Prestress reinforced slope protection pile and construction method thereof

Abstract

The invention relates to the field of slope protection piles, and discloses a prestress reinforced slope protection pile and a construction method thereof.The slope protection pile comprises a column body, a corrugated pipe is arranged in the column body, an anchor bearing plate is fixedly connected to the outer wall of the corrugated pipe, and the outer wall of the anchor bearing plate is fixedly connected to the interior of the column body; the top end of the anchor backing plate is fixedly connected with an anchoring device, the anchoring device is internally provided with an anchoring device clamping piece, and the inner wall of the anchoring device clamping piece is connected with a steel strand. The construction method comprises the following steps that S1, side slope partitioning and slope protection pile model selection are conducted, a side slope three-dimensional mechanical model is constructed with the help of ANSYS software, and the side slope is partitioned; and slope protection pile types suitable for different areas are determined. The prestressed steel strands are adopted to replace traditional steel bars and are locked, so that the bending strength of the slope protection piles is improved, the overall bearing capacity of the structure is remarkably enhanced, the pile spacing is reasonably selected through accurate numerical simulation analysis, and the cost is reduced while the structure is optimized.

Description

Technical Field

[0001] The invention relates to the technical field of slope protection piles, in particular to prestressed reinforced slope protection piles and a construction method thereof. Background Art

[0002] Slope protection piles are piles set along the side of the foundation pit to prevent slope collapse. They are usually used when the effective width of the slope is not enough. Their function is to prevent the displacement and sinking of the adjacent original engineering foundation, so that the slope of the foundation pit can achieve the maximum slope ratio. Common types of slope protection piles include steel pipe piles, precast concrete piles, bored cast-in-place piles, etc.

[0003] Traditional slope protection pile design usually relies on densely arranged reinforced concrete piles to resist the pressure of slope soil and thus ensure the stability of the slope. This type of slope protection pile has a complex structure, high cost, and a long construction period. At the same time, the stress state of the steel bars used in traditional slope protection piles is limited, making it difficult to fully exert the material properties. Especially in response to large-scale landslides or long-term service conditions, the bearing capacity and economy of slope protection piles need to be improved. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides prestressed reinforced slope protection piles and a construction method thereof, which solve the problems that traditional slope protection piles rely on densely arranged reinforced concrete piles to resist the pressure of slope soil, have complex structures, high costs, long construction periods, limited stress states of steel bars, and are difficult to fully exert material properties. The bearing capacity and economy of the slope protection piles need to be improved.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: prestressed reinforced slope protection piles, including a column, a corrugated tube is arranged inside the column, the outer wall of the corrugated tube is fixedly connected to an anchor plate, the outer wall of the anchor plate is fixedly connected to the inside of the column, the top of the anchor plate is fixedly connected to an anchor, an anchor clip is arranged inside the anchor, and the inner wall of the anchor clip is connected to a steel strand.

[0006] The present invention also provides a construction method of prestressed reinforced slope protection piles, comprising the following steps: S1. Slope zoning and slope protection pile selection. Use ANSYS software to build a three-dimensional slope mechanical model to divide the slope and determine the type of slope protection piles suitable for different areas; S2. Select the pile spacing according to the stress conditions and determine the slope protection pile spacing according to the lateral force on the slope protection piles. Different lateral force value ranges correspond to different slope protection pile spacings. S3, hole construction, adjust the drilling rig speed and drilling speed according to different soil types, prepare the wall protection mud, control the steel casing parameters, bottom sediment, hole diameter and verticality deviation; S4. Fabrication and installation of steel strand bundles and steel cages. Fabricate steel strand bundles and steel cages, control the tensile stress and cutting length of steel strands, determine the specifications of steel cage steel bars, cutting and welding errors, accurately install anchors and corrugated pipes, insert and straighten steel strand bundles; S5. Prestressed graded tensioning and locking. Use calibrated jacks for tensioning, load according to the designed stress grades, control the loading rate and holding time, use sensors to monitor the elongation of the steel strands, lock the anchor rods as required, cut off the excess steel strands and seal the anchors for corrosion protection.

