Underground engineering fixing and sealing pollution structure for existing industrial area and construction method

Abstract

The invention discloses an underground engineering pollution fixing and sealing structure for an existing industrial area and a construction method, the underground engineering pollution fixing and sealing structure is used for fixing and sealing a remaining pollution area under the existing industrial area, and the underground engineering pollution fixing and sealing structure comprises a reinforcing body located under the remaining pollution area and an enclosure structure arranged on the side face of the remaining pollution area. The protective cushion block and the self-waterproof reinforced concrete structure are arranged right above the remaining polluted area; the enclosure structure is also used as a waterproof curtain; and the permeability coefficient of the reinforcing body is not greater than 10-7 cm / s. Polluted soil and water except for a newly-built project do not need to be excavated, the excavation and backfill project amount is prevented from being greatly increased, the monitoring period can be omitted, development and construction of polluted land parcels can be accelerated, the construction period and the construction cost are saved, and meanwhile the safety of the underground project in the operation period after construction is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of underground pollution disposal in existing industrial areas, and in particular to a pollution sealing structure and a construction method for underground engineering in existing industrial areas. Background Art

[0002] With the adjustment of urban industrial structure and renovation of old cities, many historic factories in the central urban area have gradually relocated. The foundation soil and groundwater of the remaining sites usually have changes in pH and increased content of harmful substances.

[0003] Industrial pollution sites usually include inorganic pollution sites, organic pollution sites and complex pollution sites. The pollutants in inorganic pollution sites are mainly heavy metals, cyanide and fluoride; the pollutants in organic pollution sites are mainly volatile organic compounds, semi-volatile organic compounds, pesticides and petroleum hydrocarbons.

[0004] When historical industrial pollution sites are converted into construction land, it is difficult and risky to implement underground projects in the polluted areas. At present, multiphase extraction combined with in-situ injection chemical oxidation technology is usually used to treat groundwater pollution. The initial judgment period for groundwater remediation to meet the standards after treatment is 12 months, and the period for groundwater remediation effect evaluation is 12 months. The land parcel can only be developed and constructed after passing the 2-year inspection period. After the extraction and treatment of underground free water, pollutants may be attached to the soil particles. The 2-year period is used to monitor the rebound of groundwater and the release of attached pollutants to determine whether the relevant concentrations meet the standards.

[0005] When the pollution depth is deeper than the newly built underground project, the pollution within the scope of the underground project can be excavated and repaired in situ. In order to ensure safety during operation, the pollution below the project is also routinely excavated and treated, which will greatly increase the amount of excavation and backfilling work, causing delays in construction period and high costs.

[0006] Therefore, how to achieve underground water stopping and sealing of pollution, ensure the safety of underground projects during operation after completion, block groundwater from rebounding to the floor of newly built underground projects, avoid secondary pollution exceeding the standard due to the release of pollutants attached to the soil, and thereby omit the conventional 2-year monitoring period has become a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0007] In view of the above-mentioned defects of the prior art, the present invention provides a pollution sealing structure and construction method for underground projects in existing industrial areas, which aims to achieve the purpose of not having to excavate contaminated soil and water other than new projects, but also to save the monitoring period to speed up the development and construction of contaminated plots, while ensuring the safety of underground projects during operation after completion.

[0008] To achieve the above-mentioned purpose, the present invention discloses a pollution sealing structure for underground engineering in an existing industrial zone, which is used to seal a legacy pollution area located underground in an existing industrial zone, and includes a reinforcement body arranged directly below the legacy pollution area, a protective structure arranged on the side of the legacy pollution area, and a protective pad and a self-waterproof reinforced concrete structure arranged directly above the legacy pollution area;

[0009] The enclosure structure also serves as a water-stop curtain;

[0010] The permeability coefficient of the reinforcement is not greater than 10 -7 cm / s.

[0011] Preferably, the protective pad is in the shape of a plate, and is arranged between the residual contaminated area and the self-waterproof reinforced concrete structure, and includes one or more middle pads located at the center, and a plurality of edge pads arranged around the middle pad;

[0012] Each of the edge pads and each of the middle pads comprises, from bottom to top, a self-waterproof concrete layer with a steel mesh arranged inside, a HDPE shell and two pre-laid P-type polymer waterproof membranes;

[0013] The HDPE shell of each edge pad has an end armpit at the edge position;

[0014] The thickness of the two pre-laid P-type polymer waterproofing membranes is not less than 1.2 mm; wherein the pre-laid P-type polymer waterproofing membrane located on the upper side includes a sand layer isolation layer, a main material and an adhesive layer from top to bottom, and the pre-laid P-type polymer waterproofing membrane located on the lower side includes a plastic film isolation layer, a main material and an adhesive layer from top to bottom;

[0015] Every two adjacent middle pads, every two edge pads, or every middle pad and an adjacent edge pad are connected by matching grooves and tenons;

[0016] The groove or tenon of each of the middle pads and each of the edge pads is arranged on the side where the corresponding self-waterproof concrete layer is connected to the corresponding middle pad or the corresponding edge pad.

