CN117802975A

CN117802975A - Bored pile construction method for shallow foundation oversized straight pier of complex stratum

Info

Publication number: CN117802975A
Application number: CN202311429445.7A
Authority: CN
Inventors: 陈瑞; 杨义松; 李雷; 陈琳
Original assignee: Shanghai Baoye Construction Engineering Co ltd; Shanghai Baoye Group Corp Ltd
Current assignee: Shanghai Baoye Construction Engineering Co ltd; Shanghai Baoye Group Corp Ltd
Priority date: 2023-10-31
Filing date: 2023-10-31
Publication date: 2024-04-02

Abstract

The invention relates to a bored pile construction method of a shallow foundation oversized straight pier of a complex stratum; the method comprises the following steps of 1, ascertaining geology and defining a construction process flow; step 2, stratum lithology analysis; step 3, measuring and positioning; step 4, burying a protective cylinder; step 5: positioning a drilling machine; step 6: drilling holes; step 7, determining rock entering; step 8, final hole forming, acceptance checking and cleaning Kong Laozha; step 9, secondary acceptance; step 10, manufacturing a reinforcement cage; step 11, lower reinforcement cage; step 12: pouring underwater concrete; step 13, pulling the protective cylinder; step 14: backfilling hole sites; step 15: and (5) repeating the steps 3-14 to finish the foundation construction of all the enlarged diameter piers. The invention realizes the primary quality improvement of the bored pile under complex geological conditions through the process control of the working procedures of pile casing installation, rotary digging, slurry wall protection pore-forming, reinforcement cage manufacturing and hoisting, concrete pouring and the like, and the application of pile foundation sediment control technology, and the quality of the pile foundation reaches the standard.

Description

Bored pile construction method for shallow foundation oversized straight pier of complex stratum

Technical Field

The invention relates to the technical field of pile foundation construction, in particular to a bored pile construction method of a shallow foundation oversized straight pier of a complex stratum.

Background

The traditional rotary drilling bored concrete pile is mostly an independent dry operation construction process and is mostly suitable for mountain areas or stable geographical environments of rock and soil. For plain geographic environment, wet operation construction technology exists, and the time consumption of the forward and reverse circulation pore-forming construction technology in wet operation is long, so that the construction period is influenced; the slurry has great influence on the environment, and a large number of slurry tanks need to be constructed; the multi-construction operation environment of the matched equipment is not well planned; the collapse of the pile foundation is difficult to control, and the collapse pile foundation needs to be backfilled again until the soil is compact so as to take the hole again; often, only the regional pile foundation rock entering is judged through a geological survey drawing, the stratum lithology and distribution cannot be judged correctly, and the control accuracy of the construction process can be greatly enhanced by the application of BIM model technology; for pile foundations with large diameters, the pile diameter is large, so that the control of hole collapse is difficult in the process of large contact area of a pile body, and the slurry retaining wall is not applicable; the pile foundation drill bit is big, and the difficult is salvaged to pile foundation slagging.

Disclosure of Invention

The invention aims to overcome the defects, and provides a construction method of a rotary drilling bored pile with an oversized diameter for a shallow foundation of a complex stratum, which is characterized in that the construction method effectively isolates the influence of unfavorable rock stratum and deep groundwater by effectively connecting construction and process quality control of construction procedures such as surface earth excavation, pile casing embedding, rotary drilling, reinforcement cage manufacturing, concrete pouring and the like, and realizes the primary optimization of pile foundation construction quality, and mainly uses the technologies such as BIM stratum analysis, shallow earth excavation, pile casing enlarging measures, drill bit enlarging measures, rock-soil process judgment, sediment process cleaning quality control and the like as technical supports to avoid the quality problems such as pile foundation construction hole collapse, slag inclusion, sediment overthickness, concrete non-compaction and the like from influencing the pile foundation pile forming quality.

