CN113463622A - CFG pile prefabricated pile cap hole reserving grouting construction method - Google Patents
CFG pile prefabricated pile cap hole reserving grouting construction method Download PDFInfo
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/223—Details of top sections of foundation piles
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D15/00—Handling building or like materials for hydraulic engineering or foundations
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D15/00—Handling building or like materials for hydraulic engineering or foundations
- E02D15/02—Handling of bulk concrete specially for foundation or hydraulic engineering purposes
- E02D15/04—Placing concrete in mould-pipes, pile tubes, bore-holes or narrow shafts
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D2250/00—Production methods
- E02D2250/003—Injection of material
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Abstract
The disclosure relates to the technical field of building construction, in particular to a CFG pile prefabricated pile cap hole reserving grouting construction method. The prefabricated pile cap hole-reserving grouting construction method of the CFG pile comprises the steps of reserving a grouting hole and a groove on a prefabricated pile cap, hoisting the prefabricated pile cap above the CFG pile after chiseling and cleaning the pile head of the CFG pile, putting down the groove reserved on the prefabricated pile cap after aligning the pile head of the CFG pile, installing the prefabricated pile cap in place, grouting non-shrinkage grouting material from the reserved grouting hole on the prefabricated pile cap after installing the prefabricated pile cap in place, leveling the grouting material by self gravity and filling a contact surface gap between the pile head of the CFG pile and the prefabricated pile cap and the reserved grouting hole on the prefabricated pile cap so as to ensure that the pile head of the CFG pile and the prefabricated pile cap can be integrally combined together and play a role in transferring foundation stress; compared with a cast-in-place pile cap construction method, the construction quality can be better ensured, the requirement of the construction period is ensured, and the cast-in-place pile cap construction method has the characteristics of high construction speed, relatively simple process, easy quality control and the like.
Description
Technical Field
The disclosure relates to the technical field of building construction, in particular to a CFG pile prefabricated pile cap hole reserving grouting construction method.
Background
The CFG pile is a full-scale cement fly ash gravel pile, is a high-bonding-strength pile formed by mixing mixtures such as cement, fly ash, broken stone, stone chips or sand with water, has the advantages of high foundation bearing capacity, small settlement deformation, good manufacturability, stability, quickness, simplicity and easiness in construction, lower construction cost and the like, and is widely applied to the treatment and reinforcement of the foundation of a weak stratum in the engineering field. The CFG pile composite foundation technology has the characteristics of high construction speed, relatively simple process, easy quality control, low engineering cost and the like, and is well applied to hydraulic engineering. According to the actual conditions of a construction site and the requirements of the construction period, a CFG pile composite foundation treatment technology is adopted in a weak stratum, namely a foundation treatment method for forming a composite foundation by adding water into a mixture of cement, fly ash, broken stone, stone chips or sand and the like and mixing to form a high-bonding-strength pile and forming the composite foundation by the pile, soil among piles and a mattress layer.
In order to ensure the pile top of the CFG pile to diffuse foundation stress, the pile top of the CFG pile is more and more in a form that a pile head of the CFG pile is provided with a pile cap. The pile cap construction of the CFG pile generally adopts a mode of cast-in-place concrete pile cap, specifically, the construction is carried out by adopting a shaped steel template or template on site, the site is cleaned firstly during the construction, and the measurement group is paid off on site firstly, so that the line of the pile cap is ensured to be attractive; then erecting a steel mould; and after the steel die is erected, pouring concrete, and vibrating by using a vibrating rod to remove air bubbles in the concrete. The quality of concrete is strictly controlled in the construction process, and the concrete quality standard used by the pile cap is carried out according to the standard requirements. The following points need to be paid attention to the construction of the CFG pile cast-in-place pile cap: (1) coating a release agent in the steel template; (2) the size of the cast-in-place pile cap needs to meet the design requirement; (3) in winter, heat preservation is required to be carried out, so that concrete is prevented from being frozen; the summer maintenance adopts watering coverage, and the winter adopts wrapping maintenance. The whole CFG pile cap cast-in-place construction process is relatively complex, the concrete curing time is long, the CFG pile cap cast-in-place construction process needs cross construction with other work operations (such as pile soil removal after the CFG pile is formed, pile cap vertical steel mould, pile cap concrete tamping curing and the like), the mutual interference is large, the construction is inconvenient, and the work period is long.