[0017] The two pre-laid P-type polymer waterproof membranes of each middle pad and each edge pad correspond to the corresponding self-waterproof concrete layer with the groove or the tenon, and one side of the side of the groove or the tenon is more than 250 mm away from the side of the groove or the tenon.

[0018] More preferably, the thickness of each self-waterproof concrete layer is not less than 200 mm; the size of the end corners of each HDPE shell is 30 mm × 30 mm; the diameter of the steel bars of each steel mesh is φ8 mm, and the single row and bidirectional arrangement are 200 mm × 200 mm in intervals, and are fixed with φ10 mm fixed bars arranged at intervals of 1000 mm.

[0019] More preferably, every two adjacent middle pads, every two edge pads, or each middle pad and the adjacent edge pad are connected by two sets of matching grooves and corresponding tenons, and the two sets of matching grooves and corresponding tenons are respectively located on the upper side and the lower side of the corresponding steel mesh;

[0020] The groove depth and tenon height of a group of the grooves and the corresponding tenons located above any of the steel meshes are greater than the groove depth and tenon height of another group of the grooves and the corresponding tenons located below the corresponding steel mesh.

[0021] More preferably, the enclosure structure is a composite wall including an underground continuous wall and an inner lining wall;

[0022] The underground continuous wall serves as the outer wall of the enclosure structure, and the joint surface formed with the inner lining wall of the inner reinforced concrete structure bears a shear force of no more than 0.7 MPa;

[0023] The underground continuous wall and the self-waterproof reinforced concrete structure located above the protective pad are both cast with waterproof concrete with anti-seepage ability to meet the requirements of waterproofing, crack resistance and durability. The inner lining wall of the self-waterproof reinforced concrete structure is fully coated with cement-based penetrating crystalline waterproof coating and anti-cracking and air barrier additives.

[0024] More preferably, the enclosure structure is a composite enclosure structure including a steel-cement-soil mixing wall or bored cast-in-place piles;

[0025] The composite enclosure structure is cast with silicate cement of not less than P42.5 grade, with a cement content of not less than 20%, a water-cement ratio of 1.5 to 2.0, and a permeability coefficient of not more than 10 -7 cm / s, between the inner lining wall of the self-waterproof reinforced concrete structure, above the protective pad, there are plain concrete force transmission belts and two lining walls pre-laid with P-type polymer waterproofing membranes in sequence from outside to inside;

[0026] The gap between the plain concrete force transmission belt and the protective cushion block is filled with a polyurethane resin system, and the upper part is a backfill compaction layer.

[0027] The present invention also provides a construction method for sealing polluted structures in underground engineering in existing industrial areas, comprising the following steps:

[0028] Step 1, constructing the enclosure structure and the reinforcement body located directly below the residual contaminated area;

[0029] Step 2: Combine the construction of internal support and the requirements for controlling the deformation of foundation pit, make full use of the principle of time and space effect, and excavate the foundation pit in layers, blocks, symmetry and time limit;

[0030] Step 3: After excavating the foundation pit to the designed elevation of the pit bottom, the soil at the pit bottom is tested, and the protective cushion blocks are assembled with staggered seams after reaching the standard;

[0031] When assembling the protective pads, pour fiber concrete to form a tenon to clamp the grooves on the connecting surface between every two adjacent middle pads, between every two edge pads, or between each middle pad and the adjacent edge pad, and then pave two layers of the pre-laid P-type polymer waterproof membrane above the assembly joint;

[0032] The two additional layers of the pre-laid P-type polymer waterproofing membranes overlap with the original two layers of the pre-laid P-type polymer waterproofing membranes, and the overlap width is not less than 100mm;

[0033] Step 4: If the enclosure structure is a composite wall including an underground continuous wall and an inner lining wall, a cement-based penetrating crystalline waterproof coating and an anti-cracking and gas barrier additive are fully coated between the enclosure structure and the inner lining wall of the self-waterproof reinforced concrete structure;

