A construction method for segmentally filling concrete in a narrow space with a circular arc cross section

Abstract

The application relates to the technical field of building construction, in particular to a construction method for filling concrete in a narrow circular-section space in sections, which specifically comprises the following steps: S1, preparing concrete for pouring and preparing a formwork for closing an arc-shaped guide channel, the formwork being provided with side support plates for being arranged on the arc-shaped guide channel; S2, cleaning the base surface of the arc-shaped guide channel, and then closing the formwork on the top surface of the arc-shaped guide channel, and erecting a support in the box culvert on the top surface of the formwork; S3, pouring concrete from both ends of the top of the box culvert, and filling the poured arc-shaped guide channel with the concrete from the narrow circular-section space until the concrete is flush with the top of the box culvert; and S4, after the concrete solidifies, sequentially removing the support and the formwork. The application guarantees the integrity and connecting rigidity of the whole prefabricated box culvert in the pipe piece, improves the construction quality of the track structure, and is convenient to pour.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building construction, in particular to a concrete segmented filling construction method for a circular arc section narrow space. BACKGROUND

[0002] With the continuous development and expansion of national infrastructure, and influenced by factors such as environmental conditions along the line and ground transportation, the use of tunnel construction methods when entering urban areas or crossing large rivers and seas by railways and the like has gradually become a trend. Shield tunnel construction technology has the advantages of small influence on the surrounding environment, high degree of mechanization, controllable construction period, and is widely used in urban area and underwater tunnel engineering construction.

[0003] At present, from the development status of prefabrication technology, tunnel and underground engineering support prefabrication technology is mainly developed from two aspects: one is partial prefabrication technology; the second is full prefabrication technology, which is currently mainly applied in shield construction projects, of which the shield tunnel is a typical representative of prefabricated assembly lining.

[0004] However, the box culvert structure of the whole prefabrication assembly is usually connected in the segment, which usually involves the joint of different materials (such as steel and concrete, concrete and steel bars, etc.), and these parts are easily affected by external environment (such as temperature change, humidity change, etc.), which leads to aging, corrosion or fatigue of the materials, and further affects the durability of the overall structure, and is time-consuming and laborious to install, thereby causing the problem of low splicing efficiency of the box culvert in the segment.

[0005] The above content is only used to assist in understanding the technical solutions of the present application, and does not represent the acknowledgement of the above content as the closest prior art. SUMMARY

[0006] The purpose of the present application is to solve the above-mentioned deficiencies, and to provide a concrete segmented filling construction method for a circular arc section narrow space.

[0007] In order to solve the above technical problems, the present application adopts the following technical scheme: a concrete segmented filling construction method for a circular arc section narrow space, the gap between the segment and the box culvert constitutes a circular arc section narrow space, the two sides and the bottom of the box culvert are respectively provided with side arc plates and bottom arc plates, and arc-shaped guide grooves are arranged on the side arc plates and the bottom arc plates;

[0008] The construction method specifically comprises the following steps:

[0009] S1, preparing the concrete for pouring, and preparing the formwork for closing the arc-shaped guide groove, the formwork is provided with side support plates at both ends for being erected on the arc-shaped guide groove;

[0010] S2, clean the base surface of the arc-shaped guide groove, and then seal the formwork on the top surface of the arc-shaped guide groove, and erect the support on the top surface of the formwork in the box culvert;

[0011] S3, pour concrete from both ends of the top of the box culvert, and fill the sealed arc-shaped guide groove with concrete from the narrow space of the circular arc section until the concrete is flush with the top of the box culvert;

[0012] S4, after the concrete solidifies, sequentially remove the support and the formwork.

[0013] Further, in step S2, the base surface of the box culvert is cleaned and moistened before pouring the concrete.

[0014] Further, before pouring the concrete in step S3, a gas bag is used to seal the gap of 5 cm between the front end of the box culvert and the segment in the arc-shaped guide groove of the third ring box culvert among every three ring box culverts.

[0015] Further, the support includes a first adjusting rod arranged on the formwork, a top plate arranged on the first adjusting rod and vertically supported on the top surface of the inner cavity of the box culvert, and two second adjusting rods symmetrically arranged on the top plate and obliquely supported close to the first adjusting rod.

