CN111691426A

CN111691426A - Comprehensive construction method for non-occluded water stop pile of deep foundation pit drilling support structure

Info

Publication number: CN111691426A
Application number: CN202010474589.4A
Authority: CN
Inventors: 桂林
Original assignee: NO4 CONSTRUCTION Co Ltd OF CHONGQING CONSTRUCTION ENGINEERING GROUP; Chongqing Construction Engineering Group Co Ltd
Current assignee: NO4 CONSTRUCTION Co Ltd OF CHONGQING CONSTRUCTION ENGINEERING GROUP; Chongqing Construction Engineering Group Co Ltd
Priority date: 2020-05-29
Filing date: 2020-05-29
Publication date: 2020-09-22

Abstract

The invention discloses a comprehensive construction method of a non-occluded water stop pile of a deep foundation pit drilling support structure, which relates to the field of deep foundation pit drilling and aims to achieve the purpose, and the technical scheme of the invention comprises the following steps: 1) constructing the 1 st batch of jumping piles of the enclosure structure; 2) drilling a water stop pile in the 2 nd batch of the enclosure structure; 3) excavating a foundation pit; 4) detaching the pile head; 5) and (5) excavating the deep foundation pit. The construction of the secant pile needs to adopt large equipment such as a pipe staggering machine or a rotary drilling rig or adopt a high-pressure rotary spraying outer side water stopping construction method, the cost of mechanical equipment, manual assistance and the like are greatly reduced, and the cost is reduced.

Description

Comprehensive construction method for non-occluded water stop pile of deep foundation pit drilling support structure

Technical Field

The invention relates to a comprehensive construction method of a non-occluded water stop pile of a deep foundation pit drilling support structure, and mainly relates to the field of deep foundation pit drilling.

Background

With the continuous and rapid advance of the construction of basic facilities in China, the construction technology of basic engineering is changed day by day, and the construction of deep foundation pits is more, including underground continuous walls, steel sheet pile supports, cast-in-situ bored piles supports, SMW construction method piles, steel pipe piles supports, anchor cable piles supports and the like, and different support modes are selected according to different geological conditions and surrounding environments. Deep foundation pit construction is carried out in geology such as a sandy gravel stratum or a compact sand layer, steel sheet pile supporting is difficult to insert and beat, and the construction cost of the underground continuous wall is high.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a comprehensive construction method of a non-occluded water stop pile of a deep foundation pit drilling enclosure structure, which reduces the need of using large-scale equipment such as a pipe staggering machine or a rotary drilling rig or using a high-pressure rotary spraying outer side water stop construction method in occluded pile construction, greatly reduces the cost of mechanical equipment, manual assistance and the like, and reduces the cost.

In order to achieve the purpose, the technical scheme of the invention is as follows: the method comprises the following steps: 1) constructing the 1 st batch of jumping piles of the enclosure structure; 2) drilling a water stop pile in the 2 nd batch of the enclosure structure; 3) excavating a foundation pit; 4) detaching the pile head; 5) and (5) excavating the deep foundation pit.

Preferably, the 1 st batch of pile skipping construction of the building enclosure comprises the following steps: A. measuring and positioning and arranging pile holes: the cast-in-place bored piles are arranged around the foundation pit in a circle according to the enclosure structure, the cast-in-place bored piles are firstly constructed by jumping at least 1 pile at intervals, and then cast-in-place piles in the interval area are constructed; B. investigating geological conditions and selecting a drilling machine; C. embedding the steel casing; D. drilling by a drilling machine; E. checking and cleaning the formed holes; F. processing in a reinforcement cage field; G. processing the pile head in a reinforcing cage site with a broken protective sleeve; H. and (5) secondary hole cleaning and pouring.

Preferably, the 2 nd batch of water stop pile drilling of the building envelope comprises the following steps: the cast-in-place bored piles are arranged around the foundation pit in a circle according to the building enclosure, the cast-in-place bored piles are firstly constructed by jumping at least 1 pile at intervals, and then cast-in-place bored piles in the interval area are constructed.

Preferably, excavation of the foundation pit: firstly, constructing a top crown beam, and gradually excavating under working conditions after the strength of the top crown beam meets the design requirement. And (5) stopping excavating when the excavation is 0.5m below each supporting position, hoisting the supporting system, applying a jacking force, and continuing excavating downwards.

