Synchronous grouting type pile sinking method suitable for high-frequency vibration pile sinking

Abstract

According to the synchronous grouting type pile sinking method suitable for high-frequency vibration pile sinking, through synchronous grouting, the strength of the surrounding soil body is rapidly recovered, and the bearing capacity of the soil body is provided; the device does not affect the existing pile sinking process and device, is suitable for application under different pipe diameters and different geological conditions, and is high in applicability. Due to the design of the check valve, grout backflow when grouting is stopped is prevented, and the grouting efficiency is improved. According to the steel pipe pile end grouting device capable of being used for high-frequency vibration pile sinking and the pile sinking method, synchronous grouting is conducted on the soil body area around the pile and under the pile with structural damage, the bearing capacity of a pile foundation is rapidly improved, and therefore the design requirement is met.

Description

Technical Field

[0001] The invention relates to a synchronous grouting pile driving method suitable for high-frequency vibration pile driving. Background Art

[0002] Steel pipe piles have the advantages of high strength, ability to withstand large impact forces, easy penetration of hard soil layers, high bearing capacity, ability to withstand large horizontal forces, and adjustable pile length. They are widely used in foundation engineering, municipal engineering, and port engineering. With the large-scale construction of urban elevated expressways in recent years, high-frequency resonance-free pile driving has become popular among practitioners due to its advantages such as low environmental disturbance and high work efficiency. High-frequency vibration pile driving is achieved by rotating one or more pairs of eccentric blocks in an electrically or hydraulically driven pile hammer. The centrifugal forces generated thereby offset each other in the horizontal direction and superimpose each other in the vertical direction to form a simple harmonic excitation force to sink the pile. A cyclic dynamic load is applied to the top of the pile. There is no vibration output during the start-up and stop phases to avoid resonance, which greatly reduces the impact of soil vibration and reduces the soil's resistance to the pile, allowing the pile to sink smoothly to the designed elevation.

[0003] The use of high-frequency, resonance-free pile sinking technology can cause structural damage to the soil surrounding the pile and temporarily lose its strength. This can greatly improve pile sinking efficiency, but a large number of practices have found that the bearing capacity of the pile decreases significantly after sinking and cannot be restored for a long time, which greatly affects the progress of the project. Grouting on the side or end of the pile is usually used to improve the bearing capacity of the pile foundation. However, there are currently few mature grouting processes for steel pipe piles driven by high-frequency vibration. Grouting from the pile core to the pile end is affected by soil plugging, making it difficult to insert the grouting pipe to the bottom of the steel pipe pile. In addition, the soil layer corresponding to the pile end is deeper, and the external soil resistance during grouting is greater. During each period of withdrawing the pump, replacing the pump, and stopping grouting, the external slurry mixed with some soil easily flows back into the grouting pipe, causing the grouting pipe to be blocked and affecting the grouting effect. Summary of the Invention

[0004] The object of the present invention is to provide a synchronous grouting pile driving method suitable for high-frequency vibration pile driving.

[0005] To solve the above problems, the present invention provides a synchronous grouting pile driving method suitable for high-frequency vibration pile driving, comprising:

[0006] Before sinking the pile, set the through holes at intervals on the upper part of the steel pipe at the pile end of the steel pipe pile;

[0007] Fix two pile end grouting devices at intervals on the inner wall of the pile end steel pipe, and sleeve the pile side grouting port connected to the pile end grouting device into the through hole, with the opening of the grouting port located on the outer side wall of the pile end steel pipe; fix the pile end grouting pipe on the inner wall of the pile end steel pipe between the two pile side grouting devices; arrange a pile side grouting interface on the upper side of the center of each hollow steel pipe, connect one end of the pile side grouting pipe to the pile side grouting interface, and arrange the pile end grouting pipe between the two ends of the two hollow steel pipes;

[0008] Connect the other end of the pile side grouting pipe of the pile side grouting branch of the grouting equipment; connect the pile end grouting pipe to the pile end grouting branch of the grouting equipment;

[0009] The high-frequency resonance-free process is used to sink the pile end steel pipe. When the sinking depth of the pile end steel pipe exceeds 5 meters, the grouting equipment is started, and the pile side grouting branch is opened to start pile side grouting.