In addition, the pile cap construction of the CFG pile also adopts a prefabricated pile cap mode, before the prefabricated pile cap construction of the CFG pile, the pile head of the CFG pile is cut off, the pile head is cleaned up, then a layer of cement mortar is uniformly coated on the pile head, the prefabricated pile cap is hung above the pile head by a crane after the mortar is coated, the groove reserved below the pile cap is aligned with the pile head and then is put down, and the gap between the pile cap and the pile body is manually filled after the hoisting is finished. However, the surface of the pile head of the CFG pile after the pile head of the CFG pile is cut off has the conditions that the quality of the CFG pile is affected, such as unevenness or edge angle loss and the like, only common cement mortar is adopted for leveling and paving a layer, the quality requirement of the pile head of the CFG pile cannot be met, the firmness and the reliability of connection between the prefabricated pile cap and the pile head of the CFG pile cannot be ensured, and therefore the reinforcing effect of the CFG pile on the foundation is affected.
Disclosure of Invention
In order to solve the technical problems or at least partially solve the technical problems, the present disclosure provides a CFG pile precast pile cap hole-reserving grouting construction method.
The invention provides a construction method for grouting prefabricated pile caps of CFG piles by reserving holes, which comprises the following steps:
after the CFG pile is formed, excavating soil between piles;
after the excavation of the soil between the piles is finished, chiseling the pile heads of the CFG piles;
step three, prefabricating a pile cap of the CFG pile: the precast pile cap is formed by pouring concrete, and a grouting hole and a groove are reserved on the precast pile cap after pouring, wherein the groove is formed at one end part of the precast pile cap, and the grouting hole is communicated with the groove bottom wall of the groove;
hoisting the prefabricated pile cap above the CFG pile, putting down a groove reserved on the prefabricated pile cap after aligning with the pile head of the CFG pile, and installing the prefabricated pile cap in place;
and fifthly, after the prefabricated pile cap is installed in place, grouting material is poured into the prefabricated pile cap from a reserved grouting hole, the grouting material adopts non-shrinkage grouting material, and the non-shrinkage grouting material automatically levels and fills a gap between the pile head of the CFG pile and the prefabricated pile cap and the reserved grouting hole in the prefabricated pile cap by means of dead weight.
Optionally, in the third step, a plurality of grouting holes are reserved in the precast pile cap; and in the fifth step, grouting materials are sequentially injected from a plurality of grouting holes according to a preset grouting sequence, grouting construction operation is sequentially carried out, one grouting hole serves as an exhaust hole in the grouting construction process, and the grouting hole serving as the exhaust hole is filled with the grouting material after the other grouting holes are filled.
Optionally, in the third step, five grouting holes are reserved in the precast pile cap, and the five grouting holes include a central grouting hole and four side grouting holes, the central grouting hole is arranged at the central part of the precast pile cap, and the four side grouting holes are symmetrically arranged on two sides of the central grouting hole in pairs; and in the fifth step, grouting construction operation is sequentially performed according to the sequence of the edge grouting holes firstly and the central grouting holes secondly, wherein the central grouting holes are used as exhaust holes in the grouting construction process, and after the four edge grouting holes are filled, the central grouting holes are filled with grouting materials.
Optionally, in the third step, the diameter of the grouting hole is 30 mm.
Optionally, in the fifth step, when grouting construction operation is performed, grouting material is slowly and uniformly poured into the grouting holes reserved in the precast pile cap until the grouting material flows out from the outer side edge of the precast pile cap, so that the grouting material is ensured to fill the whole grouting holes.
Optionally, in the fifth step, in the grouting construction process, if a water seepage phenomenon is found on the surface of the precast pile cap, a small amount of CGM dry material is distributed, and water is sucked; and if the grouting material flows out from the outer side edge of the precast pile cap, temporarily blocking and compacting the grouting material by using sand until the grouting material is not leaked.
Optionally, in the third step, the cross-sectional shape of the groove reserved on the precast pile cap is a circle, the diameter of the groove is greater than the diameter of the pile head of the CFG pile, and the difference between the two is in the range of 10mm to 20 mm.
Optionally, after the pile heads of the two pairs of CFG piles are chiseled in the above step, the pile head surface of the chiseled CFG pile is chiseled, so that the pile head surface of the CFG pile is flat.
Optionally, after the pile head surface of the chiseled CFG pile is subjected to chiseling treatment, the pile head surface of the CFG pile is cleaned with clear water, and the pile head surface of the CFG pile is ensured to be sufficiently wet.
