Secondary pouring pile forming method for high-cantilever large-diameter slide-resistant pile

Abstract

The invention discloses a secondary pouring pile forming method for a high-cantilever large-diameter slide-resistant pile. The method comprises the steps of surveying and setting out, underground section construction, pile splicing section treatment and cantilever section construction. Firstly, the overall trend, the pile position, the underground section depth and the distance between every two adjacent piles of the slide-resistant pile row wall are designed according to the retaining requirement, the height of a secondary pouring interface is set to be staggered, and a wavy layout is formed to optimize the stress performance; secondly, gravelly soil is backfilled and compacted, a pile splicing section pile casing with the diameter larger than the pile diameter is installed, hole forming construction is conducted, an underground section reinforcement cage is installed, and one-time pouring is completed; after the concrete strength reaches 50%, the pile casing is dismantled, a pile head is chiseled away to form a rough interface, quincunx steel bars are implanted, a high-strength binder is brushed, and a cantilever section steel reinforcement cage is connected; and finally, a cantilever section formwork is installed and fixed, a cable rope is arranged, and cantilever section concrete is poured for the second time to form a pile. According to the method, the integrity, the structural performance and the strength of the pile body are improved by optimizing the secondary pouring interface layout and enhancing the combination of the new concrete and the old concrete.

Description

Technical Field

[0001] The invention relates to the technical field of slope protection, and in particular to a secondary pouring pile forming method for high-cantilever large-diameter anti-slide piles. Background Art

[0002] With the rapid development of infrastructure construction in my country, many roads and factories need to be built on mountainous terrain due to terrain conditions. This terrain feature inevitably requires the use of a large number of retaining structures to ensure the stability and safety of the project. As the main retaining structure to resist lateral earth pressure, anti-slide piles, especially cantilever anti-slide piles, are widely used in slope management, foundation pit support and other projects due to their advantages of saving floor space and increasing available space.

[0003] At present, the construction methods of cantilever piles and manual bored piles for cut slopes are relatively mature, and the construction technology and quality control methods are relatively complete. However, for fill slopes, especially cantilever anti-slide piles constructed by mechanical drilling, there are few successful construction cases in the existing technology, and there is a lack of systematic construction process summary and quality control methods.

[0004] In high fill slope projects, cantilever anti-slide piles usually have the characteristics of large cantilever length (8-10 meters) and large pile diameter (such as 1.8 meters). The traditional one-time continuous pouring pile technology faces many difficulties in this case: due to the heavy weight of the pile body concrete, it is difficult to fix the formwork at the hole, and it is impossible to effectively resist the lateral pressure of the concrete, resulting in difficulty in supporting the formwork, or even impossible to implement.

[0005] In order to overcome the above difficulties, the engineering practice tried to adopt the method of segmented casting, that is, the underground part and the above-ground cantilever part were cast separately. However, this secondary casting method brought new technical difficulties: how to ensure that the high cantilever and large diameter anti-slip piles with mechanical holes can still maintain the integrity and structural performance of the pile body after the secondary casting has become the key to quality control.

[0006] The existing technology lacks mature construction methods for the above problems and cannot effectively solve the integrity and quality problems of high cantilever large diameter anti-slide piles during the secondary pouring process. This not only affects the construction efficiency of the project, but may also have an adverse impact on the slope stability and structural safety.

[0007] Therefore, there is an urgent need for a pile construction method suitable for high cantilever large-diameter anti-slip piles, which can effectively solve the problem of pile body integrity caused by secondary pouring, ensure construction quality, and meet engineering design and specification requirements. Summary of the invention

[0008] The present application provides a secondary casting method for high-cantilever large-diameter anti-slide piles to solve the problems of difficulty in constructing large-diameter anti-slide piles in high fill slope environments and difficulty in ensuring integrity and structural safety.

