A gradient grouting reinforcement test device and method in an eroding foundation environment

Abstract

The present application belongs to the technical field of pile foundation in geotechnical engineering, and proposes a gradient grouting reinforcement test device and method in a corrosive foundation environment. The gradient grouting mechanism includes a grouting circular inner tube, a grouting circular outer tube sleeved outside the grouting circular inner tube, and a plurality of grouting circular inclined pipes arranged on the grouting circular outer tube. A gap is left between the grouting circular inner tube and the grouting circular outer tube. The gradient grouting mechanism realizes gradient precise grouting at different depths through the rotational movement of the grouting inner tube. The steel electrochemical accelerated corrosion system can simulate the marine corrosion environment and the land corrosive foundation, realize the accelerated corrosion of the pile foundation, and on this basis, reinforce the pile body through the gradient grouting method. The actual corrosive foundation environment can be accurately simulated, and effective test means and scientific basis are provided for the repair and reinforcement of the pile foundation in the corrosive environment.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering pile foundation technology, and particularly relates to a gradient grouting reinforcement test device and method in a corrosive foundation environment. Background Technology

[0002] In corrosive foundation environments such as coastal areas, saline soil areas, and industrial pollution areas, the foundation soil and groundwater contain abundant corrosive ions such as sulfates and chlorides. These corrosive ions can cause long-term chemical corrosion to concrete piles and steel pipe piles, leading to a reduction in pile strength and seriously affecting the bearing capacity and durability of the pile foundation, thus posing a serious threat to the safety of the superstructure.

[0003] For existing pile foundations in corrosive soil environments, traditional reinforcement methods often employ techniques such as pile perimeter grouting. This involves injecting cement-based or chemical grout into the pile-soil interface to form a reinforcing ring, thereby increasing pile side friction and end resistance. However, conventional uniform grouting methods struggle to differentiate reinforcement based on the degree of corrosion damage at different pile depths. Grouting material utilization is low, resulting in a one-size-fits-all reinforcement effect and poor economic efficiency. Furthermore, current technologies lack the ability to accurately simulate actual corrosive soil environments, leaving reinforcement scheme designs without sufficient experimental data support, leading to a degree of experiential and arbitrary application. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a gradient grouting reinforcement test device and method for corrosive foundation environments. The gradient grouting mechanism achieves precise gradient grouting at different depths through the rotational movement of the grouting inner tube. The electrochemical accelerated corrosion system for steel bars can simulate marine corrosion environments and terrestrial corrosive foundations, achieving accelerated corrosion of pile foundations. Based on this, the pile body is reinforced through gradient grouting, which can accurately simulate the actual corrosive foundation environment and provide an effective test method and scientific basis for the repair and reinforcement of pile foundations under corrosive environments.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a gradient grouting reinforcement test device for corrosive foundation environments, employing the following technical solution: A gradient grouting reinforcement test device in a corrosive foundation environment includes a model box, and a precast concrete pile, a gradient grouting mechanism, and a steel reinforcement electrochemical accelerated corrosion system disposed in the model box; The gradient grouting mechanism includes a grouting circular inner tube, a grouting circular outer tube sleeved outside the grouting circular inner tube, and multiple grouting circular inclined tubes disposed on the grouting circular outer tube; a gap is left between the grouting circular inner tube and the grouting circular outer tube, and gradient grouting at different depths is achieved by rotating the grouting circular inner tube.

[0006] Furthermore, the model box 11 is provided with a drain hole at the bottom and a water inlet on the side, and the water inlet is connected to a water pump.

[0007] Furthermore, the foundation soil layers are laid in layers inside the model box, and the maximum and minimum dry densities of the foundation soil are measured. ρ d，max ρ d，min ， The elevation for each filling is set as follows: h i According to the net length of the model box a Net width b and the set foundation soil compaction degree D r The mass of the foundation soil in each layer was obtained. m i : .

[0008] Furthermore, the precast concrete pile includes multiple longitudinal bars, which are connected to the pile perimeter ring at different heights.

[0009] Furthermore, the steel bar electrochemical accelerated corrosion system includes a power source and a steel mesh connected to one end of the power source via a conductor; the other end of the power source is connected to the precast concrete pile via a conductor.