Optionally, when the excavation of soil between piles is carried out in the first step, firstly, an excavator is adopted to excavate to 10cm above the pile top elevation of the CFG pile, then, the manual excavation is adopted to clear up the pile top elevation of the CFG pile, and then, a tamping machine is adopted to tamp and level the foundation soil so as to achieve the condition of using the CFG pile cutting machine to cut the pile.
Compared with the prior art, the technical scheme provided by the embodiment of the disclosure has the following advantages:
the CFG pile prefabricated pile cap hole reserving grouting construction method provided by the disclosure comprises the steps of reserving grouting holes in prefabricated pile caps of CFG piles, hoisting the prefabricated pile caps above the CFG piles after chiseling and cleaning pile heads of the CFG piles are finished, putting down reserved grooves in the prefabricated pile caps after aligning with the pile heads of the CFG piles, and installing the prefabricated pile caps in place; after the prefabricated pile cap is installed in place, grouting material is poured into the prefabricated pile cap from a reserved grouting hole, grouting construction operation is carried out, the grouting material automatically levels and fills a gap between the pile head of the CFG pile and the prefabricated pile cap and the reserved grouting hole in the prefabricated pile cap by means of self-weight of the grouting material, so that the pile head of the CFG pile and the prefabricated pile cap can be completely combined together to play a role in transferring foundation stress, and the self-leveling grouting material fills the gap between the pile head of the CFG pile and the prefabricated pile cap and the reserved grouting hole in the prefabricated pile cap. Compared with a construction method of a CFG pile cast-in-place pile cap, the construction method of the CFG pile prefabricated pile cap hole reserving grouting can effectively solve a series of problems brought by the cast-in-place pile cap, can complete pile cap prefabrication in a prefabrication factory, can intervene in advance when a CFG pile is constructed, does not occupy the construction period, is synchronously carried out in the prefabrication factory, only needs to hoist the prefabricated pile cap in place on site and carry out grouting construction operation, can create favorable conditions for the follow-up procedure intervention construction in advance, has short construction period, and can save a large amount of labor; the construction method can guarantee the quality of the project, guarantees the requirement of the construction period, has the characteristics of high construction speed, relatively simple process, easy quality control, low construction cost of the project and the like, is favorable for environmental protection, and has great popularization value.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure.
In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present disclosure, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.
Fig. 1 is a schematic flow chart of a construction method for grouting holes in a prefabricated pile cap of a CFG pile according to an embodiment of the present disclosure;
fig. 2 is a schematic cross-sectional view of a CFG pile composite foundation according to an embodiment of the disclosure;
fig. 3 is a schematic structural diagram of pile cap construction by using the CFG pile prefabricated pile cap hole-reserving grouting construction method according to the embodiment of the present disclosure;
FIG. 4 is a schematic cross-sectional structural view of a precast pile cap in an embodiment of the present disclosure;
fig. 5 is a schematic bottom view of a precast pile cap according to an embodiment of the present disclosure.
Wherein, 1-CFG pile; 2, prefabricating a pile cap; 201-grouting holes; 202-grooves; 3-grouting material; 4-undisturbed soil; 5-roadbed filling; 6-two layers of geogrids; 7-a gravel cushion layer; 8-embankment under the foundation bed; 9-bedding layer; 10-graded broken stone on the surface layer of the foundation bed.
Detailed Description
In order that the above objects, features and advantages of the present disclosure may be more clearly understood, aspects of the present disclosure will be further described below. It should be noted that the embodiments and features of the embodiments of the present disclosure may be combined with each other without conflict.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure, but the present disclosure may be practiced in other ways than those described herein; it is to be understood that the embodiments disclosed in the specification are only a few embodiments of the present disclosure, and not all embodiments.
The CFG pile composite foundation is generally a composite foundation formed by CFG piles, pile soil and mattress layers, and in order to ensure the diffusion of the pile tops of the CFG piles to the foundation stress, the pile tops of the CFG piles are increasingly in a form that pile heads of the CFG piles are provided with pile caps. As shown in fig. 2, a schematic cross-sectional view of a CFG pile composite foundation is shown, wherein a pile cap is arranged on the top of the CFG pile. However, the pile cap construction of the existing CFG pile generally adopts a form of cast-in-place concrete pile cap, the process of the cast-in-place construction process of the pile cap of the CFG pile is relatively complex, the concrete curing time of the pile cap is long, the pile cap and other work types need to be constructed in a crossed manner, the mutual interference is large, the construction is inconvenient, and the work period is long. Based on the above, the embodiment of the disclosure provides a construction method for grouting a hole in a prefabricated pile cap of a CFG pile, which can effectively solve a series of problems caused by cast-in-place pile caps, can better ensure the engineering quality and guarantee the requirement of a construction period, and has the characteristics of high construction speed, relatively simple process, easy quality control, low construction cost and the like.
