WO2020045117A1

WO2020045117A1 - Hat-shaped steel sheet pile and method for producing steel sheet pile wall

Info

Publication number: WO2020045117A1
Application number: PCT/JP2019/032113
Authority: WO
Inventors: 俊介森安; 典佳原田; 裕章中山; 正和武野; 妙中　真治
Original assignee: 日本製鉄株式会社
Priority date: 2018-08-31
Filing date: 2019-08-16
Publication date: 2020-03-05
Also published as: JP7143890B2; JP2022120069A; JPWO2020045117A1

Abstract

This hat-shaped steel sheet pile is provided with: a web extending along the width direction on a first side in the thickness direction in a cross section orthogonal to the lengthwise direction; a pair of flanges extending on both sides in the width direction from both ends of the web in the width direction and toward a second side in the thickness direction; a pair of arms extending along the width direction from the ends of each of the pair of flanges on the second side in the thickness direction and toward both sides in the width direction; and a pair of fitting joints formed on the end sections of each of the pair of arms on the opposite side from each of the pair of flanges. The hat-shaped steel sheet pile has an effective width W of 105 cm or more, and the total length B_TTL (cm) of the web, the pair of flanges, and the pair of arms in the cross section and the weight wt (N/cm²) of the hat-shaped steel sheet pile per unit area in a side surface parallel to the lengthwise direction satisfy formula (i) indicated below.

Description

Hat-shaped steel sheet pile and method of manufacturing steel sheet pile wall

The present invention relates to a hat-shaped steel sheet pile and a method for manufacturing a steel sheet pile wall.

形 Hat-shaped steel sheet piles are widely used in civil engineering and construction work to construct walls for earth retaining and waterproofing. Various techniques for improving the workability and cross-sectional performance of hat-shaped steel sheet piles have been proposed so far. For example, in Patent Document 1, the section performance is defined by defining the relation between the unit weight per 1 m of the wall width of the steel sheet pile wall and the second moment of area, and the relation between the effective width and the flange width of the hat-shaped steel sheet pile. There is described a technique for providing a hat-shaped steel sheet pile having a small unit weight and excellent economic efficiency while securing the same.

Japanese Patent No. 3458109

On the other hand, as shown in FIG. 5A and FIG. 5B, when the hat-shaped steel sheet pile is driven by the vibro-hammer method, the hat-shaped steel sheet pile may flap. As shown in FIG. 5A, vibro-hammer method is a method for pouring while applying longitudinal vibration V _V of Da設traveling direction (z direction in the drawing) to the hat-shaped steel sheet pile 1 with the vibro-hammer 6. In such a vibro-hammer method, prior to restriction by the fitting of the joint between the pouring has been hat-type steel sheet pile 1P, soil resistance, and the direction of the longitudinal vibration V _V applied from vibro-hammer 6 slightly from pouring the traveling direction the influence of the shift, the membrane vibration V _M is generated in the thickness direction of the hat-shaped steel sheet pile 1. As shown schematically in Figure 5B, which membrane vibration V _M is amplified to the extent visible is called the flutter of the hat-shaped steel sheet pile 1.

If fluttering of the hat-shaped steel sheet pile 1 described above occurs, prior to the fitting portion of the joint of the pouring the hat-shaped steel sheet pile 1P, the thickness direction by the membrane vibration V _M (y direction in the drawing) The joint of the hat-shaped steel sheet pile 1 that vibrates rapidly is hit against the joint of the hat-shaped steel sheet pile 1P that does not vibrate, which may increase the noise or damage the joint. Moreover, film vibration V _M of the hat-shaped steel sheet pile 1 impair the linearity of the pouring traveling direction of the hat-shaped steel sheet pile 1 (z direction in the drawing), in some cases it leads to deterioration of the construction quality. Therefore, it is desirable to reduce flapping in the construction of the hat-shaped steel sheet pile 1, but a method for that purpose is not shown in the prior art as in Patent Document 1.

