A construction method of a civil air defense door frame

Abstract

The application discloses a construction method of a civil air defense door frame, which is suitable for the construction condition that the installation height of the civil air defense door frame is greater than the net height of a two-way support to a raft slab of a deep foundation pit; the method is characterized in that: the raft slab upper skin steel bars are bent downward at the position of a civil air defense door sill and additional upper skin steel bars are arranged, two isolation structures are arranged on both sides of the door sill, the raft slab pouring area is divided into a raft slab first pouring area and a raft slab main body pouring area, the first pouring area concrete is poured to the bottom of a groove, and then the main body area is poured to the design elevation, thereby forming a door frame installation reserved groove; after the two-way support is removed, the civil air defense door frame is installed, and finally, the reserved groove is poured and compacted by using micro-expansion concrete with a strength grade higher than that of the raft slab. The application can effectively solve the problem that the civil air defense door frame cannot be pre-buried due to the limited space of the deep foundation pit, has the advantages of convenient construction, good structure integrity and crack resistance, and is suitable for the installation and construction of civil air defense door frames of various basements.

Description

Technical Field

[0001] This invention belongs to the field of building construction technology, and specifically relates to a construction method for civil defense door frames. Background Technology

[0002] Civil defense basements are important building structures specifically designed according to the protection requirements of civil defense projects and possessing strategic protection functions. Civil defense doors, as key protective facilities at the entrances and exits of civil defense projects, are classified into Level 5 and Level 6 according to their protection level. Their models and dimensions are determined based on the actual needs of the project, with threshold height typically ranging from 100mm to 2000mm.

[0003] In actual construction, air-raid shelter doors consist of a door frame and a door leaf. The door frame is made of one-piece molded angle steel, and conventional construction requires it to be poured simultaneously with the concrete of the base slab or wall panels. However, the height of the second support in a deep foundation pit limits the installation space for the air-raid shelter door frame, making it impossible to pre-embed the air-raid shelter door frame during the basement raft slab construction stage. Therefore, how to solve the problem of air-raid shelter door frame construction under space constraints has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] This invention addresses the deficiencies in existing technologies by providing a construction method for civil defense door frames.

[0005] The specific technical solution adopted by this invention is as follows:

[0006] A method for constructing a civil defense door frame, applicable to situations where the installation height of the civil defense door frame is greater than the net height of the raft foundation from the second layer of bracing in a deep foundation pit, characterized by comprising the following steps:

[0007] Step S1: At the corresponding position of the civil defense threshold, bend the top steel bar of the raft slab downwards according to the set ratio to form a groove structure, and add additional top steel bar in the bending area.

[0008] Step S2: At a predetermined distance on both sides of the civil defense threshold, a first isolation structure and a second isolation structure are set up respectively. The raft slab pouring area is divided into the raft slab pre-pouring area in the middle and the raft slab main body pouring area on both sides by the two isolation structures.

[0009] Step S3: Using a phased pouring method, first pour concrete in the raft slab pre-pouring area to the bottom of the groove structure, then pour concrete in the raft slab main body pouring area to the design elevation, so as to form a door frame installation reserved groove on the raft slab.

[0010] Step S4: After the second layer of support in the deep foundation pit is removed, the civil defense door frame is installed in the pre-reserved groove for the door frame installation.

[0011] Step S5: After the civil defense door frame installation passes the inspection, micro-expansion concrete is used as the post-cast concrete to fill the reserved groove for door frame installation.

[0012] Preferably, the first isolation structure consists of a wire mesh and a vertical steel bar support.

[0013] Preferably, the second isolation structure is composed of a quick-closing mesh and diagonal reinforcing bars.

[0014] Preferably, the angle iron at the bottom of the air-raid shelter door frame is anchored in the pre-reserved groove for door frame installation, and the angle iron at the top of the air-raid shelter door frame is anchored in the door frame beam.

[0015] Preferably, the strength grade of the post-cast micro-expansion concrete is higher than that of the raft foundation concrete.

[0016] Preferably, the predetermined distance is 90-110 mm.

[0017] Preferably, the top layer of steel bars on the raft slab is bent downwards at a ratio of 1:6.

[0018] Compared with the prior art, the present invention has at least one of the following advantages or beneficial effects:

[0019] This invention addresses the situation where the installation height of the civil defense door frame exceeds the net height of the raft foundation from the second layer of supports in a deep foundation pit. It utilizes steel bar bending, double-layer isolation, and staged pouring to create a pre-reserved groove for the door frame installation. After the supports are removed, the door frame is installed and sealed with high-grade micro-expansion concrete. This effectively solves the problem of limited space in deep foundation pits preventing the pre-embedding of civil defense door frames. The steel bar structure is reasonable, resulting in excellent structural integrity and crack resistance. The isolation structure is reliable, the process is simple and versatile, and the post-poured concrete is dense and shrinkage-free. The civil defense door frame, raft foundation, and door frame beam form an integral load-bearing structure, meeting the requirements for protective airtightness and structural safety in civil defense projects. The construction is convenient, economical, and yields significant results. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this specification, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention.