[0009] According to a first aspect, a secondary casting method for high cantilever large diameter anti-sliding piles is provided, wherein the high cantilever large diameter anti-sliding piles include an underground section, a pile connection section and a cantilever section, and a plurality of high cantilever large diameter anti-sliding piles are arranged at intervals to form an anti-sliding pile row wall, and the pile forming method includes:

[0010] (1) Measurement and setting out:

[0011] According to the support requirements, design the overall direction of the anti-slide pile wall, the position of each anti-slide pile and the depth of the underground section, as well as the spacing between adjacent anti-slide piles;

[0012] The secondary pouring interfaces of each anti-slide pile are set to be staggered to avoid being on the same horizontal plane;

[0013] (2) Underground section construction:

[0014] Backfill gravel soil on the original ground and compact it mechanically to form a construction working surface;

[0015] Burying a pile connection section casing at a preset pile connection section position of the construction working surface, wherein the pile connection section casing is larger than the pile diameter of the underground section;

[0016] The drilling rig performs hole-forming construction in the underground section, and after the hole-forming construction is completed, the quality of the hole is tested;

[0017] The underground section of the steel cage is installed in the hole, and the main reinforcement of the steel cage extends upward to the top of the cantilever section pile to form the full-length main reinforcement;

[0018] Lower the guide tube, pour the underground section concrete and the pile connection section concrete, and complete the pouring in one go;

[0019] (3) Pile connection section processing:

[0020] After the strength of the concrete poured once reaches 50%, the construction working surface is excavated, the pile connection section casing is removed, the pile head of the pile connection section poured once is chiseled off until the coarse aggregate of the concrete is exposed, and the debris on the pile head is cleaned to form a rough bonding interface;

[0021] Several reinforcement bars with the same diameter as the main reinforcement bars of the reinforcement cage are implanted at the pile head of the pile section. The reinforcement bars are evenly distributed along the periphery with the center of the pile section as the base point, forming a plum blossom shape arrangement;

[0022] Install the steel cage of the cantilever section, and mechanically connect or weld the main reinforcement of the steel cage of the cantilever section to the through-length main reinforcement;

[0023] (4) Cantilever section construction:

[0024] Install and fix the template of the cantilever section, wherein the template is anchored to the pile head of the pile connection section by bolts;

[0025] At 2 / 3 of the full height of the formwork, tension no less than three guy ropes evenly distributed downward at 120°. The guy ropes should form an angle of 45° with the ground, and ground anchors should be set at the fixed ends.

[0026] Pour concrete into the formwork and add concrete accelerator;

[0027] The cantilever section is vibrated and compacted every time the casting height is 1 meter;

[0028] After pouring is completed, the cantilever section is subjected to moisture maintenance;

[0029] Carry out pile testing on the entire high cantilever large diameter anti-sliding pile.

[0030] Furthermore, the original ground is excavated at the pile position to form a casing enlargement hole, and a pile connection section casing is arranged in the casing enlargement hole;

[0031] Backfill the original ground with gravel soil not less than 1 meter thick and compact it with large machinery to form a construction working surface, which is flush with the upper end of the pile connection section casing.

[0032] Furthermore, the height ratio of the part of the pile connection section casing below the original ground to the part above the original ground is 1:1; and the secondary casting interface is located at the pile connection section that is higher than the original ground.

[0033] Furthermore, the diameter of the pile connection section casing is 5% to 20% larger than the pile diameter of the underground section.

[0034] Furthermore, a plurality of concave-convex grooves are excavated on the pile head of the pile connection section, the depth or height of the concave-convex grooves is 3-5 cm, and the plurality of concave-convex grooves are evenly distributed on the pile head of the pile connection section.

[0035] Furthermore, the connecting line of the secondary casting interface of the anti-sliding pile wall changes in a wave shape as a whole.

[0036] Furthermore, a conductive fiber mesh is arranged at the secondary pouring interface, and after the secondary pouring, the conductive fiber mesh is energized for heating to accelerate the curing speed and interface strength of the secondary pouring concrete.

[0037] Furthermore, high-strength concrete is used in the secondary casting boundary of the pile connection section and the cantilever section, or fiber reinforcement material or micro-expansion agent is added to the concrete.

[0038] According to a second aspect, a high cantilever large diameter anti-sliding pile is manufactured by the secondary casting pile forming method of the high cantilever large diameter anti-sliding pile.

