Composite wall and curtain grouting vertical blocking structure and construction method
By separating the composite wall and the grouting curtain axis in the vertical barrier structure of the composite wall and the grouting curtain, and forming a closed system with the curtain grouting holes and HDPE geomembrane, the problems of difficult construction control and seepage damage in the existing technology are solved, and more efficient leakage prevention and control is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA HYDROELECTRIC ENGINEERING CONSULTING GROUP CHENGDU RESEARCH HYDROELECTRIC INVESTIGATION DESIGN AND INSTITUTE
- Filing Date
- 2026-02-03
- Publication Date
- 2026-04-28
AI Technical Summary
Existing flexible cutoff walls and rigid grouting curtains have limitations in terms of seepage prevention performance, applicable geological conditions, and achievable construction depth. They are also difficult to control during construction, prone to seepage damage, and cannot effectively prevent leachate leakage and groundwater infiltration from landfills.
A vertical barrier structure consisting of a composite wall and a grouting curtain is adopted. The central axes of the composite wall and the grouting curtain are not on the same plane. There are grouting holes on the outside of the composite wall that extend downward into the continuous relative waterproof layer. Grouting is used to form a grouting curtain, which is combined with leakage monitoring wells and HDPE geomembrane to form a closed system.
It improves the controllability and simplicity of construction, avoids construction interference, enhances the reliability of the barrier structure and the accuracy of data monitoring, and reduces project investment.
Smart Images
Figure CN121931879A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of seepage prevention, specifically to a vertical barrier structure and construction method for composite walls and curtain grouting. Background Technology
[0002] In recent years, with the advent of the waste incineration era, my country's landfill ecological restoration has entered a stage of rapid development. Currently, there are more than 27,000 informal landfills and 1,885 sanitary landfills in my country, all of which have the problem of leachate leakage and risk. Among them, there are hundreds of large landfills with a scale of millions of tons that urgently need remediation and restoration. However, large municipal solid waste landfills still face many technical bottlenecks in the process of pollution prevention and remediation.
[0003] Existing flexible cutoff walls and rigid grouting curtains have certain limitations in terms of seepage prevention performance, applicable geological conditions, and achievable construction depth. Although the composite vertical barrier system combining shallow flexible walls and deep cement grouting shows good application potential, its material system matching, structural optimization, and long-term control effect still have certain shortcomings.
[0004] Vertical seepage prevention refers to the design and construction of a certain depth and standard impermeable structure below ground level at the boundary of a landfill area, i.e., a seepage-proof (or permeable) structure. For landfills, vertical seepage prevention must utilize the naturally relatively impermeable layer at the bottom of the landfill as the bottom seepage prevention layer. The bottom of the vertical seepage prevention structure extends to a certain depth into this natural relatively impermeable layer, thereby controlling the natural discharge and inflow of groundwater within the landfill area, thus forming a complete and relatively independent hydrogeological unit. In this way, it is possible to prevent leachate from seeping from the landfill area to the outside, while simultaneously effectively blocking groundwater from seeping into the landfill area.
[0005] Conventional composite wall and curtain grouting with coaxial lines involves grouting the wall first and then the curtain, resulting in a long construction period. Furthermore, poor control of the grouting hole inclination can easily cause penetration of the composite wall, making construction control demanding and challenging. Originally, a sealant was poured at the bottom of the composite wall, followed by curtain grouting on both sides. This sudden change in permeability coefficient and large hydraulic gradient makes it prone to seepage damage. If the HPDE membrane fails later, the original structure will be completely destroyed and irreparable. Summary of the Invention
[0006] The main objective of this invention is to provide a vertical barrier structure and construction method for composite walls and curtain grouting, thereby solving the problems mentioned in the background art.
