A cast-in-place pile post grouting construction process

Abstract

The application relates to the technical field of pile foundation construction, in particular to a bored pile post-grouting construction process, which comprises the following steps: S1, a preparation stage: determining the type, proportion and preparation method of grouting material, preparing grouting equipment and performing necessary preparation work on a construction site; S2, grouting hole treatment: firstly, the reserved grouting hole needs to be cleaned and treated to ensure the permeability and sealing property of the hole; S3, grouting equipment setting: installing the grouting equipment; S4, grouting injection: prefabricated cement slurry or other grouting material is injected into the pile or the soil layer around the pile through the grouting pipeline until the filling reaches the position required by the design; S5, grouting slurry solidification: waiting for the grouting slurry to be fully solidified to form an integrated structure which is well combined with the pile body and the surrounding soil body. The application has the effect of improving the bearing capacity of the pile foundation.

Description

Technical Field

[0001] This application relates to the technical field of pile foundation construction, and in particular to a post-grouting construction process for bored cast-in-place piles. Background Technology

[0002] Currently, the foundation type for foundation construction in my country generally adopts cast-in-place pile foundations. To meet design requirements, the bearing stratum for cast-in-place piles is required to be a relatively intact rock layer. The pile length and diameter are often very large, resulting in the underground portion accounting for a significant portion of the total project cost. Furthermore, the long pile length creates considerable difficulties during construction. In some regions of my country, the topography belongs to alluvial plain units at the foot of mountains. After passing through the clay layer, the geology consists of a thick layer of gravel. Could this stratum be reinforced to meet design requirements and serve as the bearing stratum for the foundation? Based on this consideration, Chinese designers and construction workers, through years of exploration and practice, have summarized a method for reinforcing the pile tip foundation using a post-drilling grouting method for cast-in-place piles. This method significantly shortens the pile length and achieves good economic benefits.

[0003] Reinforcement mechanism: During the construction of cast-in-place piles, steel pipes are embedded along the outer wall of the pile reinforcement cage. After the pile concrete strength meets the requirements, cement grout is injected into the pores of the crushed stone layer at the pile end through the steel pipe under pressure, so that the originally loose sediment, crushed stone, soil particles and cracks are cemented into a high-strength composite.

[0004] Under pressure, the cement grout diffuses from the pile tip into the pores of the crushed stone layer. For a single pile, this diffusion in all directions is equivalent to increasing the diameter of the end, while the downward diffusion is equivalent to increasing the pile length. In a group of piles, all the grout flows together, making the crushed stone layer a whole, thus enabling the previously unsatisfactory crushed stone layer to meet the structural bearing capacity requirements.

[0005] During the construction of bored piles, no matter how the hole is cleaned, some sediment will remain at the bottom of the hole. During the initial pouring, the concrete falls from the slender guide pipe, and the large drop causes the concrete at the bottom of the pile to segregate, forming "virtual peaks" and "dry gravel". The mud skin on the hole wall hinders the bonding between the pile body and the surrounding soil and reduces the friction coefficient. All of these factors affect the end bearing capacity and side wall friction of the bored pile.

[0006] Therefore, a grouting construction process was designed. After the grout is injected into the pile end, it first combines with the sediment, segregated "virtual tip", and "dry stone" at the pile end to enhance the compactness of this part and improve the bearing capacity. The grout returns along the bonding layer between the pile body and the soil layer, eliminating mud skin and increasing the frictional resistance of the pile side. At the same time, the grout penetrates laterally into the soil layer on the side of the pile, which also increases the pile diameter. Summary of the Invention

[0007] In order to improve the bearing capacity of pile foundations, this application provides a post-grouting construction process for bored cast-in-place piles.

[0008] This application provides a post-grouting construction process for bored cast-in-place piles, which adopts the following technical solution:

[0009] A post-grouting construction process for bored cast-in-place piles includes the following steps:

[0010] S1. Preparation stage: Determine the type, proportion and preparation method of grouting materials, prepare grouting equipment and carry out necessary preparations at the construction site;

[0011] S2. Grouting hole treatment: First, the reserved grouting holes need to be cleaned and treated to ensure the permeability and sealing of the holes;

[0012] S3. Grouting equipment setup: Install grouting equipment;

[0013] S4. Grouting: Pre-prepared cement grout or other grouting materials are injected into the pile or the surrounding soil layer through grouting pipes until the design requirements are met.

