JPH0241625B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a sliding form construction method in which concrete or reinforced concrete structures are constructed by continuously pouring concrete while gradually moving a sliding form upward. , relates to a demolding strength management method for moving the formwork so that it is demolded only when the concrete poured into the sliding formwork reaches an appropriate strength.

The above-mentioned sliding construction method can be said to be a construction method with higher construction efficiency than the known method of pouring concrete into a stationary form and then disassembling the stationary form after the concrete has hardened. In this case, it is required that the concrete in the area where the formwork is moved and demolded has reached an appropriate strength.

In other words, when the concrete develops strength faster than expected, the slip resistance between the sliding formwork and the concrete increases, and sometimes the concrete wall rises together, causing cracks or even serious defects such as the inability to slip. This may cause a gap.

On the other hand, if the sliding formwork loses its movement too early, it will be removed from the form when the concrete is uncured and not strong enough to stand on its own, causing sagging or flaking of the concrete. It also becomes.

[Conventional technology]

Conventionally, when implementing the above-mentioned sliding form construction method, the strength development state of the demolded concrete wall surface was always artificially inspected one by one while the formwork was moving, and the moving speed was adjusted to suit the concrete condition based on the inspection results. I am trying to operate it so that

However, when using the above-mentioned conventional means, it is practically difficult for workers to accurately grasp the state of strength development of concrete walls throughout the entire process, and therefore it is natural that they are always properly and efficiently maintained. can't get good results,
The issue here was how to manage the automatic movement speed of the formwork.

[Problem that the invention seeks to solve]

Therefore, the present invention aims to improve the strength of concrete at a young age, which is generally affected by temperature, humidity, and slump (softness).
This was done by focusing on the fact that the influence of temperature is the most significant.

That is, there is a relationship as shown in FIG. 1 between concrete temperature (integrated temperature) and compressive strength.

Here, the integrated temperature is calculated from the following general formula.

M: Cumulative temperature T: Concrete temperature (℃) △t: Time when concrete temperature is T (hr) r: Constant (T>20℃: r=5, T≦20℃: r=
2), M=Σ{T+|T-20|/r}×△t In other words, as shown in Figure 1, for some concrete, the relationship between the two can be expressed by several straight lines regardless of the temperature history. It can be approximated by

Therefore, by actually measuring the concrete temperature of the actual structure and calculating the cumulative temperature after pouring, it is possible to estimate the compressive strength of demolded concrete at any time from the same figure.

Based on the above principle, the cumulative temperature of the concrete at the demolding position is calculated, the demolding strength is estimated from the relationship between the compressive strength and the cumulative temperature shown in Figure 1, and the moving speed of the sliding formwork is controlled based on this. The purpose of this is to ensure that the construction of concrete structures using the sliding form construction method is always appropriate and efficient.

[Means for solving problems]

The present invention uses a sliding form construction method in which a temperature measuring device is installed in the sliding formwork, and the temperature of the concrete poured in the formwork is measured using this device, and the cumulative temperature after the concrete is poured is calculated. Then, the demolding strength of the concrete is estimated from the known relationship between the cumulative temperature and the compressive strength, and the moving speed of the sliding formwork is controlled based on the result. Its purpose is to try to solve problems.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. As shown in FIG. 2, both the inner and outer sliding formwork 1,
In order to measure the temperature of the concrete 3 poured into the concrete 2, a plurality of temperature measuring elements 4,
4'..., 5, 5'... are mounted on both sides respectively, and each temperature measuring element 4, 4'..., 5, 5'...
are electrically connected to a computer 7 such as a microcomputer of the control system 6 shown in FIG.

Here, the above-mentioned inner and outer sliding formworks 1 and 2 are fixed to a substantially gate-shaped yoke 9 via wallers 8, similar to those used in the conventional sliding form construction method, and the yoke 9 is , by the operation of a hydraulic jack 11 which is installed vertically in both the inner and outer sliding formworks 1 and 2 and which takes a reaction force on the support rod 10 that is buried in the poured concrete.
By being pulled upward, both the inner and outer sliding formworks 1 and 2 can be pulled up and moved.

Moreover, the temperature measuring elements 4, 4'..., 5, 5'...
As for..., a silicon temp element or the like may be used.

Thus, the temperature of the concrete 3 during actual movement of the sliding forms 1 and 2 can be measured by the temperature measuring elements 4, 4'..., 5, 5'....