[0010] Furthermore, the positive terminal of the power supply is connected to the longitudinal reinforcement of the precast concrete pile via a wire; the negative terminal of the power supply is connected to the steel mesh via a wire, and graphite is disposed on the steel mesh.

[0011] Furthermore, there are multiple gradient grouting mechanisms, which are evenly arranged at a preset angle around the precast concrete pile.

[0012] Furthermore, the precast concrete pile is provided with a first longitudinal bar, a second longitudinal bar, and a third longitudinal bar, which are connected to the pile perimeter ring plate at different elevation positions through the first transverse section steel bar, the second transverse section steel bar, and the third transverse section steel bar.

[0013] Furthermore, the bottom of the grouting circular inner tube is connected to a circular rotating support, the top of the circular rotating support is connected to the bottom of the grouting circular inner tube, and the bottom of the circular rotating support is connected to the top of the grouting circular outer tube; the grouting circular outer tube has an embedded annular rotating shaft in contact with the grouting circular inner tube, and the grouting circular inner tube has curved square holes at multiple locations, with the multiple curved square holes located at three preset elevations.

[0014] To achieve the above objectives, in a second aspect, the present invention also provides a method for gradient grouting reinforcement testing in corrosive foundation environments, employing the following technical solution: A gradient grouting reinforcement test method for corrosive foundation environments uses the gradient grouting reinforcement test device for corrosive foundation environments as described in the first aspect, comprising: achieving gradient grouting at different depths by rotating the inner grouting tube; and accelerating the corrosion of the pile foundation by simulating marine corrosion environment and terrestrial corrosive foundation through a steel bar electrochemical accelerated corrosion system.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The gradient grouting mechanism of this invention includes a grouting circular inner tube, a grouting circular outer tube sleeved outside the grouting circular inner tube, and multiple grouting circular inclined tubes disposed on the grouting circular outer tube; a gap is left between the grouting circular inner tube and the grouting circular outer tube; the gradient grouting mechanism achieves precise gradient grouting at different depths through the rotational movement of the grouting inner tube, and can simulate marine corrosion environment and terrestrial corrosive foundation through the steel reinforcement electrochemical accelerated corrosion system, thereby accelerating the corrosion of pile foundations, and on this basis, the pile body is reinforced by gradient grouting, which can accurately simulate the actual corrosive foundation environment, providing an effective experimental means and scientific basis for the repair and reinforcement of pile foundations under corrosive environments. Attached Figure Description

[0016] The accompanying drawings, which form part of this embodiment, are used to provide a further understanding of this embodiment. The illustrative embodiments and their descriptions are used to explain this embodiment and do not constitute an improper limitation of this embodiment.

[0017] Figure 1 This is a schematic diagram of the overall device of the present invention; Figure 2 This is a schematic diagram of the top of the device of the present invention; Figure 3 This is a schematic diagram of the cross-section of the precast concrete pile of the present invention; Figure 4 This is a schematic diagram of the precast concrete pile of the present invention; Figure 5 This is a schematic diagram of the gradient grouting mechanism of the present invention; Figure 6 This is a schematic cross-sectional view of the gradient grouting mechanism of the present invention (1-1). Figure 7 This is a schematic cross-sectional view of the gradient grouting mechanism of the present invention (2-2). Figure 8 This is a schematic cross-sectional view of the gradient grouting mechanism of the present invention (3-3). Figure 9 This is a schematic diagram showing the connection between the grouting inner pipe and the grouting inclined pipe at different depths in the gradient grouting mechanism of Embodiment 1 of the present invention; Figure 10 This is a flowchart illustrating the linkage between the model experiment and the on-site grouting reinforcement of existing pile foundations in Embodiment 1 of the present invention. The components include: 1. Power supply; 2. Conductor; 3. Precast concrete pile; 4. Longitudinal reinforcement; 41. First longitudinal reinforcement; 42. Second longitudinal reinforcement; 43. Third longitudinal reinforcement; 5. Gradient grouting mechanism; 6. Annular hoop; 61. First transverse section reinforcement; 62. Second transverse section reinforcement; 63. Third transverse section reinforcement; 7. Reinforcing mesh; 8. Graphite; 9. Water inlet; 10. Drainage hole; 11. Model box system; 12. Water pump; 13. Grouting circular inner pipe; 14. Grouting circular outer pipe; 15. First grouting circular inclined pipe; 16. Second grouting circular inclined pipe; 17. Third grouting circular inclined pipe; 18. Circular rotating support; 19. Annular rubber pad. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0020] like Figure 1 As shown, the present invention provides a gradient grouting reinforcement test device in a corrosive foundation environment, including a model box, precast concrete piles (steel pipe piles and precast concrete piles), a gradient grouting mechanism, and a steel reinforcement electrochemical accelerated corrosion system.

