A method for reinforcing a cast-in-place pile in deep and soft soil layer and a model

Abstract

The application provides a cast-in-place pile reinforcing method and model for deep and thick soft soil layer, which comprises the following steps: performing early construction on the construction site, wherein the early construction comprises site leveling, pile position lofting and casing burying; drilling a high-pressure rotary jetting drill bit to a soft soil pre-reinforcing depth, then spraying cement into the soil body in a high-pressure form and lifting the drill rod at a preset speed, so that the cement slurry and soil particles are fully stirred and uniformly distributed; cement slurry coagulation and hardening form a closed annular reinforcing area in the soft soil layer around the pile hole, so that the soft soil layer pre-reinforcing construction is realized; performing hole forming construction, and performing quality acceptance on the formed hole, then performing reinforcing cage and steel guide pipe construction, and then pouring concrete. The cast-in-place pile reinforcing method and model for deep and thick soft soil layer provided by the application proposes that the high-pressure rotary jetting pile is used to pre-reinforce the soft soil layer around the pile hole, and the rotary drilling machine is used to form a hole after the closed annular reinforcing area is formed in the soft soil layer around the pile hole.

Description

Technical Field

[0001] The present invention belongs to the technical field of pile foundation engineering, specifically, to a method and a model for reinforcing cast-in-place piles in deep soft soil layers, and more specifically, to a method and a model for reinforcing cast-in-place piles in deep soft soil layers. Background Art

[0002] With the gradual acceleration of urbanization, pile foundation construction has developed rapidly, and the complexity and difficulty of pile foundation construction are constantly increasing. Especially in the eastern coastal areas, the complex environment surrounding urban construction often encounters deep and soft soil conditions during construction, most of which are silty soft soil, and the soft soil layer is relatively thick. Efficient construction equipment and advanced construction technology are urgently needed to solve the problems that arise during pile foundation construction in soft soil areas.

[0003] Currently, the mainstream construction equipment used at bored pile construction sites is the rotary drilling rig. In some areas with deep, soft soil layers in the middle and lower reaches of the Yangtze River, the soil is generally in a plastic state, making conventional static mud wall reinforcement ineffective in supporting the hole wall. When using the reinforcement method of replacing and lengthening the casing, the soft soil at the bottom of the hole cannot be effectively reinforced due to the thick and deep soft soil layer. When using the full-casing rotary drilling construction method, the casing is pressed down through the deep, soft soil layer by a vibrating hammer, vibrating and liquefying the surrounding soft soil, reducing the soft soil strength and causing the casing to tilt and shift during the downward pressure, thus affecting the quality of the pile. Rotary drilling rigs are prone to problems such as hole collapse and necking when drilling holes in highly sensitive soft soil layers. Summary of the Invention

[0004] The purpose of the present invention is to provide a bored pile reinforcement method and model for deep soft soil layers, aiming to solve the technical problem that existing bored pile hole wall reinforcement measures in soft soil layers are prone to hole collapse, necking and other problems.

[0005] To achieve the above object, the present invention adopts a technical solution of providing a cast-in-place pile reinforcement method for deep soft soil layers, comprising the following steps:

[0006] Carry out preliminary construction on the construction site, including site leveling, pile position setting, and casing burial;

[0007] The high-pressure jet-jet drill drills to the soft soil pre-reinforcement depth, then sprays cement into the soil at high pressure and lifts the drill rod at a preset speed to fully mix the cement slurry and soil particles. As the cement slurry solidifies, it forms a closed annular reinforcement zone in the soft soil layer around the pile hole, achieving pre-reinforcement of the soft soil layer.

[0008] Carry out hole-forming construction and conduct quality acceptance of the holes;

[0009] The construction of steel cage and steel conduit is carried out, and then the concrete is poured.

[0010] Preferably, the pile position setting out comprises the following steps:

[0011] According to the coordinate points of the pile on the design drawing, place the center position of the pile;

[0012] Mark the pile position at the center point of the pile.

[0013] Preferably, the casing embedding includes the following steps:

[0014] The casing is buried in a vertical position at the construction site, with the deviation between the center of the casing and the center line of the pile position not exceeding 20mm; the top of the casing is 0.3m-0.5m above the ground.

