阅读说明：本技术 一种桩中桩断桩接桩施工方法 (Pile-in-pile broken pile and pile-splicing construction method ) 是由 曾祥茂 李志生 林楚涛 方宏彬 王鹏 叶剑铭 张昭洪 方旭 黄维阳 罗家俊 吴汉 于 2020-07-03 设计创作，主要内容包括：本发明涉及一种桩中桩断桩接桩施工方法,施工流程：场地平整、测量放样、旋挖钻抽芯、加肋钢管制作、焊接、钢筋笼制作、安装、吊装加肋钢管、基底混凝土处理、钢管内侧注混凝土、钢管外侧注水泥砂浆、混凝土养护。本发明不用考虑周边地质环境的影响,最大化利用了既有桩体及抽芯检测过程留下的抽芯孔,本发明的实施过程较传统断桩接桩方法成本较低且施工进度较快。(The invention relates to a pile-in-pile broken pile and pile-connected construction method, which comprises the following construction processes: the method comprises the following steps of leveling a field, measuring and lofting, rotary drilling and core pulling, ribbed steel pipe manufacturing, welding, steel reinforcement cage manufacturing, mounting, hoisting ribbed steel pipes, base concrete treatment, concrete pouring on the inner sides of the steel pipes, mortar pouring on the outer sides of the steel pipes and concrete curing. The method does not need to consider the influence of the surrounding geological environment, and utilizes the existing pile body and the core-pulling hole reserved in the core-pulling detection process to the maximum extent.)

1. A pile-in-pile-breaking and pile-splicing construction method is characterized by comprising the following operation steps:

s1, leveling the field: intensively cleaning the abandoned soil of the construction site, leveling the site, and preparing for measuring lofting and pile splicing;

s2, measurement lofting: the measuring team and team loft out the center position of the pile position according to the parameters of the design drawing, after rechecking by a field technician, the report and supervision engineer checks the position, hands over the team and works in writing, draws a cross line according to the center point of the pile position to lead out the fender pile and protects the fender pile;

s3, rotary drilling and core pulling: after the core drill bit is installed on the rotary excavator, the rotary excavator is moved until the core drill bit is concentric with the foundation pile, operation is started, the foundation pile is crushed through the rotation of the barrel core drill bit with a valve at the bottom and is directly installed in the drill bit, then the drill bit is lifted out of the pipe by the drilling machine lifting device and the telescopic drill rod to unload soil, and the operation is repeated in a circulating mode until the crack of the foundation pile is drilled to be 1500mm below the foundation pile;

s4, manufacturing and installing ribbed steel pipes: the steel pipe is made of Q235c steel, the outer diameter is 1100mm, the wall thickness is 16mm, the length is 12820mm, HRB 400-grade steel hoops with the diameter of 16mm are uniformly arranged on the inner wall and the outer wall of the steel pipe at intervals of 300mm, the steel hoops are welded on the steel pipe by adopting single-side welding, the stirrup joints are welded on two sides, the joint length is not less than 80mm, the allowable deviation of the circumference of a pipe joint of the steel pipe is required to be 40mm, the allowable deviation of the flatness of the pipe end is 10mm, the allowable deviation of the plane inclination of the pipe end is 10mm, the allowable deviation of adjacent pipe diameters is 5mm, and when the pipe joints;

s5, manufacturing and welding a reinforcement cage: in order to ensure the connection between the pile extension part and a bearing platform at the upper part of a foundation pile, a reinforcement cage is welded at the upper part of a steel pipe and extends into the bearing platform, stirrups are added around main reinforcements of the reinforcement cage, one reinforcement is added every 100mm and gradually surrounds to a position of 2200mm from top to bottom, the stirrups adopt HPB 300-grade reinforcements with the diameter of 10mm and are firmly bound with the cross points of stressed main reinforcements, the total length of the stressed main reinforcements is 2200mm, and the rest 1500mm are fixed on the inner wall of the steel pipe by single-side welding;

s6, hoisting the ribbed steel pipe: after the ribbed steel pipe is manufactured, hoisting the ribbed steel pipe into the core-pulling hole by adopting a crawler crane, wherein the insertion depth exceeds that of the crack and is 1500mm downwards, the ribbed steel pipe is hoisted into the hole to be centered and slowly placed to prevent the ribbed steel pipe from colliding with the hole wall, and the ribbed steel pipe is immediately parked when placed down, so that the reason is checked;

s7, treating the base concrete: cleaning small concrete blocks and sand grains on the concrete surface of the foundation pile by using a negative pressure vacuum pump, and smearing a layer of mortar with the same grade before concrete construction to ensure the quality of a pile body and better connect cast-in-place concrete and original concrete;

