Concrete formwork with water cooling and anti-cracking effects

Abstract

The utility model discloses a concrete formwork with water cooling and anti-cracking effects. The concrete formwork comprises a formwork body, a supporting rod and a box body fixed to the inner wall of the formwork body. A plurality of transverse rib plates are fixed in the box body at intervals in a staggered manner; the transverse rib plates which are fixed in a staggered manner at intervals form a snake-shaped water passing channel in the box body; a water inlet is formed in the upper portion of the box body, and a water outlet is formed in the lower portion of the box body. When the concrete is poured, cooling water with certain water temperature and pressure is injected into the box body along with the pouring of the concrete, and the cooling water flows along the snake-shaped water passing channel to take away heat generated by the hydration reaction of the concrete. According to the utility model, the problem that the cooling and anti-cracking effects are not ideal due to the fact that surface water flowing or spraying cooling cannot be carried out when the internal temperature of the lining concrete reaches the highest before the template of the traditional lining concrete is removed is solved. The device has the advantages of being timely in cooling, high in speed and remarkable in cooling and anti-cracking effect.

Description

Technical Field

[0001] The utility model relates to a template for pouring concrete components, in particular to a concrete template with water cooling and crack prevention functions. The utility model belongs to the technical field of concrete temperature control and crack prevention. Background Art

[0002] As a supporting facility of each hydropower station / power station, the inner wall of the water tunnel is cast with a layer of concrete lining. The main function of the concrete lining is to reinforce the inner wall of the tunnel and prevent the infiltration of internal water and external water. Therefore, the concrete lining after forming must not only be strong, but also must not have large cracks. However, due to the characteristics of high grade, high heat generation and fast heating of the lining concrete, its internal temperature is difficult to control. In addition, its special thin-walled structure makes it extremely difficult to prevent and control cracks in the concrete lining, and cracking is the norm.

[0003] In order to control the occurrence of cracks in concrete linings and avoid them as much as possible, the commonly used technical means are: 1. Control the temperature and time of concrete pouring; 2. Cool the poured lining concrete with water by burying water pipes inside the concrete to cool it down and take away some of the heat; 3. Maintain the poured lining concrete by running water or spraying it on the surface of the lining concrete after the formwork is removed. However, it has been proven that traditional temperature control measures and crack prevention measures are not ideal, and some projects still have serious cracking phenomena, which seriously affects the quality of the project entity. Utility Model Content

[0004] In view of the above reasons, the purpose of the utility model is to provide a concrete formwork with water cooling and crack prevention effects. The concrete formwork is accompanied by the concrete pouring process, timely takes away the hydration reaction heat generated by the concrete, and plays the role of cooling and crack prevention.

[0005] To achieve the above purpose, the utility model adopts the following technical scheme: a concrete formwork with water cooling and crack prevention effects, which includes a formwork body and a support rod for supporting the formwork body; a box body is fixed on the inner wall of the formwork body, and a plurality of transverse ribs are fixed in the box body at intervals and offsets;

[0006] The transverse ribs fixed at intervals and offsets form a serpentine water passage in the box body; a water inlet connected to the water inlet pipe is opened at the upper part of the box body, and a water outlet connected to the water return pipe is opened at the lower part of the box body;

[0007] The length and width of the box body are consistent with the length and width of the template body;

[0008] The length of the transverse ribs fixed in the box body is less than the length of the box body, and the width is equal to the thickness of the inner cavity of the box body.

[0009] Preferably, a plurality of steel pillars are fixed in the box.

[0010] Preferably, the steel support is located at a gap between an end of the transverse rib and an adjacent transverse rib.

[0011] Preferably, the box body is made of steel plate or iron plate or other metal plate with good thermal conductivity; the transverse ribs fixed in the box body are metal plates or PVC plates or plastic steel plates.

[0012] Since the utility model has a box fixed on the inner wall of the formwork body, and a serpentine water passage is provided in the box, cooling water is passed through the box during the concrete pouring process, and the box surface is in full contact with the concrete, so as to timely take away the heat generated by the hydration reaction of the concrete, especially before the highest temperature of the concrete appears, the temperature inside the concrete can be timely and quickly reduced, thereby solving the problem that the current lining concrete cannot be cooled by surface water flow or spraying before the formwork is removed and when the temperature inside the lining concrete is the highest, resulting in unsatisfactory cooling and crack prevention effects. The utility model has the characteristics of timely cooling, fast speed and good effect, not only the heat dissipation effect of the concrete surface is obvious, but also the control effect of the highest temperature inside the concrete is better; and the crack prevention effect is significant. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A schematic diagram of a concrete formwork structure for a conventional concrete casting attachment;

[0014] Figure 2 This is a schematic diagram of the concrete formwork structure of the utility model which has the functions of cooling by water and preventing cracking;

[0015] Figure 3 This is a schematic diagram of the decomposition structure of the concrete formwork of the utility model;

[0016] Figure 4 It is a schematic diagram of the internal structure of the utility model. DETAILED DESCRIPTION

[0017] The structure and features of the utility model are described in detail below in conjunction with the accompanying drawings and embodiments. It should be noted that various modifications can be made to the embodiments disclosed herein, and therefore, the embodiments disclosed in the specification should not be regarded as limitations on the utility model, but are merely examples of embodiments, the purpose of which is to make the features of the utility model obvious.