As shown in fig. 1, an embodiment of the present disclosure provides a CFG pile precast pile cap hole-reserving grouting construction method, including the following steps:
after the CFG pile is formed, excavating soil between piles;
after the excavation of the soil between the piles is finished, chiseling the pile heads of the CFG piles;
step three, prefabricating a pile cap of the CFG pile: the precast pile cap is formed by pouring concrete, and a grouting hole and a groove are reserved on the precast pile cap after pouring, wherein as shown in fig. 4, the groove 202 is formed at one end of the precast pile cap 2, and the grouting hole 201 is communicated with the groove bottom wall of the groove 202;
hoisting the prefabricated pile cap above the CFG pile, putting down a groove reserved on the prefabricated pile cap after aligning with the pile head of the CFG pile, and installing the prefabricated pile cap in place;
and fifthly, after the prefabricated pile cap is installed in place, grouting material is poured into the prefabricated pile cap from a reserved grouting hole, the grouting material adopts non-shrinkage grouting material, and the non-shrinkage grouting material automatically levels and fills a gap between the pile head of the CFG pile and the prefabricated pile cap and the reserved grouting hole in the prefabricated pile cap by means of dead weight.
As shown in fig. 3, a schematic structural diagram of pile cap construction by using the CFG pile prefabricated pile cap hole-reserving grouting construction method according to the embodiment of the present disclosure is illustrated. Wherein, the periphery of the CFG pile 1 is undisturbed soil 4, the pile top of the CFG pile 1 is provided with a prefabricated pile cap 2, and the prefabricated pile cap 2 is provided with a grouting hole 201 and a groove 202. The grouting holes 201 and the grooves 202 are reserved on the precast pile caps 2, after the pile heads of the CFG piles 1 are chiseled and cleaned, the precast pile caps 2 are hung above the CFG piles 1, the grooves 202 reserved on the precast pile caps 2 are aligned with the pile heads of the CFG piles 1 and then are put down, the precast pile caps 2 are hoisted in place, then grouting materials 3 are grouted from the grouting holes 201 reserved on the precast pile caps 2, the grouting materials 3 adopt non-shrinkage grouting materials for grouting construction, the non-shrinkage grouting materials automatically level and fill gaps between the pile heads of the CFG piles 1 and the precast pile caps 2 and the grouting holes 201 reserved on the precast pile caps 2 (the reference number 3 in the drawing indicates the filled grouting materials) by means of self weight, so that the pile heads of the CFG piles 1 and the precast pile caps 2 can be integrally combined together to play a role in transferring foundation stress; the contact surface gap between the pile head of the CFG pile 1 and the prefabricated pile cap 2 and the reserved grouting hole 201 on the prefabricated pile cap 2 are filled by the self-leveling grouting material 3, so that the operation is simple, and the time and the labor are saved; the non-shrinkage grouting material has the characteristics of no shrinkage, early strength, self-fluidity, micro-expansion, quick hardening, self-compaction and the like, can ensure that the surface of the CFG pile precast pile cap after initial setting is smooth, the pile is compact and uniform, no bubble hole and the like are generated, and can ensure that the grouting material is firmly bonded with the precast pile cap and the pile head. After the hole-reserving grouting construction of the CFG pile precast pile cap is completed, roadbed filling 5 (such as A filling or B filling) is adopted to fill and level the periphery of the precast pile cap 2.
The non-shrinkage grouting material (CGM for short) is prepared by mixing and stirring 425# cement serving as a cementing material, a plurality of additives, a pure natural aggregate, quartz sand and the like, can be used after being stirred by adding water on site, and has the characteristics of no shrinkage, early strength, self-fluidity, micro-expansion, quick hardening, self-compaction and the like. According to the actual situation on site, a corresponding grouting mode is selected, and in general, "self-weight grouting" is adopted, namely, grouting materials are directly grouted from grouting holes reserved on the precast pile caps, and the grouting materials are completely self-leveled by self-weight and fill the whole grouting space.