Therefore, an object of the present invention is to provide a new and improved hat-shaped steel sheet pile and a method for manufacturing a steel sheet pile wall, which can effectively reduce flapping generated when the hat-shaped steel sheet pile is driven. And

According to an aspect of the present invention, a hat-shaped steel sheet pile includes, in a cross section orthogonal to a longitudinal direction, a web extending along a width direction on a first side in a thickness direction, and a width extending from both ends in a width direction of the web. A pair of flanges extending on both sides in the thickness direction and toward the second side in the thickness direction, and along the width direction from the respective ends of the pair of flanges on the second side in the thickness direction and in the width direction. And a pair of mating joints formed at the ends of the pair of arms opposite the pair of flanges, respectively, and having an effective width W of 105 cm. And the total length B _TTL (cm) of the web, the pair of flanges, and the pair of arms in cross section, and the weight wt of the hat-shaped steel sheet pile per unit area on the side surface parallel to the longitudinal direction (N / cm ² ) and the relationship of the following equation (i) Fulfill.

In the above-mentioned hat-shaped steel sheet pile, the effective width W may be 120 cm or more, and the total length B _TTL and the weight wt may satisfy the relationship of the following formula (ii).

According to another aspect of the present invention, there is provided a method for manufacturing a steel sheet pile wall using the above hat-shaped steel sheet pile. The method of manufacturing a steel sheet pile wall may include a step of driving the hat-shaped steel sheet pile into the ground while applying longitudinal vibration in the driving direction of the hat-shaped steel sheet pile using a vibratory hammer.

According to the above configuration, it is possible to effectively reduce the fluttering that occurs when the hat-shaped steel sheet pile is driven.

It is sectional drawing of the hat-shaped steel sheet pile which concerns on one Embodiment of this invention. It is a figure for demonstrating the fitting center of the hat-shaped steel sheet pile shown in FIG. 5 is a graph showing the effective width on the vertical axis and the index on the frequency of the membrane vibration on the horizontal axis for Comparative Examples and Examples. It is a graph which shows the frequency weighting characteristic of noise. It is a figure for explaining fluttering which occurs at the time of driving of a hat-shaped steel sheet pile. It is a figure for explaining fluttering which occurs at the time of driving of a hat-shaped steel sheet pile.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the specification and the drawings, components having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted.

FIG. 1 is a sectional view of a hat-shaped steel sheet pile according to one embodiment of the present invention. As shown in FIG. 1, a hat-shaped steel sheet pile 1 has a width on a first side in a thickness direction (a depth side in a y direction in the figure) in a cross section orthogonal to a longitudinal direction (z direction in the figure). Web 2 extending in the direction (x direction in the figure), and from both ends in the width direction of the web 2 to both sides in the width direction and to the second side in the thickness direction (front side in the y direction in the figure) Flanges 3A, 3B extending toward the width direction and forming a flange angle θ (the acute angle side) with the width direction, and from the respective ends of the flanges 3A, 3B on the second side in the thickness direction, along the width direction.

Arms

4A and 4B extending toward both sides in the width direction, and

fitting joints

5A and 5B formed at ends of

arms

4A and 4B opposite to flanges 3A and 3B, respectively.

FIG. 1 shows the dimensions of each part of the hat-shaped steel sheet pile 1, specifically, the length Bw and the thickness tw of the web 2, the length Bf of the flanges 3A and 3B, and the

arms

4A and 4B. Is shown as the length Ba. Here, the length Bw is a distance between two intersections formed between the thickness center line of the web 2 and the respective thickness center lines of the flanges 3A and 3B. Similarly, the length Bf is the distance between two intersections formed between the thickness center line of the flange 3A and the respective thickness center lines of the web 2 and the arm 4A. The length Ba is the distance between the intersections formed between the thickness center line of the thickness center line and the flange 3A of the arms 4A, a fitting center E _A fitting joint 5A. Since the cross-sectional shape of the hat-shaped steel sheet pile 1 is symmetrical about the neutral axis in the width direction (the y-axis in the figure), the flange 3B has the same length Bf as the flange 3A, and the arm 4B has the arm 4A. The length is Ba as in the case of

