Loess tunnel base reinforcement composite multifunctional pile foundation and construction method

Abstract

The application discloses a loess tunnel base reinforcing composite multifunctional pile foundation and a construction method, and relates to the technical field of tunnel base reinforcement. The application discloses a loess tunnel base reinforcing composite multifunctional pile foundation and a construction method, and relates to the technical field of tunnel base reinforcement. The steel pipe pile comprises a steel pipe body, a reinforcing ring, a rectangular notch, a first limiting block, a conical head, a second limiting block, a conical sleeve, a through hole and a fastener. The cement soil compaction pile comprises a semicircular plate, a conical barb and a filling body. The application guarantees the safe bearing of the base reinforcing protection hole body structure, and guarantees that the cement soil compaction pile does not break during the construction period and the operation stage, thereby avoiding the collapsible settlement, guaranteeing the safe and reliable tunnel structure during the whole service life, and facilitating the installation and damage resistance of the steel pipe pile and the cement soil compaction pile.

Description

Technical Field

[0001] This invention relates to the field of tunnel foundation reinforcement technology, specifically to a composite multifunctional pile foundation for loess tunnel foundation reinforcement and its construction method. Background Technology

[0002] Cement-soil compaction piles are mainly used in loess tunnel construction to eliminate the collapsibility of the foundation loess and improve the bearing capacity of the foundation. However, since the surrounding rock of the foundation of loess tunnels is usually relatively weak, after construction and excavation, the tunnel body deforms and becomes unstable due to unloading and redistribution of ground stress, and the invert arch heaves and cracks. The cement-soil compaction piles generate large tensile stress due to the upward deformation of the foundation surrounding rock, which leads to the fracture of the pile body and loss of its function of eliminating collapsibility and reinforcing the surrounding rock. This results in the deformation and instability of the tunnel structure during the construction stage and the later bulging of the tunnel invert arch due to groundwater intrusion, which leads to mud pumping and mud leakage, seriously affecting traffic safety and operation.

[0003] 1. In existing technologies, loess, as a special soil type, presents numerous challenges during tunnel construction. Loess is characterized by its high porosity, susceptibility to water erosion, and significant collapsibility, making foundation reinforcement work particularly complex and crucial when constructing tunnels in loess areas. Currently, the most commonly used foundation reinforcement methods are cement-soil compaction piles and jet grouting piles. However, due to the weak surrounding rock of loess tunnel foundations, the bottom surrounding rock undergoes significant heave and deformation after excavation, resulting in substantial tensile stress on the pile foundations. Furthermore, cement-soil compaction piles and jet grouting piles utilize cement mortar-like materials with low tensile strength, making the pile foundations highly prone to fracture. This leads to the pile foundations losing their designed function in the early stages of construction, resulting in cracking and damage to the tunnel body and invert arch structures during later construction and operation, thus compromising the structural safety and reliability.

[0004] 2. In the existing technology, steel pipe piles have low strength and are not easy to insert into the foundation. Connecting adjacent steel pipe piles is time-consuming and laborious. At the same time, cement-soil compaction piles are not tightly bonded to the foundation and are prone to deformation and damage. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a composite multifunctional pile foundation for reinforcing loess tunnel foundations and a construction method thereof, in order to solve the problems mentioned in the background section.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a composite multifunctional pile foundation for reinforcing the foundation of loess tunnels, comprising a foundation, a tunnel body being provided on the upper side of the foundation, steel pipe piles being uniformly arranged in the corresponding subgrade of the lower surface of the tunnel body, and cement-soil compaction piles being arranged in the foundation between the steel pipe piles.

