Temporary duct piece weakening method in shield method contact channel construction

Abstract

The invention relates to the technical field of contact channel construction, in particular to a temporary duct piece weakening method in shield method contact channel construction, which comprises the following steps: step 1, firstly manufacturing a peripheral framework, and reserving a position to be cut on the peripheral framework; 2, peripheral segment concrete is poured on the peripheral framework except the position to be cut, and peripheral segments are formed; thirdly, after the peripheral segment concrete reaches the specified strength, cutting part concrete is poured in the to-be-cut position, a cutting part segment is formed, and after the cutting part concrete reaches the specified strength, the whole segment is manufactured; and step 4, punching the cutting part of the segment at the to-be-cut position on the segment to form a plurality of holes. Concrete with different strengths is poured in the peripheral framework and the to-be-cut position respectively, so that the temporary duct piece at the hole is easy to cut under the condition of ensuring the safety and stability of the structure, the construction period is short, and the cutting efficiency of the temporary duct piece in the shield method contact channel construction is improved.

Description

Technical Field

[0001] The invention relates to the technical field of connecting channel construction, and in particular to a temporary pipe segment weakening method in connecting channel construction using a shield method. Background Art

[0002] As urban underground space tends to develop in a grid-like manner, the construction demand for communication channels is very large as an important way to achieve interconnection and safety of underground space. The traditional method of communication channel construction is mining excavation and soil reinforcement by freezing method. This method is relatively mature and has rich construction experience, but its shortcomings are also very obvious, such as high cost of bottom reinforcement, easy to thaw and sink, and difficulty in freezing long-distance communication channel construction. Mechanical method of connecting channel construction technology is an emerging construction method in recent years. The construction method is to arrange a small-diameter shield machine horizontally in the main tunnel at one end, and use a full-process closed excavation method to excavate the connecting channel. Compared with the mining method excavation, it has the advantages of short construction period, low engineering cost and high safety. However, the construction of the shield method connecting channel inevitably requires cutting of tunnel segments. During the construction of the shield method connecting channel, the temporary segments at the entrance are difficult to cut. There are problems such as long excavation period, difficult to control the shield machine posture, and high risk of water and sand gushing during construction. However, research on solutions to this problem is still lacking. On the basis of ensuring the safety of the structure during construction and use, how to weaken the temporary segments, shorten the construction time, and improve the safety of the project needs to be solved urgently. Summary of the invention

[0003] The technical problem to be solved by the present invention is: in order to solve the problem that the pipe segments at the connecting channel are difficult to cut, the present invention provides a method for weakening temporary pipe segments in the construction of the connecting channel using the shield method to solve the above problem. The technical solution adopted by the present invention to solve its technical problems is: a temporary segment weakening method in the construction of a shield-based communication channel, comprising the following steps: step one, skeleton prefabrication, firstly making an outer skeleton, the outer skeleton having a position to be cut reserved; step two, outer casting, casting outer segment concrete on the outer skeleton outside the position to be cut to form an outer segment; step three, casting at the position to be cut, after the outer segment concrete reaches a specified strength, casting a cutting part concrete at the position to be cut, a heating wire is pre-embedded in the cutting part concrete to form a cutting part segment, and after the cutting part concrete reaches the specified strength, the entire segment is completed; step four, segment processing, before the shield machine is cut, the cutting part segment at the position to be cut on the segment is punched to form a plurality of holes. Preferably, in step one, a plurality of main reinforcement bars are tied to the position to be cut.

[0004] Preferably, in step one, the outer frame is a steel frame.

[0005] Preferably, the main reinforcement is glass fiber reinforcement.

[0006] Preferably, in step three, the strength grade of the outer segment concrete is greater than the strength grade of the cut portion concrete, and the cut portion concrete is glass concrete made of glass as aggregate.

[0007] Preferably, in step three, the concrete grade of the cutting part is C25, wherein the mass proportion of glass as aggregate is less than 20%.

[0008] Preferably, in step 4, the hole is a circular hole and the depth is less than the thickness of the pipe segment, that is, the hole does not penetrate the pipe segment.

