CN109235453B - Deep foundation pit PRC pipe pile assembled supporting method - Google Patents

Abstract

The invention discloses an assembled supporting method of a PRC (prestressed concrete pipe) tubular pile of a deep foundation pit, which comprises the following steps of: 1. construction preparation; 2. PRC tubular pile supporting construction; 3. constructing lattice column vertical piles; 4. constructing a first section steel supporting system: the first layer of H-shaped steel support mainly comprises a main support, a branch support and a shaped steel bracket, wherein the main support and the branch support are welded to form a stable triangular frame, and the end shaped steel bracket is welded with an L-shaped steel plate ring beam to form a first support system; 5. and (3) constructing a second steel support system: the steel shotcrete adopts the steel pipe to make, and the steel encloses the purlin and adopts two pin type steel to make, establishes expansion bolts fixed angle steel bracket on the fender pile of foundation ditch both sides, erects the steel and encloses the purlin. The invention provides the deep foundation pit PRC tubular pile fabricated supporting method which mainly adopts a primary supporting structure consisting of PRC tubular pile supporting piles and H-shaped steel, has high degree of mechanization, accelerates the construction progress, shortens the construction period of foundation pit supporting, does not need slurry retaining walls, and does not produce slurry pollution.

Description

Deep foundation pit PRC pipe pile assembled supporting method

Technical Field

The invention relates to the field of deep foundation pit supporting engineering, in particular to an assembled supporting method for a PRC (prestressed concrete pipe) tubular pile of a deep foundation pit.

Background

At present, in the development and construction of urban high-rise and super high-rise buildings and underground spaces, deep foundation pit excavation and support are one of indispensable important construction modes. The cast-in-situ bored pile row pile support is a common deep foundation pit row pile support form due to the fact that lateral stiffness is large, bending resistance is strong, deformation is relatively small, and therefore protection of surrounding buildings and municipal facilities is facilitated. However, the construction restriction of high requirement on civilized construction environment and tight construction period is often faced in the current municipal engineering construction, and the grouting pile row pile support is easy to cause the phenomenon of slurry cross flow in the construction site during construction, and the construction period is long, so that the overall civilized image and the construction period of the municipal construction site are affected, and the grouting pile row pile support is greatly restricted and restricted in the existing engineering use.

Disclosure of Invention

The invention aims to solve the problems of on-site slurry transverse flow and long construction period in the existing cast-in-situ pile row supporting technology, and provides the deep foundation pit PRC tubular pile assembled supporting method.

In order to achieve the purpose, the technical scheme of the invention is as follows: an assembled supporting method for a PRC pipe pile of a deep foundation pit comprises the following steps:

step 01) construction preparation: leveling a construction site, arranging a measurement control net, accurately determining a pile position, placing a pile driver in position according to a discharged pile position point during pile driving, wherein the deviation of the pile position is not more than 50 mm;

step 02) PRC tubular pile support construction, which comprises the following steps:

a. positioning a drilling machine: the long spiral rotary machine is in place, so that the drill rod is vertically aligned with the center of the pile position, and the verticality deviation of the pile is not more than 1%;

b. drilling to form a hole: when drilling begins, a drill bit valve is closed, a drill rod is moved downwards until the drill bit touches the ground, a motor is started to drill, the speed is slow and the speed is fast, and meanwhile, the deviation of the drilled hole is checked and corrected in time;

c. pile planting: after pile hole construction is finished, a crane is required to be in place immediately, a pipe pile is ready to be hoisted, the pipe pile is a section of pipe pile, after the pipe pile is inserted into a pile position, the pipe pile is inserted for 1.5-2 m, then the pile is vertically stabilized, the verticality deviation is not more than 0.5% when the pile is inserted, if the pile is not vertical in the pile stabilizing process, the pile is corrected in time, and finally a vibration pile driver is adopted to vibrate the pipe pile to the designed elevation;

step 03) constructing lattice columns and upright column piles;

step 04) constructing a first channel type steel supporting system, comprising:

a. excavating earth, spraying and protecting the earth to the original ground, and mounting double-spliced channel steel tie beams at the lattice columns;

b. rectangular strip steel plates are respectively welded with end plates at the tops of the tubular piles to form an L shape, and PRC row piles are connected to form a whole instead of ring beams;