[0007] The steel pipe pile includes a steel pipe body, reinforcing rings, rectangular notches, a first limiting block, a conical head, a second limiting block, a conical sleeve, a through hole, and fasteners. Two reinforcing rings are fixedly installed on the lower edge of the inner wall of the steel pipe body, and rectangular notches are opened on the left and right sides of the reinforcing rings near the outer side. A conical head is installed on the lower surface of the steel pipe body corresponding to the rectangular notch through the first limiting block. A second limiting block is fixedly installed on the upper side of the inner wall of the steel pipe body. Conical sleeves are evenly fitted from top to bottom on the outer surface of the steel pipe body. Through holes are symmetrically opened on the conical sleeves and the side wall of the steel pipe body, and fastening components are installed in the threads of the through holes.

[0008] The cement-soil compaction pile includes a semi-circular plate, a conical barb, and a filler. Two semi-circular plates are arranged on the left and right sides, and the conical barbs are evenly arranged on the inner and outer walls of the semi-circular plates. The semi-circular plates are filled with a filler.

[0009] As a preferred embodiment of the present invention, the steel pipe body has a diameter of 108mm, a wall thickness of 6mm, a pile length of 6m-10m, and is arranged in a quincunx pattern with a spacing of 1m-1.2m.

[0010] As a preferred embodiment of the present invention, one steel pipe pile is arranged on each side of the junction of the inverted arch and the corner of the tunnel main body side wall, with an angle of 10-20° with the vertical. Six to ten steel pipe piles are arranged vertically at the inverted arch according to the span of the tunnel main body.

[0011] As a preferred technical solution of the present invention, the main body of the steel pipe is made of steel of not less than HRB400, and holes are drilled within 1m-1.5m at the bottom end of the main body of the steel pipe, with a hole diameter of 2m-5mm, a longitudinal hole spacing of 10m-15cm, and 2-3 holes evenly distributed in the circumferential direction.

[0012] As a preferred embodiment of the present invention, the through holes and fasteners corresponding to the upper and lower parts of the steel pipe body and the conical sleeve are arranged in a cross shape.

[0013] As a preferred embodiment of the present invention, the cement-soil compaction piles have a diameter of 0.4m-0.6m, a pile length of 10m-15m, and are arranged in a staggered pattern with a spacing of 1m-1.2m.

[0014] As a preferred embodiment of the present invention, the semi-circular plate is made of stainless steel mesh plate, and the thickness of the semi-circular plate is 3mm-5mm.

[0015] As a preferred embodiment of the present invention, the filler is made of early-strength silicate cement with a strength grade not lower than P.O42.5R, and the soil is made of silty clay with a maximum particle size of less than 0.076mm.

[0016] A construction method for composite multifunctional pile foundation reinforcement of loess tunnel foundation includes the following steps:

[0017] S1. Placement of steel pipe piles: Move the diesel hammer pile driver into the tunnel body and place the steel pipe piles at the junction of the invert arch and the side wall corner of the tunnel body. Place one pile on each side and make an angle of 10-20° with the vertical. Place 6-10 piles vertically at the invert arch according to the tunnel body span.

[0018] S2. Steel pipe pile installation: The steel pipe pile is lifted and inserted into the foundation. The steel pipe pile is driven down by a diesel hammer pile driver. The second limiting block on the upper side of the lower steel pipe body is inserted between the reinforcing rings in the adjacent upper steel pipe body through the rectangular notch. The steel pipe pile is driven down to the design depth.

[0019] S3. Grouting of steel pipe piles: Cut the steel pipe piles and perform pressure grouting. One day after the steel pipe piles are completed, construct the cement-soil compaction piles at the base.

[0020] S4. Cement-soil compaction pile drilling: Drilling holes between steel pipe piles using a diesel hammer pile driver to the designed depth;

[0021] S5. Soil compaction pile installation: Place the symmetrical semi-circular plates into the drilling hole, then pressurize the filling material between the left and right semi-circular plates, and squeeze the semi-circular plates to both sides against the inner wall of the drilling hole.

