Existing underground diaphragm wall heightening and recycling construction method

Abstract

The invention relates to an existing underground diaphragm wall heightening recycling construction method which comprises the following steps that foundation trench excavation is conducted on the two sides of an existing underground diaphragm wall, and the foundation trench excavation is conducted to the distance set below a top beam of the existing underground diaphragm wall so that the top of the existing underground diaphragm wall can be exposed; the existing diaphragm wall is detected, and the existing diaphragm wall is reinforced according to a detection result; chiseling a top beam at the top of the existing diaphragm wall and a part with a set distance below the top beam, drilling a plurality of pipe holes along the central line of the top surface of the chiseled existing diaphragm wall, and placing steel pipes in the pipe holes; planting steel bars on the two sides of the top surface of the chiseled existing diaphragm wall; pouring a heightened underground diaphragm wall on the top surface of the existing underground diaphragm wall to form a new underground diaphragm wall; performing waterproof treatment on the junction part of the existing diaphragm wall and the heightened diaphragm wall; by adopting the method disclosed by the invention, the reutilization of the existing diaphragm wall is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of underground engineering construction, and particularly relates to a construction method for connecting and reusing an existing diaphragm wall. Background Art

[0002] The statements herein only provide the background art related to the present invention and do not necessarily constitute the prior art.

[0003] The development and utilization of underground space have become an important way to relieve urban traffic pressure, improve the bearing capacity of infrastructure, and improve the urban ecological environment. As a key supporting structure in underground engineering, the diaphragm wall can not only effectively prevent the collapse of the formation and the structural damage caused by the rise of the groundwater level, but also significantly reduce the deformation during the foundation pit excavation through its rigidity and continuity.

[0004] However, as a temporary support structure, the diaphragm wall is abandoned in the formation due to its functional failure after the completion of the main structure. In the current reconstruction and expansion projects of underground structures, the demand for developing foundation pits close to existing structures frequently appears. The existing abandoned diaphragm walls often interfere with the new projects and affect the construction space. Therefore, carrying out the reuse of existing diaphragm walls is of great practical significance for promoting the efficient and sustainable development of underground space. However, there are usually significant differences between the new underground structure and the existing structure in many aspects. The height of the existing diaphragm wall is often difficult to meet the requirements of the new project and cannot be directly put into use. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a construction method for connecting and reusing an existing diaphragm wall, which realizes the reuse of the existing diaphragm wall in the new project. By avoiding the demolition of the existing structure, the construction procedures of building a temporary support system and reconstructing the foundation structure are reduced, and the repeated investment of resources is significantly reduced.

[0006] To achieve the above purpose, the present invention is realized through the following technical solutions:

[0007] An embodiment of the present invention provides a construction method for connecting and reusing an existing diaphragm wall, including the following steps:

[0008] Excavate the foundation trenches on both sides of the existing diaphragm wall. The foundation trenches are excavated to a distance below the capping beam of the existing diaphragm wall to expose the top of the existing diaphragm wall.

[0009] Detect the existing diaphragm wall and reinforce the existing diaphragm wall according to the detection results.

[0010] Chisel off a part of the top capping beam of the existing diaphragm wall and a part at a set distance below the capping beam, drill a plurality of pipe holes along the center line of the top surface of the existing diaphragm wall after chiseling and place steel pipes in the pipe holes; implant steel bars on both sides of the top surface of the existing diaphragm wall after chiseling;

[0011] Pour a heightened diaphragm wall on the top surface of the existing diaphragm wall to form a new diaphragm wall;

[0012] Conduct waterproof treatment on the joint part of the existing diaphragm wall and the heightened diaphragm wall;

[0013] Backfill the foundation trench.

[0014] Optionally, slope excavation is carried out on both sides of the existing diaphragm wall according to a set slope to form a foundation trench.

[0015] Optionally, when excavating the foundation trench, an excavation method of staggering multiple working faces in layers is adopted for excavation.

[0016] Optionally, the detection method for the existing diaphragm wall is as follows:

[0017] Drill holes at regular intervals along the extension direction of the existing diaphragm wall on both sides of the existing diaphragm wall, then lower a transmitting transducer and a receiving transducer into the drill holes on both sides of the existing diaphragm wall respectively. The transmitting transducer and the receiving transducer are kept at the same depth, and the existing diaphragm wall is detected for abnormal parts by using the transmitting transducer and the receiving transducer.