c. the first layer of H-shaped steel support mainly comprises a main support, a branch support and a combined-type steel bracket, wherein the main support and the branch support are welded to form a stable triangular frame, and the combined-type steel bracket at the end part is welded with an L-shaped steel plate ring beam to form a first support system;

step 05) constructing a second steel support system: the steel support is made of steel pipes, the steel enclosing purlin is made of double-spliced steel, expansion bolts are arranged on enclosing piles on two sides of the foundation pit to fix angle steel bracket supports, and the steel enclosing purlin is erected;

and in the step 02), the perpendicularity of the hole is measured by adopting a method of hanging a hanging ball on a drill frame in field control, the perpendicularity of a drill rod can also be controlled by adopting a perpendicularity regulator arranged on the drill, and the site engineering technicians carry out pile position centering and perpendicularity inspection before the construction of each pile. After the requirements are met, drilling can be performed;

in the drilling and pore-forming process in the step 02), when a drill rod is shaken or difficult to drill, the footage should be slowed down to prevent the pile hole from deflecting, displacing and damaging a drilling tool, and according to footage marks on a tower body of the drilling machine, when the pore-forming reaches a designed elevation, the drilling is stopped;

step 02) in the pile planting process, the single pile is corrected in a two-way mode by using a vertical ball, before the pile is inserted, a scale is arranged on the side face of the pile, so that observation and recording in construction are facilitated, and when the pile is inserted to a certain depth and is seriously inclined, a hard plate method cannot be adopted for correction;

the construction quantity of the upright piles is less, cast-in-place piles are adopted, and the construction is synchronous with the tubular piles, and the construction process is concrete: positioning → embedding and protecting a cylinder → drilling → clearing holes → lowering a reinforcement cage → fixing and placing a lattice column → lowering a guide pipe → clearing holes for the second time → measuring holes deep → placing a water-isolating ball → pouring concrete → shifting a drilling machine;

step 05), the steel supporting structure is formed by connecting a fixed end, a movable end and a plurality of sections of steel pipes with different lengths in the middle through a flange plate, and short section steel pipes with different lengths are arranged partially to meet the requirements of the width change of the section of the foundation pit and the length of an inclined strut;

and 05) directly relating the erection time and position of the steel support and the magnitude of the prestress to the stability of the deep foundation pit, and erecting the steel support and applying the prestress according to the regulations when the earthwork is vertically excavated to 50-80 cm below the position of the steel support, so that the enclosure structure receives the support counter-force effect in advance, and the deformation of the enclosure structure is reduced.

Compared with the existing cast-in-place pile supporting technology, the technical scheme of the invention has the following technical effects: the PRC tubular pile assembled supporting method has the advantages of high mechanical construction degree, high construction speed, neat site, short construction period, reliable quality, attractive pile forming appearance and good economic benefit. Compared with the traditional cast-in-place pile support, the method of adopting the PRC tubular pile as the support pile and the first H-shaped steel support to replace the traditional concrete support has the advantages of high construction efficiency and good environmental protection, and is very beneficial to shortening the construction period of the foundation pit and reducing the manufacturing cost.

The PRC tubular pile assembled supporting method for the deep foundation pit overcomes the defects of slurry pollution and slow construction period existing in the pile arrangement supporting construction of the cast-in-place pile, can meet the lateral stiffness and the bending strength required by the deep foundation pit support when applied, does not need slurry to protect the wall, does not produce slurry pollution, and can meet the environmental requirements of civilized construction and shorten the construction period due to the use of the supporting form of the profile steel standard component, and the PRC tubular pile material has relatively low manufacturing cost and saves the engineering cost.

Drawings

FIG. 1 is a construction flow chart of the present invention.

Fig. 2 is a schematic cross-sectional view of a foundation pit according to the present invention.

Fig. 3 is an enlarged view of a partial front view structure at a in fig. 2.

Fig. 4 is a schematic top view of a portion of a structure shown in fig. 2.

Fig. 5 is a partial bottom view of fig. 2 at a.

The labels in the figures are: 1. a section steel corbel; 2. a main support; 3. tying a beam by using channel steel; 4. a second steel support; 5. steel purlin; 6. spraying a protection surface on the tubular pile; 7. a lattice column; 8. PRC tubular pile; 9. a vertical column pile; 10. a tubular pile end plate; 11. a triangular steel plate; 12. section steel; 13. an L-shaped steel plate; 14. branch supporting; 15. the oblique ribbed slab.