In order to achieve the above object, the present invention is achieved by:

a bored pile construction method for shallow foundation oversized straight piers of complex stratum comprises the following steps of

Step 1, ascertaining geology and defining construction process flow

1) The pier foundation bearing layer is made of apoplexy granite, excavation construction is firstly carried out on surface earthwork to form a shallow foundation working surface, the average pier length is guaranteed to be about 4.5m, for the position where the local apoplexy bearing layer is shallower after excavation, after practical construction, the pier foundation with the effective pier length less than or equal to 1 meter is only perforated, a reinforcement cage is not placed, concrete is not placed, and holes are backfilled after the rock entering is judged through perforation inspection; after large-area excavation of earthwork, a pick machine is adopted to repair the bottom, and plain concrete is used for pouring to the designed pier top elevation;

2) For pier foundations with effective pier lengths exceeding 1 meter, the construction process flow is as follows: excavating surface earthwork, measuring and lofting, burying a steel casing, positioning a drilling machine, drilling, checking holes, judging rock entering and final hole acceptance, manufacturing a reinforcement cage, hoisting, hole cleaning, concrete pouring, backfilling holes and acceptance;

step 2, stratum lithology analysis

Determining the rock layer elevation of each region through BIM (building information modeling) land exploration soil layer lithology model analysis, calculating the pile casing insertion depth requirement and the pile body length estimated value, dividing small construction operation partitions at the same time, and reasonably arranging the operation time of each partition;

Step 3, measuring and positioning

Each pile position is fixed by GPS according to the design requirement, and the specific method is as follows:

according to the data of the building measurement control network and the basic plane layout diagram, the pile position axis grid control network and the elevation datum point are measured, according to pile foundation coordinates, the pile position is measured directly by using a GPS, short steel bars are used for nailing, four control points are arranged around the pile position so as to check and check the pile position at any time, after the axis piles and the pile position lines are put well, self-checking is carried out, then constructors of a construction unit and a supervision unit need to carefully check the pile position lines, check procedures are carried out in time, the pile position lines are led out from each axis, the allowable deviation is 1cm, the pile position lines and marks need to be checked frequently, and the pile position lines need to be repaired in time when the pile position lines are not seen clearly;

before starting work, measuring the elevation of a construction site by using a water level gauge, calculating an average value to serve as the elevation of the hard terrace, and measuring the elevation of the hard terrace near the pile casing after the pile casing is buried, so as to control the pore-forming depth;

step 4, burying a protective cylinder

1) Because the underground water level is higher, according to a geological survey report and the expert demonstration opinion of engineering piles of the project, a steel pile casing needs to be buried to penetrate through a broken pebble layer to enter strong wind for at least 2 meters, hole collapse is reduced, because the pier foundation pier length is shorter, the steel pile casing with enough length is configured on site in combination with the geological survey report to be arranged on the top surface of a bedrock as far as possible, the steel pile casing is coiled by a steel plate with the thickness of 18mm, the diameter is the same as the diameter of the designed pier, the lengths are different from 3 meters, 4.5 meters and 6 meters, a pile casing top ring is welded by a thickened steel ring, the pile casing and the edge are not deformed when being driven and pulled, and the steel pile casing is constructed by a driving stage, namely a vibrating hammer;

2) When the pile casing is buried, the center position of the steel pile casing is determined; the deviation between the center of the pile casing and the center of the pier position is not more than 50mm, and the inclination of the pile casing is not more than 0.5%;

special requirements of the steel casing:

1. the wall thickness of the steel casing is determined according to the power of the vibrating hammer and the side friction generated by the casing entering soil, and the wall thickness of the steel casing is generally manufactured by adopting high-quality steel plates with the thickness of more than or equal to 18 mm;

2. the lower part of the steel protective cylinder is preferably provided with a cutting edge of an inner opening, so that the resistance of the protective cylinder to be lowered is reduced, and the protective cylinder is ensured to be smoothly lowered in place;

3. the vibrating hammer clamps the protective cylinder, and the locking device locks the rear protective cylinder which can be lifted, so that the use is safe and controllable;