[0034] If the enclosure structure is a composite enclosure structure including a steel-cement soil mixing wall or bored cast-in-place piles, after two lining walls are pre-paved with P-type polymer waterproofing membrane on the outer surface of the inner lining wall of the self-waterproof reinforced concrete structure, a plain concrete force transfer belt is applied and the seams are filled with a polyurethane resin system, and then the soil is backfilled and compacted above the plain concrete force transfer belt to form a backfill compaction layer;

[0035] Step 5: construct the remaining underground structure and backfill with clean soil;

[0036] The remaining underground structure is an internal structure, including a middle plate, a middle partition wall and a top plate.

[0037] Preferably, after completing step 1 and before executing step 2, it is necessary to construct a precipitation well, extract groundwater for testing, and perform ex situ remediation, classified discharge, and in situ chemical oxidation treatment when the groundwater does not meet the standards.

[0038] Beneficial effects of the present invention:

[0039] The present invention does not need to excavate contaminated soil and water other than the new construction project, avoids a large increase in excavation and backfilling engineering volume, can save the monitoring period to speed up the development and construction of contaminated plots, save construction time and cost, and ensure the safety of the underground project during operation after completion.

[0040] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 A schematic diagram of the transverse cross-sectional structure is shown when the enclosure structure is a composite wall including an underground continuous wall and an inner lining wall in one embodiment of the present invention.

[0042] Figure 2 Showing the present invention Figure 1 Schematic diagram of the local enlarged structure at point A in the middle.

[0043] Figure 3 A schematic diagram of the transverse cross-sectional structure is shown when the retaining structure in one embodiment of the present invention is a composite retaining structure including a steel-cement-soil mixing wall or bored cast-in-place piles.

[0044] Figure 4 Showing the present invention Figure 3 Schematic diagram of the local enlarged structure at point B in the middle.

[0045] Figure 5 A schematic structural diagram of an intermediate pad in an embodiment of the present invention is shown.

[0046] Figure 6 A schematic structural diagram of an edge pad in an embodiment of the present invention is shown.

[0047] Figure 7 A schematic diagram of the structure after the middle pad and the edge pad are spliced ​​together in one embodiment of the present invention is shown. DETAILED DESCRIPTION

[0048] Example

[0049] like Figures 1 to 4 As shown, the contaminated structure for underground engineering in an existing industrial zone is used to seal the residual contaminated area 1 located underground in the existing industrial zone, including a reinforcement body 2 arranged directly below the residual contaminated area 1, a retaining structure 3 arranged on the side of the residual contaminated area 1, and a protective cushion block 4 and a self-waterproof reinforced concrete structure 5 arranged directly above the residual contaminated area 1;

[0050] The enclosure structure 3 also serves as a water-stop curtain;

[0051] The permeability coefficient of reinforcement 2 is not greater than 10 -7 cm / s.

[0052] like Figures 5 to 7 As shown, in some embodiments, the protective pad 4 is in the shape of a plate, arranged between the residual contaminated area 1 and the self-waterproof reinforced concrete structure 5, including one or more middle pads 41 located at the center, and multiple edge pads 42 arranged around the middle pad; the sizes of the middle pads 41 and the edge pads 42 can be flexibly determined according to the actual project.

[0053] Each edge pad 42 and each middle pad 41 includes, from bottom to top, a self-waterproof concrete layer 401 with a steel mesh 402 arranged inside, a HDPE shell 403 and two pre-laid P-type polymer waterproof membranes 404;

[0054] The HDPE shell 403 of each edge pad 42 has end corners at the edge position; the existence of the end corners can facilitate the shape-flanging processing of the pre-laid P-type polymer waterproof membrane 424.

[0055] The thickness of the two pre-laid P-type polymer waterproofing membranes 404 is not less than 1.2 mm; the pre-laid P-type polymer waterproofing membrane 404 located on the upper side includes a sand layer isolation layer, a main material and an adhesive layer from top to bottom, and the pre-laid P-type polymer waterproofing membrane 404 located on the lower side includes a plastic film isolation layer, a main material and an adhesive layer from top to bottom;

[0056] Every two adjacent middle pads 41, every two edge pads 42, or every middle pad 41 and the adjacent edge pad 42 are connected by matching grooves 405 and tenons 406;

[0057] The groove 405 or the tenon 406 of each middle pad 41 and each edge pad 42 is arranged on the side where the corresponding self-waterproof concrete layer 401 is connected with the corresponding middle pad 41 or the corresponding edge pad 42.