[0014] S5. Grouting slurry curing: Wait for the grouting slurry to fully cure, forming an integrated structure that is well bonded to the pile body and the surrounding soil.

[0015] By adopting the above technical solution, after the cast-in-place pile is poured, the grouting material is determined and prepared into a grout. Then, the surrounding area is cleaned, the reserved grouting holes are cleaned, and the grouting equipment is installed. The grout is injected into the pile or the surrounding soil layer through the grouting pipe. Then, the grout is allowed to fully solidify, forming a good integrated structure between the pile body and the surrounding soil. The grouting process is simple. During grouting, the grout returns along the bonding layer between the pile body and the soil layer, eliminating mud skin and increasing the pile side friction. At the same time, the grout penetrates laterally into the soil layer next to the pile, which also increases the pile diameter and improves the bearing capacity of the pile foundation.

[0016] Optionally, grouting can be performed in stages, with the grouting pressure gradually increasing.

[0017] By adopting the above technical solution, grouting is carried out in stages during post-grouting. In order to facilitate full contact between the grout and the soil, the grouting pressure can be gradually increased to ensure full contact between the grout and the soil. The staged grouting method allows the bottom layer of grout to fully penetrate and solidify to a certain extent before the upper layer of grouting is carried out, and the pressure is gradually increased to improve the grouting effect and further improve the bearing capacity of the pile foundation.

[0018] Optionally, intermittent grouting may be used for each grouting section, with the grouting pressure gradually increased.

[0019] By adopting the above technical solution, intermittent grouting is carried out during each grouting process, which causes the grout to pulsate intermittently. Then, the pressure is gradually increased to allow the grout to fully penetrate and improve the grouting effect. The grout then flows upward along the bonding layer between the pile body and the soil layer, eliminating mud skin and increasing the frictional resistance of the pile side. At the same time, the grout's lateral penetration into the soil layer next to the pile also increases the pile diameter, further improving the bearing capacity of the pile foundation.

[0020] Optionally, the grouting pipe includes a main pipe and a secondary pipe. The main pipe is provided with multiple grouting holes. The secondary pipe is coiled around multiple main pipes and extends above the ground. The secondary pipe is connected to the bottom of the main pipe.

[0021] By adopting the above technical solution, when performing grouting work, the main pipe is connected to the grouting equipment. Then, the grouting equipment injects grout into the main pipe. The main pipe grouts the bottom of the cast-in-place pile and grouts other parts of the cast-in-place pile through the auxiliary pipe, which improves the grouting efficiency, provides a grout diffusion channel, facilitates grouting, reduces the difficulty of grout diffusion, and improves the grouting effect.

[0022] Optionally, the main pipe and the auxiliary pipe can be grouted alternately.

[0023] By adopting the above technical solution, during grouting, the main pipe and auxiliary pipe can be used alternately for grouting, so that the grout can be fully diffused, reducing the occurrence of blockage. Furthermore, alternating grouting can increase the activity of grouting, allowing the grout to fully contact the soil and pile body, improving the grouting effect and increasing the bearing capacity of the pile foundation.

[0024] Optionally, a grading pipe is inserted into the main pipe, and multiple sets of grout outlet holes are opened on the grading pipe. The multiple sets of grout outlet holes are set at intervals according to the pouring height of the cast-in-place pile. When performing graded grouting, the grading pipe is slid to make the grout outlet holes communicate with the grouting holes at the corresponding height of the main pipe.

[0025] By adopting the above technical solution and using the set graded pipes, grouting can be carried out in layers, completing the grouting step by step, which improves the convenience of construction, reduces the grouting pressure, and facilitates the rapid progress of grouting.

[0026] Optionally, the main pipe is provided with multiple branch pipes, which are connected to the secondary pipe.