[0015] Preferably, the hole forming construction comprises the following steps:

[0016] After the pile position is verified to be correct and the casing is buried in accordance with the requirements, the drilling rig is put in place; the drilling rig is kept in a flat and vertical position to ensure that the pile hole is vertical;

[0017] Use a rotary drilling rig to carry out hole drilling operations.

[0018] Preferably, the quality inspection of the pores includes the following steps:

[0019] Check the hole diameter, hole depth, verticality and sediment thickness separately.

[0020] Preferably, the construction of the steel cage and the steel conduit comprises the following steps:

[0021] The annular stirrups are connected to the main reinforcement by welding, and the spiral stirrups are connected to the main reinforcement by tying and welding; the width of the steel bar lap weld is not less than 0.7d, and the thickness of the lap weld is not less than 0.3d; the reinforcing hoops are set on the outside of the main reinforcement, and the lifting point of the steel cage is set at the reinforced stirrup position; the pile end grouting pipe and the steel cage are fixed by tying or welding and are evenly arranged; the top of the grouting pipe is 200mm above the ground, the pipe mouth is closed, and the lower end extends into the bottom of the bored pile hole 300mm-500m, and the guide tube is lowered section by section and installed.

[0022] Preferably, protective layer pads are set on the steel cage to ensure the thickness of the protective layer, and the number of protective layer pads set for each section of the steel cage is not less than 2 groups. When the length is greater than 12m, an additional group is added in the middle, with no less than 3 blocks in each group, and evenly distributed on the main reinforcement of the same section.

[0023] Preferably, pouring concrete comprises the following steps:

[0024] When continuous pouring is done using the conduit method, ensure that the bottom of the conduit is buried 0.8m-1.3m into the concrete for the first pouring.

[0025] As the volume of concrete pouring increases, the guide tube is intermittently lifted and removed to keep the buried depth of the guide tube 2m-6m below the concrete surface;

[0026] The top elevation of the cast-in-place pile is 0.8m-1.0m higher than the design elevation to ensure the strength of the concrete at the top of the pile.

[0027] Preferably, the slump of the concrete has a numerical range of 180 mm to 220 mm.

[0028] The present invention also provides a model for reinforcing cast-in-place piles in deep and soft soil layers, which is characterized by comprising:

[0029] The data acquisition module is configured to acquire aperture horizontal displacement data of rotary bored piles with different reinforcement thicknesses in several preset typical aperture working conditions;

[0030] The reinforcement thickness limit determination module is configured to determine the upper limit h of the reinforcement thickness of the rotary bored piles in several typical aperture working conditions based on the aperture horizontal displacement data of the rotary bored piles at different reinforcement thicknesses in the several typical aperture working conditions. max and the lower limit of reinforcement thickness h min ;

[0031] A formula module is configured to fit a calculation formula for the optimal reinforcement thickness h of the bored piles in different hole diameter working conditions based on the upper limit and lower limit of the reinforcement thickness of the bored piles in the several typical hole diameter working conditions;

[0032] The evaluation module is configured to calculate the optimal reinforcement thickness h of the bored piles in several typical hole diameter working conditions according to the calculation formula of the optimal reinforcement thickness h of the bored piles in different hole diameter working conditions, and compare it with the upper limit and lower limit of the reinforcement thickness of the bored piles in several typical hole diameter working conditions until h is satisfied. min ≤h≤h max .

[0033] The beneficial effects of the bored pile reinforcement method and model for deep soft soil layers provided by the present invention are: compared with the existing technology, the bored pile reinforcement method and model for deep soft soil layers provided by the present invention pre-reinforce the soft soil layer around the pile hole by spraying cement into the soil in the form of high pressure and fully mixing the cement slurry and soil particles. After the cement slurry solidifies and a closed annular reinforcement area is formed in the soft soil layer around the pile hole, a rotary drilling rig is used to drill the hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 A flowchart of a method for reinforcing deep and soft soil layers with cast-in-place piles provided by an embodiment of the present invention;

[0036] Figure 2 A flowchart of a cast-in-place pile model for deep soft soil layers provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0038] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0039] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0040] Please also refer to Figure 1 and Figure 2 The present invention provides a method and model for reinforcing a cast-in-place pile in a deep and soft soil layer. The method comprises the following steps:

[0041] Carry out preliminary construction on the construction site, including site leveling, pile position setting, and casing burial;

[0042] The realization of site leveling includes the following steps: leveling and hardening the site to form a working platform.