4. when the pile casing cannot sink due to dead weight, the vibrating hammer is started to press and sink, if resistance cannot sink, the pile casing cannot be forced to press by continuing to operate after the reason is found, the pile casing is prevented from being damaged due to curling or bending of the lower edge of the pile casing, and mud enters the pile body in the later pile casing pulling process to cause mud clamping of the pile body;

step 5: drilling machine in place

Firstly, ensuring that foundation under a drilling machine does not sink, leveling, compacting and paving a steel plate on the ground, adjusting a drill rod vertically when the drilling machine is in place, then checking whether the center of a newly-defined pier is coincident with the center of a drill bit after a pile casing is embedded, and adjusting the position of the drilling machine if the deviation is large, so as to ensure that the center of a drilled hole meets the design requirement;

Step 6: drilling holes

1) Before the drill is started, the application and the test are applied, and the drill can be started after the diameter of the drill bit, the centering of the drilling machine and the horizontal inspection and acceptance are qualified by a supervision engineer;

2) When drilling, the speeds of the drill bit lifting and falling are uniform, the drilling operation must be continuously carried out without excessive or sudden speed change, and drilling construction records are filled in detail, and when the drilling is stopped due to the reasons, the drill bit is lifted out of the hole, so that the buried drilling is prevented;

3) The hole forming is carried out in a jump digging mode, the condition of the final hole is that the rock entering is not less than 0.5 m, the engineering bearing layer is a apoplexy bedrock, and the comparison and confirmation of the rock scraps of the overlying strong weathering rock stratum should be noted; meanwhile, the top surface of the bearing layer fluctuates greatly, and the depth of the whole section of the pier body entering the lowest point of the top surface of the rock stratum is ensured to meet the design requirement during construction;

step 7, determining rock entering

Sampling and testing are required when a bearing stratum is designed, related personnel are applied to judge the rock, if the rock is difficult to enter in the middle, a drill bit with the diameter of 1.2m is replaced to guide a hole, and then the drill bit with the diameter of 1.6m is changed to continue to form the hole;

step 8, final hole and pore forming acceptance

1) According to the design requirement: controlling the final hole condition according to the depth of entering the bearing layer, wherein the depth of the pier body entering the lower point of the complete rock surface of the bearing layer is not less than 500mm; after entering the rock to reach the design depth, replacing a slag-drawing drill bit to clear holes, wherein the sediment at the bottom of the holes meets the requirements, applying for related personnel to check holes, and measuring the hole depth by a supervision engineer, wherein the detection method comprises the following steps: measuring at least two different positions by using a measuring rope, wherein the measured value is not less than the depth of a designed hole, and after the measured value is qualified, the drill can be lifted; then checking hole sites, aperture and inclination;

2) Inclination degree: lowering the hole detector to the bottom of the hole, simultaneously recovering the position of the drilling design center, measuring the horizontal distance between the steel wire rope of the suspended hole detector and the pier design center from the transverse bridge direction and the forward bridge direction, dividing the horizontal distance value by the hole depth to obtain the inclination, wherein the inclination is not more than 1%;

3) Hole site: the hole detector is lowered to the bottom opening of the protective barrel, the center position of the drilling design is restored, the horizontal distance between the steel wire rope of the hanging hole detector and the design center is measured from the transverse bridge direction and the forward bridge direction, and the deviation is not more than 5cm;

4) Pore diameter: measuring an orifice by using a steel ruler, or adopting a circular hole explorator, and enabling the hole explorator to smoothly descend to the bottom of the hole, wherein the aperture is qualified;

step 8, clearing Kong Laozha

The flat barrel drill bit is replaced to clear Kong Laosha, so that the thickness of sediment at the bottom of a hole meets the design requirement, and the sediment is punched through a guide pipe by adopting a high-pressure high-power water pump to clean if the hole depth is deeper and the sediment is not cleaned by adopting the flat barrel drill for wet operation and the design requirement cannot be met according to the hole depth and the underground water level condition; aiming at the situation that some holes are deeper, if the sediment is cleaned by adopting a flat head sand scooping hopper and cannot meet the design requirement, the sediment is pumped by adopting a water pump, and the sediment is cleaned by adopting auxiliary manpower on the premise of ensuring the safety of personnel;

