CN115977134B - Pile-anchor combined foundation structure construction method - Google Patents
Pile-anchor combined foundation structure construction method Download PDFInfo
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- Piles And Underground Anchors (AREA)
Abstract
The invention discloses a construction method of a pile-anchor combined foundation structure, which comprises a plurality of pile foundations, wherein foundation platforms used for bearing an L-shaped water tank are poured on the pile foundations, the foundation platforms are poured in three layers, a plurality of prestressed anchor cables used for tensioning and anchoring the foundation structure are arranged on the foundation platforms, and a fixed support and a sliding support used for fixing the L-shaped water tank are further arranged on the foundation platforms. According to the method, the foundation platform 2 is borne by the pile foundations 1, the foundation platform 2 is anchored by the prestress anchor cables 3, so that the foundation structure can resist high-energy pulse horizontal impact load, meanwhile, the integral sedimentation difference and the uneven sedimentation difference meet the use requirements, the L-shaped water tank in full load can be borne, strong recoil force generated when the L-shaped water tank emits high-speed water flow can be resisted, and the structure is kept stable.
Description
Technical Field
The invention relates to the technical field of pile cap foundation structure construction, in particular to a pile-anchor combined foundation structure construction method.
Background
The large aircraft ground dynamics test platform is an internationally leading and domestic unique test platform which is used for testing the high-speed dynamics characteristics of various aircraft tires, wheel brakes and landing gear systems under different road surfaces and the large slip angle dynamics characteristics under a real runway after the NASA test base, basic data are collected, monopoly of key technical basic data is broken through abroad, domestic blank is filled, the test platform adopts an L-shaped water tank driving system, a water tank can generate strong horizontal reverse impulsive force when high-speed water flow is emitted, impact is caused on a bearing platform basic structure below the water tank, stability of the structure is affected, the horizontal reverse impulsive force generated by the water tank driving system cannot be resisted by the current construction scheme of the bearing platform basic structure, structural instability is caused, and the integral sedimentation difference of the bearing platform basic structure cannot be ensured to be in a controllable range.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects of the prior art and providing a pile-anchor combined foundation structure construction method capable of guaranteeing stable structure.
In order to solve the technical problems, the invention adopts the following technical scheme:
the foundation structure comprises a plurality of pile foundations, a foundation platform used for bearing an L-shaped water tank is poured on the pile foundations, a plurality of prestressed anchor cables used for tensioning and anchoring the foundation structure are arranged on the foundation platform, a fixed support and a sliding support used for fixing the L-shaped water tank are further arranged on the foundation platform, and the foundation platform is poured in three layers; the construction method comprises the following steps:
S1: pouring pile foundation; the method comprises the steps of leveling a site before construction, accurately positioning the center of the site by using a total station according to pile foundation coordinates, arranging a cross pile protector outside a range of 1.5m, burying a steel pile protector in the center of the pile foundation, drilling by adopting a drilling machine, cleaning holes after hole forming, changing slurry, installing a reinforcement cage after the pile foundation holes are inspected to be qualified, arranging a guide pipe, and directly pouring and forming by adopting a concrete tank truck.
S2: arranging and constructing a prestressed anchor cable; firstly, digging a foundation pit by using an excavator, making a drainage ditch, leveling the ground, laying out the foundation ditch point by point according to the design coordinates of the hole sites, marking, drilling by using a drilling machine, cleaning after the anchor holes are formed, immediately installing a prestressed anchor cable hole after the anchor holes are inspected to be qualified, and grouting in time after the anchor holes are stabilized.
S3: pouring a cushion layer; firstly, setting out a foundation sideline, digging a foundation pit by adopting manual cooperation with machinery, then, performing concrete breaking on a pile foundation supergrouting part, adjusting a reinforcement cage to a position required by design, cleaning a pile head, setting out a bedding sideline control point by adopting a total station, measuring the elevation by adopting a level gauge, cleaning, compacting and leveling the foundation, installing a template, and performing concrete pouring by adopting an automobile crane batching hopper.
S4: pouring a first layer of concrete of the foundation table; firstly, setting out the side line and the central line, measuring the elevation, binding the steel bars, installing the template, embedding the protective sleeve of the prestressed anchor cable, and pouring concrete.
S5: constructing anchor piers and tensioning and locking prestressed anchor cables; and after the first layer of concrete of the foundation platform reaches the design strength, pouring anchor pier concrete on the concrete surface, lengthening the prestressed anchor cable protective sleeve to an anchor backing plate before pouring, tensioning and locking the prestressed anchor cable after the anchor pier concrete reaches the design strength, and then sealing the anchor, wherein the prestressed anchor cable on the outermost layer of the foundation structure is reserved on the second layer of foundation platform for tensioning and sealing the anchor after pouring.
