A construction method of a foundation pit support pile arranged close to a tunnel edge

Abstract

This invention relates to a construction method for retaining piles for a foundation pit, positioned adjacent to the edge of a tunnel and located between the foundation pit and the tunnel. The method includes the following steps: Firstly, a plurality of first-row MJS jet grouting holes are driven at intervals on one side of the tunnel, the depth of which is the same as the driving depth of the I-beams; Grouting is injected into the first-row MJS jet grouting holes to form a semi-circular first-row MJS isolation pile, the arc-shaped section of which faces the foundation pit, with adjacent first-row MJS isolation piles partially overlapping; Several I-beams are driven at intervals in the soil outside the foundation pit, located between the foundation pit and the tunnel; Second-row MJS jet grouting holes are driven between adjacent I-beams, the depth of which is the same as the depth of the I-beams; Grouting is injected into the second-row MJS jet grouting holes to form a semi-circular second-row MJS pile, with the first-row MJS isolation piles and the second-row MJS piles partially overlapping.

Description

Technical Field

[0001] This invention relates to the field of construction engineering, and specifically to a construction method for retaining piles for foundation pits installed close to the edge of a tunnel. Background Technology

[0002] With the rapid development of China's infrastructure technology, the development and utilization of underground resources is also increasing. The development and utilization of underground space resources has become an inevitable trend in the current infrastructure development context. Among these, the subway system, due to its many advantages, has become a major and inseparable component of the urban passenger transport system, greatly facilitating people's lives and travel. As more and more subway lines are opened and the subway network becomes increasingly dense, the development of urban underground space is becoming more and more common, and buildings along subway lines are springing up, but this has also brought about many problems. Among these, the issue of foundation pit construction near existing subway lines is becoming increasingly prominent, resulting in a large number of deep foundation pit projects adjacent to subway tunnels. During the excavation of deep foundation pits, the unloading of excavated soil causes changes in the stress and displacement fields of the surrounding soil, directly affecting the structural safety and normal operation of the subway tunnels.

[0003] To ensure the stability and safety of the tunnel during subsequent construction, a series of measures need to be taken to reinforce the tunnel structure. The conventional approach is to reinforce the tunnel structure by adding steel supports or installing concrete beams and columns to enhance its stability and seismic resistance. However, such measures consume a great deal of manpower and resources. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a construction method for retaining piles for a foundation pit set close to the edge of a tunnel. The first row of MJS isolation piles is a jet-grouted first row of MJS isolation piles between the foundation pit and the tunnel. The I-beams and the second row of MJS construction piles provide support for the edge of the foundation pit. The first row of MJS isolation piles and the second row of MJS construction piles strengthen the soil between the foundation pit and the tunnel, reducing the impact on the tunnel during foundation pit construction. The first row of MJS isolation piles and the second row of MJS construction piles partially overlap to increase the waterproofness between the foundation pit and the tunnel.

[0005] The technical solution to achieve the above objectives is a construction method for retaining piles for foundation pits, which are installed close to the edge of the tunnel and placed between the foundation pit and the tunnel. The method includes the following steps:

[0006] Several first-row MJS swivel nozzles are drilled on the side of the foundation pit near the tunnel and at the position corresponding to the I-beam. The depth of the first-row MJS swivel nozzles is the same as the drilling depth of the I-beam.

[0007] Grouting is performed at the first row of MJS swing jet holes to form a semi-circular first row of MJS isolation piles. The arc-shaped section of the first row of MJS isolation piles faces the foundation pit, and two adjacent first row of MJS isolation piles partially overlap.

[0008] Several I-beams are installed at intervals in the soil outside the foundation pit and between the foundation pit and the tunnel;

[0009] A second row of MJS oscillating spray holes is drilled between two adjacent I-beams, and the depth of the second row of MJS oscillating spray holes is the same as the depth of the I-beams;

[0010] Grouting is performed at the second row of MJS swing jet holes to form a semi-circular second row of MJS method piles. The arc-shaped section of the second row of MJS method piles faces the tunnel. There is partial overlap between adjacent second rows of MJS method piles, and there is partial overlap between the first row of MJS isolation piles and the second row of MJS method piles.

