Method for solving problem of reduction of bearing capacity of pile foundation caused by upward floating of tubular pile
By forming a cement layer at the bottom of the pile and cutting and replacing the soil at the bottom of the pile with the triple pipe system, the problem of decreasing pile foundation bearing capacity caused by the floating of the pipe pile is solved, and efficient and low-cost pile foundation reinforcement effect is achieved.
Patent Information
- Application Number
- CN202510392990.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-31
- Publication Date
- 2025-07-18
AI Technical Summary
The prior art lacks effective construction methods when the pile foundation bearing capacity decreases, especially in underground structures or areas that cannot be reached.
By forming a cement layer at the bottom of the pile, high-pressure water, air and cement slurry are pumped into the bottom of the pile using a triple pipe system, cutting and replacing the soil at the bottom of the pile to form a high-strength cement layer to improve the bearing capacity of the pile foundation.
It realizes efficient and low-cost pile foundation reinforcement in complex soil layers, and is suitable for narrow or deep underground structures, improving the load-bearing capacity and construction success rate of pile foundations.
Smart Images
Figure CN120331316A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of foundation engineering, and particularly relates to a method for solving the problem of the decline in the bearing capacity of pile foundations caused by the floating of pipe piles. Background Art
[0002] The pipe piles in general buildings refer to high-strength precast concrete piles made by using prestressing technology and centrifugal forming technology, and they are hollow inside. During the construction of pipe piles, the problem of pipe pile floating easily occurs, resulting in a decline in the bearing capacity of the entire pile. Especially in hard plastic clay, the traction force of the soil mass is greater. When the buoyancy and traction force are greater than the pile gravity, the pile will float. After floating, a suspended area of the original soil layer of the bearing stratum will be formed within a certain range at the bottom end of the pile, and its supporting force is smaller than that of the original soil layer, causing the bearing capacity of the pile to decline.
[0003] Currently, for the problem of the decline in the bearing capacity of pile foundations caused by the floating of pipe piles in construction projects, the main solutions in the prior art are re-pressing and re-drilling methods. Use a static pile press to reapply pressure to press the pile back to the designed depth or use a pile driver to re-hammer the floating pile, or use the re-drilling method to "hammer" the pile back to its original position by the impact force. However, for building projects with basements or underground structures, when the top of the pipe pile is buried in the underground soil mass or in an area where the pile driving equipment cannot reach, the traditional pile re-drilling and re-pressing machinery will lack construction space and cannot be used, and cannot effectively solve the problem of the decline in bearing capacity caused by the floating of pile foundations.
[0004] Therefore, there is an urgent need for a method to solve the problem of the decline in the bearing capacity of pile foundations caused by the floating of pipe piles. Summary of the Invention
[0005] The purpose of this application is to solve the problem of the decline in the bearing capacity of the pile after the pile foundation floats in the prior art. Therefore, the present invention provides a method for solving the decline in the bearing capacity of pile foundations caused by the floating of pipe piles. By forming a cement layer at the bottom end of the pile, the original soil layer is replaced by the cement layer to improve the bearing capacity of the entire pile.
[0006] To achieve the above purpose, the present invention provides a method for solving the decline in the bearing capacity of pile foundations caused by the floating of pipe piles. The pile foundation reinforcement is carried out on the floating pile through cement slurry. The steps of the pile foundation reinforcement include:
[0007] S1: Drill a drill bit into the lower end of the pipe pile through the hole in the center of the pipe pile. The drill bit is provided with a triple pipe, and the triple pipe includes a high-pressure water pipe, a high-pressure air pipe, and a high-pressure grouting pipe;
[0008] S2: Pump clear water into the bottom of the pipe pile through the high-pressure water pipe and the high-pressure grouting pipe at the same time, and pump compressed air into the bottom of the pipe pile through the high-pressure air pipe;
[0009] Meanwhile, the drill bit reciprocates to cut the upper and lower soils at the end of the pipe pile within the range of 3 times the pipe pile diameter above the lower end of the pipe pile and 3 times the pipe pile diameter below the lower end of the pipe pile;
[0010] S3: After cutting is completed, close the triple pipe and insert the drill bit to a position 3 times the pipe pile diameter below the end of the pipe pile;
[0011] S4: Close the high-pressure air pipe and the high-pressure water pipe, and pump cement slurry into the bottom of the pipe pile through the high-pressure grouting pipe for high-pressure grouting;
[0012] S5: After grouting is completed, close the triple pipe and remove the drill bit. After the cement slurry hardens, the reinforcement of the pile foundation is completed.