[0009] Preferably, in step four, the plurality of holes are evenly arranged at intervals between the plurality of main ribs.

[0010] Preferably, the heating wire is used to heat the glass concrete. When the heating rate is greater than 20°C / min, after heating to 800°C and maintaining for 2 hours, the tensile strength decreases by more than 80%. The beneficial effects of the present invention are as follows: by reserving positions to be cut on the outer frame, and pouring concrete of different strengths on the outer frame and the positions to be cut respectively, the temporary pipe segments at the tunnel entrance can be easily cut while ensuring the safety and stability of the structure; the construction period is short, and the shield machine posture is easy to control, thereby improving the cutting efficiency of temporary pipe segments in the construction of shield tunneling communication channels; by pouring glass concrete at the positions to be cut, the strength of the cut part of the concrete can be maintained without heating, thereby ensuring the safety and stability of the overall structure of the tunnel; when the temporary pipe segments need to be removed, the glass concrete can be heated by the pre-buried electric heating wire, so that the structural strength of the cut part of the concrete can be quickly reduced, thereby facilitating the drilling and removal of the temporary pipe segments, thereby improving the construction efficiency and reducing the manufacturing cost of the temporary pipe segments. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0012] Figure 1 It is a schematic diagram of the prefabricated tube segment structure of the present invention; Figure 2 is a schematic diagram of the structure of the peripheral segment of the present invention; Figure 3 It is a structural schematic diagram of the main reinforcement of the present invention; Figure 4 is a schematic diagram of the positions of the holes of the present invention; Figure 5 It is a schematic diagram of the internal structure of the hole of the present invention.

[0013] Reference numerals: 1. Cutting part of the segment; 2. Peripheral segment; 3. Main reinforcement; 4. Hole. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] The following first describes the concepts involved in the present application in conjunction with the accompanying drawings. It should be noted that the following description of each concept is only to make the content of the present application easier to understand, and does not limit the scope of protection of the present application; at the same time, the embodiments and features in the embodiments of the present application can be combined with each other in the absence of conflict. The present application will be described in detail with reference to the accompanying drawings and in conjunction with the embodiments.

[0016] like Figures 1 to 5 As shown, the present invention provides an embodiment of a method for weakening a temporary segment in shield tunnel construction, comprising the following steps: Step 1: prefabricate the skeleton. First, make an outer skeleton. The outer skeleton adopts a steel skeleton. The steel skeleton can be made of steel bars or mold casting. The outer skeleton has reserved positions to be cut. In this embodiment, the positions to be cut are circular holes and are located near the center of the outer skeleton. In some other embodiments, the shape of the positions to be cut and the reserved positions can be adjusted accordingly according to actual needs.

[0017] A plurality of main reinforcement bars 3 are tied to the position to be cut, so as to facilitate the subsequent concrete pouring at the position to be cut and prevent the concrete from detaching from the pipe segment after the pouring is completed. The main reinforcement bars 3 are glass fiber reinforcements. Since the main reinforcement bars 3 are very important structures of the pipe segment, premature cutting and cleaning will damage the pipe segment structure and the tunnel, causing accidents. Therefore, the main reinforcement bars 3 cannot be cut and cleaned in advance. In this embodiment, 16 mm glass fiber reinforcements are used, which can not only ensure safety but also reduce the difficulty of cutting. Moreover, because the diameter of the glass fiber reinforcement is small, the risk of blockage after the glass fiber reinforcement is cut is reduced.

[0018] Step 2: pouring the outer periphery, pouring the outer segment concrete on the outer periphery skeleton outside the position to be cut to form the outer segment 2.

[0019] Step three, pouring the position to be cut. After the outer segment concrete reaches the specified strength, pour the cutting part concrete at the position to be cut. A heating wire is pre-embedded in the cutting part concrete. The heating wire is used to heat the glass concrete to form the cutting part segment 1. After the cutting part concrete reaches the specified strength, the entire segment is completed.