[0007] Preferably, in step S1, the finite element analysis software ANSYS is used to model and analyze the slope, and a three-dimensional mechanical model of the slope is established. The model parameters include elastic modulus, Poisson's ratio, internal friction angle, cohesion, and interaction between the slope protection piles and the soil. The lateral force per square meter of soil is used as a measurement indicator. Through simulation analysis, it is determined that prestressed reinforced slope protection piles are set in areas where the lateral force is greater than 50kN / m², and ordinary concrete piles are used in areas where the lateral force is less than 30kN / m².

[0008] Preferably, in step S2, when the lateral force on the slope protection piles is below 30 kN / m², the pile spacing is controlled at 2.5 to 3.0 m; when the lateral force is between 30 and 50 kN / m², the pile spacing is set to 1.8 to 2.5 m; when the lateral force is greater than 50 kN / m², the pile spacing is reduced to 1.2 to 1.8 m.

[0009] In the step S3, a rotary drilling rig is used to drill a hole, wherein in clay soil, the rotary drilling rig has a rotation speed of 10 to 20 r / min and a drilling speed of 0.5 to 1.0 m / min, and in sandy soil, the rotation speed is 8 to 15 r / min and a drilling speed of 0.3 to 0.8 m / min.

[0010] Preferably, in the S3 step, the wall protection mud has a relative density of 1.05-1.20, a viscosity of 18-22s, a sand content of not more than 4%, a colloid rate of not less than 95%, a water loss rate of not more than 30mL / 30min, a pH value of 8-10, an inner diameter of the steel casing 10-20cm larger than the designed aperture, a top elevation of 0.3m above the ground, a thickness of the sediment at the bottom of the hole not exceeding 50mm, an aperture deviation controlled within ±50mm, and a verticality deviation of less than 1%.

[0011] Preferably, in step S4, the steel strand bundle adopts a single bundle of unbonded steel strands and the tensioning control stress is 0.65-0.75fptk, the main reinforcement of the steel cage adopts HRB400 grade steel bars with a diameter of 20-25mm and a protective layer thickness of ≥50mm, the error of the steel bar cutting length is controlled within ±10mm, the steel cage welding diameter deviation is controlled within ±10mm, and the length deviation is controlled within ±50mm. The steel strands are bundled into 7 bundles, and centering brackets are set at intervals of 1.5-2.0m. The error of the steel strand cutting length is controlled within ±50mm.

[0012] Preferably, in step S4, when the anchor plate is installed, the deviation between its center and the center of the hole does not exceed ±5mm, the deviation of the installation position of the anchor does not exceed ±5mm, the spacing between the fixing points of the corrugated pipe is not greater than 1m, the steel strand bundle is inserted into the corrugated pipe, and the exposed length at both ends is ≥800mm, and a comb plate is used to straighten it to avoid cross-entanglement.

[0013] Preferably, in the step S5, a jack is used for prestressing, the axis of the jack coincides with the center line of the hole, the deviation is ≤1°, the jack and the pressure gauge are calibrated, the tensioning force is controlled according to σcon=0.75fptk, and graded tensioning is performed. The tensioning process follows the principle of "graded loading, slow and uniform speed", and the design stress is loaded in stages at 20% to 50% to 100%, with each stage holding the load for 5 minutes, and the loading rate is not more than 0.1 times the standard value of the anchor axial tension / min.

[0014] Preferably, in the step S5, a fiber grating displacement sensor is used to measure the elongation of the steel strand, and the error between the actual elongation value and the theoretical elongation value is controlled within ±6%. The anchor locking value is 0.75 to 0.9 times the standard value of the anchor axial tension. When locked, the anchor tension is 1.1 to 1.15 times the locking value. After locking, the excess steel strand is cut off, and the exposed end length does not exceed 30 mm. C30 fine stone concrete is used to seal the anchor and anti-corrosion asphalt is applied externally.

[0015] The present invention provides a prestressed reinforced slope protection pile and a construction method thereof, which has the following beneficial effects: 1. The present invention replaces traditional steel bars with prestressed steel strands and locks them, thereby improving the bending strength of slope protection piles and significantly enhancing the overall bearing capacity of the structure. Accurate numerical simulation analysis is used to reasonably select the pile spacing, thereby optimizing the structure and reducing costs.