Preferably, the pile head is detached: the pile head is detached, firstly, lines are drawn at the cutting position of the pile head and cut by adopting a circular cutting technology, 1-2 cm above the cutting line, hole sites are uniformly and symmetrically arranged on each pile along the periphery of the pile head, a pneumatic pick is used for punching, and the punching depth is the diameter of the pile so as to insert a steel chisel. The driving is carried out symmetrically and horizontally as much as possible so as to ensure that the fracture surface is kept at the same horizontal plane. After drilling is completed, inserting wedge-shaped steel rods, drilling and jacking the broken pile heads, enabling the steel rods to be horizontal or slightly upward, and then knocking the steel rods repeatedly by adopting a sledge hammer to knock back and forth so as to break the concrete at the annular broken pile holes. Each steel chisel is provided with two clamping pieces, and the steel chisel can be taken out conveniently after the pile head is broken. If the wedge-shaped steel rod does not support the concrete, the hoisting rope is lifted by the pre-buried U-shaped lifting hook and the crane. .

Preferably, the deep foundation pit is excavated, namely, a long-arm excavator is used for excavating the foundation pit to a position 100cm below the first layer of waist beam, the first layer of waist beam and the inclined support are constructed, the long-arm excavator is used for excavating the foundation pit to a position 100cm below the second layer of waist beam. And constructing a waist beam and an inclined support at the position of the second inner support, excavating a foundation pit by using a long-arm excavator until the height of the bottom of the bearing platform is 50cm, arranging a water collecting pit at the inner side of the foundation pit, pumping water and constructing a broken stone cushion layer. And (5) checking and accepting the foundation pit, and entering the next procedure after the foundation pit is qualified.

The technical principle and the beneficial effects of the invention are as follows:

the method has the advantages of avoiding the need of a pipe staggering machine or a large rotary drilling rig for the secant pile construction, having low work efficiency and the like, having remarkable treatment effect, improving the construction work efficiency, reducing the labor intensity of workers, providing reference for solving similar engineering construction, having good popularization and application values, reducing the need of using large equipment such as the pipe staggering machine or the rotary drilling rig for the secant pile construction or adopting a high-pressure rotary spraying outer side water stopping construction method, greatly reducing the cost of mechanical equipment, manual assistance and the like, and reducing the cost.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments will be briefly introduced below, it is obvious that the drawings in the following description are only two of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic plan view of a batch-wise bored pile position arrangement according to an embodiment of the present invention;

FIG. 2 is a schematic side view of a pile cleaned by high pressure injection water before construction of pile batch 2 according to an embodiment of the present invention;

fig. 3 is a schematic view of the pile head according to the embodiment of the present invention.

Detailed Description

The technical solutions in the present invention will be described clearly and completely with reference to the accompanying drawings, and it is to be understood that the described embodiments are merely preferred embodiments of the present invention, rather than all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Examples

As shown in fig. 1, the embodiment of the present invention includes the following steps:

1 st batch pile jumping construction of enclosure structure

(1) Measurement positioning and pile hole arrangement

A foundation pit drilling enclosure structure non-occlusive pile water stop construction method is characterized in that bored piles are arranged around a foundation pit in a circle according to a conventional drilling enclosure structure, the construction of the 1 st batch of enclosure piles is generally not in sequence, and the construction of 1 pile at intervals is generally skipped (or the construction of a plurality of piles is skipped), wherein the '0 # or A' piles are firstly used in the following figure, and then the '1 # or B' piles are constructed. The firstly constructed drill drills and pours according to a normal procedure, and the method has no difference with the conventional process and has very simple operation thought. The pile jumping construction mainly depends on the placement of a drilling machine, geological reasons in the drilling process, requirements of post drilling on concrete setting time and other factors.

The general net spacing between the pile position of the first construction and the pile position of the second construction is about 150 mm-300 mm under the condition of @, and the pile position is not too large so as to prevent the influence on the hole cleaning effect. Meanwhile, the influence of diameter expansion caused by geological conditions is considered, and if the diameter expansion phenomenon occurs, a rotary drilling rig is adopted to cut the protruding part of the local pile foundation. In order to reduce the influence on the position of the post-drilled pile, the verticality of the first pile is strictly controlled within 1% in addition to strictly controlling the position of an orifice.