[0022] Beneficial effects

[0023] Compared with the prior art, the present invention provides a composite multifunctional pile foundation for reinforcing the foundation of loess tunnels and a construction method thereof, which has the following beneficial effects:

[0024] 1. The composite multi-functional pile foundation and construction method for reinforcing the loess tunnel foundation, by installing steel pipe piles followed by cement-soil compaction piles, not only ensures the foundation reinforcement and protection of the tunnel structure's safe bearing capacity, but also ensures that the cement-soil compaction piles do not break during the construction and operation phases, thereby preventing subsidence and settlement, and thus ensuring the safety and reliability of the tunnel structure throughout its entire lifespan.

[0025] 2. The composite multi-functional pile foundation and construction method for reinforcing the loess tunnel foundation greatly improves the strength of the steel pipe piles by setting conical heads, conical sleeves and fasteners in the steel pipe piles, and facilitates the connection of steel pipe piles. This makes the cement-soil compaction piles strong, able to form a tight structure with the foundation, easy to install and not easily damaged. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a composite multifunctional pile foundation structure for reinforcing the foundation of loess tunnels proposed in this invention;

[0027] Figure 2This is a schematic diagram of a steel pipe pile structure for a composite multifunctional pile foundation for reinforcing loess tunnel foundations proposed in this invention.

[0028] Figure 3 This is a cross-sectional view of a steel pipe pile for a composite multifunctional pile foundation for reinforcing loess tunnel foundations proposed in this invention.

[0029] Figure 4 This is a cross-sectional view of a cement-soil compaction pile for a composite multifunctional pile foundation for reinforcing loess tunnel foundations proposed in this invention.

[0030] Figure 5 This is a schematic diagram of the process for a composite multifunctional pile foundation and construction method for reinforcing the foundation of loess tunnels proposed in this invention.

[0031] In the diagram: 1. Foundation; 2. Tunnel main body; 3. Steel pipe pile; 301. Steel pipe main body; 302. Reinforcing ring; 303. Rectangular notch; 304. First limiting block; 305. Conical head; 306. Second limiting block; 307. Conical sleeve; 308. Through hole; 309. Fastener; 4. Cement-soil compaction pile; 401. Semi-circular plate; 402. Conical barb; 403. Filler. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Please refer to Figures 1-5 This invention discloses a composite multifunctional pile foundation for reinforcing the foundation of loess tunnels, including a foundation 1, a tunnel body 2 is provided on the upper side of the foundation 1, steel pipe piles 3 are uniformly provided in the foundation 1 corresponding to the lower surface of the tunnel body 2, and cement-soil compaction piles 4 are provided in the foundation 1 between the steel pipe piles 3.

[0034] The steel pipe pile 3 includes a steel pipe body 301, reinforcing rings 302, rectangular notches 303, a first limiting block 304, a conical head 305, a second limiting block 306, a conical sleeve 307, a through hole 308, and fasteners 309. Two reinforcing rings 302 are fixedly installed on the lower edge of the inner wall of the steel pipe body 301, and rectangular notches 303 are opened on the left and right sides of the reinforcing rings 302 near the outer side. A conical head 305 is installed on the lower surface of the steel pipe body 301 corresponding to the rectangular notch 303 through the first limiting block 304. A second limiting block 306 is fixedly installed on the upper side of the inner wall of the steel pipe body 301. Conical sleeves 307 are evenly fitted from top to bottom on the outer surface of the steel pipe body 301. Through holes 308 are symmetrically opened on the side wall of the conical sleeves 307 and the steel pipe body 301, and fastening components are installed in the internal threads of the through holes 308.

[0035] The cement-soil compaction pile 4 includes a semi-circular plate 401, a conical barb 402, and a filler 403. Two semi-circular plates 401 are arranged on the left and right sides, and the conical barbs 402 are evenly arranged on the inner and outer walls of the semi-circular plates 401. The filler 403 is filled between the semi-circular plates 401.

[0036] Specifically, the steel pipe body 301 has a diameter of 108mm, a wall thickness of 6mm, and a pile length of 6m-10m, and is arranged in a quincunx pattern with a spacing of 1m-1.2m.

[0037] In this embodiment, the steel pipe body 301 has good strength and is evenly distributed, resulting in a good reinforcement effect.