[0016] 2. The present invention uses a fiber grating displacement sensor to measure the elongation value of the steel strand during the prestressed graded tensioning process, so that the control of the prestress value is more accurate and reliable, the construction quality is fundamentally improved, and the cost and risk of future maintenance are reduced.

[0017] 3. The present invention accurately understands the stress conditions of different areas of the slope, selects appropriate types of slope protection piles in a targeted manner, and forms a composite pile foundation layout strategy, which can not only meet engineering requirements, but also avoid over-design, save costs, and improve the safety and reliability of the entire slope support system, taking into account both safety and economic needs and optimizing resource allocation.

[0018] 4. The present invention strictly controls the tension stress, loading rate, holding time and elongation value error, standardizes the construction process, reduces construction errors and uncertainties, ensures accurate application of prestress, and improves construction quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A three-dimensional diagram of the prestressed reinforced slope protection pile proposed by the present invention; Figure 2 It is a schematic diagram of the partial structure of the anchoring device of the prestressed reinforced slope protection pile proposed in the present invention; Figure 3 A schematic cross-sectional view of the internal structure of the column of the prestressed reinforced slope protection pile proposed in the present invention; Figure 4 This is a flow chart of the construction method of the prestressed reinforced slope protection piles proposed in the present invention.

[0020] Among them, 1. Column; 2. Corrugated pipe; 3. Anchor plate; 4. Anchoring anchor; 5. Anchor clip; 6. Steel strand. DETAILED DESCRIPTION

[0021] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Please refer to the attached Figure 1 - Attachment Figure 3 An embodiment of the present invention provides a prestressed reinforced slope protection pile, including a column 1, a corrugated tube 2 is arranged inside the column 1, an anchor plate 3 is fixedly connected to the outer wall of the corrugated tube 2, the outer wall of the anchor plate 3 is fixedly connected to the inside of the column 1, an anchor 4 is fixedly connected to the top of the anchor plate 3, an anchor clip 5 is arranged inside the anchor 4, and a steel strand 6 is connected to the inner wall of the anchor clip 5.

[0023] Specifically, the column 1 is the main structure of the prestressed reinforced slope protection pile, which directly bears the lateral pressure from the soil. It transfers the prestress applied by the steel strand 6 to the soil, interacts with the soil, resists the sliding and deformation tendency of the soil, and maintains the stability of the slope.

[0024] The corrugated tube 2 is used to protect the steel strand 6 to prevent the steel strand 6 from being damaged during the construction process, and also provides a channel for applying prestress.

[0025] The anchor plate 3 is an important part connecting the anchoring anchor 4 and the column 1, and plays a role in dispersing stress. During the prestressing process, the anchor plate 3 evenly disperses the huge concentrated force transmitted by the steel strand 6 to the concrete of the column 1, avoiding the concrete from being damaged due to excessive local stress.

[0026] The anchoring device 4 is used to fix the end of the steel strand 6 and reliably transmit the tension of the steel strand 6 to the column 1. After the prestressing is completed, the anchoring device 4 tightly clamps the steel strand 6 to keep a certain tension of the steel strand 6, thereby providing prestressing for the slope protection pile.

[0027] The anchor clip 5 is an important component of the anchor 4. It is used in conjunction with the anchor 4 to tightly grip the steel strand 6, ensuring that the tension of the steel strand 6 can be stably transmitted to the slope protection pile column 1 to prevent the steel strand 6 from loosening or sliding.

[0028] The steel strand 6 is the core material for applying prestress to the prestressed reinforced slope protection pile. By tensioning the steel strand 6, it produces elastic deformation, thereby providing prestress for the slope protection pile. Under the lateral pressure of the soil, the prestress of the steel strand 6 can offset part of the tension, improve the bending and shear resistance of the slope protection pile, and reduce the deformation of the pile body.