Before construction, the reference points, the level points and the datum lines of the building are checked again, and protective measures are taken. When the pile space is lofted and positioned, a steel nail is knocked in the hard terrace, and a positioning triangle is drawn by red paint to mark the pile number. The control points, the level points and other measurement marks are strictly protected, and the striking marks are made and recorded. Pile position lofting and elevation guiding and measuring can be carried out after self-checking (technical responsible personnel), field supervision, rechecking and acceptance check of construction units are qualified. The integrity of the original measurement record and the technical data are ensured to meet the requirements. The control error is less than +/-5 mm, and the pile position error is less than 20 mm.

(2) Geological condition investigation and selection drilling machine

The pile foundation construction adopts more pore-forming processes aiming at different geological conditions, and the construction process principle is different. Such as: the rotary drilling rig can be suitable for various geological conditions, can adopt a casing follow-up measure in weaker geology, can also realize the drilling of large-diameter rock stratums at present, and only has higher requirements on mechanical equipment; the percussion drilling machine is widely applicable, can be suitable for rock strata, softer strata and the like, and can adopt a forward circulation process and a reverse circulation process for percussion hole forming; the rotary drilling machine is suitable for softer strata, soil containing a small amount of gravel and pebbles, and drilling machines with positive circulation and reverse circulation and the like; the rotary drilling machine can be suitable for large-diameter pile hole construction with large depth.

(3) Embedding steel casing

When the pile casing for drilling is buried, according to the coordinates of the piles in the line given by the construction drawing, the measurement engineer can use the total station to determine the pile position and report the position to the supervision and re-measurement, and then the construction can be carried out.

The wall thickness of a steel pile casing of the drilled pile is 8mm, the pile casing is fixed before the pile casing is embedded, the center of the pile casing and the center of a pile position should coincide, and the deviation is not more than 5 cm. The pile casing is required to be 50cm higher than the ground, the embedding depth is not less than 1.5m, the deviation between the top surface position and the pile center is not more than 5cm, the pile casing is solid and does not leak water, the inner diameter of the pile casing is about 20cm higher than that of a drill bit, the pile casing is preferably higher than the underground water level by 2m and is also required to be 0.5m higher than the ground, the embedding depth meets the construction requirement, and the deviation of the top surface position is not more than 50 mm; the inclination deviation is less than or equal to 1 percent.

(4) Drilling machine drilling

Before construction, a slurry making pool, a slurry pool and a sedimentation pool are arranged between every two piers and are connected by a circulating groove, and the slurry discarded in the construction process cannot be discharged randomly, and is transported outside by a slurry truck and discharged from places permitted by relevant departments. And (4) after the mud pit is excavated, the protective railings around the mud pit are closed and enclosed, a safety warning board is hung, and a red warning lamp is arranged at night.

The slurry can prevent the collapse of the hole wall and inhibit underground water in the construction of the drilling machine, so that the slurry is an important factor for ensuring the stability of the hole wall. The foundation rock soil has silt layer and pebble layer and high ground water level, so that the modulated slurry has important performance indexes. According to the characteristic that the rotary drilling rig is high in drilling speed, high-quality bentonite or chemical polymer is adopted as a raw material of the slurry to make the slurry.

Firstly, before formal drilling, rechecking the pile position and the drilling machine once again without errors, and when the drilling machine is accurately in place, drilling, wherein the drilling speed is controlled to be slowed down once the drilling rod is advanced for about 60cm each time during drilling, the bucket is required to be stably placed and lifted slowly, particularly, the verticality is required to be monitored by a control panel in the 5-8 m section of rotary drilling process of an orifice, and if deviation exists, the verticality is corrected in time.

Secondly, an operator can observe whether the drill rod is vertical at any time and control the drilling depth through a depth counter. When the rotary digging bucket drill bit rotates clockwise to drill, the cutting plate of the bottom plate is aligned with the rear side of the barrel turning plate. The drill chip enters the cylinder body, after the cylinder body is filled with a bucket, the drill bit rotates anticlockwise, the bottom plate is positioned by the positioning block and seals the opening in the bottom, and then the drill bit is lifted to the ground to unload soil.