[0018] Optionally, the reinforcement method for the existing diaphragm wall is as follows:

[0019] After detecting the abnormal part of the existing diaphragm wall, drill holes from the position of the top surface of the existing diaphragm wall corresponding to the abnormal part, and obtain the specific position and damage degree of the defect in the abnormal part of the existing diaphragm wall through hole-in-camera technology;

[0020] Inject grout for reinforcement at the defect position of the existing diaphragm wall through the existing core drilling holes on the top surface of the existing diaphragm wall and / or the new drilling holes on the top surface of the existing diaphragm wall.

[0021] Optionally, after the steel pipe is inserted into the pipe hole, the gap between the steel pipe and the hole surface of the pipe hole is filled with grout injection of micro-expansion grouting material.

[0022] Optionally, the specific method for implanting steel bars is as follows:

[0023] Drill holes on both sides of the top surface of the existing diaphragm wall after chiseling, then inject structural adhesive into the drill holes, and then rotate and insert the steel bars into the drill holes.

[0024] Optionally, the pouring method for the heightened diaphragm wall is as follows:

[0025] Lift the steel reinforcement cage of the connecting high ground diaphragm wall to the top surface of the existing diaphragm wall after chiseling, and lap the steel reinforcement of the steel reinforcement cage with that of the existing diaphragm wall after chiseling.

[0026] Support formwork above the top surface of the existing diaphragm wall after chiseling, then pour concrete for the connecting high ground diaphragm wall, and cure the concrete of the connecting high ground diaphragm wall after pouring.

[0027] Optionally, the specific method of waterproof treatment is as follows:

[0028] Grind the surface of the joint part between the existing diaphragm wall and the connecting high ground diaphragm wall and apply a primer, and cover the joint part with a waterproof coiled material.

[0029] Apply a waterproof coating on the outer surface of the waterproof coiled material.

[0030] Cover a steel plate protective layer on the outer periphery of the waterproof coating, and fix the steel plate protective layer with expansion bolts.

[0031] Optionally, the waterproof coating adopts a cement-based penetrating crystalline waterproof coating. After the waterproof coating is applied, cover it with a wet cloth and cure for a set time, and then install the steel plate protective layer after curing.

[0032] The beneficial effects of the present invention are as follows:

[0033] 1. The construction method of the present invention exposes the top end of the existing diaphragm wall through the excavation of the foundation trench. Through the chiseling of the top of the existing diaphragm wall, the construction of steel pipes and the planting of steel bars on the top surface of the existing diaphragm wall after chiseling, and then the pouring of the connecting high ground diaphragm wall, the heightening of the existing diaphragm wall is realized, meeting the requirements of the new project. During the construction of the new project, there is no need to demolish the existing diaphragm wall, reducing the construction procedures of the temporary support system and the reconstruction of the foundation structure, greatly reducing the repeated investment of resources, and realizing the systematic optimization of the recycling rate of building materials, which conforms to the concept of green construction and sustainable development.

[0034] 2. The construction method of the present invention breaks through the height limit of the diaphragm wall through the heightening of the existing diaphragm wall, making it applicable to complex scenarios such as ultra-deep foundation pits and underground space development, with a wider scope of application and improved environmental adaptability.

[0035] 3. The construction method of the present invention detects and reinforces the existing diaphragm wall, improving the wall strength, anti-seepage ability and stability, extending the service life, and ensuring the construction safety of the new project. Description of the Drawings

[0036] The attached drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0037] Figure 1It is the flowchart of the method in Embodiment 1 of the present invention;

[0038] Figure 2 It is the schematic diagram of the foundation trench excavation in Embodiment 1 of the present invention;

[0039] Figure 3 It is the schematic diagram of the detection of the existing diaphragm wall in Embodiment 1 of the present invention;

[0040] Figure 4 It is the schematic diagram of steel pipes and implanted bars in Embodiment 1 of the present invention;

[0041] Figure 5 It is the top view of steel pipes and implanted bars in Embodiment 1 of the present invention;

[0042] Figure 6 It is the schematic diagram of the construction of raising the diaphragm wall in Embodiment 1 of the present invention;