[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: the vertical barrier structure includes a composite wall extending into the discontinuous relative waterproof layer, and a curtain grouting hole extending downward into the continuous relative waterproof layer on the outside of the composite wall. A grouting curtain is formed below the top plate of the discontinuous relative waterproof layer by grouting into the curtain grouting hole. The central axes of the composite wall and the grouting curtain are not on the same plane.
[0008] Preferably, the bottom of the composite wall extends at least 2m below the discontinuous relative waterproof layer;
[0009] The composite wall is an HDPE-bentonite composite wall. An HDPE geomembrane is laid along the central axis inside the composite wall, and bentonite filler is filled on both sides of the HDPE geomembrane.
[0010] Preferably, the bentonite filler is selected according to the site type. After the composite wall is constructed, it will change the natural underground seepage field. Therefore, the site type is the natural site type. When the area of the composite wall below the natural groundwater level on the downstream side accounts for no less than 65%, it is defined as a high-water-level site; otherwise, it is defined as a low-water-level site. In high-water-level sites, cement-bentonite filler is used; in low-water-level sites, soil-bentonite filler is used.
[0011] Preferably, a sealant is added to the bentonite filler used at the bottom of the composite wall to seal the discontinuous relative waterproof layer range of the composite wall insertion.
[0012] The sealant is made by modifying bentonite filler with polymer materials.
[0013] Preferably, an HDPE geomembrane is pre-installed at the top of the composite wall. After the composite wall is constructed, the pre-installed HDPE geomembrane is bent inwards towards the vertical barrier and welded to the sealing structure to form a unified and closed sealing system.
[0014] Preferably, the curtain grouting hole array has two rows, with a row spacing B2 of 1~1.5m, a spacing D of 1.5~2.5m, and a composite wall width B1 of 0.6~1.2m, selected based on the design permeability coefficient and production test.
[0015] Preferably, the distance between the centerline of the grouting curtain and the centerline of the composite wall is not less than (B1 / 2+B2 / 2+0.25) m.
[0016] Preferably, the grouting curtain hole extends no less than 5m from the ground surface to the continuous relative impermeable layer, and the grouting curtain extends no less than 5m from below the top of the discontinuous relative impermeable layer to the continuous relative impermeable layer. The control standard for the grouting curtain is consistent with the permeability coefficient of the discontinuous relative impermeable layer.
[0017] Preferably, after grouting is injected into the curtain grouting holes to form a grouting curtain, the outer row of curtain grouting holes is enlarged to serve as leakage monitoring wells, and the spacing of the leakage monitoring wells is consistent with the length of a single HDPE geomembrane. A UPVC pipe is inserted into the leakage monitoring well, and short-fiber needle-punched geotextile and φ6~8mm graded gravel are filled outside the pipe.
[0018] A construction method for a vertical barrier structure consisting of a composite wall and a grouting curtain wall, comprising the following steps: S1. Based on the site topography and geological conditions and the results of contaminated site exploration, combined with the specifications and calculation analysis, determine the centerline and width of the composite wall and grouting curtain. The centerline of the grouting curtain should be outside the centerline of the composite wall. S2. Use a combination of hydraulic grab bucket and double wheel milling machine to excavate the composite wall trench. High-standard mud slurry should be used for wall protection during the excavation process. S3. During the trench excavation process in step S2, the preliminary geological survey data is reviewed to clarify the location of the top plate of the discontinuous relative aquitard and the natural groundwater level. S4. Use professional geomembrane laying equipment to lay HDPE geomembrane for composite walls; S5. Based on the verification results of step S3, clarify the site category and carry out the preparation and construction of the sealant and bentonite filler at the bottom of the composite wall; the sealant is applied by underwater grouting and the bentonite filler is applied by layered underwater pouring. S6. Drilling of curtain grouting holes: Under the premise of ensuring the safe distance of construction machinery, curtain grouting holes can be constructed simultaneously with steps S4~S5 in the same unit, or they can be constructed one unit later than the composite wall. S7. Grouting is carried out through the curtain grouting holes. The grouting range extends from the discontinuous relative water-resistant layer to below the continuous relative water-resistant layer. The grout is injected into the cracks or pores of the rock mass to form a continuous water-blocking curtain. S8. After the vertical barrier structure is completed, the grouting holes of the outer curtain are enlarged to become leakage monitoring wells. UPVC pipes are inserted into the leakage monitoring wells, and short fiber needle-punched geotextile and φ6~8mm graded gravel are filled outside the pipes. S9 and HDPE geomembrane are welded to the sealing geomembrane to form a unified, closed vertical barrier structure.