Thirdly, low-speed drilling is adopted when drilling is started, and the weight of the main winch steel wire rope is not less than 20% of the sum of the weight of the drill rod and the weight of the drilling tool, so that deviation of hole sites is avoided. High-speed drilling can be adopted 3m below the drilling protective cylinder, the drilling speed is related to pressure, the self-weight friction and pressurization of a drill bit and a drill rod are adopted, and the footage speed is 20cm/min under the pressure of 150 MPa; under the pressure of 200Mpa, the footage speed is 30 cm/min; the advancing speed is 50cm/min under the pressure of 260 MPa.

Fourthly, the drilling operation is continuously carried out in shifts, and holes are formed at one time. In the drilling process, construction is carried out according to parameters determined by the test piles, a full-time recorder is arranged to record various parameters in the hole forming process, drilling slag conditions are observed at any time according to geological reports and compared with the geological reports, and accurate sampling is carried out to report the geological conditions to a site supervision engineer. When the geology of the pile tip bearing layer is not in accordance with the design, a supervision engineer and related departments are immediately informed to confirm whether the design is changed or not. Drilling depth, mud indexes, mechanical equipment damage, obstacles, drilling abnormal conditions and the like must be recorded in detail in the drilling process. The recording must be careful, timely, accurate, and clear. And handover records are required to be made when the shift is handed over. The mud and drilling slag produced in the drilling process can be discharged after being purified by a sedimentation tank. The pollution to farmland and surrounding water sources can not be caused in the discharging process, and the sediment in the sedimentation tank is transported to a specified silt abandoning site by an automobile for piling treatment.

After drilling to the designed elevation of the pile hole, the drill bit continues to rotate for several circles on the spot under the condition of no pressurization, and then the drill bit is lifted, so that the over drilling can be avoided under the condition that the drill bit is taken out of slag as much as possible.

When drilling in weak geology, the cast-in-situ bored pile can be solved by adopting casing follow-up, adjusting slurry proportion and changing a pore-forming process. When the second batch of stagnant water stake construction, the first batch of shaping stake position need wash, does not have the hole of collapsing.

(5) Checking and cleaning holes

After the pore-forming, pore-forming inspection is carried out, and the inspection content comprises: hole site center, hole diameter, hole depth, inclination, etc. And after the hole depth is inspected to be qualified, cleaning the hole, or cleaning the hole again. Detecting the central position of the hole position of the formed hole, and measuring the position deviation along the line direction and the vertical line direction by adopting a ruler.

The pore diameter detection of the formed pore can adopt a cage type hole detector or a caliper for detection, the former takes the smooth passing of the hole detector as the standard, and the latter can carry out acceptance inspection according to directly measured data. The pore-forming gradient detection can adopt a cage type hole detecting method or an electronic gradient detection method. The depth of the formed hole is preferably measured directly by using a measuring rope, and the measurement should be carried out along the periphery of the hole.

Cage type hole detecting device detection: the outer diameter of the pile is equal to the designed aperture of the drilled pile, and the length of the pile is equal to 4-6 times of the aperture. During detection, the hole checking device is lifted, the center of the hole is consistent with the lifting steel wire rope, the hole is slowly placed into the hole, and the hole diameter is smooth from top to bottom to show that the hole diameter meets the design requirement.

(6) In-site processing of reinforcement cage

When the reinforcement cage is manufactured, the reinforcement stirrup is manufactured according to the design size, and the position of the main reinforcement is marked. The main ribs are placed on a flat working platform, and the positions of the reinforcing ribs are marked on the main ribs. During welding, the mark of any main rib on the reinforcing rib is aligned with the mark of the reinforcing rib at the middle part of the main rib, the reinforcing rib is righted, the perpendicularity between the reinforcing rib and the main rib is corrected by the wooden right-angle plate, and then spot welding is carried out. After each main rib and all the reinforcing ribs are welded, the framework is rotated, the other main ribs are welded one by one according to the method, and then the spiral ribs are welded. The spiral ribs are arranged according to the requirements of design drawings, and skip welding or skip welding is avoided.