[0021] The model box 11 has two drainage holes 10 on its bottom plate and two water inlets 9 installed on the top of its side plate. The water inlets 9 are connected to the water pump 12. The precast concrete pile 3 has eight longitudinal bars 4 along its length, three of which are connected to the pile's circumferential ring 6 at different heights. Figure 5 As shown, the gradient grouting mechanism 5 includes a grouting circular inner tube 13, a grouting circular outer tube 14, a first grouting circular inclined tube 15, a second grouting circular inclined tube 16, and a third grouting circular inclined tube 17, etc.; wherein, the grouting circular inner tube 13 and the grouting circular outer tube 14 are connected by a circular rotating support 18, and a certain gap is left between them to facilitate the rotation of the grouting inner tube 13 inside the grouting outer tube 14; the steel reinforcement electrochemical accelerated corrosion system includes a circuit formed by five parts: steel mesh 7, power supply 1, wire 2, and graphite 8.

[0022] Optionally, the model box 11 has a length × width × height of 3m × 3m × 2m, and the bottom plate and side plate are both made of 10mm thick steel plate. Square steel pipes with a side length of 10cm are set at 50cm intervals on the sides and bottom plate of the model box 11 to form a constraint frame. The bottom plate has two drainage holes 10, and two water inlets 9 are installed on the top of the side plate. The water inlets are connected to the water pump 12, and seawater and NaCl solution are injected into the model box by pressurization.

[0023] Optionally, before the test, waterproof insulating material is laid and pasted on the side wall and bottom plate of the model box 11, and a bottom water outlet 10 is reserved; two water inlets 9 are installed on the top of the side wall of the model box 11 for injecting seawater or pre-prepared corrosive solution into the model box; two water outlets 10 are set on the bottom plate of the model box 11 and the water outlet valve is installed on the water outlet 10 with sealant, so as to form flowing water during the preparation of corrosive foundation, which is convenient for the preparation of saturated or semi-saturated foundation, and the mass of seawater or corrosive solution injected into the model box and the mass of liquid flowing out of the model box are precisely controlled by installing a flow meter, so as to precisely control the moisture content of the foundation soil, as shown in formula (1): (1) In this embodiment, the foundation soil layers (cohesive soil, silt, and sand) are laid in layers inside the model box. The foundation soil inside the model box is laid according to the principle of "layered and multiple fillings, with uniform compaction layer by layer". Before filling, the maximum and minimum dry densities of the foundation soil are measured. ρ d，max ρ d，min ， The elevation for each filling is set as follows: h i According to the net length of the model box a Net width b and the set foundation soil compaction degree D r The mass of the foundation soil in each layer is calculated according to formula (2). m i : (2) like Figure 2 As shown, the gradient grouting mechanism 5 performs grouting at three angles spaced 120° apart and at three different depths (upper, middle and lower parts of the precast concrete pile) around the precast concrete pile 3.

[0024] like Figure 3 and Figure 4 As shown, the top of the longitudinal reinforcement of the precast concrete pile 3 extends 0.5m above the pile top elevation. The first longitudinal reinforcement 41, the second longitudinal reinforcement 42 and the third longitudinal reinforcement 43 are welded to the pile perimeter ring 6 at different elevation positions through the first transverse section reinforcement 61, the second transverse section reinforcement 62 and the third transverse section reinforcement 63, respectively, and the pile perimeter ring 6 is tightly attached to the precast concrete pile 3.