[0019] This invention provides a vertical barrier structure and construction method for composite wall and curtain grouting, with the following beneficial effects: 1. The composite wall and curtain grouting axes are separated, avoiding interference from cross-construction, making construction simpler and more controllable, and allowing for simultaneous construction.
[0020] 2. Existing composite walls involve pouring sealant at the bottom and then grouting the curtain walls on both sides. This sudden change in permeability coefficient and large hydraulic gradient makes them prone to seepage damage. This application fully utilizes the natural rock mass as a relatively impermeable layer for seepage prevention, extending the seepage path and enhancing the reliability of the barrier structure.
[0021] 3. The combination of leakage monitoring wells and curtain grouting voids ensures accurate monitoring location, rapid data feedback, and saves on project investment. Attached Figure Description
[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a vertical barrier cross-sectional view of the present invention; Figure 2 This is the present invention. Figure 1 Enlarged view a; Figure 3 This is a top view of the grouting hole arrangement of the composite wall and curtain wall of the present invention; In the diagram: 1. Composite wall; 101. HDPE geomembrane; 102. Bentonite filler; 2. Grouting curtain; 3. Curtain grouting hole; 4. Discontinuous relative waterproof layer; 5. Continuous relative waterproof layer. Detailed Implementation
[0023] Example 1 like Figures 1-3 As shown, a vertical barrier structure and construction method for composite wall and curtain grouting are disclosed. The vertical barrier structure includes a composite wall 1 extending into a discontinuous relative waterproof layer 4, and curtain grouting holes 3 extending downward into a continuous relative waterproof layer 5 on the outer side of the composite wall 1. Grouting is injected into the curtain grouting holes 3 to form a grouting curtain 2 below the top slab of the discontinuous relative waterproof layer 4. The central axes of the composite wall 1 and the grouting curtain 2 are not on the same plane. The separation of the axes of the composite wall 1 and the grouting curtain 2 avoids interference from cross-construction, making construction simpler, more controllable, and allowing for simultaneous construction.
[0024] Preferably, the bottom of the composite wall 1 extends at least 2m below the discontinuous relative waterproof layer 4; The composite wall 1 is an HDPE-bentonite composite wall. An HDPE geomembrane 101 is laid along the central axis inside the composite wall 1, and bentonite filler 102 is filled on both sides of the HDPE geomembrane 101.
[0025] Preferably, the bentonite filler 102 is selected according to the site type. After the composite wall is constructed, it will change the natural underground seepage field. Therefore, the site type is the natural site type. When the area of composite wall 1 below the natural groundwater level on the downstream side accounts for no less than 65%, it is defined as a high-water-level site; otherwise, it is defined as a low-water-level site. In high water level sites, the bentonite filler 102 uses cement-bentonite filler; in low water level sites, the bentonite filler 102 uses soil-bentonite filler.
[0026] Preferably, a sealant is added to the bentonite filler 102 at the bottom of the composite wall 1 to seal the area of the discontinuous relative waterproof layer 4 inserted into the composite wall 1.
[0027] The sealant is modified by adding polymer materials into the bentonite filler 102.
[0028] Preferably, an HDPE geomembrane 101 is pre-installed at the top of the composite wall 1. After the composite wall 1 is constructed, the pre-installed HDPE geomembrane 101 is bent inward to the vertical barrier and welded to the sealing structure to form a unified and closed sealing system.