[0043] Figure 7 It is the schematic diagram of the foundation trench backfilling in Embodiment 1 of the present invention;

[0044] Wherein, 1. Existing diaphragm wall, 2. Capping beam, 3. Transmitting transducer, 4. Receiving transducer, 5. Vertical hole, 6. Pipe hole, 7. Steel pipe, 8. Micro-expansion grouting material, 9. Implanted bar, 10. Steel plate protection layer, 11. Reinforcement bars of the existing diaphragm wall, 12. Steel reinforcement cage, 13. Raised diaphragm wall, 14. Waterproof coiled material. Specific implementation manners

[0045] Embodiment 1

[0046] This embodiment provides a construction method for raising and reusing an existing underground continuous wall, as Figure 1 shown, including the following steps:

[0047] Step 1: Construction preparation

[0048] In the stage of project preparation and pre-construction preparation, comprehensively investigate the mutual influence of adjacent project construction, organize a professional team to conduct a detailed review of the construction drawing design documents, and have the design unit carry out a design disclosure. Combining the project characteristics and the actual situation on site, prepare a construction organization design and a special construction plan, and obtain the data of the survey baseline and level points for engineering survey to provide a basis for engineering survey. Do a good job in ensuring water, electricity, and road access in the construction site, and reasonably layout the steel reinforcement cage production platform, mud circulation system, etc. in the site. After the large-scale equipment and hoisting machinery enter the site, install and debug them in a timely manner, and organize a strict inspection and acceptance to ensure that they are in good condition. When the raw materials enter the site, strictly check the product quality certification documents, accept them according to the specifications, and put them into use after passing the inspection.

[0049] Before construction, conduct survey layout and re-survey on the site location and record it in written materials. At the same time, according to the site topography and construction requirements, construct a survey control network consisting of plane control points and level control points on the site. Develop a periodic re-survey plan and do a good job in protecting the control points. For the external dimension of the diaphragm wall, it is necessary to combine the geological exploration report, comprehensively consider the complexity of the geological conditions and the depth of the diaphragm wall, and determine it after scientific calculation and analysis.

[0050] The above steps can adopt existing technologies and will not be described in detail here.

[0051] Step 2: Excavate the foundation trench

[0052] As Figure 2 shown, after completing the operation of lowering the groundwater level, excavate the soil above and on both sides of the existing diaphragm wall to form a foundation trench, so as to expose the top of the existing diaphragm wall 1 and the capping beam 2 at the top. In this embodiment, for the soil on both sides of the existing diaphragm wall, slope excavation is carried out in the form of slope excavation according to the set slope. Preferably, the set slope is 1:1, so the cross-section of the formed foundation trench is V-shaped.

[0053] Furthermore, in order to avoid excessive disturbance to the soil during excavation and improve the construction efficiency, the foundation trench is excavated by using the excavation method of multi-workface layered staggering, and layered unloading is carried out according to the 1:1 slope.

[0054] Excavate the foundation trench until it reaches the working surface at a set distance below the bottom elevation of the capping beam of the existing diaphragm wall. In this embodiment, the set distance is 100 mm. It can be understood that those skilled in the art can select the excavation depth of the foundation trench according to actual needs.

[0055] During the excavation of the foundation trench, mainly use machinery and supplemented by manual work. It can be set according to the actual working conditions and will not be described in detail here.

[0056] Step 3: Detect the existing diaphragm wall 1

[0057] In this embodiment, the symmetric ultrasonic detection method combined with the core drilling method is used to detect whether there are defects in the existing diaphragm wall 1. Specifically, the abnormal parts of the existing diaphragm wall 1 are determined by the symmetric ultrasonic detection method, and the specific positions of the defects in the abnormal part area are detected by the core drilling method.

[0058] As Figure 3As shown in the figure, the symmetric ultrasonic detection method uses a transmitting transducer 3 and a receiving transducer 4. The transmitting transducer 3 and the receiving transducer 4 can be existing equipment, and no detailed description will be given here. First, vertical drilling is carried out on the soil on both sides of the existing diaphragm wall 1 to form vertical holes 5. In this embodiment, along the extension direction of the existing diaphragm wall 1, vertical drilling is carried out at each set distance on both sides of the existing diaphragm wall 1. Preferably, the set distance is 8 meters. It can be understood that those skilled in the art can set the distance between adjacent vertical holes according to actual needs. Then, the transmitting transducer is lowered into one of the vertical holes, and the receiving transducer is lowered into the vertical hole on the other side. During the lowering process, the depths of the transmitting transducer 3 and the corresponding receiving transducer 4 are kept consistent, and the existing diaphragm wall is detected by the flat detection method.

