Construction method for breaking shield obstacles below subway station through freezing and rotary cutting

Abstract

The invention relates to the technical field of shield construction, in particular to a construction method for breaking and removing shield obstacles below a subway station through freezing and rotary cutting, and the construction method comprises the following specific steps: forming uniformly distributed pilot tunnel structures around a stand column pile by positioning the position of the stand column pile and horizontally drilling by using a drilling machine; after pilot tunnel drilling is completed, freezing pipes are inserted immediately to freeze soil around the stand column piles; a plurality of guide holes are formed in the stand column pile, hole expanders are placed in the guide holes, and hole expanding is started upwards in sequence; according to the construction method, the soil within the range needing obstacle clearing can be frozen, the supporting performance of the soil during shield construction is improved, and collapse and existing station settlement are avoided; meanwhile, drilling is conducted on the stand column pile, a reamer is adopted to conduct rotary cutting and breaking on the stand column pile, and expansive cement mortar is poured, so that the bearing capacity of the foundation can be guaranteed; obstacles on the subway shield route are removed on the whole, and the influence on the existing station in the construction process is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of shield construction, and in particular to a construction method for breaking shield obstacles under a subway station by freezing and turning. Background Art

[0002] With the advancement of urbanization, there are more and more construction scenarios such as subway line expansion and line crossing. However, for the early-constructed subways or the original subway buildings involved in the re-planning, column piles that were not removed during the original construction process will be stranded under the subway stations, affecting and hindering the construction shield of the new subway stations.

[0003] During the reverse construction of deep foundation pits of underground rail transit stations, the base will rebound and bulge. Therefore, column piles are needed to transfer the station structure's own load from the columns to the foundation, reducing the impact of unloading on the bearing layer during large excavation. This can effectively control the uplift of the foundation pit. After the subway station is built, these steel column piles will not be removed, resulting in the inability of the shield machine to pass through when the subway plans new subway lines in the future.

[0004] To sum up, considering the need to clear the column piles on the shield route of the new subway tunnel, and the need to reduce the impact on the existing station during the clearance process to prevent the existing station from settling during the construction process; in view of this, we propose a construction method of freezing and turning to break the shield obstacles under the subway station. Summary of the invention

[0005] The purpose of the present invention is to solve the deficiencies mentioned in the above background technology and to provide a construction method for breaking shield obstacles under a subway station by freezing and turning.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A construction method for breaking shield obstacles under a subway station by freezing and turning, the specific steps of the construction method are:

[0008] Step 1: Positioning: According to the existing subway station design drawings and construction status, determine the location of the column piles on the shield area path of the new subway station;

[0009] Step 2: Drilling of pilot holes: Use a drilling rig to drill holes horizontally in the vicinity of the new subway station and the existing subway station to form a uniformly distributed pilot hole structure around the column piles;

[0010] Step 3: Freeze the soil. After the pilot hole is drilled, insert the freezing pipe immediately to freeze the soil around the column piles to prevent the station from settling during the clearance process.

[0011] Step 4: Drilling of pilot holes: On the shield area path of the new subway station, according to the position of the column piles, in the vicinity of the new subway station and the existing subway station, use a drilling rig to drill horizontally through the column piles, perform construction in interval cycles, and open multiple pilot holes on the column piles;

[0012] Step 5: Single pile hole enlargement and obstacle removal: Place the hole enlarger in the guide hole of a single row of column piles, and start enlarging the holes from the bottom guide hole upwards. After each level of hole enlargement is completed, irrigate the area with expanded cement mortar; repeat step by step upwards to clear the column piles at that position;

[0013] Step 6: Expand and clear the entire area. Repeat step 5 to expand and clear all the pillars and piles in the shield area.

[0014] Preferably, the inner diameter of the guide tunnel is set to 10-30 cm.

[0015] Preferably, the vertical spacing between adjacent guide holes is 80-120 cm, and the horizontal spacing is 80-120 cm.

[0016] Preferably, the inner diameter of the guide hole is 10-30 cm, and the center distance between adjacent guide holes is not greater than the maximum reaming diameter of the reamer.

[0017] Preferably, the reamer is a hydraulic reamer.

[0018] Preferably, the maximum reaming diameter of the reamer is 1000-1500 mm.

[0019] Preferably, the expansive cement mortar adopts M2.5 type expansive cement mortar.

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

[0021] The construction method of freezing and cutting to break the shield obstacles under the subway station can freeze the soil within the range that needs to be cleared, improve the supporting performance of the soil during shield construction, and avoid collapse and settlement of the existing station; at the same time, by drilling holes in the shield crossing area, and using a hole expander to cut and break the column piles, and finally re-injecting expansive cement mortar, the bearing capacity of the foundation can be guaranteed; that is, the subway shield route is cleared as a whole, and the impact on the existing station during the construction process is reduced, preventing the station from settling, and the method is practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0023] Figure 1This is one of the schematic diagrams of the construction hole positions of the present invention;

[0024] Figure 2 This is the second schematic diagram of the construction hole position of the present invention.