[0029] Preferably, the curtain grouting hole 3 array has two rows, with a row spacing B2 of 1~1.5m and a spacing D of 1.5~2.5m. The width B1 of the composite wall 1 is 0.6~1.2m, which is selected based on the design permeability coefficient and production test.
[0030] Preferably, the distance between the central axis of the grouting curtain 2 and the central axis of the composite wall 1 is not less than B1 / 2+B2 / 2+0.25m.
[0031] Preferably, the grouting curtain 3 extends from the ground surface to within the continuous relative impermeable layer 5 for no less than 5m, and the grouting curtain 2 extends from below the top of the discontinuous relative impermeable layer 4 to within the continuous relative impermeable layer 5 for no less than 5m. The control standard for the grouting curtain 2 is consistent with the permeability coefficient of the discontinuous relative impermeable layer 4.
[0032] Preferably, after grouting is injected into the curtain grouting holes 3 to form a grouting curtain 2, the outer row of curtain grouting holes 3 is enlarged to serve as leakage monitoring wells, and the spacing of the leakage monitoring wells is consistent with the length of a single HDPE geomembrane 101. A UPVC pipe is inserted into the leakage monitoring well, and short-fiber needle-punched geotextile and φ6~8mm graded gravel are filled outside the pipe.
[0033] Example 2 like Figures 1-3 As shown in Example 1, a construction method for a vertical barrier structure consisting of a composite wall and a curtain grouting is further illustrated, and the method steps are as follows: S1. Based on the site topography and geological conditions and the results of the contaminated site exploration, combined with the specifications and calculation analysis, the central axis and width of composite wall 1 and grouting curtain 2 are proposed. The central axis of grouting curtain 2 should be outside the central axis of composite wall 1. S2. Use a combination of hydraulic grab bucket and double wheel milling machine to excavate the trench for the composite wall 1. High-standard mud slurry should be used for wall protection during the excavation process. S3. During the trench excavation process in step S2, the preliminary geological survey data is reviewed to clarify the location of the top plate of the discontinuous relative aquitard 4 and the natural groundwater level. S4. Use professional geomembrane laying equipment to lay the HDPE geomembrane 101 for composite wall 1; S5. Based on the results of step S3, clarify the site category and carry out the preparation and construction of the bottom sealant and bentonite filler 102 for composite wall 1; the sealant is applied by underwater grouting and the bentonite filler 102 is applied by layered underwater pouring. S6. Drilling of curtain grouting hole 3: Under the premise of ensuring the safe distance of construction machinery, curtain grouting hole 3 can be constructed simultaneously with steps S4~S5 in the same unit, or it can be constructed one unit later than wall 1. S7. Grouting is performed through the curtain grouting hole 3. The grouting range is from the discontinuous relative water-resistant layer 4 to below the continuous relative water-resistant layer 5. The grout is injected into the cracks or pores of the rock mass to form a continuous water-blocking curtain. S8. After the vertical barrier structure is completed, the outer curtain grouting hole 3 is enlarged to become a leakage monitoring well. A UPVC pipe is inserted into the leakage monitoring well, and short fiber needle-punched geotextile and φ6~8mm graded gravel are filled outside the pipe. S9 and HDPE geomembrane 101 are welded to the sealing geomembrane to form a unified, closed vertical barrier structure.
[0034] Example 3 As an engineering example, based on the geotechnical engineering investigation report of the area surrounding the landfill, the site's topography and lithology are summarized as follows: (1) The landfill site is located on a volcanic plateau, with the terrain generally sloping from southeast to northwest and exhibiting undulating topography. The site is approximately 510.00m long from east to west and 632.00m wide from north to south, covering an area of approximately 213,000 m². 2 The landfill is bordered by a cement road to the east, a waste-to-energy incineration plant to the west, dry land to the south (mainly shrubs and scattered trees), and a highway to the north, north of which is a leachate treatment plant. The landfill slopes downwards from the center to the sides, with elevations ranging from 66.48 to 113.46 meters, a difference of 46.98 meters.