[0039] According to a third aspect, an anti-sliding pile wall is formed by high cantilever large-diameter anti-sliding piles manufactured by the secondary casting method of the high cantilever large-diameter anti-sliding piles.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] The present invention arranges a casing with a larger pile diameter than that of the underground section in the pile connection section, and forms an enlarged structure of the anti-slip pile through secondary casting, thereby enhancing the strength of the pile connection section and significantly improving the overall stability of the anti-slip pile under complex stress conditions. In addition, by setting the secondary casting interface heights of each anti-slip pile to be staggered, all casting interfaces are prevented from being located in the same horizontal plane, which successfully disperses the stress concentration problem when the anti-slip pile wall is subjected to stress as a whole, thereby reducing the shear risk of the pile body under stress conditions. The overall shear resistance and durability of the anti-slip pile wall are effectively enhanced, making it more suitable for the long-term stable support requirements in high fill slope projects.

[0042] Of course, the implementation of the various technical solutions of the present invention does not necessarily require achieving all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a flow chart of a method according to an embodiment of the present invention;

[0044] Figure 2 A schematic diagram of chiseling a pile head according to an embodiment of the present invention;

[0045] Figure 3 This is a schematic diagram of a pile head reinforcement according to an embodiment of the present invention;

[0046] Figure 4 A schematic diagram of a steel cage for installing a cantilever section according to an embodiment of the present invention;

[0047] Figure 5 A schematic diagram of a template for installing and fixing a cantilever segment according to an embodiment of the present invention; DETAILED DESCRIPTION

[0048] The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present application are not shown or described in the specification, this is to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0049] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0050] Embodiment 1:

[0051] See also Figure 1 The first embodiment of the present invention provides a method for secondary casting of high cantilever large diameter anti-sliding piles, which specifically includes the following steps:

[0052] Step S1: Measurement and Staking

[0053] Step S101: According to the engineering support requirements, the overall direction of the anti-sliding pile wall, the position of each anti-sliding pile, the depth of the underground section, and the spacing between adjacent anti-sliding piles are designed.

[0054] Step S102: setting the secondary casting interface height of each anti-sliding pile to be staggered to avoid all casting interfaces being located on the same horizontal plane, so as to prevent the maximum bending and shearing positions of the pile body from coinciding with the secondary casting interface, and ensure that the overall force of the anti-sliding pile is reasonable.

[0055] In order to optimize the stress-bearing performance of the anti-sliding piles, the height of the secondary casting interface of each anti-sliding pile is staggered to avoid all casting interfaces being located on the same horizontal plane. This design aims to prevent the maximum bending and shear positions of the pile body from coinciding with the secondary casting interface, thereby ensuring the overall rationality of the stress on the anti-sliding piles. In this embodiment, the connecting line of the secondary casting interface of the anti-sliding pile wall presents an overall wave-shaped (sine line) change. Such a wave-shaped design makes the pile body bear the maximum stress at different heights, avoiding the situation where stress is concentrated on the same horizontal plane.

[0056] Step S2: Underground section construction

[0057] Step S201: at the preset pile connection section position, the original ground is excavated to form a casing enlargement hole; the pile connection section casing is placed in the casing enlargement hole. In this embodiment, the diameter of the pile connection section casing is 20 cm larger than the pile diameter of the underground section, and the height ratio of the part below the ground to the part above the ground is 1:1; by setting the casing enlargement hole at the pile connection section position and using the pile connection section casing with a larger diameter, not only sufficient operating space is provided for subsequent pile head processing and secondary pouring, but also an enlarged part structure is formed in the pile connection section after the secondary pouring, thereby enhancing the shear and bending resistance of the pile connection section; the height ratio of the above-ground and underground parts of the casing is 1:1, which ensures the stability and verticality of the casing and facilitates construction operations.

[0058] Step S202: Backfill gravel soil with a thickness of not less than 1 meter, and compact it using large machinery to form a construction working surface; the backfilled construction working surface is flush with the upper end of the pile connection section casing to facilitate subsequent construction.

