A cast-in-place pile construction system and method

Abstract

This invention provides a cast-in-place pile construction system, comprising: a full-casing drilling rig for driving the casing to advance in sections to drill holes; a soil-extraction drilling rig for excavating soil within the casing during its advancement; a hoisting device for hoisting construction components, including a reinforcing cage, guide pipe, and casing; a grouting device for injecting concrete into the hole; and an inclination information acquisition device connected to the casing gripper of the full-casing drilling rig for acquiring the inclination information of the casing. By controlling the bottom of the steel casing to always advance at least 2m ahead of the soil extraction surface, advanced support is achieved, eliminating the need for mud wall protection and completely eliminating the risk of hole collapse in the riprap backfill layer. Feedback adjustment of the casing's verticality reduces the verticality deviation of the pile. Mechanical hard cutting is performed within the golden window period of 5-8 MPa strength after the plain pile is poured, improving the integrity of the interlocking surface and reducing the deviation in interlocking thickness.

Description

Technical Field

[0001] This invention relates to the field of cast-in-place pile construction technology, and in particular to a cast-in-place pile construction system and method. Background Technology

[0002] In existing technologies, interlocking cast-in-place piles are widely used in deep foundation pit support and seepage prevention projects due to their advantages such as continuous seepage prevention and good integrity. Traditional construction methods mainly employ rotary drilling with mud slurry wall protection, but in complex strata (such as rubble backfill layers and highly permeable sand layers), the following technical defects exist: First, the risk of borehole collapse is difficult to control. In rubble backfill layers, due to the large gaps and strong connectivity between the rubble, mud slurry is easily lost, making it impossible to form an effective mud cake for wall protection, leading to borehole wall collapse, diameter reduction, and in severe cases, even failure to form a pile. Simultaneously, existing construction methods lack real-time monitoring and dynamic linkage control methods for the relationship between the bottom of the protective casing and the depth of the soil extraction surface inside the casing, failing to ensure that the casing always leads ahead of the soil extraction surface for effective support, resulting in a high risk of borehole collapse. Second, the verticality deviation of the pile body is large, and real-time adjustment methods are lacking. In inclined rock surfaces or strata with uneven hardness, the drill bit is subjected to uneven stress, and the verticality deviation of the pile body is generally between 0.5% and 0.8%, and in some cases even exceeds 1.0%, making it difficult to meet the strict verticality requirements of interlocking piles. Current construction methods rely heavily on manual experience or post-construction inspection, lacking real-time high-precision detection and automatic closed-loop control of casing verticality, resulting in prominent verticality control issues. Summary of the Invention

[0003] This invention provides a cast-in-place pile construction system and method to solve the problem of unstable hole formation quality in the prior art.

[0004] This invention provides a cast-in-place pile construction system, comprising: Full casing drilling rigs are used to drive the casing sections to advance into the formation for drilling operations. A soil-removing drill is used to remove soil from inside the casing during the advancement of the casing. A hoisting device for hoisting construction components, including steel cages, guide pipes, and sleeves; A grouting device used to pour concrete into a hole; An inclination information acquisition device is connected to the casing gripper of the full casing drilling rig and is used to acquire the inclination information of the casing. The industrial control computer is connected to the full casing drilling rig, the soil sampling drilling rig, and the inclination information acquisition device. It is used to adjust the verticality of the casing advance according to the inclination information and to set the minimum depth of the soil sampling surface according to the depth of the bottom end of the casing.

[0005] The present invention also provides a method for constructing cast-in-place piles, which utilizes a cast-in-place pile construction system and includes the following steps: S1. Drill all plain pile holes at preset positions using a full casing drilling rig, and insert concrete guide pipes into the plain pile holes. S2. Concrete is poured into the plain pile hole through a concrete guide pipe, and the casing is gradually removed. S3. After the compressive strength of the concrete in the plain pile hole reaches the preset strength, the drilling operation of all the plain pile holes is carried out by the full casing drilling rig at the preset position, and the steel cage is inserted into the plain pile hole. A plain pile hole is set between each pair of adjacent plain piles, and the two sides of the plain pile hole are cut from the two adjacent plain piles respectively. S4. Insert a concrete guide pipe into the pile hole, pour concrete into the pile hole through the concrete guide pipe, and gradually remove the sleeve. S5. After all the plain and solid piles have solidified, the construction of the cast-in-place piles will be completed.