S6: pouring a second layer of concrete of the foundation platform; binding reinforcing steel bars, installing templates, pre-burying a pre-stressed anchor cable protective sleeve, and then pouring concrete.
S7: constructing an anchor pier of the prestressed anchor cable at the uppermost layer and tensioning and sealing the anchor; and after the second layer of concrete of the foundation platform reaches the design strength, pouring the outermost layer of prestressed anchor cable anchor pier on the concrete surface, lengthening the prestressed anchor cable protective sleeve to an anchor backing plate before pouring, tensioning and locking the prestressed anchor cable after the anchor pier concrete reaches the design strength, and then sealing the anchor.
S8: pouring concrete of a third layer of the foundation table; binding reinforcing steel bars, installing corrugated pipes on the reinforcing steel bars as drainage pipes, installing templates, hoisting fixed supports and sliding supports, and then performing concrete casting to reserve a pipe ditch.
As a further improvement of the above technical scheme:
in step S1, a slurry tank for preparing and storing fresh slurry is provided, the fresh slurry flows into the pile foundation hole by self weight during drilling, and the slurry mixed with drilling slag is pumped to a sedimentation tank by a slurry pump.
The pile foundation is poured by concrete with the strength of C30, and is constructed by adopting a waterproof ball conduit method during pouring.
In the step S2, the inclination angle between the prestressed anchor cable and the horizontal plane is 30 degrees, the single prestressed anchor cable is formed by adopting 3 phi S15.2 steel strands as a bundle, a grouting pipe is arranged, the free section of the prestressed anchor cable is firstly derusted and painted with rust-proof paint, then is coated with dehydrated butter, then is sheathed with a plastic sleeve and is tightly bound by lead wires, and the adhesive tape is wound at the boundary part of the free section and the anchoring section for fixedly connecting and sealing treatment.
The anchor hole drilling mode adopts a water drill, a steel pipe is followed during drilling, the anchoring grouting adopts a secondary grouting method, primary normal pressure grouting and secondary splitting grouting, wherein the pressure of the secondary splitting grouting is controlled between 2.5 MPa and 4.0MPa, and the cement slurry ratio is cement: water = 1:0.42.
In step S5, the designed axial tension value nt=300 kN of the prestressed anchor cable, the prestressed anchor cable is stretched for 1-2 times according to 20% axial force standard before the main stretching of the prestressed anchor cable, the main stretching and locking of the prestressed anchor cable of the same line are performed according to odd or even staggered stretching, the main stretching and locking of the prestressed anchor cable are performed in stages, after the anchor cable is stretched to 1.1-1.2 times of designed anchoring force, the anchor cable is kept for 15min, and then is unloaded to the designed anchoring force and locked, and after the stretching is completed for 6-10 d, the compensation stretching is performed again, and then the locking is performed.
And rust removal is carried out on the anchor head during anchor sealing, the anchor is covered by adopting subsequent upper layer concrete pouring after three times of anti-corrosion paint are coated, and the anchor sealing concrete is not independently poured.
In the steps S4, S6 and S7, the first layer of concrete template of the foundation platform adopts a brick die, the second layer and the third layer adopt a shaping steel template, temperature measuring elements are pre-embedded in the concrete of the foundation platform of the three layers respectively, the concrete of the foundation platform of each layer is poured in batches and tamped in batches, the pouring thickness of each batch is 300-400 mm, the pouring interval time is longer than 4h and is not longer than the initial setting time, and the free falling height of the concrete from the high position is less than 2m.
The concrete is vibrated by adopting a phi 50mm inserted vibrating rod, the vibrating rod moves by adopting a determinant, the moving distance is not more than 400mm, the lower batch of concrete is inserted for 50-100 mm when the upper batch of concrete is vibrated, the heat preservation and the coverage are timely carried out after the concrete of each layer of foundation platform is removed, the two sides are wrapped by permeable geotextile closely attached to the concrete surface, and the sprinkling is carried out for keeping moist.
The temperature of the concrete in the mold is controlled to be 5-30 ℃, the temperature difference between the center and the surface of the concrete is not more than 25 ℃, the temperature difference between the surface temperature and the atmosphere is not more than 20 ℃ when the heat preservation cover is removed from the surface of the concrete casting body, the temperature rise value of the concrete casting body on the basis of the temperature of the concrete in the mold is not more than 50 ℃, and the cooling rate of the concrete casting body is not more than 2 ℃/d.