[0059] Backfill and compact crushed stone soil on the original ground to form a stable construction working surface, providing a solid platform for the operation of large machinery and equipment and construction personnel; the design of the construction working surface being flush with the upper end of the casing of the pile connection section not only protects the casing, but also facilitates subsequent drilling and pouring processes.

[0060] Step S203: After the drilling rig is in place and calibrated, the underground section is drilled. During the construction process, the hole diameter, hole depth and verticality are strictly controlled to ensure that the design requirements are met. After the drilling is completed, the drilling quality is tested.

[0061] Step S204: installing the underground section steel cage in the borehole, with the main reinforcement of the steel cage extending upward to the top of the cantilever section pile to form a full-length main reinforcement, providing conditions for the subsequent connection of the cantilever section steel cage.

[0062] The setting of full-length main reinforcement ensures the continuity and integrity of the steel bars in the underground section and the cantilever section, avoiding structural weak links caused by poor steel bar connections; it provides convenience for the subsequent installation and connection of the cantilever section steel cage, improving the tensile and bending resistance of the pile body; it optimizes the force transfer path of the steel bars and enhances the overall stability of the pile foundation.

[0063] Step S205: lower the guide tube, pour concrete in the underground section and the pile connection section, and complete the first pouring; during pouring, use an appropriate concrete mix ratio to ensure the working performance and strength grade of the concrete.

[0064] Step S3: Pile connection section processing

[0065] Step S301: After the strength of the concrete poured once reaches 50%, the construction working surface is excavated and the casing of the pile connection section is removed.

[0066] Step S302: Chisel away the pile head of the pile connection section that has been poured once until the coarse aggregate of concrete is exposed, and clean up the debris and loose particles on the surface of the pile head to form a rough bonding interface.

[0067] Step S303: a plurality of concave-convex grooves are excavated on the pile head of the connecting pile section, with a depth or height of 3 to 5 cm, and the concave-convex grooves are evenly distributed on the surface of the pile head to enhance the mechanical bite force between the new and old concrete.

[0068] Step S304: implant several reinforcement bars of the same diameter as the main reinforcement of the steel cage at the pile head of the pile connection section; the reinforcement bars are evenly distributed along the periphery with the center of the pile cross section as the base point, and are arranged in a plum blossom shape. The depth of the reinforcement bars is not less than 20 times the diameter of the reinforcement bars, and the spacing is determined according to the design requirements.

[0069] Step S305: roughening the bonding interface and evenly applying a high-strength adhesive to improve the bonding performance between the new and old concrete.

[0070] Step S306: Install the steel cage of the cantilever section, and connect the main reinforcement of the steel cage of the cantilever section with the full-length main reinforcement by mechanical connection such as steel sleeve or welding. Increase the number or diameter of longitudinal steel bars and stirrups in the pile connection section to enhance the steel configuration of the pile connection section.

[0071] The pile head is chiseled off until the coarse aggregate is exposed, and debris is cleared to form a rough bonding interface, which increases the contact area between the new and old concrete and effectively improves the bonding performance of the interface; concave and convex grooves are chiseled and evenly distributed, which not only enhances the mechanical bite force between the new and old concrete, but also improves the shear resistance of the interface.

[0072] In the above steps, the integrity of the pile body and construction safety are ensured by excavating and removing the casing after the concrete strength reaches a certain standard; the pile head is chiseled until the coarse aggregate is exposed, and the debris is cleaned to form a rough bonding interface, which increases the contact area between the new and old concrete and effectively improves the bonding performance of the interface. The concave and convex grooves are chiseled and evenly distributed, which not only enhances the mechanical bite force between the new and old concrete, but also improves the shear resistance of the interface.

[0073] The reinforcement bars are implanted in the connecting pile section with the same diameter as the main reinforcement in a plum blossom shape, ensuring the continuity and reliability of force transfer between the new and old concrete. Combined with the roughening treatment of the interface and the application of high-strength adhesive, the bonding strength of the interface is further enhanced, preventing the formation of cold joints.