[0038] Specifically, one steel pipe pile 3 is arranged on each side of the junction of the inverted arch and the wall corner of the tunnel body 2, with an angle of 10-20° with the vertical. Six to ten steel pipe piles are arranged vertically at the inverted arch according to the span of the tunnel body 2.

[0039] In this implementation plan, the steel pipe piles 3 are evenly distributed to improve the strength of the invert arch of the tunnel body 2.

[0040] Specifically, the steel pipe body 301 is made of steel of not less than HRB400. Holes are drilled in the bottom end of the steel pipe body 301 within a range of 1m-1.5m, with a hole diameter of 2m-5mm, a longitudinal hole spacing of 10m-15cm, and 2-3 holes evenly distributed in the circumferential direction.

[0041] In this implementation plan, the steel pipe body 301 has high strength and is easy to drill holes for subsequent pressure grouting.

[0042] Specifically, the through holes 308 and fasteners 309 on the steel pipe body 301 and the conical sleeve 307 are arranged in a cross shape.

[0043] In this embodiment, the tapered sleeve 307 and the fastener 309 make the steel pipe body 301 stronger, and the tapered sleeve 307 facilitates the insertion of the steel pipe body 301 into the foundation 1.

[0044] Specifically, the cement-soil compaction piles 4 have a diameter of 0.4m-0.6m, a pile length of 10m-15m, are arranged in a quincunx pattern, and are spaced 1m-1.2m apart.

[0045] In this implementation plan, the cement-soil compaction piles 4 are evenly distributed, resulting in a better reinforcement effect on the foundation 1.

[0046] Specifically, the semi-circular plate 401 is made of stainless steel mesh, and the thickness of the semi-circular plate 401 is 3mm-5mm.

[0047] In this embodiment, the semi-circular plate 401 facilitates the outflow of the filler 403, resulting in a better bonding effect.

[0048] Specifically, the filler 403 uses early-strength silicate cement with a strength grade not lower than P.O42.5R, and the soil uses silty clay with a maximum particle size of less than 0.076mm.

[0049] In this embodiment, the filler 403 has high strength, the ratio of cement to soil in the filler 403 is 0.3:1, and the water content of the cement-soil mixture is 20-30%.

[0050] A construction method for composite multifunctional pile foundation reinforcement of loess tunnel foundation includes the following steps:

[0051] S1. Placement of steel pipe piles: Move the diesel hammer pile driver into the tunnel body 2. Arrange the steel pipe piles 3 at the junction of the inverted arch and the side wall corner of the tunnel body 2. Arrange one pile on each side, with an angle of 10-20° with the vertical. Arrange 6-10 piles vertically at the inverted arch according to the span of the tunnel body 2.

[0052] S2. Steel pipe pile installation: Lift the steel pipe pile 3 and insert it into the foundation 1. Use a diesel hammer pile driver to sink the steel pipe pile 3 so that the second limiting block 306 on the upper side of the lower steel pipe body 301 is inserted between the reinforcing rings 302 in the adjacent upper steel pipe body 301 through the rectangular notch 303. Sink the steel pipe pile 3 to the design depth.

[0053] S3, Steel pipe pile grouting: Cut the steel pipe pile 3 and perform pressure grouting. One day after the steel pipe pile 3 is completed, construct the foundation cement-soil compaction pile 4.

[0054] S4. Cement-soil compaction pile drilling: Drill holes between steel pipe piles 3 using a diesel hammer pile driver until the designed depth is reached;

[0055] S5. Soil compaction pile installation: Place the symmetrical semi-circular plates 401 into the drilling hole, then pressurize the filler 403 between the left and right semi-circular plates 401, and squeeze the semi-circular plates 401 to both sides against the inner wall of the drilling hole.