[0029] Please refer to the attached Figure 4 The construction method of the prestressed reinforced slope protection pile comprises the following steps: S1. Slope zoning and slope protection pile selection. Use ANSYS software to build a three-dimensional slope mechanical model to divide the slope and determine the type of slope protection piles suitable for different areas; S2. Select the pile spacing according to the stress conditions and determine the slope protection pile spacing according to the lateral force on the slope protection piles. Different lateral force value ranges correspond to different slope protection pile spacings. S3, hole construction, adjust the drilling rig speed and drilling speed according to different soil types, prepare the wall protection mud, control the steel casing parameters, bottom sediment, hole diameter and verticality deviation; S4, production and installation of 6 bundles of steel strands and steel cages, production of 6 bundles of steel strands and steel cages, control of tensile stress and cutting length of steel strands 6, determination of specifications of steel cage steel bars, cutting and welding errors, precise installation of anchoring devices and corrugated pipes 2, insertion and straightening of 6 bundles of steel strands; S5. Prestressed graded tensioning and locking. Use calibrated jacks for tensioning, load according to designed stress grades, control loading rate and load holding time, use sensors to monitor the elongation value of steel strand 6, lock anchor rods according to regulations, cut off excess steel strand 6 and seal anchors for corrosion protection.

[0030] Specifically, this construction method improves the quality, efficiency and safety of slope protection pile construction in all aspects through a series of scientific and innovative technical means, while achieving effective cost control. The three-dimensional mechanical model analysis of the slope is carried out with the help of ANSYS software to select the zoning plan, which enhances the reliability of the slope support system and reduces unnecessary materials and construction investment. The pile spacing is selected according to the lateral force on the slope protection pile, which ensures the support capacity while avoiding resource waste and reducing construction costs.

[0031] During the drilling construction, the drilling rig speed and drilling speed were adjusted according to different soil types, and the performance of the wall mud, steel casing parameters, bottom sediment, hole diameter and verticality deviation were strictly controlled to ensure the quality of the hole, lay a solid foundation for subsequent processes, improve the bearing capacity of the slope protection pile, reduce the risk of rework caused by hole quality problems, and improve construction efficiency. In the process of making and installing the 6 strands of steel strands and the steel cage, various parameters were accurately controlled, and the anchoring anchor 4 and the corrugated pipe 2 were accurately installed to ensure the effective transmission of prestress, enhance the deformation resistance of the slope protection pile, and thus improve the quality of the entire project.

[0032] During the prestressed graded tensioning and locking process, with the help of calibrated equipment, the tensioning stress and loading rate are strictly controlled, the elongation value of the steel strand 6 is monitored in real time and locked according to regulations, so that the steel strand 6 can maintain the prestress stably, effectively improving the bearing and deformation resistance of the slope protection piles and ensuring the stability of the slope.

[0033] In step S1, the finite element analysis software ANSYS is used to model and analyze the slope and establish a three-dimensional mechanical model of the slope. The model parameters include elastic modulus, Poisson's ratio, internal friction angle, cohesion, and the interaction between the slope protection piles and the soil. The lateral force per square meter of soil is used as the measurement indicator. Through simulation analysis, it is determined that prestressed reinforced slope protection piles are set in areas where the lateral force is greater than 50kN / m², and ordinary concrete piles are used in areas where the lateral force is less than 30kN / m².

[0034] Specifically, data collection: obtain geological survey reports, collect information such as soil parameters such as elastic modulus, groundwater level and surrounding loads.

[0035] Model construction: In ANSYS software, a three-dimensional slope model is established according to the actual terrain and soil layer distribution, parameters of each soil layer are assigned, and pile-soil interaction is set.

[0036] Condition setting: Determine the model boundary conditions and apply loads such as soil self-weight and ground overload.

[0037] Simulation calculation: run the program to calculate slope stress and strain, paying attention to the lateral force of the soil.

[0038] Pile type zoning: Based on the lateral force, prestressed reinforced piles are used in areas above 50kN / m², ordinary concrete piles are used in areas below 30kN / m², and the pile type is determined by evaluation in the area between 30 and 50kN / m².

[0039] Beneficial effects: Through precise numerical simulation analysis, we can accurately understand the stress conditions in different areas of the slope and select the appropriate type of slope protection piles in a targeted manner. Prestressed reinforced slope protection piles are set up in areas with large lateral forces to give full play to their high strength and high prestress characteristics, effectively resist the lateral pressure of the soil, and enhance the stability of the slope; ordinary concrete piles are used in areas with small lateral forces, which can not only meet engineering requirements, but also avoid over-design and save costs. This zoning planning design method improves the safety and reliability of the entire slope support system.