[0043] The implementation of pile position layout includes the following steps: locating the center position of the pile according to the coordinate points of the pile on the design drawing; and marking the pile position at the center point of the pile position.

[0044] The implementation of casing burial includes the following steps: burying the casing in a vertical posture at the construction site, with the deviation range between the casing center and the pile center line being 0mm-20mm; the top of the casing is 0.3m-0.5m above the ground.

[0045] The high-pressure jet-jet drill drills to the soft soil pre-reinforcement depth, then sprays cement into the soil at high pressure and lifts the drill rod at a preset speed to fully mix the cement slurry and soil particles. As the cement slurry solidifies, it forms a closed annular reinforcement zone in the soft soil layer around the pile hole, achieving pre-reinforcement of the soft soil layer.

[0046] Carry out hole-forming construction and conduct quality acceptance of the holes;

[0047] The implementation of hole construction includes the following steps: after the pile position is verified to be correct and the casing is buried in accordance with the requirements, the drilling rig is positioned; the drilling rig is kept in a flat and vertical position to ensure the verticality of the pile hole; the rotary drilling rig is used to perform the hole drilling operation.

[0048] The quality acceptance of the hole is carried out in the following steps: checking the hole diameter, hole depth, verticality and sediment thickness respectively.

[0049] The construction of steel cage and steel conduit is carried out, and then the concrete is poured.

[0050] The construction of steel cage and steel conduit includes the following steps:

[0051] The annular stirrups are connected to the main reinforcement by welding, and the spiral stirrups are connected to the main reinforcement by tying and welding; the width of the steel bar lap weld is not less than 0.7d, and the thickness of the lap weld is not less than 0.3d; the reinforcing hoops are set on the outside of the main reinforcement, and the lifting point of the steel cage is set at the reinforced stirrup position; the pile end grouting pipe and the steel cage are fixed by tying or welding and are evenly arranged; the top of the grouting pipe is 200mm above the ground, the pipe mouth is closed, and the lower end extends into the bottom of the bored pile hole 300mm-500m, and the guide tube is lowered section by section and installed.

[0052] Protective layer pads are set on the steel cage to ensure the thickness of the protective layer, and the number of protective layer pads set for each section of the steel cage is not less than 2 groups. When the length is greater than 12m, an additional group is added in the middle, with no less than 3 blocks in each group, and they are evenly distributed on the main reinforcement of the same section.

[0053] Pouring concrete involves the following steps:

[0054] When continuous pouring is done using the conduit method, ensure that the bottom of the conduit is buried 0.8m-1.3m into the concrete for the first pouring.

[0055] As the volume of concrete pouring increases, the guide tube is intermittently lifted and removed to keep the buried depth of the guide tube 2m-6m below the concrete surface;

[0056] The top elevation of the cast-in-place pile is 0.8m-1.0m higher than the design elevation to ensure the strength of the concrete at the top of the pile.

[0057] The numerical range of concrete slump is 180mm-220mm.

[0058] The present invention provides a cast-in-place pile reinforcement method for deep soft soil layers. Compared with the existing technology, the soft soil layer around the pile hole is pre-reinforced by spraying cement into the soil in the form of high pressure and fully mixing the cement slurry and soil particles. After the cement slurry solidifies and a closed annular reinforcement area is formed in the soft soil layer around the pile hole, a rotary drilling rig is used to drill the hole.

[0059] Example 1

[0060] The present invention provides a method for reinforcing deep and soft soil layers with cast-in-place piles, comprising the following steps:

[0061] Preliminary construction phase of the construction site

[0062] S1. Site leveling

[0063] Step S1 includes the following steps:

[0064] Step S1.1, leveling and hardening the site;

[0065] Step S1.2, forming an operating platform;

[0066] The working platform is flat and spacious to facilitate the entry and exit of construction equipment, material transportation and operations.

