Shield tunneling method in water-rich sand layer by mjs pre-reinforcement

Abstract

This invention provides a method for pre-reinforcement construction of a shield tunnel in a water-rich sand layer using the MJS method, comprising the following steps: (1) constructing a guide pier according to the hole location, laying out the hole location and installing a flange on the guide pier, and installing a check valve on the flange; (2) installing a pilot hole machine in the foundation pit, closing the check valve, and drilling the pilot hole machine through the retaining piles using a core drill; (3) removing the core drill, installing an outer casing on the pilot hole machine, using the outer casing for pilot hole advance, and installing an inner drill rod inside the outer casing on the pilot hole machine, continuing to pilot the hole to the design depth using the inner drill rod, and injecting double grout into the hole during the pilot hole process; (4) pulling out the inner drill rod, removing the pilot hole machine, installing an MJS grouting machine in the foundation pit, installing a grouting pipe on the MJS grouting machine, and installing the grouting pipe to the design depth; (5) pulling out the outer casing; (6) retracting the grouting pipe using the MJS grouting machine, and spraying grout into the grouting pipe, while simultaneously dismantling the grouting pipe that has been withdrawn from the hole.

Description

Technical Field

[0001] This invention relates to the field of building engineering technology, and in particular to a method for pre-reinforcement construction of MJS tunnels in water-rich sand layers. Background Technology

[0002] Currently, for tunnel projects where the superstructure is densely covered with underground structures, the stratum within the shield tunnel is water-rich sand, and multiple vertical piles and high-strength pipe piles are intruded, the shield tunnel must undergo pretreatment, which is quite difficult. The traditional pretreatment methods for tunnels with water-rich sand layers overlying underground structures are mainly the conventional MJS method or the freezing method. However, if multiple vertical piles and high-strength pipe piles are intruded within the tunnel area, the conventional MJS method cannot penetrate the vertical piles and high-strength pipe piles, and sand and water are prone to surge in the water-rich sand layer, which can easily lead to safety accidents. The freezing method is relatively expensive and has poor deformation control for underground structures, so its applicability is relatively poor for underground structures with strict deformation control.

[0003] Therefore, it is necessary to provide a method for pre-reinforcing shield tunnels in water-rich sand layers that enables drilling through areas containing high-strength pipe piles and reduces water and sand inflow. Summary of the Invention

[0004] The purpose of this invention is to provide a method for pre-reinforcing a shield tunnel in a water-rich sand layer, which can achieve drilling through areas containing high-strength pipe piles and reduce the amount of water and sand inflow.

[0005] To achieve the above objectives, this invention provides a method for pre-reinforcement construction of a shield tunnel in a water-rich sand layer (MJS), comprising the following steps: (1) designing borehole locations within the foundation pit, constructing guide piers according to the borehole locations, with the guide piers closely attached to the retaining piles, laying out the borehole locations and installing flanges on the guide piers, and installing check valves on the flanges; (2) installing a pilot borehole machine within the foundation pit, closing the check valve, and drilling the pilot borehole machine through the retaining piles using a core drill to perform preliminary pilot borehole drilling; (3) removing the core drill, installing an outer casing on the pilot borehole machine, and using the outer casing for pilot borehole drilling. (3) Follow up with the hole and install an inner drill rod inside the outer sleeve on the hole-reaming machine. Continue to derive the hole to the designed depth through the inner drill rod. During the hole-reaming process, the inner drill rod injects double grout into the hole. (4) Pull out the inner drill rod, remove the hole-reaming machine, install an MJS grouting machine in the pit, install a grouting pipe on the MJS grouting machine, and install the grouting pipe to the designed depth. (5) Pull out the outer sleeve. (6) Pull back the grouting pipe through the MJS grouting machine, and spray grout through the grouting pipe. At the same time, remove the grouting pipe that has been withdrawn from the hole.

[0006] Preferably, in step (1), the guide pier is a C30 plain concrete pier.

[0007] Preferably, in step (1), the flange and the guide block are connected by bolts.

[0008] Preferably, in step (2), the diameter of the core drill is 219 mm.

[0009] Preferably, in step (3), the diameter of the outer sleeve is 219 mm, the diameter of the inner drill rod is 89 mm, and the diameter of the drill bit of the inner drill rod is 180 mm.

[0010] Preferably, in step (3), the diffusion radius of the dual grout is 1m, the filling rate is 20%, the water-cement ratio is 1:1, the cement-water glass ratio is 1:1, and the cutoff standard for injecting the dual grout is that the final grouting pressure reaches 3MPa.