[0011] Furthermore, before driving the I-beams, several MJS method piles are driven into the soil outside the foundation pit and along the remaining three sides of the foundation pit, with some overlap between adjacent MJS method piles.

[0012] Furthermore, the piles are installed using the MJS method.

[0013] Furthermore, the depth of the piles constructed using this method is adapted to the depth of the foundation pit.

[0014] Furthermore, before inserting the I-beams, MJS isolation piles are driven on the outside of the tunnel.

[0015] Furthermore, the distance between the first row of MJS isolation piles and the second row of MJS construction method piles is less than the sum of the radii of the first row of MJS isolation piles and the second row of MJS construction method piles, and the two rows of piles must overlap.

[0016] Furthermore, the radii of the first row of MJS isolation piles and the second row of MJS method piles are equal.

[0017] Furthermore, before drilling the second row of MJS swing spray holes, reinforced I-beams are drilled on both sides of the foundation pit.

[0018] Furthermore, the I-beam is installed in the soil by high-frequency non-resonance hammering.

[0019] Furthermore, the first row of MJS isolation piles and the second row of MJS method piles are installed using the MJS method.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] The I-beams are driven into the foundation pit using a high-frequency non-resonance hammer, allowing them to be installed at the edge of the pit with minimal disturbance to the surrounding soil. The I-beams provide support for the edge of the foundation pit. By jet grouting the first row of MJS isolation piles and the second row of MJS construction piles between the foundation pit and the tunnel, the strength of the soil between the foundation pit and the tunnel is enhanced, reducing the impact on the tunnel during foundation pit construction. Attached Figure Description

[0022] Figure 1 This is a plan view of the foundation pit retaining piles installed adjacent to the edge of the tunnel, according to the present invention.

[0023] Figure 2 This is a diagram illustrating the effect of using a positioning component in a construction method for foundation pit retaining piles installed close to the edge of a tunnel, as described in this invention.

[0024] Legend: 1. Excavation pit; 11. I-beam; 12. Second row of MJS method piles; 13. Positioning component; 2. Tunnel; 21. First row of MJS isolation piles. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0026] See Figure 1 A construction method for retaining piles for a foundation pit, located between the foundation pit 1 and the tunnel 2, includes the following steps: driving a plurality of first-row MJS jet grouting holes at intervals on the outside of the tunnel 2, the depth of the first-row MJS jet grouting holes being consistent with the driving depth of the I-beams 11; grouting the first-row MJS jet grouting holes to form a semi-circular first-row MJS isolation pile 21, the arc-shaped section of the first-row MJS isolation pile 21 facing the foundation pit 1, with adjacent first-row MJS isolation piles 21 partially overlapping; and then grouting the foundation pit... A number of I-beams 11 are driven into the soil outside the foundation pit 1 and between the tunnel 2 at intervals; a second row of MJS swivel jet holes is driven between two adjacent I-beams 11, the depth of the second row of MJS swivel jet holes is the same as the depth of the I-beams 11; grouting is carried out in the second row of MJS swivel jet holes to form a semi-circular second row of MJS method piles 12, the arc section of the second row of MJS method piles 12 faces the tunnel 2, and the first row of MJS isolation piles 21 and the second row of MJS method piles 12 partially overlap.

