. Then, compressed air is used to dry the water inside the hole before finally inserting the grouting anchor to reinforce the railway roadbed.

[0048] S4 Installation of Grouting Pipe Piles:

[0049] Grouting pipe piles use steel pipes with a diameter of 100mm and a wall thickness of 6mm. The lower end of the steel pipe is tapered using a pipe shrinking machine to facilitate insertion into the roadbed. Small holes with a diameter of 10mm are drilled within a 2m radius of the lower end to facilitate grout injection into the roadbed. The spacing between rows of grouting pipe piles is 1500mm, arranged vertically. The first row of grouting pipe piles is placed in the middle between the ballast and the edge of the roadbed slope, and then evenly distributed along the roadbed slope at the set spacing. The installation of grouting pipe piles is similar to that of grouting anchors, using a hydraulic blasting head on an excavator to drive the grouting pipe piles into the roadbed. When large rocks in the roadbed prevent direct driving of grouting pipe piles, a drill rod and drill bit are installed on the excavator to first drill holes in the roadbed, and then the grouting pipe piles are inserted to a depth of not less than 1m. After the grouting anchor rods and grouting pipe piles are installed, in order to improve the integrity of the grouting anchor rods and grouting pipe piles and to fix the wire mesh, each row of grouting anchor rods and grouting pipe piles is welded together with 14mm diameter threaded steel bars. The welding position of the threaded steel bars to the grouting anchor rods and grouting pipe piles is 100mm away from the end of the grouting anchor rods and grouting pipe piles.

[0050] Understandably, installing grouting pipe piles helps to further improve the integrity and strength of railway subgrade.

[0051] S5 shotcrete and grouting:

[0052] After the grouting anchors, grouting pipe piles, and steel reinforcement welding are completed, shotcrete is applied to the roadbed surface. The concrete grade is C20, and the shotcrete thickness is 100mm. The mixing ratio must be strictly followed, and the accelerator is added during the shotcrete machine feeding process. The shotcrete sequence is from bottom to top, with an appropriate shotcrete speed. During shotcreting, the nozzle should be kept at a suitable distance of 2m from the surface being sprayed, and the shotcrete angle should be as perpendicular as possible to achieve maximum compaction and minimum rebound. Two hours after the shotcrete has set, water curing should be carried out for at least three days. Before shotcreting, the ends of the grouting anchors and grouting pipe piles should be protected with rags to prevent the shotcrete from damaging the threads. Three days after the shotcrete has set, grouting begins. The grouting anchors are grouted first, followed by the grouting pipe piles. The grouting material consists of first injecting ordinary silicate pure cement grout, followed by a high-suspension, easily dispersible, leak-proof, high-strength paste-like grout to compensate for the low solidification rate of ordinary silicate cement grout. The cement grade used is P.O42.5, and the water-cement ratio of the pure cement grout is 1:1.1. A dedicated mixing tank and grouting pump are used for grouting. Two hours after the pure cement grout is injected, a second injection is performed using the high-suspension, easily dispersible, leak-proof, high-strength paste-like grout. The grouting pressure should not exceed 0.4 MPa. If the grouting pressure exceeds the above limit and the grout absorption is less than 2.0 L / min, the stabilization time is greater than 5 minutes, or the deformation monitoring reaches the safety alarm value, the grouting can be terminated. During grouting, a designated person must observe the subgrade conditions near the grouting hole. Grouting should be stopped immediately if leakage, cracking of the shotcrete layer, or bulging is detected. During the grouting process, parameters such as grouting flow rate, grouting pressure, and grout volume should be recorded.

[0053] The embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A flood-resistant railway subgrade reinforcement structure for coal mining subsidence areas, comprising a railway subgrade with inclined slopes, a ballast bed on top of the railway subgrade, and sleepers fixed on the ballast bed, characterized in that: A reinforcement layer is installed on the slope of the railway subgrade. This reinforcement layer includes a geotextile layer, a wire mesh layer, and multiple grouting anchors. The geotextile layer is placed on the slope surface, the wire mesh layer is placed on top of the geotextile layer, and the multiple grouting anchors penetrate both the geotextile and wire mesh layers and are embedded in the slope of the railway subgrade, perpendicular to the slope surface. Multiple grouting pipe piles are vertically inserted into the railway subgrade, and the surface of the railway subgrade is coated with a layer of concrete. The geotextile layer, wire mesh layer, and grouting anchors, along with... The grouting pipe piles form a rigid-flexible composite structure to resist groundwater soaking and flood erosion in coal mining subsidence areas. The grouting anchor rods are made of steel perforated pipes with a tapered lower end and several small holes at the lower end for the grout to flow out. The spacing between adjacent grouting anchor rods is 1000-1500mm. The grouting pipe piles are made of steel pipes with a tapered lower end and several small holes at the lower end for the grout to flow out. The spacing between adjacent grouting pipe piles is 1500-2000mm.

2. A construction method for a flood-resistant railway subgrade reinforcement structure in a coal mining subsidence area as described in claim 1, characterized in that: Includes the following steps: (1) Forming railway subgrade: raising the railway subgrade section located in the depression of the subsidence area to the design elevation to form a railway subgrade with inclined slopes. The slope ratio of the railway subgrade slope is 1:1.

5. (2) Laying geotextile layer and wire mesh layer: laying geotextile layer on the slope surface of railway subgrade, with an overlap length of 300mm between adjacent geotextile layers; laying wire mesh layer on geotextile layer, with an overlap length of 100mm between adjacent wire mesh. (3) Install grouting anchors and drive them into the slope of the railway subgrade, with the grouting anchors perpendicular to the slope surface; (4) Install grouting pipe piles. The first grouting pipe pile is vertically driven into the middle position from the ballast of the railway subgrade to the edge of the slope, and other grouting pipe piles are evenly laid along the slope at a spacing of 1500-2000mm. The grouting pipe piles are welded to the grouting anchor rods by threaded steel bars, and the welding position is 100mm away from the end of the grouting anchor rod and the end of the grouting pipe pile. The diameter of the threaded steel bars is 14mm. (5) Shotcrete and grouting: Shotcrete is sprayed onto the surface of the railway subgrade. The concrete grade is C20 and the spray thickness is 100mm. After the concrete has solidified for three days, the grouting anchor rods and grouting pipe piles are grouted in sequence. The grouting steps are as follows: First, grout with ordinary silicate pure cement slurry. After 2 hours, grout with high suspension, easy dispersion, leak-proof, high-strength paste grouting material. The water-cement ratio of ordinary silicate pure cement slurry is 1:1.1 and the grouting pressure does not exceed 0.4MPa.

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