[0013] The present invention uses existing triple-pipe double-high-pressure jet grouting equipment to spray high-pressure water, high-pressure air, and high-pressure cement slurry at the pile bottom in a certain order, replacing the original soil mixed zone of the bearing layer formed at the bottom of the pile with high-concentration cement slurry. After the cement slurry hardens, it forms an integral body with the pipe pile. In addition, during the hardening process of the cement slurry, it also bites with the surrounding soil layers, fixing the pipe pile above the cement slurry.
[0014] Specifically, during the process of flushing with the high-pressure water pipe, water and tiny particles emerge from the holes at the top of the pipe and are then pumped away by the pump; at the same time, the high-pressure water and air stir the soil within a certain range at the bottom of the pile into slurry. The slurry can shield the groundwater gaps around, simplify the complex underground soil layer environment, stir it into slurry, and at the same time, due to the friction force at the edge of the pile, the pipe pile will not sink in the slurry. After that, when the cement slurry is pumped in through the high-pressure grouting pipe, due to the high density of the cement, the original slurry in the pipe will be discharged to the upper surface of the pipe pile, and finally the voids are filled with cement to achieve the purpose of replacing the slurry with cement.
[0015] The compressive strength of the cement slurry reaches or exceeds that of the original soil, so it can play a role in strengthening the pile tip bearing layer and improving the bearing capacity of the pipe pile.
[0016] Specifically, in step S2, compressed air is pumped in, which can carry out the fine particles in the original soil layer by air, cut and stir the soil into slurry, and make preparations for the later filling of cement slurry;
[0017] In step S4, the high-pressure air pipe and the high-pressure water pipe are closed to prevent the air bubbles from carrying out the fine particles in the cement slurry and prevent the water from affecting the concentration of the cement slurry, thereby ensuring the strength of the cement slurry.
[0018] The present invention occupies a small space and only needs to prepare the installation space for the drill rig and the water tanks for storing clean water and cement slurry, and can construct the pipe piles in narrow or deep underground structures. The present invention directly pumps the cement slurry into the bottom of the pile through a high-pressure water pump, with low cost, high construction efficiency, and good fixing effect.
[0019] In some embodiments, the method of high-pressure grouting is as follows: Insert the drill pipe into the position 3 times the pile diameter below the end of the pipe pile, turn on the high-pressure grouting pump to perform in-situ spraying of slurry. After the in-situ spraying is completed, spray the slurry while lifting upward. After the drill bit reaches the position 3 times the pile diameter above the pile end of the pipe pile, insert the drill bit into the position 3 times the pipe diameter below the pile end again to perform the second in-situ spraying of slurry. After the second in-situ spraying of slurry is completed, spray the slurry while lifting upward. After reaching the position 3 times the pile diameter above the pile end of the pipe pile again, turn off the high-pressure grouting pump to complete the high-pressure grouting process.
[0020] Using the above technical method, after the cement slurry is pumped into the pile end, due to the large weight of the cement slurry, it can squeeze open the original slurry. Through multiple round trips of the triple tube, the cement slurry formed at the lower end of the pile body can fully cover the periphery of the pile end. After the cement slurry hardens, a dense cement block is formed, and the cement block has greater compressive strength, thereby providing more support for the pile.
[0021] In some embodiments, before the pile foundation is reinforced, low-strain testing is performed on the pipe pile to determine whether there is a phenomenon of welded joint detachment at the joint of the pipe pile.
[0022] This process can determine whether the pile is broken at a certain point. If the pile is broken somewhere in the middle or there is a phenomenon of welded joint detachment at the joint, then it is possible that the upper part of the broken part has floated. Even if the bottom of the pile is reinforced, the upper part of the broken part still cannot provide sufficient bearing capacity. Therefore, for the piles with broken pile bodies, they need to be demolished and re-arranged, and this scheme cannot be used for strengthening.
[0023] In some embodiments, the triple tube further includes a water-air nozzle and a cement slurry nozzle;
[0024] The high-pressure water pipe and the high-pressure air pipe share a water outlet hole, and high-pressure water and high-pressure air are sprayed out from the water-air nozzle together. The cement slurry nozzle is located below the water-air nozzle and sprays downward at an angle of 45° obliquely downward.
[0025] Using the above technical solution, water and air are sprayed out from the same hole. First, after the air and water are fully mixed, the bubbles can discharge the tiny particles in the water during the upward floating process, helping to form the slurry faster. Second, the water with high-pressure bubbles has stronger cutting ability and stronger stirring ability.