Compared with a construction method of a CFG pile cast-in-place pile cap, the construction method of the CFG pile prefabricated pile cap hole reserving grouting can effectively solve a series of problems brought by the cast-in-place pile cap, the pile cap prefabrication is completed in a prefabrication factory, the CFG pile can be inserted in advance when being constructed, the construction period is not occupied, the pile cap prefabrication factory is synchronously performed, the prefabricated pile cap is only required to be hoisted in place and grouting construction operation is performed on site, favorable conditions can be created for the subsequent process to insert construction in advance, the construction period is short, and a large amount of labor can be saved; the construction quality can be ensured, the requirement of the construction period is ensured, the construction method has the characteristics of high construction speed, relatively simple process, easy quality control, low construction cost and the like, is favorable for environmental protection, and has great popularization value; the method is suitable for the construction of CFG pile cap composite structures in projects such as water conservancy projects, highway projects, house buildings, municipal projects and railways, and particularly has remarkable technical and economic benefits for projects with large project quantity, centralized tasks and short construction period of the CFG pile cap.
In some embodiments of the present disclosure, as shown in fig. 4 and 5, a plurality of grouting holes 201 are reserved on the precast pile cap 2, and when grouting construction work is performed in step five, grouting materials are sequentially poured from the plurality of grouting holes 201 according to a preset grouting sequence, and the grouting construction work is sequentially performed; wherein, one of the grouting holes is used as an exhaust hole in the grouting construction process, and after the other grouting holes are filled, the grouting hole used as the exhaust hole is filled with grouting material. By arranging a plurality of grouting holes and sequentially performing grouting construction operation according to a preset grouting sequence, grouting efficiency can be improved, and grouting uniformity can be improved; one of the grouting holes is used as an exhaust hole, so that on one hand, the gap between the pile head of the CFG pile and the contact surface of the prefabricated pile cap and the air in the grouting hole reserved on the prefabricated pile cap can be exhausted through the grouting hole, and on the other hand, whether grouting material is filled can be judged by observing whether grouting material overflows from the grouting hole.
In some embodiments of the present disclosure, as shown in fig. 5, five grouting holes 201 are reserved on the precast pile cap 2, where the five grouting holes 201 include a central grouting hole and four side grouting holes, the central grouting hole is disposed at a central portion of the precast pile cap 2, and the four side grouting holes are symmetrically disposed on two sides of the central grouting hole; when grouting construction operation is carried out in the fifth step, grouting construction operation is carried out in sequence according to the sequence of the edge grouting hole firstly and the center grouting hole secondly; the central grouting hole is used as an exhaust hole in the grouting construction process, and after the four side grouting holes are filled, the central grouting hole is filled with grouting materials. In concrete implementation, as shown in fig. 5, five grouting holes 201 can be numbered as 1#, 2#, 3#, 4#, and 5# in sequence, the grouting sequence of the precast pile cap can be 1# → 2# → 3# → 4# → 5#, the grouting construction operation is smoothly and sequentially performed, the grouting is uniformly and symmetrically performed from left to right, wherein the central 5# grouting hole serves as an exhaust hole, and after other grouting holes are filled, the 5# grouting hole is filled with grouting material.
In some embodiments of the present disclosure, the concrete grade of the prefabricated pile cap is preferably equal to the concrete strength grade of the pile body of the CFG pile, which is C20, and the prefabricated pile cap is constructed by using a prefabricated factory-shaped combined steel mold to ensure the concrete quality of the prefabricated pile cap. The precast pile cap 2 is preferably a precast circular plate pile cap, i.e. the shape of the precast pile cap 2 is preferably a circular plate. The diameter of a grouting hole 201 reserved on the precast pile cap 2 is 30mm, the grouting material 3 is non-shrinkage grouting material (CGM for short), and construction operation is performed by adopting self-weight grouting. The section of the groove 202 reserved on the prefabricated pile cap 2 is circular, the diameter of the groove is preferably 10 mm-20 mm larger than the diameter of the pile head of the CFG pile 1, namely the diameter of the groove 202 is larger than the diameter of the pile head of the CFG pile 1, and the difference value of the two is in the range of 10 mm-20 mm, so that the prefabricated pile cap 2 can be hoisted in place.
As shown in fig. 2, a schematic cross-sectional structure diagram of a CFG pile composite foundation is illustrated, and pile cap construction can be performed on the CFG pile composite foundation by using the CFG pile prefabricated pile cap hole-reserving grouting construction method provided by the embodiment of the present disclosure. This compound basis of CFG stake includes CFG stake 1 and mattress pad layer, and the pile bolck of CFG stake 1 is provided with prefabricated pile cap 2, and mattress pad layer is laid in prefabricated pile cap 2's top, and mattress pad layer includes two layers of geogrids 6 and the rubble bed course 7 that upwards sets gradually from down, and the top of rubble bed course 7 sets gradually embankment 8, bed bottom 9 and bed top layer gradation rubble 10 below the bed.