[0006] Furthermore, during the drilling operations of both the plain pile hole and the solid pile hole, the depth of the bottom end of the casing is always controlled to be at least 2m greater than the depth of the soil extraction surface inside the casing.

[0007] Furthermore, during the drilling operations of both the plain pile hole and the hard pile hole, the verticality of the casing is controlled to not exceed 0.3%.

[0008] Furthermore, the preset strength is set to 5~8MPa.

[0009] Furthermore, during the process of pouring concrete into the solid pile hole and the plain pile hole, the rising speed of the concrete surface is controlled to not exceed 15m / h.

[0010] Furthermore, during the process of pouring concrete into the solid pile hole and the plain pile hole, the bottom of the concrete guide pipe is kept buried in the concrete to a depth of not less than 2m.

[0011] Furthermore, during the drilling operations of the plain pile hole and the rough pile hole, when the drilling depth reaches 3-10m from the preset bearing layer depth, it is determined whether the bearing layer has been reached. When the bearing layer is reached, drilling should be stopped after drilling down to the preset depth; otherwise, drilling should continue for 0.5m and then the situation should be reassessed.

[0012] Furthermore, in step S3, concrete is poured within 4 hours of placing the reinforcing cage.

[0013] Furthermore, during concrete pouring, the pouring height is made to exceed the preset pile top elevation by at least 0.5m.

[0014] The beneficial effects of this invention are as follows: 1. By ensuring the bottom of the steel casing always extends at least 2 meters ahead of the excavation surface, advanced support is achieved, eliminating the need for mud slurry wall protection and completely eliminating the risk of borehole collapse in the riprap backfill layer. Feedback adjustment of the casing's verticality reduces pile verticality deviation.

[0015] 2. Mechanical hard cutting is carried out within the golden window period of 5~8MPa strength after the plain pile is poured to improve the integrity of the interlocking surface, reduce the deviation of the interlocking thickness, and ensure continuous seepage prevention.

[0016] 3. The construction process of alternating plain piles and solid piles was clearly defined, and key parameter standards such as concrete strength, pouring speed, tremie pipe burial depth, and over-pouring height were set. The entire process was parameterized and controlled, which significantly improved the integrity of the pile body, the interlocking density, and the support and seepage prevention effect. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the construction process of plain piles according to an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the construction process of pile foundation according to an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of the distribution of cast-in-place piles according to an embodiment of the present invention.

[0020] Figure 4 This is a schematic diagram of the process for controlling the sleeve tilt angle according to an embodiment of the present invention.

[0021] Figure 5 This is a schematic diagram of the strength-time curve and cutting window of the plain pile in an embodiment of the present invention.

[0022] Figure 6 This is a schematic diagram of the structure of the industrial control computer according to an embodiment of the present invention.

[0023] Figure label: 1. Industrial control computer; 2. Casing depth control module; 3. Strength and time monitoring module; 4. Grouting control module; 5. Verticality sensing module; 6. Bearing layer determination module; 7. Pile top quality compensation module. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0025] The terms "first" and "second" in the specification and claims of this invention may explicitly or implicitly include one or more of those features. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0026] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0027] The following describes a cast-in-place pile construction system of the present invention with reference to the figures, comprising: a full casing drilling rig for driving the casing to advance in sections to perform drilling operations; a soil extraction drilling rig for extracting soil within the casing during the advancement of the casing; a hoisting device for hoisting construction components, the construction components including a reinforcing cage, a guide pipe, and the casing; a grouting device for injecting concrete into the hole; an inclination information acquisition device connected to the casing gripper of the full casing drilling rig for acquiring inclination information of the casing; and an industrial control computer communicatively connected to the full casing drilling rig, the soil extraction drilling rig, and the inclination information acquisition device for adjusting the verticality of the casing advancement according to the inclination information and setting the minimum depth of the soil extraction surface according to the depth of the bottom end of the casing.

