CN108643215B - Construction method of anchor pier type foundation after rotary spraying and pressing into variable cross section - Google Patents
Construction method of anchor pier type foundation after rotary spraying and pressing into variable cross section Download PDFInfo
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- CN108643215B CN108643215B CN201810438124.6A CN201810438124A CN108643215B CN 108643215 B CN108643215 B CN 108643215B CN 201810438124 A CN201810438124 A CN 201810438124A CN 108643215 B CN108643215 B CN 108643215B
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D27/00—Foundations as substructures
- E02D27/10—Deep foundations
- E02D27/12—Pile foundations
- E02D27/14—Pile framings, i.e. piles assembled to form the substructure
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D15/00—Handling building or like materials for hydraulic engineering or foundations
- E02D15/02—Handling of bulk concrete specially for foundation or hydraulic engineering purposes
- E02D15/04—Placing concrete in mould-pipes, pile tubes, bore-holes or narrow shafts
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/48—Piles varying in construction along their length, i.e. along the body between head and shoe, e.g. made of different materials along their length
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Abstract
The invention relates to a construction method of a anchor pier type foundation after rotary spraying and pressing in a variable cross section, which is characterized in that a variable cross section prefabricated pier is prepared in a prefabrication factory, a stiffening core steel pipe and a rotary spraying anchoring hole are arranged in the prefabricated pier, pier side connecting ribs and pier side grouting pipes are arranged on the outer side of the prefabricated pier, and a pier top anchor base plate is arranged on the top of the prefabricated pier; when the prefabricated pier sinks, water is pressed through the pressure water pipe to wash the soil body at the bottom of the prefabricated pier, and vertical downward pressure is applied to the prefabricated pier; after the prefabricated pier sinks to a set depth, firstly, arranging anchoring steel bars between the prefabricated pier and a lower soil body, then arranging a pier bottom connector at the bottom of the prefabricated pier, and then performing prefabricated pier prepressing and anchoring steel bar tensioning construction; arranging pier side grouting bodies outside the prefabricated piers, and arranging steel pipe filling bodies in the stiffening core steel pipes; and finally, carrying out pier top bearing platform construction. The invention can not only improve the field construction efficiency and the vertical bearing capacity of the prefabricated pier, but also improve the uplift resistance of the prefabricated pier and reduce the influence of the sediment on the bearing capacity of the prefabricated pier.
Description
Technical Field
The invention relates to a construction method of a prefabricated pier type foundation, in particular to a construction method of an anchor pier type foundation after rotary spraying and pressing into a variable cross section, which belongs to the technical field of foundation treatment and is particularly suitable for foundation treatment engineering of sandy soil, cohesive soil and powder soil foundation.
Background
In civil engineering, basic construction is often required to effectively bear the load of the superstructure. At present, the pier foundation is most widely applied, in particular to projects such as bridges, landslide treatment, high-rise buildings, port wharfs and the like. The pier foundation is a short, thick and deep foundation formed by drilling or punching a hole in a foundation and pouring concrete, and the depth of the foundation is usually 3 to 6 m. The common structures of the pier foundation are a straight bottom pier and a rock-socketed pier, the pier body is made of concrete materials, and corresponding reinforcing bars are arranged according to the bearing requirements. In order to further improve the bearing capacity of the pier foundation, the pier bottom can be designed into an expanded bottom shape, and a horizontal reinforcing mesh is arranged at the pier bottom. Although the design can meet the bearing requirement of the engineering structure in the vertical direction, the friction resistance of the pile side of the structure is low, and the horizontal load resistance and the pulling resistance of the pile side of the structure are poor.
The utility model discloses a pier foundation structure in chinese utility model patent CN201120455693.5, it includes pier foundation component, and this pier foundation component's transversal is circular or oval, and its upper portion's periphery sets up the steel sheet dado, and its lower part is the downward cone form that enlarges gradually, and the bottom is bottom of a boiler shape or flat shape, and the embedded joint dowel in pier top. The structure is a prototype structure of the pier foundation, and although the structure can have the characteristics of an independent foundation and a pile foundation to a certain extent, the construction is mainly cast in place, the construction efficiency is low, and the problems of poor uplift resistance, low bearing capacity and the like of the pier foundation are difficult to solve.