[0016] Further, the formwork is further provided with an exhaust hole for exhausting air in the cavity during pouring and observing the pouring condition of the concrete.

[0017] Further, four core sample holes are drilled at the bottom of one ring of the box culvert for core sample detection.

[0018] Compared with the prior art, the present application has the following beneficial effects: the present application combines the box culvert of overall prefabrication, the segment of staggered joint assembly with concave-convex tenon, and the construction method of segmented filling of concrete in the narrow space of the circular arc section, realizes the synchronous construction of the track structure and the shield, improves the on-site construction efficiency of the track structure, guarantees the integrity and connection stiffness of the box culvert of overall prefabrication in the segment, and improves the construction quality of the track structure; in the aspect of formwork technology, the customized steel formwork is used for construction, the overall quality of construction is good, and the appearance quality after pouring is good; in the aspect of concrete pouring, the chute is used to pour along the arc surface from the pouring gap of the box culvert, the pouring method is convenient, fast, and good in flowability, and can obviously reduce the generation of air bubbles. BRIEF DESCRIPTION OF DRAWINGS

[0019] The drawings accompanying the specification of this application form a part hereof, serve to provide further understanding of the application, and together with the description of the exemplary embodiments of the application given below, explain the application. In the drawings:

[0020] Figure 1 A front plan view of a structure of a segment and a gap filling concrete of a box culvert according to an embodiment of the present application;

[0021] Figure 2 A distribution diagram of core holes according to an embodiment of the present application;

[0022] Figure 3 A perspective view of a box culvert according to an embodiment of the present application;

[0023] Figure 4 A perspective view of a template and a support according to an embodiment of the present application.

[0024] In the figure: 1, segment; 2, box culvert; 21, side arc plate; 22, bottom arc plate; 23, arc-shaped guide groove; 3, template; 31, support; 311, first adjusting rod; 312, top plate; 313, second adjusting rod. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The embodiments in the present application and the features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0026] It should be noted that if the embodiments of the present application 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 condition, etc. between the components in a certain posture, and if the certain posture changes, the directional indications also change accordingly.

[0027] In addition, if the embodiments of the present application involve descriptions of “first”, “second”, etc., the descriptions of “first”, “second”, etc. are only for description purposes, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by “first” and “second” can explicitly or implicitly include at least one of the features. In addition, the meaning of “and / or” appearing throughout the text includes three parallel schemes. Taking “A and / or B” as an example, it includes A scheme, or B scheme, or A and B schemes. In addition, “multiple” means two or more. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the fact that a person skilled in the art can realize it. When the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection claimed by the present application.

[0028] AsFigures 1-4 As shown, the present application is a kind of arc section narrow space concrete segmented filling construction method, the gap between segment 1 and box culvert 2 constitutes the arc section narrow space, the two sides and bottom of the box culvert 2 are respectively provided with side arc plate 21 and bottom arc plate 22, and arc guide groove 23 is arranged on the side arc plate 21 and the bottom arc plate 22.

[0029] In the specific implementation, the whole prefabricated box culvert 2 is used to form the tunnel under-track structure in the segment 1 of the shield tunnel, and the under-track structure is assembled and constructed synchronously with the shield, wherein the side arc plate 21 and the bottom arc plate 22 of the prefabricated box culvert 2 and the side wall are holed, and the arc guide groove 23 is left in the holed side arc plate 21 and the bottom arc plate 22 of the under-track structure, and then the arc section narrow space formed between the box culvert 2 and the segment 1 is backfilled with concrete.

[0030] It should be noted that the prefabricated whole box culvert 2 has a strength grade C40, and the maximum weight of a single block is about 38.2t; the whole prefabricated ditch, cable groove and longitudinal beam have a strength grade C30; the under-track filling cushion layer is C25 concrete; the ditch cover plate and the cable groove cover plate are prefabricated C35 waterproof reinforced concrete cover plates.

[0031] It should be noted that the segment 1 is composed of 9 segment rings (43.2°×8+14.4°×1), the maximum weight of a single block is about 13.7t, the inner diameter is φ12.2m, the outer diameter is φ13.3m, the thickness is 550mm, and the width is 2000mm (average).