[0018] The inventors have found through research that the highest temperature of the lining concrete occurs before the casting formwork is removed, while the traditional surface heat dissipation and cooling measures can only be carried out after the formwork is removed, and the lining concrete surface can be cooled by running water or spraying. At this time, on the one hand, the cooling timing is delayed and the moment when the highest temperature of the lining concrete occurs has been missed. On the other hand, the running water / spraying on the surface of the lining concrete has a significant cooling and heat dissipation effect on its surface, but the temperature control effect on its interior is not obvious, which leads to the unsatisfactory cooling effect of the traditional lining concrete and the widespread cracking phenomenon.

[0019] Therefore, the applicant of the utility model makes full use of the fact that the contact area between the concrete pouring formwork and the concrete is the largest and the contact time is the longest during the concrete pouring, and redesigns the concrete formwork structure. During the concrete pouring, along with the change of the concrete temperature history, especially before the highest temperature of the concrete appears, the concrete is cooled by the concrete formwork to achieve the purpose of pouring, cooling and crack prevention.

[0020] Figure 1 The figure is a schematic diagram of a traditional formwork structure for pouring concrete lining. As shown in the figure, the traditional concrete formwork includes a formwork body 1 and a support rod 2; one end of the support rod 2 is welded to the formwork body 1, and the other end is fixed to the ground to support the formwork body 1. When in use, several formwork bodies 1 are connected to each other through connectors and arranged close to the inner wall of the tunnel; after the connected formwork bodies are fixed, concrete is poured between the formwork and the inner wall of the tunnel to form a concrete lining layer.

[0021] like Figure 2-Figure 4 As shown, the utility model has a box body 3 fixed on the inner wall of the template body 1 by welding, and a plurality of transverse ribs 4 are fixed in the box body at intervals and offsets, and the transverse ribs 4 fixed at intervals and offsets form a serpentine water passage 5 in the box body. A water inlet 6 connected to the water inlet pipe is opened at the upper part of the box body, and a water outlet 7 connected to the return pipe is opened at the lower part of the box body.

[0022] While pouring concrete, cooling water with a certain water temperature and pressure is introduced into the box body 3. The cooling water flows in from the water inlet and flows out from the water outlet along the serpentine water passage. The heat generated by the hydration reaction of the concrete is taken away during the water flow, thereby achieving the purpose of cooling and crack prevention.

[0023] Figure 2-Figure 4The schematic diagram of the structure of the preferred embodiment of the concrete formwork with water cooling and crack prevention functions of the utility model. As shown in the figure, in this embodiment, the length L and width H of the box body 3 are consistent with the length and width of the formwork body 1, and the box body 3 can be made of steel plate, iron plate or other metal plate with thermal conductivity. The transverse ribs 4 fixed in the box body can be metal plates or PVC plates or plastic steel plates, and their length is less than the length L of the box body, and the width is equal to the thickness d of the inner cavity of the box body. The transverse ribs are fixed in the box body at intervals and offsets, so that a serpentine water passage is formed in the box body.

[0024] Since the water injected into the box body 3 has a certain pressure and temperature, and before the formwork body 1 is removed, the poured concrete also exerts a certain force on the box body 3, in order to prevent the box body from deforming, the transverse ribs fixed in the box body also have a certain supporting effect on the box body, so that the box body has a certain bearing capacity and stability. At the same time, Figure 4 As shown, the utility model further has at least one steel support 8 welded at the gap between each transverse rib and its adjacent transverse rib, which plays a role of further reinforcement.

[0025] As concrete is poured, it deforms and imposes external loads on the formwork body 1 and the box body 3. In order to cool down, the water in the box body exerts pressure on the formwork body and the transverse ribs in the box body. Therefore, there are requirements for the thickness d of the box body 3 and the spacing S between two adjacent transverse ribs in the box body.

[0026] First, considering the external load of poured concrete on the formwork, the two adjacent transverse ribs are simplified into a one-span continuous beam. The mid-span deflection is calculated by the poured concrete load borne by the concrete formwork to meet the relevant requirements of formwork deformation, and the value of the distance S between the two adjacent transverse ribs is obtained. 1 :

[0027]

[0028] Where: E is the elastic modulus of the steel used for the box, I is the section inertia moment of the steel used for the box, which can be obtained by referring to the "Steel Structure Design Code"; q 1 It is the external equivalent uniformly distributed load borne by the box body, which can be obtained by referring to the "Specifications for Construction of Hydraulic Concrete" and converting it according to the external loads such as the newly poured concrete borne by the box body.