The steel reinforcement cage protective layer adopts mesopore cylindrical concrete cushion, and the cushion diameter is not less than protective layer thickness, and mesopore diameter is greater than the reinforcing bar diameter of wearing 1mm, and the reinforcing bar is worn to the center and is welded on the main reinforcement. The number of the channels is about 4m, and not less than 4 blocks are symmetrically arranged along the circumference of each channel.

(7) Pile head breaking protective sleeve reinforcement cage in-site processing

The steel reinforcement cage protective layer adopts mesopore cylindrical concrete cushion, and the cushion diameter is not less than protective layer thickness, and mesopore diameter is greater than the reinforcing bar diameter of wearing 1mm, and the reinforcing bar is worn to the center and is welded on the main reinforcement. The number of the channels is about 4m, and not less than 4 blocks are symmetrically arranged along the circumference of each channel. After the reinforcement cage framework is manufactured, the construction of the reinforcement cage protective sleeve can be started. The steel reinforcement cage protective sheath can adopt the PVC pipe, and the PVC pipe is suitable according to just passing the main muscle to adopt sponge or foam to wrap at the protective sheath tip, utilize the sticky tape ligature, prevent that grout from leaking into. When the reinforcement cage is transported to the site for storage, square timbers must be supported, a certain distance is needed for storage of the reinforcement cage, and the reinforcement cage is completely covered by the color strip cloth.

(8) Secondary hole cleaning and pouring

The guide pipe with the diameter of 200mm is preferably adopted for the guide pipe installation and the secondary hole-cleaning cast-in-place pile casting, and the total length of the guide pipe is accurately measured during the casting. Checking the sealing performance of the guide pipe, namely checking whether the guide pipe leaks or not and whether the guide pipe is connected with a sealing ring or not. And after the reinforcement cage is installed, the guide pipe is arranged as soon as possible, and hole cleaning is carried out for the second time. When the guide pipe is hung, the guide pipe should be centered, the axis is straight, and the guide pipe is stably sunk, so that the steel reinforcement cage is prevented from being clamped and colliding with the wall of the hole. After the placement is finished, a funnel and a storage hopper are arranged at the upper opening of the guide pipe, the lower opening is about 30cm away from the bottom of the hole, the slurry index is adjusted, the specific gravity of the slurry for secondary hole cleaning is smaller than 1.15, the specific gravity of the slurry returning is smaller than 1.30, the sediment thickness meets the standard requirement, and the hole cleaning time is generally controlled to be about 15-30 min. After secondary hole cleaning is finished, a constructor tests sediments at the bottom of the hole, the thickness of the sediments is smaller than 10cm, and after the sediment thickness control indexes are met, the constructor can check and accept the sediments with a supervision unit, and after the sediments are qualified, the constructor can timely sign and carry out next procedure.

The concrete pouring can adopt a conduit with the diameter of 200mm to carry out underwater concrete pouring. The time from the end of the second clear to the beginning of the perfusion should be controlled within 30 minutes. The concrete pouring quality is controlled according to the following requirements:

commercial concrete is adopted, and the slump of the concrete is controlled to be 18-22 cm. The initial setting time of the concrete is controlled to be 6-8 hours, and the grading sheet is attached along with a vehicle when the concrete is poured. The quality is strictly good, and a graded list must be attached to each batch of entering concrete mixing plant. The site should carefully check the composition of the mix proportion and find the problem to prevent correction in time.

Before the guide pipe is put into the hole, the quality of a connecting screw thread, a welding point and a sealing groove is carefully checked, the number, the measurement and the length are recorded, the height from the bottom opening of the guide pipe to the bottom of the hole is generally controlled to be about 50cm, and the length of the first section of the guide pipe is more than 4 m. And (3) pouring the underwater concrete within 30min after the second hole cleaning, and if the time exceeds 30min, measuring the thickness of the mud at the bottom of the hole again, and if the time does not meet the requirement, cleaning the hole again.