Compared with the prior art, the invention has the advantages that:
According to the pile-anchor combined foundation structure construction method, the pile foundation platforms bear the foundation, so that the bearing capacity of the foundation structure meets the requirement, an L-shaped water tank driving system in full load can be borne, meanwhile, the foundation platforms are anchored by the aid of the plurality of prestressed anchor cables, the foundation platforms are divided into multiple layers to be poured, reliable anchoring of the prestressed anchor cables is achieved, high-energy pulse horizontal impact load generated by the L-shaped water tank is resisted, the stability of the structure is maintained, and the integral sedimentation difference and the uneven sedimentation difference of the foundation structure meet the use requirement.
Drawings
Fig. 1 is a construction flow chart of the present invention.
Fig. 2 is a schematic diagram of the basic structure of the L-shaped tank driving system in the present invention.
The reference numerals in the drawings denote:
1. Pile foundation; 2. a base station; 3. and (5) an anchor rope.
Detailed Description
The invention will be described in further detail with reference to the drawings and the specific examples.
As shown in fig. 1 and 2, in the pile-anchor combined foundation structure construction method of the embodiment, the foundation structure includes a plurality of pile foundations 1, a foundation platform 2 for bearing an L-shaped water tank is poured on the pile foundations 1, a plurality of prestressed anchor cables 3 for tensioning and anchoring the foundation structure are arranged on the foundation platform 2, a fixed support and a sliding support for fixing the L-shaped water tank are further arranged on the foundation platform 2, and the foundation platform 2 is poured in three layers; the construction method comprises the following steps:
S1: pouring pile foundation 1; leveling the site before construction, accurately positioning the center of the pile foundation by using a total station according to the coordinates of the pile foundation 1, arranging a cross pile protector outside a range of 1.5m, burying a steel pile protector in the center of the pile foundation 1, drilling by using a drilling machine, cleaning holes after hole forming, changing slurry, installing a reinforcement cage after the pile foundation holes are inspected to be qualified, arranging a guide pipe, and directly pouring and forming by using a concrete tank truck;
s2: the prestressed anchor cable 3 is arranged and constructed; digging a foundation pit by using an excavator, making a drainage ditch, leveling the ground, laying out points by points according to the design coordinates of hole sites, marking, drilling by using a drilling machine, cleaning after forming an anchor hole, immediately installing a prestressed anchor cable 3 into the hole after the anchor hole is inspected to be qualified, and grouting in time after stabilizing;
S3: pouring a cushion layer; firstly, setting out a foundation sideline, digging a foundation pit by adopting manual cooperation with a machine, then, performing concrete breaking on an overcast part of a pile foundation 1, adjusting a reinforcement cage to a position required by design, cleaning a pile head, setting out a bedding sideline control point by adopting a total station, measuring an elevation by adopting a level gauge, cleaning, compacting and leveling the foundation, installing a template, and performing concrete pouring by adopting an automobile crane batching hopper;
S4: pouring a first layer of concrete on the foundation table 2; firstly, setting out side lines and central lines, measuring the elevation, binding reinforcing steel bars, installing templates, embedding protective sleeves of the pre-stressed anchor cables 3, and pouring concrete;
S5: the anchor pier construction and the tensioning and locking of the prestressed anchor cable 3 are carried out; after the first layer of concrete of the foundation platform 2 reaches the design strength, pouring anchor pier concrete on the concrete surface, lengthening a protective sleeve of the prestressed anchor cable 3 to an anchor backing plate before pouring, tensioning and locking the prestressed anchor cable 3 after the anchor pier concrete reaches the design strength, and then sealing the anchor, wherein the prestressed anchor cable 3 at the outermost layer of the foundation structure is reserved on the second layer of foundation platform 2 for tensioning and sealing the anchor after pouring;
S6: pouring a second layer of concrete on the foundation table 2; binding reinforcing steel bars, installing templates, pre-burying a protective sleeve of the prestressed anchor cable 3, and then pouring concrete;
s7: constructing an anchor pier of the prestressed anchor cable 3 at the uppermost layer and tensioning and sealing the anchor; after the second layer of concrete of the foundation platform 2 reaches the design strength, pouring an anchor pier of the outermost layer of prestressed anchor cable 3 on the concrete surface, lengthening a protective sleeve of the prestressed anchor cable 3 to an anchor backing plate before pouring, tensioning and locking the prestressed anchor cable 3 after the anchor pier concrete reaches the design strength, and then sealing the anchor;
S8: pouring concrete of a third layer of the foundation table 2; binding reinforcing steel bars, installing corrugated pipes on the reinforcing steel bars as drainage pipes, installing templates, hoisting fixed supports and sliding supports, and then performing concrete casting to reserve a pipe ditch.