[0027] In this invention, a preferred embodiment is as follows: Several first-row MJS swivel jet holes are drilled into the soil outside tunnel 2 using a drilling rig, and grout is injected into these holes. The grouting material is generally cement grout or polymer grout. To prevent potential safety risks to the tunnel lining segments due to the grouting pressure, the cement grout is not injected under pressure towards tunnel 2, resulting in a swivel jet angle of 180 degrees to form a semi-circular structure. During grouting, the grouting equipment is gradually raised to avoid uneven distribution of the grout within the soil. After grouting, several first-row MJS isolation piles 21 are formed, with partial overlap between adjacent piles to form isolation sections. Several I-beams 11 are installed in the edge soil between the foundation pit 1 and tunnel 2. These I-beams 11 are vertically driven into the soil to provide vertical support and prevent soil collapse or subsidence. The soil between the two I-beams 11 is drilled with a second row of MJS jet grouting holes, and grout is injected into the second row of MJS jet grouting holes. In order to prevent the pile diameter from affecting the excavation of the foundation pit 1 during grouting, the cement grout is not pressurized in the direction of the foundation pit 1, so that the jet grouting angle is 180 degrees to form a semi-circular structure. After the grouting is completed, the several second row of MJS piles 12 formed by grouting have partial overlap between adjacent second row of MJS piles 12 to form a water-stop section, which can effectively prevent the infiltration and leakage of groundwater. The second row of MJS piles 12 and the first row of MJS isolation piles 21 also partially overlap to increase the continuity of the support and reduce the gap between the supports, which can effectively prevent the soil from settling and sliding, making the entire support structure more stable and reliable. In order to ensure the stability of the foundation pit 1 during excavation, several MJS piles are also set on several other sides outside the foundation pit 1.

[0028] Furthermore, before driving the I-beams, several MJS method piles are driven into the soil outside the foundation pit and along the remaining three sides of the foundation pit, with partial overlap between adjacent piles. These piles reinforce the soil at the edge of the foundation pit, preventing collapse during subsequent construction.

[0029] Furthermore, the piles are installed using the MJS method.

[0030] Furthermore, the depth of the piles constructed using this method is adapted to the depth of the foundation pit.

[0031] Furthermore, before inserting the I-beams, MJS isolation piles are driven on the outside of the tunnel.

[0032] Furthermore, the distance between the first row of MJS isolation piles and the second row of MJS method piles is less than the sum of the radii of the first method piles and the second method piles.

[0033] Furthermore, the radii of the first row of MJS isolation piles and the second row of MJS method piles are equal.

[0034] Furthermore, before the second row of MJS piles in the sprayed concrete, reinforced I-beams are driven into the two adjacent sides outside the foundation pit.

[0035] Furthermore, during the installation of the I-beam 11, a positioning element 13 is provided. The positioning element 13 is installed on top of the soil to position the I-beam 11. The positioning element 13 includes a side plate and two clamping plates installed on the side plate. The distance between the two clamping plates is adapted to the distance between the two opposing structural plates of the I-beam. The positioning element 13 is fixed at the installation position of the I-beam 11. During installation, the positioning element 13 is fixed above a guide wall. Preferably, the two clamping plates are located between the inner walls of the guide wall. Then, the I-beam 11 is installed in the soil to ensure accurate positioning.

[0036] Furthermore, the I-beam 11 is driven into the soil using a high-frequency non-resonant hammer. The high-frequency non-resonant hammer has a high impact frequency, enabling the I-beam 11 to be driven into the soil quickly, and the vibration amplitude generated during impact is small, reducing the impact on surrounding structures. This avoids damage to the foundation pit 1 and tunnel 2 structures due to excessive impact during construction. Preferably, an ICE high-frequency non-resonant hammer is used to drive the I-beam 11.

[0037] Furthermore, the first row of MJS isolation piles 21 and the second row of MJS method piles 12 are installed using the MJS method. The MJS method reduces the construction time of the retaining structure and minimizes interference and impact on the surrounding environment. It also offers fast construction speed and minimizes vibration and noise.

[0038] The following describes the construction process of a method for constructing retaining piles for foundation pits located adjacent to the edge of a tunnel, according to the present invention.