[0074] In terms of steel bar connection, mechanical connection or welding methods such as steel sleeves are used to reliably connect the main reinforcement of the cantilever section steel cage with the full-length main reinforcement. Increasing the number or diameter of longitudinal reinforcement and stirrups in the pile connection section strengthens the reinforcement configuration in this area and improves the bending and shear resistance of the pile body. These measures jointly ensure the integrity of the cantilever section and the underground section, and meet the performance requirements of high cantilever large-diameter anti-sliding piles under complex stress conditions.

[0075] In this step S3: the treatment of the pile connection section, a number of technical means such as roughening, cutting concave and convex grooves, planting steel bars, interface treatment and strengthening steel bar configuration are comprehensively used to systematically solve the bonding problem of the secondary pouring interface. Through these refined treatment measures, the bonding strength between the new and old concrete is greatly improved, and the overall structural performance of the pile body is enhanced.

[0076] Step S4: Cantilever section construction steps

[0077] S401: Install and fix the template of the cantilever section; the template is anchored to the pile head of the pile section by bolts. The bolt length is 20 cm. Drill holes around the pile head of the pile section and bury the bolts according to the bolt hole spacing of the steel template.

[0078] Step S402: At 2 / 3 of the full height of the template, three guy ropes are evenly stretched downward at 120°. The guy ropes are at an angle of 45° to the ground, and anchors or weights are set at the fixed ends to ensure the anti-overturning stability and verticality of the template. Figure 5 .

[0079] The combination of bolt anchoring and wind ropes solved the problem of supporting the high cantilever and large diameter pile body formwork, improving construction safety and formwork stability.

[0080] Step S403: pouring cantilever section concrete into the formwork; during pouring, adding an appropriate amount of concrete accelerating agent, the amount of which is determined according to the ambient temperature and construction requirements, so as to control the initial setting time of the concrete, control the pouring speed and add the accelerating agent, effectively preventing the risk of formwork deformation and explosion, and ensuring the construction quality of the concrete.

[0081] Step S404: Control the concrete pouring speed, use a sky pump for pouring, and cooperate with manual vibration. Vibrate and compact once every 1 meter of pouring height to ensure the density of the concrete and prevent quality defects such as honeycombs and holes.

[0082] Step S405: high-strength concrete is used in the pile connection section and the cantilever section, or fiber-reinforced materials or micro-expansion agents are added to the concrete to improve the mechanical properties and crack resistance of the concrete.

[0083] Step S406: After pouring is completed, the cantilever section is subjected to moisture-maintaining maintenance for no less than 7 days to ensure the normal development of concrete strength.

[0084] Step S5: Pile detection

[0085] Step S501: After the concrete strength reaches the design requirement, the high cantilever large diameter anti-sliding pile is tested, including the uniformity, integrity and bearing capacity of the pile concrete.

[0086] Step S502: The anti-slip piles are pre-buried with ultrasonic detection tubes according to a predetermined ratio to perform ultrasonic detection on the pile body; the ultrasonic detection technology can quickly and accurately obtain the internal information of the pile body without destroying the pile body structure. The design of pre-buried ultrasonic detection tubes makes the detection process convenient and efficient, and improves the accuracy and reliability of the detection;

[0087] For piles with abnormal test results, core sampling tests are carried out to obtain real concrete samples for analysis to ensure that the quality of the piles meets the design and specification requirements.

[0088] The above construction method successfully solved the integrity and structural performance problems of high cantilever large diameter anti-sliding piles during the secondary pouring process. The setting of the pile connection section casing and the formation of the enlarged hole make the pile connection section form an enlarged structure, which enhances the shear and bending resistance of the pile connection section. The staggered arrangement of the secondary pouring interface avoids stress concentration and enhances the overall stability of the anti-sliding pile wall.

[0089] In addition, the bonding strength between the new and old concrete and the integrity of the pile body were further improved by setting concave and convex grooves on the pile head of the connecting section, implanting plum blossom-shaped embedded reinforcement, applying high-strength adhesive, and using high-strength concrete and adding fiber-reinforced materials.