Step 9, secondary acceptance

Re-checking sediment and hole depth before placing the steel reinforcement cage, so as to ensure the quality control;

step 10, manufacturing a reinforcement cage

1) The steel bars are selected to have quality assurance certificates, and qualified steel bars are rechecked by sampling;

2) The average pier length of the engineering pier foundation is 4.5m, and the raw materials of the steel bars are purchased to be 9m and 12 m; when the reinforcement cage is processed, proper reinforcement raw material specifications are selected, so that the number of reinforcement welded joints is prevented from being increased and reinforcement is prevented from being wasted; the reinforcement cage is manufactured by a full-time reinforcement worker and a licensed electric welder on duty, samples and inspects the lap welding quality of the reinforcement, the sampling number is the same specification of the same welder, a group of 300 welding joints are manufactured, and a test according to the design requirement is designed;

3) The manufacturing of the reinforcement cage meets the design requirement, the pier length is determined according to the hole forming depth, and then the whole root manufacturing or sectional manufacturing mode is adopted; the processing of the steel bars is strictly carried out according to the related parameters of the construction drawing; the reinforcement cage is formed to have straight main reinforcement, small error and round stirrup, and has good visual effect;

4) In order to ensure that the reinforcement cages have enough protection layers, each reinforcement cage is provided with three groups of cushion blocks, each group of cushion blocks is not less than three, and the cushion blocks of the protection layers adopt round concrete precast blocks;

5) 2 hanging bars are welded at the upper part of the reinforcement cage, the hanging bars are symmetrically arranged, the reinforcement cage is made of phi 8 reinforcement bars, and the other ends of the hanging bars are welded into a ring for hoisting, and the length of the hanging bars is less than or equal to 2.7m so as to hoist the reinforcement cage;

step 11, lower reinforcement cage

Because the pier length is shorter, the reinforcement cage extension does not exist; the processed reinforcement cage is put down by adopting a vibrating hammer, and the reinforcement cage can be lifted by means of a tower crane if the installation of the tower crane is completed; the construction sequence of the reinforcement cage is lifting, righting, lowering and righting rechecking;

step 12: pouring underwater concrete

(1) Catheter for placement

In order to effectively ensure the concrete pouring quality, a conduit method is adopted for pier-based concrete pouring, the diameter of the conduit is 300mm, the conduit connection is smooth, smooth and airtight, no water leakage is caused, and a pressure test is carried out before concrete pouring. The pipes are connected section by using a flange plate, a rubber gasket and bolts, and are lowered section by section, the height between the lower opening of the guide pipe and the hole bottom is controlled to be 40+/-5 cm, and the height between the upper opening of the guide pipe and the hole opening is controlled to be 200+/-15 cm; connecting the funnel to the upper opening of the guide pipe after the guide pipe is installed, and integrally hanging the funnel on a drilling frame;

repeated twisting and downward collision are not easy to happen in the process of hoisting the reinforcement cage access hole; the reinforcement cage must be sunk to the bottom and cannot be hung;

After the catheter is placed, carrying out secondary hole cleaning, wherein the thickness of sediment at the bottom of the hole is not more than 50mm;

(2) Concrete pouring

Before the concrete is poured, various detection devices are inspected to be embedded, the concrete pouring is continuously carried out, for example, the concrete pouring has to be intermittent due to reasons, and the concrete pouring is intermittentThe time of the initial setting of the concrete is not exceeded;

immediately pouring concrete after hole cleaning: the maximum grain diameter of coarse aggregate is not more than 40mm and not more than 1/3 of the minimum distance between the minimum steel bars, the sand content is 40% -50%, medium coarse sand is selected, and the slump is controlled to be 180-220 mm; mixing concrete by a professional commodity concrete mixing plant, and transporting the commodity concrete truck to the site for self-unloading; retarder is added according to the actual situation of the site when necessary so as to ensure the quality of the concrete;

the concrete pouring progress is preferably controlled within the initial setting time of the concrete; the guide pipe is a steel guide pipe, the length of the pipe joint is 0.5m, 1.0m, 2.5m, 3.0m, 4.0m and 6.0m, the pipe diameter is 250mm, the thickness of the steel pipe is 3mm, and the steel pipe is formed by connecting flange plates with water-stopping rubber gaskets through bolts. After assembly, ensuring the distance from the bottom of the guide pipe to the bottom of the hole to be 0.3-0.5 m so as to facilitate smooth discharge of the waterproof bolt and extrusion of sediment when concrete is poured; the catheter needs to be overhauled before being used, the pressure is tested by water with the pressure of 0.6-1.0 mpa, and the catheter can be used after being qualified; when the conduit is sunk, checking whether the connection of the conduit is firm and compact so as to prevent air leakage and slurry leakage from affecting the concrete pouring quality;

