Foundation pit excavation The foundation pit of bearing platform shall be excavated manually with excavator, and the bottom shall be cleaned and the pile head shall be chiseled manually
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The step ladder is assembled, customized and equipped with handrails
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The reinforcement cage orifice shall be extended by single-sided lap welding, the weld length shall not be less than 10d, and the joint reinforcement must be pre bent
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The protective fence shall be installed on the top of the retaining dam, and the distance between the protective fence and the edge of the foundation pit shall not be less than 0.5m
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Sump and drainage ditch shall be set in the pit（ This standard is applicable to ordinary foundation pit, and the construction of special foundation pit shall be carried out according to the corresponding special scheme) • the foundation pit of bearing platform shall be fully enclosed by fence, hung with dense mesh net, and provided with openings and steps (including handrails)
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2、 • bearing platform 1
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Mud pit protection: customized protective railings are used around the mud pit
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The comprehensive grounding reinforcement must be identified and accurately butted
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The size of the mud pit is the same as that of the above
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When the reinforcement cage is lowered, clean water shall be injected into the pipe in time
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2
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• The process test shall be carried out for the first pouring body of mass concrete, and the key temperature monitoring shall be carried out for the structure in the initial construction.
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The concrete shall be poured in layers and vibrated tightly with an immersion vibrator
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Drilling • Drilling rig in place: check the site and the installation of main machines and tools of the drilling rig, and prepare to start drilling only after the perpendicularity and center position of the drill bit and drill pipe meet the requirements
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After setting out, the protective pile shall be inserted and driven, and the protective pile shall be firm, stable and protected
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• Mud consists of water, clay (or bentonite) and additives
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The reinforcement cage shall be hoisted by crane with double lifting points, and the reinforcement cage shall not be dragged to the ground
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Click the blue words above to pay attention to us I
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The foam tube can insulate the bond between steel bar and concrete, facilitate the peeling of concrete and steel bar, reduce the mechanical damage to the steel bar when breaking the pile head, but the position should be strictly controlled in the construction process
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Pile casing embedding The top surface of pile casing shall be 2m higher than the construction water level or groundwater level and 0.5m higher than the construction ground
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• The embedded reinforcement of pier body shall be installed with positioning fixture
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It is strictly prohibited to put it directly on the ground
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The key points of management shall be implemented in strict accordance with the approved construction scheme and technical disclosure, and the management shall be implemented according to the division of responsibilities
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The total station or GPSRTK with 2 “accuracy shall be used for construction setting out, and the S3 level shall be used for elevation measurement
• For mass concrete construction, the cooling pipe shall be buried according to the design requirements during reinforcement processing and installation
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3
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The slurry exchange method is adopted for hole cleaning to maintain the water head in the hole and prevent hole collapse and necking
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After hole cleaning and before grouting, various indexes of mud shall be tested respectively
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The handrails are painted with red and white paint and can be reused
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The slope surface shall be protected with plastic cloth inside the mud pit
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Set shaped steel formwork shall be adopted for firm reinforcement
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After the reinforcement cage is lowered, it is cross supported on the sleeper (220 * 160 * 2600mm) outside the orifice to ensure the stable installation of the reinforcement cage
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• Alignment: after the drilling rig is in place, use the retaining pile to restore the pile position center, and manually cooperate with the mechanical drill bit to align the pile center with a deviation of no more than 5cm
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Each bored cast-in-place pile shall be provided with an acoustic pipe according to the design requirements
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Before the commencement of construction preparation, complete the “three supplies and one leveling”, review of design documents, raw materials and their tests, equipment selection, labor organization, commencement report, etc
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The drilling equipment shall be reasonably selected according to the geological conditions and progress of the construction site, and the rotary drilling rig and circulating drilling rig shall be preferred
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The first batch of concrete pouring must ensure that the buried depth of the conduit is more than 1m, and the first batch of concrete hopper must meet the back sealing requirements
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The requirements are as follows: 6
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The pile casing is buried vertically
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8
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Standard curing test pieces: for every 100 discs of concrete mixed and no more than 100 cubic meters of the same part of the project, sampling shall not be less than once, and at least one group of test pieces shall be reserved for each sampling
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• After the hole inspection, the reinforcement cage shall be lowered
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3
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During the pouring process, the elevation of the concrete surface shall be measured in time with measuring rope and hammer meeting the specification requirements