According to the method, the foundation platform 2 is borne by the pile foundations 1, so that the bearing capacity of the foundation structure meets the requirements, the foundation platform 2 is anchored by the prestress anchor cables 3, the foundation platform 2 is divided into multiple layers for pouring, the reliable anchoring of the prestress anchor cables 3 is realized, the high-energy pulse horizontal impact load generated by the L-shaped water tank is resisted, the stability of the structure is kept, and meanwhile, the integral sedimentation difference and the uneven sedimentation difference of the foundation structure meet the use requirements.
In the embodiment, the diameter of the pile foundation 1 is 1500mm, a steel casing of the pile foundation 1 is rolled by a steel plate with the thickness of 12mm, the inner diameter of the steel casing is 1600mm, the length of the steel casing is 2m, 1-2 grout overflow holes are formed in the upper part of the steel casing, and the steel casing is buried and then is 50cm higher than the ground; the steel pile casing is rolled by a steel plate, so that sufficient strength and rigidity are ensured, and the overflow slurry hole is formed in the top, so that fresh slurry leakage from the bottom opening of the steel pile casing can be avoided during grouting. And (3) after the steel pile casing is pre-buried, backfilling and layering tamping are carried out on the periphery of the bottom and the outer side of the steel pile casing by adopting clay soil.
In this embodiment, in step S1, a slurry tank for preparing and storing fresh slurry is provided, the fresh slurry flows into the pile foundation hole through dead weight during drilling, the slurry mixed with drilling slag is pumped to a sedimentation tank through a slurry pump, the fresh slurry is prepared by adding carboxymethyl vitamins into high-quality bentonite, the weight ratio of bentonite to water in each kilogram of fresh slurry is 28:1, and the indexes of the fresh slurry are: the relative density is 1.04-1.10, the sand content is less than or equal to 1%, the viscosity is 18-30 Pa.s, and the mud indexes in pile foundation holes after hole cleaning are as follows: the relative density is 1.03-1.10, the sand content is less than 2%, the viscosity is 17-20 Pa.s, and the gel content is more than 98%.
Pile foundation holes are constructed by adopting a rotary drilling rig slurry wall protection.
In the embodiment, the pile foundation 1 is poured by concrete with the strength of C30, wherein cement, water, sand, stone=1:0.36:3.42:3.32, slump of 180-200 mm and diffusivity of 340-380 mm, and the construction is performed by adopting a water-proof ball conduit method during pouring.
In the embodiment, in the step S2, the inclination angle between the prestressed anchor cable 3 and the horizontal plane is 30 degrees, the single prestressed anchor cable 3 is formed by adopting 3 phi S15.2 steel strands as a bundle, a grouting pipe is installed, the grouting pipe is reserved according to the design requirement, the free section of the prestressed anchor cable 3 adopts a novel unbonded prestressed reinforcement technology and is positioned at the free section of a soil layer, rust-proof paint is firstly removed, dehydrated butter is coated, a plastic sleeve is sleeved and fastened by lead wires, and adhesive tapes are wound at the boundary between the free section and an anchoring section for fixedly connecting and sealing. The prestress anchor cable 3 is provided with 9 rows of 4 in total, and 36 in total, the structure strength is enough, enough anchoring force can be provided to resist horizontal recoil force when the L-shaped water tank shoots out high-speed water flow, the grouting pipe adopts a P25mm common grouting pipe, the strength meets the use requirement, the distance between the head of the grouting pipe of one-time grouting and the bottom of a hole is preferably 50-100 mm, and the hole is punched 1m above the bottom of the pipe; the grouting pipe for secondary split grouting stretches into the anchoring section for about 2m, the hole is punched 1m above the bottom of the pipe head, the grout outlet hole and the end of the high-pressure grouting pipe are sealed, grout does not enter the secondary high-pressure grouting pipe during primary grouting, grouting pipe reservation is carried out, smooth grouting is guaranteed in the grouting construction process, blocking, pipe bursting or breakage and stretch-breaking are avoided, further, the anti-corrosion and rust-proof treatment of the free section of the prestressed anchor rope 3 is carried out, the service life of the prestressed anchor rope 3 is prolonged, the material, specification and model of the plastic sleeve are required to meet the design requirements, the plastic sleeve has enough strength, the plastic sleeve is not damaged in the processing and mounting processes, shearing and joint cutting are avoided, sealing treatment is carried out if joints are required, pulling-out and breakage phenomena are not generated, the inner diameter of the plastic sleeve is preferably larger than the outer diameter of a strand by 5-10 mm, smooth sleeve penetration is ensured, beam braiding is convenient, and stretching and expansion and crack are prevented. The plastic sleeve has water resistance and chemical stability, and has no adverse reaction when contacted with cement mortar and preservative.