[0056] The working principle and usage process of this invention are as follows: After the construction of the side walls of the tunnel main body 2 is completed and the excavation of the invert arch soil is finished, steel pipe piles are installed. The diesel hammer pile driver is moved into the tunnel main body 2. Steel pipe piles 3 are arranged at the junction of the side walls and the invert arch of the tunnel main body 2, one on each side, with an angle of 10-20° to the vertical. Six to ten piles are vertically arranged at the invert arch according to the span of the tunnel main body 2. The steel pipe piles 3 are lifted and inserted into the foundation 1. The diesel hammer pile driver is used to sink the steel pipe piles 3, causing the lower steel pipe main body 301 to... The upper second limiting block 306 is inserted between the reinforcing rings 302 inside the adjacent upper steel pipe body 301 through the rectangular notch 303, driving the steel pipe pile 3 to the design depth. The steel pipe pile 3 is then cut and pressure grouting is performed. One day after the steel pipe pile 3 is completed, the foundation cement-soil compaction pile 4 is constructed. A diesel hammer pile driver is used to drill holes between the steel pipe piles 3 to the design depth. Symmetrical semi-circular plates 401 are then placed into the holes, and the filling material 403 is injected under pressure between the left and right semi-circular plates 401. Plate 401 presses against the inner wall of the borehole on both sides. By installing steel pipe piles 3 and then cement-soil compaction piles 4, not only is the safe bearing capacity of the foundation 1 reinforced and protected, but the cement-soil compaction piles 4 are also guaranteed not to break during construction and operation, thus preventing subsidence and ensuring the safety and reliability of the tunnel main structure 2 throughout its entire lifespan. The first limiting block 304 in the steel pipe pile 3 is inserted between the upper and lower reinforcing rings 302 through the rectangular notch 303. The first limiting block 304 is then rotated to install the conical head 305. The lower surface of the steel pipe body 301 facilitates the insertion of the steel pipe pile 3 into the foundation 1. The upper second limiting block 306 facilitates docking with the upper steel pipe pile 3. Furthermore, the strength of the steel pipe pile 3 is greatly improved by the reinforcing ring 302, the conical sleeve 307, and the fasteners 309, making it less prone to damage. The filling body 403 is inserted between the left and right semi-circular plates 401. The conical barbs 402 between the inner and outer walls of the semi-circular plates 401 are inserted into the foundation 1 and the filling body 403, making the cement-soil compaction pile 4 strong, able to form a tight structure with the foundation 1, which is conducive to installation and less prone to damage.

[0057] In summary, the composite multi-functional pile foundation and construction method for reinforcing the loess tunnel foundation, by constructing steel pipe piles 3 followed by cement-soil compaction piles 4, not only ensures the safe bearing capacity of the reinforced foundation 1 and the tunnel structure, but also ensures that the cement-soil compaction piles 4 do not break during the construction and operation phases, thus preventing subsidence and settlement. This ensures the safety and reliability of the tunnel main structure 2 throughout its entire lifespan. Furthermore, the steel pipe piles 3 and the cement-soil compaction piles 4 have high strength, are easy to install, and are not easily damaged.