The invention discloses a fan pile foundation and a construction method thereof in Chinese patent CN201510022371.4, the fan pile foundation comprises a center pile foundation, an anchor rod pile is arranged at the bottom of the center pile foundation, a plurality of inclined piles are arranged around the anchor rod pile, a concrete bearing platform is arranged at the top of the center pile foundation, a prestressed anchor rod is arranged in the concrete bearing platform, a steel bar at the top of the inclined pile is connected with a steel bar of the concrete bearing platform, and the concrete bearing platform and the inclined piles are poured into a whole. Although the structure can enhance the bearing capacity of the foundation to a certain extent and can play a role of combining the piles, the pier body is cast-in-place concrete, and the quality of site construction is difficult to control.
In view of the actual needs of the current foundation engineering, the pier foundation and the construction method thereof are needed to improve the field construction efficiency, improve the vertical bearing capacity of the prefabricated pier, improve the uplift resistance of the prefabricated pier and reduce the influence of the sediment on the bearing capacity of the prefabricated pier.
Disclosure of Invention
The invention aims to provide a construction method of a jet grouting press-in variable-section rear anchor pier type foundation, which can effectively improve the field construction efficiency and the bearing capacity of a prefabricated pier and improve the field construction quality.
In order to realize the purpose, the invention adopts the following technical scheme:
a construction method of a jet grouting and variable cross-section rear anchor pier type foundation comprises the following construction steps:
1) construction preparation: performing field engineering investigation, determining the height of the prefabricated pier and the soil property of the soil body around the prefabricated pier, and preparing materials such as a stiffened core steel pipe, an anchoring steel bar, a rear grouting pipe and the like required by construction;
2) preparing a prefabricated pier: preparing a prefabricated pier with a variable cross section and a stiffening core steel pipe at the central part in a prefabrication plant; a plurality of rotary spraying anchoring holes penetrating through the top and the bottom of the prefabricated pier are uniformly distributed in the prefabricated pier in the circumferential direction, pier side connecting ribs and pier side grouting pipes are arranged on the outer side of the prefabricated pier, and a pier top anchoring base plate is arranged on the top of the prefabricated pier; an oblique connecting rib is also arranged between the pier top anchor backing plate and the stiffening core steel pipe;
3) sinking the prefabricated pier: sleeving 2-3 water stop rings on a pressure water pipe, inserting the pressure water pipe into a rotary spraying anchoring hole, pressing water on the pressure water pipe through high-pressure water injection equipment to flush out a peripheral soil body of the prefabricated pier, and simultaneously carrying out downward static pressure on the prefabricated pier through static pressure equipment until the prefabricated pier is sunk to the designed depth;
4) and (3) anchoring steel bars: after the prefabricated pier is sunk to the designed depth, the pressure water pipe is taken out, then a plurality of pier bottom anchoring holes are correspondingly drilled in the soil body at the bottom of the prefabricated pier downwards along the rotary spraying anchoring holes by adopting drilling equipment, then the pier bottom anchoring holes are cleaned, anchoring reinforcing steel bars are inserted into the rotary spraying anchoring holes and the pier bottom anchoring holes, and finally, grouting is carried out in the pier bottom anchoring holes to form anchoring sections of the anchoring reinforcing steel bars;
5) constructing a pier bottom connector: inserting the rear grouting pipe into the stiffening core steel pipe, and then grouting the bottom of the prefabricated pier through the rear grouting pipe to form a pier bottom connector;
6) pre-pressing the prefabricated pier: before the pier bottom connector is finally set, the prefabricated pier is pressed downwards through static pressure equipment so that the bottom of the prefabricated pier is tightly connected with the pier bottom connector, and meanwhile, the spatial position of the prefabricated pier needs to be checked;
7) stretching the anchoring steel bar: after the grout of the anchoring section of the anchoring steel bar is solidified to the designed strength, synchronously stretching the free section of the anchoring steel bar, and then firmly connecting the anchoring steel bar with the pier top anchoring base plate through the anchoring ring and the clamping piece;
8) pier side grouting construction: after the anchoring steel bars are tensioned, grouting is carried out through the pressure in the pier side grouting pipe so as to form pier side grouting body on the outer side of the prefabricated pier;
9) and (3) pier top bearing platform construction: and (3) firstly, firmly connecting the anchoring steel bars, the steel pipe with the pier top bearing platform, grouting into the steel pipe with the steel core to form a steel pipe filling body, and finally pouring on the top of the prefabricated pier to form the pier top bearing platform.
