CFG pile construction method

Abstract

The invention discloses a CFG pile construction method. The method comprises the following steps that S10, a CFG pile construction site is leveled; s20, drilling is conducted according to the preset CFG pile position coordinates, and a pile hole is formed; s30, concrete is poured into the pile hole to the elevation position of the pile top of the CFG pile; s40, after pouring is completed, concrete at the pile top elevation position of the CFG pile is cleaned according to a preset range before initial setting of the concrete; s50, the pile top of the CFG pile is poured to the elevation position of the pile top of the CFG pile again; and S60, the construction site is leveled, a shaping cap steel formwork is installed at the pile top position, and the shaping cap steel formwork is integrally formed. Therefore, construction efficiency can be improved, construction cost can be reduced, waste of equipment resources can be reduced, and construction quality can be ensured.

Description

Technical Field

[0001] The invention relates to the technical field of CFG pile foundation construction, and in particular to a CFG pile construction method. Background Art

[0002] CFG pile is the abbreviation of Cement Fly-ash Gravel, which means cement fly ash gravel pile. It is a variable strength pile made by mixing crushed stone, stone chips, sand, fly ash, cement and water with various pile-making machines. It is widely used because of its advantages such as high foundation bearing capacity, small settlement deformation and low cost.

[0003] In the current CFG pile construction technology, the pile cap construction starts after the pile body construction is completed and the pile head is cut. The specific methods include: the CFG pile construction starts after the construction site is leveled, and the soil between the piles is excavated by a small excavator after the CFG pile construction is completed; after the soil excavation between the piles is completed, the pile head is cut according to the designed elevation of the pile top; after the pile head is cut, the soil between the piles is leveled and rolled, and after that, the pile cap steel bars are installed on the pile top; after the pile cap steel bars are completed, the pile cap formwork is installed; after the pile cap formwork is installed, the pile cap concrete is poured, and the pile cap formwork is removed after the concrete reaches the strength; after the pile cap formwork is removed, the graded gravel between the pile caps is filled, and a small roller is used for rolling during the filling process; after the graded gravel between the pile caps is filled, the cushion layer is filled.

[0004] However, the existing technology has the following disadvantages: when excavating the soil between piles, a large amount of soil needs to be dug out and transported out, which has low construction efficiency and wastes equipment resources; during the excavation of the soil between piles, the excavator can easily cause damage to the pile body, affecting the construction quality; after the excavation of the soil between piles is completed, the pile head needs to be cut by a cutting machine, which wastes the pile head concrete; the process of cutting the pile head is time-consuming and labor-intensive, affecting the construction progress; the pile cap formwork is generally assembled by four plastic steel formworks, and the installation process is time-consuming and labor-intensive, and the formwork is easily damaged during use; during the graded gravel filling between the pile caps, the roller can easily press the pile cap concrete to the side and drop the corners, affecting the quality of the project. Summary of the invention

[0005] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0006] To this end, an object of the present invention is to provide a CFG pile construction method that can improve construction efficiency, reduce construction costs, reduce resource waste, and ensure construction quality.

[0007] To achieve the above object, the present invention proposes a CFG pile construction method, comprising the following steps:

[0008] S10, leveling the CFG pile construction site;

[0009] S20, drilling according to the preset CFG pile position coordinates to form a pile hole;

[0010] S30, pouring concrete into the pile hole to the top elevation of the CFG pile;

[0011] S40, after the pouring is completed, before the concrete has initially set, the concrete at the top elevation of the CFG pile is cleaned according to a preset range;

[0012] S50, re-casting the top of the CFG pile to the top elevation of the CFG pile;

[0013] S60, leveling the construction site and installing a forming cap steel formwork at the pile top, wherein the forming cap steel formwork is integrally formed.

[0014] In addition, the CFG pile construction method proposed in the application may also have the following additional technical features:

[0015] Specifically, the shaping cap rigid template includes a top plate, a plurality of side plates and a U-shaped baffle plate, wherein two connected side plates are connected to each other, and the side plates are fixed between the top plate and the baffle plate; the side plates, the top plate and the baffle plate are integrally formed.

[0016] Specifically, the top plate and the baffle are coaxially arranged, and the projection area of ​​the baffle is smaller than the projection area of ​​the top plate, and the side plate is inclined from the direction of the top plate to the direction of the baffle.

[0017] Specifically, step S10 also includes controlling the site elevation to be consistent with the CFG pile top elevation.