Further, FIG. 1 shows an effective width W and a total length B _TTL of the hat-shaped steel sheet pile 1. Here, the effective width W is the distance between the mating fitting 5A, each of the mating centers _E A of 5B, _{E B.} The total length _{B TTL,} the web 2, the flange 3A of the illustrated cross-section, 3B, and the arms 4A, a total length of 4B, length Bw, _B using a length Bf, and length Ba _TTL = Bw + 2Bf + 2Ba. As described below, in the hat-shaped steel sheet pile 1 according to the present embodiment, the effective width W is 105 cm or more, and the hat-shaped steel sheet pile per unit area on a side surface parallel to the total length B _TTL and the longitudinal direction. 1 satisfies a predetermined relationship.

When the shape of the hat-shaped steel sheet pile 1 shown in FIG. 1 is geometrically established, the effective width W, the web length Bw, the sectional height H, and the flange angle θ are W−Bw−2H / tan θ> 0 is satisfied. Here, the sectional height H is the sectional height of the hat-shaped steel sheet pile 1 including the thickness of the web 2 and the

arms

4A and 4B and not including the protrusions of the

fitting joints

5A and 5B.

FIG. 2 is a view for explaining a fitting center of the hat-shaped steel sheet pile shown in FIG. 1. As shown in the figure, the fitting joint 5B of another hat-shaped steel sheet pile 1 that is driven adjacent to the fitting joint 5B of the hat-shaped steel sheet pile 1 is fitted. Fitting center E _A fitting joint 5A, when placing the arms 4B and the fitting joint 5B another hat-shaped steel sheet pile 1 virtually, end position of the arm 4A of the fitting joint 5A is formed And a point on the designed thickness center line of the arm 4A and the arm 4B, which is located between the end position of the arm 4B where the virtual fitting joint 5B is formed. Fitting the center of the fitting joint 5B located on the opposite side of the hat-shaped steel sheet pile 1 E _B can also be defined similarly.

The results examined by the present inventors in order to effectively reduce the flapping occurring at the time of driving in the hat-shaped steel sheet pile according to the embodiment of the present invention will be described below. First, in order to reduce the flapping, it is desirable to lower frequency the membrane vibration occurs in the thickness direction of the hat-shaped steel sheet pile 1 V _{M (see} FIGS. 5A and 5B). It is empirically known that fluttering occurs in the early stage of casting and gradually stops as the casting proceeds, but this is because the distance from the top end of the hat-shaped steel sheet pile 1 to the ground surface is reduced. It is considered that this is the longest in the initial stage, and gradually becomes shorter as the casting proceeds. Displacement in the thickness direction of the hat-shaped steel sheet pile 1 is restrained by a joint between the top end of the hat-shaped steel sheet pile 1 gripped by the vibratory hammer 6, the ground, and another hat-shaped steel sheet pile 1P previously driven. The portion near the ground surface is a fixed point of vibration in the thickness direction of the hat-shaped steel sheet pile 1. Accordingly, the distance between the fixed point is the longest of the pouring initially low natural frequency of the hat-shaped steel sheet pile 1, the hat-shaped steel sheet pile 1 at this stage resonance membrane vibrating V _M, less number of vibration and therefore a large vibration is generated in the amplitude, membrane vibration V _M will be amplified. In other words, lower if membrane vibration V _M than the natural frequency of the vibration frequency hat-shaped steel sheet pile 1 of the membrane vibration V _M at the beginning of pouring is not amplified. Since the pouring of the hat-shaped steel sheet pile 1 is the natural frequency the shorter distance between the fixed point is higher by progress in early pouring membrane vibration V _M frequency of hat-type steel sheet pile 1 of is lower than the natural frequency, the amplification of the membrane vibration V _M even pouring progresses, i.e. flapping hat-shaped steel sheet pile 1 does not occur.