[0090] Embodiment 2:

[0091] This embodiment takes a specific high slope treatment project as an example to explain in detail the application of the high cantilever large diameter anti-sliding pile secondary casting method in actual engineering.

[0092] The high fill slope is 190 meters long, the cantilever length of the anti-slide pile is 10 meters, the lower pile diameter is 1.8 meters, the anti-slide pile is 20 meters, there are 37 anti-slide piles in total, and the stratum is floating pebble soil.

[0093] Specific construction steps:

[0094] Step S1: Measurement and Staking

[0095] Step S101: According to the engineering support requirements, the overall direction of the anti-sliding pile wall is designed, and the position of each anti-sliding pile, the underground section depth of 10 meters, and the spacing between adjacent anti-sliding piles are determined.

[0096] Step S102: Set the secondary casting interface height of each anti-sliding pile to be staggered to avoid all casting interfaces being on the same horizontal plane, to prevent the maximum bending and shearing position of the pile body from coinciding with the secondary casting interface, and to ensure the rationality of the overall force of the anti-sliding pile. In this embodiment, the secondary casting interface connection line of the anti-sliding pile row wall changes in a sinusoidal line, and the height difference is set to 0.5 meters.

[0097] Step S2: Underground section construction

[0098] Step S201: At the preset pile connection section position, the original ground is excavated to form a casing enlargement hole; the pile connection section casing is placed in the casing enlargement hole, the casing diameter is 20 cm larger than the pile diameter of 1.8 meters, that is, the casing diameter is 2.0 meters, the casing height is 2.0 meters, and the height ratio of the part below the ground to the part above the ground is 1:1.

[0099] Step S202: Backfill 1 meter thick gravel soil on the original ground and compact it using large machinery to form a construction working surface; the backfilled construction working surface is flush with the upper end of the pile connection section casing to facilitate subsequent construction.

[0100] Step S203: After the drilling rig is in place and calibrated, the underground section is drilled, and the hole depth is 10 meters. During the construction process, the hole diameter, hole depth and verticality are strictly controlled to ensure that the design requirements are met. After the drilling is completed, the drilling quality is tested.

[0101] Step S204: Install the underground section steel cage in the borehole, and the main reinforcement of the steel cage extends upward to the top of the cantilever section pile (cantilever length is 10 meters) to form a full-length main reinforcement, providing conditions for the subsequent connection of the cantilever section steel cage.

[0102] Step S205: lower the pipe, pour concrete in the underground section and the pile connection section, and complete the first pouring. The concrete strength grade is C30, which meets the design requirements.

[0103] Step S3: Pile connection section processing

[0104] Step S301: After the strength of the concrete poured once reaches 50% (about 3-5 days), the construction working surface is excavated and the pile connection section casing is removed.

[0105] Step S302: Chisel off the pile head of the pile connection section that has been poured once until the coarse aggregate of concrete is exposed, and clean up the debris and loose particles on the surface of the pile head to form a rough bonding interface. Figure 2 .

[0106] Step S303: dig concave-convex grooves with a depth of 3-5 cm on the pile head of the pile connection section, evenly distributed on the surface of the pile head, to enhance the mechanical bite force between the new and old concrete.

[0107] Step S304: implant several pile-joint segment embedded bars (e.g., 25 mm in diameter) with the same diameter as the main bars of the steel cage at the pile head of the pile-joint segment. The embedded bars are evenly distributed along the periphery with the center of the pile cross section as the base point, and are arranged in a plum blossom shape. The embedded bar depth is not less than 500 mm, and the spacing is determined according to the design requirements (e.g., 300 mm). See Figure 3 .

[0108] Step S305: roughening the bonding interface and evenly applying high-strength adhesive epoxy resin glue to improve the bonding performance of new and old concrete.

[0109] Step S306: Install the steel cage of the cantilever section, connect the main reinforcement of the steel cage of the cantilever section with the main reinforcement of the full length by mechanical connection or welding; increase the number or diameter of longitudinal reinforcement and stirrups in the pile connection section to enhance the reinforcement configuration of the pile connection section, see Figure 4 .