[0018] Specifically, in step S40, the preset range is 10-20 cm downward from the elevation position of the top of the CFG pile.

[0019] Specifically, step S50 also includes step S500 and step S501, wherein, in step S500, before re-casting the top of the CFG pile, a circular plastic formwork is installed at the elevation position; in step S501, the plastic formwork is cast to the elevation of the top of the CFG pile, and the plastic formwork is removed after the strength of the cast concrete reaches a first preset strength.

[0020] Specifically, the diameter of the plastic formwork is the same as the diameter of the CFG pile.

[0021] Specifically, the method further includes the following steps: S70, backfilling graded crushed stone between the shaping cap steel formwork and the shaping cap steel formwork, and performing compaction;

[0022] S80, after the graded crushed stone strength reaches the second preset strength, the shaping cap steel template is taken out, and a grid groove is formed in the foundation;

[0023] S90, installing pile cap reinforcement in the square groove, and pouring the square groove after the pile cap reinforcement is installed;

[0024] S100, after the casting of the plurality of square troughs is completed, the lowering reaches a third preset strength, and then the roadbed cushion layer is laid.

[0025] Specifically, step S90 also includes S900, wherein, in S900, the concrete is vibrated and compacted during the pouring process.

[0026] Specifically, the backfill graded crushed stone includes 1% cement.

[0027] The technical solution provided by the embodiment of the present invention has the following advantages compared with the prior art:

[0028] (1) The present application reduces the process of excavating and transporting soil between piles by drilling holes and controlling the concrete pouring elevation of CFG piles in advance, and also avoids damage to the pile body caused by the excavator during the excavation process. There is no need to cut the pile head, which speeds up the construction speed. At the same time, it saves the amount of concrete used in the cut pile head, reduces resource waste, and ensures construction quality.

[0029] (2) By using the fixed pile cap rigid formwork to implement the post-installation method of the pile cap, it is possible to avoid the roller pressing the pile cap concrete off-center and cornering during the graded gravel filling between the pile caps, which affects the quality of the project. At the same time, it reduces the installation time of the pile cap formwork and reduces the damage of the pile cap formwork during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0032] Figure 1 is a flow chart of a CFG pile construction method according to one embodiment of the present invention;

[0033] Figure 2 It is a schematic structural diagram of a shaping cap rigid template according to an embodiment of the present invention.

[0034] As shown in the figure: 10, the molding cap steel template; 101, the top plate; 102, the side plate; 103, the baffle; 104, the handle; 105, the anti-slip baffle. DETAILED DESCRIPTION

[0035] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0036] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0037] The CFG pile construction method according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0038] like Figure 1 As shown, the CFG pile construction method of the embodiment of the present invention may include the following steps:

[0039] Step 1: Level the CFG pile construction site, where leveling the construction site includes clearing obstacles, surface rolling and drainage measures.

[0040] Among them, clearing obstacles means clearing the original surface vegetation, tree roots and other obstacles within the site. At the same time, investigate and clear underground pipelines (such as water, electricity, oil, communications, etc.) and underground obstacles (such as large stones, huge construction waste, etc.) to ensure that there are no obstacles on the construction site.

[0041] Surface compaction: After clearing obstacles, use a roller to compact the site to meet the requirements of resisting drilling rig tipping.

[0042] Drainage measures: temporary drainage ditches should be built on both sides of the roadbed to ensure smooth drainage without water accumulation. When the soil on the site is soft, appropriate cushion layers can be laid or compacted on the spot to increase the bearing capacity of the foundation and facilitate the movement of construction machinery and material transport vehicles.

[0043] Furthermore, step 1 also includes controlling the site elevation to be consistent with the CFG pile top elevation. The purpose of this design is to simplify the subsequent CFG pile pouring work. Because once the site elevation is aligned with the pile top elevation, the construction personnel can directly determine the pouring depth of the CFG pile based on the site elevation, thereby ensuring that the pile length meets the design requirements, avoiding the situation where the site elevation is lower than the pile top elevation, resulting in the actual pile length of the CFG pile being insufficient to support the structure, affecting the structural safety, or avoiding the situation where if the site elevation is higher than the pile top elevation, additional soil removal between the piles may be required in subsequent construction to reach the pile top elevation, increasing the workload and reducing the construction efficiency. The site elevation can be determined based on the CFG pile top elevation.

[0044] Step 2: Drilling is performed according to the preset CFG pile position coordinates to form pile holes, wherein the preset CFG pile position coordinates can be determined by technicians according to the design drawings to place the specific position of each CFG pile and mark it.