The frequency f _mn of the membrane vibration in the rectangular plate having the side lengths a and b is calculated using the number of modes m and n, the gravitational acceleration g, the weight wt of the plate per unit area, and the in-plane tension S as follows. It can be expressed as in equation (1). From equation (1), it can be seen that the larger the weight wt and the longer the side lengths a and b, the smaller the frequency _fmn , that is, the lower the frequency of the film vibration.

Here, the low frequency of than the membrane vibration example conventional hat-shaped steel sheet pile, i.e. the frequency of the membrane vibration of the conventional hat-shaped steel sheet pile the frequency of the membrane vibration of the hat-shaped steel sheet pile 1 f _{_mn 'f mn} Consider the condition for making it smaller. In the basic mode (m = n = 1), when the weight w and the side length a are different and other conditions are common, the ratio f ′ / f of the frequency of the membrane vibration to the conventional hat-shaped steel sheet pile is: It can be expressed as the following equation (2). The higher mode (m> 1 or n> 1) does not need to be considered as a cause of the fluttering of the hat-shaped steel sheet pile 1 because the amplitude becomes smaller.

Further, when a rectangular plate having the side lengths a and b is applied to the shape of the hat-shaped steel sheet pile, the side length b in the longitudinal direction of the hat-shaped steel sheet pile is sufficiently longer than the side length a in the cross-sectional direction (for casting). (In the initial stage, the side length b is 10 times or more the side length a.) Therefore, the terms (a ′ / b) ² and (a / b) ^{2 in} the equation (2) can be ignored because they are sufficiently small. As a result, the frequency ratio f ′ / f can be expressed as the following equation (3).

According to the above equation (3), in order to reduce the ratio f ′ / f of the frequency of the membrane vibration of the hat-shaped steel sheet pile 1 to the conventional hat-shaped steel sheet pile, the side in the cross-sectional direction of the hat-shaped steel sheet pile is required. The length a, that is, the total length B _TTL shown in FIG. 1 is increased, or the weight wt of the hat-shaped steel sheet pile 1 per unit area on the side surface parallel to the longitudinal direction (the web 2, the flanges 3A, 3B, And the average value of the

arms

4A and 4B). That is, for K (an index relating to the membrane vibration of the hat-shaped steel sheet pile 1) defined as the following equation (4), if K in the hat-shaped steel sheet pile 1 is smaller than K in the conventional hat-shaped steel sheet pile, Membrane vibration is reduced. First, the total length B _TTL can be increased by increasing the effective width W of the hat-shaped steel sheet pile 1. The expansion of the effective width W is economical because the number of the hat-shaped steel sheet piles 1 constituting the steel sheet pile wall having the same wall width is reduced, so that the effective width W is set to 105 cm or more below. The appropriate total length B _TTL and weight wt were considered.

Table 1 shows cross-sectional specifications of a conventional hat-shaped steel sheet pile (Comparative Examples 1 to 3) and a hat-shaped steel sheet pile (Examples 1 to 9) according to the embodiment of the present invention. In Table 1, W is the effective width (cm), I is the second moment of area per cm of the steel sheet pile wall (cm ⁴ / m), B _TTL is the total length (cm), and wt (N / cm ^2). ) Is the weight per unit area on the side surface parallel to the longitudinal direction, and K (N ^-1/2 ) is an index calculated by the above equation (4). Moreover, the frequency ratio r _f in Table 1, as film frequency ratio of vibration between the conventional hat-shaped steel sheet pile having respective embodiments and equivalent moment of inertia of I, the above equation (3 ) _Is calculated by substituting the total length B _TTL into the side length a.