The following is a detailed description of the construction steps of the CFG pile precast pile cap hole-reserving grouting construction method according to the embodiment of the present disclosure.
Step one, excavating soil between piles
And after the CFG pile construction is finished and the strength meets the design requirement, excavating soil between piles. Specifically, a small excavator is used in cooperation with manual work to perform earth excavation. During excavation, firstly, the excavation width of the foundation is determined, temporary drainage ditches are excavated on two sides of the foundation, the side lines are excavated by using lime marks, and meanwhile, the excavation depth is determined by using a level gauge. During excavation, the excavator cannot damage the pile head of the CFG pile, and the phenomenon that the pile head is broken due to manual misoperation is strictly prohibited; excavating to a position 10cm above the pile top elevation of the CFG pile by using an excavator, and then cleaning to the pile top elevation of the CFG pile by adopting manual excavation; excavated earthwork needs to be cleared in time so as not to influence subsequent construction. After the pile is excavated to the elevation of the pile top, the foundation soil is tamped and leveled by a small tamping machine, so that the condition that the CFG pile cutting machine can cut the pile is achieved. After the pile is excavated to the designed elevation, the pile head above the designed pile top elevation is cut off by a handheld cutting tool, and the allowable deviation is controlled within +/-20 mm.
Step two, chiseling the pile head of the CFG pile
And after the excavation of the soil between the piles is finished, the pile head of the CFG pile is cut off. The constructor pops up the cutting position (higher than the designed elevation by 2cm) along the pile head by the ink line and cuts along the ink line position by the CFG pile cutting machine. Before cutting begins, a steel plate with the thickness of 100 multiplied by 0.4cm is cushioned under the CFG pile cutting machine, and the purpose of the steel plate is to enable the CFG pile cutting machine to walk smoothly and guarantee that the pile head pile top elevation deviation after cutting is within an allowable error range. Before pile cutting begins, ropes are tied to the two steel frame arms; when the pile is cut, one constructor holds the CFG pile cutting machine to be aligned with the position of the ink ejection line and slowly pushes forwards, the other constructor pulls the rope with proper force on the other side of the pile head, the pile head is cut along the direction to enable the depth of the joint cut of the two saw blades to be about 17cm, and then the same method is adopted for cutting by rotating a proper angle. After the pile head is knocked and brittle-broken manually, the pile head is directly loaded and transported out by adopting a wheel type small excavator.
Step three, prefabricating pile caps of CFG piles
The prefabricated pile cap template is made of a steel plate with the thickness of 2mm and the width of 600mm, the lap joint part is fixed by a screw rod for facilitating the form removal, and the diameter of the prefabricated pile cap template is consistent with that of the prefabricated pile cap. The prefabricated pile cap is constructed by adopting a shaping combined steel template in a prefabrication factory, then a steel mould is erected, 5 grouting holes with the diameter of 30mm are reserved in the middle, pile cap concrete is poured, a vibrating rod is used for vibrating, and air bubbles in the concrete are removed; after pouring, a groove with the diameter of 550mm and the thickness of 50mm is reserved on the pile cap, a foam plate or a prefabricated concrete circular plate is generally adopted, and the pile cap concrete is embedded before initial setting of the pile cap concrete to form the groove so as to facilitate the joint of the prefabricated pile cap and the pile head. In order to ensure that the prefabricated pile cap and the pile head of the CFG pile are installed in place, the diameter of the groove reserved on the prefabricated pile cap is 10-20 mm larger than the diameter of the pile head of the CFG pile. And after the pile cap shaping combined steel template is dismantled, cleaning the grouting holes reserved on the prefabricated pile cap. After cleaning, temporary plugging is carried out by using a plastic bag so as not to block the grouting hole, and the pile cap concrete is cured. After the strength of the pile cap concrete reaches the design requirement, hoisting and transporting can be carried out.