[0028] Specifically, the full-casing drilling rig features a hydraulic slewing system, a casing gripper, and adjustable outrigger cylinders. The casing is held by the casing gripper, and the hydraulic slewing system propels the casing into the formation in sections. The adjustable outrigger cylinders adjust the casing's thrust angle. A crawler crane is used for full-slewing repositioning, assisting with slag removal using a grab bucket, and lifting the reinforcing cage. The full-slewing full-casing drilling rig drives the steel casing into the formation in sections. An inclination sensor collects the casing inclination data in real time and transmits it to the industrial control computer. After determining the inclination deviation, the industrial control computer sends adjustment commands to the hydraulic outrigger system to quickly correct the verticality, achieving dual closed-loop real-time control of the casing verticality. Simultaneously, the industrial control computer compares the casing bottom depth with the soil surface depth in real time, achieving mud-free mechanical wall protection through depth locking, thus preventing borehole collapse at its source. The system's collaborative operation adapts to complex formations such as rock backfill layers and highly permeable sand layers, significantly improving construction stability and controllability.

[0029] In some alternative embodiments, a concrete pouring device and a multi-type drill bit assembly are also included. The concrete pouring device is used to pour concrete and is communicatively connected to an industrial control computer. The multi-type drill bit assembly includes a barrel drill, a grab bucket, and an impact hammer, and the multi-type drill bit assembly is switched according to the formation conditions.

[0030] This invention also discloses a method for constructing cast-in-place piles, applied to the aforementioned cast-in-place pile construction system, for constructing interlocking cast-in-place piles, which include plain piles and thick piles arranged in a single row of alternating patterns, such as... Figure 3 As shown in the diagram, A represents a plain pile, and B represents a mixed pile. The plain and mixed piles interlock, with the overlapping portion forming the mixed pile structure. The construction method includes the following steps, as follows: Figure 1 , Figure 2 As shown: S1. Drilling of plain pile holes is carried out using a full casing drilling rig, and a concrete guide pipe is inserted into the plain pile hole. Specifically, steel casing is selected for the casing, and rotary drilling rig is selected for the soil removal drilling rig. At the preset position, the steel casing is pressed into the ground in sections by the full casing drilling rig, and the slag is removed inside the steel casing by the rotary drilling rig. All the plain pile holes are drilled in a 1-3-5-7... skip drilling pattern.

[0031] S2. Concrete is poured into the plain pile hole through a concrete guide pipe, and the casing is gradually removed. Specifically, before pouring concrete, all plain pile holes are emptied and the hole formation quality is checked. Then, a concrete guide pipe is inserted into the plain pile hole to perform a secondary cleaning of the bottom of the hole. After the secondary cleaning, concrete is poured. The initial pour volume must be sufficient, ensuring the guide pipe is buried at a depth greater than 1 meter. During pouring, the bottom of the guide pipe should be buried at least 2 meters into the concrete. The guide pipe should be frequently raised and lowered, with no more than 6 meters removed at a time. During pouring, the concrete surface rising speed should be controlled to ≤15 m / h, completing the pouring of the previous plain pile.

