CN115233668A - Post-grouting construction method for precast tubular pile by internally hammering pile tip into rock - Google Patents
Post-grouting construction method for precast tubular pile by internally hammering pile tip into rock Download PDFInfo
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- CN115233668A CN115233668A CN202210981228.8A CN202210981228A CN115233668A CN 115233668 A CN115233668 A CN 115233668A CN 202210981228 A CN202210981228 A CN 202210981228A CN 115233668 A CN115233668 A CN 115233668A
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- 239000011435 rock Substances 0.000 title claims abstract description 77
- 238000010276 construction Methods 0.000 title claims abstract description 44
- 238000000034 method Methods 0.000 claims abstract description 39
- 230000009471 action Effects 0.000 claims abstract description 18
- 230000008569 process Effects 0.000 claims abstract description 18
- 239000002689 soil Substances 0.000 claims abstract description 13
- 229910000831 Steel Inorganic materials 0.000 claims description 43
- 239000010959 steel Substances 0.000 claims description 43
- 239000002002 slurry Substances 0.000 claims description 30
- 230000003068 static effect Effects 0.000 claims description 9
- 239000012466 permeate Substances 0.000 claims description 8
- 239000000463 material Substances 0.000 claims description 7
- 230000005484 gravity Effects 0.000 claims description 5
- 239000011150 reinforced concrete Substances 0.000 claims description 5
- 238000013459 approach Methods 0.000 claims description 4
- 238000013461 design Methods 0.000 claims description 4
- 238000003780 insertion Methods 0.000 claims description 3
- 230000037431 insertion Effects 0.000 claims description 3
- 230000035515 penetration Effects 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 3
- 238000004062 sedimentation Methods 0.000 claims description 3
- 238000003466 welding Methods 0.000 claims description 2
- 238000000926 separation method Methods 0.000 claims 1
- 230000006378 damage Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- 238000007569 slipcasting Methods 0.000 description 3
- 230000001360 synchronised effect Effects 0.000 description 3
- 230000007547 defect Effects 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 238000005553 drilling Methods 0.000 description 2
- 230000001050 lubricating effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 210000000078 claw Anatomy 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000011440 grout Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
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Classifications
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D7/00—Methods or apparatus for placing sheet pile bulkheads, piles, mouldpipes, or other moulds
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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
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/24—Prefabricated piles
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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
- E02D5/72—Pile shoes
Abstract
The invention discloses a post-grouting construction method for a precast tubular pile, which realizes the purpose that a pile tip enters a rock through internal hammering. The method adopts a novel movable pile shoe which extends into the bottom of the precast tubular pile in a non-fixed form for assembly, so that impact force can be independently applied to the movable pile shoe and the movable pile shoe is impacted to downwards enter a rock stratum, and the pile body of the precast tubular pile cannot synchronously sink along with the pile shoe under the action of soil around the pile, thereby reducing the compressive stress of the pile body after entering a bearing stratum and ensuring the integrity of the pile body in a bedrock driving process. The pile can enter a bearing stratum during piling, so that the rock-entering depth of the prefabricated pipe pile is effectively increased, and after the pile tip enters the bearing stratum, the pile tip is separated from gaps on two sides of the pipe pile to fill rock debris with higher strength of the bearing stratum, so that the uplift bearing capacity of the pile foundation is further improved. Meanwhile, the post-grouting operation of the invention enables the pile shoe to be connected with the inner wall of the tubular pile, thereby playing the role of fixing the movable pile shoe and increasing the stability of the pile foundation.
Description
Technical Field
The invention belongs to the field of construction equipment, and particularly relates to a precast tubular pile post-grouting construction method for realizing the purpose that a pile tip enters rock through internal hammering.
Background
The prestressed pipe pile has the advantages of high pile bearing capacity, high construction speed, small environmental pollution, reasonable cost control, easy length adjustment, relatively reliable quality, convenient monitoring, low price of a single pile, wide application range, short construction period and the like. In recent years, the method is widely applied to the field of building engineering, and is particularly suitable for engineering in areas with deep soft soil and thick silt.
At present, the difficulty of entering a soil layer of the existing prestressed pipe pile is often reduced by fixing a pile shoe at the bottom of the existing prestressed pipe pile, and meanwhile, a lubricating auxiliary measure can be introduced into partial technology. For example, in an invention patent with the application number of CN201810132421.8, a synchronous grouting prestressed pipe pile and a construction method thereof are disclosed, which comprises a special pile shoe device, a prefabricated pipe pile, a grouting pipe device and a grouting layer; the special pile shoe device comprises a main grouting pipe, a branch pipe joint, branch pipes and a grout outlet; the upper end of the main grouting pipe is connected with the grouting pipe device, and the lower end of the main grouting pipe is connected with branch pipes through branch pipe joints; the branch pipes are connected with slurry outlet holes, and the slurry outlet holes are distributed on the outer side of the pipe pile seam at the edge of the pile shoe at equal intervals; be equipped with slip casting pipe device in the precast tubular pile cavity, slip casting pipe device includes four claw couples, upper end interface, slip casting pipeline and lower extreme interface. According to the scheme, the special pile shoe is additionally arranged on the prestressed pipe pile, and grouting liquid is used for lubricating the side wall of the pipe pile through synchronous grouting, so that the pile sinking difficulty of the static pressure method is reduced.