Detailed Description

The technical solution of the present invention will be further explained and explained with reference to the drawings and the specific embodiments.

An assembled supporting method for a PRC tubular pile of a deep foundation pit is shown in figures 1, 2, 3, 4 and 5, in the embodiment, a supporting pile of the foundation pit is a PRC tubular pile 8, and a first supporting form is H400 multiplied by 13 multiplied by 21 section steel. The first H400 multiplied by 13 multiplied by 21 section steel main support 2 is connected with the PRC tubular pile through a section steel corbel 1, and the 7 parts of the lattice column are connected through a double-spliced 40a channel steel tie beam 3; the second steel support 4 acts on the PRC tubular pile 8 through the steel purlin 5, and the steel purlin is tightly attached to the tubular pile spraying protection surface 6. The section steel bracket consists of three triangular steel plates 11 with the length of 450 multiplied by 20 and H390 multiplied by 300 multiplied by 10 multiplied by 16 section steel 12, and the section steel bracket is welded with the tubular pile end plate 10 through an L-shaped steel plate 13 and is used as a connecting supporting point of the H400 multiplied by 13 multiplied by 21 section steel support and the PRC tubular pile. The H400 multiplied by 13 multiplied by 21 section steel support and two H400 multiplied by 200 multiplied by 8 multiplied by 13 section steel support 14 are welded by the oblique rib plate 15 to form a stable triangle form. Wherein, the branch support is erected on the steel bracket and welded on the L-shaped steel plate on the top of the end plate 10, and the main support is welded with the L-shaped steel plate through H390 multiplied by 300 multiplied by 10 multiplied by 16 steel.

The supporting method of the embodiment mainly comprises the following steps:

step 01) construction preparation stage: and (4) leveling the construction site, arranging a measurement and control net and accurately determining the pile position. When in piling, the pile driver is put in place according to the pile position discharged, the pile position for piling is accurate, the pile body is vertical, and the deviation of the pile position is not more than 50 mm.

Step 02) PRC tubular pile support construction, which comprises the following steps:

a. positioning a drilling machine: after the long spiral rotary machine is in place, the drill rod is vertically aligned with the center of the pile position, and the allowable deviation of the verticality of the pile is ensured to be not more than 1%. The field control adopts a method of hanging a ball on a drill frame to measure the verticality of the hole, and can also adopt a drilling machine with a verticality regulator to control the verticality of a drill rod; and (4) carrying out pile position centering and verticality inspection by site engineering technicians before construction of each pile. After the requirements are met, drilling can be performed;

b. drilling to form a hole: when the drilling starts, the valve of the drill bit is closed, the drill rod is moved downwards until the drill bit touches the ground, the motor is started to drill, the speed is slow and then the speed is fast, and meanwhile, the deviation of the drilling is checked and corrected in time. When the drill rod is found to shake or be difficult to drill in the hole forming process, the footage should be slowed down to prevent the pile hole from deflecting, displacing and damaging a drilling tool. And stopping drilling when the formed hole reaches the designed elevation according to the footage mark on the tower body of the drilling machine.

c. Pile planting: after the PRC tubular piles are transported to the site from a tubular pile factory, stacking the PRC tubular piles according to the site conditions, checking the appearance quality of the whole number of the prefabricated tubular piles entering the site, and not receiving the tubular piles which do not meet the requirements;

after the pile hole construction is finished, the crane should be in place immediately, the tubular pile is ready to be hoisted, the tubular pile adopts a section of tubular pile, the tubular pile is inserted into the pile position to a certain depth, then the pile is vertically stable, the single pile is corrected in a two-way mode by using a vertical ball, and the verticality deviation when the pile is inserted cannot exceed 0.5%. Before the pile is inserted, a scale is arranged on the side surface of the pile, so that observation and recording in construction are facilitated, and when the pile is found to be not vertical and needs to be corrected in time in the pile stabilizing process, the pile is not suitable to be corrected by adopting a hard plate method when the pile is inserted to a certain depth and is seriously inclined; and finally, vibrating the tubular pile to the designed elevation by adopting a vibrating pile driver.