[0110] Step S307: A conductive fiber mesh is provided at the secondary pouring interface between the pile connection section and the cantilever section; after the secondary pouring is completed, the conductive fiber mesh is electrically heated, and the heating temperature is controlled between 40°C and 60°C, and the power-on time is 24 to 48 hours, which effectively accelerates the curing speed of the concrete and significantly enhances the interface strength between the new and old concrete. The curing speed of the secondary pouring concrete is accelerated and the interface strength is enhanced.

[0111] Step S4: Cantilever segment construction

[0112] Step S401: Install and fix the template of the cantilever section. The template is anchored to the pile head of the connecting pile section through bolts with a length of 20 cm. According to the bolt hole spacing of the steel template, holes are drilled around the pile head to bury the bolts.

[0113] Step S402: At 2 / 3 of the full height of the template, at least three guy ropes are stretched downward at an angle of 120°, with the guy ropes forming a 45° angle with the ground. Anchors or weights are set at the fixed ends to ensure the anti-overturning stability and verticality of the template. Figure 5 .

[0114] Step S403: pouring cantilever section concrete into the formwork, with the concrete strength grade being C35 or higher. During pouring, adding a proper amount of concrete accelerating agent, the amount of which is determined according to the ambient temperature and construction requirements, to control the initial setting time of the concrete.

[0115] Step S404: Control the concrete pouring speed, use a sky pump for pouring, and cooperate with manual vibration. Vibrate and compact the concrete once every 1 meter of pouring height to ensure the density of the concrete and prevent quality defects such as honeycombs and holes.

[0116] Step S405: adding fiber reinforcement material or micro expansion agent into the concrete, wherein the fiber reinforcement material is selected such as polypropylene fiber to improve the mechanical properties and crack resistance of the concrete.

[0117] Step S406: After pouring is completed, the cantilever section is subjected to moisture-curing maintenance for no less than 7 days to ensure normal development of concrete strength.

[0118] Step S5: Pile detection

[0119] Step S501: After the concrete strength reaches the design requirement (generally 28 days after pouring), the high cantilever large diameter anti-sliding piles are tested, and the test content includes the uniformity, integrity and bearing capacity of the pile body concrete.

[0120] Step S502: Pre-embed ultrasonic testing tubes in the anti-sliding piles at a ratio of 100%, and use ultrasonic testing technology to perform non-destructive testing on the pile body. For piles with abnormal test results, core sampling testing is performed to ensure that the quality of the piles meets the design and specification requirements.

[0121] Through the above construction method, 37 high cantilever large diameter anti-sliding piles were successfully constructed, forming an anti-sliding pile wall and ensuring the stability of the slope. The staggered design and optimization of the secondary pouring interface enhanced the integrity and bearing capacity of the pile body. After testing, all indicators met the design and specification requirements and achieved the expected construction effect.

[0122] The method of this embodiment is suitable for the construction of anti-slide piles in high fill slope projects, has the advantages of simple construction process, convenient operation, controllable quality, etc., meets the requirements of engineering design and specifications, and has good promotion and application value.

[0123] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art, according to the concept of the present invention, some simple deductions, modifications or substitutions can be made.