However, such an approach may be used to facilitate driving of the pre-stressed pipe pile into the earth, but in engineering practice, where the pile foundation is driven into the rock, the depth of the prefabricated pile driven into the rock using conventional pile shoes is at most highly weathered, and the effect of the lubrication measures on the rock formation is not great. Furthermore, when the pile enters the supporting layer, the compressive stress of the pile body increases rapidly, and the stronger the rigidity of the supporting layer, the greater the compressive stress applied to the pile body, and the joint of two piles may be damaged seriously by the repeated action of compressive and tensile stress.
Therefore, how to solve the defect that the pile body structure is easy to damage in the process of driving the precast tubular pile into the holding force rock stratum in the construction process is a technical problem to be solved urgently at present.
Disclosure of Invention
The invention aims to solve the defect that a pile body structure is easy to damage in the process of driving a precast tubular pile into a bearing rock stratum in the prior art, and provides a post-grouting construction method of the precast tubular pile, which realizes the purpose that a pile tip enters the rock through internal hammering.
The invention adopts the following specific technical scheme:
a post-grouting construction method for a precast tubular pile by internally hammering the pile tip into rock comprises the following steps:
s1, placing a prefabricated movable pile shoe on the surface of a foundation, wherein the movable pile shoe comprises a first cylindrical section, a second cylindrical section and a cross conical pile tip; the first cylindrical section, the second cylindrical section and the cross conical pile tip are coaxially connected and fixed from top to bottom; the diameter of the first cylindrical section is smaller than the inner diameter of the precast tubular pile, the diameter of the second cylindrical section is the same as the outer diameter of the precast tubular pile, the top surface of the second cylindrical section serves as a pile end supporting surface, and a plurality of radial grouting channels are formed in the top surface of the second cylindrical section;
s2, vertically hoisting the precast tubular pile, aligning the precast tubular pile with a movable pile shoe, then putting the precast tubular pile downwards, enabling a first cylindrical section of the movable pile shoe to extend into the bottom of an inner cavity of the precast tubular pile, maintaining an annular gap between the first cylindrical section and the movable pile shoe, enabling grouting slurry to permeate into the annular gap, supporting a bottom pile end of the precast tubular pile on the top surface of a second cylindrical section, and enabling the tip of a cross conical pile tip to be vertically downwards, so that a precast tubular pile structure with a pile shoe is assembled;
s3, applying sinking pressure to the top of the precast tubular pile by a hammering method or a static pressure method, sinking the precast tubular pile structure with the pile shoe into the foundation as a whole, and stopping applying the sinking pressure to the top of the precast tubular pile until the movable pile shoe approaches or partially enters a rock stratum;
s4, suspending the impact hammer in the air and at the top of the inner cavity of the precast tubular pile, controlling a lifting rope to release the impact hammer to enable the impact hammer to freely fall along the inner cavity of the precast tubular pile under the action of gravity and to be hammered on the top surface of the first cylindrical section of the movable pile shoe, drilling the movable pile shoe into a rock stratum under the action of impact force, enabling the precast tubular pile not to synchronously sink along with the movable pile shoe under the action of side friction resistance of a soil layer around the pile, and enabling a settlement height difference to occur between the movable pile shoe and the precast tubular pile;
s5, continuously repeating the step S4 until the movable pile shoe is sunk into a bearing layer with a specified depth in a rock stratum, and finally enabling the top surface of the second cylindrical section of the movable pile shoe to be separated from the bottom pile end of the prefabricated pipe pile through the accumulated sedimentation height difference between the prefabricated pipe pile and the movable pile shoe, wherein the first cylindrical section still partially extends into the inner cavity of the prefabricated pipe pile, and the bottom end surface of the prefabricated pipe pile, the top surface of the second cylindrical section and the outer side surface of the first cylindrical section jointly form an annular groove space with an outward opening; the space of the annular groove is filled with crushed rocks generated in the process of inserting the pile tip into the rocks;
s6, extending a grouting guide pipe into the prefabricated pipe pile from the top of the inner cavity of the prefabricated pipe pile, grouting the prefabricated pipe pile, accumulating grouting slurry at the top of the first cylindrical section, continuously permeating into the annular gap and filling the annular gap and the gap of crushed rocks in the annular groove space, and finally stopping grouting after a section of slurry column with stable height is formed at the top of the first cylindrical section; and after the grouting slurry in the precast tubular pile is cured, finishing post grouting construction of the precast tubular pile.