In the embodiment, the anchor hole drilling mode adopts a water drill, a steel pipe is followed during drilling, the anchoring grouting adopts a secondary grouting method, primary normal pressure grouting and secondary splitting grouting, wherein the pressure of the secondary splitting grouting is controlled between 2.5 and 4.0MPa, and the cement slurry ratio is cement: water=1:0.42; when the anchor hole is drilled, a water drill is adopted, the drilling speed and the drilling speed are strictly controlled according to the performance of the drilling machine and the anchored stratum, and the drilling distortion and the diameter change are prevented, so that the anchor is difficult to drop or other accidents are caused. The anchor hole drilling process is followed by a steel pipe with the diameter of 160mm along with the drill bit, so that holes can be formed in a weak stratum, hole collapse is prevented, the drilling cannot be stopped immediately after the drilling reaches the designed depth, and stable drilling is required for 1-2 minutes. The inside of the hole must be cleaned, after the drilling is completed, the rock powder and soil body in the hole are wrapped and clamped by using circulating water to remove the outside of the hole, so as to prevent the adhesive strength between cement paste and the rock-soil body on the hole wall from being reduced, and if necessary, drain holes are arranged at proper positions around the hole.
And the hole inspection is carried out after the anchor hole drilling is finished, the designed hole diameter, the drill bit and the standard drill rod are generally adopted for hole inspection in the hole diameter and hole depth inspection, the drill bit is required to be smoothly pushed in the hole inspection process, no impact or shake is generated, the drill tool inspection and transmission length meets the designed anchor hole depth, the drilling withdrawal requirement is smooth, and rock powder and soil in the hole are cleaned. Drilling inclinometer control and detection, tolerance and requirement of anchor hole drilling: and rechecking the hole position, the inclination angle and the azimuth of each anchor hole, and considering that the anchor holes are qualified after all the anchor holes are qualified. Hole depth: is larger than the design depth by 20cm, and the hole direction is as follows: the inclination angle of the axis is +/-1 degree, axis orientation + -2 DEG, the aperture and the deflection of the hole bottom meet the design requirements.
After the anchor hole is drilled, anchor rib installation should be performed in time, and before the anchor cable is put into a drilled hole, the quality of the rod body should be checked, so that the assembly of the rod body is ensured to meet the design requirement; when the rod body is placed, the rod body is prevented from being twisted and bent, the grouting pipe is preferably placed into the drilling hole along with the anchor cable, the distance between the head of the grouting pipe and the bottom of the drilling hole is preferably 50-100 mm, and the placing angle of the rod body is kept consistent with the drilling hole angle; the depth of the rod body inserted into the hole is not smaller than 98% of the length of the anchor rod, and the rod body cannot be knocked at will after being placed, so that a heavy object cannot be hung.
Before the pre-stressed anchor cable 3 is installed, a safe and convenient working place is needed to be prepared, a manual method is adopted for installing and positioning the pre-stressed anchor cable 3, and before the pre-stressed anchor cable 3 is installed, the anchor cable body and the hole site are checked in detail: and (3) checking the positions and unblocked conditions of the grouting pipes, checking the anchor cable numbers and the drilling hole numbers, and carrying out rope threading installation after the outer skin of the steel dumpling line is damaged before installation and is repaired, wherein the curvature radius of the prestressed anchor cable 3 is not less than 3.0m when the prestressed anchor cable is in rope feeding. In the process of the anchor cable access, the outer skin cannot be damaged, and if the outer skin is damaged, the access can be continued after the repair. The hole of the cable cannot be laid, the hole is re-drilled after the anchor cable is withdrawn and the obstacles in the hole are removed, grouting is performed in time after the prestressed anchor cable 3 is drilled and fixed stably, and the grouting pipe is used for completing continuous grouting of a single anchor cable within 1 hour. And filling the anchoring section of the anchor cable at one time, taking the overflow thick slurry of the orifice slurry as a standard for ending grouting, wherein the actual grouting amount is generally larger than the theoretical grouting amount, and taking out the hole collapse preventing steel pipe when drilling after the primary grouting is finished.