[0067] S2. Pile position setting out

[0068] Step S2 includes the following steps:

[0069] Step S2.1: Draw a design drawing based on the construction site and preset the location of the cast-in-place piles. Use a total station to locate the center of the cast-in-place piles according to the coordinate points of the cast-in-place piles on the design drawing. That is, use the total station to locate the center of all cast-in-place piles on the design drawing.

[0070] Step S2.2: Drive a steel bar into the center of the cast-in-place pile as a pile mark, i.e., mark all cast-in-place piles designed in the drawing.

[0071] S3. Casing Burial

[0072] Step S3 includes the following steps:

[0073] Step S3.1, bury the casing in a vertical position at the construction site, with the deviation between the center of the casing and the pile center cross line drawn around the pile position no more than 20 mm; the top of the casing is 0.3m-0.5m above the ground;

[0074] The prevention positions of the casing and the bored piles correspond one to one.

[0075] Pre-reinforcement construction stage of soft soil layer

[0076] S4. Pre-reinforcement construction of soft soil layer

[0077] Step S4 includes the following steps:

[0078] Step S4.1: Use high-pressure jet grouting piles to pre-reinforce the soft soil layer around the pile hole (and the pile hole of the cast-in-place pile). Use a high-pressure jet grouting drill bit to drill to the soft soil pre-reinforcement depth through a drilling rig. Use a high-pressure nozzle to spray cement slurry into the soil at high pressure and raise the drill rod at a certain speed (specifically, the value range can be 1m / min-2m / min) to ensure that the cement slurry and soil particles are fully mixed.

[0079] Step S4.2: After the cement slurry solidifies and hardens to form a stable cement soil, a closed annular reinforcement area is formed in the soft soil layer around the pile hole, and then a rotary drilling rig is used to drill the hole;

[0080] Hole construction stage

[0081] S5, drilling rig in place, hole position calibration;

[0082] Step S5 includes the following steps:

[0083] Step S5.1: If the pile position is correct and the casing is buried in accordance with the requirements, the drilling rig is put into place;

[0084] Step S5.2: The drilling rig is in a flat and vertical position to ensure that the pile hole is vertical;

[0085] S6, forming holes and unloading soil;

[0086] Step S6 includes the following steps:

[0087] Step S6.1, using a rotary drilling rig to perform hole drilling operations;

[0088] Step S6.2: transporting the soil to the designated location;

[0089] S7. Quality Acceptance

[0090] Step S7 includes the following steps:

[0091] Step S7.1, check the hole diameter, hole depth, verticality, and sediment thickness respectively to ensure that the hole formation indicators meet the specification requirements;

[0092] Concrete pouring stage

[0093] S8. Construction of steel cage and steel conduit

[0094] In this step, the steel cage is manufactured in sections, and the length of each section is determined based on a comprehensive consideration of three factors: the overall stiffness of the cage, the length of the material, and the effective height of the lifting equipment.

[0095] The width of the steel bar lap weld shall not be less than 0.7d, and the thickness of the lap weld shall not be less than 0.3d.

[0096] The lap weld length of HPB300 grade steel bars is 8d for single-sided welding and 4d for double-sided welding; the lap weld length of HPB335 grade steel bars is 10d for single-sided welding and 5d for double-sided welding.

[0097] Step S8 includes the following steps:

[0098] S8.1: Circular stirrups are spot welded to the main reinforcement, and spiral stirrups are tied and spot welded at intervals or directly to the main reinforcement;

[0099] S8.2: Cover pads shall be installed on the reinforcement cage to ensure the cover thickness. The number of cover pads shall be not less than 2 per section of reinforcement cage. For cages longer than 12 m, an additional group shall be installed in the middle. Each group shall be not less than 3 and shall be evenly distributed on the main reinforcement of the same cross section.

[0100] S8.3: Stiffening hoops shall be installed outside the main reinforcement. The lifting points of the steel cage shall be located at the location of the reinforcing hoops. Appropriate measures shall be taken to prevent deformation during transportation and installation.

