Prefabricated formwork installation method of deep bearing platform

Abstract

A prefabricated formwork installation method for a deep bearing platform is suitable for the bearing platform with the depth of 1800-3400 mm and is characterized by comprising the following steps of a, bearing platform bottom cushion layer cleaning, b, earth excavation, c, sample trial placement and prefabricated formwork cutting and blanking, d, bedding and prefabricated formwork splicing, e, re-checking and correcting, f, splicing seam reinforcing, g, corner base repairing and reinforcing, h, inner support reinforcing, i, earth backfilling and j, bearing platform peripheral bottom plate cushion layer pouring. K, dismantling the inner supporting frame body; and l, constructing a subsequent working procedure. The mounting method for the prefabricated formwork of the deep bearing platform has the advantages that the technical measure of 3 + 2 + 1 is adopted, the using amount of the prefabricated formwork is reduced, the rigidity of the formwork is effectively guaranteed, deformation and displacement of the formwork in the earthwork backfilling stage are avoided, the construction progress is accelerated, the construction quality is guaranteed, and the cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of building engineering, and in particular relates to a method for installing a prefabricated template of a deep cap. Background Art

[0002] With the development of construction technology and prefabricated construction, prefabricated formwork and prefabricated pedestal formwork are generally made of fine aggregate cement hollow prefabricated board membrane. They are formed by mixing fly ash, cement and construction debris evenly and then extruding them uniformly in a production machine. They have good integrity and are a green building material that reuses construction debris.

[0003] Figure 1 The following is a schematic diagram of the precast formwork structure of a known foundation. The commonly used precast formwork dimensions are 90mm thick and 600mm wide. However, the precast formwork with a length of 2000mm-3200mm cannot be produced in fixed lengths in combination with the foundation dimensions on site. Traditionally, brick formwork is used to build foundations on site. Some projects have begun to use new precast formwork. However, for foundations with greater depth, the precast formwork of the deep foundation is prone to deformation and displacement during the backfilling stage, and the rigidity is insufficient.

[0004] Therefore, the known prefabricated formwork configuration method of the deep cap has the above-mentioned inconveniences and problems. Summary of the invention

[0005] The purpose of the present invention is to provide a safe and reliable method for installing a prefabricated formwork for a deep bearing platform.

[0006] To achieve the above purpose, the technical solution of the present invention is: A method for installing a prefabricated formwork for a deep cap, suitable for caps with a depth of 1800-3400 mm, is characterized by comprising the following steps: a. Cleaning of the bottom cushion of the pedestal Thoroughly clean the cushion surface of the prefabricated formwork for the installation of the foundation to ensure that the surface of the concrete structure of the cushion layer in contact with the wall panels is flat, the structure is dense, and the strength meets the conditions for human operation; b. Earthwork excavation During the earthwork excavation phase, the surveyor shall provide technical guidance to the earthwork unit, and over-excavation and random excavation are strictly prohibited; c. Trial sample placement and prefabricated template cutting According to the height of the pedestal and the ground beam, combined with the width of the wall panel, the prefabricated template is cut and blanked. The size of the part that needs to be connected with the prefabricated template should be measured in advance to avoid material waste; d. Prefabricated formwork When installing the precast formwork, the top and side edges of the precast formwork shall be coated with adhesive evenly; when erecting the wall precast formwork, use a crowbar to squeeze it tightly into place, and at the same time use a three-line laser level to correct the verticality and the flatness of the adjacent precast formwork surfaces in a timely manner to ensure that the joints are closely combined and straight; e. Recheck and correct For the operation of assembling precast formwork at the parts with large elevation errors of the cushion layer, use wooden wedges to tightly support at the bottom of the precast formwork in a timely manner, and the adhesive extruded at the joint parts shall be scraped and filled in a timely manner; when installing the precast formwork of the bearing platform, the top height of the precast formwork shall be controlled by the bottom height of the cushion layer, and the error shall not be greater than 30 mm; f. Joint reinforcement After the installation of the precast formwork is completed, use adhesive to fill and plaster the joints in a timely manner, and cover with grid tape. For the inner and outer corner parts, use secondary grouting for repair and reinforcement to ensure that the inner and outer corners are square and improve the integrity of the precast formwork of the bearing platform; g. Repair and reinforcement of the corner base Strengthen the quality self-inspection of the bottom of the precast formwork. After the work of assembling the precast formwork is completed, clean the floor ash at the bottom in a timely manner, and use secondary grouting to repair the joint parts of 50 mm at the bottom of the cushion precast formwork and 50 mm on the vertical surface of the precast formwork. After the operation is completed, clean the surface of the cushion layer in a timely manner; h. Inner support reinforcement After the installation model of the precast formwork is completed, recheck the data of the top elevation of the precast formwork, the inner empty size of the bearing platform formwork, the squareness of the inner and outer corners, the flatness of the plate joints and the verticality of the plates. After passing the acceptance, use steel pipes and wooden squares for inner support reinforcement in a timely manner. The spacing of the reinforcement inner supports shall not be greater than 3 m, and add supports at the joints; i. Earthwork backfilling The backfill construction shall be carried out 8 hours after the installation of the precast formwork of the bearing platform is completed. The soil shall slide slowly from the slope into the side of the precast formwork of the bearing platform, and be backfilled simultaneously around, and leveled manually. After the earthwork of the precast formwork of the bearing platform is backfilled, no large machinery shall go up for operation to reduce the extrusion damage to the bearing platform formwork; j. Pouring the bottom slab cushion of the periphery of the bearing platform After the earthwork backfilling is completed, pour the concrete of the bottom slab cushion according to the design elevation to ensure that the concrete of the bottom slab cushion completely covers the bearing platform formwork to improve the effective connection integrity between the cushion layer and the bearing platform formwork; k. Removal of the inner support frame The inner support shall be removed 8 hours after the installation of the precast formwork of the bearing platform is completed and after the earthwork backfilling is completed and the bottom slab cushion has solidified; l. Construction of subsequent processes Start the construction of waterproofing and subsequent processes.