[0035] This site survey was conducted for the vertical seepage prevention curtain project around the landfill. The axis is roughly located 5-10m outside the retaining wall of the landfill, generally higher in the southeast and lower in the northwest, with ground elevations generally ranging from 53.8m to 94.0m. A total of 103 boreholes were drilled, with depths ranging from 35.00m to 112.8m, and a total drilling footage of 6223.58m. The basic structure of the soil and rock layers affected by landfill leachate infiltration has been identified.
[0036] (2) The geological lithological characteristics and engineering properties revealed by the exploration are described below, and the relationship between each layer is detailed in the original report.
[0037] 1) Miscellaneous fill layer ① (Q) ml The soil is distributed throughout the site, loose, with a maximum exposed layer thickness of 13.80m and an average thickness of 2.86m. The layer thickness varies greatly, the layer position is unstable, the soil uniformity is poor, and the engineering performance is poor. It is mainly composed of domestic waste and industrial waste such as iron sheets and metal parts, which should be removed during foundation construction.
[0038] 2) Silty clay layer ② (Q) el ( ): Local pores are missing, the strata are relatively stable, the maximum exposed layer thickness is 13.50m, and the average thickness is 0.6m; it is in a plastic state, with an average void ratio of 1.441, an average liquidity index of 0.39, and an average compression coefficient of 0.49MPa-1, belonging to a medium compressibility soil layer. The average number of hammer blows measured in the standard penetration test is 7.8-7.9, and the mechanical strength is average.
[0039] 3) Basalt ③ layer (Q3): Basalt strongly weathered layer, with missing boreholes in some areas, and large variation in thickness (0.2-7.20m). The composition and strength are uneven, the rock core is very broken, the rock is soft and belongs to medium hard soil. Based on comprehensive analysis, the basic quality grade of this rock mass is determined to be Grade V, and the engineering performance is good.
[0040] 4) Basalt layer ④ (Q3): A moderately weathered basalt layer distributed throughout the site. It is very thick, with a vesicular to microvesicular structure, cryptocrystalline texture, and uneven composition, uniformity, and strength. The core is broken to relatively intact, in blocky to columnar form, with some cores being fragmented. The RQD is 10 to 90, and the standard value of the uniaxial saturated compressive strength is 24.16 MPa. It is classified as soft rock. Based on comprehensive analysis, the basic quality grade of this rock mass is determined to be Grade IV, indicating good engineering performance.
[0041] 5) Basalt ④1 (Q3): Slightly weathered basalt layer, with some gaps, relatively thick, with vesicular to microvesicular structure, cryptocrystalline structure, uneven composition and uniformity, intact, in the form of blocky to columnar, RQD=86~98, belonging to soft rock. Based on comprehensive analysis, the basic quality grade of this rock mass is determined to be Grade III, with good engineering performance.
[0042] 6) Silty clay ④2 layers: rock fissure filling material, the maximum exposed layer thickness is 2.20m, the average thickness is 1.75m, locally distributed, plastic, and with general mechanical strength.
[0043] 7) Tuff Layer ⑤ (Q3): Distributed throughout the site, with a loose and fragmented structure, formed by volcanic ash cementation, RQD=8~35, belonging to soft rock, with a basic rock mass quality grade of V, and good engineering performance.
[0044] 8) Basalt ⑥ (Q2): Moderately weathered basalt, distributed throughout the site, with a large thickness, vesicular to microvesicular structure, cryptocrystalline structure, relatively intact rock core, in the form of block to columnar, with local rock core fragmentation, RQD=10~90, belonging to soft rock, basic rock mass quality grade IV, with good engineering performance.