[0011] Preferably, in step (6), the MJS grouting machine retracts the grouting pipe at a retraction speed of 20 min / m.

[0012] Preferably, the method further includes step (7), which involves sealing the opening of the duct after the grouting pipe has completed the grouting process.

[0013] Preferably, in step (7), the orifice is sealed with C30 plain concrete.

[0014] Compared with existing technologies, the MJS pre-reinforcement construction method for shield tunnels in water-rich sand layers of the present invention pre-sets guide piers on the retaining piles and uses a perforation-sealing device formed by flanges and check valves on the guide piers to prevent water inrush during subsequent drilling in the water-rich sand layer. Then, a core drill is used to drill through the retaining piles using a drilling machine, followed by the use of an outer casing and inner drill rod to advance the drilling, injecting dual grouts during the drilling process. This prevents hole collapse during drilling and reduces sand inrush. Therefore, the MJS pre-reinforcement construction method for shield tunnels in water-rich sand layers of the present invention can prevent hole collapse during drilling when passing under underground structures with pile groups, reduce water and sand inrush, and simultaneously enable drilling through areas containing high-strength pipe piles, improving pre-reinforcement quality, reducing the impact on underground structures and the surrounding environment, and significantly reducing the construction cost and time of such pre-reinforcement. It features convenient construction, short construction period, good drilling and reinforcement quality, low construction cost, simple process, and high safety. Attached Figure Description

[0015] Figure 1 This is an installation structure diagram of the flange and check valve in the MJS pre-reinforcement construction method for water-rich sand tunnels of the present invention.

[0016] Figure 2This is a construction drawing of the core drill passing through the retaining pile in the MJS pre-reinforcement construction method for water-rich sand tunnels of the present invention.

[0017] Figure 3 This is a construction drawing of the internal drill rod injection of double grout in the MJS pre-reinforcement construction method for water-rich sand tunnels according to the present invention.

[0018] Figure 4 This is a structural diagram of the grouting pipe installation in the MJS pre-reinforcement construction method for water-rich sand layer shield tunnels of the present invention.

[0019] Figure 5 This is a construction drawing of the MJS grouting machine during the back-extraction of the grouting pipe in the MJS pre-reinforcement construction method for water-rich sand tunnels of the present invention. Detailed Implementation

[0020] To illustrate the technical content and structural features of the present invention in detail, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0021] Example 1:

[0022] Please see Figures 1 to 5 The method for pre-reinforcement construction of MJS tunnels in water-rich sand layers according to the present invention includes the following steps:

[0023] S11, design the hole positions within the foundation pit 100, construct guide pier 1 according to the hole positions, and make guide pier 1 closely attached to retaining pile 2. After the guide pier 1 reaches the strength, lay out the hole positions and install flange 3 on the guide pier 1, and install check valve 4 on flange 3.

[0024] S12, Install the pre-drilling machine 5 in the foundation pit 100, close the check valve 4, and the pre-drilling machine 5 drills through the retaining pile 2 through the core drill 51 to carry out the preliminary pre-drilling;

[0025] S13, remove the core drill 51, install the outer sleeve 52 on the pre-drilling machine 5, use the outer sleeve 52 to advance the pre-drilling, and install the inner drill rod 53 located inside the outer sleeve 52 on the pre-drilling machine 5. Continue to advance the pre-drilling to the designed depth through the inner drill rod 53. During the pre-drilling process, the inner drill rod 53 injects double grout 54 into the duct to reinforce the grouting line.

[0026] S14, pull out the inner drill rod 53, remove the pilot hole machine 5, install the MJS grouting machine 6 in the foundation pit 100, install the grouting pipe 61 on the MJS grouting machine 6, and install the grouting pipe 61 to the design depth.

[0027] S15, pull out the outer tube 52;

[0028] S16, the grouting pipe 61 is pulled back by the MJS grouting machine 6, and grouting is sprayed through the grouting pipe 61. At the same time, the grouting pipe 61 that has been pulled back out of the duct is removed.