[0032] Moreover, the longitudinal joint on the segment ring block is provided with a tongue and groove, and the joints are assembled in a staggered manner, the top block is assembled by first overlapping 1350mm and then pushing longitudinally, the connection between the segments 1 is a 10.9 grade M36 high-grade inclined bolt connection, the material is C60 reinforced concrete (mixed with polypropylene reticular fiber, 1.8kg / m 3 ), and the impermeability grade is not less than P12.

[0033] The construction method specifically includes the following steps:

[0034] S1, prepare the concrete for pouring, and prepare the formwork 3 for closing the arc guide groove 23, the formwork 3 is provided with side support plates at both ends for being overlapped on the arc guide groove 23;

[0035] S2, clean the base surface of the arc guide groove 23, and then close the formwork 3 on the top surface of the arc guide groove 23, and the support 31 in the box culvert 2 is erected on the top surface of the formwork 3;

[0036] S3, pouring concrete from both ends of the top of the box culvert 2, the concrete from the narrow space of the circular arc section enters and fills the blocked arc guide groove 23, until the concrete is flush with the top of the box culvert 2;

[0037] In this way, by setting a narrow space of circular arc section on both sides of the top of the box culvert 2 close to the pipe piece 1, a self-made movable chute is connected to pour C40 self-compacting concrete along the arc from the gap on both sides of the box culvert 2, and the concrete is poured on both sides in turn.

[0038] S4, after the concrete solidifies, the support 31 and the formwork 3 are removed in turn.

[0039] In the specific implementation, in step S1, the mix proportion of the self-compacting concrete is determined according to the design drawing requirements and relevant regulations, and after performance testing, C40 self-compacting concrete is determined to be used, and the selected proportion is approved after testing, and the performance indicators are within the design range;

[0040] The formwork 3 and the support 31 combined with the formwork 3 are also prepared as shown. Figure 4

[0041] In step S2, in order to ensure the quality of the backfill concrete pouring of the box culvert 2, the foundation surface of the box culvert 2 is cleaned and moistened before pouring the concrete;

[0042] Then, after the steel bars are bound in the middle hole of the box culvert 2 (i.e. the arc guide groove 23 left on the bottom arc plate 22), the formwork 3 is set, and the formwork 3 is sealed with a 5mm thick customized steel mold. The formwork 3 and the side support plates at both ends of the formwork 3 are used to cover the holes on both sides and the bottom of the box culvert 2, each formwork 3 is provided with a support 31, one end of which is on the formwork 3 and the other end is on the box culvert 2, and each box culvert 2 can be provided with two rows of supports 31, and each row of supports 31 is 15cm away from the inside of the hole.

[0043] It should be noted that the steel mold must be checked for flatness and cleanliness before the formwork 3 is installed, and the steel mold must be polished and coated with a release agent before the formwork 3 is installed.

[0044] In step S3, before pouring, the amount of concrete poured at a time is calculated; the volume of C40 self-compacting concrete filled in each ring of the box culvert 2 is 4.843m 3 , and the volume of C40 self-compacting concrete filled in every three rings is 14.529m 3 , the specific calculation is as follows: the volume of concrete filled in the gap between each ring of the box culvert 2 and the pipe piece 1 (i.e. the narrow space of the circular arc section) is V1=10.68×0.15×2=3.204m 3 ​; The volume of the filled concrete on the bottom arc plate 22 hole of each ring box culvert 2 (i.e. the arc-shaped guide groove 23) is V2 = (2.8-0.11) x 1.08 x 0.25 = 0.7263 m 3 ; The volume of the filled concrete on the two side arc plates 21 holes of each ring box culvert 2 (i.e. the arc-shaped guide groove 23) is V3 = 2 x (1.8 x 0.11) x 1.08 x 0.25 = 0.9126 m 3 ;

[0045] Then, before the concrete is delivered, the temperature, slump spread, spread time T500, air content and other properties of the self-compacting concrete mixture are detected by the tester, the slump spread is required to be ≤680 mm, the air content is required to be 2% to 4%, the temperature of the self-compacting concrete into the mold is required to be controlled in 5°C to 30°C, the spread time T500 is required to be 3s to 7s, and at the same time, the test block is left on site, 2 groups are left each time (the number of tests: the slump spread and spread time T500 indexes are tested once for each truck of concrete; the air content and temperature indexes are tested at least once for each 50 m 3 of concrete). Before the concrete leaves the station, the related properties of the concrete are tested by the on-site tester, the measured slump spread is 600 mm, the air content is 3.2%, which is witnessed by the on-site supervisor and meets the related requirements and can leave the station;