[0040] In step S2, when the lateral force on the slope protection piles is below 30kN / m², the pile spacing is controlled at 2.5-3.0m; when the lateral force is between 30-50kN / m², the pile spacing is set to 1.8-2.5m; when the lateral force is greater than 50kN / m², the pile spacing is reduced to 1.2-1.8m.

[0041] Specifically, the lateral force data is obtained: the lateral force data of each slope protection pile position is extracted from the finite element analysis result of step S1.

[0042] Select the pile spacing: Determine the slope protection pile spacing based on the lateral force. When the lateral force is less than 30kN / m², select between 2.5 and 3.0m; when it is 30 to 50kN / m², select between 1.8 and 2.5m; when it is greater than 50kN / m², determine the spacing between 1.2 and 1.8m, and make fine adjustments considering factors such as deformation control and construction conditions.

[0043] Beneficial effects: By reasonably selecting the pile spacing according to the size of the lateral force, the organic unity of structural design optimization and cost control is achieved. In terms of structural design, different lateral force areas are matched with appropriate pile spacing, so that the layout of slope protection piles is scientific and reasonable. Large pile spacing is used in small lateral force areas to avoid waste of resources, and the pile spacing is reduced in large lateral force areas to ensure support capacity, thereby improving the overall performance and reliability of the slope support structure. In terms of cost control, accurate pile spacing selection avoids unnecessary pile foundation construction, reduces the amount of building materials, construction workload, and manpower and machinery costs, and maximizes economic benefits on the basis of ensuring project safety. This force-based pile spacing design method reduces costs while optimizing the structure, bringing significant comprehensive benefit improvements to slope protection pile projects.

[0044] In step S3, a rotary drilling rig is used to drill a hole. In clay soil, the rotary drilling rig has a rotation speed of 10 to 20 r / min and a drilling speed of 0.5 to 1.0 m / min. In sandy soil, the rotation speed is 8 to 15 r / min and a drilling speed of 0.3 to 0.8 m / min.

[0045] In step S3, the relative density of the wall protection mud is 1.05-1.20, the viscosity is 18-22s, the sand content is not more than 4%, the colloid rate is not less than 95%, the water loss rate is not more than 30mL / 30min, the pH value is 8-10, the inner diameter of the steel casing is 10-20cm larger than the designed aperture, the top mark is 0.3m above the ground, the thickness of the sediment at the bottom of the hole does not exceed 50mm, the aperture deviation is controlled within ±50mm, and the verticality deviation is less than 1%.

[0046] Specific preparation work: check geological report, understand soil distribution, debug rotary drilling rig, prepare mud materials, mixing equipment and testing instruments.

[0047] Drilling operation: adjust parameters according to soil quality. In clay soil, the drilling rig speed is 10-20r / min, and the speed is 0.5-1.0m / min. In sandy soil, the speed is 8-15r / min, and the speed is 0.3-0.8m / min. Pay attention to the condition of the drilling rig during the process.

[0048] Mud management: Prepare wall protection mud according to indicators, control relative density, viscosity, etc., add mud during drilling, test performance regularly, and make adjustments if it is not in compliance.

[0049] Steel casing installation: select suitable steel casing with an inner diameter 10 to 20 cm larger than the hole diameter. After checking the quality, hang it vertically and fix it so that the top is 0.3 m above the ground.

[0050] Quality control: After drilling to the required depth, measure the sediment at the bottom of the hole. If it exceeds 50mm, clean the hole. Use instruments to measure the hole diameter and verticality. If it does not meet the requirements, handle it.

[0051] Beneficial effects: Adjust parameters according to soil quality, control mud performance, prevent hole collapse and shrinkage, stabilize hole wall, and lay the foundation for subsequent processes. Accurately control various indicators to ensure that pile size and position meet standards, improve pile-soil friction and pile body stress performance. Targeted at construction of different soil types, adapt to complex geology, and ensure that slope protection pile engineering is reliable and stable.