[0021] Figure 1 This is a structural schematic diagram of the construction of the civil defense door frame in an embodiment of the present invention;

[0022] In the diagram: 1-Air defense door frame; 2-Door frame beam; 3-Angle iron; 4-Secondary bracing; 5-Raft foundation concrete; 6-Raft foundation top reinforcement; 7-Additional top reinforcement; 8-Pre-reserved groove for door frame installation; 9-Wire mesh; 10-Reinforcement bracket; 11-Quick-closing mesh; 12-Diagonal tie reinforcement; 13-Pre-cast area of ​​raft foundation. Detailed Implementation

[0023] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.

[0024] like Figure 1 As shown, this embodiment discloses a construction method for a civil defense door frame. This method is applicable to situations where the installation height of the civil defense door frame 1 is greater than the net height of the raft foundation from the second layer of the deep foundation pit support 4. The construction method includes the following steps:

[0025] Step S1, Reinforcement treatment: At the corresponding position of the civil defense threshold, the top reinforcement 6 of the raft slab is bent downwards at a ratio of 1:6 (this ratio is the height-to-width ratio) to form a groove structure, and additional top reinforcement 7 is added in the bending area to improve the crack resistance of the concrete and make the raft slab reinforcement and the threshold reinforcement form a continuous whole.

[0026] Step S2, Isolation Structure: At 90-110mm on both sides of the air-raid shelter threshold, a first isolation structure and a second isolation structure are set up as temporary isolation measures. The first isolation structure consists of wire mesh 9 and vertical steel reinforcement support 10, and the second isolation structure consists of quick-closing mesh 11 and diagonal steel reinforcement 12. During construction, the first isolation structure is first made using wire mesh 9 and vertical steel reinforcement support 10, and then the second isolation structure is made using quick-closing mesh 11 and diagonal steel reinforcement 12. The two isolation structures divide the raft foundation pouring area into the raft foundation pre-pouring area 13 in the middle and the raft foundation main body pouring area on both sides.

[0027] Step S3, staged pouring: The concrete is poured in stages. First, the raft slab concrete 5 is poured to the bottom of the groove structure in the first pouring area 13 of the raft slab. Then, the concrete in the main pouring area of ​​the raft slab is poured to the design elevation (i.e., poured to the designed height of the raft slab surface layer). The door frame installation groove 8 is formed on the raft slab.

[0028] Step S4, installation of the civil defense door frame 1: After the deep foundation pit second support 4 is removed and the construction space meets the requirements, the civil defense door frame 1 is installed in the door frame installation reserved groove 8; the angle iron 3 at the bottom of the civil defense door frame 1 is anchored in the reserved groove, and the upper angle iron is fixed to the door frame beam 2. The position is corrected and the installation is inspected and qualified.

[0029] Step S5, Post-pouring sealing construction: Use micro-expansion concrete with a strength grade higher than raft slab concrete 5 as post-pouring concrete, and pour the reserved groove 8 for door frame installation into the whole and make it dense. After curing, the civil defense door frame 1, raft slab, and door frame beam 2 form an integral load-bearing structure to meet the requirements of civil defense project protection, airtightness and structural safety.

[0030] Engineering application verification shows that this method is simple to construct, has good pre-grooving quality, and high installation accuracy of the civil defense door frame 1. It can effectively solve the problem that the civil defense door frame 1 cannot be pre-embedded under the condition of limited support in deep foundation pits, and meets the construction and acceptance requirements of civil defense projects.

[0031] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.

Claims

1. A construction method for a civil defense door frame, the method being applicable to situations where the installation height of the civil defense door frame is greater than the net height of the raft foundation from the second layer of bracing in a deep foundation pit, characterized in that... Includes the following steps: Step S1: At the corresponding position of the civil defense threshold, bend the top steel bar of the raft slab downwards according to the set ratio to form a groove structure, and add additional top steel bar in the bending area. Step S2: At a predetermined distance on both sides of the civil defense threshold, a first isolation structure and a second isolation structure are set up respectively. The raft slab pouring area is divided into the raft slab pre-pouring area in the middle and the raft slab main body pouring area on both sides by the two isolation structures. Step S3: Using a phased pouring method, first pour concrete in the raft slab pre-pouring area to the bottom of the groove structure, then pour concrete in the raft slab main body pouring area to the design elevation, so as to form a door frame installation reserved groove on the raft slab. Step S4: After the second layer of support in the deep foundation pit is removed, the civil defense door frame is installed in the pre-reserved groove for the door frame installation. Step S5: After the civil defense door frame installation passes the inspection, micro-expansion concrete is used as the post-cast concrete to fill the reserved groove for door frame installation.

2. The construction method for the civil defense door frame according to claim 1, characterized in that, The first isolation structure consists of wire mesh and vertical steel reinforcement supports.

3. The construction method for the civil defense door frame according to claim 1, characterized in that, The second isolation structure consists of a quick-closing mesh and diagonal reinforcing bars.

4. The construction method for the civil defense door frame according to claim 1, characterized in that, The angle iron at the bottom of the air-raid shelter door frame is anchored in the pre-reserved groove for door frame installation, and the angle iron at the top of the air-raid shelter door frame is anchored in the door frame beam.

5. The construction method for the civil defense door frame according to claim 1, characterized in that, The strength grade of the post-cast micro-expansion concrete is higher than that of the raft foundation concrete.

6. The construction method for the civil defense door frame according to claim 1, characterized in that, The predetermined distance is 90–110 mm.

7. The construction method for the civil defense door frame according to claim 1, characterized in that, The top layer of steel bars on the raft slab is bent downwards at a ratio of 1:6.

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