The quantity of the first poured concrete can meet the requirements that the first embedding depth of the guide pipe is more than or equal to 0.8m and the bottom of the guide pipe is filled; the bottom end of the guide pipe is buried below the concrete surface and is generally kept 2-4 m and not more than 6m and not less than 1m, because the too small buried depth can cause slurry on the concrete surface to be rolled into the concrete to form a mud clamping, or the bottom end of the guide pipe is lifted out of the concrete surface to cause pier breaking, and the too large guide pipe can cause the concrete to be easily blocked, or the guide pipe can not be pulled out; the bottom end of the guide pipe is strictly forbidden to be lifted to the concrete surface, the lifting speed of the guide pipe is controlled, and special persons are arranged to measure the embedded depth of the guide pipe and the height difference of the concrete inside and outside the guide pipe and record the embedded depth;

when the concrete is poured, the conduit can be kept at a slightly larger burial depth, and the pouring speed is slowed down, so that the impact force of the concrete is reduced, and the steel reinforcement cage is prevented from floating upwards; when the reinforcement cage has a certain burial depth in the concrete, then properly lifting the guide pipe, and pouring the concrete at a normal speed; the concrete over-grouting height is 0.5m, and the grouting is manually chiseled for 100cm, so that the exposed pier top concrete is ensured to reach the designed strength grade. Pier body filling coefficients are 1.15-1.2; a group of test blocks are arranged on each square meter of the pier foundation every time 50 square meters are poured;

before pouring underwater concrete, filling a relevant detection form for checking the conditions of the pier foundation and the reinforcement cage, and filling an underwater concrete pouring record in the process of pouring the underwater concrete;

The concrete pouring must be continuously operated, and the pouring interruption is strictly forbidden. The construction preparation and auxiliary facilities are needed before pouring, and effective measures are immediately taken and records are also made once accidents such as machine tool faults or power failure, water cut-off, pipe blockage, water inflow and the like occur;

the concrete is ensured to be continuously supplied in the pouring process; the rotary digging process has the advantages that the hole forming is faster, concrete pouring is needed to be carried out within 4 hours after the cage sinking, the influence of collapse holes and sediment on the pier forming quality is avoided, in order to ensure that concrete reaches the site pouring in time, the concrete is appointed by a concrete provider along with notification and material distribution, and a special concrete tank truck is provided for the foundation construction of the engineering pier for transportation;

controlling the pouring quantity of the concrete at the last time, not making the pier top be too high or too low, adopting a measuring hammer to determine the height of the concrete surface, and controlling the height to be 1.0m above the designed pier top elevation, so that the floating slurry generated in the pouring process is completely extruded out of the pier top; according to piersThe diameter and the filling coefficient are not more than 1.2;

step 13, lifting the protective cylinder

After the concrete is poured to meet the requirements, the vibrating hammer equipment is repositioned, the pile casing is symmetrically pulled out of the pier hole by adopting a double machine, and the pile casing is recycled;

pulling out a protection barrel control key point:

in the process of pulling out the pile casing, the vibrating hammer is operated at a constant speed, so that the concrete compactness is prevented from being reduced due to the fact that the pulling-out speed is too high, pier holes are easily formed when the pier center is pulled out too fast, and the pier body quality is influenced;

The pile casing is pulled out to be kept vertical, and is completed under the command of constructors, so that the perpendicularity of the pile casing is ensured, and the phenomenon that the pier body is partially clamped with mud due to the change of the perpendicularity of the pile casing is prevented;

step 14: hole site backfill

After the pier foundation construction is completed, backfilling original soil into the hole by using a digging machine, wherein the backfilling surface is about 20cm higher than the original ground, and using colored flags as well for enclosure and marking;

step 15: and (5) repeating the steps 3-14 to finish the foundation construction of all the enlarged diameter piers.