[0039] Several first-row MJS swivel jet holes are drilled into the soil on one side of tunnel 2 using a drilling rig, and grout is injected into these holes. The grouting material typically used is cement grout or polymer grout. To prevent potential safety risks to the tunnel lining segments due to the grouting pressure, the cement grout is not injected with pressure towards tunnel 2, resulting in a 180-degree swivel jet angle to form a semi-circular structure. During grouting, the grouting equipment is gradually raised to avoid uneven distribution of the grout within the soil. After grouting, several first-row MJS isolation piles 21 are formed, with partial overlap between them to create a waterproof section. Several I-beams 11 are installed between the edge soil of the pit 1 and tunnel 2, vertically driven into the soil to provide vertical support. To prevent soil collapse or subsidence, a second row of MJS swivel jet holes is drilled between the two I-beams 11, and grout is injected into these holes. To prevent the pile diameter from affecting the excavation of the foundation pit 1 during grouting, the cement grout is not injected under pressure towards the foundation pit 1, resulting in a swivel jet angle of 180 degrees to form a semi-circular structure. After grouting, several second-row MJS method piles 12 formed by grouting overlap to form a water-stop section, effectively preventing groundwater infiltration and leakage. Furthermore, there is partial overlap between the second-row MJS method piles 12 and the first-row MJS isolation piles 21, increasing the continuity of the support and reducing the gaps between supports. This effectively prevents soil subsidence and sliding, making the entire support structure more stable and reliable.

[0040] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. Those skilled in the art can make various modifications to the present invention based on the above description. Therefore, certain details in the embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention shall be defined by the appended claims.

Claims

1. A construction method for retaining piles for a foundation pit, which are installed adjacent to the edge of a tunnel, wherein the retaining piles are installed between the foundation pit and the tunnel, characterized in that... Includes the following steps: A first row of MJS swivel nozzles is drilled on the side of the foundation pit near the tunnel, and the depth of the first row of MJS swivel nozzles is the same as the drilling depth of the I-beams. Grouting is performed at the first row of MJS swing jet holes to form a semi-circular first row of MJS isolation piles. The arc-shaped section of the first row of MJS isolation piles faces the foundation pit, and two adjacent first row of MJS isolation piles partially overlap. Several I-beams are installed at intervals in the soil outside the foundation pit and between the foundation pit and the tunnel; A second row of MJS oscillating spray holes is drilled between two adjacent I-beams, and the depth of the second row of MJS oscillating spray holes is the same as the depth of the I-beams; Grouting is performed at the second row of MJS swing jet holes to form a semi-circular second row of MJS method piles. The arc-shaped section of the second row of MJS method piles faces the tunnel. There is partial overlap between adjacent second rows of MJS method piles, and there is partial overlap between the first row of MJS isolation piles and the second row of MJS method piles. The distance between the first row of MJS isolation piles and the second row of MJS construction method piles is less than the sum of the radii of the first row of MJS isolation piles and the second row of MJS construction method piles, and the two rows of piles must overlap; Before inserting the I-beams, MJS isolation piles were driven on the outside of the tunnel; Before drilling the second row of MJS swing spray holes, reinforced I-beams were continued to be drilled on both sides of the foundation pit; When installing the I-beam, a positioning element is provided and placed on top of the soil. The positioning element is used to position the I-beam. The positioning element includes a side plate and two clamping plates installed on the side plate. The distance between the two clamping plates is adapted to the distance between the two structural plates of the I-beam that are arranged opposite to each other. The positioning element is fixed at the installation position of the I-beam. When installing the I-beam, the positioning element is fixed above the guide wall.

2. The construction method of the foundation pit retaining piles set adjacent to the tunnel edge according to claim 1, characterized in that: Before driving the I-beams, several MJS method piles are driven into the soil outside the foundation pit and along the other three sides of the foundation pit, with some overlap between two adjacent MJS method piles. The piles were driven using the MJS method. The depth of the piles constructed using the method is adapted to the depth of the foundation pit.

3. The construction method of the foundation pit retaining piles set adjacent to the tunnel edge according to claim 1, characterized in that: The first row of MJS isolation piles and the second row of MJS method piles have the same radius.

4. The construction method of the foundation pit retaining piles set adjacent to the tunnel edge according to claim 1, characterized in that: The I-beams are installed in the soil by high-frequency, non-resonant hammering.

5. The construction method of the foundation pit retaining piles set adjacent to the tunnel edge according to claim 1, characterized in that: The first row of MJS isolation piles and the second row of MJS method piles were installed using the MJS method.

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