Step 03) lattice column and lattice column stud construction:

the construction quantity of the lattice column vertical column piles is less, and cast-in-place piles are still adopted and can be constructed synchronously with the tubular piles. The concrete construction process comprises the following steps: positioning → embedding protective cylinder → drilling → clearing hole → lowering steel reinforcement cage → fixing and placing lattice column → lower conduit → secondary clearing hole → depth of hole measurement → placing water isolation ball → pouring concrete → displacement of drilling machine. The quantity of the upright post piles is small, so that the produced slurry is little, the influence on the construction surrounding environment is small, and the construction period is not influenced due to the small quantity of the upright post piles.

Step 04) constructing a first channel type steel supporting system, comprising:

a. excavating earth, spraying and protecting the earth to 1.3m below the ground, and mounting double-spliced 40a channel steel tie beams at lattice columns;

b. rectangular strip steel plates with the width of 500mm and the thickness of 20mm are respectively welded with an end plate at the top of the tubular pile to form an L-shaped steel plate, and the PRC row piles are connected to form a whole instead of ring beams;

c. the first layer of H-shaped steel support mainly comprises a main support H400 multiplied by 12 multiplied by 21, a branch support H400 multiplied by 200 multiplied by 8 multiplied by 13 and a combined-shaped steel bracket, wherein the main support and the branch support are welded to form a stable triangular frame, and the combined-shaped steel bracket at the end part is welded with an L-shaped steel plate ring beam to form a first support system.

Step 05) constructing a second steel support system:

the steel support adopts a phi 609 multiplied by 16mm steel pipe, and the horizontal spacing of the standard section cross braces is 3.6 m; the steel purlin is H400 multiplied by 200 multiplied by 8 multiplied by 13 double-spliced steel; and (4) arranging expansion bolts on the fender piles on two sides of the foundation pit to fix angle steel bracket supports, determining the bracket distance according to the fender pile distance, and erecting a steel purlin.

The steel supporting structure is designed by connecting a fixed end, a movable end and a plurality of sections of steel pipes with different lengths in the middle through flange plates, the length of each section is determined according to specific conditions, and short section steel pipes with different lengths are partially arranged to meet the requirements of the width change of the section of the foundation pit and the length of an inclined strut; the steel support is processed in a factory in sections, and is transported to a construction site by adopting a flat trailer for on-site splicing.

The time and the position of erecting the steel support and the magnitude of the prestress are directly related to the stability of the deep foundation pit; when the earthwork is vertically excavated to about 50cm below the steel support, the steel support is erected in time and prestress is applied according to the specification, so that the enclosure structure receives the support reaction in advance, and the deformation of the enclosure structure is reduced.

This embodiment PRC tubular pile is finished product pile, has higher bending resistance and shear resistance, can directly use after transporting to the scene, and area is little, the narrow and small place construction of municipal administration of being convenient for. In addition, the construction progress of tubular pile is fast, and required mechanical equipment is few, and need not the mud dado, when accelerating the construction progress, has solved bored concrete pile mud overflow, the problem of arranging outward, has guaranteed the clean and tidy of construction site. The use of the standard H-shaped steel supporting component can increase the reuse rate of the supporting material, the assembly is simpler, more convenient and faster, the construction time of foundation pit supporting is reduced, the construction period occupied by excavation of the foundation pit supporting is shortened, the construction period of the whole project is shortened, and great construction period value is created.

Claims (1)

1. The deep foundation pit PRC pipe pile assembled supporting method is characterized by comprising the following steps of: the supporting method comprises the following steps:

the foundation pit support pile is a PRC pipe pile, and the first support form is H400 multiplied by 13 multiplied by 21 section steel; the first H400 multiplied by 13 multiplied by 21 section steel main support is connected with the PRC tubular pile through a section steel corbel, and the lattice column is connected through a double-spliced 40a channel steel tie beam; the second steel support acts on the PRC tubular pile through the steel purlin, and the steel purlin is tightly attached to the spray protection surface of the tubular pile; the section steel bracket consists of three 450 multiplied by 20 triangular steel plates and H390 multiplied by 300 multiplied by 10 multiplied by 16 section steel, the section steel bracket is welded with the end plate of the tubular pile through an L-shaped steel plate and is used as a connecting and supporting point of the H400 multiplied by 13 multiplied by 21 section steel support and the PRC tubular pile, the H400 multiplied by 13 multiplied by 21 section steel support and two H400 multiplied by 200 multiplied by 8 multiplied by 13 section steel branch supports are welded through oblique rib plates to form a stable triangle form, wherein the branch supports are erected on the section steel bracket and are welded on the L-shaped steel plate at the top of the end plate, and the main support is welded with the L-shaped steel plate through the H390 multiplied by 300 multiplied by;