[0029] In step S11, the guide pier 1 is a C30 plain concrete pier with a thickness of 30-50cm and a smooth and flat working surface; in step S11, the flange 3 and the guide pier 1 are connected by bolts, and the retaining piles 2 include reinforcing piles 21 and existing piles 22, but are not limited thereto; in step S12, the diameter of the core drill 51 is 219mm, but is not limited thereto, and those skilled in the art can determine the diameter of the core drill 51 according to the actual situation; in step S13, the diameter of the outer sleeve 52 is 219mm, the diameter of the rod of the inner drill rod 53 is 89mm, and the diameter of the drill bit of the inner drill rod 53 is 180mm, but the outer sleeve... The diameter of 52 and the size of the inner drill rod 53 are not limited to these; in step S13, during the pilot hole process, the diffusion radius of the double grout 54 is 1m, the filling rate is 20%, the water-cement ratio is 1:1, the cement-water glass ratio is 1:1, and the cutoff standard for injecting the double grout 54 is that the final grouting pressure reaches 3Mpa; in step S16, the MJS grouting machine 6 pulls back the grouting pipe 61 at a speed of 20min / m. The grouting pipe 61 is equipped with a mud discharge valve, an underground pressure sensor, and a grouting nozzle. The specific principles of the mud discharge valve, the underground pressure sensor, and the grouting nozzle are well known to those skilled in the art. Grouting can form a pile body 7 within the water-rich sand layer 200 by spraying grout from the grouting pipe 61.

[0030] Example 2:

[0031] Please see Figures 1 to 5 The method for pre-reinforcement construction of MJS tunnels in water-rich sand layers according to the present invention includes the following steps:

[0032] S21, design the hole positions within the foundation pit 100, construct guide pier 1 according to the hole positions, and make guide pier 1 closely attached to retaining pile 2. After the guide pier 1 reaches the strength, lay out the hole positions and install flange 3 on the guide pier 1, and install check valve 4 on flange 3.

[0033] S22, Install a pre-drilling machine 5 in the foundation pit 100, close the check valve 4, and the pre-drilling machine 5 drills through the retaining pile 2 through the core drill 51 to carry out preliminary pre-drilling;

[0034] S23, remove the core drill 51, install the outer sleeve 52 on the pre-drilling machine 5, use the outer sleeve 52 to advance the pre-drilling, and install the inner drill rod 53 located inside the outer sleeve 52 on the pre-drilling machine 5. Continue to advance the pre-drilling to the designed depth through the inner drill rod 53. During the pre-drilling process, the inner drill rod 53 injects double grout 54 into the duct to reinforce the grouting line.

[0035] S24, pull out the inner drill rod 53, remove the pilot hole machine 5 by hoisting it away, install the MJS grouting machine 6 in the foundation pit 100, install the grouting pipe 61 on the MJS grouting machine 6, and install the grouting pipe 61 to the design depth;

[0036] S25, after the grouting pipe 61 is installed to the design depth, the outer sleeve 52 is pulled out section by section;

[0037] S26, after debugging all the equipment of MJS grouting machine 6, pull back the grouting pipe 61 through MJS grouting machine 6 and spray grout through the grouting pipe 61, and at the same time remove the grouting pipe 61 that has been pulled out of the duct.

[0038] S27, after the grouting pipe 61 has completed the grouting, the opening of the duct is sealed.

[0039] In step S21, the guide pier 1 is a C30 plain concrete pier with a thickness of 30-50cm and a smooth and flat working surface; in step S21, the flange 3 and the guide pier 1 are connected by bolts, and the retaining piles 2 include reinforcing piles 21 and existing piles 22, but are not limited thereto; in step S22, the diameter of the core drill 51 is 219mm, but is not limited thereto, and those skilled in the art can determine the diameter of the core drill 51 according to the actual situation; in step S23, the diameter of the outer sleeve 52 is 219mm, the diameter of the inner drill rod 53 is 89mm, and the diameter of the drill bit of the inner drill rod 53 is 180mm, but the diameter of the outer sleeve 52 and the size of the inner drill rod 53 are not limited thereto; in step S23, in the guide... During the drilling process, the diffusion radius of the double grout 54 is 1m, the filling rate is 20%, the water-cement ratio is 1:1, and the cement-to-water glass ratio is 1:1. The cutoff standard for injecting the double grout 54 is that the final grouting pressure reaches 3Mpa. In step S26, the MJS grouting machine 6 retracts the grouting pipe 61 at a retraction speed of 20min / m. The grouting pipe 61 is equipped with a mud discharge valve, an underground pressure sensor, and a grouting nozzle. The specific principles of the mud discharge valve, the underground pressure sensor, and the grouting nozzle are well known to those skilled in the art. Grouting can form a pile body 7 within the water-rich sand layer 200 by spraying grout through the grouting pipe 61. In step S27, the borehole opening is sealed with C30 plain concrete, the grouting pipe 61 is cleaned in time, and then transferred to the next borehole position. Steps S21 to S27 are repeated.