[0058] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite multifunctional pile foundation for reinforcing the foundation of loess tunnels, comprising a foundation (1), characterized in that: The upper side of the foundation (1) is provided with a tunnel body (2), and steel pipe piles (3) are uniformly arranged in the corresponding bottom foundation (1) on the lower surface of the tunnel body (2). Cement-soil compaction piles (4) are arranged in the foundation (1) between the steel pipe piles (3). The steel pipe pile (3) includes a steel pipe body (301), reinforcing rings (302), rectangular notches (303), a first limiting block (304), a conical head (305), a second limiting block (306), a conical sleeve (307), a through hole (308), and fasteners (309). Two reinforcing rings (302) are fixedly installed on the lower edge of the inner wall of the steel pipe body (301), and rectangular notches (303) are opened on the left and right sides of the reinforcing rings (302) near the outer side. (303) A conical head (305) is installed on the lower surface of the corresponding steel pipe body (301) through the first limiting block (304). A second limiting block (306) is fixedly installed on the upper side of the inner wall of the steel pipe body (301). Conical sleeves (307) are uniformly fitted from top to bottom on the outer surface of the steel pipe body (301). Through holes (308) are symmetrically opened on the side wall of the conical sleeve (307) and the steel pipe body (301), and fastening components are installed in the internal threads of the through holes (308). The cement-soil compaction pile (4) includes a semi-circular plate (401), a conical barb (402), and a filler (403). There are two semi-circular plates (401) on the left and right sides, and the conical barbs (402) are evenly arranged on the inner and outer walls of the semi-circular plates (401). The filler (403) is filled between the semi-circular plates (401). The main body of the steel pipe (301) has a diameter of 108mm, a wall thickness of 6mm, and a pile length of 6m-10m. It is arranged in a quincunx pattern with a spacing of 1m-1.2m. The steel pipe piles (3) are arranged one on each side at the junction of the inverted arch and the side wall corner of the tunnel body (2), with an angle of 10-20° with the vertical. Six to ten piles are arranged vertically at the inverted arch according to the span of the tunnel body (2). The cement-soil compaction piles (4) have a diameter of 0.4m-0.6m, a pile length of 10m-15m, and are arranged in a quincunx pattern with a spacing of 1m-1.2m.

2. The composite multifunctional pile foundation for reinforcing loess tunnel foundation according to claim 1, characterized in that: The main body of the steel pipe (301) is made of steel of not less than HRB400. Holes are drilled in the bottom 1m-1.5m range of the main body of the steel pipe (301), with a hole diameter of 2m-5mm, a longitudinal hole spacing of 10m-15cm, and 2-3 holes evenly distributed in the circumferential direction.

3. The composite multifunctional pile foundation for reinforcing loess tunnel foundation according to claim 1, characterized in that: The steel pipe body (301) and the corresponding through holes (308) and fasteners (309) on the tapered sleeve (307) are arranged in a cross shape.

4. The composite multifunctional pile foundation for reinforcing loess tunnel foundation according to claim 1, characterized in that: The semi-circular plate (401) is made of stainless steel mesh, and the thickness of the semi-circular plate (401) is 3mm-5mm.

5. The composite multifunctional pile foundation for reinforcing loess tunnel foundation according to claim 1, characterized in that: The filler (403) is made of early-strength silicate cement with a strength grade not lower than P.O42.5R, and the soil is silty clay with a maximum particle size of less than 0.076mm.

6. A construction method for a composite multifunctional pile foundation for reinforcing the foundation of loess tunnels, the method being based on the composite multifunctional pile foundation for reinforcing the foundation of loess tunnels described in claim 1, characterized in that... Includes the following steps: S1. Placement of steel pipe piles: Move the diesel hammer pile driver into the tunnel body (2), and arrange the steel pipe piles (3) at the junction of the side wall corner and the inverted arch of the tunnel body (2), with one pile on each side and an angle of 10-20° with the vertical. Arrange 6-10 piles vertically at the inverted arch according to the span of the tunnel body (2). S2, Steel pipe pile installation: Lift the steel pipe pile (3) and insert it into the foundation (1). Use a diesel hammer pile driver to sink the steel pipe pile (3) so that the second limiting block (306) on the upper side of the lower steel pipe body (301) is inserted between the reinforcing rings (302) in the adjacent upper steel pipe body (301) through the rectangular notch (303). Sink the steel pipe pile (3) to the design depth. S3, Steel pipe pile grouting: Cut the steel pipe pile (3) and perform pressure grouting. One day after the steel pipe pile (3) is completed, the foundation cement soil compaction pile (4) is constructed. S4. Cement-soil compaction pile drilling: Drilling is carried out between steel pipe piles (3) using a diesel hammer pile driver until the designed depth is reached; S5. Soil compaction pile installation: Place the symmetrical semi-circular plates (401) into the hole, and then pressurize the filler (403) between the left and right semi-circular plates (401) to squeeze the inner wall of the hole to both sides.

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