[0025] like Figure 6 , Figure 7 and Figure 8As shown, the bottom of the grouting circular inner tube 13 is connected to a circular rotating support 18. The top of the circular rotating support 18 is welded to the bottom of the grouting circular inner tube 13, and the bottom of the circular rotating support 18 is welded to the top of the grouting circular outer tube 14. The grouting circular outer tube 14 has annular rotating shafts embedded at intervals of 0.5m along its entire length, which contact but are not connected to the grouting circular inner tube 13. The grouting circular inner tube 13 has curved square holes at three positions: elevation H4, H3+H4, and H2+H3+H4. The three curved square holes are located at three different elevations and are spaced 120° apart on the horizontal projection. The first grouting circular inclined tube 15, the second grouting circular inclined tube 16, and the third grouting circular inclined tube 17 are welded to the outer grouting circular tube 14 at three elevation positions: H4, H3+H4, and H2+H3+H4, respectively, forming a 120° angle with the outer grouting circular tube 14. The first grouting circular inclined tube 15, the second grouting circular inclined tube 16, and the third grouting circular inclined tube 17 extend into the interior of the outer grouting circular tube 14 and are in tight contact with the outer wall of the inner grouting circular tube 13 through a clamping annular rubber pad 19. The ends of the first grouting circular inclined tube 15, the second grouting circular inclined tube 16, and the third grouting circular inclined tube 17 are perforated to install geotextile filter cloth to prevent sand from entering the interior of the inclined tube.

[0026] like Figure 8 As shown, the steel mesh 7 is composed of five pieces connected together. Four pieces are connected vertically to form a "well" shape, and the other piece of steel mesh is placed horizontally. The overlapping parts of the five steel meshes are connected by "lapped steel bars". The steel mesh 7 is installed by pre-embedding and is not connected to the model box system 11. The parts that contact the model box system 11 are insulated at the ends of the steel mesh 7.

[0027] Optionally, the closest distance between each piece of the "well"-shaped steel mesh and the precast concrete pile 3 is greater than 5D (D is the pile diameter) and does not affect the arrangement of the gradient grouting mechanism 5; another piece of steel mesh is placed horizontally, with the horizontal elevation located outside the range of 5D (D is the pile diameter) below the pile end. The overlapping parts of the five steel meshes are connected by "lapped steel bars". The steel mesh 7 is installed by pre-embedding and is not connected to the model box 11. The part in contact with the model box 11 is insulated at the end of the steel mesh 7.

[0028] Optionally, both horizontal and vertical steel meshes are made of steel mesh with a diameter of 2mm and a spacing of 1cm. The horizontal and vertical steel meshes are connected by "lapped steel bars" and secured with steel wire.

[0029] The verticality of the precast model piles is calibrated using a laser head projection instrument. After the precast model piles are "embedded" to the design elevation, the longitudinal reinforcement at the pile end and the horizontal steel mesh are connected by "lapped reinforcement" and secured with steel wire.

[0030] Three earth pressure cells are fixed to the annular hoop (same cross section) of the precast model pile using structural adhesive. The three earth pressure cells are horizontally aligned with the ends of the circular grouting inclined pipes of the three gradient grouting mechanisms (near the precast model pile side) to measure the pressure value experienced by the precast model pile during grouting, thus determining the grouting effect around the pile. Three pressure cell sensors (same cross section, 120° apart) are also fixed to the annular hoop of the precast model pile using structural adhesive. These pressure sensors are horizontally aligned with the ends of the circular grouting inclined pipes of the three gradient grouting mechanisms (near the precast model pile side) to measure the pressure value experienced by the precast model pile during grouting, thus determining the grouting effect around the pile. A laser head projection instrument is used to calibrate the verticality of the shave grouting device. The three shave grouting devices grout synchronously. Before grouting, the inner grouting tube is rotated until the upper grouting inclined pipe opening is opened. During grouting, the grouting volume is recorded and the pressure sensor data around the precast concrete pile is recorded. The inner grouting tube is rotated sequentially to grout the middle and lower parts of the pile. By connecting the reinforcing mesh, precast concrete pile longitudinal reinforcement, and power source with wires, and binding the graphite to the mud-surface reinforcing mesh, an electrical circuit is formed: "positive power source → precast concrete pile longitudinal reinforcement → reinforcing mesh → graphite → negative power source". Electrochemical corrosion accelerates the deterioration of the precast concrete pile in the corrosive foundation environment.