[0032] S3. After the compressive strength of the concrete in the plain pile hole reaches the preset strength, the drilling operation of all the plain pile holes is carried out by the full casing drilling rig at the preset position, and the steel cage is inserted into the plain pile hole. A plain pile hole is set between each pair of adjacent plain piles, and the two sides of the plain pile hole are cut from the two adjacent plain piles respectively. Specifically, after the concrete reaches the preset strength, auxiliary piles are constructed between the two plain piles. All auxiliary pile holes are drilled in a 2-4-6-8... skip drilling pattern. When the auxiliary pile holes are formed, they interlock with the sidewalls of the plain piles, ensuring smooth cutting, a complete interlocking surface, and improved interlocking integrity. Similarly, steel casing is used. The steel casing is driven into the ground in sections using a full-casing drilling rig. Slag is removed from the steel casing using a rotary drilling rig. A auxiliary pile hole is cut between adjacent plain piles, and a reinforcing cage is inserted into the auxiliary pile hole.

[0033] S4. Insert a concrete guide pipe into the pile hole, pour concrete into the pile hole through the concrete guide pipe, and gradually remove the sleeve. Similarly, before pouring concrete, the borehole should be emptied and the drilling quality checked. Then, a concrete tremie pipe should be inserted to perform a second cleaning of the bottom of the borehole. After the second cleaning, concrete should be poured. The initial pour volume must be sufficient, ensuring the tremie pipe is buried at a depth greater than 1 meter. During pouring, the bottom of the tremie pipe should be buried at least 2 meters in concrete. The tremie pipe should be frequently raised and lowered, with no more than 6 meters removed at a time. The concrete surface rise rate should be controlled to ≤15 m / h during pouring to complete the filling of the borehole.

[0034] S5. After all the plain and solid piles have solidified, the construction of the cast-in-place piles will be completed.

[0035] First, the plain piles are constructed. After the plain piles are poured and cured to the target strength, the sidewalls of adjacent plain piles are cut using a full-casing drilling rig, and all intermediate piles are constructed. Strict adherence to the interlocking pile construction logic is maintained, ensuring orderly interlocking of plain and intermediate piles to guarantee continuous seepage prevention and overall load-bearing performance of the pile body. Skip-driving construction avoids disturbance to adjacent piles, reducing the risk of borehole deformation and interlocking failure, and is suitable for large-area interlocking cast-in-place pile support construction.

[0036] Furthermore, during the drilling operations of both plain pile holes and solid pile holes, the depth of the bottom of the casing is always controlled to be at least 2m greater than the depth of the soil extraction surface inside the casing.

[0037] Specifically, during the segmented installation of the steel casing, the depth of the casing bottom and the depth of the soil extraction surface inside the casing are monitored in real time. The depth of the casing bottom is always controlled to be at least 2 meters ahead of the soil extraction surface depth. When the difference in depth is less than 2 meters, the industrial control computer automatically issues an alarm and controls the rotary drilling rig to suspend soil extraction operations, forcibly prioritizing the installation of the casing until the difference in depth is ≥ 2 meters, thus forming a dynamic mechanical wall protection throughout the entire process. By setting the casing bottom to be ahead, borehole collapse can be completely prevented without mud wall protection. This method is suitable for strata prone to borehole collapse, such as backfill layers with ultra-large diameter boulders and high-permeability sand layers. Dry construction is more environmentally friendly and the borehole quality is more stable.

[0038] Specifically, the industrial control computer calculates the current depth information of the bottom end of the casing based on the advance length of the casing. A depth sensor is installed on the soil sampling drill to sense the current soil sampling depth information. The depth sensor is connected to the industrial control computer to make a judgment based on the advance depth difference.

[0039] Furthermore, during the drilling operations of both plain pile holes and solid pile holes, the verticality of the casing is controlled to not exceed 0.3%.

[0040] Specifically, such as Figure 4As shown, an inclination sensor or laser inclinometer is installed on the casing gripper of the casing drilling rig as an inclination information acquisition device, with an acquisition accuracy of 0.01°. Verticality is checked every 3m of casing lowering; the detection data is transmitted to the hydraulic control system in real time. When the deviation angle exceeds a preset threshold (set to 0.15°), the hydraulic outrigger closed-loop system automatically adjusts the outrigger cylinder stroke horizontally within 10 seconds to correct the casing verticality; forming a dual closed-loop control loop of "detection-calculation-execution-re-detection" until the pile verticality is ≤0.3%. The verticality accuracy is more than doubled compared to traditional methods, avoiding interlocking failure and uneven pile stress caused by verticality deviation, ensuring the integrity of the interlocking pile and the stability of the support structure.