[0046] Subsequently, after the concrete arrives at the site, the properties of the concrete are detected again by the on-site tester to ensure that the related properties meet the requirements. The concrete is transported to the wellhead on the ground, poured into the tank truck with an automatic stirring device through the discharge pipe arranged at the wellhead, and then transported horizontally to the pouring point by the concrete tank truck;

[0047] During pouring, the temperature, slump spread, spread time T500, air content and other properties of the self-compacting concrete mixture are detected before the concrete enters the mold, the slump spread is required to be ≤680 mm, the air content is required to be 2% to 4%, the temperature of the self-compacting concrete into the mold is required to be controlled in 5°C to 30°C, and the spread time T500 is required to be 3s to 7s. The measured slump spread is 580 mm, the air content is 3.3%, and the temperature is 16°C, which is witnessed by the on-site supervisor and meets the requirements and can be poured.

[0048] In step S4, after the grouting is completed, the C40 self-compacting concrete is initially set, and then the compacting device and the anti-side shift fixing device can be removed. When the strength of the self-compacting concrete reaches 10.0 Mpa or above, and the surface and edges thereof are not damaged due to the removal of the mold, the mold plate 3 can be removed;

[0049] Concrete curing: after the self-compacting concrete is removed from the mold, the self-compacting concrete is wrapped and cured with geotextile, and the curing time should not be less than 14 days.

[0050] In an embodiment, before the concrete is poured, the bottom foundation surface of the box culvert 2 is cleaned and moistened.

[0051] In a specific implementation, the bottom foundation surface of the box culvert 2 is cleaned and moistened by using the flushing method in the arc-shaped guide groove 23, so that the concrete poured at the bottom of the box culvert 2 adheres well.

[0052] In an embodiment, before the concrete is poured in step S3, the gap between the box culvert 2 and the front end 5 cm of the segment 1 is sealed by using an air bag in the arc-shaped guide groove 23 on the third ring box culvert 2 in each three-ring box culvert 2.

[0053] In a specific implementation, according to the design requirement, no more than three rings are poured at a time, so the gap between the third ring box culvert 2 and the front end 5 cm of the segment 1 needs to be sealed in the arc-shaped guide groove 23 on the third ring box culvert 2 before pouring. In this project, an air bag is used to seal the gap between the box culvert 2 and the segment 1, and the sealing effect is good through field test, and there is no concrete leakage during concrete pouring.

[0054] In an embodiment, the support 31 includes a first adjusting rod 311 arranged on the formwork 3, a top plate 312 arranged on the first adjusting rod 311 and vertically supported on the top surface of the inner cavity of the box culvert 2, and two second adjusting rods 313 symmetrically arranged on the top plate 312 and obliquely supported close to the first adjusting rod 311. In this way, by arranging the first adjusting rod 311 fixed by a hole and a thread on the back of the formwork 3 and the top plate 312 welded on the top of the first adjusting rod 311 and abutting against the top surface of the inner cavity of the box culvert 2, after the formwork 3 is covered and placed in the middle hole of the box culvert 2 (i.e., the arc-shaped guide groove 23 reserved on the bottom arc plate 22), the first adjusting rod 311 is rotated to move the pipe on the upper part of the first adjusting rod 311 and the top plate 312 welded on the top of the first adjusting rod 311 to the top surface of the inner cavity of the box culvert 2 for support, and then the second adjusting rods 313 on both sides of the formwork 3 are fixed by rotating the screw holes on both sides, and after adjusting and fixing the length of the second adjusting rods 313, the top parts of the second adjusting rods 313 are horizontally inserted into both sides of the top plate 312 to obliquely support the formwork 3 in the box culvert 2, which is simple to operate.

[0055] It should be noted that the first adjusting rod 311 and the second adjusting rod 313 are both composed of an outer threaded rod and an inner threaded sleeve rod.