[0045] Specifically, a marker (such as a bamboo chopstick or a steel bar head) can be manually driven into the ground at the center of the pile position, and a circle can be drawn with lime according to the pile diameter with the engineering pile position as the center. Then, a spiral drill can be used to drill holes according to the CFG pile position coordinates.

[0046] It should be noted that the position needs to be corrected during drilling so that the drill rod is vertically aligned with the center of the pile. The offset between the drill tip and the pile point needs to be controlled within a certain range (e.g., no more than 50 mm) to ensure that the verticality tolerance of the CFG pile is no more than 1%. At the same time, the verticality of the drill rod can also be controlled by hanging a plumb bob on the drill frame or using the verticality adjuster that comes with the drilling rig.

[0047] Step 3, pour concrete into the pile hole to the top elevation of the CFG pile, where the top elevation of the CFG pile can be determined based on the design drawings and the rock penetration depth on site. Generally, in the design process of the pile, the top elevation of the pile is first determined by the foundation elevation of the building, and then the pile length is calculated based on the bearing capacity. The pile bottom elevation can be determined by the pile top elevation and the pile length, that is, the pile bottom elevation = pile top elevation - pile length.

[0048] It should be noted that when pouring concrete into the pile hole, it is necessary to ensure that the concrete is poured into the pile hole evenly and continuously until the top elevation of the CFG pile is reached and the pouring is stopped.

[0049] Step 4: After pouring is completed, before the concrete has initially set, clean the concrete at the top elevation of the CFG pile within a preset range.

[0050] It should be noted that during the concrete pouring process, due to factors such as vibration and water seepage, a layer of slurry may form on the concrete surface at the top elevation of the pile, and some impurities may be mixed in. The presence of this layer of slurry and impurities will affect the strength and durability of the concrete. Therefore, cleaning can remove these uneven or loose parts to ensure the quality of the concrete on the top of the pile. Cleaning before the concrete has initially set is not only convenient for operation, saving time and effort, but also avoids chiseling when the concrete strength has not yet formed or has not reached a certain strength, which will disturb the concrete, destroy the concrete strength, or cause small cracks inside the concrete.

[0051] Furthermore, the preset range in step 4 is 10-20 cm downward from the top elevation of the CFG pile. This preset range is determined based on actual construction experience and the performance characteristics of concrete, which can ensure that the cleaning effect is optimal while not removing too much concrete, thereby reducing material waste and avoiding unnecessary damage to the pile body. Among them, cleaning downward 10-20 cm until a clean, fresh concrete pile body is exposed can ensure the bearing capacity of the pile end and avoid affecting the bearing capacity of the pile end due to a thick mixed layer of concrete and mud. For example, 10 cm, 11 cm, 15 cm, etc. can be cleaned downward according to actual conditions.

[0052] Step 5: Re-pour the top of the CFG pile to the top elevation of the CFG pile. By re-pouring, it can be ensured that the concrete on the top of the pile reaches the design strength and quality, which can reduce the subsequent maintenance and repair costs caused by quality problems on the top of the pile. The re-poured concrete can fill the gaps left after cleaning and improve the density and uniformity of the concrete on the top of the pile, which helps to enhance the overall strength, stability and bearing capacity of the pile.

[0053] Furthermore, step 5 also includes installing a circular plastic formwork at the elevation position before re-pouring the top of the CFG pile, wherein by installing the circular plastic formwork, it can be ensured that the pile top forms the expected circular shape and size during the pouring process to meet the design requirements, and the plastic formwork has the characteristics of smooth surface and low moisture absorption, which helps to reduce the water loss and bubble generation of concrete during the pouring process, thereby improving the quality and density of the concrete on the pile top, and by pouring concrete in the plastic formwork, the density and uniformity of the concrete on the pile top can be ensured, thereby ensuring the strength and durability of the concrete.

[0054] Furthermore, step 5 also includes pouring the plastic formwork to the CFG pile top elevation, and removing the plastic formwork after the poured concrete strength reaches a first preset strength. The plastic formwork is light, easy to install and remove, which simplifies the construction operation and improves the construction efficiency. The first preset strength can be determined according to design requirements or actual conditions. The strength test of the poured concrete can be carried out by a rebound method, a core drilling method, an ultrasonic method, etc.

[0055] Exemplarily, taking the rebound method as an example, the rebound value of the surface hardness of concrete is measured by a rebound tester, and the compressive strength of concrete is indirectly estimated based on the pre-established empirical relationship between the rebound value and the concrete strength.