[0031] like Figure 1 As shown, the positive terminal of power supply 1 is connected to the first longitudinal reinforcement 41, the second longitudinal reinforcement 42 and the third longitudinal reinforcement 43 through wire 2; the negative terminal of power supply 1 is connected to the steel mesh 7 through wire 2, and graphite 8 is fixed to the steel mesh on the surface of saturated foundation soil; the power supply is connected to the precast concrete pile to form a circuit through wire 2, steel mesh 7 and graphite 8, and seawater or prepared NaCl solution is injected into the model box through water inlet 9 and water pump 12.

[0032] In summary, the device of this invention includes a model box, precast piles (steel pipe piles and precast concrete piles), a gradient grouting mechanism, and a steel reinforcement electrochemical accelerated corrosion system. The model box is equipped with an inlet and an outlet, enabling precise control of the moisture content of seawater or corrosive foundations. The upper and lower longitudinal reinforcement bars of the precast concrete piles extend beyond both ends of the pile body (steel pipe piles have welded reinforcement bars at the pile top and end), facilitating connection with the steel reinforcement electrochemical accelerated corrosion system to accelerate the corrosion process. The steel reinforcement electrochemical accelerated corrosion system consists of a "well"-shaped steel mesh, graphite electrodes, and an external power source, accelerating the corrosion of precast piles in a corrosive foundation environment through electrochemical methods. The gradient grouting mechanism achieves precise gradient grouting at different depths through the rotation of the grouting inner tube, and uses pressure sensors to monitor and control the grouting pressure and volume in real time. This invention can simulate marine corrosive environments and corrosive terrestrial foundations, achieving accelerated corrosion of pile foundations. Based on this, it reinforces the pile body through gradient grouting, providing an effective experimental method and scientific basis for the repair and reinforcement of pile foundations in corrosive environments.

[0033] This invention also provides a test method for gradient grouting reinforcement of precast concrete piles in corrosive foundation environments, the steps of which are as follows: S001. First, the ion type, ion concentration and water content of the foundation soil are determined according to the experimental design. The total mass and total height of the foundation soil are calculated. The foundation soil is laid according to the principle of "layered and multiple fillings and uniform compaction of each layer". The mass of the foundation soil corresponding to the laying height of each layer is calculated. During the laying process, the laying height and the laying mass are always kept in a one-to-one correspondence.

[0034] S002. First, lay the foundation soil to the level of the horizontal steel mesh, place the steel mesh, overlap the vertical steel mesh, and temporarily fix the vertical steel mesh; at the same time, position the precast concrete piles, overlap the pile end steel bars with the horizontal steel mesh, and fix the precast concrete piles.

[0035] S003. Continue laying the foundation soil to the bottom of the precast concrete pile. During the laying of the foundation soil, always keep the horizontal steel mesh perpendicular to the precast concrete pile. Then position the gradient grouting mechanism and pre-embed the three gradient grouting mechanisms at 120°. Continue laying the foundation soil in layers to the designed total height.

[0036] S004. After the foundation soil is laid, inject a corrosive solution into the model box through the water inlet to the designed concentration, and strictly control the quality of the liquid injected into the model box to ensure precise control of the water content.

[0037] S005. After the corrosion solution is injected, a wire is used to connect the circuit to form an electrical circuit of "positive power supply → precast concrete pile longitudinal reinforcement → steel mesh → graphite → negative power supply". The circuit is then energized to accelerate corrosion. Different energizing durations can be set to simulate different accelerated corrosion times.

[0038] S006. After the accelerated corrosion is completed, disconnect the circuit and inject grout into the grouting device in a gradient, following the grouting principle of "first the top, then the middle, and finally the bottom". During the grouting process, record the pressure sensor data, grouting pressure and grouting time. After the grouting is completed, let it stand according to the grout curing time until the grout hardens.

[0039] S007. Cut off the longitudinal reinforcement at the top of the pile, and conduct horizontal static load or vertical static load tests on the precast concrete pile to obtain the horizontal / vertical ultimate bearing capacity (F) of the grouting-reinforced pile foundation. H注浆 / F V注浆 ).

[0040] S008. After the test, empty the model box and, following the same procedures as steps S001 to S006 (without installing a gradient grouting mechanism or performing grouting), conduct accelerated corrosion tests on the ungrouted model piles. Perform horizontal static load or vertical static load tests on the precast concrete piles to obtain the horizontal / vertical ultimate bearing capacity (F) of the ungrouted reinforced pile foundation. H不注浆 / F V不注浆 ).