[0052] In step S4, 6 bundles of unbonded steel strands are used, and the stress of a single bundle of 6 strands is controlled to be 0.65-0.75fptk. The main reinforcement of the steel cage is HRB400 grade steel with a diameter of 20-25mm and a protective layer thickness of ≥50mm. The error of the steel bar cutting length is controlled within ±10mm, the steel cage welding diameter deviation is controlled within ±10mm, and the length deviation is controlled within ±50mm. 67 steel strands are bundled, and centering brackets are set at intervals of 1.5-2.0m. The error of the cutting length of the steel strand 6 is controlled within ±50mm.

[0053] In step S4, when the anchor plate 3 is installed, the deviation between its center and the center of the channel shall not exceed ±5mm, the installation position deviation of the anchor 4 shall not exceed ±5mm, the spacing between the fixed points of the corrugated pipe 2 shall not be greater than 1m, and the 6 bundles of steel strands shall be inserted into the corrugated pipe 2 with the exposed length of both ends ≥800mm. A comb plate shall be used to straighten them to avoid cross-entanglement.

[0054] Specifically, material preparation: according to the design requirements, purchase unbonded steel strands 6, HRB400 grade steel bars, anchor plates 3, anchoring anchors 4, corrugated pipes 2 and other materials, and inspect the quality.

[0055] Production of 6 bundles of steel strands: 7 steel strands are designed to be bundled into 6 bundles, cut with a grinding wheel saw, and the cutting length error is controlled within ±50mm. Centering brackets are installed every 1.5 to 2.0m.

[0056] Steel cage production: According to the design, the main reinforcement diameter is determined to be 20-25mm, and the steel bars are cut to control the cutting length error within ±10mm. After the steel cage is welded, the welding diameter deviation is controlled within ±10mm, the length deviation is within ±50mm, and the protective layer thickness is guaranteed to be ≥50mm.

[0057] Component installation: Install anchor pad 3 and anchor 4, ensuring that the deviation between their center and the hole center does not exceed ±5mm. Fix the corrugated pipe 2 at a spacing of no more than 1m. Insert 6 bundles of steel strands into the corrugated pipe 2, with the exposed length of both ends ≥800mm, and straighten them with a comb plate.

[0058] Overall inspection: After the installation is completed, comprehensively check the installation status of each component to ensure that it meets the requirements of various data indicators.

[0059] Beneficial effects: Precisely control the manufacturing and installation parameters of the steel strand 6 bundles and the steel cage, so that the structure can effectively withstand external forces. Reasonable tensile stress of the steel strand 6 and correct steel cage specifications ensure that the slope protection pile has sufficient bearing, shear and crack resistance to meet the stability requirements of the project. Accurate installation of anchor pads 3, anchoring anchors 4 and corrugated pipes 2, as well as straightening of the steel strand 6 bundles, ensure that the prestress can be smoothly transferred from the steel strand 6 to the slope protection pile structure, enhance the deformation resistance of the slope protection pile, and improve the overall quality of the project.

[0060] In step S5, a jack is used for prestressing. The axis of the jack coincides with the center line of the hole, with a deviation of ≤1°. The jack and the pressure gauge are calibrated together, and the tensioning force is controlled according to σcon=0.75fptk. Gradual tensioning is carried out. The tensioning process follows the principle of "gradual loading, slow and uniform speed". The design stress is loaded in stages at 20%~50%~100%, and each stage is held for 5 minutes. The loading rate is not more than 0.1 times the standard value of the anchor axial tension / min.

[0061] In step S5, a fiber grating displacement sensor is used to measure the elongation value of the steel strand 6. The error between the actual elongation value and the theoretical elongation value is controlled within ±6%. The anchor locking value is 0.75 to 0.9 times the standard value of the anchor axial tension. When locked, the anchor tension is 1.1 to 1.15 times the locking value. After locking, the excess steel strand 6 is cut off, and the exposed end length does not exceed 30 mm. C30 fine stone concrete is used to seal the anchor and anti-corrosion asphalt is applied on the outside.

[0062] Specifically, equipment preparation and calibration: select an appropriate jack and send it to a professional organization for calibration together with a pressure gauge to obtain calibration data to ensure accuracy. During installation, adjust the position of the jack so that the deviation between the jack axis and the center line of the channel is ≤1°.