Furthermore, the prefabricated pier in the step 2) is a circular truncated cone or a truncated pyramid, is made of plain concrete or reinforced concrete and has a height of 2-6 m;
furthermore, the cross section of the steel pipe with the stiff core in the step 2) is circular or oval, the bottom of the steel pipe with the stiff core protruding out of the prefabricated pier is 4-10 cm, the top of the steel pipe with the stiff core protruding out of the prefabricated pier is 10-20 cm, and slurry seepage holes are formed in the two ends of the steel pipe with the stiff core;
furthermore, the pier side connecting rib in the step 2) is a twisted steel bar or a steel pipe or a steel sheet.
Further, the pier top anchor backing plate in the step 2) is a rolled steel plate, the plane size of the rolled steel plate is the same as that of the top surface of the prefabricated pier, and a steel core steel pipe penetrating hole and an anchoring steel bar penetrating hole are further formed in the pier top anchor backing plate.
Furthermore, the pressure water pipe in the step 3) is a steel pipe, and the water stop ring is a rubber ring.
Furthermore, the top surface of the prefabricated pier is kept horizontal when the prefabricated pier is pre-pressed in the step 6), and the pre-pressing load is 0.1-0.3 times of the design value of the bearing capacity of the prefabricated pier.
Furthermore, the anchoring steel bar in the step 7) is a twisted steel bar, and the top of the anchoring steel bar protrudes out of the anchor ring by 5-10 cm after tensioning is completed.
Further, the anchoring steel bars and the pier top bearing platform steel bars in the step 9) are welded or bound, the stiffening core steel pipes and the pier top bearing platform steel bars are welded, and the steel pipe filling bodies are made of bubble concrete or concrete with strength not lower than the strength of the prefabricated piers.
Compared with the prior art, the invention has the following characteristics and beneficial effects:
1. when the prefabricated pier is constructed in a sinking way, the peripheral soil body of the prefabricated pier is flushed through the pressure water pipe, so that the peripheral soil body can discharge slurry through the stiffening core steel pipe and the side surface of the prefabricated pier, the difficulty of the prefabricated pier in the sinking construction is greatly reduced, and the hole forming cost of the prefabricated pier in the sinking construction is saved;
2. the prefabricated pier in the invention adopts the variable cross-section design and can be prepared in a prefabrication factory, thus not only saving the preparation cost of the prefabricated pier, improving the quality of the prefabricated pier, but also shortening the construction period on site;
3. according to the invention, the pier bottom connector is arranged at the bottom of the prefabricated pier, the pier side grouting body is arranged at the outer side of the prefabricated pier, and the stiffening core steel pipe and the steel pipe filler are arranged in the middle of the pier, so that the bearing capacity of the prefabricated pier and the peripheral soil body can be effectively improved, and the stress property of the prefabricated pier is improved;
4. according to the invention, the anchoring steel bars are arranged between the prefabricated pier and the bottom soil body of the prefabricated pier, and certain prestress is applied to the anchoring steel bars, so that the horizontal bearing capacity and the uplift resistance of the prefabricated pier can be effectively improved;
5. according to the invention, after the anchoring steel bars and the stiffening core steel pipes are connected with the pier top bearing platform steel bars, the concrete pouring of the pier top bearing platform is carried out, so that the connection strength of the prefabricated pier and the upper structure can be greatly improved.
Drawings
FIG. 1 is a schematic structural diagram of an anchor pier type foundation after rotary spraying and pressing into a variable cross section.
Fig. 2 is a schematic structural view after the prefabricated pier is sunk and completed.
Fig. 3 is a schematic structural view after the construction of the pier bottom connector is completed.
Figure 4 is a cross-sectional view of the pier top anchor pad.
FIG. 5 is a flow chart of the construction method of the anchor pier type foundation after the jet grouting is pressed into the variable cross section.