[0027] By adopting the above technical solution, after the grout is injected into the main pipe, the grout diffuses through the main pipe to the secondary pipe via multiple branch pipes, realizing the rapid movement of the grout. Moreover, the multiple connections facilitate the rapid contact of the grout with the soil.

[0028] Optionally, the main pipe is provided with multiple branch pipes, which are connected to the secondary pipes. Both the branch pipes and the secondary pipes are provided with baffles, which are used to divert the slurry discharged from the branch pipes.

[0029] By adopting the above technical solution, when the slurry enters the secondary pipe through the branch pipe, the slurry is diverted by the baffle and enters the secondary pipe separately and moves in two directions, so that the slurry is diffused in layers, which facilitates the rapid filling of the secondary pipe by the slurry, improves the filling degree, and makes the pressure of the multiple outlets consistent, which facilitates the diffusion of the slurry.

[0030] Optionally, the grading pipe is rotatably connected to the main pipe, and the grading pipe is provided with multiple switching holes. Rotating the switching holes can connect the branch pipe or the sub-pipe.

[0031] By adopting the above technical solution, when the grading pipe is rotated, the grading pipe can drive the switching hole to connect with the branch pipe or sub-pipe, completing the switching between the two grouting methods, which facilitates the improvement of grouting effect, makes the grout filling more compact, and improves the grouting effect.

[0032] Optionally, the grading pipe is provided with a marking ruler and a locking assembly. The marking ruler is used to mark the grouting stage. The locking assembly includes a locking ring and a locking post. The locking ring rotates on the main pipe, and the locking post is disposed on the grading pipe. A sliding groove is formed on the inner wall of the locking ring, and the locking post can slide in the sliding groove. An annular groove is formed on the locking ring, and the locking post can slide along the sliding groove into the annular groove.

[0033] By adopting the above technical solution, when performing layered grouting, after the lower layer of grout is filled, the classifier tube is pulled upwards, and then the locking ring is rotated so that the locking column slides from the chute into the ring groove. Then the classifier tube is released, completing the fixation of the classifier tube, and the grouting work continues. The locking component improves the stability of the classifier tube and makes the fixation and adjustment of the classifier tube more convenient, thus improving safety.

[0034] In summary, this application includes the following beneficial technical effects:

[0035] 1. After the cast-in-place pile is poured, the grouting material is determined and prepared into a grout. Then, the surrounding area is cleaned, and the reserved grouting holes are cleaned. Then, the grouting equipment is installed, and the grout is injected into the pile or the surrounding soil layer through the grouting pipe. Then, wait for the grout to fully solidify, forming a good integrated structure between the pile body and the surrounding soil. The grouting process is simple. Through grouting, the grout returns along the bonding layer between the pile body and the soil layer, eliminating mud skin and increasing the frictional resistance of the pile side. At the same time, the grout penetrates laterally into the soil layer next to the pile, which also increases the pile diameter and improves the bearing capacity of the pile foundation.

[0036] 2. After the slurry enters the secondary pipe through the branch pipe, the slurry is diverted by the baffle and enters the secondary pipe separately and moves in two directions, so that the slurry is diffused in layers, which facilitates the rapid filling of the secondary pipe by the slurry, improves the filling degree, and makes the pressure of the multiple outlets consistent, which facilitates the diffusion of the slurry.

[0037] 3. When the grading pipe is rotated, the grading pipe can drive the switching hole to connect with the branch pipe or branch pipe, completing the switching between the two grouting methods, which facilitates the improvement of grouting effect, makes the grout filling more compact, and improves the grouting effect;

[0038] 4. When performing layered grouting, after the lower layer of grout is filled, pull the classifier tube upwards, then rotate the locking ring to allow the locking column to slide from the chute into the ring groove, then release the classifier tube to complete its fixation, and continue the grouting work; the locking component improves the stability of the classifier tube and makes its fixation and adjustment more convenient, thus improving safety. Attached Figure Description

[0039] Figure 1 This is a flowchart illustrating the post-grouting construction process for bored piles in the embodiments of this application.