[0045] 9) Basalt ⑥1 (Q2): Slightly weathered basalt, distributed throughout the site, with a large thickness, vesicular to microvesicular structure, cryptocrystalline structure, uneven composition and uniformity, intact, in the form of block to columnar, with local core fragments, RQD=86~98, belonging to rock. Based on comprehensive analysis, the basic quality grade of this rock mass is determined to be Grade III, with good engineering performance.
[0046] Groundwater in the landfill area is mainly found in strongly weathered basalt layer ③, moderately weathered basalt layer ④, tuff layer ⑤, and moderately weathered basalt layer ⑥. Its permeability is controlled by the degree of vesicle and fissure development and the infill material. Silty clay layer ②, slightly weathered basalt layer ④1, and slightly weathered basalt layer ⑥1 have relatively poor permeability and are relatively impermeable. Based on a comprehensive analysis of the measured borehole water levels and the measured water levels from five groundwater monitoring wells around the landfill, combined with regional and lithological factors, it is determined that the hydraulic connection of groundwater within the site is poor, and the distribution of groundwater is controlled by a network of interconnected fissures within a local area. Whether there is a unified groundwater level requires further investigation and verification.
[0047] Based on the results of on-site pumping and pressure tests, and combined with the geological conditions, the following conclusions were drawn: 1) Layer ①, miscellaneous fill, is a highly permeable layer; 2) Layer ②, silty clay, is a weakly permeable layer; the permeability of Layers ③ (strongly weathered basalt), ④ (moderately weathered basalt), ⑤ (strongly weathered tuff), and ⑥ (moderately weathered basalt) is controlled by the degree of tectonic development and the filling material, exhibiting anisotropy, and overall belongs to the medium to weakly permeable layers; 3) Layer ④1, slightly weathered basalt, has a Lurong value of 2.6~5.16 Lu in the pressure test, indicating poor permeability, classifying it as slightly permeable; Layer ⑥1, slightly weathered basalt, has a Lurong value of 4.6 Lu in the pressure test, also indicating poor permeability, classifying it as slightly permeable. Both of these layers can serve as relatively impermeable layers, but Layer ④1, slightly weathered basalt, is shallower and thinner, and is discontinuous on the south, west, and east sides, with some gaps and open sections.
[0048] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be defined as the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.
Claims
1. A vertical barrier structure combining composite wall and curtain grouting, characterized in that: The vertical barrier structure includes a composite wall (1) extending into the discontinuous relative waterproof layer (4), and a curtain grouting hole (3) extending downward into the continuous relative waterproof layer (5) on the outside of the composite wall (1). A grouting curtain (2) is formed below the top plate of the discontinuous relative waterproof layer (4) by grouting into the curtain grouting hole (3). The central axis of the composite wall (1) and the grouting curtain (2) are not on the same plane.
2. The vertical barrier structure for composite wall and curtain grouting according to claim 1, characterized in that: The bottom of the composite wall (1) extends at least 2m below the discontinuous relative waterproof layer (4); The composite wall (1) is an HDPE-bentonite composite wall. An HDPE geomembrane (101) is laid along the central axis inside the composite wall (1), and bentonite filler (102) is filled on both sides of the HDPE geomembrane (101).
3. The vertical barrier structure for composite wall and curtain grouting according to claim 2, characterized in that: The bentonite filler (102) is selected according to the site type. After the composite wall is constructed, it will change the natural underground seepage field. Therefore, the site type is the natural site type. When the area of composite wall (1) below the natural groundwater level on the downstream side accounts for not less than 65%, it is defined as a high water level site; otherwise, it is defined as a low water level site. In high water level sites, the bentonite filler (102) uses cement-bentonite filler; in low water level sites, the bentonite filler (102) uses soil-bentonite filler.
4. The vertical barrier structure for composite wall and curtain grouting according to claim 2, characterized in that: in A sealant is added to the bentonite filler (102) at the bottom of the composite wall (1) to seal the range of the discontinuous relative waterproof layer (4) inserted into the composite wall (1). The sealant is modified by adding polymer materials into the bentonite filler (102).