Illustration of the drawings: 1-prefabricated pier, 2-stiffened steel pipe, 3-anchoring steel bar, 4-rear grouting pipe, 5-jet grouting anchoring hole, 6-pier side connecting bar, 7-pier side grouting pipe, 8-pier top anchoring base plate, 9-oblique connecting bar, 10-pressure water pipe, 11-water stop ring, 12-peripheral soil body, 13-bottom soil body, 14-pier bottom anchoring hole, 15-anchoring section, 16-pier bottom connecting body, 17-free section, 18-anchoring ring, 19-clamping piece, 20-pier side grouting body, 21-pier top bearing platform steel bar, 22-steel pipe filling body, 23-pier top bearing platform, 24-grout seepage hole, 25-stiffened steel pipe penetrating hole and 26-anchoring steel bar penetrating hole.
Detailed Description
The invention will be further described with reference to the drawings and preferred embodiments.
The design and construction technical requirements of the precast pier, the concrete pouring construction requirements, the hoisting construction technical requirements of the stiffened core steel pipe, the field construction technical requirements of the anchoring steel bar and the like are not described in detail in the embodiment.
Fig. 1 is a schematic structural diagram of an anchor pier type foundation after rotary jetting and pressing into a variable cross section, which comprises a prefabricated pier 1, anchor steel bars 3, a pier bottom connector 16, an anchor ring 18, a clamping piece 19, pier side grouting 20, pier top bearing platform steel bars 21, a steel pipe filling body 22 and a pier top bearing platform 23.
The prefabricated pier 1 is a circular truncated cone-shaped pier foundation prepared in a prefabrication factory, the height of the prefabricated pier 1 is 3m, the diameter of the top surface is 1.2m, and the diameter of the bottom surface is 1.4 m; the prefabricated pier 1 is made of plain concrete and has the strength grade of C30; a stiffening core steel pipe 2 is arranged at the central part of the prefabricated pier 1, the diameter of the stiffening core steel pipe 2 is 300mm, the wall thickness is 2mm, the strength grade is Q235, the bottom surface of the prefabricated pier protruding from the bottom 1 is 10cm, the top surface of the prefabricated pier protruding from the top 1 is 20cm, slurry seepage holes 24 with the aperture of 30mm are also arranged at the two ends of the stiffening core steel pipe 2; 6 rotary spraying anchoring holes 5 penetrating through the top and the bottom of the prefabricated pier 1 are uniformly distributed in the prefabricated pier 1 in the circumferential direction, the diameter of each rotary spraying anchoring hole 5 is 110mm, and the distance between each rotary spraying anchoring hole 5 and the center of the steel pipe 2 with the stiffening core is 300 mm; a plurality of pier side connecting ribs 6 are uniformly and fixedly connected to the side wall of the prefabricated pier 1 along the horizontal direction, the pier side connecting ribs 6 adopt twisted steel bars with the diameter of 32mm, and the length of the pier side connecting ribs is 100 mm; 6 pier side grouting pipes 7 are vertically and uniformly fixedly connected with the outer wall of the prefabricated pier 1, the pier side grouting pipes 7 are steel pipes with the diameter of 60mm, and the wall thickness is 1 mm; the top of the prefabricated pier 1 is also fixedly connected with a pier top anchor backing plate 8, the pier top anchor backing plate 8 is a round rolled steel plate with the thickness of 1cm and the diameter of 1.2m, and the strength grade is Q235; a steel core steel pipe through hole 25 and an anchoring steel bar through hole 26 are arranged on the pier top anchor base plate 8, and the hole diameters of the steel core steel pipe through hole and the anchoring steel bar through hole are 330mm and 60mm respectively; 6 oblique connecting ribs 9 are also circumferentially and uniformly welded between the pier top anchor backing plate 8 and the stiffening core steel pipe 2, and the oblique connecting ribs 9 adopt twisted steel bars with the diameter of 32 mm.