Claims

1. A secondary pouring method for high cantilever large diameter anti-sliding piles, characterized in that: The high cantilever large diameter anti-sliding pile comprises an underground section, a pile connection section and a cantilever section. A plurality of high cantilever large diameter anti-sliding piles are arranged at intervals to form an anti-sliding pile row wall. The pile forming method comprises: (1) Measurement and setting out: According to the support requirements, design the overall direction of the anti-slide pile wall, the position of each anti-slide pile and the depth of the underground section, as well as the spacing between adjacent anti-slide piles; The secondary pouring interfaces of each anti-slide pile are set to be staggered to avoid being on the same horizontal plane; (2) Underground section construction: Backfill gravel soil on the original ground and compact it mechanically to form a construction working surface; Burying a pile connection section casing at a preset pile connection section position of the construction working surface, wherein the pile connection section casing is larger than the pile diameter of the underground section; The drilling rig performs hole-forming construction in the underground section, and after the hole-forming construction is completed, the quality of the hole is tested; The underground section of the steel cage is installed in the hole, and the main reinforcement of the steel cage extends upward to the top of the cantilever section pile to form the full-length main reinforcement; Lower the guide tube, pour the underground section concrete and the pile connection section concrete, and complete the pouring in one go; (3) Pile connection section processing: After the strength of the concrete poured once reaches 50%, the construction working surface is excavated, the pile connection section casing is removed, the pile head of the pile connection section poured once is chiseled off until the coarse aggregate of the concrete is exposed, and the debris on the pile head is cleaned to form a rough bonding interface; Several reinforcement bars with the same diameter as the main reinforcement bars of the reinforcement cage are implanted at the pile head of the pile section. The reinforcement bars are evenly distributed along the periphery with the center of the pile section as the base point, forming a plum blossom shape arrangement; Install the steel cage of the cantilever section, and mechanically connect or weld the main reinforcement of the steel cage of the cantilever section to the through-length main reinforcement; (4) Cantilever section construction: Install and fix the template of the cantilever section, wherein the template is anchored to the pile head of the pile connection section by bolts; At 2 / 3 of the full height of the formwork, tension no less than three guy ropes evenly distributed downward at 120°. The guy ropes should form an angle of 45° with the ground, and ground anchors should be set at the fixed ends. Pour concrete into the formwork and add concrete accelerator; The cantilever section is vibrated and compacted every time the casting height is 1 meter; After pouring is completed, the cantilever section is subjected to moisture maintenance; Carry out pile testing on the entire high cantilever large diameter anti-sliding pile.

2. The secondary pouring pile method of the high cantilever large diameter anti-sliding pile according to claim 1 is characterized in that: Excavate the original ground at the pile position to form a casing enlargement hole, and set the pile connection section casing in the casing enlargement hole; Backfill the original ground with gravel soil not less than 1 meter thick and compact it with large machinery to form a construction working surface, which is flush with the upper end of the pile connection section casing.

3. The secondary pouring pile method of the high cantilever large diameter anti-sliding pile according to claim 2 is characterized in that: The height ratio of the part of the pile connection section casing below the original ground to the part above the original ground is 1:1; the secondary casting interface is located in the pile connection section that is higher than the original ground.

4. The secondary pouring pile method for high cantilever large diameter anti-sliding piles according to claim 1 is characterized in that: The diameter of the pile connection section casing is 5% to 20% larger than the pile diameter of the underground section.

5. The secondary pouring pile method for high cantilever large diameter anti-sliding piles according to claim 1 is characterized in that: A plurality of concave-convex grooves are excavated on the pile head of the pile connection section, the depth or height of the concave-convex grooves is 3-5 cm, and the plurality of concave-convex grooves are evenly distributed on the pile head of the pile connection section.

6. The secondary pouring pile method for high cantilever large diameter anti-sliding piles according to claim 1 is characterized in that: The secondary casting interface connection line of the anti-slide pile wall changes in a wave shape as a whole.

7. The secondary pouring pile method for high cantilever large diameter anti-sliding piles according to claim 1 is characterized in that: A conductive fiber mesh is arranged at the secondary pouring interface, and after the secondary pouring, the conductive fiber mesh is energized for heating to accelerate the curing speed and interface strength of the secondary pouring concrete.

8. The secondary pouring pile method for high cantilever large diameter anti-sliding piles according to claim 1 is characterized in that: High-strength concrete is used in the secondary casting of the pile connection section and the cantilever section, or fiber-reinforced materials or micro-expansion agents are added to the concrete.

9. A high cantilever large diameter anti-slide pile manufactured by the secondary casting pile forming method of the high cantilever large diameter anti-slide pile according to any one of claims 1 to 8.

10. An anti-slide pile wall formed by high cantilever large-diameter anti-slide piles manufactured by the secondary casting pile forming method of high cantilever large-diameter anti-slide piles according to any one of claims 1 to 8.

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