[0026] In some embodiments, an early strength agent is added to the cement slurry to accelerate the setting speed of the cement and prevent it from being affected by groundwater or other disturbances during the setting process.
[0027] It further includes a drill pipe, and the drill bit is arranged at the end of the drill pipe. In step S1, scale lines are provided on the drill pipe, and when the drill bit reaches the position 3 times the pile diameter above the pile end, the work starts.
[0028] In some embodiments, in step S2: the water pressure of the high-pressure water pipe ≥ 35 MP, and the water pressure in the high-pressure grouting pipe ≥ 20 MP.
[0029] With the above technical solution, through the high-pressure water pipe and the high-pressure grouting pipe, the groundwater gaps, cracked soil layers, and tiny holes in the soil at the bottom of the pile are broken into mud by double high pressure, blocking the entry of groundwater and preparing for subsequent cement grouting.
[0030] In some embodiments, in step S4, the fineness requirement of the cement slurry is that the surface area is not less than 350 m² / kg; the water-cement ratio is 1:1, and the mass percentage of the cement consumption per single pile is 35% - 40% (specifically referring to the cement consumption within the cylinder with a range of three times the pile diameter above and below the bottom of the pile).
[0031] Generally speaking, compared with the prior art, the beneficial effects of the present invention are as follows: through the triple tube, the soil layer within a certain range at the bottom of the pile is first treated. Through high-pressure water, the complex soil layer holes, soil layer gaps, or groundwater channels underground are cut and mixed into mud, and then the cement slurry is poured into it to replace the mud therein. After the cement hardens, it provides higher supporting force. The present invention has low treatment cost, is applicable to various complex soil layers, has a high success rate, and has a relatively short construction period.
[0032] Other features and corresponding beneficial effects of the present application are described in the following part of the specification, and it should be understood that at least some of the beneficial effects become obvious from the description in the specification of the present application. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] By reading the detailed description of the non-restrictive embodiments with reference to the following drawings, the present invention and its features, shape, and advantages will become more obvious. The same reference numerals indicate the same parts in all the drawings. The drawings are not drawn to scale, and the emphasis is on showing the gist of the present invention.
[0034] Figure 1 It is a schematic diagram of the pile end after pile end reinforcement in the embodiment of the present invention;
[0035] Description of the reference numerals:
[0036] 1, pipe pile; 2, drill bit; 21, drill pipe; 3, cement slurry. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0037] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.
[0038] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "vertical", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present application 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 construed as a limitation of the present application. In addition, unless otherwise clearly specified and limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.
[0039] To make the purpose, technical solution and advantages of the present application clearer, the embodiments of the present application will be further described in detail below in conjunction with the accompanying drawings.
[0040] Embodiment
[0041] See Figure 1 , a method for solving the decline of pile foundation bearing capacity caused by the floating of pipe piles. The floating pipe piles 1 are reinforced by cement slurry 3. The steps of pile foundation reinforcement include:
[0042] S1: Drill the drill bit 2 into the lower end of the pipe pile 1 through the hole in the center of the pipe pile 1. The drill bit 2 is provided with a triple pipe, and the triple pipe includes a high-pressure water pipe, a high-pressure air pipe and a high-pressure grouting pipe;
[0043] S2: Pump clear water into the bottom of the pipe pile 1 through the high-pressure water pipe and the high-pressure grouting pipe at the same time, and pump compressed air into the bottom of the pipe pile 1 through the high-pressure air pipe;
[0044] At the same time, the drill bit reciprocates within the range of 3 times the pipe pile diameter above the lower end of the pipe pile 1 and 3 times the pipe pile diameter below the lower end of the pipe pile 1 to cut the upper and lower soil bodies at the end of the pipe pile;
[0045] S3: After cutting is completed, close the triple pipe and insert the drill bit 2 into the position 3 times the pipe pile diameter below the end of the pipe pile 1;
[0046] S4: Close the high-pressure air pipe, close the high-pressure water pipe, and pump cement slurry 3 into the bottom of the pipe pile 1 through the high-pressure grouting pipe for high-pressure grouting;
[0047] S5: After grouting is completed, close the triple pipe and remove the drill bit. After the cement slurry 3 hardens, the pile foundation reinforcement is completed.