The sediment cleaning device in the bored pile construction method of the ultra-large straight pier of shallow foundation of the complex stratum is characterized in that: it comprises a bottom plate connecting part, a rock sediment crushing part and a rock sediment collecting part. The bottom plate connecting part is connected with the bottom plate of the sediment collecting barrel through welding, and the rock sediment crushing part is welded on two sides of the bottom plate connecting part in a mutually perpendicular mode by 2 high-strength steel plates. The rock sediment collecting part consists of 2 pentagonal steel plates, and 2 right-angle sides of the pentagonal steel plates are respectively connected with the sediment collecting barrel bottom plate and the rock sediment crushing part by welding;

when the drill bit rotates, firstly, the rock sediment breaking part breaks the rock for the first time, and as the drill bit continuously descends, the rock sediment breaking part breaks the rock for the second time, and meanwhile, the drill bit rotates to collect the broken rock sediment into the sediment collecting barrel.

The sediment cleaning device of drilling bored concrete pile of big straight mound, its characterized in that: the rock sediment crushing part adopts a blade made of high-strength steel.

The invention provides a construction method of a rotary drilling bored concrete pile with an oversized diameter for a shallow foundation of a complex stratum, which effectively connects construction and process quality control through construction procedures such as surface earth excavation, pile casing embedding, rotary drilling, reinforcement cage manufacturing, concrete pouring and the like, effectively isolates the influence of unfavorable strata and deep groundwater, and realizes primary optimization of pile foundation construction quality. Firstly, excavating the earthwork on the surface layer of a foundation, and controlling the depth of an unfavorable soil layer of a hole formed by the enlarged diameter pile foundation after the excavation is completed. Secondly, the construction process is to expand the construction of the pile casing and the wall, isolate unfavorable soil layers and underground deep water, control the length of the pile casing at the same time, and adopt the construction of hole forming of a rotary drilling bit for expanding the diameter of the rotary drilling bit; before construction, fully utilizing BIM technology to effectively analyze the rock-soil stratum, establishing a partition, block and layer diagram through a model, accurately judging the length of a pile casing to be used, simultaneously realizing comparison of the theoretical pile length and the actual pile length, distinguishing pile forming positions with different depths, selecting proper pore-forming points, and optimizing unnecessary points; the pile casings are all driven into a shallow soil layer formed after excavation, are directly inserted into the surface of the rock layer, only a single pore-forming process of dry pore-forming is needed, the influence of excessive environmental factors is not needed to be considered, the increase of the sediment quantity caused by hole collapse is effectively avoided, the rock-soil performance is analyzed in the process, a pore-cleaning drill bit and a cleaning Kong Pinshu are reasonably selected, and a method for manually measuring the sediment depth and manually cleaning the sediment to assist in mechanical pore cleaning can be adopted for forming the shallow foundation pore; the construction period is short, the construction process is not influenced by the site and weather conditions, a mud pool in the site is not required to be constructed, and the environmental pollution caused by outward transportation and discharge of mud is reduced; the pore-forming process has less mechanical equipment requirements, the single-block area machinery of the site can increase investment, and the construction period is quickened.

In the rotary drilling construction, the method mainly controls the surface layer earthwork excavation depth, and then controls the hole collapse of the pore-forming rock stratum as a main cutting point, so as to strengthen the process construction and the sediment quality control as assistance, ensure the pile forming quality, and improve the judging capability of the construction site process through advanced BIM technology application. In construction, pile forming construction quality of the complex stratum is effectively improved, economic analysis and comparison are facilitated, meanwhile, construction period is saved, cost is saved, environment is protected, limitation of conditions of the environment is avoided, and construction organization is convenient.

Drawings

FIG. 1 is a schematic view of the positioning of a casing during the construction process of the present invention.

FIG. 2 is a schematic view of a sediment removal assembly.