6 pier bottom anchoring holes 14 are drilled in the bottom soil body 13 of the prefabricated pier 1, the pier bottom anchoring holes 14 correspond to the rotary spraying anchoring holes 5 one by one, and the diameter of each pier bottom anchoring hole 14 is 110mm, and the depth of each pier bottom anchoring hole is 2 m. All inserted anchoring reinforcing bar 3 in above-mentioned whirl jet anchor hole 5 and pier bottom anchor hole 14, this anchoring reinforcing bar 3 adopts the twisted steel that the diameter is 25 mm. A certain amount of grout is injected into the pier bottom anchoring hole 14 to anchor the bottom of the anchoring steel bar 3, that is, an anchoring section 15 is formed at the bottom of the anchoring steel bar 3, the length of the anchoring section 15 is also 2m, the upper part of the anchoring steel bar 3 is a free section 17, and the length of the free section is 3 m. At the top of the free section 17 are mounted an anchor ring 18 and a clip 19 which rest on the pier top anchor plate 8 to anchor the top of the anchoring bar 3.
The bottom of the prefabricated pier 1 is fixedly connected with a pier bottom connector 16, the pier bottom connector 16 is made of cement mortar, and the thickness of the pier bottom connector is 0.2 m. The side surface of the prefabricated pier 1 is fixedly connected with pier side grouting body 20, the pier side grouting body 20 is made of fine aggregate concrete, and the strength grade is C30.
And a pier top bearing platform 23 is further poured on the top of the prefabricated pier 1, the height of the pier top bearing platform 23 is 300mm, the material is concrete, and the strength grade is C35. Pier top bearing platform reinforcing steel bars 21 are laid in the pier top bearing platform 23, and the pier top bearing platform reinforcing steel bars 21 are threaded reinforcing steel bars with the diameter of 25 mm. The pier top bearing platform steel bars 21 are bound together with the top ends of the anchoring steel bars 3 and are welded with the steel pipe 2 with the stiffness core. Further, a steel pipe filler 22 is provided in the core steel pipe 2, and the steel pipe filler 22 is made of fine aggregate concrete and has a strength grade of C35.
FIG. 5 shows a flow chart of the construction method of the anchor pier type foundation after the jet grouting and the press-in of the variable cross-section, which comprises the following construction steps:
1) construction preparation: performing field engineering investigation, determining the height of the prefabricated pier 1 and the soil properties of the soil body 12 around the prefabricated pier 1 and the soil body 13 at the bottom, and preparing materials such as a stiffened core steel pipe 2, anchoring steel bars 3, a rear grouting pipe 4 and the like required by construction; in the embodiment, the peripheral soil body 12 of the prefabricated pier 1 and the bottom soil body 13 of the prefabricated pier 1 are medium coarse sand in a medium dense state and medium coarse sand in a dense state respectively;
2) preparing a prefabricated pier 1: preparing a prefabricated pier 1 with a variable cross section and a stiffening core steel pipe 2 at the central part in a prefabrication plant;
3) sinking the prefabricated pier 1: sleeving 3 water stop rings 11 on a pressure water pipe 10, inserting the pressure water pipe 10 into a jet grouting anchoring hole 5, pressing the pressure water pipe 10 by using high-pressure water injection equipment to flush out a peripheral soil body 12 of the prefabricated pier 1, and simultaneously carrying out downward static pressure on the prefabricated pier 1 by using static pressure equipment until the prefabricated pier 1 is sunk to the designed depth; the pressure water pipe 10 adopts a steel pipe with the diameter of 30mm, the water stop ring 11 adopts a rubber ring, and the water stop ring 11 can be well sealed; fig. 2 is a schematic structural diagram of the prefabricated pier after sinking.