[0010] When the pile end steel pipe is sunk, turn off the grouting equipment and start connecting the second section and above steel pipe piles on the upper part of the pile end steel pipe;

[0011] After the pile sinking is completed, close the pile end grouting branch of the grouting equipment, and open the pile end grouting branch to start pile end grouting.

[0012] Furthermore, in the above method, before sinking the pile, through holes are provided at intervals on the upper portion of the steel pipe at the pile end of the steel pipe pile, including:

[0013] Drill holes at an angle of 30° at the center of the steel pipe at the pile end of the steel pipe pile to form through-holes.

[0014] Furthermore, in the above method, each pile end grouting device is a hollow steel pipe with an arc shape; the arc angle is 170°; and pile side grouting ports are arranged on the outside of the hollow steel pipe every 30°.

[0015] Furthermore, in the above method, a check valve is installed at the connection between the hollow steel pipe and the pile side grouting port.

[0016] Furthermore, in the above method, when the pile end steel pipe is sunk to a depth of more than 5 meters, the grouting equipment is started, and the pile side grouting branch is opened to start pile side grouting, including:

[0017] The grouting pressure of the pile side grouting branch is set to P, which can be obtained according to the following formula:

[0018] When the pile depth is less than 10m, P = ρgh + 0.1MPa, where ρ is the average saturated density of the soil; h is the pile depth; g is the acceleration of gravity;

[0019] When the pile driving depth is greater than 10m, P = ρgh + 0.2Mpa.

[0020] Furthermore, in the above method, when the pile end steel pipe is sunk, the grouting equipment is turned off, and the second section and above of other steel pipe piles are connected to the upper part of the pile end steel pipe, including:

[0021] Pre-weld the corresponding pile side grouting pipes and pile end grouting pipes in other steel pipe piles with two or more sections;

[0022] Use high-pressure nylon pipes to connect the pile side grouting pipe and the upper end of the pile end grouting pipe of the pile end steel pipe with the lower ends of the pile side grouting pipe and the pile end grouting pipe of two or more other steel pipe piles respectively;

[0023] Open the pile end grouting branch of the grouting equipment and start grouting;

[0024] Connect the first section of steel pipe piles and the second section and above steel pipe piles by welding; then continue sinking the piles, start the grouting equipment simultaneously, open the pile side grouting branch and start pile side grouting.

[0025] Furthermore, in the above method, the lengths of the pile side grouting pipes and pile end grouting pipes in two or more sections of other steel pipe piles are 10 cm shorter than the lengths of the two or more sections to which they belong.

[0026] Furthermore, in the above method, after the pile sinking is completed, the pile end grouting branch of the grouting equipment is closed, and the pile end grouting branch is opened to start the pile end grouting, including:

[0027] The grouting pressure of the pile end grouting branch is P, which is obtained according to the following formula:

[0028] P = ρgh + 0.25 MPa, where ρ is the average saturated density of the soil; h is the pile driving depth; and g is the acceleration of gravity.

[0029] Furthermore, in the above method, the length of the high-pressure nylon tube is 15 cm.

[0030] Furthermore, in the above method, the pile side grouting pipe is made of a steel pipe.

[0031] Compared with the existing technology, the present invention rapidly restores the surrounding soil strength and increases soil bearing capacity through synchronous grouting. The present invention does not affect existing pile driving processes and equipment and is suitable for applications with different pipe diameters and different geological conditions, with strong applicability. A check valve design prevents slurry backflow when grouting stops, thereby improving grouting efficiency. The present invention can be used for high-frequency vibration pile driving, including a steel pipe pile end grouting device and pile driving method. Synchronous grouting is performed on structurally damaged soil areas around and beneath the piles, rapidly increasing the bearing capacity of the pile foundation to meet design requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of a pile tip grouting device according to an embodiment of the present invention;

[0033] Figure 2 1 is a side view of a steel pipe at a pile end of a steel pipe pile according to an embodiment of the present invention;

[0034] Figure 3 1 is a top view of a steel pipe at a pile end of a steel pipe pile according to an embodiment of the present invention;

[0035] Figure 4 1 is a schematic diagram of the installation of the upper steel pipe of a steel pipe pile according to an embodiment of the present invention;