[0041] S009. Comparative analysis of the horizontal / vertical ultimate bearing capacity (F) of grouting-reinforced pile foundations. H注浆 / F V注浆 ) and the horizontal / vertical ultimate bearing capacity (F) of ungrouted pile foundations H不注浆 / F V不注浆 This study reveals the effect of grouting reinforcement on the horizontal / vertical bearing capacity of pile foundations, clarifies its contribution to enhancing pile-soil interaction and improving pile side and end resistance, and provides a quantitative basis for selecting reinforcement schemes in pile foundation engineering design.

[0042] Example 1: This embodiment provides a gradient grouting reinforcement test device and a gradient grouting reinforcement test method in a corrosive foundation environment. It can be combined with existing pile foundation grouting reinforcement projects to provide technical guidance for grouting reinforcement in actual projects.

[0043] The corrosive foundation soil in the actual engineering area was investigated. The parameters obtained from the corrosive foundation investigation included, but were not limited to: groundwater level fluctuations, soil resistivity, pH value, Cl- ion concentration, and SO42- ion concentration.

[0044] In the laboratory, a systematic model test was conducted using the invention device to simulate the actual service conditions of the pile foundation on site. The model foundation soil was configured according to the actual engineering foundation conditions to ensure that the parameters of the two were consistent.

[0045] The corrosion of the precast concrete pile model is accelerated by energizing it. At the same time, sensors (such as steel corrosion sensors and strain gauges) embedded in the precast concrete pile and non-destructive testing (such as ultrasonic testing of the model pile) are used to monitor and record the corrosion rate, corrosion pit development and stress-strain changes at different depths of the pile in real time.

[0046] After the test, the model pile was removed for destructive testing, and the corrosion depth, area, and distribution pattern were accurately measured. The monitoring data and destructive test results were combined to create a "Pile Corrosion Risk Location Map." This map clearly identifies the sections of the pile most susceptible to severe corrosion under specific environmental and load conditions (e.g., areas of fluctuating groundwater levels, interfaces of abrupt changes in soil properties, areas of maximum bending moment, etc.).

[0047] Based on the "Pile Corrosion Risk Location Map," a targeted grouting strategy was developed. Key reinforcement zones: These correspond to the severely corroded sections shown in the model tests. The grouting objective in this area is not only to fill the pile-soil gap but also to form a high-strength, corrosion-resistant grout envelope, providing a constricting effect and reinforcement to the potentially damaged pile body. General protection zones: For sections with slight corrosion or potential corrosion risk, the grouting objective is mainly to fill gaps and isolate corrosive media. Non-essential grouting zones: Sections with extremely low corrosion risk can avoid grouting to save costs.

[0048] On-site surveys and corrosion diagnosis of target piles were conducted using non-destructive testing methods such as low-strain dynamic testing and sonic logging to comprehensively assess the integrity of the pile body and preliminarily determine the presence and approximate location of any obvious defects. The on-site survey results were compared with a "pile corrosion risk location map" to estimate the key areas where corrosion is most likely to occur in the specific pile foundation at that site (even if non-destructive testing does not clearly show defects, preventive reinforcement should be carried out based on model predictions).

[0049] Based on the key areas of the pile foundation most likely to corrode, targeted grouting should be designed and implemented. Two to four sleeve valve grouting pipes or one-way valve grouting pipes should be symmetrically arranged around the piles. The grouting hole opening intervals of the grouting pipes should strictly correspond to the "key reinforcement zone" and "general protection zone" determined by model tests, rather than being uniformly distributed along the entire length. For example, if the model shows that corrosion mainly occurs in the range of 3m to 8m below the pile top, the grouting pipes should be concentrated in this interval. A grout formulation (such as a high-performance cement-based grout with a specific proportion of corrosion inhibitor and expansion agent) that has been verified in model tests and has good resistance and mechanical properties to the simulated corrosive environment should be used for on-site construction.

[0050] First, grouting is performed on the "key reinforcement area." A grouting process with a low flow rate and high pressure is used to ensure that the grout can fully penetrate to the pile-soil interface and may partially split into the disturbed soft soil around the pile, forming an enlarged head reinforcement effect. The reinforcement effect is judged by monitoring changes in grouting pressure and volume. Then, grouting is performed on the "general protection area." Conventional grouting parameters can be used, with the main purpose of filling and sealing. During the grouting process, pile top displacement monitoring and necessary stress monitoring are combined to prevent adverse effects such as pile lifting. Distributed fiber optic sensing technology can be used to monitor strain changes in the pile body during grouting, indirectly evaluating the grout encapsulation effect.