Preferably, before prefabricating the movable pile shoe, the height of the first cylindrical section needs to be designed according to the depth of the movable pile shoe which should be sunk into a rock stratum, so that the first cylindrical section is still partially positioned in the prefabricated pipe pile after the movable pile shoe is sunk to the specified depth, and the movable pile shoe and the prefabricated pipe pile are prevented from being completely separated.
Preferably, the lifting rope connected to the impact hammer is controlled by an external lifting device.
Preferably, the cross conical pile tip comprises an end plate and a cross pile tip arranged on the end plate, and the end plate is attached and fixed to the bottom surface of the second cylindrical section;
preferably, in the cross-shaped conical pile tip, the cross-shaped pile tip is formed by welding three triangular steel plates on a round end plate made of steel; one of the right-angled triangular steel plates is an isosceles triangular steel plate, the bottom edge of the right-angled triangular steel plate is arranged along the diameter of the end plate and welded and fixed, the other two right-angled triangular steel plates are respectively and vertically arranged on two sides of the isosceles triangular steel plate, one right-angled edge of each right-angled triangular steel plate is arranged along the radius of the circular end plate and welded and fixed, and the other straight edge of each right-angled triangular steel plate is welded and fixed with the side face of the isosceles triangular steel plate.
Preferably, the material of the first cylindrical section and the second cylindrical section is steel or reinforced concrete material.
Preferably, the grouting channel radially penetrates through the annular top surface of the second cylindrical section.
Preferably, a plurality of grouting channels are uniformly arranged on the annular top surface of the second cylindrical section along the circumferential direction.
Preferably, the lifting rope is a steel rope.
Preferably, in the construction preparation stage, the surface of the foundation is subjected to paying-off positioning in advance according to the design requirements of the pile foundation, and the post-grouting construction method of the precast tubular pile is respectively executed on the positioning point of each pile.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a post-grouting construction method of a precast tubular pile, which realizes the insertion of a pile tip into rock through internal hammering, and the method is characterized in that a movable pile shoe extends into the bottom of the precast tubular pile in a non-fixed mode to be assembled, so that impact force can be independently acted on the movable pile shoe to impact the movable pile shoe downwards into a rock stratum in the pile sinking process, and a pile body of the precast tubular pile cannot synchronously sink along with the pile shoe under the action of soil around the pile, thereby reducing the compressive stress of the pile body after entering a bearing stratum and ensuring the integrity of the pile body in the process of driving the pile body into a bedrock.
The technical scheme in the subsequent embodiment of the invention has one or more of the following advantages:
1. the large-rigidity movable pile shoe can effectively increase the rock penetration depth of the prefabricated pipe pile to the stroke bedrock during pile driving, and improves the bearing capacity of the pile end.
2. After the pile tip enters the bearing layer, the pile tip is separated from gaps on two sides of the tubular pile to fill rock debris with high strength of the bearing layer, and the uplift bearing capacity of a pile foundation can be improved.
3. When the precast pile enters the bearing stratum, the compressive stress of the pile body after entering the bearing stratum can be reduced, the integrity of the pile body is ensured, and the precast pile is further ensured to be smoothly driven into bedrock.
4. The post-grouting operation of the invention enables the pile shoe to be connected with the inner wall of the tubular pile, and also plays a role in fixing the movable pile shoe, thereby increasing the stability of the pile foundation.
5. The construction device and the construction method are simple and convenient to operate and convenient for practical engineering application.
Drawings
Fig. 1 is a flow diagram of a precast tubular pile post-grouting construction method for realizing the insertion of a pile tip into rock through internal hammering.
FIG. 2 is a schematic structural view of a movable pile shoe;
FIG. 3 is a top view of the movable pile shoe;
fig. 4 is a bottom view of the movable pile shoe;
fig. 5 is an assembly schematic view of a precast tubular pile structure with pile shoes;
fig. 6 is a schematic view of the process of rock entry and post-grouting of the internally hammered pile tip.
The reference numbers in the figures are: the pile comprises a precast tubular pile 1, a movable pile shoe 2, an impact hammer 3, a lifting rope 4, a slurry column 5, a first cylindrical section 201, a second cylindrical section 202, a cross conical pile tip 203, a grouting channel 204, a pile soil layer A and a rock stratum B.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The technical characteristics in the embodiments of the present invention can be combined correspondingly without mutual conflict.
In the description of the present invention, it should be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or be indirectly connected to the other element, i.e., intervening elements may be present. In contrast, when an element is referred to as being "directly connected" to another element, there are no intervening elements present.
In the description of the present invention, it is to be understood that the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature.