[0058] The two pre-laid P-type polymer waterproof membranes 404 of each middle pad 41 and each edge pad 42 correspond to the corresponding self-waterproof concrete layer 401 with a groove 405 or a tenon 406, and one side of the side is more than 250 mm away from the side of the groove 405 or the tenon 406.

[0059] In some embodiments, the thickness of each self-waterproof concrete layer 401 is not less than 200 mm; the size of the end corners of each HDPE shell 403 is 30 mm × 30 mm; the diameter of the steel bars of each steel mesh 402 is φ8 mm, and the single row and bidirectional arrangement are 200 mm × 200 mm in intervals, and are fixed with φ10 mm fixed bars 407 arranged at intervals of 1000 mm.

[0060] In some embodiments, every two adjacent middle pads 41, every two edge pads 42, or every middle pad 41 and an adjacent edge pad 42 are connected by two sets of matching grooves 405 and corresponding tenons 406, and the two sets of matching grooves 405 and corresponding tenons 406 are respectively located on the upper side and the lower side of the corresponding steel mesh 402;

[0061] The groove depth and tenon height of a set of grooves 405 and corresponding tenons 406 located above any steel mesh 402 are greater than the groove depth and tenon height of another set of grooves 405 and corresponding tenons 406 located below the corresponding steel mesh 402.

[0062] In some embodiments, the enclosure structure 3 is a composite wall including an underground continuous wall and a lining wall;

[0063] The underground continuous wall is the outer wall of the enclosure structure 3, and the joint surface formed by the inner lining wall of the reinforced concrete structure bears a maximum shear force of no more than 0.7MPa;

[0064] The underground continuous wall and the self-waterproof reinforced concrete structure 5 located above the protective pad 4 are both cast with waterproof concrete with anti-seepage ability to meet the requirements of waterproofing, crack resistance and durability. The inner lining wall 51 of the self-waterproof reinforced concrete structure 5 is fully coated with cement-based penetrating crystalline waterproof coating and anti-cracking and air barrier additives.

[0065] In some embodiments, the retaining structure 3 is a composite retaining structure including a steel-cement-soil mixing wall or bored cast-in-place piles; the bonding surface between the composite retaining structure and the inner lining wall 51 of the self-waterproof reinforced concrete structure 5 does not bear shear force.

[0066] The composite enclosure structure is cast with silicate cement of not less than P42.5 grade, with cement content not less than 20%, water-cement ratio of 1.5 to 2.0, and permeability coefficient not more than 10 -7 cm / s, between the inner lining wall 51 of the self-waterproof reinforced concrete structure 5, above the protective pad 4, there are plain concrete force transmission belts 6 and two lining walls pre-laid with P-type polymer waterproof membranes 7 in sequence from outside to inside;

[0067] The gap between the plain concrete force transmission belt 6 and the protective cushion block 4 is filled with polyurethane resin, and the upper part is a backfill compaction layer 62.

[0068] The present invention also provides a construction method for sealing polluted structures in underground engineering in existing industrial areas, comprising the following steps:

[0069] Step 1, constructing a protective structure 3 and a reinforcement body 2 located directly below the remaining contaminated area 1;

[0070] Step 2: Combine the construction of internal support and the requirements for controlling the deformation of foundation pit, make full use of the principle of time and space effect, and excavate the foundation pit in layers, blocks, symmetry and time limit;

[0071] Step 3: After excavating the foundation pit to the designed elevation of the pit bottom, conduct soil testing on the pit bottom, and assemble the protective pads 4 with staggered seams after reaching the standard;

[0072] When assembling the protective pads 4, cast fiber concrete to form tenons 406 to clamp between every two adjacent middle pads 41, between every two edge pads 42, or between each middle pad 41 and the adjacent edge pad 42 on the connecting surface of the groove 405, and then two layers of pre-laid P-type polymer waterproof membrane 404 are laid above the assembly joint;

[0073] The two additional layers of pre-laid P-type polymer waterproofing membrane 404 overlap with the original two layers of pre-laid P-type polymer waterproofing membrane 404, and the overlap width is not less than 100mm;

[0074] Step 4: If the enclosure structure 3 is a composite wall including an underground continuous wall and an inner lining wall, a cement-based penetrating crystalline waterproof coating and an anti-cracking and gas barrier additive are fully coated between the enclosure structure 3 and the inner lining wall 51 of the self-waterproof reinforced concrete structure 5;