[0101] S8.4: The pile end grouting pipe and reinforcement cage shall be fixed by tying or welding and evenly arranged. The reinforcement cage shall be lowered to the design elevation.

[0102] S8.5: The top of the grouting pipe shall be 200 mm above the ground, the pipe mouth shall be closed, and the lower end shall extend 300 mm to 500 mm into the bottom of the bored pile hole. The pipe shall be lowered and installed section by section. The inner diameter of the steel cage shall be at least 100 mm larger than the outer diameter of the pipe joint.

[0103] S9. Pouring concrete

[0104] During this step, continuous pouring is performed using the conduit method. Concrete strength should be configured according to the design strength grade, with a slump of 180mm-220mm. The top elevation of the cast-in-place pile should be at least 0.8m-1.0m higher than the design elevation to ensure concrete strength at the top of the pile.

[0105] Step S9 includes the following steps:

[0106] Step 9.1: During the first pouring of concrete, ensure that the bottom end of the conduit is buried 0.8m-1.3m into the concrete; at the same time, take samples of the concrete and perform standard curing.

[0107] Step 9.4: As the volume of concrete pouring increases, lift and remove the conduit in a timely manner, measure the rising height of the concrete in real time, and control the buried depth of the conduit to 2m-6m below the concrete surface.

[0108] The bored pile reinforcement method for deep soft soil layers provided in this embodiment can effectively solve the engineering problems that the current bored pile hole wall reinforcement measures cannot effectively reinforce the hole wall when drilling holes in highly sensitive soft soil layers, resulting in hole collapse, necking, etc.

[0109] The present invention also provides a model for reinforcing deep and soft soil layers with cast-in-place piles. Figures 1 to 2 , including: data acquisition module, reinforcement thickness limit determination module, formula module and evaluation module,

[0110] The data acquisition module is configured to acquire horizontal displacement data of the hole diameter under different reinforcement thicknesses of the rotary bored pile in several typical hole diameter working conditions;

[0111] The reinforcement thickness limit determination module is configured to determine the upper limit h of the reinforcement thickness of the rotary bored piles in several typical aperture working conditions based on the aperture horizontal displacement data of the rotary bored piles at different reinforcement thicknesses in the several typical aperture working conditions. max and the lower limit of reinforcement thickness h min ;

[0112] The formula module is configured to calculate the upper limit h of the reinforced thickness of the bored pile according to the several typical hole diameter working conditions. max and the lower limit of reinforcement thickness, and fit the calculation formula of the optimal reinforcement thickness h of the bored pile in different hole diameter working conditions; that is, the specific implementation of this process can be: the upper limit of the reinforcement thickness h of the bored pile in several typical hole diameter working conditions is max and the lower limit of reinforcement thickness h min The data were used as input data, and the Origin software was used to fit the curve equation of the upper and lower limit reinforcement thicknesses, and the curve equation of the optimal reinforcement thickness h was obtained by solving the calculation.

[0113] The evaluation module is configured to calculate the optimal reinforcement thickness h of the bored piles in several typical hole diameter working conditions according to the calculation formula of the optimal reinforcement thickness h of the bored piles in different hole diameter working conditions, and compare it with the upper limit h of the reinforcement thickness of the bored piles in several typical hole diameter working conditions. max and the lower limit of reinforcement thickness h min For comparison, if the optimal reinforcement thickness of the bored pile in several typical hole diameter conditions meets h min ≤h≤h max , that is, the calculation formula for the optimal reinforcement thickness h of the bored pile in different hole diameter working conditions is established. Otherwise, re-acquire the data and perform formula fitting until the requirements are met. That is, the specific implementation of this process can be: if h calculated using the above fitting formula is greater than or equal to h determined by the above numerical analysis software, min Less than or equal to h determined by the above numerical analysis software max , indicating that the calculation formula for the optimal reinforcement thickness h is established. Otherwise, re-acquire the data and perform formula fitting until the requirements are met.