[0048] The interior of the original pipe pile 1 and the lower end of the pipe pile 1 are filled with soil. After the pipe pile 1 floats, an overhead area of a certain range is formed below the pipe pile 1. The bearing capacity of the overhead area is small, and the soil layer in the overhead area has complexity and uncertainty, making it difficult to accurately judge. Therefore, in the prior art, there has always been a lack of a convenient and highly successful solution to the problem of the floating of the pipe pile 1. In response to this, the solution of this embodiment is to fill the water and soil mixed suspended area of the original soil layer and the pile foundation with high-concentration cement slurry 3 and make its strength reach or exceed that of the original soil, so as to achieve the effect of strengthening the pile tip bearing layer and improving the pile tip bearing capacity.
[0049] Specifically, the construction method is as follows:
[0050] 1. After excavating the soil to the pile top elevation position, measure and record the data of the pile top elevation of the original pipe pile 1, and compare it with the construction record table of the original pipe pile 1 to determine the floating piles and the corresponding floating heights.
[0051] 2. Conduct a low-strain test on the pipe pile 1 to judge whether there is a phenomenon of weld detachment at the joint of the pipe pile 1. If necessary, use in-hole camera imaging for confirmation.
[0052] 3. Determine the type selection of the pipe pile foundation, geological conditions, the location of the pile tip, etc. at the project location, and analyze the reasons for the floating of the pile foundation. This solution is applicable to the floating caused by the buoyancy and traction force of the pile body being greater than the gravity of the pile body due to soil.
[0053] 4. Select a suitable triple-tube drill bit and cement slurry. Specifically: The drill bit is mainly an alloy steel drill bit. Requirements for some nozzles of the nozzle sleeve: The high-pressure water pipe and the high-pressure air pipe share a water outlet hole, and high-pressure water and high-pressure air are ejected together from the water-air nozzle. The diameter of the water-air nozzle is 2.0 - 3.0 mm; the cement slurry nozzle is located below the water-air nozzle and sprays downward at an angle of 45° downward, and the nozzle diameter is 4 mm.
[0054] The cement slurry 3 uses P42.5 ordinary Portland cement, and the fineness requirement of the cement is that the surface area is not less than 350 m² / kg. The water-cement ratio is 1:1, and the mass percentage of the single-pile cement consumption is 35% - 40% (the proportion of cement within three times the pipe diameter below and above the lower end of the pipe pile).
[0055] 5. Move the drill rig to the position of the pipe pile 1, and accurately position the drill pipe 21 to ensure that the drill bit 2 vertically drills into the interior of the pipe pile 1.
[0056] 6. Extend the drill bit to a position 3 times the pile diameter above the lower end of the pipe pile 1.
[0057] 7. Place the high-pressure water pipe and the high-pressure grouting pipe into the clean water tank simultaneously. Turn on the high-pressure water pump and the high-pressure grouting pump, and monitor the water jet cutting the soil. The pressure of the water jet of the water pump is ≥35MP, and the pressure of the high-pressure grouting pump is ≥20MP. Reciprocate 2 times to cut the soil above and below the pile tip within the range of 3 times the pile diameter above the pile tip and 3 times the pile diameter below the pile tip. The lifting speed is carried out at 7 - 10 cm / min. After cutting the soil, turn off the high-pressure water pump and the high-pressure grouting pump.
[0058] 8. Keep the high-pressure water pipe and the high-pressure air jet pipe closed. Place the high-pressure grouting pipe into the cement slurry pool. Through the high-pressure grouting pipe, spray cement slurry 3 to the lower end of the pipe pile 1. Insert the drill rod 21 into the position 3 times the pile diameter below the pile tip. Turn on the high-pressure grouting pump and monitor the grouting time. The grouting pressure is 20 - 30MP, and grout in place for 3 minutes. Lift and spray grout upward, and the lifting speed is carried out at 7 - 10 cm / min. After the drill bit 2 reaches the position 3 times the pile diameter above the pile tip of the pipe pile, insert the drill rod 21 into the position 3 times the pile diameter below the pile tip again, grout in place for 3 minutes, lift and spray grout upward, and the lifting speed is carried out at 7 - 10 cm / min. After reaching the position 3 times the pile diameter above the pile tip again, turn off the high-pressure grouting pump to complete the high-pressure grouting.
[0059] 9. Take out the drill bit 2 and wait for the cement slurry to solidify. After the floating pipe pile foundation reinforcement is completed for 28 days, carry out the static load test of the pile foundation to judge whether the bearing capacity meets the requirements.
[0060] The above pile foundation reinforcement method has been verified by practice to have a high success rate and is easy to operate.
[0061] Those skilled in the art should understand that those skilled in the art can achieve variations in combination with the prior art and the above embodiments, which will not be elaborated here. Such variations do not affect the essence of the present invention and will not be elaborated here.