[0040] Figure 2 This is a diagram showing the arrangement of the grouting pipes in the reinforcing mesh in an embodiment of this application;

[0041] Figure 3 This is a diagram illustrating the grouting pipe in an embodiment of this application;

[0042] Figure 4 This is a diagram illustrating the partition in an embodiment of this application;

[0043] Figure 5 This is a cross-sectional view of the supervisor in an embodiment of this application;

[0044] Figure 6 This is a structural diagram of the locking component in an embodiment of this application.

[0045] Reference numerals: 100, main pipe; 110, grouting hole; 200, secondary pipe; 210, grout flow hole; 300, grading pipe; 310, grout outlet hole; 320, switching hole; 400, branch pipe; 500, sub-pipe; 600, partition plate; 700, marking ruler; 800, locking assembly; 810, locking ring; 811, sliding groove; 812, ring groove; 820, locking post; 830, fixing seat; 840, first sealing ring; 850, second sealing ring; 870, stop ring; 880, limit ring; 900, ring pipe. Detailed Implementation

[0046] The following is in conjunction with the appendix Figures 1-6 This application will be described in further detail.

[0047] This application discloses a post-grouting construction process for bored cast-in-place piles.

[0048] refer to Figure 1 The post-grouting construction process for bored piles includes the following steps:

[0049] S1. Preparation stage: Determine the type, proportion and preparation method of grouting materials, prepare grouting equipment and carry out necessary preparations at the construction site;

[0050] Specifically, based on the construction depth, diameter, construction environment, working conditions, and design specifications of the cast-in-place piles, the type, proportion, and configuration method of the grouting material are selected. Then, the grouting equipment is hoisted to the grouting location, and the pipeline is hoisted to the grouting location.

[0051] S2. Grouting hole treatment: First, the reserved grouting holes need to be cleaned and treated to ensure the permeability and sealing of the holes;

[0052] Specifically, clean the holes, removing debris, fallen leaves, and other contaminants, and check for any foreign objects blocking the holes, removing them promptly.

[0053] S3. Grouting equipment setup: Install grouting equipment;

[0054] Specifically, the grouting equipment is connected to the grouting pipe pre-embedded in the cast-in-place pile via a pipe. To facilitate the installation of the grouting equipment, a flexible hose can be used for the pipe.

[0055] S4. Grouting: Pre-prepared cement grout or other grouting materials are injected into the pile or the surrounding soil layer through grouting pipes until the design requirements are met.

[0056] Specifically, cement grout or other grouting materials prepared according to the design ratio are injected into the grouting pipe through grouting equipment. The grout then enters the pile or the surrounding soil layer through the grouting pipe until the filling pressure reaches the design requirements and the grout moves to the designated position, thus completing the grouting work. Grouting is performed in segments. The height of each segment can be selected between 2m and 3.5m, depending on the pile diameter and soil structure. The pressure of multiple grouting segments gradually increases from the bottom to the top, with the initial pressure meeting the design pressure. The pressure increase range is between 0.3-0.5MPa, which can be appropriately increased according to the height of the cast-in-place pile, but should not exceed 1MPa. Intermittent grouting can also be used for each segment, with the grouting pressure gradually increased within the pressure increase range of the next segment to improve the grouting effect.

[0057] S5. Grouting slurry curing: Wait for the grouting slurry to fully cure, forming an integrated structure that is well bonded to the pile body and the surrounding soil.

[0058] Specifically, after the grout is fully injected, wait for the grout to solidify and check whether it is well bonded to the pile body and the surrounding soil. The check can be done by detection or sampling test.

[0059] refer to Figure 2 , Figure 3 and Figure 4 The aforementioned grouting pipeline includes multiple main pipes 100, each cylindrical and welded to a reinforcing mesh. The main pipes 100 are evenly spaced along the circumference of the cast-in-place pile. A ring pipe 900 is fixedly connected to the bottom of each main pipe 100 via a branch pipe. The bottom of each main pipe 100 is pointed, and both the main pipes 100 and the ring pipe 900 have multiple grouting holes 110. A secondary pipe 200 is spirally arranged on the outer side of each main pipe 100. Located outside multiple main pipes 100 and spirally extending to the ground with multiple slurry flow holes 210, the spiral pipe is fixedly connected to multiple branch pipes 500 and branch pipes 400, with the branch pipes 500 and branch pipes 400 correspondingly arranged, and the spiral pipe is connected to the main pipes 100 through the branch pipes 500 and branch pipes 400 respectively. Each branch pipe 500 is fixedly connected to a baffle 600, which extends into the spiral pipe to separate the spiral pipe and divide the branch pipe 500 into two channels for diverting the slurry.