[0007] The installation method of the precast formwork of the deep bearing platform of the present invention can also be further realized by adopting the following technical measures.

[0008] The foregoing method, wherein the binder is hydroxypropyl methylcellulose.

[0009] The foregoing method, wherein the scraping thickness of the binder is not less than 30 mm.

[0010] The foregoing method, wherein the support at the joint is a 50x100 mm wooden square or a standard steel pipe inclined support.

[0011] After adopting the above technical solution, the precast formwork installation method of the deep foundation cap of the present invention has the following advantages: 1. Adopting the technical measures of "3+2+1" can save the consumption of precast formwork, effectively ensure the stiffness of the formwork, and avoid the deformation and displacement of the formwork during the earthwork backfilling stage; 2. Improve the construction progress, ensure the construction quality, and reduce the cost. Description of the Drawings

[0012] Figure 1 It is a schematic structural diagram of the precast formwork of a known foundation cap; Figure 2 It is a plan view of the 1800-3400 precast formwork of the embodiment of the present invention; Figure 3 It is a plan view of the deep bottom layer structure of the 1800-3400 of the embodiment of the present invention; Figure 4 It is a deep middle layer structure diagram of 1800~3400 of the embodiment of the present invention; Figure 5 It is a deep top layer structure diagram of 1800~3400 of the embodiment of the present invention; Figure 6 It is Figure 2 A cross-sectional view taken along A-A in Detailed Embodiments

[0013] The present invention will be further described below in conjunction with the embodiments and their accompanying drawings.

[0014] Embodiment 1 Now please refer to Figure 2-6 , the precast formwork installation method of the deep foundation cap of the present invention is applicable to the foundation cap with a depth of 1800-3400 mm and includes the following steps: 1. Cleaning of the bottom cushion of the foundation cap The cushion surface where the precast slab foundation cap formwork is to be installed must be thoroughly cleaned. It is necessary to ensure that the surface of the cushion concrete structure in contact with the wall panel is flat, the structure is dense, and the strength meets the conditions for personnel operation. At the same time, there should be no obvious water accumulation in the working surface area, and operations should be avoided in rainy days.

[0015] 2. Earthwork excavation During the earthwork excavation stage, full-time surveyors should be assigned to provide technical guidance to the earthwork contractors, and over-excavation and random excavation are strictly prohibited.

[0016] 3. Trial layout and cutting of plates According to the heights of the pile caps and ground beams, combined with the width of the wall panels (standard panel width is 600mm), cut the plates. For the parts that need to be spliced, measure the dimensions in advance to avoid waste of materials. The formwork is a 90mm thick precast pile cap formwork.

[0017] 4. Grouting and panel splicing When installing the plates, the top and side edges should be coated with adhesive evenly. Name of adhesive: Hydroxypropyl Methylcellulose; Adhesive strength: 148,000 Mpa. The coating should be uniform without dripping, and the scraping thickness of the adhesive should not be less than 30mm. When erecting the wall panels, use a crowbar to squeeze them tightly into place, and at the same time use a three-line laser level to correct the verticality and the flatness of adjacent panel surfaces in a timely manner to ensure that the joints are closely combined and straight.

[0018] 5. Recheck and correction For the panel splicing operation at the parts with large elevation errors of the cushion, use wooden wedges to tightly support from the bottom of the plate in a timely manner, and scrape and fill the adhesive extruded at the gap part in a timely manner.

[0019] After the wall panels are initially in place, use a square and a plumb bob to level and straighten the wall surface in a timely manner.