In this embodiment, in step S5, the axial tension value nt=300 kN of the prestressed anchor cable 3 is designed, the prestressed anchor cable 3 is pretensioned 1-2 times according to the 20% axial force standard before the formal tensioning, the anchor cables 3 in the same row are pretensioned in an odd or even staggered manner, the formal tensioning and locking of the prestressed anchor cable 3 are performed in stages, after the tensioning is performed to 1.1-1.2 times of the designed anchoring force, the prestressed anchor cable 3 is maintained for 15min, and then is unloaded to the designed anchoring force and locked, and after the tensioning is completed for 6-10 d, the compensation tensioning is performed again, and then the locking is performed; before formal tensioning, pre-tensioning is carried out for 1-2 times, so that all parts of the pre-stressed anchor cable 3 are tightly contacted, the rod body is completely straight, the tensioning mode avoids damage caused by stress concentration through dislocation tensioning, further, the pre-stressed anchor cable 3 still meets the design axial tension requirement after locking and sealing the anchor through grading tensioning, and the tensioning load grading and observing time of the pre-stressed anchor cable 3 are as follows:
And monitoring the area where the load loss change amplitude of the prestressed anchor cable 3 meets the specified index, namely, the prestress loss is more than 10% of the design tensioning force, carrying out compensation tensioning again after the design tensioning is completed for 6-10 d, and then locking, wherein the relaxation loss is generally 3% -4% of the locking tensioning force (excluding the locking loss). If the prestress value is found to exceed 10% of the design axial force, the prestressing force should be relaxed and then re-tensioned to lower the prestress value.
In order to ensure the safety of the later-stage structure, after tensioning and locking, stress detection is carried out on each pre-stressed anchor cable 3, and whether the stress is lost is checked.
In the embodiment, rust removal is carried out on the anchor head during anchor sealing, the anchor is covered by adopting subsequent upper layer concrete pouring after three times of anti-corrosion paint is coated, and the anchor sealing concrete is not independently poured; the structure is firm and reliable.
In the embodiment, in the steps S4, S6 and S7, a first layer of concrete template of the foundation platform adopts a brick die, a second layer and a third layer adopt a shaping steel template, temperature measuring elements are respectively embedded in the concrete of the three layers of foundation platform 2, each layer of concrete of the foundation platform 2 is cast in batches and tamped in batches, the casting thickness of each batch is 300-400 mm, the casting interval time is longer than 4 hours and is not longer than the initial setting time, and the free falling height of the concrete from the high position is less than 2m; during construction, a first layer of concrete template of the foundation platform 2 is built in a brick moulding bed mode, a second layer of concrete template and a third layer of concrete template are formed by adopting shaping steel plates, wherein the steel templates are brushed with a release agent, the joint is tight and supported firmly, top surface elevation, center line and side line deviation, joint between templates and support are carried out after the installation of the templates, inspection retest is carried out, 9 temperature measuring elements are respectively embedded in 3 layers of concrete of the foundation platform 2 to detect internal temperature change after the concrete is poured, the thickness of the concrete of each layer of foundation platform 2 is controlled in batches, the interval time is kept, heat storage quantity is reduced, the accumulation of hydration heat is avoided, and the temperature stress is reduced.
In the embodiment, concrete is vibrated by adopting an inserted vibrating rod with phi 50mm, the vibrating rod is moved by adopting a determinant, the moving distance is not more than 400mm, the lower batch of concrete is inserted for 50-100 mm when the upper batch of concrete is vibrated, the concrete of each layer of foundation platform 2 is timely subjected to heat preservation and coverage after the die is removed, the two sides of the foundation platform are wrapped by permeable geotextile and closely adhered to the concrete surface, and water is sprayed for keeping moist; the concrete can be uniformly tamped by the vibrating mode, and cold joints are avoided.
In the embodiment, the temperature of the concrete entering the mould is controlled to be 5-30 ℃, the temperature difference between the center and the surface of the concrete is not more than 25 ℃, the temperature difference between the surface temperature and the atmosphere is not more than 20 ℃ when the heat preservation cover is removed from the surface of the concrete casting body, the temperature rise value of the concrete casting body on the basis of the entering temperature is not more than 50 ℃, and the cooling rate of the concrete casting body is not more than 2 ℃/d; the temperature is controlled to avoid the cracking of the concrete structure caused by larger temperature stress due to the overhigh temperature of the concrete in the hydration reaction process.
While the invention has been described in terms of preferred embodiments, it is not intended to be limiting. Many possible variations and modifications of the disclosed technology can be made by anyone skilled in the art, or equivalent embodiments with equivalent variations can be made, without departing from the scope of the invention. Therefore, any simple modification, equivalent variation and modification of the above embodiments according to the technical substance of the present invention shall fall within the scope of the technical solution of the present invention.