Step four, hoisting and positioning the prefabricated pile cap
And (4) transporting and positioning the prefabricated pile cap by a small excavator. Before the pile head is in place, the pile head surface of the CFG pile after chiseling is subjected to chiseling treatment, so that the pile head surface of the CFG pile is flat, then the pile head surface of the CFG pile is cleaned by clear water, and the pile head surface of the CFG pile is fully wet. When the precast pile cap is hoisted, the center of the precast pile cap is consistent with the center of the CFG pile body, if the deviation is too large, the precast pile cap may incline, further the foundation soil of the top plane of the precast pile cap irregularly deforms, the CFG pile is eccentrically pressed, the pile body of the CFG pile may be bent and broken, and the stability of the composite foundation is endangered. Therefore, the center of the prefabricated pile cap and the center of the CFG pile body meet the requirement of an allowable deviation range so as to ensure the effective transmission of the foundation stress load. Before the prefabricated pile cap is installed and constructed, paying-off and positioning are carried out, the pile position deviation must be rechecked in time, and the central position deviation of the CFG pile is strictly controlled. And after the prefabricated pile cap is installed in place, temporary reinforcement is carried out on the prefabricated pile cap.
Fifthly, grouting the prefabricated pile cap hole of the CFG pile
And after the prefabricated pile cap is hoisted in place, grouting construction operation is carried out by adopting grouting materials from grouting holes reserved on the prefabricated pile cap. Specifically, the non-shrinkage grouting material (CGM for short) is prepared by mixing and stirring 425# cement serving as a cementing material, a plurality of additives, pure natural aggregate, quartz sand and other materials, can be used after being stirred by adding water on site, and has the characteristics of no shrinkage, early strength, self-fluidity, micro-expansion, quick hardening, self-compaction and the like. According to the actual situation on site, a corresponding grouting mode is selected, and in general, "self-weight grouting" is adopted, namely, grouting materials are directly grouted from grouting holes reserved on the precast pile caps, and the grouting materials are completely self-leveled by self-weight and fill the whole grouting space. The water adding amount of the grouting material is determined according to the water-material ratio recommended by the product qualification certificate, drinking water is adopted as mixing water, the water temperature is preferably 5-40 ℃, and mechanical or manual stirring can be adopted. When mechanical stirring is adopted, the stirring time is generally 1-2 minutes; when manual stirring is adopted, 2/3 water is added firstly and stirred for 2 minutes, and then the rest water is added and stirred continuously until the mixture is uniform.
When grouting construction is carried out, grouting materials are required to be slowly and uniformly injected from grouting holes reserved in the prefabricated pile cap until the grouting materials flow out of the outer side edge of the prefabricated pile cap, and the grouting materials are guaranteed to be filled in the whole grouting holes and the gaps between the pile heads of the CFG piles and the prefabricated pile cap. After grouting is started, the grouting must be continuously carried out without interruption, and the grouting time should be shortened as much as possible. If the water seepage phenomenon on the surface of the precast pile cap is found in the grouting process, a small amount of CGM dry materials can be distributed and absorbed to dry; if the grouting material flows out from the outer side edge of the precast pile cap, the precast pile cap can be temporarily blocked by sand and compacted until the grouting material is not leaked.
Step six, checking grouting effect of CFG pile prefabricated pile cap
After the CFG pile prefabricated pile cap is grouted and initially set, the surface is ensured to be flat, compact and uniform, no bubble hole and the like are caused, and the grouting material is firmly bonded with the prefabricated pile cap and the pile head. The strength of the CFG pile precast pile cap in the next day after grouting can meet the design requirement, and the construction operation of the next procedure can be conveniently arranged as early as possible.
By adopting the CFG pile prefabricated pile cap hole reserving grouting construction method, a series of problems brought by the traditional cast-in-place pile cap can be effectively solved, the work of erecting, pouring, tamping, maintaining and the like of pile cap concrete can be completed in a prefabrication plant, the CFG pile can be inserted in advance when being constructed, the construction period is not occupied, and the construction is synchronously carried out in the prefabrication plant. On site, the prefabricated pile cap is hoisted in place by using a small excavator and grouting work is carried out, so that favorable conditions can be created for the subsequent next procedure to intervene in construction in advance, the construction period is short, and a large amount of labor can be saved.
Compared with the labor cost of the traditional cast-in-place concrete pile cap, the labor cost of a single pile cap can be reduced by about 50 percent; for the construction period of the CFG pile, about 90 days are needed by adopting a conventional cast-in-place mode, about 45 days are needed by adopting prefabricated pile cap hole-reserving grouting construction, and the construction period can be saved by 50 percent; the method has remarkable technical and economic benefits for projects with large project quantity, centralized tasks and short construction period of the CFG pile cap.