[0059] The existing diaphragm wall 1 is scanned by the transmitting transducer 3, and the refracted ultrasonic signals are collected by the receiving transducer 4. An ultrasonic image is drawn based on the ultrasonic signals to judge the abnormal parts of the existing diaphragm wall 1.

[0060] After detecting the abnormal parts of the existing diaphragm wall 1, drilling is carried out at the position of the top surface of the existing wall corresponding to the abnormal parts, and the drilling depth reaches the abnormal parts. The drilled materials are lifted to the ground, and then the concrete situation in the inspected drill hole is observed comprehensively through the drill hole by using the borehole camera technology, and the specific positions and damage degrees of defects such as internal cavities, fissures, segregation, and cracks in the concrete are accurately obtained, and the existing diaphragm wall is detected in detail, providing a basis for the quality assessment of the diaphragm wall and the formulation of subsequent repair plans.

[0061] The borehole camera technology can adopt existing technology, and no detailed description will be given here.

[0062] Step 4: Strengthen the existing diaphragm wall

[0063] After determining the specific positions of the defects by using Step 3, the defect positions of the existing diaphragm wall are grouted and strengthened through the existing core drilling holes on the top surface of the existing diaphragm wall 1 and / or the new drilling holes on the top surface of the existing diaphragm wall.

[0064] Specifically, if there are core drilling holes on the top surface of the existing diaphragm wall, the existing core drilling holes are preferentially used to carry out the grouting and strengthening operation at the defect positions. If not, drilling needs to be carried out on the top surface of the existing diaphragm wall until the drilling reaches the defect parts.

[0065] If grouting and strengthening are carried out by using new drilling holes, the hole forming quality should be checked immediately after drilling is completed, and the hole is cleared by using high-pressure water or high-pressure air to thoroughly remove impurities such as floating slag and debris in the hole.

[0066] The specific method of grouting and strengthening is as follows:

[0067] Accurately place the injection pipeline into the newly drilled hole and / or the core drilling hole, and connect the injection pipeline with the high-pressure grouting equipment. The high-pressure grouting equipment can use existing equipment, and will not be described in detail here. With the help of the high-pressure grouting equipment, inject epoxy resin glue or sealing glue into the crack area. It is necessary to strictly control the grouting pressure and the grouting volume to ensure that the glue can fully fill the crack and form a firm bonding layer with high bonding strength, thereby effectively improving the integrity and stability of the wall.

[0068] After the grouting operation is completed, use cement mortar or expansive cement slurry for hole sealing treatment. After the hole sealing is completed, it is necessary to reasonably maintain the hole sealing part according to the relevant specification requirements to ensure that the hole sealing quality meets the engineering requirements.

[0069] In this embodiment, the existing diaphragm wall defects are accurately positioned by ultrasonic detection technology, and combined with targeted repair and reinforcement processes to improve the wall strength, anti-seepage ability and stability, extend the service life, and achieve safe and efficient reinforcement.

[0070] Step 5: Construction of the heightening of the existing diaphragm wall. Construct a heightening diaphragm wall on the top surface of the existing diaphragm wall to form a new diaphragm wall, including the following specific steps:

[0071] Step 5.1: Chisel off the capping beam 2 part of the existing diaphragm wall 1 and the part at a set distance below the capping beam. In this embodiment, the existing diaphragm wall 1 is chiseled to a position 100 mm below the capping beam. It can be understood that those skilled in the art can determine the chiseled part of the existing diaphragm wall according to actual needs.

[0072] Step 5.2: Perform chiseling treatment on the top surface and side surface of the existing diaphragm wall 1 after chiseling, remove the loose concrete, remove the residual aggregate on the base surface, and expose the main structure of the existing diaphragm wall.