[0114] The present invention provides a model for reinforced cast-in-place piles in deep and soft soil layers, which obtains the horizontal displacement data of the hole diameter under different reinforcement thicknesses of the rotary bored cast-in-place piles in several typical hole diameter working conditions; based on the horizontal displacement data of the hole diameter under different reinforcement thicknesses of the rotary bored cast-in-place piles in several typical hole diameter working conditions, the upper limit h of the reinforcement thickness of the rotary bored cast-in-place piles in several typical hole diameter working conditions is determined. max and the lower limit of reinforcement thickness h min According to the upper limit of the reinforced thickness of the rotary bored pile in the typical aperture conditions h max and the lower limit of reinforcement thickness h min , the Boltzmann method is used to fit the calculation formula for the optimal reinforcement thickness h of rotary bored piles in different hole diameter working conditions; according to the calculation formula for the optimal reinforcement thickness h of rotary bored piles in different hole diameter working conditions, the optimal reinforcement thickness h of rotary bored piles in several typical hole diameter working conditions is calculated, and compared with the upper limit h of the reinforcement thickness of rotary bored piles in several typical hole diameter working conditions max and the lower limit of reinforcement thickness h min Make a comparison to determine whether it is necessary to re-acquire data of several typical aperture working conditions to fit the calculation formula.

[0115] The present invention provides a cast-in-place pile reinforcement method and model for deep, soft soil layers. It proposes that high-pressure rotary jet piles be used to pre-reinforce the soft soil layer around the pile hole. After the cement slurry solidifies and hardens, and a closed annular reinforcement zone is formed in the soft soil layer around the pile hole, a rotary drilling rig is used to drill the hole. At the same time, the horizontal displacement data of the rotary bored cast-in-place piles under different reinforcement thicknesses in several typical aperture working conditions are combined to master the optimal reinforcement thickness h of the rotary bored cast-in-place piles under different aperture working conditions. This information is fed back to the project site, truly achieving safe and efficient guidance for the graded filling of the roadbed and providing reference and reference for similar projects. In addition, because the cement soil strength in the reinforced area is very high, dry excavation can be used for construction, effectively avoiding the phenomenon of mudstone softening by water under specific geological conditions, which causes the rotary drilling rig to slip, clog, and stick at the bottom, thereby improving construction efficiency, reducing mud discharge, and providing theoretical guidance for actual projects.

[0116] Example 1

[0117] The following is an example using a 1m aperture working condition.

[0118] Step 1: Four typical working conditions with apertures of 0.6m, 0.8m, 1.0m, and 1.2m were selected;

[0119] Step 2: Use numerical analysis software to calculate different reinforcement thicknesses for each working condition and monitor the horizontal displacement of the hole wall;

[0120] Step 3: Considering the safety and economic aspects of the bored pile, determine the upper limit of the bored pile reinforcement thickness h max and the lower limit of reinforcement thickness h min , upper limit of reinforcement thickness h max is the maximum horizontal displacement of the hole wall x max , that is, x max Reinforcement thickness ≤10mm; lower limit of reinforcement thickness h min is the maximum horizontal displacement of the hole wall x max , that is, 15mm≤x max Reinforcement thickness ≤20mm.

[0121] For example, after calculating various reinforcement thicknesses for the 1m diameter working condition, it was found that when the thicknesses of 0.85m, 0.90m, 0.95m, and 1.00m were reinforced, the maximum horizontal displacements of the hole wall were 28.9mm, 15.3mm, 10.8mm, and 7.1mm, respectively. Therefore, the upper limit of the reinforcement thickness of the 1m diameter cast-in-place pile is h. max The lower limit of reinforcement thickness is 1.00m. min It is 0.90m.