[0075] If the enclosure structure 3 is a composite enclosure structure including a steel-cement soil mixing wall or bored cast-in-place piles, two lining walls are applied on the outer surface of the inner lining wall 51 of the self-waterproof reinforced concrete structure 5, and the P-type polymer waterproofing membrane 7 is pre-paved, and then a plain concrete force transfer belt 6 is applied and the seams are filled with a polyurethane resin system, and then the soil is backfilled and compacted above the plain concrete force transfer belt 6 to form a backfill compaction layer 62;

[0076] Step 5: construct the remaining underground structure and backfill with clean soil;

[0077] The remaining underground structure is an internal structure, including a middle plate, a middle partition wall and a top plate.

[0078] In some embodiments, after completing step 1 and before executing step 2, it is necessary to construct a precipitation well, extract groundwater for testing, and perform ex situ remediation, classified discharge, and in situ chemical oxidation treatment when the groundwater does not meet the standards.

[0079] In practical applications, by constructing precipitation wells, extracting groundwater for testing, and conducting ex situ remediation when the groundwater does not meet the standards, classified discharge and in situ chemical oxidation treatment can avoid secondary pollution caused by subsequent operations.

[0080] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A contaminated structure for underground projects in existing industrial areas, used to seal the remaining contaminated area (1) located underground in the existing industrial area; characterized in that: It comprises a reinforcement body (2) arranged directly below the residual contaminated area (1), a protective structure (3) arranged on the side of the residual contaminated area (1), and a protective cushion block (4) and a self-waterproof reinforced concrete structure (5) arranged directly above the residual contaminated area (1); The enclosure structure (3) also serves as a water-stop curtain; The permeability coefficient of the reinforcement body (2) is not greater than 10 -7 cm / s.

2. The underground engineering contamination sealing structure for existing industrial areas according to claim 1 is characterized in that: The protective pad (4) is in the form of a plate, and is disposed between the residual contaminated area (1) and the self-waterproof reinforced concrete structure (5), and comprises one or more middle pads (41) located at a central position, and a plurality of edge pads (42) disposed around the middle pads; Each edge pad (42) and each middle pad (41) comprises, from bottom to top, a self-waterproof concrete layer (401) with a steel mesh (402) arranged inside, a HDPE shell (403) and two layers of pre-laid P-type polymer waterproofing membranes (404); The HDPE shell (403) of each edge pad (42) has an end armpit at the edge position; The thickness of the two pre-laid P-type polymer waterproofing membranes (404) is not less than 1.2 mm; wherein the pre-laid P-type polymer waterproofing membrane (404) located at the top includes, from top to bottom, a sand layer isolation layer, a main material, and an adhesive layer, and the pre-laid P-type polymer waterproofing membrane (404) located at the bottom includes, from top to bottom, a plastic film isolation layer, a main material, and an adhesive layer; Every two adjacent middle pads (41), every two edge pads (42), or every middle pad (41) and an adjacent edge pad (42) are connected via matching grooves (405) and tenons (406); The groove (405) or the tenon (406) of each of the middle pads (41) and each of the edge pads (42) is arranged on the side where the corresponding self-waterproof concrete layer (401) is connected to the corresponding middle pad (41) or the corresponding edge pad (42). The two pre-laid P-type polymer waterproof membranes (404) of each of the middle pads (41) and each of the edge pads (42) correspond to the side surfaces of the corresponding self-waterproof concrete layers (401) provided with the grooves (405) or the tenons (406), and one side of each side surface is at least 250 mm away from the side surfaces of the grooves (405) or the tenons (406).

3. The underground engineering contamination sealing structure for existing industrial areas according to claim 2 is characterized in that: The thickness of each self-waterproof concrete layer (401) is not less than 200 mm; the size of the end corner of each HDPE shell (403) is 30 mm×30 mm; the diameter of the steel bars of each steel mesh (402) is φ8 mm, and the single-row and bidirectional arrangement is 200 mm×200 mm, and they are fixed with φ10 mm fixed bars (407) arranged at intervals of 1000 mm.