[0062] The above describes the preferred embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments. The equipment and structures not described in detail should be understood to be implemented in the ordinary way in the art; Any person skilled in the art, without departing from the scope of the technical solution of the present invention, can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above, or modify it into an equivalent embodiment with equivalent changes, which does not affect the essence of the present invention. Therefore, all contents that do not depart from the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention, still fall within the scope of the protection of the technical solution of the present invention.
Claims
1. A method for solving the problem of the decrease in the bearing capacity of a pile foundation caused by the floating of pipe piles, characterized in that, Pile foundation reinforcement is carried out on the floating pipe piles through cement slurry. The steps of the pile foundation reinforcement include: S1: Drill the drill bit (2) into the lower end of the pipe pile (1) through the hole in the center of the pipe pile (1). The drill bit (2) is provided with a triple pipe, and the triple pipe includes a high-pressure water pipe, a high-pressure air pipe, and a high-pressure grouting pipe; S2: Pump clear water into the bottom of the pipe pile (1) through the high-pressure water pipe and the high-pressure grouting pipe at the same time, and pump compressed air into the bottom of the pipe pile (1) through the high-pressure air pipe; At the same time, the drill bit (2) reciprocates within the range of 3 times the pipe pile diameter above the lower end of the pipe pile (1) and 3 times the pipe pile diameter below the lower end of the pipe pile (1) to cut the soil above and below the end of the pipe pile (1); S3: After cutting is completed, close the triple pipe and insert the drill bit (2) into a position 3 times the pipe pile diameter below the end of the pipe pile (1); S4: Close the high-pressure air pipe and the high-pressure water pipe, and pump cement slurry (3) into the bottom of the pipe pile (1) through the high-pressure grouting pipe for high-pressure grouting; S5: After grouting is completed, close the triple pipe and remove the drill bit (2). After the cement slurry (3) hardens, the pile foundation reinforcement is completed.
2. A method for solving the decline of pile foundation bearing capacity caused by the floating of pipe piles according to claim 1, characterized in that, In step S4, the method of high-pressure grouting is: insert the drill pipe (21) into a position 3 times the pile diameter below the end of the pipe pile (1), start the high-pressure grouting pump for in-situ spraying. After the in-situ spraying is completed, spray while lifting upwards. After the drill bit (2) reaches a position 3 times the pile diameter above the pile end of the pipe pile (1), insert the drill bit (2) into a position 3 times the pipe diameter below the pile end again for the second in-situ spraying. After the second in-situ spraying is completed, spray while lifting upwards. After reaching a position 3 times the pile diameter above the end of the pipe pile (1) again, close the high-pressure grouting pump to complete the high-pressure grouting process.
3. A method for solving the decline of pile foundation bearing capacity caused by the floating of pipe piles according to claim 1, characterized in that, Before pile foundation reinforcement, low-strain detection is carried out on the pipe pile (1) to judge whether there is a phenomenon of weld detachment at the joint of the pipe pile (1).
4. A method for solving the decline of pile foundation bearing capacity caused by the floating of pipe piles according to claim 1, characterized in that, The triple pipe further includes a water-air nozzle and a cement slurry nozzle; The high-pressure water pipe and the high-pressure air pipe share a water outlet hole, and high-pressure water and high-pressure air are ejected from the water-air nozzle together. The cement slurry nozzle is located below the water-air nozzle and sprays downward at an angle of 45° obliquely downward.
5. A method for solving the decline of pile foundation bearing capacity caused by the floating of pipe piles according to claim 1, characterized in that, An early strength agent is added to the cement slurry (3).
6. A method for solving the decline of pile foundation bearing capacity caused by the floating of pipe piles according to claim 1, characterized in that, It further includes a drill pipe (21), and the drill bit (2) is arranged at the end of the drill pipe (21). In step S1, scale lines are arranged on the drill pipe (21), and when the drill bit (2) reaches a position 3 times the pile diameter above the pile end, work starts.
7. A method for solving the decline in pile foundation bearing capacity caused by the floating of pipe piles according to claim 1, characterized in that, In step S2: the water pressure of the high-pressure water pipe ≥ 35MP, and the water pressure in the high-pressure grouting pipe ≥ 20MP.
8. A method for solving the decline in pile foundation bearing capacity caused by the floating of pipe piles according to claim 1, characterized in that, In step S4, the fineness requirement of the cement slurry (3) is that the surface area is not less than 350 m² / kg; the water-cement ratio is 1:1, and the mass percentage of the single-pile cement consumption is 35% - 40%.