[0051] After the grout reaches its design strength, methods such as sonic logging, high-strain dynamic pile testing, or static load testing are used to verify the pile integrity and the improvement in single pile bearing capacity. The verification results are compared with the predictions from model tests and the reinforcement targets to complete the closed-loop management of this reinforcement project and provide data support for decision-making in subsequent similar projects. The flowchart for this case study is shown below. Figure 10 As shown.

[0052] The above description is merely a preferred embodiment of this practice and is not intended to limit the scope of this practice. Various modifications and variations can be made to this practice by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this practice should be included within the protection scope of this practice.

Claims

1. A test device for gradient grouting reinforcement in a corrosive foundation environment, characterized in that, It includes a model box, as well as precast concrete piles, a gradient grouting mechanism, and a steel reinforcement electrochemical accelerated corrosion system installed in the model box; The gradient grouting mechanism includes a grouting circular inner tube, a grouting circular outer tube sleeved outside the grouting circular inner tube, and multiple grouting circular inclined tubes disposed on the grouting circular outer tube; a gap is left between the grouting circular inner tube and the grouting circular outer tube, and gradient grouting at different depths is achieved by rotating the grouting circular inner tube. The gradient grouting mechanism is multiple, and the multiple gradient grouting mechanisms are evenly arranged at a preset angle around the precast concrete pile. The bottom of the grouting circular inner tube is connected to a circular rotating support, the top of the circular rotating support is connected to the bottom of the grouting circular inner tube, and the bottom of the circular rotating support is connected to the bottom of the grouting circular outer tube. The grouting circular outer tube is embedded with an annular rotating shaft that contacts the grouting circular inner tube. The grouting circular inner tube is provided with curved square holes at multiple locations. The multiple curved square holes are located at three preset elevations and are spaced 120° apart on the horizontal projection.

2. The gradient grouting reinforcement test device in a corrosive foundation environment as described in claim 1, characterized in that, The model box has a drainage hole at the bottom and a water inlet on the side, which is connected to a water pump.

3. The gradient grouting reinforcement test device in a corrosive foundation environment as described in claim 2, characterized in that, The model box contains layers of foundation soil, and the maximum and minimum dry densities of the foundation soil were measured. ρ d，max ρ d，min ， The elevation for each filling is set as follows: h i According to the net length of the model box a Net width b and the set foundation soil compaction degree D r The mass of the foundation soil in each layer was obtained. m i : 。 4. The gradient grouting reinforcement test device in a corrosive foundation environment as described in claim 1, characterized in that, The precast concrete pile includes multiple longitudinal bars, which are connected to the pile's circumferential ring at different heights.

5. The gradient grouting reinforcement test device in a corrosive foundation environment as described in claim 1, characterized in that, The steel reinforcement electrochemical accelerated corrosion system includes a power source and a steel mesh connected to one end of the power source via a conductor; the other end of the power source is connected to the precast concrete pile via a conductor.

6. The gradient grouting reinforcement test device in a corrosive foundation environment as described in claim 5, characterized in that, The positive terminal of the power supply is connected to the longitudinal reinforcement of the precast concrete pile via a wire; the negative terminal of the power supply is connected to the steel mesh via a wire, and graphite is placed on the steel mesh.

7. The gradient grouting reinforcement test device in a corrosive foundation environment as described in claim 1, characterized in that, The precast concrete pile is provided with a first longitudinal bar, a second longitudinal bar, and a third longitudinal bar, which are connected to the pile perimeter ring plate at different elevation positions through the first transverse section steel bar, the second transverse section steel bar, and the third transverse section steel bar.

8. A test method for gradient grouting reinforcement in a corrosive foundation environment, characterized in that, The gradient grouting reinforcement test device in a corrosive foundation environment as described in any one of claims 1-7 is used, comprising: achieving gradient grouting at different depths by rotating the inner grouting tube; and simulating marine corrosion environment and terrestrial corrosive foundation by using a steel bar electrochemical accelerated corrosion system to accelerate the corrosion of the pile foundation.

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