s8, pouring concrete on the inner side of the steel pipe: c40 concrete which is one label larger than the original foundation pile concrete C35 is poured into the ribbed steel tube by adopting a guide tube method, the concrete is poured continuously in a layered mode, the pouring thickness of each layer is 500mm, the concrete pouring is finished once, an inserted vibrator is adopted for vibrating, the inserted vibrator is required to be deep into the lower layer for 50mm-100mm when the upper layer is poured, the vibration is dense, a vibrating rod cannot directly vibrate the steel tube, and the surface elevation of the poured concrete is required to be more than 800mm higher than the bottom elevation of a designed bearing platform;

s9, grouting cement mortar on the outer side of the steel pipe: selecting a welded steel pipe with the diameter of phi 32mm as a grouting pipe, filling M40 cement mortar into a gap between the steel pipe and a concrete pile body at high pressure by using a high-pressure slurry pump when the grouting pipe reaches the bottom of the gap, vibrating the steel pipe at the same time until the slurry liquid level or the designed elevation of the pile surface is not lower and overflows, and ensuring that the grouting amount is not less than the volume of the gap between the steel pipe and the concrete pile body during construction, and solidifying and maintaining for a period of time to form a pile-in-pile to complete pile extension for a broken pile;

s10, concrete curing: after the concrete is poured, in order to ensure that the poured concrete reaches the strength required by the design within the specified age and prevent the concrete from shrinking, the concrete is covered, moisturized and maintained within 12 hours, and the concrete water-pouring times of the pile connecting are required to keep the concrete in a wet state; the water for curing the concrete is the same as the water for mixing, the water is watered every 2 hours, the earthwork cloth is used for wrapping around the pile, the concrete is sufficiently cured under the condition of no water loss, and the inside of the earthwork cloth is kept wet all the time.

2. A pile-in-pile break-and-pile construction method according to claim 1, characterized in that: and in the step S3, the size of the core bit installed by the rotary excavating machine is 1200mm in diameter.

3. A pile-in-pile break-and-pile construction method according to claim 1, characterized in that: in the step S4, the steel pipe can be manufactured in sections, the steel pipe is welded and lengthened, and the length of each section is determined according to the actual situation.

4. A pile-in-pile break-and-pile construction method according to claim 1, characterized in that: and manufacturing the reinforcement cage in the step S5: HRB 400-grade steel bars with the diameter of 32mm and the length of 3700mm are adopted as the main bars of the steel reinforcement cage and are uniformly distributed on the circumference with the diameter of 1100 mm.

Technical Field

The invention relates to the technical field of drilling and pouring construction, in particular to a pile-in-pile construction method for pile breaking and pile splicing.

Background

As a mature building form, the cast-in-situ bored pile has the advantages of simple construction process, mature technology, easy quality detection and the like, and is widely applied to construction of various bridge pile foundations.

However, in the daily construction of bored piles, sometimes, due to the process problems, the problems of the pouring operation or the influence of external force, it often happens that slurry or gravel enters the cement concrete to separate the poured concrete into an upper section and a lower section, which causes the deterioration of the concrete or the damage of the cross section area to cause the pile breaking accident, so that the pile foundation cannot meet the design stress requirement.

The existing technological method closest to the scheme of the invention mainly has three realization processes:

(1) if the broken pile position is below 10m from the ground surface and the concrete is finally set, the impact drill with the diameter slightly smaller than the inner diameter of the reinforcement cage can be used for performing impact drilling on the original pile position to the position 1m below the bottom opening of the reinforcement cage, then a proper amount of explosive is put into the hole, and the reinforcement cage is integrally lifted out or lifted out one by one after being loosened. And then carrying out secondary hole expansion to the designed diameter, and pouring concrete again after hole cleaning.

(2) If the pile breaking position is within 5m from the ground surface and the geological conditions are good, excavating to the pile breaking position, removing the slurry or the concrete doped with the slurry, exposing the good concrete and chiseling, removing the slurry on the reinforcing steel bars, and then erecting and pouring the concrete. And backfilling and tamping in time after the mold is removed.

(3) If the pile breaking position is within 5m and 10m of the ground surface, or if the geological condition is poor within 5m of the ground surface, concrete pipes or steel pipes with the diameter slightly larger than the pile diameter are connected in a joint mode until the pile breaking position sinks to a position 0.5m below the pile breaking position, the slurry and the concrete mixed with the slurry are removed, a good concrete surface is exposed and roughened, the slurry on the reinforcing steel bars is removed, and then the concrete is poured by taking the concrete pipes or the steel pipes as templates.