2 nd batch sealing pile drilling of building envelope

The 2 nd pile foundation construction drilling process is the same as that of the previous 2 nd pile foundation construction drilling process, and is different in hole cleaning. In order to ensure that the post-construction pile foundation is effectively contacted with the first batch of construction pile foundation concrete and has an effective waterproof effect, a high-pressure water jetting cleaning process is adopted for the side combination part of the pile foundation, and attachments such as slurry and the like attached to the first batch of piles are washed away. Because the thickness of soil reserved on the existing pile foundation is generally smaller than the net spacing of the piles by 150-300 mm, most of the soil blocks are separated when the second batch of drilled piles are constructed, and the residual high-pressure water jet cleaning can meet the requirement of a joint surface.

The selection of the water jet construction method is different according to the soil condition, and the equipment for sinking the pile by water jet comprises the following steps: water pump, water source, water pipe (bending should be reduced, straight is strived for), jetting pipe, etc. During construction, attention should be paid to timely guiding the water delivery rubber pipe to prevent the water delivery rubber pipe from being broken and falling off; after the foundation pile is inserted, erected and stabilized, the water pressure can be gradually increased to sweep and clean back and forth.

The water jetting replacement construction principle is that high-pressure water is used for cutting and damaging soil bodies on the side of the disturbed pile, attached soil bodies are fully liquefied or washed to form slurry, the liquefied slurry and fine particles are returned to the ground under the action of wind-water linkage, and the cutting, the disturbing, the damaging and the cleaning are repeatedly carried out up and down.

The water injection replacement construction at the position adopts a high-pressure water pump machine tool, an injection pipe is put into a hole, wind and water are started to rise to 0.5-1.0 Mpa and 28-32 Mpa respectively, water is injected from top to bottom, wind and water are lifted up and down in a linkage manner after the hole is finished, the stratum is repeatedly cut and stirred for 3 times, attachments are fully stirred and liquefied under the action of high-pressure water, the replacement area and range are enlarged, and liquefied silt slurry and fine particles are returned to the ground in a wind and water linkage manner.

In the process of water jet replacement, throughWind-water linkage displacement flushing, replacing the liquefied slag hole as a covering layer after the adjacent holes are communicated, determining whether to continue cutting displacement or finish displacement according to the return slag amount of the slag hole and the concentration of returned slurry, wherein the specific gravity of the slag is not more than (or not more than) 1.2g/cm³. And when the replacement hole is constructed and the next hole construction is carried out, the hole is continuously used as a slag hole, and the construction step and the cutting replacement finishing standard are consistent with the construction step.

In order to avoid mutual influence between pile positions after construction and ensure the overall stability and safety of the adjacent fender pile, the pile foundation construction of adjacent holes can be carried out after the strength of the upper hole reaches 70%.

3 digging foundation pit

After the support system of the enclosure structure is constructed, the foundation pit is excavated according to the construction design procedure, the top crown beam is constructed firstly, and after the strength of the crown beam reaches the design requirement, the working condition is divided for gradual excavation. And (5) stopping excavating when the excavation is 0.5m below each supporting position, hoisting the supporting system, applying a jacking force, and continuing excavating downwards.

When the underground water level is higher in the construction process, precipitation assistance can be adopted, the elevation after bottom sealing cannot be higher than the designed elevation of the bottom of the bearing platform, and the top surface of the concrete of the bottom sealing is basically flat.

4 pile head detachment

The pile head is detached, firstly, lines are drawn at the cutting position of the pile head and cut by adopting a circular cutting technology, 1-2 cm above the cutting line, hole sites are uniformly and symmetrically arranged on each pile along the periphery of the pile head, a pneumatic pick is used for punching, and the punching depth is the diameter of the pile so as to insert a steel chisel. The driving is carried out symmetrically and horizontally as much as possible so as to ensure that the fracture surface is kept at the same horizontal plane. After drilling is completed, inserting wedge-shaped steel rods, drilling and jacking the broken pile heads, enabling the steel rods to be horizontal or slightly upward, and then knocking the steel rods repeatedly by adopting a sledge hammer to knock back and forth so as to break the concrete at the annular broken pile holes. Each steel chisel is provided with two clamping pieces, and the steel chisel can be taken out conveniently after the pile head is broken. If the wedge-shaped steel rod does not support the concrete, the hoisting rope is lifted by the pre-buried U-shaped lifting hook and the crane.