[0056] Furthermore, the diameter of the plastic formwork is the same as the diameter of the CFG pile. Using the plastic formwork with the same diameter as the CFG pile can ensure that the top of the recast CFG pile has the correct shape and size and meets the design requirements, thereby ensuring the uniformity and integrity of the pile top.

[0057] Step 6, leveling the construction site and installing the shaping cap steel template 10 at the pile top position, wherein the shaping cap steel template 10 is integrally formed.

[0058] Specifically, after removing the plastic formwork, the construction site is leveled. A level construction site can provide an accurate reference surface for subsequent construction, which is crucial for subsequent construction steps such as installing the shaped cap steel formwork 10. The leveling of the site helps to ensure the accurate position of the shaped cap steel formwork 10, thereby ensuring that the geometric size and position of the entire structure meet the design requirements. At the same time, a level construction site can reduce the adjustment work in subsequent construction and improve construction efficiency. For example, a level site can simplify the installation process of the shaped cap steel formwork and reduce the time wasted due to uneven ground.

[0059] Secondly, compared with the template composed of four plastic steel templates assembled in the prior art, the one-piece design of the shaping cap steel template 10 can ensure that the shape and size of the pile cap concrete are more accurate, avoiding the problems of loose joints and dimensional deviations that may occur in the assembled templates, thereby improving the quality of concrete molding. At the same time, due to the integrity of the shaping cap steel template 10, the risk of the roller pressing the pile cap concrete to the side or dropping the corners during the graded gravel filling process can be reduced, protecting the structural integrity of the pile cap, thereby improving the project quality. The one-piece shaping cap steel template 10 reduces the time for template installation and disassembly, can significantly reduce the time for pile cap template installation, and improve construction efficiency.

[0060] In one embodiment of the present invention, Figure 2 As shown, the shaping cap rigid plate 10 comprises a top plate 101, a plurality of side plates 102 and a baffle plate 103 in a square shape.

[0061] Among them, the two connected side plates 102 are connected to each other, and the side plates 102 are fixed between the top plate 101 and the baffle plate 103. The side plates 102, the top plate 101 and the baffle plate 103 are formed in one piece, that is, by setting the baffle plate 103 in a mouth shape, the contact area with the foundation can be increased, thereby preventing the shaping cap rigid template 10 from being pressed into the soil during the rolling process of the roller.

[0062] Furthermore, if Figure 2 As shown, the top plate 101 and the baffle plate 103 are arranged coaxially, and the projected area of ​​the baffle plate 103 is smaller than the projected area of ​​the top plate 101, and the side plate 102 is inclined from the direction of the top plate 101 to the direction of the baffle plate 103. The above arrangement enables the shaping cap rigid template 10 to form a structure that is wide at the top and narrow at the bottom, which can be beneficial to the subsequent backfilling and removal of graded gravel between piles.

[0063] As a possible scenario, Figure 2As shown, the molding cap steel template 10 also includes a handle 104 and an anti-detachment baffle 105, wherein the handle 104 is arranged on the top plate 101, and the anti-detachment baffle 105 is arranged inside the molding cap steel template 10. The design of the handle 104 can facilitate the installation and disassembly of the molding cap steel template 10, and the design of the anti-detachment baffle 105 can prevent the handle 104 from falling off.

[0064] In one embodiment of the present invention, Figure 1 As shown, the CFG pile construction method of the embodiment of the present invention also includes the following steps:

[0065] Step 7, backfill graded crushed stone between the shaping cap steel formwork 10 and the shaping cap steel formwork 10, and compact them. The graded crushed stone can fill the gap between the shaping cap steel formwork 10 and the shaping cap steel formwork 10, thereby enhancing the tightness and stability of the overall structure. By compacting with a small roller, it can be ensured that the backfill material meets the specified density and strength requirements, which helps to reduce foundation settlement and deformation and ensure the long-term stability and safety of the building.

[0066] Furthermore, the backfill graded crushed stone includes 1% cement. After adding 1% cement, the graded crushed stone can form a more solid structure under the action of cement, and the gelling effect of cement enables the crushed stone particles to be better bonded together, thereby improving the strength and durability of the overall structure.

[0067] Step 8, after the graded crushed stone strength reaches the second preset strength, remove the shaping cap steel template 10, and a grid groove is formed in the foundation. The second preset strength can be tested by rebound method, core drilling method, ultrasonic method, etc. The second preset strength can be set according to design requirements or actual conditions.