[0063] Tensioning operation: according to the tensioning force σcon = 0.75fptk, follow the principle of "graded loading, slow and uniform speed", load in stages according to 20% ~ 50% ~ 100% of the design stress, the loading rate of each stage shall not exceed 0.1 times the standard value of the axial tension of the anchor rod / min, and each stage shall be held for 5 minutes.

[0064] Elongation value monitoring: Install a fiber grating displacement sensor to measure the elongation value of the steel strand in real time and compare it with the theoretical value. If the error exceeds ±6%, suspend the tensioning and check the equipment, steel strand 6 and calculation parameters, and continue after adjustment.

[0065] Locking and subsequent treatment: After reaching the design stress, the locking value is determined according to 0.75 to 0.9 times the standard value of the anchor rod axial tension, and the tension during locking is 1.1 to 1.15 times the locking value. After the locking is completed, the excess steel strand 6 is cut off with hydraulic equipment so that the exposed end length does not exceed 30mm, and then the anchor is sealed with C30 fine stone concrete, and finally anti-corrosion asphalt is applied on the surface of the anchor sealing concrete.

[0066] Beneficial effects: Gradual tensioning and locking enable the steel strand 6 to maintain prestress stably, improve the bearing capacity and deformation resistance of the slope protection pile, effectively resist the lateral force of the soil, ensure the stability of the slope, and meet the stability requirements of the project. Strictly control the tension stress, loading rate, holding time and elongation value error, standardize the construction process, reduce construction errors and uncertainties, ensure accurate application of prestress, and improve construction quality. After locking, cut off the excess steel strand 6 and perform anchor sealing and anti-corrosion treatment to prevent the steel strand 6 from rusting, protect the anchor end of the anchor rod, extend the service life of the slope protection pile, reduce the later maintenance cost, and improve the durability of the project.

[0067] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Prestressed reinforced slope protection pile, characterized in that: The invention comprises a column (1), wherein a corrugated tube (2) is arranged inside the column (1), an anchor plate (3) is fixedly connected to the outer wall of the corrugated tube (2), the outer wall of the anchor plate (3) is fixedly connected to the inside of the column (1), an anchoring device (4) is fixedly connected to the top end of the anchor plate (3), an anchoring device clip (5) is arranged inside the anchoring device (4), and a steel strand (6) is connected to the inner wall of the anchoring device clip (5).

2. The construction method of the prestressed reinforced slope protection pile according to claim 1 is characterized in that: The following steps are involved: S1. Slope zoning and slope protection pile selection. Use ANSYS software to build a three-dimensional slope mechanical model to divide the slope and determine the type of slope protection piles suitable for different areas; S2. Select the pile spacing according to the stress conditions and determine the slope protection pile spacing according to the lateral force on the slope protection piles. Different lateral force value ranges correspond to different slope protection pile spacings. S3, hole construction, adjust the drilling rig speed and drilling speed according to different soil types, prepare the wall protection mud, control the steel casing parameters, bottom sediment, hole diameter and verticality deviation; S4, manufacturing and installing the steel strand (6) bundle and the steel cage, manufacturing the steel strand (6) bundle and the steel cage, controlling the tensile stress and cutting length of the steel strand (6), determining the steel cage steel bar specifications, cutting and welding errors, accurately installing the anchoring anchor and the corrugated pipe (2), inserting and straightening the steel strand (6) bundle; S5. Prestressing graded tensioning and locking: Use a calibrated jack to tension, load according to the designed stress graded load, control the loading rate and load holding time, use sensors to monitor the elongation value of the steel strand (6), lock the anchor rod according to regulations, cut off the excess steel strand (6) and seal the anchor for corrosion protection.

3. The construction method of the prestressed reinforced slope protection pile according to claim 2 is characterized in that: In the step S1, the finite element analysis software ANSYS is used to model and analyze the slope, and a three-dimensional mechanical model of the slope is established. The model parameters include elastic modulus, Poisson's ratio, internal friction angle, cohesion, and the interaction between the slope protection piles and the soil. The lateral force per square meter of soil is used as a measurement indicator. Through simulation analysis, it is determined that prestressed reinforced slope protection piles are set in areas where the lateral force is greater than 50kN / m², and ordinary concrete piles are used in areas where the lateral force is less than 30kN / m².