[0041] Furthermore, the preset strength is set to 5~8MPa.

[0042] Specifically, after the plain pile is poured, its strength is monitored using on-site test blocks under the same conditions. The pre-set strength for hard cutting of the plain pile is 5-8 MPa. In one specific embodiment, the concrete compressive strength reaches 5-8 MPa 16-28 hours after pouring. Figure 5 As shown, the optimal cutting time window is locked at 24 hours to ensure cutting quality and occlusal effect, resulting in smooth cutting, complete occlusal surface, and occlusal integrity ≥95%.

[0043] Furthermore, during the process of pouring concrete into the solid pile hole and the plain pile hole, the rising speed of the concrete surface should be controlled to not exceed 15m / h.

[0044] Specifically, the concrete surface height is monitored in real time during pouring, and the industrial control computer adjusts the pump flow rate to keep the rising speed within limits. The concrete is dense and uniform, avoiding pores and inclusions, significantly reducing the pouring defect rate. In high-permeability strata, it effectively reduces concrete loss, pipe blockage, inclusions, and pile breakage.

[0045] Furthermore, during the drilling operations of plain pile holes and solid pile holes, when the drilling depth reaches 3-10m from the preset bearing layer depth, it is determined whether the bearing layer has been reached. When the bearing layer is reached, drilling should be stopped after drilling down to the preset depth; otherwise, drilling should continue for 0.5m and then the situation should be reassessed.

[0046] The assessment should be conducted when approaching the designed bearing stratum. Specifically, when the bearing stratum is 3-10m away, determine whether it has been reached. If not, continue drilling for another 0.5m before reassessing. The assessment method can be a comprehensive evaluation combining geological survey data, drill rod vibration, and the identification of soil samples taken each time.

[0047] Furthermore, in step S3, concrete is poured within 4 hours of placing the reinforcing cage.

[0048] Specifically, once the reinforcing cage is lowered, preparations for grouting are made immediately, and concrete pumping is started within 4 hours. During this stage, the sediment at the bottom of the hole is thin, the pile body is intact, and timely pile formation is ensured.

[0049] Furthermore, during concrete pouring, the pouring height is made to exceed the preset pile top elevation by at least 0.5m.

[0050] Specifically, after the initial setting and before the final setting of the concrete, the actual thickness of the laitance layer is measured using a laitance thickness detector or an insertion hammer. The depth of the pile head is dynamically adjusted based on the measurement results to ensure that the concrete strength below the designed pile top meets the design requirements.

[0051] In one specific embodiment, such as Figure 6 As shown, the industrial control computer 1 integrates a casing depth control module 2, a strength and time monitoring module 3, a grouting control module 4, a verticality sensing module 5, a bearing layer determination module 6, and a pile top quality compensation module 7.

[0052] The casing depth control module 2 is used to receive the current soil sampling depth information and calculate the current depth information of the bottom end of the casing based on the advance length of the casing. When the advance depth difference is less than 2m, it automatically issues an alarm and controls the soil sampling drill to suspend soil sampling operation while controlling the full casing drill to advance the preset length. When the advance depth difference is ≥2m, it controls the soil sampling drill to continue soil sampling operation.

[0053] The strength-time monitoring module 3 is used to time the pile hole after the concrete is poured and to set a preset time to meet the compressive strength standard according to the concrete strength-time curve of the concrete. When the preset time is met after the concrete is poured, a control signal is sent to allow the drilling of the pile hole. The pouring control module 4 is used to control the pouring speed of concrete; Verticality sensing module 5 is used to control the extension and retraction of the adjustable outrigger cylinder based on the tilt information collected by the tilt information acquisition device, thereby adjusting the push-in tilt angle of the sleeve. The bearing layer determination module 6 is used to control the casing's advancement action based on the current casing advancement depth information. Specifically, when the drilling depth reaches 3-10m from the preset bearing layer depth, it determines whether the bearing layer has been reached; if the bearing layer has been reached, drilling continues downward to the preset depth and then stops the drilling operation; otherwise, drilling continues for 0.5m and then a new determination is made.