[0036] 1—Hollow pipe for pile side grouting; 2—Grouting port for pile side; 3—Grouting pipe at pile end; 4—Grouting interface for pile side; 5—Steel pipe at pile end of steel pipe pile; 6—Through hole; 7—Grouting pipe at pile side; 8—Grouting branch at pile side; 9—Grouting branch at pile end; 10—Grouting equipment; 11—Upper steel pipe of steel pipe pile. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] like Figure 1 As shown, the present invention provides a synchronous grouting pile driving method suitable for high-frequency vibration pile driving, comprising:

[0039] Step S1, such as Figure 1 、 2 As shown in FIG3 , steel pipe pile drilling: before sinking the pile, through holes 6 are set at intervals on the upper portion of the steel pipe 5 at the end of the steel pipe pile;

[0040] Preferably, Figure 2 and 3 This is a structural diagram of the pile end steel pipe 5 of the steel pipe pile. The steel pipe 5 is made of steel. A pair of through holes 6 are drilled at 30° intervals at the center height of the pile end steel pipe 5. The diameter of the pair of through holes is slightly larger than the outer diameter of the pile side grouting port 2 of the pile end grouting device 1.

[0041] Step S2, fixing the grouting device: match the pile side grouting port 2 with the drilling position, fix the two pile end grouting devices 1 on the inner wall of the pile end steel pipe at intervals, ensure the connection is firm by welding, and sleeve the pile side grouting port 2 connected to the pile end grouting device 1 into the through hole 6, with the opening of the grouting port 2 located on the outer side wall of the pile end steel pipe 5; fix the pile end grouting pipe 3 on the inner wall of the pile end steel pipe 5 between the two pile side grouting devices 1 by welding;

[0042] Preferably, each pile end grouting device 1 is a circular arc-shaped hollow steel pipe;

[0043] like Figure 1As shown, the pile end grouting device 1 is made of steel. The outer diameter of the hollow steel pipe is 3cm-5cm and the wall thickness is 2-3mm. The entire hollow steel pipe is in an arc shape with an arc angle of about 170°. The outer diameter of the hollow steel pipe is slightly smaller than the inner diameter of the steel pipe pile, and is as large as possible while ensuring the internal fixation of the steel pipe pile. Pile side grouting ports 2 are arranged every 30° on the outside of the hollow steel pipe 1. The length of the pile side grouting ports is consistent with the wall thickness of the steel pipe pile. A check valve is installed at the connection between the grouting hollow pipe 1 and the pile side grouting port 2 to prevent external soil from entering the hole during pile sinking and to prevent external slurry mixed with part of the soil from flowing back into the hole when the pump is removed or replaced to stop grouting, causing blockage.

[0044] Preferably, the upper ends of the pile side grouting pipe 7 and the pile end grouting pipe 3 are about 5 cm lower than the top of the pile end steel pipe.

[0045] A pile side grouting interface 4 is arranged on the upper side of the center of each hollow steel pipe, and an internal thread is provided in the pile side grouting interface 4. One end of the pile side grouting pipe 7 is connected to the pile side grouting interface 4 through the cooperation of the external thread on one end of the pile side grouting pipe 7 and the internal thread of the pile side grouting interface 4;

[0046] A pile end grouting pipe 3 is arranged between the two ends of the two hollow steel pipes, and the pile end grouting pipe 3 is made of a steel pipe;

[0047] Step S3, establishing the grouting system: connecting the other end of the pile side grouting pipe 7 to the pile side grouting branch 8 of the grouting equipment 10; connecting the pile end grouting pipe 3 to the pile end grouting branch 9 of the grouting equipment 10;

[0048] Step S4, pile sinking: The pile end steel pipe 5 is sunk using a high-frequency resonance-free process. When the sinking depth of the pile end steel pipe 5 exceeds 5 meters, the grouting equipment 10 is started, and the pile side grouting branch 8 is opened to start pile side grouting;

[0049] Preferably, the grouting pressure of the pile side grouting branch 8 is P, which can be obtained according to the following formula:

[0050] When the pile depth is less than 10m, P = ρgh + 0.1MPa, where ρ is the average saturated density of the soil. In the absence of geological data, 20 tons / m3 can be used. h is the pile depth (m); g is the acceleration due to gravity.