[0020] When installing the precast plate pile cap formwork, the top height of the plate is controlled by the bottom height of the cushion, and the error shall not be greater than 30mm.

[0021] 6. Joint reinforcement After the plate installation is completed, use adhesive to fill and scrape the joints in a timely manner, and cover with a mesh tape to improve the integrity of the joints. For the parts such as internal and external corners, secondary grouting repair and reinforcement treatment should be carried out to ensure that the internal and external corners are square and at the same time improve the integrity of the pile cap formwork.

[0022] 7. Repair and reinforcement of the bottom and corner bases For the bottom part, quality self-inspection should be strengthened. After the panel splicing work is completed, clean the bottom floor ash in a timely manner. At the same time, carry out secondary grouting repair for the 50mm joint part at the bottom of the cushion and the 50mm vertical surface of the plate. After the operation is completed, clean the surface of the cushion in a timely manner to make preparations for the subsequent operations in advance.

[0023] 8. Internal support reinforcement After the installation of the model is completed, key data such as the elevation of the top of the slab, the internal dimension of the pile cap formwork, the squareness of the internal and external corners, the flatness of the plate joints, and the perpendicularity of the plates shall be rechecked. After passing the acceptance, internal bracing shall be promptly carried out using steel pipes and wooden squares. The spacing of the internal bracing shall not be greater than 3m, and additional supports shall be appropriately added at the joints. For the supports at the joints, 40mm*90mm wooden squares shall be used as internal supports, or standard Φ48*3.6mm galvanized steel pipes can also be used as internal supports.

[0024] 9. Earth backfilling 8 hours after the installation of the precast pile cap formwork is completed (when the adhesive strength reaches the maximum value and meets the stress requirements, the construction of backfill soil can be carried out), attention shall be paid to avoiding directly applying force to squeeze the soil with the pile cap formwork as the stress fulcrum, and especially avoiding the impact of the hopper for transporting soil on the formed precast pile cap formwork. The soil shall slowly slide down from the slope to the edge of the precast pile cap formwork, and backfill shall be carried out simultaneously around, and manual leveling shall be coordinated. After the earth backfilling of the precast pile cap formwork, large machinery shall not be allowed to operate on it to reduce the extrusion damage to the pile cap formwork.

[0025] 10. Pouring of the bottom slab cushion outside the pile cap After the earth backfilling is completed, the bottom slab cushion concrete shall be poured according to the design elevation to ensure the overall coverage of the bottom slab cushion concrete on the pile cap formwork, so as to improve the effective connection integrity between the cushion and the pile cap formwork.

[0026] 11. Removal of the internal bracing frame The internal bracing shall be removed 8 hours after the installation of the precast pile cap formwork is completed (when the adhesive strength reaches the maximum value and meets the stress requirements) and after the earth backfilling is completed and the bottom slab cushion has solidified.

[0027] 12. Construction of subsequent processes The present invention has substantial features and remarkable technical progress. The method for installing precast formwork for deep pile caps of the present invention is applicable to the assembly of precast formwork for pile caps, sumps, etc. in basements with a pile cap depth of 1800mm - 3400mm. Compared with the traditional method, the construction is more convenient, with fewer processes, saving construction period and having better economy. In the early stage, brick formwork was used for construction in parts where it was not easy to remove the formwork on the side walls of basement foundation beams, pile caps, sumps, etc. However, the construction period of brick formwork masonry is long, the labor input is large, and there are many objective factors affecting the project, making it difficult to control the construction period and cost. In order to improve the construction efficiency of pile cap formwork, in some parts of the basement floor beams, pile caps, sumps, etc. of the basement, the practice of using precast plates as precast formwork for pile caps has emerged. However, for areas with a relatively large pile cap depth, due to the relatively large lateral pressure of the backfill construction soil, there are prone to problems such as insufficient stiffness, deformation and displacement, and it is impossible to ensure the construction dimensions and safety of the pile cap. The construction method of the precast formwork for pile caps with a depth of 1800 - 3400mm of the present invention can not only ensure the construction efficiency of the precast formwork, but also well ensure the formwork stiffness.

[0028] Adopt the "3 + 2 + 1" method from the bottom layer to the top layer, that is, set 3 layers of precast slabs at the bottom layer, set 2 layers of precast slabs in the middle layers, and set 1 layer of precast slabs at the top layer. Through mortar bedding and panel splicing and end-to-end mutual support, it effectively saves the consumption of precast templates, effectively ensures the stiffness of the templates, and avoids the deformation and displacement of the templates during the earthwork backfilling stage. It improves the construction progress, and also ensures the construction quality and reduces the cost.