4) And (3) construction of an anchoring steel bar: after the prefabricated pier 1 is sunk to the designed depth, the pressure water pipe 10 is taken out, then a plurality of pier bottom anchoring holes 14 are correspondingly drilled in a bottom soil body 13 of the prefabricated pier 1 downwards along the rotary spraying anchoring hole 5 by adopting drilling equipment, then the pier bottom anchoring holes 14 are cleaned up, anchoring steel bars 3 are inserted into the rotary spraying anchoring holes 5 and the pier bottom anchoring holes 14, and finally grouting is performed in the pier bottom anchoring holes 14 to form anchoring sections 15 of the anchoring steel bars 3;
5) constructing a pier bottom connector 16: inserting the rear grouting pipe 4 into the steel pipe 2, and then grouting the bottom of the prefabricated pier 1 through the rear grouting pipe 4 to form a pier bottom connector 16; the rear grouting pipe 4 is a steel pipe with the diameter of 60 mm; FIG. 3 is a schematic structural view of the pier bottom connector after construction is completed;
6) pre-pressing a prefabricated pier 1: before the pier bottom connecting body 16 is finally set, the prefabricated pier 1 is subjected to downward static pressure through static pressure equipment so that the bottom of the prefabricated pier 1 is tightly connected with the pier bottom connecting body 16, and meanwhile, the spatial position of the prefabricated pier 1 needs to be checked; the top surface of the prefabricated pier 1 is kept horizontal when the prefabricated pier 1 is pre-pressed, and the pre-pressing load is 0.1-0.3 time of the design value of the bearing capacity of the prefabricated pier 1;
7) tensioning an anchoring steel bar 3: after the grout of the anchoring section 15 of the anchoring steel bar 3 is solidified to the designed strength, synchronously stretching the free section 17 of the anchoring steel bar 3, and then firmly connecting the anchoring steel bar 3 with the pier top anchoring base plate 8 through the anchor ring 18 and the clamping piece 19; the top of the free section 17 of the anchoring steel bar 3 protrudes out of the anchor ring 18 by 10cm after tensioning is finished;
8) construction of pier side grouting body 20: after the anchoring steel bars 3 are tensioned, grouting is carried out on the inner side of the pier side grouting pipe 7 through pressure to form pier side grouting body 20 on the outer side of the prefabricated pier 1;
9) constructing the pier top bearing platform 23: the anchoring steel bars 3 and the steel core steel pipes 2 are firmly connected with the pier top bearing platform steel bars 21, then steel pipe filling bodies 22 are formed by grouting in the steel core steel pipes 2, and finally the pier top bearing platform 23 is formed by pouring on the top of the prefabricated pier 1.
The foregoing merely represents preferred embodiments of the invention, which are described in some detail and detail, and therefore should not be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, various changes, modifications and substitutions can be made without departing from the spirit of the present invention, and these are all within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (7)
1. A construction method of a jet grouting and variable cross-section rear anchor pier type foundation is characterized by comprising the following construction steps:
1) construction preparation: performing field engineering investigation, and determining the height of the prefabricated pier (1) and the soil property of the soil body (12) around the prefabricated pier (1);
2) preparing a prefabricated pier (1): preparing a prefabricated pier (1) with a variable cross section and a stiffening core steel pipe (2) at the central part in a prefabrication plant; the prefabricated pier (1) is a circular truncated cone or a prismatic table, is made of plain concrete or reinforced concrete and has the height of 2-6 m; a plurality of rotary spraying anchoring holes (5) penetrating through the top and the bottom of the prefabricated pier (1) are uniformly distributed in the prefabricated pier (1) in the circumferential direction, pier side connecting ribs (6) and pier side grouting pipes (7) are arranged on the outer side of the prefabricated pier (1), and a pier top anchoring base plate (8) is arranged on the top of the prefabricated pier (1); an oblique connecting rib (9) is arranged between the pier top anchor backing plate (8) and the stiffening core steel pipe (2); the cross section of the steel tube (2) is circular or oval, the bottom surface of the steel tube, which protrudes out of the prefabricated pier (1), is 4-10 cm, the top surface of the steel tube, which protrudes out of the prefabricated pier (1), is 10-20 cm, and slurry seepage holes (24) are formed in the two ends of the steel tube (2);
3) sinking the prefabricated pier (1): sleeving 2-3 water stop rings (11) on a pressure water pipe (10), inserting the pressure water pipe (10) into a jet grouting anchoring hole (5), pressing the pressure water pipe (10) through high-pressure water injection equipment to flush out a peripheral soil body (12) of the prefabricated pier (1), and simultaneously carrying out downward static pressure on the prefabricated pier (1) through static pressure equipment until the prefabricated pier (1) is sunk to the designed depth;