In a preferred embodiment of the present invention, as shown in fig. 1, a post-grouting construction method for a precast tubular pile is provided, in which a pile tip is inserted into a rock by internal hammering, and the concept of the present invention is to manufacture a movable pile shoe that can be embedded inside the precast tubular pile, first press the precast tubular pile to a certain depth by static pressure or hammering, then hammer the pile shoe from the inside of the tubular pile by internal hammering to make the pile tip reach a designed rock stratum, and finally perform post-grouting from the inside of the tubular pile to complete the construction. The method comprises the following basic steps:
step 1, after the paying-off positioning is carried out on the surface of the foundation, the prefabricated movable pile shoe 2 is placed at the positioning point position of the surface of the foundation.
It should be noted that the paying-off positioning of the foundation surface can be performed before the precast tubular pile 1 and the movable pile shoe 2 enter the field in the construction preparation stage. And after the surface of the foundation is paid off and positioned in advance according to the design requirements of the pile foundation, the subsequent post-grouting construction method for the precast tubular pile is respectively executed on the positioning point of each pile.
And 2, vertically hoisting the prefabricated tubular pile 1, aligning the prefabricated tubular pile 1 with the movable pile shoe 2, then putting down the prefabricated tubular pile, enabling the first cylindrical section 201 of the movable pile shoe 2 to extend into the bottom of the inner cavity of the prefabricated tubular pile 1, maintaining an annular gap between the prefabricated tubular pile and the movable pile shoe, enabling grouting slurry to permeate into the annular gap, supporting the bottom pile end of the prefabricated tubular pile 1 on the top surface of the second cylindrical section 202, and enabling the tip of the cross conical pile tip 203 to be vertically downward, so that a prefabricated tubular pile structure with pile shoes is formed in an assembling mode.
The novel large-rigidity movable pile shoe is manufactured, so that the effects of increasing the rock entering depth and protecting the pile body are achieved in the rock entering process of the tubular pile, and the effect of improving the bearing capacity of the prefabricated tubular pile is achieved. As shown in fig. 2, 3 and 4, the movable pile shoe 2 comprises a first cylindrical section 201, a second cylindrical section 202 and a cross-tapered pile tip 203. The first cylindrical section 201, the second cylindrical section 202 and the cross-shaped conical pile tip 203 are coaxially and fixedly connected from top to bottom. The diameter of the first cylindrical section 201 is smaller than the inner diameter of the precast tubular pile 1, and the diameter of the second cylindrical section 202 is the same as the outer diameter of the precast tubular pile 1.
Referring to fig. 5, the movable pile shoe 2 is located at the bottom of the precast tubular pile 1 in the assembled state, so as to form a complete precast tubular pile structure with pile shoes. And in the prefabricated tubular pile structure with the pile shoe formed after assembly, the first cylindrical section 201 extends into the bottom of the inner cavity of the prefabricated tubular pile 1, and the horizontal displacement of the first cylindrical section and the horizontal displacement of the prefabricated tubular pile are relatively fixed. However, the first cylindrical section 201 is not completely tightly fixed with the inner cavity of the precast tubular pile 1, and an annular gap which can allow grouting slurry to permeate is maintained between the first cylindrical section and the inner cavity of the precast tubular pile 1. The specific size of the annular gap can be determined according to the actual type of grouting slurry, and the gap width is preferably selected to be as small as possible under the condition that the grouting slurry can smoothly permeate into the annular gap. And the top surface of the second cylindrical section 202 is used as a pile end supporting surface, the bottom pile end of the precast tubular pile 1 is supported on the top surface of the second cylindrical section 202, and the tip of the cross-shaped conical pile tip 203 faces downwards. Under the precast tubular pile structure, the cross conical pile tip 203 plays a role in breaking soil and rock, and the power for breaking soil and rock downwards by the cross conical pile tip 203 is derived from the gravity of the precast tubular pile 1 on one hand and the impact force received by the top of the first cylindrical section 201 in the movable pile shoe 2 on the other hand. The traditional movable pile shoe 2 is fixedly matched with the precast tubular pile 1, the impact force of pile sinking needs to act on the precast tubular pile 1, but the compressive stress of the pile body is increased sharply after the pile body of the precast tubular pile 1 enters a bearing layer, and the higher the rigidity of the bearing layer is, the larger the compressive stress of the pile body is. Therefore, under the repeated action of pressure and tensile stress, severe damage can occur especially at the joint of two piles. In the present embodiment, the movable pile shoe 2 is fitted to the bottom of the precast tubular pile 1 in a non-fixed manner, and the pile bottom end face of the precast tubular pile 1 is supported only on the movable pile shoe 2, but the movable pile shoe 2 and the precast tubular pile 1 can move relatively in the axial direction of the pile body due to the annular gap. Therefore, the movable pile shoe 2 can be impacted downwards into the rock stratum only by applying impact force on the movable pile shoe 2. At the moment of impact, the pile body of the precast tubular pile 1 does not sink along with the pile shoe under the action of soil around the pile, and the pile body of the precast tubular pile 1 sinks under the action of self gravity after the movable pile shoe 2 is opened out of the channel. Therefore, the novel large-rigidity movable pile shoe which is not directly fixed can reduce the compressive stress of the pile body after entering the bearing stratum, ensure the integrity of the pile body and further ensure that the precast pile is smoothly driven into the bedrock.