[0051] When the pile depth is greater than 10m, P = ρgh + 0.2MPa, where ρ is the average saturated density of the soil. In the absence of geological data, 20 tons / m3 can be used, and h is the pile depth (m);

[0052] Figure 4This is a schematic diagram of the grouting supply. Grouting equipment 10 has four or more grouting supply branches, each of which can be opened and closed freely, and the grouting pressure can be adjusted. The equipment connects the pile-side grouting branch 8 and the pile-end grouting branch 9. Grouting branches 8 and 9 are made of high-pressure hoses, one end of which is connected to the grouting equipment 10 and the other end is connected to the pile-side grouting pipe 7 and pile-end grouting pipe 3. The pile-side grouting pipe 7 is made of steel pipe.

[0053] Step S5, pipe pile connection: when the pile end steel pipe 5 is sunk, the grouting equipment 10 is turned off, and the second section and above of other steel pipe piles 11 are connected to the upper part of the pile end steel pipe 5;

[0054] Preferably, the steps for connecting the upper portion of the pile end steel pipe 5 to the second and subsequent steel pipe piles 11 are as follows:

[0055] 1) Grouting pipe welding: pre-weld two corresponding pile side grouting pipes 7 and pile end grouting pipes 3 in other steel pipe piles of the second section or more, and the positions are basically the same as the positions of the grouting pipes of the first section of the steel pipe pile. Preferably, the length of the pile side grouting pipes 7 and pile end grouting pipes 3 in other steel pipe piles of the second section or more is 10 cm shorter than the length of the second section or more, ensuring that both ends of the grouting pipes are retracted about 5 cm from the two ends of the two sections of the steel pipe pile.

[0056] 2) Grouting pipe connection: Use a high-pressure nylon tube of about 15 cm to connect the pile side grouting pipe 7 of the pile end steel pipe 5 and the upper end of the pile end grouting pipe 3 to the lower ends of the pile side grouting pipe 7 and pile end grouting pipe 3 of other steel pipe piles of the second section or above, respectively, to ensure that the connection is firm and watertight;

[0057] 3) Grouting test: Open the pile end grouting branch 8 of the grouting equipment 10 and start grouting to check whether there is leakage at the connection. If there is no leakage, close the grouting branch;

[0058] 4) Steel pipe pile connection: connect the first section of steel pipe pile and the second section and above steel pipe piles by welding; then continue sinking the piles, start the grouting equipment 10 synchronously, open the pile side grouting branch 8 and start pile side grouting.

[0059] In this way, the second and third sections of steel pipe piles and subsequent steel pipe pile operations are completed in the same steps until the piles are sunk to the specified depth.

[0060] Step S6: After the pile sinking is completed, the pile end grouting branch 8 of the grouting equipment 10 is closed, and the pile end grouting branch 9 is opened to start the pile end grouting. The grouting pressure of the pile end grouting branch 9 is P, which is obtained according to the following formula:

[0061] P=ρgh+0.25Mpa.

[0062] In summary, the present invention rapidly restores the surrounding soil strength and increases soil bearing capacity through synchronous grouting. The present invention does not affect existing pile driving processes and devices, is applicable to applications with different pipe diameters and different geological conditions, and has strong applicability. The check valve design prevents slurry backflow when grouting stops, thereby improving grouting efficiency. The present invention can be used for a steel pipe pile end grouting device and pile driving method for high-frequency vibration pile driving, and synchronously grouting is performed on the soil areas around and under the structurally damaged piles, rapidly improving the pile foundation bearing capacity to meet design requirements.