[0029] The external deformation of the box can be obtained by simplifying the two adjacent transverse ribs into a one-span continuous beam, and calculating its mid-span deflection according to the external loads such as the poured concrete borne by the box, so that it meets the control standard of the formwork deformation. The control standard can be obtained by referring to the "Specifications for Construction of Hydraulic Concrete" and is generally taken as 1 / 400 of the calculated span of the formwork component.

[0030] Secondly, it is also necessary to consider the internal load caused by water flowing through the concrete formwork, that is, the water flowing through the box body, and obtain the value S of the distance between two adjacent transverse ribs. 2 :

[0031]

[0032] Where: q 2 is the internal equivalent uniformly distributed load borne by the box, which can be equivalently converted according to the internal loads such as the water pressure P borne by the box panel; E is the elastic modulus of the steel used in the box, which can be obtained by referring to the "Steel Structure Design Code"; t is the thickness of the steel used in the box;

[0033] α is a calculation coefficient, which is determined by the ratio of the long side to the short side of the box panel between two adjacent transverse ribs. Usually, its value range is 0.03-0.05.

[0034] The internal deformation of the box can be obtained by simplifying the panel between two adjacent transverse ribs into a rectangular thin plate with four sides fixed under uniform load, and calculating its central deflection according to the internal loads such as the water pressure borne by the box, so that it meets the formwork deformation control standard. The control standard can be obtained by referring to the "Specifications for Construction of Hydraulic Concrete" and is generally taken as 1 / 400 of the calculated span of the formwork component.

[0035] Combining formula (1) and formula (2), the distance s between two adjacent transverse ribs can be finally determined as:

[0036] s=min{s 1 ,s 2 ) (3).

[0037] After considering the spacing of the transverse ribs in the box, the thickness d of the box also needs to be considered.

[0038] According to the basic principles of hydraulics, the energy equation of water flow in the box is as follows:

[0039]

[0040] Where: h is the water head at the water inlet of the box, h 0 is the water head at the water outlet of the box; P is the water inlet pressure, P 0 is the outlet pressure, which is generally atmospheric pressure; s is the distance between two adjacent transverse ribs; v is the flow rate of water; ρ is the density of water; g is the local gravitational acceleration; λ is the along-the-way resistance coefficient, ζ is the local resistance coefficient, which can be obtained by referring to the "Hydraulic Design Manual"; l is the along-the-way distance of the serpentine water passage in the box, which can be calculated by l=HL / s, where L is the length of the box; H is the height of the box; R is the hydraulic radius, which can be calculated by R=sd / (2s+2d).

[0041] By deriving the water flow energy equation from formula (4), we obtain the following cubic equation about d:

[0042] d 3 +kd+m=0 (5)

[0043] in:

[0044]

[0045]

[0046] Δ k is the water head difference between the inlet and outlet of the box, which can be calculated by Δ h =hh 0 =(Hs)sinθ, where θ is the angle between the template and the horizontal plane when it is installed; Δ p is the water pressure difference between the inlet and outlet of the box, which can be measured by Δ P =PP 0 To obtain.

[0047] Solving formula (5) can obtain the thickness d of the box.

[0048] The utility model has an ingenious structural design and has good water-passing, cooling and crack-preventing effects.

[0049] Finally, it should be noted that the above-described embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the utility model.

Claims

1. A concrete formwork with water cooling and crack prevention effects, comprising a formwork body and a support rod for supporting the formwork body, characterized in that: A box is fixed on the inner wall of the template body, and a plurality of transverse ribs are fixed in the box at intervals and in a staggered manner; The transverse ribs fixed at intervals and offsets form a serpentine water passage in the box body; a water inlet connected to the water inlet pipe is opened at the upper part of the box body, and a water outlet connected to the water return pipe is opened at the lower part of the box body; The length and width of the box body are consistent with the length and width of the template body; The length of the transverse ribs fixed in the box body is less than the length of the box body, and the width is equal to the thickness of the inner cavity of the box body.

2. The concrete formwork with water cooling and crack prevention functions according to claim 1 is characterized in that: A plurality of steel pillars are also fixed in the box.

3. The concrete formwork with water cooling and crack prevention functions according to claim 2 is characterized in that: The steel support column is located at a gap between the end of the transverse rib and the adjacent transverse rib.

4. The concrete formwork with water cooling and crack prevention functions according to claim 3 is characterized in that: The box body is made of steel plate, iron plate or other metal plate with heat conductivity; The transverse ribs fixed in the box body are metal plates, PVC plates or plastic steel plates.

Images