However, since the movable pile shoe 2 and the precast tubular pile 1 are not fixed, the precast tubular pile to be subsequently precast needs to be grouted after entering the bearing stratum, so that the movable pile shoe and the precast tubular pile form a stable connection structure to support the load above. The grouting slurry is injected through the inner cavity of the precast tubular pile 1, the slurry is accumulated at the top of the first cylindrical section 201, and since an annular gap which enables the grouting slurry to permeate is maintained between the first cylindrical section 201 and the inner cavity of the precast tubular pile 1, the grouting slurry can further permeate from the annular gap to close the annular gap between the first cylindrical section 201 and the inner cavity of the precast tubular pile 1.
Further, during the process that the movable pile shoe 2 enters the rock stratum, the rock stratum can be crushed to form detritus, and when the top surface of the second cylindrical section 202 of the movable pile shoe 2 is separated from the bottom pile end face of the precast tubular pile 1, the detritus can be squeezed between the top surface of the second cylindrical section 202 and the bottom pile end face of the precast tubular pile 1 under the action of the side stress of an external rock body, and the filling of the detritus can improve the uplift bearing capacity of the pile foundation.
In order to further improve the integrity between the crushed rocks, as shown in fig. 3, a plurality of radial grouting channels 204 are formed on the top surface of the second cylindrical section 202 in the present embodiment. The grouting channel 204 is used for introducing grouting slurry into the crushed rock filling area from the annular gap, and the crushed rock is bonded into a whole by the grouting slurry, so that the support of the end part of the precast tubular pile 1 is enhanced. In this embodiment, the grouting channel 204 may radially penetrate through the annular top surface of the second cylindrical section 202, that is, one end of the grouting channel 204 communicates with a position attached to the sidewall of the first cylindrical section 201, and the other end communicates with a position where the sidewall of the second cylindrical section 202 is located. Thus, grouting fluid is injected into the crushed rock fill area along the annular gap and the grouting channels 204 while continuing to partially extend into the rock formation on the side of the pile end, strengthening the integrity between the pile structure and the rock formation. In fig. 3, 4 grouting channels 204 are uniformly arranged on the annular top surface of the second cylindrical section 202 along the circumferential direction, but in practical cases, the number of the grouting channels 204 can be adjusted according to actual needs.
In addition, the cross-shaped tapered pile tip 203 in this embodimentBag (bag)Comprises an end plate and a cross pile tip arranged on the end plate. To ensure the integrity between the cross-shaped tapered pile tip 203 and the second cylindrical section 202, the end plate needs to be attached to the bottom surface of the second cylindrical section 202. The material of the first cylindrical section 201 and the second cylindrical section 202 may be steel or a high-strength reinforced concrete material. If the first cylindrical section 201 and the second cylindrical section 202 are made of steel, the end plate may also be made of steel plate, and the end plate and the bottom surface of the second cylindrical section 202 may be directly welded and fixed. If the first cylindrical section 201 and the second cylindrical section 202 are employedWith reinforced concrete material, the steel end plate can be embedded directly in the second cylindrical section 202, which preferably pre-welds the end plate with the steel bars inside the second cylindrical section 202. As shown in fig. 4, in the cross-shaped conical pile tip 203, three triangular steel plates are welded on a round end plate made of steel to form the cross-shaped pile tip; one of the steel plates is an isosceles triangle steel plate, the bottom edge of the steel plate is arranged along the diameter of the end plate and is welded and fixed, the other two steel plates are right-angled triangle steel plates and are respectively and vertically arranged at two sides of the isosceles triangle steel plate, one right-angled edge of each right-angled triangle steel plate is arranged along the radius of the circular end plate and is welded and fixed, and the other straight edge of each right-angled triangle steel plate is welded and fixed with the side surface of the isosceles triangle steel plate.
It should be noted that, when the first cylindrical section 201 and the second cylindrical section 202 are made of reinforced concrete, they may be integrally cast, or when they are made of steel, they may also be integrally formed, and they are not necessarily divided into two separate parts.
In addition, in order to realize impact pile sinking of the movable pile shoe 2, an impact hammer 3 connected with a lifting rope 4 is further arranged in the embodiment, and the size of the impact hammer 3 can freely enter the inner cavity of the precast tubular pile 1 and is used for hammering the top of the movable pile shoe 2 under the control of the lifting rope 4. In this embodiment, the impact hammer 3 is a cylindrical hammer having a diameter smaller than the inner diameter of the precast tubular pile 1. The hoist rope 4 may be a steel rope having sufficient strength. In order to facilitate the construction of the hammering method or the static pressure method, the lifting rope 4 and the impact hammer 3 are not hoisted into the precast tubular pile 1 in advance, and hoisting is carried out after the subsequent construction of the hammering method or the static pressure method is finished.