[0063] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0064] Obviously, those skilled in the art may make various changes and modifications to the invention without departing from the spirit and scope of the invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A synchronous grouting pile driving method suitable for high-frequency vibration pile driving, characterized in that: include: Before sinking the pile, set the through holes at intervals on the upper steel pipe of the pile end of the steel pipe pile; Two pile end grouting devices are fixed at intervals on the inner wall of the pile end steel pipe, and the pile side grouting port connected to the pile end grouting device is sleeved in the through hole, and the opening of the grouting port is located on the outer side wall of the pile end steel pipe; the pile end grouting pipe is fixed on the inner wall of the pile end steel pipe between the two pile side grouting devices; a pile side grouting interface is arranged on the upper side of the center of each hollow steel pipe, one end of the pile side grouting pipe is connected to the pile side grouting interface, and the pile end grouting pipe is arranged between the two ends of the two hollow steel pipes; Connect the other end of the pile side grouting pipe of the pile side grouting branch of the grouting equipment; connect the pile end grouting pipe to the pile end grouting branch of the grouting equipment; The high-frequency resonance-free process is used to sink the pile end steel pipe. When the sinking depth of the pile end steel pipe exceeds 5 meters, the grouting equipment is started, and the pile side grouting branch is opened to start the pile side grouting; When the steel pipe at the pile end is sunk, the grouting equipment is turned off and the second section and above of other steel pipe piles are connected to the upper part of the steel pipe at the pile end; After the pile sinking is completed, close the pile end grouting branch of the grouting equipment, and open the pile end grouting branch to start pile end grouting.

2. The synchronous grouting pile sinking method suitable for high-frequency vibration pile sinking as claimed in claim 1, characterized in that: Before sinking the pile, set the through holes at intervals on the upper steel pipe of the pile end of the steel pipe pile, including: Drill holes at an angle of 30° at the center height of the steel pipe at the pile end of the steel pipe pile to form through holes.

3. The synchronous grouting pile sinking method suitable for high-frequency vibration pile sinking as claimed in claim 1, characterized in that: Each pile end grouting device is a circular arc hollow steel pipe; the circular arc angle is 170°; and pile side grouting ports are arranged at intervals of 30° on the outer side of the hollow steel pipe.

4. The synchronous grouting pile sinking method suitable for high-frequency vibration pile sinking as claimed in claim 3, characterized in that: A check valve is arranged at the connection between the hollow steel pipe and the grouting port on the pile side.

5. The synchronous grouting pile driving method suitable for high-frequency vibration pile driving according to claim 1, characterized in that: When the pile end steel pipe sinking depth exceeds 5 meters, start the grouting equipment, open the pile side grouting branch and start the pile side grouting, including: The grouting pressure of the pile side grouting branch is set to P, which can be obtained according to the following formula: When the pile depth is less than 10m, P = ρgh + 0.1MPa, where ρ is the average saturated density of the soil; h is the pile depth; g is the acceleration of gravity; When the pile driving depth is greater than 10m, P=ρgh+0.2Mpa.

6. The synchronous grouting pile driving method suitable for high-frequency vibration pile driving according to claim 1, characterized in that: When the pile end steel pipe is sunk, turn off the grouting equipment and start connecting the second section and above steel pipe piles on the upper part of the pile end steel pipe, including: Pre-weld the corresponding pile side grouting pipes and pile end grouting pipes in other steel pipe piles in the second section or above; Use a high-pressure nylon pipe to connect the pile side grouting pipe and the upper end of the pile end grouting pipe of the pile end steel pipe with the lower ends of the pile side grouting pipe and the pile end grouting pipe of other steel pipe piles of the second section or above; Open the pile end grouting branch of the grouting equipment and start grouting; Connect the first section of steel pipe piles and the second section and above by welding; then continue sinking the piles, start the grouting equipment simultaneously, open the pile side grouting branch and start pile side grouting.

7. The synchronous grouting pile driving method suitable for high-frequency vibration pile driving as claimed in claim 6, characterized in that: The length of the pile side grouting pipe and pile end grouting pipe in other steel pipe piles with two sections or more is 10cm shorter than the length of the two sections or more to which they belong.

8. The synchronous grouting pile driving method suitable for high-frequency vibration pile driving as claimed in claim 1, characterized in that: After the pile sinking is completed, the pile end grouting branch of the grouting equipment is closed, and the pile end grouting branch is opened to start the pile end grouting, including: The grouting pressure of the pile end grouting branch is P, which is obtained according to the following formula: P=ρgh+0.25Mpa, where ρ is the average saturated density of the soil; h is the pile driving depth; and g is the acceleration of gravity.

9. The synchronous grouting pile sinking method suitable for high-frequency vibration pile sinking as claimed in claim 8, characterized in that: The length of the high-pressure nylon tube is 15 cm.

10. The synchronous grouting pile driving method suitable for high-frequency vibration pile driving according to claim 1, characterized in that: The pile side grouting pipe is made of steel pipe.

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