[0040] In summary, the MJS pre-reinforcement construction method for shield tunnels in water-rich sand layers of the present invention pre-sets guide piers 1 on the retaining piles 2, and sets up a perforated water-stopping device with flanges 3 and check valves 4 on the guide piers 1 to stop water in the subsequent pilot hole in the water-rich sand layer 200, thus preventing water inrush. Then, the pilot hole machine 5 first drills through the retaining piles 2 with a core drill 51, and then follows up with the pilot hole using an outer casing 52 and an inner drill rod 53, injecting double grout 54 during the pilot hole process. This can prevent hole collapse during the hole formation process and reduce the amount of sand inrush. Therefore, the MJS pre-reinforcement construction method for shield tunnels in water-rich sand layers of the present invention can prevent hole collapse during the drilling process when passing under underground structures and reduce the amount of water and sand inflow. At the same time, it can achieve drilling through areas containing high-strength pipe piles, improve the quality of pre-reinforcement, reduce the impact on underground structures and the surrounding environment, and greatly reduce the construction cost and construction period of this type of pre-reinforcement. It has the characteristics of convenient construction, short construction period, good drilling and reinforcement quality, low construction cost, simple process and high safety.

[0041] The above-disclosed examples are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are within the scope of the present invention.

Claims

1. A method for pre-reinforcement construction of MJS tunnels in water-rich sand layers, characterized in that, Includes the following steps: (1) Design the hole positions in the foundation pit, construct guide piers according to the hole positions, and make the guide piers close to the retaining piles. Perform hole layout and flange installation on the guide piers, and install check valves on the flanges. (2) Install a pilot hole machine in the foundation pit, close the check valve, and the pilot hole machine drills through the retaining piles with a core drill to perform preliminary pilot hole drilling; (3) Remove the core drill, install an outer sleeve on the pre-drilling machine, use the outer sleeve to perform pre-drilling and follow-up, and install an inner drill rod located inside the outer sleeve on the pre-drilling machine. Continue to pre-drill to the designed depth through the inner drill rod. During the pre-drilling process, the inner drill rod injects double slurry into the channel. (4) Pull out the inner drill rod, remove the pilot hole machine, install the MJS grouting machine in the foundation pit, install the grouting pipe on the MJS grouting machine, and install the grouting pipe to the design depth; (5) Pull out the outer sleeve; (6) The grouting pipe is pulled back by the MJS grouting machine, and the grouting pipe is sprayed with grout. At the same time, the grouting pipe that has been pulled back out of the duct is dismantled.

2. The method for pre-reinforcement construction of MJS tunnels in water-rich sand layers according to claim 1, characterized in that, In step (1), the guide pier is a C30 plain concrete pier.

3. The method for pre-reinforcement construction of MJS tunnels in water-rich sand layers according to claim 1, characterized in that, In step (1), the flange and the guide block are connected by bolts.

4. The method for pre-reinforcement construction of MJS tunnels in water-rich sandy layers according to claim 1, characterized in that, In step (2), the diameter of the core drill is 219 mm.

5. The method for pre-reinforcement construction of MJS tunnels in water-rich sand layers according to claim 4, characterized in that, In step (3), the diameter of the outer sleeve is 219 mm, the diameter of the inner drill rod is 89 mm, and the diameter of the drill bit of the inner drill rod is 180 mm.

6. The method for pre-reinforcement construction of MJS tunnels in water-rich sand layers according to claim 1, characterized in that, In step (3), the diffusion radius of the double grout is 1m, the filling rate is 20%, the water-cement ratio is 1:1, the cement-water glass ratio is 1:1, and the cutoff standard for injecting the double grout is that the final grouting pressure reaches 3MPa.

7. The method for pre-reinforcement construction of MJS tunnels in water-rich sandy layers according to claim 1, characterized in that, In step (6), the MJS grouting machine retracts the grouting pipe at a speed of 20 min / m.

8. The method for pre-reinforcement construction of MJS tunnels in water-rich sand layers according to claim 1, characterized in that, It also includes step (7), which involves sealing the opening of the duct after the grouting pipe has completed the grouting process.

9. The method for pre-reinforcement construction of MJS tunnels in water-rich sand layers according to claim 8, characterized in that, In step (7), the orifice is sealed with C30 plain concrete.

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