The existing technological method closest to the scheme of the invention comprises the following pile splicing construction technological processes: and (3) using an impact drill with the diameter slightly smaller than the inner diameter of the steel reinforcement cage to perform impact drilling at the original pile position to a position 1m below a bottom opening of the steel reinforcement cage, then putting a proper amount of explosive into the hole, and integrally hoisting or hoisting one steel reinforcement cage after the steel reinforcement cage is loosened. And then carrying out secondary hole expansion to the designed diameter, and pouring concrete again after hole cleaning.

The prior technical scheme has the following defects and reasons:

firstly, the process needs to use explosives, and the danger coefficient is higher in the material entering and construction processes. And the scheme must be approved by a public security department, and the procedure is complicated. After the pile is broken by the process, the original pile body must be completely broken and cannot be recycled. And in the secondary pouring process, the surrounding rock stratum is in a broken state, which is not beneficial to the quality control of the pile body.

Secondly, the technology has strict requirements on the periphery of the pile foundation, and if an urban rail tunnel exists near the constructed foundation pile, the technology can possibly damage the urban rail tunnel.

Disclosure of Invention

The invention aims to solve the technical problem of overcoming the defects of the prior art and provides a construction method for pile breaking and pile splicing in a pile.

In order to solve the technical problems, the technical scheme provided by the invention is as follows: a pile-in-pile-breaking and pile-splicing construction method comprises the following construction processes: leveling the site → lofting for measurement → loosing core by rotary drilling → manufacturing ribbed steel tube, welding → manufacturing and installing steel reinforcement cage → hoisting ribbed steel tube → treating base concrete → injecting concrete inside the steel tube → injecting cement mortar outside the steel tube → maintaining concrete.

A pile-in-pile-breaking and pile-splicing construction method comprises the following operation steps:

s1, leveling the field: and intensively cleaning the abandoned soil on the construction site, leveling the site, and preparing for measuring and lofting and pile splicing.

S2, measurement lofting: and (4) lofting the central position of the pile position by a measuring team according to the parameters of the design drawing, rechecking by a field technician, reporting and supervising an engineer for inspection, performing written return operation on the team, drawing a cross line according to the central point of the pile position to lead out the fender pile, and protecting the fender pile.

S3, rotary drilling and core pulling: the diameter of the original foundation pile is 1800mm, and the inner diameter of the reinforcement cage is 1620 mm. After a core bit (with the diameter of 1200mm) is installed on the rotary excavating machine, the rotary excavating machine is moved until the core bit is concentric with the foundation pile, and operation is started. The foundation pile is crushed by the rotation of a barrel type core drill bit with a valve at the bottom, and is directly loaded into the drill bit, then the drill bit is lifted out of the pipe by a drilling machine lifting device and a telescopic drill rod to unload soil, and the steps are repeated in a circulating way, and soil is continuously taken out and unloaded until the drilling reaches 1500mm below the cracks of the foundation pile.

S4, manufacturing and installing ribbed steel pipes: the steel pipe is made of Q235c steel, and has an outer diameter of 1100mm, a wall thickness of 16mm and a length of 12820 mm. In order to ensure the vertical bearing capacity of the steel pipe, increase the initial deflection and joint defects of the steel pipe, increase the bond stress between the steel pipe and the concrete and improve the integrity of the concrete-filled steel pipe, HRB 400-grade steel bar hoops with the diameter of 16mm are uniformly arranged on the inner wall and the outer wall of the steel pipe at intervals of 300mm, and the steel bar hoops are welded on the steel pipe by adopting single-side welding. The stirrup joint adopts double-sided welding, and the length of the joint is not less than 80 mm. The steel pipe can be made in sections, the steel pipe is welded and lengthened, and the length of each section is determined according to actual conditions. The perimeter tolerance of the steel pipe joints is required to be 40mm, the flatness tolerance of the pipe ends is required to be 10mm, the plane inclination tolerance of the pipe ends is required to be 10mm, the tolerance of the adjacent pipe diameters is 5mm, and the tolerance of the edge of the adjacent pipe joints is required to be 3mm when the pipe joints are spliced in an opposite mode.