Detailed Description

The invention is further illustrated by the following specific examples.

Step 1, ascertaining geology and defining construction process flow

step 2, stratum lithology analysis

step 3, measuring and positioning

step 4, burying a protective cylinder

special requirements of the steel casing:

step 5: drilling machine in place

step 6: drilling holes

step 7, determining rock entering

step 8, final hole and pore forming acceptance

step 8, clearing Kong Laozha

step 9, secondary acceptance

step 10, manufacturing a reinforcement cage

6) Manufacturing standard of the reinforcement cage:

sequence number	Project	Tolerance (mm)	Remarks
				1	Diameter of reinforcement cage	±10	Outer diameter of main rib
2	Length of reinforcement cage	±100
				3	Distance between main ribs	±10	Center linear distance of main reinforcement
4	Stirrup spacing	±20
				5	Protective layer	±20	Starting from the outer rib of the main rib

Step 11, lower reinforcement cage

step 12: pouring underwater concrete

(1) Catheter for placement

In order to effectively ensure the concrete pouring quality, the pier foundation concrete pouring adopts a conduit method, and the diameter of the conduit is 300mmThe connection of the guide pipe is straight, smooth, airtight and watertight, and the pressure test is carried out before the concrete is poured. The pipes are connected section by using a flange plate, a rubber gasket and bolts, and are lowered section by section, the height between the lower opening of the guide pipe and the hole bottom is controlled to be 40+/-5 cm, and the height between the upper opening of the guide pipe and the hole opening is controlled to be 200+/-15 cm; connecting the funnel to the upper opening of the guide pipe after the guide pipe is installed, and integrally hanging the funnel on a drilling frame;

(2) Concrete pouring

Checking that various detection devices are embedded before concrete pouring, and continuously pouring the concrete, wherein the intermittent time is not longer than the initial setting time of the concrete if the concrete has to be intermittent for reasons;

the concrete pouring progress is preferably controlled within the initial setting time of the concrete; the guide pipe adopts a steel guide pipe, and the length of the pipe joint is 0.5m, 1.0m and 2.5m,3.0m, 4.0m, 6.0m, 250mm pipe diameter and 3mm steel pipe thickness, and is formed by connecting flange plates with water-stopping rubber mats by bolts. After assembly, ensuring the distance from the bottom of the guide pipe to the bottom of the hole to be 0.3-0.5 m so as to facilitate smooth discharge of the waterproof bolt and extrusion of sediment when concrete is poured; the catheter needs to be overhauled before being used, the pressure is tested by water with the pressure of 0.6-1.0 mpa, and the catheter can be used after being qualified; when the conduit is sunk, checking whether the connection of the conduit is firm and compact so as to prevent air leakage and slurry leakage from affecting the concrete pouring quality;

controlling the pouring quantity of the concrete at the last time, not making the pier top be too high or too low, adopting a measuring hammer to determine the height of the concrete surface, and controlling the height to be 1.0m above the designed pier top elevation, so that the floating slurry generated in the pouring process is completely extruded out of the pier top; according to the diameter of the pier, the filling coefficient is not more than 1.2;

step 13, lifting the protective cylinder

pulling out a protection barrel control key point:

The pile casing is pulled out vertically under the command of constructorsThe verticality of the pile casing is ensured, and the local mud clamping of the pier body caused by the change of the verticality of the pile casing is prevented;

step 14: hole site backfill

Sediment cleaning device in drilling bored concrete pile construction method of super large straight mound of complicated stratum shallow foundation, its characterized in that: it comprises a base plate connecting part 1, a rock sediment crushing part 2 and a rock sediment collecting part. The bottom plate connecting part 1 is connected with the bottom plate of the sediment collecting barrel through welding, and the rock sediment crushing part is welded on two sides of the bottom plate connecting part 1 in a mutually perpendicular mode by 2 high-strength steel plates. The rock sediment collecting part 3 consists of 2 pentagonal steel plates, and the 2 right-angle sides of the pentagonal steel plates are respectively connected with the sediment collecting barrel bottom plate and the rock sediment crushing part 2 through welding;

The rock sediment crushing part adopts a blade made of high-strength steel.