5. The vertical barrier structure for composite wall and curtain grouting according to claim 2, characterized in that: HDPE geomembrane (101) is reserved at the top of the composite wall (1). After the composite wall (1) is constructed, the reserved HDPE geomembrane (101) is bent to the inside of the vertical barrier and welded to the sealing structure to form a unified and closed sealing system.
6. The vertical barrier structure for composite wall and curtain grouting according to claim 1, characterized in that: The curtain grouting hole (3) array has two rows, with a row spacing B2 of 1~1.5m and a spacing D of 1.5~2.5m. The width B1 of the composite wall (1) is 0.6~1.2m, which is selected based on the design permeability coefficient and production test.
7. The vertical barrier structure for composite wall and curtain grouting according to claim 6, characterized in that: The distance between the central axis of the grouting curtain (2) and the central axis of the composite wall (1) shall not be less than (B1 / 2+B2 / 2+0.25)m.
8. The vertical barrier structure for composite wall and curtain grouting according to claim 1, characterized in that: The grouting curtain (3) extends from the ground surface to within the continuous relative impermeable layer (5) for no less than 5m. The grouting curtain (2) extends from below the top of the discontinuous relative impermeable layer (4) to within the continuous relative impermeable layer (5) for no less than 5m. The control standard for the grouting curtain (2) is consistent with the permeability coefficient of the discontinuous relative impermeable layer (4).
9. The vertical barrier structure for composite wall and curtain grouting according to claim 1, characterized in that: in After grouting into the curtain grouting hole (3) to form a grouting curtain (2), the curtain grouting holes (3) on the outer side are enlarged to be used as leakage monitoring wells. The spacing of the leakage monitoring wells is consistent with the length of a single HDPE geomembrane (101). A UPVC pipe is inserted into the leakage monitoring well, and short-fiber needle-punched geotextile and φ6~8mm graded gravel are filled outside the pipe.
10. The construction method of the vertical barrier structure of composite wall and curtain grouting according to claim 1, the method steps are as follows: S1. Based on the site topography and geological conditions and the results of the contaminated site exploration, combined with the specifications and calculation analysis, the central axis and width of the composite wall (1) and the grouting curtain (2) are proposed. The central axis of the grouting curtain (2) should be outside the central axis of the composite wall (1). S2. Use hydraulic grab bucket and double wheel milling to excavate the composite wall (1) trench. High standard mud slurry should be used for wall protection during the excavation process. S3. During the trench excavation process in step S2, the preliminary geological survey data is reviewed to clarify the location of the top plate of the discontinuous relative water-resistant layer (4) and the natural groundwater level. S4. Use professional geomembrane laying equipment to lay the HDPE geomembrane (101) of the composite wall (1); S5. Based on the results of step S3, clarify the site category and carry out the preparation and construction of the bottom sealant and bentonite filler (102) of the composite wall (1); the sealant is applied by underwater grouting and the bentonite filler (102) is applied by layered underwater pouring. S6. Drilling of the curtain grouting hole (3) can be carried out simultaneously with steps S4~S5 in the same unit, provided that the safe distance of the construction machinery is ensured. Alternatively, it can be carried out one unit later than the composite wall (1). S7. Grouting is performed through the curtain grouting hole (3). The grouting range is from the discontinuous relative water-resistant layer (4) to below the continuous relative water-resistant layer (5). The grout is injected into the cracks or pores of the rock mass to form a continuous water-resistant curtain. S8. After the vertical barrier structure is completed, the outer curtain grouting hole (3) is enlarged into a leakage monitoring well. A UPVC pipe is inserted into the leakage monitoring well, and short fiber needle-punched geotextile and φ6~8mm graded gravel are filled outside the pipe. S9 and HDPE geomembrane (101) are welded to the sealing geomembrane to form a unified, closed vertical barrier structure.