After the prefabricated pipe pile structure with the pile shoe is assembled, the pile sinking process of the present invention can be started, and the specific implementation steps of the pile sinking process are described below.
And 3, applying sinking pressure to the top of the precast tubular pile 1 by a hammering method or a static pressure method, sinking the whole precast tubular pile structure with the pile shoe into the foundation, and stopping applying the sinking pressure to the top of the precast tubular pile 1 until the movable pile shoe 2 approaches or partially enters a rock stratum B.
It should be noted that in this step, the precast tubular pile 1 and the movable pile shoe 2 are settled synchronously, and the specific sinking depth is determined according to the actual soil conditions. If the rigidity of the shallow rock stratum B is higher, the pile sinking method or the static pressure method can damage the pile body structure of the precast tubular pile 1, the movable pile shoe 2 can be pressed to the surface of the rock stratum B, and then the construction is directly carried out through the internal hammering method of the subsequent step 4 and the step 5; however, if the rigidity of the shallow rock stratum B is low and pile sinking by the hammering method or the static pressure method does not damage the pile body of the precast tubular pile 1, the movable pile shoe 2 may be pressed into the shallow rock stratum B to a certain depth, and then construction may be performed by the internal hammering method in the subsequent steps 4 and 5, as shown in a) of fig. 6.
And 4, suspending the impact hammer 3 at the top of the inner cavity of the prefabricated tubular pile 1, controlling the lifting rope 4 to release the impact hammer 3, enabling the impact hammer to freely fall along the inner cavity of the prefabricated tubular pile 1 under the action of gravity and to be hammered on the top surface of the first cylindrical section 201 of the movable pile shoe 2, drilling the movable pile shoe 2 into the rock stratum B under the action of impact force, enabling the prefabricated tubular pile 1 not to synchronously sink along with the movable pile shoe 2 under the action of side friction resistance of a pile soil layer A, and enabling a settlement height difference to occur between the two.
In order to facilitate the hoisting operation, in this embodiment, the top of the hoisting rope 4 may extend out of the top of the precast tubular pile 1, and be connected to an external hoisting device, such as a hoist crane, a truck crane, or the like. Of course, the pulley assembly may be directly erected on the ground at the top of the precast tubular pile 1, and the impact hammer 3 may be hammered by manually controlling the lifting rope 4, which is not limited thereto.
And 5, continuously repeating the step 4 until the movable pile shoe 2 sinks into a bearing stratum with a specified depth in the rock stratum B, and finally enabling the top surface of the second cylindrical section 202 of the movable pile shoe 2 to be separated from the bottom pile end of the prefabricated pipe pile 1 due to the accumulated sedimentation height difference between the prefabricated pipe pile 1 and the movable pile shoe 2, wherein the first cylindrical section 201 still partially extends into the inner cavity of the prefabricated pipe pile 1, and the bottom end surface of the prefabricated pipe pile 1, the top surface of the second cylindrical section 202 and the outer side surface of the first cylindrical section 201 jointly form an annular groove space with an outward opening. The space of the annular groove is filled with crushed rocks generated in the process of inserting the pile tip into the rocks.
It should be noted that, in the internal hammering construction process, the movable pile shoe 2 rapidly drills into the rock stratum B along with the impact force of the impact hammer 3, but the settlement of the precast tubular pile 1 is not synchronous, and the specific settlement amount needs to be determined according to the pile body and the pile end resistance of the precast tubular pile 1. When the impact hammer 3 is hammered every time, as shown in b) in fig. 6, the impact hammer 3 is lifted and suspended, and then released, the hammering action of the impact hammer 3 is applied to the top of the first cylindrical section 201 of the movable pile shoe 2, so that the movable pile shoe 2 immediately drills downwards in advance after being subjected to impact force, the precast tubular pile 1 does not synchronously sink along with the movable pile shoe 2 under the action of side friction resistance of a soil layer a around the pile, but slowly sinks under the self-weight subsequently, and a dislocation space is formed between the precast tubular pile 1 and the movable pile shoe 2 due to the fact that a settlement difference occurs, as shown in c) in fig. 6. And continuously utilizing the impact hammer 3 to impact, so that the movable pile shoe 2 and the precast tubular pile 1 are gradually sunk into the rock stratum B until reaching the specified depth. In the pile sinking process, broken rocks are gradually filled into a disjointed space between the movable pile shoe 2 and the precast tubular pile 1, and along with the continuous filling of the broken rocks, the single settlement depth of the precast tubular pile 1 is smaller and smaller until the pile end is stably supported, and the precast tubular pile 1 does not settle any more.