[0073] Step 5.3: As Figures 4 - 5 shown, drill a plurality of pipe holes 6 along the top surface center line on the top surface of the existing diaphragm wall 1 after chiseling. The pipe holes 6 are round holes. In this embodiment, the depth of the round hole is 0.5 m, and the adjacent round holes are spaced 0.5 m apart. Insert a steel pipe 7 with a length of 1 m into the round hole, and then use micro-expansion grouting material 8 to grout and fill the gap between the steel pipe and the round hole.

[0074] In this embodiment, the length of the steel pipe 7 above the existing diaphragm wall is equal to the length of the part extending into the round hole. The steel pipe is used to anchor the existing diaphragm wall 1 and the heightening diaphragm wall 13, and the anchoring length is half of the length of the steel pipe 7.

[0075] Step 5.4: Rebar planting 9 is carried out along the two side edges on the top surface of the existing diaphragm wall 1 after chiseling. Preferably, HRB400 steel bars with a diameter of 32 mm are selected for rebar planting, and the length of the rebar planting 9 is 750 mm. Through the rebar planting 9, the connection stability between the existing diaphragm wall 1 and the extended diaphragm wall 13 is strengthened.

[0076] The specific method of rebar planting is as follows: Drill holes along the two side edges on the top surface of the existing diaphragm wall after chiseling, and then clean the holes. Use a glue injector to inject structural adhesive into the drilled holes. Preferably, the structural adhesive uses modified epoxy-based structural adhesive or modified vinyl ester-based structural adhesive. Existing structural adhesives can be used, and no detailed description will be given here. After the injection of the structural adhesive is completed, slowly rotate the steel bar and then insert it into the drilled hole to ensure that the steel bar reaches the bottom of the hole. The rebar planting spacing, steel bar diameter, and the entire rebar planting construction process shall all comply with the requirements of the Specification for Post-anchoring Technology in Concrete Structures JGJ 145. The distance between the rebar planting 9 and the side surface of the existing diaphragm wall 1 is not less than 50 mm, and the spacing between adjacent rebar plantings 9 is not less than 5 times the diameter of the rebar planting 9.

[0077] Step 5.5: As Figure 6 shown, according to the elevation requirements of the new structure, design the reinforcement cage for the extended section of the existing diaphragm wall 1, position and calibrate the precast reinforcement cage 12 to ensure that the upper reserved parts of the steel pipe 7 and the rebar planting 9 can be embedded in the precast reinforcement cage. Use a large crawler crane to hoist the reinforcement cage 12 of the extended diaphragm wall into place, so that the reinforcement cage is hoisted to the top surface of the existing diaphragm wall. Use the existing mechanical connection process to achieve reliable lapping between the steel bars 11 of the existing diaphragm wall and the reinforcement cage 12 of the extended diaphragm wall, ensure the continuity of structural force transmission, and connection strength detection shall be carried out throughout the construction process.

[0078] Step 5.6: Support the formwork above the top surface of the existing diaphragm wall. In this embodiment, there are tie bolts between the two side formworks, and a back lining reinforcement system is set outside the formwork to ensure the stiffness and stability of the formwork system. The setting methods of the tie bolts and the back lining reinforcement system can adopt existing technologies, and no detailed description will be given here. After the formwork support is completed, start the concrete pouring of the extended diaphragm wall 13. The concrete pouring adopts layered continuous operation. Avoid the area near the steel pipe during vibration. After the pouring is completed, implement the standardized curing process, adopt film covering and moisturizing and temperature control measures to ensure that the development of concrete strength meets the design requirements.

[0079] Step 6: As Figure 7 shown, waterproof treatment is carried out on the junction part of the existing diaphragm wall and the extended diaphragm wall. The waterproof measures shall meet the relevant technical requirements in the Technical Code for Waterproofing of Underground Engineering GB 50108 - 2008, and specifically include the following steps:

[0080] Step 6.1: After the curing of the concrete of the connecting high retaining wall is completed, grind the joint part between the connecting high retaining wall and the existing retaining wall, remove the floating slurry and apply a primer.

[0081] Step 6.2: Wrap a waterproof coiled material 14 around the outer periphery of the joint part between the existing retaining wall and the connecting high retaining wall.