The sediment cleaning device can be used for effectively smashing rock and soil sediment for 2 times, so that the volume of the rock sediment is reduced, the smashed rock sediment is pushed into the sediment collecting barrel by means of the thrust of the rotation of the drill bit, the sediment hole cleaning effect of the rock and soil sediment is effectively improved, the sediment thickness of a pile hole is reduced, and the pouring quality is further improved.

Claims

1. A bored pile construction method of a shallow foundation oversized straight pier of a complex stratum is characterized by comprising the following steps: comprising

Step 1, ascertaining geology and defining construction process flow

step 2, stratum lithology analysis

step 3, measuring and positioning

step 4, burying a protective cylinder

special requirements of the steel casing:

step 5: drilling machine in place

step 6: drilling holes

step 7, determining rock entering

step 8, final hole and pore forming acceptance

step 8, clearing Kong Laozha

The flat barrel drill bit is replaced to clear Kong Laosha, so that the thickness of sediment at the bottom of a hole meets the design requirement, and the sediment is punched through a guide pipe by adopting a high-pressure high-power water pump to clean if the hole depth is deeper and the sediment is not cleaned by adopting the flat barrel drill for wet operation and the design requirement cannot be met according to the hole depth and the underground water level condition; aiming at the situation that some holes are deeper, if the sediment is cleaned by adopting a flat head sand scooping hopper and cannot meet the design requirement, the sediment is pumped by adopting a water pump, and the sediment is cleaned by adopting auxiliary manpower on the premise of ensuring the safety of personnel; the sediment cleaning device can also be used for cleaning sediment;

step 9, secondary acceptance

step 10, manufacturing a reinforcement cage

Step 11, lower reinforcement cage

step 12: pouring underwater concrete

(1) Catheter for placement

(2) Concrete pouring

the quantity of the first poured concrete can meet the requirements that the first embedding depth of the guide pipe is more than or equal to 0.8m and the bottom of the guide pipe is filled; the bottom end of the conduit is buried below the concrete surface for 2-4 m, which should not be larger than 6m and not smaller than 1m, because the too small buried depth can cause the slurry on the concrete surface to be rolled into the concrete to form a clamp The concrete surface is lifted out from the bottom end of the mud or the guide pipe to cause pier breaking, and the concrete is easy to block the pipe or the guide pipe cannot be pulled out if the concrete is too large; the bottom end of the guide pipe is strictly forbidden to be lifted to the concrete surface, the lifting speed of the guide pipe is controlled, and special persons are arranged to measure the embedded depth of the guide pipe and the height difference of the concrete inside and outside the guide pipe and record the embedded depth;

The concrete is ensured to be continuously supplied in the pouring process; the rotary digging process has the advantages that the hole forming is faster, concrete pouring is needed to be carried out within 4 hours after the cage is settled, the collapse hole and sediment are prevented from influencing the pier forming quality, the concrete can be ensured to arrive at the site for pouring in time, the concrete is appointed by a concrete provider along with notification and material distribution, and the concrete is used for the workerThe construction of the pier foundation is equipped with special concrete tank truck transportation;

step 13, lifting the protective cylinder

pulling out a protection barrel control key point:

Step 14: hole site backfill

2. The sediment cleaning device in the bored pile construction method of the shallow foundation oversized straight pier of the complex stratum according to claim 1, which is characterized in that: it comprises a bottom plate connecting part (1), a rock sediment crushing part (2) and a rock sediment collecting part. The bottom plate connecting part (1) is connected with the bottom plate of the sediment collecting barrel through welding, and the rock sediment crushing part is welded on two sides of the bottom plate connecting part (1) through 2 high-strength steel plates in a mutually perpendicular mode; the rock sediment collecting part (3) consists of 2 pentagonal steel plates, and 2 right-angle sides of the pentagonal steel plates are respectively connected with a sediment collecting barrel bottom plate and the rock sediment crushing part (2) through welding;

3. The sediment cleaning device of bored pile of big straight mound of claim 2, characterized in that: the rock sediment crushing part adopts a blade made of high-strength steel.