[0060] During grouting, the main pipe 100 and the auxiliary pipe 200 can be used alternately for grouting, which makes it easier to change the movement path of the grout and make the grout injection more compact.

[0061] refer to Figure 2 , Figure 3 and Figure 5 To facilitate segmented grouting, a grader pipe 300 is inserted into the main pipe 100. The grader pipe 300 is slidably connected to the inner wall of the main pipe 100 and can be rotatably connected within the main pipe 100. Multiple sets of switching holes 320 are provided on the grader pipe 300, each set containing multiple switching holes 320. The multiple sets of switching holes 320 are spaced according to the pouring height of the cast-in-place pile. Each set of switching holes 320 is formed in a waist shape along the curvature of the grader pipe 300. The switching holes 320 can communicate with the branch pipe 500 or the sub-pipe 400, and the switching holes 320 are completely connected to the branch pipe 500. When connected, it is not connected to the branch pipe 400; or when connected to the channel of the branch pipe 500 near the branch pipe 400, it can be connected to half of the branch pipe 400; the grader pipe 300 is also provided with multiple sets of slurry outlet holes 310, which are set at intervals like the switching hole 320; the slurry outlet holes 310 are also waist-shaped, and the slurry outlet holes 310 are always connected to the grouting hole 110 as the grader pipe 300 rotates. When the grader pipe 300 slides, the lower slurry outlet hole 310 is misaligned with the grouting hole 110, and the diameter of the grouting hole 110 is smaller than the diameter of the branch pipe 500 and the branch pipe 400.

[0062] refer to Figure 5 and Figure 6 A marking ruler 700 is fixedly connected to the grading tube 300. The marking ruler 700 has several marking scales according to the number of segments. A locking assembly 800 is provided on the grading tube 300. The locking assembly 800 includes a fixing seat 830 detachably connected to the main tube 100. A placement groove is opened between the fixing seat 830 and the main tube 100, and a first sealing ring 840 is placed in the placement groove. A locking ring 810 is rotatably connected to the fixing seat 830. The locking ring 810 is sleeved on the grading tube 300. Two sliding grooves 811 are opened vertically on the inner wall of the locking ring 810. The grading tube 300 is fixedly connected to... There are multiple locking pins 820, preferably two in this embodiment. The two locking pins 820 slide in two sliding grooves 811 respectively. Three sets of annular grooves 812 are provided on the inner wall of the locking ring 810. The annular grooves 812 are connected to the sliding grooves 811. The interval between the annular grooves 812 corresponds to the segmented injection of the grader tube 300. The locking pins 820 can slide along the sliding grooves 811 into the annular grooves 812. The locking pins 820 can abut against the side wall of the annular grooves 812 near the branch tube 400. A sealing groove is provided on the fixing seat 830. A second sealing ring 850 is placed in the sealing groove. The second sealing ring 850 abuts against the locking ring 810 and can slide relative to the locking ring 810.

[0063] To further secure the grading tube 300, a stop ring 870 is threaded onto the locking ring 810. The stop ring 870 has a relief groove, and the locking pin 820 can slide along the slide groove 811 into the relief groove. A wedge-shaped limiting ring 880 is fixedly connected to the stop ring 870. The limiting ring 880 is inserted between the locking ring 810 and the grading tube 300, and the wedge surface of the limiting ring 880 can abut against the inner wall of the locking ring 810 and undergo slight deformation to abut against the grading tube 300.