FIG. 3 shows the effective width W (cm) on the vertical axis and the K (N ^-1/2 ) shown in Table 1 on the horizontal axis for Comparative Examples 1 to 3 and Examples 1 to 9 described above. FIG. Referring to the graph of FIG. 3, in Examples 1 to 9, the effective width W is equal to or greater than 105 cm and the index K calculated by the equation (4) is included in the area of 0.030N- ^{1 / 2} or less. Have been. The hat-shaped steel sheet pile of Examples 1 to 9, both well below the 1 frequency ratio r _f, the membrane vibration than Comparative Examples 1 to 3 are low-frequency reduction. Moreover, the frequency ratio r _f is less than 0.9, Comparative Examples 1 to 3 Example 2 membrane vibration is significantly lower frequency of than, Example 3, Example 5, Example 6 In Examples 8, 9 and 9, the effective width W is 120 cm or more, and the index K is 0.027 N- ^{1 / 2} or less.

FIG. 4 is a graph showing frequency weighting characteristics of noise. Excitation frequency of the longitudinal vibration _{V V} by vibro-hammer 6 shown in FIGS. 5A and 5B is generally about 20 Hz ~ 60 Hz. When the frequency of the membrane vibration V _M when flutter hat-shaped steel sheet pile 1 has occurred is to match the excitation frequency, the frequency of the membrane vibration V _M also becomes 20 Hz ~ 60 Hz. According to the human auditory characteristic shown as the A characteristic in FIG. 4, the perceived sound pressure level (dB) decreases as the frequency decreases in this frequency range. low frequency of vibration V _M is not only the improvement of workability, it is effective in reducing noise. The construction tests which we have carried out, by lowering the frequency of the membrane vibration V _M, noise reduction comparable to reduction in relative response shown in FIG. 4 have been identified.

According to the embodiment of the present invention described above, a hat-shaped steel sheet pile having a cross-sectional shape in which flapping occurring during driving is effectively reduced is provided. Such a hat-shaped steel sheet pile is, for example, a steel sheet pile wall including a step of driving the hat-shaped steel sheet pile into the ground while applying longitudinal vibration in the driving direction of the hat-shaped steel sheet pile using a vibro hammer as described above. Is particularly advantageous. What has been described above with reference to FIGS. 5A and 5B is a so-called double-chuck type vibratory hammer that applies longitudinal vibration to both flange portions of a hat-shaped steel sheet pile (for example, see Japanese Patent No. 3916621). If the fluttering generated at the time of driving is reduced by the embodiment of the present invention, a so-called single-chuck type vibratory hammer that applies longitudinal vibration to the web portion of the hat-shaped steel sheet pile is also possible.

Although the preferred embodiments of the present invention have been described above in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can conceive various changes or modifications within the scope of the technical idea described in the claims. It is understood that these also belong to the technical scope of the present invention.

1 ... hat-shaped steel sheet pile, 1P ... hat-shaped steel sheet pile, 2 ... web, 3A, 3B ... flange, 4A, 4B ... arm, 5A, 5B ... fitting joint, _{E A,} E B _... fitting center.

Claims

A hat-shaped steel sheet pile,
In a cross section orthogonal to the longitudinal direction, a web extending along the width direction on the first side in the thickness direction, and both ends in the width direction from both ends in the width direction of the web, and second portions in the thickness direction. And a pair of flanges extending toward the second side in the thickness direction, and extending from the respective ends of the pair of flanges on the second side in the thickness direction along the width direction and toward both sides in the width direction. A pair of arms, and a pair of mating joints formed at opposite ends of each of the pair of arms from the pair of flanges;
A total length B TTL (cm) of the web, the pair of flanges, and the pair of arms in the cross section having an effective width W of 105 cm or more, and a unit on a side surface parallel to the longitudinal direction. A hat-shaped steel sheet pile whose weight per unit area (wt / N / cm 2 ) satisfies the following expression (i).
The hat-shaped steel sheet pile according to claim 1, wherein the effective width W is equal to or greater than 120 cm, and the total length B TTL and the weight wt satisfy a relationship represented by the following expression (ii).
A method of manufacturing a steel sheet pile wall using the hat-shaped steel sheet pile according to claim 1 or 2,
A method for manufacturing a steel sheet pile wall, comprising a step of driving the hat-shaped steel sheet pile into the ground while giving longitudinal vibration in the driving direction of the hat-shaped steel sheet pile using a vibratory hammer.