[0054] The pile top quality compensation module 7 is used to adjust the depth of the pile head based on the slurry thickness information.

[0055] Where there is no conflict, the above embodiments and features described herein can be combined with each other.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A cast-in-place pile construction system, characterized in that, include: Full casing drilling rigs are used to drive the casing sections to advance into the formation for drilling operations. A soil-removing drill is used to remove soil from inside the casing during the advancement of the casing. A hoisting device for hoisting construction components, including steel cages, guide pipes, and sleeves; A grouting device used to pour concrete into a hole; An inclination information acquisition device is connected to the casing gripper of the full casing drilling rig and is used to acquire the inclination information of the casing. The industrial control computer is connected to the full casing drilling rig, the soil sampling drilling rig, and the inclination information acquisition device. It is used to adjust the verticality of the casing advance according to the inclination information and to set the minimum depth of the soil sampling surface according to the depth of the bottom end of the casing.

2. A method for constructing cast-in-place piles, characterized in that, The method applied to the cast-in-place pile construction system of claim 1 includes the following steps: S1. Drill all plain pile holes at preset positions using a full casing drilling rig, and insert concrete guide pipes into the plain pile holes. S2. Concrete is poured into the plain pile hole through a concrete guide pipe, and the casing is gradually removed. S3. After the compressive strength of the concrete in the plain pile hole reaches the preset strength, the drilling operation of all the plain pile holes is carried out by the full casing drilling rig at the preset position, and the steel cage is inserted into the plain pile hole. A plain pile hole is set between each pair of adjacent plain piles, and the two sides of the plain pile hole are cut from the two adjacent plain piles respectively. S4. Insert a concrete guide pipe into the pile hole, pour concrete into the pile hole through the concrete guide pipe, and gradually remove the sleeve. S5. After all the plain and solid piles have solidified, the construction of the cast-in-place piles will be completed.

3. The method for constructing cast-in-place piles according to claim 2, characterized in that: During the drilling operations of both the plain pile hole and the solid pile hole, the depth of the bottom of the casing is always controlled to be at least 2m greater than the depth of the soil extraction surface inside the casing.

4. The method for constructing cast-in-place piles according to claim 2, characterized in that: During the drilling operations of both the plain pile hole and the hard pile hole, the verticality of the casing is controlled to not exceed 0.3%.

5. The method for constructing cast-in-place piles according to claim 2, characterized in that: The preset strength is set to 5~8MPa.

6. The method for constructing cast-in-place piles according to claim 2, characterized in that: During the process of pouring concrete into the solid pile hole and the plain pile hole, the concrete surface rising speed shall be controlled to not exceed 15m / h.

7. The method for constructing cast-in-place piles according to claim 2, characterized in that: During the process of pouring concrete into the solid pile hole and the plain pile hole, the bottom of the concrete guide pipe should be embedded in the concrete to a depth of not less than 2m.

8. The method for constructing cast-in-place piles according to claim 2, characterized in that: During the drilling operations of the plain pile hole and the rough pile hole, when the drilling depth reaches 3-10m from the preset bearing layer depth, it is determined whether the bearing layer has been reached. When the bearing layer is reached, drilling should be stopped after drilling down to the preset depth; otherwise, drilling should continue for 0.5m and then the situation should be reassessed.

9. The method for constructing cast-in-place piles according to claim 2, characterized in that: In step S3, concrete is poured within 4 hours of the steel cage being placed.

10. The method for constructing cast-in-place piles according to claim 2, characterized in that: When pouring concrete, the pouring height should exceed the preset pile top elevation by at least 0.5m.

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