The depth of the bearing stratum into which the movable pile shoe 2 needs to be finally drilled is determined according to exploration data and design requirements, and the movable pile shoe 2 preferably needs to be driven into a bearing stratum such as a stroke stratum. After the pile sinking process is finally completed, the post grouting construction can be carried out,
step 6, extending a grouting guide pipe into the prefabricated pipe pile 1 from the top of the inner cavity of the prefabricated pipe pile 1, grouting the prefabricated pipe pile 1, accumulating grouting slurry at the top of the first cylindrical section 201, continuously permeating and filling the annular gap and the gap of crushed rock in the annular groove space, and finally stopping grouting after a section of slurry column 5 with stable height is formed at the top of the first cylindrical section 201; and after the grouting slurry in the precast tubular pile 1 is cured, finishing post-grouting construction of the precast tubular pile.
It should be noted that during the post grouting operation, a slurry column 5 with a certain height should be formed inside the pipe pile to ensure the stability of the pile shoe during the subsequent construction. That is to say, the height of the mud column 5 at the top of the first cylindrical section 201 can not be too low, so that sufficient pressure can press grouting slurry into a gap below, and simultaneously, the mud column 5 after curing can be ensured to stably fix the precast tubular pile 1 and the movable pile shoe 2, and then together with the slurry in the gap below, so that the pile shoe and the inner wall of the tubular pile are reliably connected, the effect of fixing the movable pile shoe is also achieved, and the stability and the integrity of a pile foundation are improved.
Finally, after the grouting slurry is solidified, a pile foundation of a post-grouting precast tubular pile structure based on the above-mentioned inner hammered pile tip rock-entering structure can be obtained, wherein the space of the section of the slurry column 5 at the top of the first cylindrical section 201, the annular gap and the gap of the crushed rock in the annular groove space are all filled with the solidified grouting slurry, as shown in d) in fig. 6.
According to the technical scheme, the inner-hammering precast tubular pile toe rock entering and post-grouting structure and the construction process are designed, the rock entering depth of the precast tubular pile can be effectively increased, the bearing capacity of a pile foundation is improved, the compressive stress of a pile body after the pile body enters a bearing layer can be reduced when the precast pile enters the bearing layer, the integrity of the pile body is ensured, and the precast pile can be smoothly driven into bedrock. Meanwhile, the movable pile tip is fixed through post grouting operation, and the stability of a pile foundation is guaranteed.
The above-described embodiments are merely preferred embodiments of the present invention, which should not be construed as limiting the invention. Various changes and modifications may be made by one of ordinary skill in the pertinent art without departing from the spirit and scope of the present invention. Therefore, the technical scheme obtained by adopting the mode of equivalent replacement or equivalent transformation is within the protection scope of the invention.
Claims (10)
1. A post-grouting construction method for a precast tubular pile by internally hammering the pile tip into rock is characterized by comprising the following steps:
s1, placing a prefabricated movable pile shoe (2) on the surface of a foundation, wherein the movable pile shoe (2) comprises a first cylindrical section (201), a second cylindrical section (202) and a cross conical pile tip (203); the first cylindrical section (201), the second cylindrical section (202) and the cross conical pile tip (203) are coaxially connected and fixed from top to bottom; the diameter of the first cylindrical section (201) is smaller than the inner diameter of the precast tubular pile (1), the diameter of the second cylindrical section (202) is the same as the outer diameter of the precast tubular pile (1), the top surface of the second cylindrical section (202) serves as a pile end supporting surface, and a plurality of radial grouting channels (204) are formed in the top surface of the second cylindrical section;
s2, vertically hoisting the precast tubular pile (1), aligning the precast tubular pile (1) with the movable pile shoe (2), and then lowering the precast tubular pile (1), so that a first cylindrical section (201) of the movable pile shoe (2) extends into the bottom of an inner cavity of the precast tubular pile (1), an annular gap for enabling grouting slurry to permeate is kept between the first cylindrical section and the second cylindrical section, the bottom pile end of the precast tubular pile (1) is supported on the top surface of a second cylindrical section (202), and the tip of a cross conical pile tip (203) is kept to be vertically downward, so that a precast tubular pile structure with a pile shoe is formed through assembly;
s3, applying sinking pressure to the top of the precast tubular pile (1) by a hammering method or a static pressure method, sinking the whole precast tubular pile structure with pile shoes into the foundation, and stopping applying the sinking pressure to the top of the precast tubular pile (1) until the movable pile shoes (2) approach or partially enter a rock stratum (B);
s4, suspending the impact hammer (3) and the top of the inner cavity of the precast tubular pile (1), controlling a lifting rope (4) to release the impact hammer (3), enabling the impact hammer to freely fall along the inner cavity of the precast tubular pile (1) under the action of gravity, hammering the impact hammer on the top surface of a first cylindrical section (201) of the movable pile shoe (2), enabling the movable pile shoe (2) to drill into a rock stratum (B) under the action of impact force, enabling the precast tubular pile (1) not to synchronously sink along with the movable pile shoe (2) under the action of side friction resistance of a soil layer (A) around the pile, and enabling a settling height difference to occur between the impact hammer and the movable pile shoe (2);