4. The construction method of the prestressed reinforced slope protection pile according to claim 2 is characterized in that: In the step S2, when the lateral force on the slope protection piles is below 30 kN / m², the pile spacing is controlled at 2.5 to 3.0 m; when the lateral force is between 30 and 50 kN / m², the pile spacing is set to 1.8 to 2.5 m; when the lateral force is greater than 50 kN / m², the pile spacing is reduced to 1.2 to 1.8 m.

5. The construction method of the prestressed reinforced slope protection pile according to claim 2 is characterized in that: In the step S3, a rotary drilling rig is used to drill a hole, wherein in clay soil, the rotary drilling rig has a rotation speed of 10 to 20 r / min and a drilling speed of 0.5 to 1.0 m / min, and in sandy soil, the rotation speed is 8 to 15 r / min and a drilling speed of 0.3 to 0.8 m / min.

6. The construction method of the prestressed reinforced slope protection pile according to claim 2 is characterized in that: In the step S3, the relative density of the wall protection mud is 1.05-1.20, the viscosity is 18-22s, the sand content is not more than 4%, the colloid rate is not less than 95%, the water loss rate is not more than 30mL / 30min, the pH value is 8-10, the inner diameter of the steel casing is 10-20cm larger than the designed aperture, the top mark is 0.3m above the ground, the thickness of the sediment at the bottom of the hole does not exceed 50mm, the aperture deviation is controlled within ±50mm, and the verticality deviation is less than 1%.

7. The construction method of the prestressed reinforced slope protection pile according to claim 2 is characterized in that: In step S4, the steel strand (6) bundle adopts unbonded steel strand (6) and the tension control stress of a single bundle is 0.65-0.75fptk. The main reinforcement of the steel cage adopts HRB400 grade steel bars with a diameter of 20-25mm and a protective layer thickness of ≥50mm. The error of the steel bar cutting length is controlled within ±10mm, the steel cage welding diameter deviation is controlled within ±10mm, and the length deviation is controlled within ±50mm. The steel strand (6) is bundled with 7 strands, and centering brackets are set at intervals of 1.5-2.0m. The error of the steel strand (6) cutting length is controlled within ±50mm.

8. The construction method of the prestressed reinforced slope protection pile according to claim 2 is characterized in that: In the step S4, when the anchor plate (3) is installed, the deviation between its center and the center of the hole does not exceed ±5 mm, the installation position deviation of the anchor (4) does not exceed ±5 mm, the spacing between the fixing points of the corrugated pipe (2) is not greater than 1 m, the steel strand (6) bundle is inserted into the corrugated pipe (2), the exposed length of both ends is ≥ 800 mm, and a comb plate is used to straighten it to avoid cross winding.

9. The construction method of the prestressed reinforced slope protection pile according to claim 2 is characterized in that: In the step S5, a jack is used for prestressing, the axis of the jack coincides with the center line of the hole, the deviation is ≤1°, the jack is calibrated with the pressure gauge, the tensioning force is controlled according to σcon=0.75fptk, and graded tensioning is performed. The tensioning process follows the principle of "graded loading, slow and uniform speed", and the design stress is loaded in stages at 20% to 50% to 100%, and each stage is held for 5 minutes. The loading rate is not more than 0.1 times the standard value of the anchor axial tension / min.

10. The construction method of the prestressed reinforced slope protection pile according to claim 2, characterized in that: In the step S5, a fiber Bragg grating displacement sensor is used to measure the elongation value of the steel strand (6), and the error between the actual elongation value and the theoretical elongation value is controlled within ±6%. The anchor locking value is 0.75 to 0.9 times the standard value of the anchor axial tension. When locked, the anchor tension is 1.1 to 1.15 times the locking value. After locking, the excess steel strand (6) is cut off, and the exposed end length does not exceed 30 mm. C30 fine stone concrete is used to seal the anchor and anti-corrosion asphalt is applied externally.

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