Claims (10)
1. A pile-anchor combined foundation structure construction method is characterized in that: the foundation structure comprises a plurality of pile foundations (1), a foundation table (2) for bearing an L-shaped water tank is poured on the pile foundations (1), a plurality of prestressed anchor cables (3) for tensioning and anchoring the foundation structure are arranged on the foundation table (2), a fixed support and a sliding support for fixing the L-shaped water tank are further arranged on the foundation table (2), and the foundation table (2) is poured in three layers; the construction method comprises the following steps:
S1: pouring pile foundations (1); leveling the site before construction, accurately positioning the center of the pile foundation (1) according to the coordinates of the pile foundation by using a total station, arranging a cross pile protection outside a range of 1.5m, burying a steel pile protection cylinder in the center of the pile foundation (1), drilling by using a drilling machine, cleaning holes after hole forming, changing slurry, installing a reinforcement cage after the pile foundation holes are inspected to be qualified, arranging a guide pipe, and directly pouring and forming by using a concrete tank truck;
S2: the prestressed anchor cable (3) is arranged and constructed; digging a foundation pit by using an excavator, making a drainage ditch, leveling the ground, laying out points by points according to the design coordinates of hole sites, marking, drilling by using a drilling machine, cleaning after forming an anchor hole, immediately installing a pre-stressed anchor cable (3) into the hole after the anchor hole is inspected to be qualified, and grouting in time after stabilizing;
S3: pouring a cushion layer; firstly, setting out a foundation sideline, digging a foundation pit by adopting manual cooperation with machinery, then, performing concrete breaking on an overcast part of a pile foundation (1), adjusting a reinforcement cage to a design requirement position, cleaning a pile head, setting out a bedding sideline control point by adopting a total station, measuring an elevation by adopting a level gauge, cleaning, compacting and leveling the foundation, installing a template, and performing concrete pouring by adopting an automobile crane proportioning hopper;
S4: pouring a first layer of concrete on the foundation table (2); firstly, setting out side lines and central lines, measuring the elevation, binding reinforcing steel bars, installing templates, embedding protective sleeves of pre-stressed anchor cables (3), and pouring concrete;
S5: the anchor pier construction and the tensioning and locking of the prestressed anchor cable (3); after the first layer of concrete of the foundation platform (2) reaches the design strength, pouring anchor pier concrete on the concrete surface, lengthening a protective sleeve of the prestressed anchor cable (3) to an anchor backing plate before pouring, tensioning and locking the prestressed anchor cable (3) after the anchor pier concrete reaches the design strength, and then sealing the anchor, wherein the prestressed anchor cable (3) at the outermost layer of the foundation structure is reserved on the second layer of the foundation platform (2) for tensioning and sealing the anchor after pouring;
S6: pouring a second layer of concrete on the foundation table (2); binding reinforcing steel bars, installing templates, pre-burying a protective sleeve of the prestressed anchor cable (3), and then pouring concrete;
S7: the uppermost layer of prestressed anchor cable (3) is constructed by anchor piers and tensioned to seal anchors; after the second layer of concrete of the foundation platform (2) reaches the design strength, pouring an anchor pier of the outermost layer of prestressed anchor cable (3) on the concrete surface, lengthening a protective sleeve of the prestressed anchor cable (3) to an anchor backing plate before pouring, tensioning and locking the prestressed anchor cable (3) after the anchor pier concrete reaches the design strength, and then sealing the anchor;
S8: pouring concrete of a third layer of the foundation table (2); binding reinforcing steel bars, installing corrugated pipes on the reinforcing steel bars as drainage pipes, installing templates, hoisting fixed supports and sliding supports, and then performing concrete casting to reserve a pipe ditch.
2. A pile-anchor combined foundation structure construction method according to claim 1, wherein: in step S1, a slurry tank for preparing and storing fresh slurry is provided, the fresh slurry flows into the pile foundation hole by self weight during drilling, and the slurry mixed with drilling slag is pumped to a sedimentation tank by a slurry pump.
3. A pile-anchor combined foundation structure construction method according to claim 2, wherein: the pile foundation (1) is cast by adopting concrete with the strength of C30, and is constructed by adopting a waterproof ball conduit method during casting.
4. A pile-anchor combined foundation structure construction method according to claim 1, wherein: in the step S2, the inclination angle between the prestressed anchor cable (3) and the horizontal plane is 30 degrees, the single prestressed anchor cable (3) is formed by adopting 3 phi S15.2 steel strands as a bundle, a grouting pipe is arranged, the free section of the prestressed anchor cable (3) is firstly subjected to rust removal and rust prevention paint, then is coated with dehydrated butter, then is sheathed with a plastic sleeve and is tightly bound by lead wires, and the boundary part of the free section and the anchoring section is wound with adhesive tape for fixedly connecting and sealing.