[0082] In this embodiment, the waterproof coiled material is a 1.5-mm-thick polymer self-adhesive film waterproof coiled material. Cut the waterproof coiled material into strip shapes, and then wind and cover it on the joint part between the existing retaining wall and the connecting high retaining wall. The waterproof coiled material covers the existing retaining wall and the connecting high retaining wall by 300 mm along the axial direction. Lay it from bottom to top, expel the air, ensure full adhesion, the lap width of adjacent strips is not less than 80 mm, and the joint is sealed by hot air welding.

[0083] Apply a waterproof coating on the surface of the waterproof coiled material. Preferably, apply the waterproof coating twice. The waterproof coating is a cement-based penetrating crystalline waterproof coating, and the thickness of each application of the waterproof coating is not less than 1.2 mm. The brushing direction of the first time and the second time are perpendicular to each other to ensure no missed coating. Cover with a wet cloth and cure for a set time. Preferably, the set time is 72 hours to promote the penetration of active substances and form crystals in the capillary pores of the concrete to block the water seepage channels.

[0084] Finally, wrap a steel plate protective layer 10 around the outer periphery of the joint part between the existing retaining wall and the connecting high retaining wall. Preferably, wrap a 3-mm-thick Q235B hot-rolled steel plate protective layer, and the steel plate protective layer is fixed on the new retaining wall formed by the existing retaining wall and the connecting high retaining wall through expansion bolts.

[0085] Step 7: Backfill the foundation trench.

[0086] In this embodiment, backfill with plain soil to the ground elevation. At this time, the construction of raising the height of the existing retaining wall is completed.

[0087] After the construction of raising the height is completed, start the construction of the new structure. First, excavate the foundation pit of the new structure. The foundation pit excavation is mainly by machinery and supplemented by manual excavation. During the construction process, the earthwork excavation uses a backhoe to relay the soil and load it onto the truck for external transportation. Along the longitudinal direction of the project, reasonably divide into several construction sections, and each section is independently excavated. According to the engineering design elevation and soil properties, divide the excavation depth into several levels and excavate layer by layer from top to bottom to reduce the disturbance range of the single excavation to the soil. At the same time, divide the excavation area into multiple small blocks from the cross-section, and excavate each block one by one according to the site conditions and the operation ability of the construction machinery.

[0088] Before the excavation, install the corresponding support structure in advance and use the support system to bear the soil pressure. After each section of excavation is in place, quickly carry out the support operation to protect the exposed soil and prevent the soil from loosening and collapsing.

[0089] In addition, during the entire construction period, with the help of monitoring equipment such as levels, parameters such as the displacement of the soil around the project, the stress of the support structure, and the groundwater level are monitored in real time, so as to ensure that the project is always in a safe and controllable state.

[0090] The above-mentioned foundation pit excavation method can adopt the existing technology and will not be described in detail here.

[0091] During the foundation pit excavation process, if there is a problem of crack water seepage caused by the damage of the diaphragm wall, leakage treatment is required, and the water seepage plugging technology can be used for treatment.

[0092] First, accurately locate the water seepage position, drill holes at appropriate positions around the crack, install diversion pipes, and lead out the seepage water through the diversion pipes to reduce the water pressure at the crack. Horizontally penetrate the diaphragm wall at the water seepage position, inject acrylate and water-absorbing resin into the crack, and use its rapid plugging characteristics to preliminarily plug the contact part between the diaphragm wall and the soil layer. After the seepage water flow gradually decreases and stops, inject cement slurry into the drilled hole position and the crack position until the pores are completely plugged.

[0093] The above-mentioned leakage treatment method can adopt the existing technology and will not be described in detail here.

[0094] The construction method of this embodiment realizes the heightening of the existing diaphragm wall, meets the requirements of the new project. When constructing the new project, it is not necessary to demolish the existing diaphragm wall, reducing the procedures of building the temporary support system and reconstructing the foundation structure, greatly reducing the repeated investment of resources, realizing the systematic optimization of the recycling rate of building materials, conforming to the concept of green construction and sustainable development. By heightening the existing diaphragm wall, the height limit of the diaphragm wall is broken through, making it applicable to complex scenarios such as ultra-deep foundation pits and underground space development, with a wider scope of application, and improving safety and environmental adaptability.