4. The underground engineering contamination sealing structure for existing industrial areas according to claim 2 is characterized in that: Every two adjacent middle pads (41), every two edge pads (42), or every middle pad (41) and an adjacent edge pad (42) are connected via two sets of matching grooves (405) and corresponding tenons (406), and the two sets of matching grooves (405) and corresponding tenons (406) are respectively located on the upper side and the lower side of the corresponding steel mesh (402); The groove depth and tenon height of a group of the grooves (405) and the corresponding tenons (406) located above any one of the steel meshes (402) are greater than the groove depth and tenon height of another group of the grooves (405) and the corresponding tenons (406) located below the corresponding steel mesh (402).

5. The underground engineering contamination sealing structure for existing industrial areas according to claim 2 is characterized in that: The enclosure structure (3) is a composite wall including an underground continuous wall and an inner lining wall; The underground continuous wall serves as the outer wall of the enclosure structure (3), and the joint surface formed with the inner lining wall of the inner reinforced concrete structure bears a shear force of no more than 0.7 MPa; The underground continuous wall and the self-waterproof reinforced concrete structure (5) located above the protective pad (4) are both cast with waterproof concrete having anti-seepage capability, meeting the requirements of waterproofness, crack resistance and durability, and the space between the self-waterproof reinforced concrete structure (5) and the inner lining wall (51) is fully coated with cement-based penetrating crystalline waterproof coating and anti-cracking and gas barrier additives.

6. The underground engineering contamination sealing structure for existing industrial areas according to claim 2 is characterized in that: The enclosure structure (3) is a composite enclosure structure including a steel-cement soil mixing wall or bored cast-in-place piles; The composite enclosure structure is cast with silicate cement of not less than P42.5 grade, with a cement content of not less than 20%, a water-cement ratio of 1.5 to 2.0, and a permeability coefficient of not more than 10 -7 cm / s, between the inner lining wall (51) of the self-waterproof reinforced concrete structure (5), above the protective pad (4), there are a plain concrete force transmission belt (6) and two lining walls pre-laid with P-type polymer waterproofing membranes (7) in sequence from the outside to the inside; The gap between the plain concrete force transmission belt (6) and the protective cushion block (4) is filled with a polyurethane resin system, and a backfill compaction layer (62) is formed above.

7. The construction method for sealing polluted structures in underground engineering in existing industrial areas according to claim 1 is characterized in that: The steps include: Step 1, constructing the enclosure structure (3) and the reinforcement body (2) located directly below the residual contaminated area (1); Step 2: Combine the construction of internal support and the requirements for controlling the deformation of foundation pit, make full use of the principle of time and space effect, and excavate the foundation pit in layers, blocks, symmetry and time limit; Step 3, after excavating the foundation pit to the designed elevation of the pit bottom, the soil at the pit bottom is tested, and after reaching the standard, the protective cushion blocks (4) are assembled with staggered seams; When assembling the protective pads (4), fiber concrete is poured to form a tenon (406) to engage between every two adjacent middle pads (41), between every two edge pads (42), or between each middle pad (41) and the adjacent edge pad (42) The groove (405) on the connecting surface, and then two layers of the pre-laid P-type polymer waterproof membrane (404) are laid above the assembly joint; The two additional layers of the pre-laid P-type polymer waterproofing membrane (404) overlap with the original two layers of the pre-laid P-type polymer waterproofing membrane (404), and the overlap width is not less than 100 mm; Step 4: If the enclosure structure (3) is a composite wall including an underground continuous wall and an inner lining wall, a cement-based penetrating crystalline waterproof coating and an anti-cracking and gas barrier additive are fully coated between the enclosure structure (3) and the inner lining wall (51) of the self-waterproof reinforced concrete structure (5); If the enclosure structure (3) is a composite enclosure structure including a steel-cement soil mixing wall or bored cast-in-place piles, two lining walls are applied on the outer surface of the inner lining wall (51) of the self-waterproof reinforced concrete structure (5) and pre-laid with a P-type polymer waterproofing membrane (7), then a plain concrete force transfer belt (6) is applied and the seams are filled with a polyurethane resin system, and then backfill soil is compacted above the plain concrete force transfer belt (6) to form a backfill compaction layer (62); Step 5: construct the remaining underground structure and backfill with clean soil; The remaining underground structure is an internal structure, including a middle plate, a middle partition wall and a top plate.

8. The construction method for sealing polluted structures in underground engineering in existing industrial areas according to claim 2 is characterized in that: After completing step 1 and before executing step 2, it is necessary to construct a precipitation well, extract groundwater for testing, and perform ex situ remediation, classified discharge, and in situ chemical oxidation treatment when the groundwater does not meet the standards.

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