5. The pile-anchor composite foundation structure construction method of claim 4, wherein: the anchor hole drilling mode adopts a water drill, a steel pipe is followed during drilling, the anchoring grouting adopts a secondary grouting method, primary normal pressure grouting and secondary splitting grouting, wherein the pressure of the secondary splitting grouting is controlled between 2.5 MPa and 4.0MPa, and the cement slurry ratio is cement: water=1:0.42.
6. A pile-anchor combined foundation structure construction method according to claim 1, wherein: in the step S5, the designed axial tension value N t = 300kN of the prestressed anchor cable (3), the prestressed anchor cable (3) is stretched for 1-2 times according to the 20% axial force standard before the formal stretching, the prestressed anchor cable (3) of the same line is stretched in a staggered manner according to an odd number or an even number, the formal stretching and locking classification of the prestressed anchor cable (3) are carried out, the anchor cable is maintained for 15min after the stretching of the anchor cable is stretched to 1.1-1.2 times of the designed anchoring force, then the anchor cable is unloaded to the designed anchoring force and locked, and after the stretching is completed for 6-10 d, the compensation stretching is carried out again, and then the anchor cable is locked.
7. The pile-anchor composite foundation structure construction method of claim 6, wherein: and rust removal is carried out on the anchor head during anchor sealing, the anchor is covered by adopting subsequent upper layer concrete pouring after three times of anti-corrosion paint are coated, and the anchor sealing concrete is not independently poured.
8. A pile-anchor combined foundation structure construction method according to claim 1, wherein: in the steps S4, S6 and S7, the first layer of concrete template of the foundation platform (2) adopts a brick die, the second layer and the third layer adopt a shaping steel template, temperature measuring elements are pre-embedded in the concrete of the three layers of foundation platform (2), the concrete of each layer of foundation platform (2) adopts batch casting batch tamping, the casting thickness of each batch is 300-400 mm, the casting interval time is longer than 4h and not longer than the initial setting time, and the free falling height of the concrete from the high position is less than 2m.
9. The pile-anchor composite foundation structure construction method of claim 8, wherein: the concrete is vibrated by adopting a phi 50mm inserted vibrating rod, the vibrating rod moves by adopting a determinant, the moving distance is not more than 400mm, the lower batch of concrete is inserted for 50-100 mm when the upper batch of concrete is vibrated, the heat preservation and the coverage are timely carried out after the concrete of each layer of foundation platform (2) is removed, the two sides are wrapped by permeable geotextile closely attached to the concrete surface, and the sprinkling water is kept moist.
10. A pile-anchor composite foundation construction method according to claim 9, wherein: the temperature of the concrete in the mold is controlled to be 5-30 ℃, the temperature difference between the center and the surface of the concrete is not more than 25 ℃, the temperature difference between the surface temperature and the atmosphere is not more than 20 ℃ when the heat preservation cover is removed from the surface of the concrete casting body, the temperature rise value of the concrete casting body on the basis of the temperature of the concrete in the mold is not more than 50 ℃, and the cooling rate of the concrete casting body is not more than 2 ℃/d.
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| CN106759442A (en) * | 2017-01-05 | 2017-05-31 | 中建三局第二建设工程有限责任公司 | A kind of single-pile elevated bearing-platform and anchor cable tower-crane foundation structure and its construction method |
| CN108867376A (en) * | 2018-06-14 | 2018-11-23 | 张学武 | Face anchor system and its construction method after mating type forever |
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| JPH09316892A (en) * | 1996-05-30 | 1997-12-09 | Aruku Plan:Kk | Pile foundation reinforcing structure |
| CN204266121U (en) * | 2014-11-12 | 2015-04-15 | 中铁十八局集团有限公司 | Button anchor system combinations formula pile foundation support table anchorage |
| CN215329988U (en) * | 2021-07-27 | 2021-12-28 | 中铁西北科学研究院有限公司 | Prestressed anchor cable pile tied in a bundle |
| CN114086554A (en) * | 2021-11-30 | 2022-02-25 | 广西路桥工程集团有限公司 | Permanent temporary combined type ground anchor and establishing method thereof |
| CN115419104A (en) * | 2022-09-25 | 2022-12-02 | 贵州路桥集团有限公司 | Cable crane combined type anchorage structure and using method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106759442A (en) * | 2017-01-05 | 2017-05-31 | 中建三局第二建设工程有限责任公司 | A kind of single-pile elevated bearing-platform and anchor cable tower-crane foundation structure and its construction method |
| CN108867376A (en) * | 2018-06-14 | 2018-11-23 | 张学武 | Face anchor system and its construction method after mating type forever |
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