[0064] The implementation principle of the post-grouting construction process for bored cast-in-place piles in this application embodiment is as follows: After the cast-in-place pile is poured, the grouting material is determined and prepared into a grout. Then, the surrounding area is cleaned, and the reserved grouting holes are cleaned. The grouting equipment is then installed, and its pipeline is connected to the grader pipe 300. The grout is then injected through the grader pipe 300 into the grouting hole 110 and the secondary pipe 200, and then enters the pile or the surrounding soil layer through the grout flow hole 210 on the secondary pipe 200. The injection process is intermittently stopped, and then the pressure is gradually increased. During the intermittent process, the grader pipe is rotated. 300 allows the grading pipe 300 to switch to the branch pipe 500 or the branch pipe 400, achieving full grouting. After the first stage of grouting is completed, the grading pipe 300 is moved upward so that the grout outlet 310 connects with the grouting hole 110 of the second stage. Then, the locking ring 810 is rotated so that the locking column 820 slides into the ring groove 812. Then, the stop ring 870 is tightened. After a short period of stillness, the second stage of grouting is carried out. The grouting process repeats the grouting steps of the first stage. After all the grouting is completed, the grout is allowed to fully solidify, forming a good integrated structure of the pile body and the surrounding soil, which can then be inspected.

[0065] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A post-grouting construction process for bored cast-in-place piles, characterized in that, include S1. Preparation stage: Determine the type, proportion and preparation method of grouting materials, prepare grouting equipment and carry out necessary preparations at the construction site; S2. Grouting hole treatment: First, the reserved grouting holes need to be cleaned and treated to ensure the permeability and sealing of the holes; S3. Grouting equipment setup: Install grouting equipment; S4. Grouting: Pre-prepared cement grout or other grouting materials are injected into the pile or the surrounding soil layer through grouting pipes until the design requirements are met. S5. Grouting slurry curing: Wait for the grouting slurry to fully cure, forming an integrated structure that is well bonded to the pile body and the surrounding soil; The grouting pipe includes a main pipe (100) and a secondary pipe (200). The main pipe (100) is provided with multiple grouting holes (110) and the secondary pipe (200) is arranged around multiple main pipes (100) and extends above the ground. The secondary pipe (200) is connected to the bottom of the main pipe (100). A grading pipe (300) is inserted into the main pipe (100). Multiple sets of grout outlet holes (310) are opened on the grading pipe (300). The multiple sets of grout outlet holes (310) are set at intervals according to the pouring height of the cast-in-place pile. When performing graded grouting, the grading pipe (300) is slid to make the grout outlet hole (310) connect with the grouting hole (110) at the corresponding height of the main pipe (100). The main pipe (100) is provided with a plurality of branch pipes (400), and the branch pipes (400) are connected to the secondary pipes (200); The main pipe (100) is provided with a plurality of branch pipes (500), the branch pipes (500) are connected to the secondary pipes (200), and both the branch pipes (500) and the secondary pipes (200) are provided with baffles (600), the baffles (600) are used to divert the slurry discharged from the branch pipes (500).

2. The post-grouting construction process for bored piles according to claim 1, characterized in that, During grouting, segmented grouting is adopted, and the grouting pressure is gradually increased.

3. The post-grouting construction process for bored piles according to claim 1, characterized in that, Intermittent grouting was used for each section of grouting, with the grouting pressure gradually increasing.

4. The post-grouting construction process for bored piles according to claim 1, characterized in that, The main pipe (100) and the auxiliary pipe (200) can be grouted alternately.

5. The post-grouting construction process for bored piles according to claim 1, characterized in that, The grader tube (300) is rotatably connected inside the main tube (100). The grader tube (300) is provided with a plurality of switching holes (320). The switching holes (320) can be rotated to connect the branch tube (500) or the branch pipe (400).

6. The post-grouting construction process for bored piles according to claim 5, characterized in that, The grading pipe (300) is provided with a marking ruler (700) and a locking assembly (800). The marking ruler (700) is used to mark the grouting stage. The locking assembly (800) includes a locking ring (810) and a locking post (820). The locking ring (810) rotates on the main pipe (100). The locking post (820) is provided on the grading pipe (300). A sliding groove (811) is provided on the inner wall of the locking ring (810). The locking post (820) can slide in the sliding groove (811). An annular groove (812) is provided on the locking ring (810). The locking post (820) can slide along the sliding groove (811) into the annular groove (812).

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