[0095] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A construction method for the reuse of the height extension of an existing diaphragm wall, characterized in that, It includes the following steps: Excavate the foundation trenches on both sides of the existing diaphragm wall. When the foundation trenches are excavated to a distance below the capping beam of the existing diaphragm wall to expose the top of the existing diaphragm wall; Detect the existing diaphragm wall and reinforce the existing diaphragm wall according to the detection results; Chisel off a part of the capping beam at the top of the existing diaphragm wall and the part at a set distance below the capping beam. Drill a plurality of pipe holes along the center line of the top surface of the existing diaphragm wall after chiseling and insert steel pipes into the pipe holes; Rebar planting is carried out on both sides of the top surface of the existing diaphragm wall after chiseling; Pour a raised diaphragm wall on the top surface of the existing diaphragm wall to form a new diaphragm wall; Conduct waterproof treatment on the joint part of the existing diaphragm wall and the raised diaphragm wall; Backfill the foundation trench.

2. The construction method for the reuse of the existing diaphragm wall by heightening according to claim 1, characterized in that, Excavate with a slope on both sides of the existing diaphragm wall according to the set slope to form a foundation trench.

3. A construction method for the reuse of the heightening of an existing diaphragm wall, as described in claim 2, wherein When excavating the foundation trench, use a multi-face and multi-layer staggered excavation method for excavation.

4. The construction method for the reuse of the existing diaphragm wall by heightening according to claim 1, characterized in that, The method for detecting the existing diaphragm wall is: Drill holes at set intervals along the extension direction of the existing diaphragm wall on both sides of the existing diaphragm wall. Then, lower a transmitting transducer and a receiving transducer into the drill holes on both sides of the existing diaphragm wall respectively. The transmitting transducer and the receiving transducer maintain the same depth, and use the transmitting transducer and the receiving transducer to detect the abnormal parts of the existing diaphragm wall.

5. A construction method for reusing the extension of an existing diaphragm wall, as described in claim 1, characterized in that, The method for reinforcing the existing diaphragm wall is: After detecting the abnormal part of the existing diaphragm wall, drill holes from the position of the top surface of the existing diaphragm wall corresponding to the abnormal part, and obtain the specific position and damage degree of the defect in the abnormal part of the existing diaphragm wall through in-hole imaging technology; Inject grout to reinforce the defect position of the existing diaphragm wall through the existing core drilling holes on the top surface of the existing diaphragm wall and / or the new drilling holes on the top surface of the existing diaphragm wall.

6. The construction method for the reuse of the existing diaphragm wall by heightening as claimed in claim 1, characterized in that, After the steel pipe is inserted into the pipe hole, the gap between the steel pipe and the hole surface of the pipe hole is filled with grouting using a slightly expanding grouting material.

7. The construction method for heightening and reusing an existing diaphragm wall according to claim 1, characterized in that The specific method for rebar planting is: Drill holes on both sides of the top surface of the existing diaphragm wall after chiseling, then inject structural adhesive into the drill holes, and then rotate the steel bars into the drill holes.

8. A construction method for the reuse of the existing diaphragm wall by heightening, as described in claim 1, wherein The pouring method for the raised diaphragm wall is: Lift the steel cage of the raised diaphragm wall to the top surface of the existing diaphragm wall after chiseling, and lap the steel cage with the steel bars of the existing diaphragm wall after chiseling; Support the formwork above the top surface of the existing diaphragm wall after chiseling, then pour concrete for the raised diaphragm wall, and cure the concrete of the raised diaphragm wall after pouring.

9. A construction method for the reuse of the extension of an existing diaphragm wall, as described in claim 1, wherein, The specific method for waterproof treatment is: Grind the surface of the joint part of the existing diaphragm wall and the raised diaphragm wall and apply a primer. Cover the joint part with a waterproof coiled material; Apply a waterproof coating on the outer surface of the waterproof coiled material; Cover a steel plate protective layer on the outer periphery of the waterproof coating, and the steel plate protective layer is fixed by expansion bolts.

10. A construction method for the reuse of the heightening of an existing diaphragm wall, as described in claim 9, wherein, The waterproof coating uses a cement-based permeable crystalline waterproof coating. After the waterproof coating is applied, cover it with a wet cloth and cure for a set time. After curing, install the steel plate protective layer.

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