[0025] The meaning of each number in the figure is:

[0026] 1. Existing subway station; 2. Guide tunnel; 3. Guide hole; 4. Column piles; 5. New subway station. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0028] See also Figure 1-2 The present invention describes the above technical solution in detail through the following embodiments:

[0029] A construction method for breaking shield obstacles under subway stations by freezing and turning. Figure 1 , 2 The construction hole structure shown in the figure, the specific steps of the construction method are as follows:

[0030] Step 1: Positioning: According to the design drawings and construction status of the existing subway station 1, determine the position of the column piles 4 on the shield area path of the new subway station 5, and determine the number and position of the openings of the guide tunnel 2 according to the specifications of the column piles 4;

[0031] Step 2: Drilling of pilot holes: Use a drilling rig to drill horizontally at the adjacent part of the new subway station 5 and the existing subway station 1. In this embodiment, the inner diameter of the pilot hole 2 is set to 20 cm, and the upper and lower spacings of adjacent pilot holes 2 are set to 100 cm, and the horizontal spacing is 100 cm. A uniformly distributed pilot hole 2 structure is formed around the column piles 4. During the drilling process, the verticality of the drill bit and the wall is maintained to ensure the drilling quality.

[0032] Step 3: Freeze the soil. After the pilot hole 2 is drilled, immediately insert a freezing pipe to freeze the soil around the column pile 4 to prevent the station from settling during the clearance process and prevent the pilot hole 2 from collapsing.

[0033] Step 4: Drilling of guide holes. On the shield area path of the newly built subway station 5, determine the corresponding position of the column pile 4 that hinders the shield. At the adjacent walls of the newly built subway station 5 and the existing subway station 1, use a drilling rig to drill horizontally through the column pile 4, perform interval cyclic construction, and open a guide hole 3 on the column pile 4. The guide holes 3 of this embodiment adopt a top-down arrangement structure. In order to maintain stress stability, an interval construction method is adopted, that is, the construction sequence of the first, third, second, and fourth from top to bottom is adopted. The inner diameter of the guide hole 3 of this embodiment is 20 cm, and the center spacing of adjacent guide holes 3 is not greater than the maximum reaming diameter of the reamer, and the reamer adopts a hydraulic reamer with a maximum reaming diameter of 1200 mm.

[0034] Step 5: Single pile hole expansion and obstacle removal, put the reamer into the guide hole 3 of a single row of column piles 4, and start reaming from the bottom guide hole 3 upward in sequence, and start reaming from the bottom guide hole 3. After completing the first stage of hole expansion, pour M2.5 expansive cement mortar in time; lift the reamer to the second guide hole 3 from bottom to top, repeat the second stage of hole expansion and inject M2.5 expansive cement mortar, and repeat step by step upward until the single row of column piles in the shield crossing area is cleared;

[0035] Step 6: Expand and clear the entire area. Repeat step 5 to expand and clear all the column piles 4 in the shield area.

[0036] It should be noted that the present invention adopts the method of freezing soil to improve the bearing capacity of soil during construction, and adopts the drilling-expansion method to cut and break the column piles 4 in the shield crossing area, clear the subway tunnel shield crossing area, and timely fill the expansive cement mortar to keep the structure of the construction area stable, which can minimize the impact on the existing station during the construction process and prevent the station from settling.

[0037] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0038] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A construction method for removing shield obstacles under a subway station by freezing and turning, characterized in that: The specific steps of the construction method are: Step 1: Positioning: According to the design drawings and construction status of the existing subway station (1), determine the position of the column piles (4) on the shield area path of the new subway station (5); Step 2: Drilling of pilot holes: using a drilling rig to drill horizontal holes adjacent to the newly built subway station (5) and the existing subway station (1) to form a uniformly distributed pilot hole (2) structure around the column piles (4); Step 3: Freeze the soil. After the pilot hole (2) is drilled, immediately insert a freezing pipe to freeze the soil around the column pile (4) to prevent the station from settling during the clearance process. Step 4: Drilling of guide holes: On the shield tunneling area path of the new subway station (5), according to the position of the column pile (4), in the vicinity of the new subway station (5) and the existing subway station (1), a drilling rig is used to drill horizontally through the column pile (4), and the construction is carried out in interval cycles to open a plurality of guide holes (3) on the column pile (4); Step 5: Single pile hole enlargement and obstacle removal: Place the hole enlarger in the guide hole (3) of a single row of column piles (4), and start enlarging the holes from the bottom guide hole (3) upwards in sequence. After each level of hole enlargement is completed, irrigate the area with expanded cement mortar; repeat step by step upwards to clear the column piles (4) at that position; Step 6: Expand and clear the entire area. Repeat step 5 to expand and clear all the pillar piles (4) in the shield area.

2. The construction method for removing shield obstacles under a subway station by freezing and turning as claimed in claim 1, characterized in that: The inner diameter of the guide hole (2) is set to 10-30 cm.

3. The construction method for removing shield obstacles under a subway station by freezing and turning as claimed in claim 2, characterized in that: The vertical spacing between adjacent guide holes (2) is 80-120 cm, and the horizontal spacing is 80-120 cm.

4. The construction method for removing shield obstacles under a subway station by freezing and turning as claimed in claim 1, characterized in that: The inner diameter of the guide hole (3) is 10-30 cm, and the center distance between adjacent guide holes (3) is not greater than the maximum reaming diameter of the reamer.

5. The construction method for breaking shield obstacles under a subway station by freezing and turning as claimed in claim 4, characterized in that: The reamer is a hydraulic reamer.

6. The construction method for breaking shield obstacles under a subway station by freezing and turning as claimed in claim 4, characterized in that: The maximum reaming diameter of the reamer is 1000-1500mm.

7. The construction method for removing shield obstacles under a subway station by freezing and turning as claimed in claim 1, characterized in that: The expansive cement mortar adopts M2.5 type expansive cement mortar.

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