Before hoisting, the pile head and the pile body are completely separated, then hoisting is carried out, and the pile head and the pile body are hoisted as lightly as possible so as to avoid damaging the steel bars. The personnel should be far away from the operation range during the hoisting process to prevent the pile head from falling and causing accidents.

And cleaning a construction site, and preparing pile foundation detection and pile head waste building garbage treatment. The pile foundation detection is mainly carried out according to the project type and the acceptance standard.

5 deep foundation pit excavation

And after the construction of the top beam is finished, excavating the foundation pit by using a long-arm excavator according to the design of foundation pit support, excavating to a position 100cm below the first-layer waist beam, and constructing the first-layer waist beam and the inclined support. And (5) excavating the foundation pit by using a long-arm excavator to reach the position 100cm below the second-layer waist beam. And constructing a waist beam and an inclined support at the position of the second inner support. And (3) excavating a foundation pit by using a long-arm excavator until the height of the bottom of the bearing platform is 50cm, arranging a water collecting pit on the inner side of the foundation pit, pumping water and constructing a broken stone cushion layer. And (5) checking and accepting the foundation pit, and entering the next procedure after the foundation pit is qualified.

After the monitoring period is +/-0.000 from the building of the monitoring network to the civil engineering, if various monitoring values have no great change, the monitoring can be finished, and a monitoring report is compiled for 1 month, wherein the specific monitoring period requirement is as follows: monitoring for 2 times by using various monitoring initial values as reference values; the rest are determined according to 7.0.3 in technical Specification for monitoring foundation pit engineering of buildings (GB 50497-2009).

The monitoring frequency of the monitoring project is determined by comprehensively considering the types of the foundation pits, different construction stages of the foundation pits and underground engineering, the surrounding environment, the change of natural conditions and local experience. When the monitored value is relatively stable, the monitoring frequency can be properly reduced.

And (2) jumping out and drilling to reduce mutual influence, constructing 'plain piles', then cutting the plain piles to construct 'meat piles', wherein hard cutting can be carried out according to the construction of conventional underwater cast-in-place piles, constructing the plain piles in a staggered manner, and drilling the meat piles after concrete of the plain piles reach certain strength and the strength difference between two adjacent plain piles is not more than 10% of the designed strength. (2) The occlusion amount is about 20cm generally, in order to ensure that the bottom of the occlusion pile has enough occlusion amount, the position of an orifice is strictly controlled, the verticality of the occlusion pile is strictly controlled within 1 percent, otherwise, the non-occlusion condition is easy to occur, the necking and necking conditions of the pile are easy to occur under the condition of long pile length and poor geological conditions, and the foundation pit wall is leaked due to abnormal occlusion.

1, simple technical principle and strong operability: according to the construction technology, the high-pressure water jet cutter is adopted to remove mud and soil attachments on the side of the cast-in-place pile, newly-poured concrete is recycled to be bonded with the existing pile for water stop, one set of water jet cutter equipment is added to the operation equipment, the use of large equipment such as a pipe staggering machine or a rotary drilling rig is reduced, the problems that similar secant piles need to be controlled in cutting construction, the construction sequence needs to be strictly controlled and the like are solved. The technology only adds one water jet hole cleaning construction process, the construction processes of other pile foundations are completely consistent, and the operation thought is simple.

2, labor is saved, and cost is reduced: the operating equipment of the foundation pit drilling enclosure structure non-occlusive pile water stop construction method is additionally provided with a set of water jet cutter equipment, but the problems that a pipe staggering machine or a rotary drilling rig and other large-scale equipment are required for occlusive pile construction or a high-pressure rotary spraying outer side water stop construction method is adopted are solved, the cutting construction needs to be controlled for similar occlusive piles, the construction sequence needs to be strictly controlled, and the like are solved, the process is complex, and the rotary spraying water stop effect is possibly omitted. The cost of mechanical equipment, manual assistance and the like are greatly reduced, and the cost is reduced.