At the same time, the formwork height H from the base end to the top end of the sliding formworks 1 and 2 and the concrete placement time of each layer are input into the computer 7 at any time, and the control system 6 shown in FIG. The cumulative temperature M of the concrete 3 at the demolding position is calculated, and the demolding strength is estimated from the relationship between the compressive strength σKgf/cm ² and the cumulative temperature M shown in FIG.

Here, as an example of calculating the cumulative temperature, the temperature measuring elements 4, 4'..., 5, 5'...
As shown in the figure, a case will be explained in which three molds are installed in each of the inner and outer sliding formworks 1 and 2.

As shown in Fig. 4, the cumulative temperature M of the top layer of concrete 3a poured at a certain time _t0
The calculation is as follows.

Since the height H of the formwork and the temperature of the concrete 3a at any time t are constantly measured, the time required to pass the distance H/3 of the height H of the formwork is:
They are as follows.

Time required to pass a distance of H/3 at the top of the formwork t ₁ = tH/3 - t ₀ Time required to pass a distance of H/3 at the center of the formwork t ₂ = t2H/3 - tH/3 The time required to pass the distance of H/3 at the bottom of the formwork t ₃ = t 3 H / 3 - t 2 H / 3 Also, the average temperature of the concrete 3 during this time T ^m _i is T ^m _i = ∫Ti (t)・dt/ti (i=1, 2, 3) Here, t2H/3 is the time when the point iH/3 from the top of the formwork passes through the target concrete layer. ti is the time when the point iH/3 from the top of the formwork passes through the target concrete layer. i-th formwork height from the end H/3
The time required to pass the distance Ti(t) is the distance i from the top of the formwork at time t.
The reading of the second temperature measuring device (take the average value of the temperature measuring elements of the inner formwork and the outer formwork) Therefore, the integrated temperature M is as follows.

M=Σ{T+|T-20|/r}・△t= ₃ 〓 ^t-1 {T ^m _i +|T ^m / _i −20|/r}・ti This integrated temperature is shown in Figure 1. The compressive strength is determined by substituting the relationship between the compressive strength and the integrated temperature into an approximate formula.

In this way, the control system 6 constantly displays the concrete strength at the demolding position on the printer 7', and based on this strength, the formwork 1,
The moving speed of 2 can be controlled arbitrarily.

In addition, concrete temperature measuring elements 4, 4'...,
The more positions 5, 5', .

〔Effect of the invention〕

Since the method of the present invention can be implemented as explained above, the formworks 1 and 2 are By measuring the concrete temperature using the set temperature measuring elements 4, 4'..., 5, 5'... and calculating the cumulative temperature after pouring, the demolding strength can be easily estimated. Based on the results sliding formwork 1,
By controlling the movement speed in step 2, when constructing concrete structures using the sliding form construction method, it is possible to prevent cracks from occurring in the concrete wall when moving the formwork, or causing concrete to sag or fall off. This makes it possible to always carry out appropriate and efficient construction methods.Also, by measuring the concrete temperature with the temperature measuring elements 4, 4'..., 5, 5'... of the sliding formworks 1, 2. At the same time, by inputting the formwork height H and concrete placement time of each layer into the computer at any time, it is possible to easily calculate the cumulative temperature of the concrete at the demolding position and estimate the compressive strength of the demolded concrete. Therefore, the demolding strength can be estimated instantaneously from the relationship between the compressive strength and the integrated temperature, and since commercially available products can be used for each measurement and calculation device, it is possible to implement the method at low cost.

[Brief explanation of drawings]

The attached drawings show an example of the concrete demolding strength control method in the sliding form construction method according to the present invention, and Figure 1 shows the relationship between concrete compressive strength and cumulative temperature, which is the basis of the control method. 2 is a longitudinal cross-sectional side view of a sliding formwork in which a temperature measuring element is set, FIG. 3 is an overall schematic diagram of a control system used in the same method, and FIG. 4 is an explanatory diagram of cumulative temperature calculation. 1, 2... Sliding formwork, 3... Pouring concrete, 4, 4', 5, 5'... Temperature measuring element, M...
Cumulative temperature, σKgf/cm ² ... Compressive strength.

Claims (1)

[Claims] 1 In the sliding form construction method, a temperature measuring element is attached to the sliding formwork, and by measuring the temperature of the concrete poured in the formwork, the cumulative temperature after the concrete is poured is calculated, and the temperature of the concrete is measured. Demolding concrete in a sliding form construction method, characterized in that the demolding strength of concrete is estimated from the relationship between cumulative temperature and compressive strength, and the moving speed of the sliding formwork is controlled based on the estimation result. Strength management method.