It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The foregoing are merely exemplary embodiments of the present disclosure, which enable those skilled in the art to understand or practice the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A CFG pile prefabricated pile cap hole reserving grouting construction method is characterized by comprising the following steps:
after the CFG pile is formed, excavating soil between piles;
after the excavation of the soil between the piles is finished, chiseling the pile heads of the CFG piles;
step three, prefabricating a pile cap of the CFG pile: the precast pile cap is formed by pouring concrete, and a grouting hole and a groove are reserved on the precast pile cap after pouring, wherein the groove is formed at one end part of the precast pile cap, and the grouting hole is communicated with the groove bottom wall of the groove;
hoisting the prefabricated pile cap above the CFG pile, putting down a groove reserved on the prefabricated pile cap after aligning with the pile head of the CFG pile, and installing the prefabricated pile cap in place;
and fifthly, after the prefabricated pile cap is installed in place, grouting material is poured into the prefabricated pile cap from a reserved grouting hole, the grouting material adopts non-shrinkage grouting material, and the non-shrinkage grouting material automatically levels and fills a gap between the pile head of the CFG pile and the prefabricated pile cap and the reserved grouting hole in the prefabricated pile cap by means of dead weight.
2. The CFG pile precast pile cap hole grouting construction method according to claim 1, wherein in the third step, a plurality of grouting holes are reserved on the precast pile cap;
and in the fifth step, grouting materials are sequentially injected from a plurality of grouting holes according to a preset grouting sequence, grouting construction operation is sequentially carried out, one grouting hole serves as an exhaust hole in the grouting construction process, and the grouting hole serving as the exhaust hole is filled with the grouting material after the other grouting holes are filled.
3. The CFG pile precast pile cap hole grouting construction method according to claim 2, wherein in the third step, five grouting holes are reserved on the precast pile cap, the five grouting holes comprise a central grouting hole and four side grouting holes, the central grouting hole is arranged at the central part of the precast pile cap, and the four side grouting holes are symmetrically arranged on two sides of the central grouting hole in pairs;
and in the fifth step, grouting construction operation is sequentially performed according to the sequence of the edge grouting holes firstly and the central grouting holes secondly, wherein the central grouting holes are used as exhaust holes in the grouting construction process, and after the four edge grouting holes are filled, the central grouting holes are filled with grouting materials.
4. The CFG pile precast pile cap hole grouting construction method of claim 1, wherein in the third step, the diameter of the grouting hole is 30 mm.
5. The CFG pile precast pile cap hole grouting construction method according to claim 1, wherein in the fifth step, during grouting construction operation, grouting material is slowly and uniformly poured into the grouting holes reserved in the precast pile cap until the grouting material flows out from the outer side edge of the precast pile cap, so that the grouting material is ensured to fill the whole grouting holes.
6. The CFG pile precast pile cap hole grouting construction method according to claim 5, wherein in the fifth step, if a water seepage phenomenon is found on the surface of the precast pile cap in the grouting construction process, a small amount of CGM dry material is distributed and the water is sucked; and if the grouting material flows out from the outer side edge of the precast pile cap, temporarily blocking and compacting the grouting material by using sand until the grouting material is not leaked.
7. The CFG pile precast pile cap hole grouting construction method according to claim 1, wherein in the third step, the section shape of the groove reserved on the precast pile cap is circular, the diameter of the groove is larger than that of the pile head of the CFG pile, and the difference value between the two is in the range of 10 mm-20 mm.
8. The CFG pile precast pile cap hole grouting construction method as claimed in any one of claims 1 to 7, wherein after the pile heads of the CFG piles are chiseled in the two pairs of steps, the pile head surface of the chiseled CFG pile is chiseled to make the pile head surface of the CFG pile flat.
9. The CFG pile precast pile cap hole grouting construction method as claimed in claim 8, wherein after the chiseling treatment is performed on the pile head surface of the CFG pile, the pile head surface of the CFG pile is cleaned with clean water, and the pile head surface of the CFG pile is ensured to be sufficiently wet.
10. The CFG pile precast pile cap hole reserving grouting construction method as claimed in any one of claims 1 to 7, wherein when the pile-to-pile soil excavation is performed in the first step, firstly, an excavator is adopted to excavate to 10cm above the pile top elevation of the CFG pile, then, manual excavation is adopted to clear up to the pile top elevation of the CFG pile, and then, a tamping machine is adopted to tamp and level the foundation soil, so as to achieve the condition of using a CFG pile cutting machine to cut the pile.
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