[0122] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A model for reinforced cast-in-place piles in deep soft soil layers, characterized in that: The following steps are involved: Carry out preliminary construction on the construction site, including site leveling, pile position setting, and casing burial; The high-pressure jet-jet drill drills to the soft soil pre-reinforcement depth, then sprays cement into the soil at high pressure and lifts the drill rod at a preset speed to fully mix the cement slurry and soil particles. As the cement slurry solidifies, it forms a closed annular reinforcement zone in the soft soil layer around the pile hole, achieving pre-reinforcement of the soft soil layer. Carry out hole-forming construction and conduct quality acceptance of the holes; Carry out the construction of steel cage and steel conduit, and then pour concrete; The model of cast-in-place pile reinforcement includes: The data acquisition module is configured to acquire aperture horizontal displacement data of rotary bored piles with different reinforcement thicknesses in several preset typical aperture working conditions; The reinforcement thickness limit determination module is configured to determine the upper limit of the reinforcement thickness of the rotary bored piles in several typical aperture working conditions based on the aperture horizontal displacement data of the rotary bored piles at different reinforcement thicknesses in the said several typical aperture working conditions. and the lower limit of reinforcement thickness ; A formula module is configured to fit a calculation formula for the optimal reinforcement thickness h of the bored piles in different hole diameter working conditions based on the upper limit and lower limit of the reinforcement thickness of the bored piles in the several typical hole diameter working conditions; The evaluation module is configured to calculate the optimal reinforcement thickness h of the bored piles in several typical hole diameter working conditions according to the calculation formula of the optimal reinforcement thickness h of the bored piles in different hole diameter working conditions, and compare it with the upper limit and lower limit of the reinforcement thickness of the bored piles in several typical hole diameter working conditions until the optimal reinforcement thickness h is satisfied. .

2. A cast-in-place pile reinforcement model for deep soft soil layers according to claim 1, characterized in that: The pile position setting out comprises the following steps: According to the coordinate points of the pile on the design drawing, place the center position of the pile; Mark the pile position at the center point of the pile.

3. A cast-in-place pile reinforcement model for deep soft soil layers as claimed in claim 2, characterized in that: The casing embedding comprises the following steps: The casing is buried in a vertical position at the construction site, with the deviation between the center of the casing and the center line of the pile position not exceeding 20mm; the top of the casing is 0.3m-0.5m above the ground.

4. A cast-in-place pile reinforcement model for deep soft soil layers as claimed in claim 3, characterized in that: The hole forming construction comprises the following steps: After the pile position is verified to be correct and the casing is buried in accordance with the requirements, the drilling rig is put in place; the drilling rig is kept in a flat and vertical position to ensure that the pile hole is vertical; Use a rotary drilling rig to carry out hole drilling operations.

5. A cast-in-place pile reinforcement model for deep soft soil layers as claimed in claim 4, characterized in that: The quality inspection of the hole includes the following steps: Check the hole diameter, hole depth, verticality and sediment thickness separately.

6. A cast-in-place pile reinforcement model for deep soft soil layers as claimed in claim 5, characterized in that: The construction of steel cage and steel conduit includes the following steps: The annular stirrups are connected to the main reinforcement by welding, and the spiral stirrups are connected to the main reinforcement by tying and welding; the width of the steel bar lap weld is not less than 0.7d, and the thickness of the lap weld is not less than 0.3d; the reinforcing hoops are set on the outside of the main reinforcement, and the lifting point of the steel cage is set at the reinforced stirrup position; the pile end grouting pipe and the steel cage are fixed by tying or welding and are evenly arranged; the top of the grouting pipe is 200mm above the ground, the pipe mouth is closed, and the lower end extends into the bottom of the bored pile hole 300mm-500m, and the guide tube is lowered section by section and installed.

7. A cast-in-place pile reinforcement model for deep soft soil layers according to claim 6, characterized in that: Protective layer pads are set on the steel cage to ensure the thickness of the protective layer, and the number of protective layer pads set for each section of the steel cage is not less than 2 groups. When the length is greater than 12m, an additional group is added in the middle, with no less than 3 blocks in each group, and they are evenly distributed on the main reinforcement of the same section.

8. A cast-in-place pile reinforcement model for deep soft soil layers as claimed in claim 1, characterized in that: Pouring concrete involves the following steps: When continuous pouring is done using the conduit method, ensure that the bottom of the conduit is buried 0.8m-1.3m into the concrete for the first pouring. As the volume of concrete pouring increases, the guide tube is intermittently lifted and removed to keep the buried depth of the guide tube 2m-6m below the concrete surface; The top elevation of the cast-in-place pile is 0.8m-1.0m higher than the design elevation to ensure the strength of the concrete at the top of the pile.

9. A cast-in-place pile reinforcement model for deep soft soil layers according to claim 8, characterized in that: The numerical range of the slump of the concrete is 180mm-220mm.

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