step 01) construction preparation: leveling a construction site, arranging a measurement control net, accurately determining a pile position, placing a pile driver in position according to a discharged pile position point during pile driving, wherein the deviation of the pile position is not more than 50 mm;

step 02) PRC tubular pile support construction, which comprises the following steps:

a. positioning a drilling machine: the long spiral rotary machine is in place, so that the drill rod is vertically aligned with the center of the pile position, and the verticality deviation of the pile is not more than 1%;

b. drilling to form a hole: when drilling begins, a drill bit valve is closed, a drill rod is moved downwards until the drill bit touches the ground, a motor is started to drill, the speed is slow and the speed is fast, and meanwhile, the deviation of the drilled hole is checked and corrected in time;

c. pile planting: after pile hole construction is finished, a crane is required to be in place immediately, a pipe pile is ready to be hoisted, the pipe pile is a section of pipe pile, after the pipe pile is inserted into a pile position, the pipe pile is inserted for 1.5-2 m, then the pile is vertically stabilized, the verticality deviation is not more than 0.5% when the pile is inserted, if the pile is not vertical in the pile stabilizing process, the pile is corrected in time, and finally a vibration pile driver is adopted to vibrate the pipe pile to the designed elevation;

step 03) constructing the upright post piles and the lattice columns;

step 04) constructing a first channel type steel supporting system, comprising:

a. excavating earth, spraying and protecting the earth to the original ground, and mounting double-spliced channel steel tie beams at the lattice columns;

b. rectangular strip steel plates are respectively welded with end plates at the tops of the tubular piles to form an L shape, and PRC row piles are connected to form a whole instead of ring beams;

c. the first layer of H-shaped steel support mainly comprises a main support, a branch support and a combined-type steel bracket, wherein the main support and the branch support are welded to form a stable triangular frame, and the combined-type steel bracket at the end part is welded with an L-shaped steel plate ring beam to form a first support system;

step 05) constructing a second steel support system: the steel support is made of steel pipes, the steel enclosing purlin is made of double-spliced steel, the enclosure piles at two sides of the foundation pit are provided with expansion bolts to fix angle steel bracket supports, the steel enclosing purlin is erected,

in the step 02), the perpendicularity of the hole is measured by adopting a method of hanging a hanging ball on a drill frame in field control, the perpendicularity of a drill rod can also be controlled by adopting a perpendicularity regulator arranged on the drill, and a field engineer carries out pile position centering and perpendicularity inspection before the construction of each pile, so that the drill can be cut after the requirements are met;

in the drilling and pore-forming process in the step 02), when a drill rod is shaken or difficult to drill, the footage should be slowed down to prevent the pile hole from deflecting, displacing and damaging a drilling tool, and according to footage marks on a tower body of the drilling machine, when the pore-forming reaches a designed elevation, the drilling is stopped;

step 02) in the pile planting process, the single pile is corrected in a two-way mode by using a vertical ball, before the pile is inserted, a scale is arranged on the side face of the pile, so that observation and recording in construction are facilitated, and when the pile is inserted to a certain depth and is seriously inclined, a hard plate method cannot be adopted for correction;

the construction quantity of the upright piles is less, cast-in-place piles are adopted, and the construction is synchronous with the tubular piles, and the construction process is concrete: positioning → embedding and protecting a cylinder → drilling → clearing holes → lowering a reinforcement cage → fixing and placing a lattice column → lowering a guide pipe → clearing holes for the second time → measuring holes deep → placing a water-isolating ball → pouring concrete → shifting a drilling machine;

step 05), the steel supporting structure is formed by connecting a fixed end, a movable end and a plurality of sections of steel pipes with different lengths in the middle through a flange plate, and short section steel pipes with different lengths are arranged partially to meet the requirements of the width change of the section of the foundation pit and the length of an inclined strut;

and 05) directly relating the erection time and position of the steel support and the magnitude of the prestress to the stability of the deep foundation pit, and erecting the steel support and applying the prestress according to the regulations when the earthwork is vertically excavated to 50-80 cm below the position of the steel support, so that the enclosure structure receives the support counter-force effect in advance, and the deformation of the enclosure structure is reduced.

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