[0068] Step 9, installing pile cap reinforcement in the square groove, and pouring the square groove after the pile cap reinforcement is installed, wherein step 9 also includes vibrating the concrete to make it dense during the pouring process, and vibrating and compacting can eliminate bubbles and holes in the concrete, improve the density and strength of the concrete, and the dense concrete can better combine with the reinforcement to form a more solid structure, and the vibration can be carried out with a vibrating rod.

[0069] Step 10, after the strength of multiple grid grooves is cast, reaches the third preset strength, then the roadbed cushion layer is laid. The third preset strength can be tested by rebound method, core drilling method, ultrasonic method, etc. The third preset strength can be set according to design requirements or actual conditions.

[0070] Specifically, compared with traditional construction methods, the present application reduces the process of excavating and transporting soil between piles by drilling holes and controlling the concrete pouring elevation of CFG piles in advance, and also avoids damage to the pile body caused by the excavator during the excavation process. There is no need to cut the pile head, which speeds up the construction speed. At the same time, it saves the amount of concrete used in the cut pile head, reduces resource waste, and ensures construction quality.

[0071] At the same time, by using the fixed pile cap rigid formwork to implement the post-placement method of the pile cap, it is possible to avoid the roller pressing the pile cap concrete off-center and dropping the corners during the graded gravel filling between the pile caps, thereby affecting the quality of the project. At the same time, it reduces the installation time of the pile cap formwork and reduces the damage of the pile cap formwork during use.

[0072] In summary, the CFG pile construction method of the embodiment of the present application can improve construction efficiency, reduce construction costs, reduce resource waste, and ensure construction quality.

[0073] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0074] The above description is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments described herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A CFG pile construction method, characterized in that: The steps include: S10, leveling the CFG pile construction site; S20, drilling according to the preset CFG pile position coordinates to form a pile hole; S30, pouring concrete into the pile hole to the top elevation of the CFG pile; S40, after the pouring is completed, before the concrete has initially set, the concrete at the top elevation of the CFG pile is cleaned according to a preset range; S50, re-casting the top of the CFG pile to the top elevation of the CFG pile; S60, leveling the construction site and installing a forming cap steel formwork at the pile top, wherein the forming cap steel formwork is integrally formed.

2. The CFG pile construction method according to claim 1, characterized in that: The shaping cap steel plate comprises a top plate, a plurality of side plates and a baffle plate in a square shape, wherein: The two side plates are connected to each other, and the side plates are fixed between the top plate and the baffle plate; The side plate, the top plate and the baffle are integrally formed.

3. The CFG pile construction method according to claim 2, characterized in that: The top plate and the baffle are coaxially arranged, and the projection area of ​​the baffle is smaller than the projection area of ​​the top plate. The side plate is inclined from the direction of the top plate to the direction of the baffle.

4. The CFG pile construction method according to claim 1, characterized in that: Step S10 also includes controlling the site elevation to be consistent with the CFG pile top elevation.

5. The CFG pile construction method according to claim 1, characterized in that: In step S40, the preset range is 10-20 cm downward from the elevation position of the top of the CFG pile.

6. The CFG pile construction method according to claim 1, characterized in that: Step S50 also includes step S500 and step S501, wherein: Step S500, before re-casting the top of the CFG pile, install a circular plastic template at the elevation position; Step S501, pouring concrete into the plastic formwork to the CFG pile top elevation, and removing the plastic formwork after the poured concrete strength reaches a first preset strength.

7. The CFG pile construction method according to claim 6, characterized in that: The diameter of the plastic formwork is the same as the diameter of the CFG pile.

8. The CFG pile construction method according to claim 1, characterized in that: The following steps are also included: S70, backfilling graded crushed stone between the shaping cap steel formwork and the shaping cap steel formwork, and performing compaction; S80, after the graded crushed stone strength reaches the second preset strength, the shaping cap steel template is taken out, and a grid groove is formed in the foundation; S90, installing pile cap reinforcement in the square groove, and pouring the square groove after the pile cap reinforcement is installed; S100, after the casting of the plurality of square troughs is completed, the lowering reaches a third preset strength, and then the roadbed cushion layer is laid.

9. The CFG pile construction method according to claim 8, characterized in that: The step S90 also includes S900, wherein: S900, vibrate and compact the concrete during pouring.

10. The CFG pile construction method according to claim 8, characterized in that: The backfill graded crushed stone includes 1% cement.

Images