s5, continuously repeating the step S4 until the movable pile shoe (2) sinks into a bearing layer with a specified depth in the rock stratum (B), finally enabling the top surface of a second cylindrical section (202) of the movable pile shoe (2) to be separated from the bottom pile end of the prefabricated pipe pile (1) due to the accumulated sedimentation height difference between the prefabricated pipe pile (1) and the movable pile shoe (2), enabling the first cylindrical section (201) to still partially extend into the inner cavity of the prefabricated pipe pile (1), and enabling the bottom end surface of the prefabricated pipe pile (1), the top surface of the second cylindrical section (202) and the outer side surface of the first cylindrical section (201) to jointly form an annular groove space with an outward opening; the space of the annular groove is filled with crushed rocks generated in the process that the pile tip enters the rocks;
s6, a grouting guide pipe extends into the prefabricated pipe pile (1) from the top of an inner cavity of the prefabricated pipe pile (1), grouting is conducted in the prefabricated pipe pile (1), grouting slurry is accumulated at the top of the first cylindrical section (201) and continuously permeates into and fills the annular gap and the gap of crushed rocks in the annular groove space, and finally grouting is stopped after a section of slurry column (5) with stable height is formed at the top of the first cylindrical section (201); and after the grouting slurry in the precast tubular pile (1) is cured, finishing post-grouting construction of the precast tubular pile.
2. The post-grouting construction method for the precast tubular pile for realizing the pile tip rock penetration through the internal hammering according to the claim 1, characterized in that before the movable pile shoe (2) is precast, the height of the first cylindrical section (201) is designed according to the depth of the movable pile shoe (2) which should sink into the rock stratum (B), so as to ensure that the first cylindrical section (201) is still partially positioned in the precast tubular pile (1) after the movable pile shoe (2) sinks to the specified depth, and the complete separation of the first cylindrical section and the precast tubular pile is avoided.
3. The precast tubular pile post-grouting construction method for driving a pile tip into rock by internal hammering as claimed in claim 1, wherein the lifting rope (4) connected to the impact hammer (3) is controlled by an external hoisting device.
4. The post-grouting construction method for the precast tubular pile for realizing the driving of the pile tip into the rock by internal hammering as claimed in claim 1, wherein the cross-shaped conical pile tip (203) comprises an end plate and a cross-shaped pile tip arranged on the end plate, and the end plate is fixedly attached to the bottom surface of the second cylindrical section (202).
5. The post-grouting construction method of the precast tubular pile for realizing the insertion of the pile toe into the rock by the internal hammering according to claim 4, characterized in that in the cross-shaped conical pile toe (203), the cross-shaped pile toe is formed by welding three triangular steel plates on a steel round end plate; one of the steel plates is an isosceles triangle steel plate, the bottom edge of the steel plate is arranged along the diameter of the end plate and is welded and fixed, the other two steel plates are right-angled triangle steel plates and are respectively and vertically arranged at two sides of the isosceles triangle steel plate, one right-angled edge of each right-angled triangle steel plate is arranged along the radius of the circular end plate and is welded and fixed, and the other straight edge of each right-angled triangle steel plate is welded and fixed with the side surface of the isosceles triangle steel plate.
6. The precast tubular pile post-grouting construction method for achieving the driving of the pile tip into the rock by internal hammering as claimed in claim 1, characterized in that the material of the first cylindrical section (201) and the second cylindrical section (202) is steel or reinforced concrete material.
7. The precast tubular pile post grouting construction method for achieving the driving of a pile tip into rock by internal hammering as claimed in claim 1, wherein the grouting channel (204) radially penetrates the annular top surface of the second cylindrical section (202).
8. The precast tubular pile post-grouting construction method for driving a pile tip into rock by internal hammering as claimed in claim 1, wherein a plurality of grouting channels (204) are uniformly arranged on the annular top surface of the second cylindrical section (202) in the circumferential direction.
9. The post-grouting construction method of the precast tubular pile for realizing the penetration of the pile tip into the rock by the internal hammering as claimed in claim 1, characterized in that the lifting rope (4) is a steel rope.
10. The post-grouting construction method of a precast tubular pile for driving a pile toe into rock according to claim 1, wherein in the construction preparation stage, the surface of the foundation is positioned by paying off in advance according to the design requirements of the pile foundation, and the post-grouting construction method of the precast tubular pile is performed for each positioning point of each pile.
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| CN202210981228.8A CN115233668A (en) | 2022-08-16 | 2022-08-16 | Post-grouting construction method for precast tubular pile by internally hammering pile tip into rock |
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| CN202210981228.8A CN115233668A (en) | 2022-08-16 | 2022-08-16 | Post-grouting construction method for precast tubular pile by internally hammering pile tip into rock |
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