[0029] The precast formwork installation method for deep caissons of the present invention has been actually applied in the Guangzhou Convention and Exhibition Center project. The ground floor area of the project is 68,000 square meters. The construction is simple and has fewer processes, and the cost is more economical. Through the "3 + 2 + 1" structural practice, it effectively ensures the strength, stiffness and stability of the precast formwork installation for caissons with a depth of 1800 mm to 3400 mm. The appearance quality is good, the applicable range is wide, it is easy to master, and it is easy to promote and use. It has been unanimously recognized by the supervision unit and the construction unit, welcomed by the operators, and achieved good economic benefits and social impacts.

[0030] The above embodiments are only for illustrating the present invention, rather than limiting the present invention. Those skilled in the relevant technical fields can also make various transformations or changes without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should also belong to the scope of the present invention and should be defined by each claim.

Claims

1. A method for installing a prefabricated formwork for a deep cap, suitable for caps with a depth of 1800-3400 mm, characterized in that The following steps are involved: a. Cleaning of the bottom cushion of the pedestal Thoroughly clean the cushion surface of the prefabricated formwork for the installation of the foundation to ensure that the surface of the concrete structure of the cushion layer in contact with the wall panels is flat, the structure is dense, and the strength meets the conditions for human operation; b. Earthwork excavation During the earthwork excavation phase, the surveyor shall provide technical guidance to the earthwork unit, and over-excavation and random excavation are strictly prohibited; c. Trial sample placement and prefabricated template cutting According to the height of the pedestal and the ground beam, combined with the width of the wall panel, the prefabricated template is cut and blanked. The size of the part that needs to be connected with the prefabricated template should be measured in advance to avoid material waste; d. Prefabricated formwork When installing the prefabricated formwork, the top and side edges of the prefabricated formwork should be fully coated with adhesive, and the adhesive should be evenly applied; when the wall prefabricated formwork is erected, it should be squeezed tightly into place with a crowbar, and the verticality and the flatness of the adjacent prefabricated formwork surfaces should be corrected in time with a laser three-line instrument to ensure that the joints are tight and straight; e. Review and Correction For the prefabricated formwork work in the part with large cushion elevation error, wooden wedges should be used to tighten the bottom of the prefabricated formwork in time, and the adhesive squeezed out of the gap should be scraped and filled in time; when the prefabricated formwork of the pedestal is installed, the height of the top of the prefabricated formwork is controlled by the height of the cushion bottom, and the error shall not exceed 30mm; f. Seam reinforcement After the prefabricated formwork is installed, adhesive is used to fill the joints and slurry is applied in time, and the mesh tape is covered. For the inner and outer corners, secondary grouting repair and reinforcement treatment is used to ensure that the inner and outer corners are square and improve the integrity of the prefabricated formwork of the foundation; g. Repair and strengthen the corner base Strengthen the quality self-inspection of the bottom of the prefabricated formwork, clean the dust on the bottom in time after the prefabricated formwork is assembled, and repair the joints of the 50mm prefabricated formwork on the cushion layer and the 50mm joints on the facade of the prefabricated formwork for the second time. Clean the cushion layer surface in time after the work is completed; h. Internal support reinforcement After the prefabricated formwork installation model is completed, the prefabricated formwork top elevation, the size of the space inside the pedestal formwork, the squareness of the inner and outer corners, the flatness of the plate joints and the verticality of the plate are reviewed. After acceptance, steel pipes and wooden squares are used for internal support reinforcement in a timely manner. The spacing between the reinforced internal supports shall not be greater than 3m, and additional support is provided at the joints. i. Backfill The backfilling construction is carried out 8 hours after the installation of the prefabricated formwork of the cap is completed. The soil will slowly slide down from the slope to the edge of the prefabricated formwork of the cap, and the surrounding areas will be backfilled at the same time, and manual leveling will be carried out. After the backfilling of the prefabricated formwork of the cap, no large machinery shall be used to operate in order to reduce the extrusion and damage to the cap formwork; j. Casting of the outer bottom slab cushion layer of the pedestal After the earthwork is backfilled, pour the bottom slab cushion concrete according to the designed elevation to ensure that the bottom slab cushion concrete covers the entire cap formwork to improve the effective connection integrity between the cushion and the cap formwork; k. Dismantling of the inner support frame The internal support should be removed 8 hours after the installation of the prefabricated formwork of the foundation, and after the earth backfill is completed and the bottom plate cushion layer solidifies; l. Construction of post-process Waterproofing and post-process construction began.

2. The method for installing a prefabricated formwork for a deep cap according to claim 1, characterized in that: The binder is hydroxypropyl methylcellulose.

3. The method for installing a prefabricated formwork for a deep cap according to claim 1, characterized in that: The coating thickness of the adhesive shall not be less than 30 mm.

4. The method for installing a prefabricated formwork for a deep cap according to claim 1, characterized in that: The support at the joints is made of 50x100mm wooden squares or standard steel pipe diagonal braces.

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