S5, manufacturing and welding a reinforcement cage: in order to ensure the connection between the pile extension part and the bearing platform at the upper part of the foundation pile, a steel reinforcement cage is welded at the upper part of the steel pipe and extends into the bearing platform. Manufacturing a steel reinforcement cage: HRB 400-grade steel bars with the diameter of 32mm and the length of 3700mm are adopted as the main bars of the steel reinforcement cage and are uniformly distributed on the circumference with the diameter of 1100 mm. And the stirrups are added around the main reinforcement of the steel reinforcement cage, and one stirrup is added every 100mm, and the stirrups gradually encircle to 2200mm from top to bottom. The stirrups adopt HPB 300-grade steel bars with the diameter of 10mm, and are firmly bound with the crossed points of the stressed main bars. The whole length of the stress main reinforcement stirrup setting part is 2200mm, and the rest 1500mm is fixed on the inner wall of the steel pipe by adopting single-side welding.

S6, hoisting the ribbed steel pipe: after the ribbed steel pipe is manufactured, the ribbed steel pipe is hoisted into the core-pulling hole by adopting a crawler crane, the insertion depth exceeds 1500mm downwards of the crack, the ribbed steel pipe is hoisted into the hole and should be centered and slowly placed, the hole wall is prevented from being collided, and the ribbed steel pipe should be immediately parked when being placed down, so that the reason is checked.

S7, treating the base concrete: and cleaning small concrete blocks and sand grains on the concrete surface of the foundation pile by adopting a negative pressure vacuum pump, and smearing a layer of mortar with the same grade before concrete construction in order to ensure the pile body quality and better connect cast-in-place concrete and the original concrete.

S8, pouring concrete on the inner side of the steel pipe: and (3) pouring concrete which is larger than the original foundation pile concrete (C35) by a grade (C40) in the ribbed steel pipe by adopting a conduit method. And (3) carrying out layered continuous pouring on the concrete, wherein the pouring thickness of each layer is 500mm, and the concrete pouring is finished at one time. The steel pipe is vibrated by adopting the inserted vibrator, the inserted vibrator is required to be embedded into the lower layer to a certain depth (50-100 mm) when the upper layer is poured, the vibration is dense, and the vibrating rod cannot directly vibrate the steel pipe. The elevation of the surface of the poured concrete is more than 800mm higher than the elevation of the designed bearing platform bottom.

S9, grouting cement mortar on the outer side of the steel pipe: selecting a welded steel pipe with the diameter of phi 32mm as a grouting pipe, wherein the grouting pipe reaches the bottom of the gap. M40 cement mortar (the original foundation pile concrete is marked as C35) is filled in a gap between the steel pipe and the concrete pile body at high pressure by adopting a high-pressure slurry pump, the steel pipe is vibrated at the same time until the liquid level of the slurry (the designed elevation of the pile surface) is not lower and overflows, the injection speed is slow during construction, and the grouting amount is ensured to be not less than the volume of the gap between the steel pipe and the concrete pile body. Solidifying and maintaining for a period of time to form a pile-in-pile to complete pile extension for the broken pile.

S10, concrete curing: after the concrete is poured, in order to ensure that the poured concrete reaches the strength required by the design within the specified age and prevent the concrete from shrinking, the concrete is covered, moisturized and cured within 12 hours. The watering times of the pile-connecting concrete can keep the concrete in a wet state; the curing water of the concrete is the same as the mixing water, and the concrete is watered every 2 hours. And the geotextile is used for wrapping around the pile, so that the concrete is sufficiently maintained under the condition of no water loss, and the geotextile is kept wet all the time.

The invention has the following advantages: the method has the characteristics that 1, the distance between the pile body crack and the pile top is within 15m in the early stage of application.

2. And (4) core pulling of the rotary drill, moving the rotary drill to the state that the core drill is concentric with the foundation pile after the core drill is installed on the rotary drill, and starting operation. The foundation pile is crushed by the rotation of a barrel type core drill bit with a valve at the bottom, and is directly loaded into the drill bit, then the drill bit is lifted out of the pipe by a drilling machine lifting device and a telescopic drill rod to unload soil, and the steps are repeated in a circulating way, and soil is continuously taken out and unloaded until the drilling reaches 1500mm below the cracks of the foundation pile.

3. And manufacturing and installing the ribbed steel pipe. The steel pipe is made of Q235c steel, and has an outer diameter of 1100mm, a wall thickness of 16mm and a length of 12820 mm. In order to ensure the vertical bearing capacity of the steel pipe, increase the initial deflection and joint defects of the steel pipe, increase the bond stress between the steel pipe and the concrete and improve the integrity of the concrete-filled steel pipe, HRB 400-grade steel bar hoops with the diameter of 16mm are uniformly arranged on the inner wall and the outer wall of the steel pipe at intervals of 300mm, and the steel bar hoops are welded on the steel pipe by adopting single-side welding. The stirrup joint adopts double-sided welding, and the length of the joint is not less than 80 mm.