3, high efficiency, safety and controllability: the foundation pit drilling enclosure structure non-occlusive pile water stop construction method reduces the use of large equipment and improves the efficiency. Avoided the secant pile simultaneously except that the strict control drill way position, still should carry out the strict control to its straightness that hangs down within 1%, otherwise the unoccluded condition appears easily, to the long longer condition of stake, when geological conditions is relatively poor, the necking down and the expansion neck condition of stake appear easily, and the abnormal interlock leads to the foundation ditch wall seepage condition, and the degree of safety improves.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. The comprehensive construction method of the deep foundation pit drilling enclosure structure non-occluded water stop pile is characterized by comprising the following steps of:

1) constructing the 1 st batch of jumping piles of the enclosure structure;

2) drilling a water stop pile in the 2 nd batch of the enclosure structure;

3) excavating a foundation pit;

4) detaching the pile head;

5) and (5) excavating the deep foundation pit.

2. The comprehensive construction method of the deep foundation pit drilling envelope non-occluded water stop pile according to claim 1, characterized in that: the construction of the 1 st batch of jumping piles of the enclosure structure comprises the following steps:

A. measuring and positioning and arranging pile holes: the cast-in-place bored piles are arranged around the foundation pit in a circle according to the enclosure structure, the cast-in-place bored piles are firstly constructed by jumping at least 1 pile at intervals, and then cast-in-place piles in the interval area are constructed;

B. investigating geological conditions and selecting a drilling machine;

C. embedding the steel casing;

D. drilling by a drilling machine;

E. checking and cleaning the formed holes;

F. processing in a reinforcement cage field;

G. processing the pile head in a reinforcing cage site with a broken protective sleeve;

H. and (5) secondary hole cleaning and pouring.

3. The comprehensive construction method of the deep foundation pit drilling envelope non-occluded water stop pile according to claim 2, characterized in that: the drilling of the 2 nd batch of water stop piles of the building envelope comprises the following steps: the cast-in-place bored piles are arranged around the foundation pit in a circle according to the building enclosure, the cast-in-place bored piles are firstly constructed by jumping at least 1 pile at intervals, and then cast-in-place bored piles in the interval area are constructed.

4. The comprehensive construction method of the deep foundation pit drilling envelope non-occluded water stop pile according to claim 1, characterized in that: excavation of a foundation pit: firstly, constructing a top crown beam, and gradually excavating under working conditions after the strength of the top crown beam meets the design requirement. And (5) stopping excavating when the excavation is 0.5m below each supporting position, hoisting the supporting system, applying a jacking force, and continuing excavating downwards.

5. The comprehensive construction method of the deep foundation pit drilling envelope non-occluded water stop pile according to claim 1, characterized in that: pile head detaching: the pile head is detached, firstly, lines are drawn at the cutting position of the pile head and cut by adopting a circular cutting technology, 1-2 cm above the cutting line, hole sites are uniformly and symmetrically arranged on each pile along the periphery of the pile head, a pneumatic pick is used for punching, and the punching depth is the diameter of the pile so as to insert a steel chisel. The driving is carried out symmetrically and horizontally as much as possible so as to ensure that the fracture surface is kept at the same horizontal plane. After drilling is completed, inserting wedge-shaped steel rods, drilling and jacking the broken pile heads, enabling the steel rods to be horizontal or slightly upward, and then knocking the steel rods repeatedly by adopting a sledge hammer to knock back and forth so as to break the concrete at the annular broken pile holes. Each steel chisel is provided with two clamping pieces, and the steel chisel can be taken out conveniently after the pile head is broken. If the wedge-shaped steel rod does not support the concrete, the hoisting rope is lifted by the pre-buried U-shaped lifting hook and the crane. .

6. The comprehensive construction method of the deep foundation pit drilling envelope non-occluded water stop pile according to claim 1, characterized in that: and (3) excavating the deep foundation pit, namely excavating the foundation pit to a position 100cm below the first layer of waist beam by using a long-arm excavator, constructing the first layer of waist beam and the inclined support, excavating the foundation pit to a position 100cm below the second layer of waist beam by using the long-arm excavator. And constructing a waist beam and an inclined support at the position of the second inner support, excavating a foundation pit by using a long-arm excavator until the height of the bottom of the bearing platform is 50cm, arranging a water collecting pit at the inner side of the foundation pit, pumping water and constructing a broken stone cushion layer. And (5) checking and accepting the foundation pit, and entering the next procedure after the foundation pit is qualified.