4) and (3) construction of the anchoring steel bar: after the prefabricated pier (1) is sunk to the designed depth, the pressure water pipe (10) is taken out, then a plurality of pier bottom anchoring holes (14) are correspondingly drilled in a bottom soil body (13) of the prefabricated pier (1) downwards along the rotary spraying anchoring holes (5) by adopting drilling equipment, then the pier bottom anchoring holes (14) are cleaned, anchoring steel bars (3) are inserted into the rotary spraying anchoring holes (5) and the pier bottom anchoring holes (14), and finally grouting is injected into the pier bottom anchoring holes (14) to form anchoring sections (15) of the anchoring steel bars (3);
5) constructing a pier bottom connector (16): inserting the rear grouting pipe (4) into the steel pipe (2), and then grouting the bottom of the prefabricated pier (1) through the rear grouting pipe (4) to form a pier bottom connector (16);
6) pre-pressing the prefabricated pier (1): before the pier bottom connector (16) is finally set, the prefabricated pier (1) is subjected to downward static pressure through static pressure equipment so that the bottom of the prefabricated pier (1) is tightly connected with the pier bottom connector (16), and meanwhile, the spatial position of the prefabricated pier (1) needs to be checked; the pre-compression load is 0.1-0.3 times of the design value of the bearing capacity of the prefabricated pier (1);
7) tensioning the anchoring steel bar (3): after the grout of the anchoring section (15) of the anchoring steel bar (3) is solidified to the designed strength, synchronously stretching the free section (17) of the anchoring steel bar (3), and then firmly connecting the anchoring steel bar (3) with the pier top anchoring base plate (8) through an anchor ring (18) and a clamping piece (19);
8) constructing pier side grouting body (20): after the anchoring steel bars (3) are tensioned, grouting is carried out through the pressure in the pier side grouting pipes (7) so as to form pier side grouting bodies (20) on the outer sides of the prefabricated piers (1);
9) constructing a pier top bearing platform (23): firstly, the anchoring steel bars (3) and the steel pipe (2) with the pier top bearing platform steel bars (21) are firmly connected, then grouting is performed in the steel pipe (2) with the steel pipe to form a steel pipe filling body (22), and finally the pier top bearing platform (23) is formed by pouring on the top of the prefabricated pier (1).
2. The construction method of the anchor pier type foundation after the jet grouting is pressed into the variable cross section according to the claim 1, which is characterized in that: the pier side connecting rib (6) in the step 2) is a twisted steel bar or a steel pipe or a steel sheet.
3. The construction method of the anchor pier type foundation after the jet grouting is pressed into the variable cross section according to the claim 1, which is characterized in that: the pier top anchor backing plate (8) in the step 2) is a rolled steel plate, the plane size of the rolled steel plate is the same as that of the top surface of the prefabricated pier (1), and a steel core steel pipe penetrating hole (25) and an anchoring steel bar penetrating hole (26) are further formed in the pier top anchor backing plate (8).
4. The construction method of the anchor pier type foundation after the jet grouting is pressed into the variable cross section according to the claim 1, which is characterized in that: the pressure water pipe (10) in the step 3) is a steel pipe, and the water stop ring (11) is a rubber ring.
5. The construction method of the anchor pier type foundation after the jet grouting is pressed into the variable cross section according to the claim 1, which is characterized in that: and in the step 6), the top surface of the prefabricated pier (1) is kept horizontal when the prefabricated pier (1) is pre-pressed.
6. The construction method of the anchor pier type foundation after the jet grouting is pressed into the variable cross section according to the claim 1, which is characterized in that: the anchoring steel bar (3) in the step 7) is a thread steel bar, and the top of the anchoring steel bar protrudes out of the anchor ring (18) by 5-10 cm after tensioning is completed.
7. The construction method of the anchor pier type foundation after the jet grouting is pressed into the variable cross section according to the claim 1, which is characterized in that: the anchoring steel bars (3) in the step 9) are connected with the pier top bearing platform steel bars (21) in a welding or binding mode, the stiff core steel pipes (2) are connected with the pier top bearing platform steel bars (21) in a welding mode, and the steel pipe filling bodies (22) are made of bubble concrete or concrete with strength not lower than that of the prefabricated piers (1).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810438124.6A CN108643215B (en) | 2018-05-09 | 2018-05-09 | Construction method of anchor pier type foundation after rotary spraying and pressing into variable cross section |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810438124.6A CN108643215B (en) | 2018-05-09 | 2018-05-09 | Construction method of anchor pier type foundation after rotary spraying and pressing into variable cross section |
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| CN108643215A CN108643215A (en) | 2018-10-12 |
| CN108643215B true CN108643215B (en) | 2020-09-01 |
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