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The clayey soil filled at the bottom and around must be compacted in layers, and the top is strictly prohibited from bearing load
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• hole finishing, hole cleaning and inspection After the drilling reaches the design elevation and hole position, the hole depth, hole diameter, hole position, hole shape and hole bottom geology shall be inspected
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The wall thickness and other indicators of the acoustic pipe shall meet the design requirements
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During installation, measures shall be taken to firmly fix it with the reinforcement cage
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• drilling: after the prepared mud is injected into the hole, the bit starts to run slowly During drilling, the specific gravity of mud shall be detected at any time, and the drilling slag sample shall be reserved according to the design requirements
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• concrete pouring and curing The formwork shall meet the requirements of structural strength, stiffness and stability
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When the reinforcement cage is processed, the steel bar extending into the bearing platform is covered with a 1cm thick foam tube slightly larger than the main reinforcement diameter of the reinforcing cage and secured by wire binding
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Concrete pouring • After the drilling reaches the design elevation and hole position, the hole depth, hole diameter, hole position, hole shape and hole bottom geology shall be inspected
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After the reinforcement cage is lowered, the tremie shall be lowered section by section, and the distance from the lower opening of the tremie to the hole bottom shall be 25cm ~ 40cm
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Storage of reinforcement cage for acoustic pipe installation (socket threaded interface): use [14 channel steel to weld the storage rack shown in the figure (the figure shows the pile foundation with a diameter of 1m)
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• Construction setting out: the survey team shall set out the central pile position, hand over the pile to the on-site technicians, and protect the pile position; • Pile casing embedding: field technicians shall recheck the pile casing embedding position and deviation; • Mud preparation: the on-site test personnel shall detect the mud index; • Pile foundation drilling: field technicians check the bit alignment and mechanical stability; • Pile foundation drilling: the technician of the first pile of each bearing platform shall witness and take slag samples; • Final hole inspection: under the guidance of on-site technical or safety and quality personnel, use hole detector for final hole inspection, and report to the supervisor for inspection after passing the inspection; • Reinforcement cage: the on-site technical or safety and quality personnel shall conduct delivery inspection and on-site orifice connection inspection, and report to the supervisor for inspection after passing the inspection Pile foundation pouring: the field test personnel shall detect various properties of concrete and make test pieces, and the field technical personnel shall guide the whole process of pouring
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During foundation pit excavation, a 20cm high water retaining platform shall be set outside the excavation line to prevent surface water from flowing into the foundation pit
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For permeable strata such as sandy soil and silt, replace with clay to the foot of the pile casing edge not less than 0.5m, the pile casing diameter is 20 ~ 30cm larger than the design pile diameter, the length is generally not less than 2m, and the wall thickness is not less than 10mm
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bored pile 1
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After the finished reinforcement cage passes the inspection, fill in the finished pile foundation reinforcement cage signboard, which adopts 40cm wide and 30cm high car sticker + iron sheet
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If it cannot be connected, it shall be removed and placed again
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The slurry exchange method is adopted for hole cleaning to maintain the water head in the hole and prevent hole collapse and necking
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2
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7
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The specific gravity of mud in cohesive soil layer is 1.05 ~ 1.20, and the viscosity is 16S ~ 22s; The specific gravity of mud in sandy soil layer is 1.20 ~ 1.45 and the viscosity is 19S ~ 28s
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The corresponding joints of adjacent sections shall be marked
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After the installation of mud pit fence, install night warning lights at four corners, which are powered by LED dry battery
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Remarks on mud preparation: the above figure shows the standard for setting the mud pit of rotary drilling rig, and the mud pit of rotary drilling rig is set as one mud pit at each two pier positions
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The protective railings are assembled, with a vertical pole height of 1.5m and a mesh size of 1.2m × The width is 2.0m, and the surface is painted with red and white paint
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During concrete pouring, filter screen shall be used to filter the concrete to prevent large blocks of concrete from blocking the conduit
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In order to ensure the overall stiffness of the bearing platform framework, positioning support shall be set
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The concrete pouring of ordinary bearing platform adopts chute into the formwork; When the concrete truck cannot reach the feeding port directly, the truck pump can be used to pour concrete
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The joint connection shall be well sealed, and the top shall be blocked with a rubber cover
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Reinforcement processing and installation • The reinforcement is intensively processed and manufactured in the reinforcement processing workshop, transported to the site by flat truck, and accurately set out and positioned and bound on site after the base is inspected to be qualified
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After installation, the measuring rope shall be lowered in time to detect whether the acoustic measuring pipe is connected
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The reinforcement cage is temporarily placed on the storage rack according to the specified area on site and covered with colored strip cloth
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The bottom of the acoustic pipe shall be welded and blocked when leaving the factory
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4
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Fabrication and installation of reinforcement cage • The reinforcement cage is processed and manufactured by automatic roll welding machine in the reinforcement processing plant
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