[0020] The strength grade of the outer segment concrete is greater than the strength grade of the cutting part concrete. On the one hand, the overall strength of the segment can be improved through the outer segment concrete. On the other hand, pouring the cutting part concrete with a low strength grade at the cutting position also facilitates the shield machine to cut the segment at the cutting position. In this embodiment, the cutting part concrete grade is C25. In this embodiment, the cutting part concrete is glass concrete made of glass as aggregate, wherein the mass of glass as aggregate accounts for less than 20%. This strength concrete can reduce the difficulty of cutting while ensuring safety. Specifically, when the heating rate is greater than 20°C / min, after heating to 800°C and maintaining for 2 hours, its tensile strength decreases by more than 80%.

[0021] In other embodiments, the mass of glass used as aggregate accounts for 20% to 40%. Using more glass as aggregate can further reduce the tensile strength of the concrete of the cut part. However, compared with this embodiment, the concrete of the cut part with more glass added is more affected by temperature. Therefore, it is suitable for sites with small temperature differences and suitable temperatures, so as to achieve the effect of quickly reducing the strength of the temporary pipe segment.

[0022] Step 4: Segment processing. After the segment is manufactured, the drilling positions are marked on the surface of the segment to avoid damage to the main reinforcement 3 during drilling. Before the shield machine is cut, the cutting portion of the segment 1 at the cutting position on the segment is punched to form a plurality of holes 4. The holes 4 are circular holes and the depth is less than the thickness of the segment, that is, the holes 4 do not penetrate the segment. The plurality of holes 4 are evenly arranged at the intervals between the plurality of main reinforcements 3. In this embodiment, the diameter of the hole 4 is 80 mm and the hole depth is 150 mm. The size of the hole 4 can be adjusted accordingly according to the density of the main reinforcement 3 binding. It is sufficient to keep the depth of the hole 4 greater than the diameter of the hole 4. This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and its core ideas of this application. The above are only preferred implementation methods of this application. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the concept and technical solution of the invention to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A method for weakening temporary segments in shield tunnel construction, characterized in that: The following steps are involved: Step 1: Prefabricate the skeleton. First, make the outer skeleton, and reserve the position to be cut. Step 2: pouring the outer segment concrete on the outer frame outside the position to be cut, to form the outer segment (2); Step 3: Casting the position to be cut. After the outer segment concrete reaches a specified strength, cast the cutting part concrete at the position to be cut. A heating wire is pre-embedded in the cutting part concrete to form a cutting part segment (1). After the cutting part concrete reaches a specified strength, the entire segment is completed. Step 4: Segment processing: Before the shield machine cuts, the cutting portion of the segment (1) at the position to be cut on the segment is punched to form a plurality of holes (4).

2. The method for weakening temporary segments in shield tunnel construction as claimed in claim 1, characterized in that: In step one, a plurality of main reinforcement bars (3) are tied to the position to be cut.

3. The method for weakening temporary segments in shield tunnel construction as claimed in claim 1, characterized in that: In step one, the outer frame is a steel frame.

4. The method for weakening temporary segments in shield tunnel construction as claimed in claim 2, characterized in that: The main reinforcement (3) is a glass fiber reinforcement.

5. The method for weakening temporary segments in shield tunnel construction as claimed in claim 1, characterized in that: In step three, the strength grade of the outer segment concrete is greater than the strength grade of the cut portion concrete, and the cut portion concrete is glass concrete made of glass as aggregate.

6. The method for weakening temporary segments in shield tunnel construction as claimed in claim 5, characterized in that: In step three, the concrete grade of the cut part is C25, wherein the mass proportion of glass as aggregate is less than 20%.

7. The method for weakening temporary segments in shield tunnel construction as claimed in claim 1, characterized in that: In step 4, the hole (4) is a circular hole and its depth is less than the thickness of the pipe segment, that is, the hole (4) does not penetrate the pipe segment.

8. The method for weakening temporary segments in shield tunnel construction as claimed in claim 2, characterized in that: In step four, the plurality of holes (4) are evenly arranged at intervals between the plurality of main ribs (3).

9. The method for weakening temporary segments in shield tunnel construction as claimed in claim 6, characterized in that: The heating wire is used to heat the glass concrete. When the heating rate is greater than 20°C / min, after being heated to 800°C and maintained for 2 hours, the tensile strength thereof decreases by more than 80%.

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