[0056] In an embodiment, the template 3 is also provided with exhaust holes for exhausting air in the cavity during pouring and observing the concrete pouring condition. In this design, the filling and compactness of concrete can be observed through the two 5cm diameter exhaust holes (also used as observation holes) machined on the template 3. The side mold can be tapped with a wooden hammer to assist in vibrating and to help remove air bubbles in the concrete to prevent excessive vibration from causing concrete segregation. Self-compacting concrete generally does not need to be vibrated with a vibrating rod, but to prevent the gap from being too small and the self-compacting concrete from not flowing normally, a 25mm vibrating rod is provided on site to assist in construction. The theoretical volume of this time is 14.529m 3 , and the actual pouring volume is 15m 3 . During pouring, the filling of concrete can be seen through the two 5cm diameter exhaust holes (also used as observation holes) of each template 3, and the filling and compactness behind the template 3 can be judged by tapping the template 3.

[0057] In an embodiment, four core holes are drilled at the bottom of a ring of the box culvert 2 using a water drill for core sample detection.

[0058] In a specific implementation, a ring of the box culvert 2 is selected in the box culvert 2 that has been filled, and four core holes are drilled at the bottom of the structure using a water drill, as shown in Figure 2 , to observe and detect the core sample and the hole to verify the filling and compactness behind. According to the core sample results on site, it can be seen that the core sample integrity is high, and the structure shape conforms to the structure gap shape of the box culvert 2 and the pipe piece 1. The complete concrete can be seen around the core hole, which can fully prove that the box culvert 2 has been filled and compacted behind.

[0059] The track understructure filling is poured every three rings, the end of every three rings is sealed with an air bag, the middle hole is sealed with a customized template 3, the chute is used to pour along the arc surface from the side gap of the box culvert 2 during concrete pouring, and a 25mm diameter vibrating rod is provided to assist in vibrating construction.

[0060] The design volume of every three ring track understructure filling is 8.13m, and the actual filling volume on site is 9m. Each pouring takes about 2 hours, and after the mold is removed, the overall appearance effect is good, and there are no obvious holes, bubbles and other problems.

[0061] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application.

Claims

1. A construction method for segmented concrete filling of narrow spaces with circular arc sections, characterized by: The gap between the pipe segment (1) and the box culvert (2) forms a narrow space with an arc cross section. Side arc plates (21) and bottom arc plates (22) are respectively provided on both sides and the bottom of the box culvert (2). Arc guide grooves (23) are provided on both the side arc plates (21) and the bottom arc plates (22). The construction method specifically comprises the following steps: S1, preparing concrete for pouring and preparing a template (3) for closing the arc-shaped guide groove (23), wherein both ends of the template (3) are provided with side support plates for being placed on the arc-shaped guide groove (23); S2, cleaning the base surface of the arc-shaped guide groove (23), sealing the template (3) on the top surface of the arc-shaped guide groove (23) after cleaning, and erecting a bracket (31) on the top surface of the template (3) to support the inside of the box culvert (2); S3, pouring concrete from both ends of the top of the box culvert (2), the concrete entering from the narrow space of the arc section and filling the blocked arc guide groove (23) until the concrete is flush with the top of the box culvert (2); Before pouring concrete in step S3, an air bag is used in the arc guide groove (23) on the third ring box culvert (2) in each three-ring box culvert (2) to seal the 5 cm gap between the front end of the box culvert (2) and the pipe segment (1); S4, after the concrete solidifies, the bracket (31) and the formwork (3) are removed in sequence; the bracket (31) comprises a first adjusting rod (311) arranged on the formwork (3), a top plate (312) arranged on the first adjusting rod (311) and vertically supported on the top surface of the inner cavity of the box culvert (2), and two second adjusting rods (313) close to the first adjusting rod (311) and obliquely supported are symmetrically arranged on the top plate (312).

2. The method for segmented concrete filling of a narrow space with an arc section according to claim 1, characterized in that: In the step S2, before pouring concrete, the bottom foundation surface of the box culvert (2) is cleaned and moistened.

3. The method for segmented concrete filling of a narrow space with an arc section according to claim 1 is characterized by: The template (3) is also provided with an exhaust hole for discharging air in the cavity during pouring and for observing the concrete pouring condition.

4. The method for segmented concrete filling of a narrow space with an arc section according to claim 1 is characterized by: A core is taken from the bottom of a ring of the box culvert (2) using a water drill, and a total of 4 core holes are used for core sample testing.

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