4. And grouting cement mortar on the outer side of the steel pipe. Selecting a welded steel pipe with the diameter of phi 32mm as a grouting pipe, wherein the grouting pipe reaches the bottom of the gap. M40 cement mortar (the original foundation pile concrete is marked as C35) is filled in a gap between the steel pipe and the concrete pile body at high pressure by adopting a high-pressure slurry pump, the steel pipe is vibrated at the same time until the liquid level of the slurry (the designed elevation of the pile surface) is not lower and overflows, the injection speed is slow during construction, and the grouting amount is ensured to be not less than the volume of the gap between the steel pipe and the concrete pile body.

The method does not need to consider the influence of the surrounding geological environment, and utilizes the existing pile body and the core-pulling hole reserved in the core-pulling detection process to the maximum extent.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Fig. 2 is a cross-sectional view of an embodiment of the present invention.

FIG. 3 is a flow chart of a prior art process closest to the solution of the present invention.

Detailed Description

The present invention will be described in further detail with reference to examples.

A construction method suitable for pile-in-pile breaking and pile splicing is exemplified by bridge engineering (Heijingbridge) which is a first-stage municipal infrastructure project in a violin zone of a central business zone of a Zhuhai Cross door. The engineering bridge pile foundation adopts a D1800 cast-in-place pile as a bridge foundation.

The single pile construction comprises the following raw materials in parts by weight:

before formal construction begins, a core drill bit (the diameter is 1200mm) is installed on the rotary excavating machine, then the rotary excavating machine is moved until the core drill bit is concentric with the foundation pile, and operation is started until the core drill bit drills until the cracks of the foundation pile fall down by 1500 mm. The steel pipe is made of Q235c steel, and has an outer diameter of 1100mm, a wall thickness of 16mm and a length of 12820 mm. HRB 400-grade steel bar hoops with the diameter of 16mm are uniformly arranged on the inner wall and the outer wall of the steel pipe at intervals of 300mm, and the steel bar hoops are welded on the steel pipe by adopting single-side welding.

In order to ensure the connection between the pile extension part and the bearing platform at the upper part of the foundation pile, a steel reinforcement cage is welded at the upper part of the steel pipe and extends into the bearing platform. Manufacturing a steel reinforcement cage: HRB 400-grade steel bars with the diameter of 32mm and the length of 3700mm are adopted as the main bars of the steel reinforcement cage and are uniformly distributed on the circumference with the diameter of 1100 mm. And the stirrups are added around the main reinforcement of the steel reinforcement cage, and one stirrup is added every 100mm, and the stirrups gradually encircle to 2200mm from top to bottom. The stirrups adopt HPB 300-grade steel bars with the diameter of 10mm, and are firmly bound with the crossed points of the stressed main bars. The whole length of the stress main reinforcement stirrup setting part is 2200mm, and the rest 1500mm is fixed on the inner wall of the steel pipe by adopting single-side welding.

And after the ribbed steel pipe is manufactured, hoisting the ribbed steel pipe into the core-pulling hole by adopting a crawler crane. And cleaning small concrete blocks and sand grains on the concrete surface of the foundation pile by adopting a negative pressure vacuum pump, and smearing a layer of mortar with the same grade before concrete construction in order to ensure the pile body quality and better connect cast-in-place concrete and the original concrete.

And (3) pouring concrete which is larger than the original foundation pile concrete (C35) by a grade (C40) in the ribbed steel pipe by adopting a conduit method. And (3) carrying out layered continuous pouring on the concrete, wherein the pouring thickness of each layer is 500mm, and the concrete pouring is finished at one time. The steel pipe is vibrated by adopting the inserted vibrator, the inserted vibrator is required to be embedded into the lower layer to a certain depth (50-100 mm) when the upper layer is poured, the vibration is dense, and the vibrating rod cannot directly vibrate the steel pipe. The elevation of the surface of the poured concrete is more than 800mm higher than the elevation of the designed bearing platform bottom.

Selecting a welded steel pipe with the diameter of phi 32mm as a grouting pipe, wherein the grouting pipe reaches the bottom of the gap. M40 cement mortar (the original foundation pile concrete is marked as C35) is filled in a gap between the steel pipe and the concrete pile body at high pressure by adopting a high-pressure slurry pump, the steel pipe is vibrated at the same time until the liquid level of the slurry (the designed elevation of the pile surface) is not lower and overflows, the injection speed is slow during construction, and the grouting amount is ensured to be not less than the volume of the gap between the steel pipe and the concrete pile body. Solidifying and maintaining for a period of time to form a pile-in-pile to complete pile extension for the broken pile. And finally, maintaining the foundation pile concrete in a heat preservation and moisture preservation manner.

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.