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

Abstract

This effectively reduces the flapping that occurs when hat-shaped steel sheet piles are driven. [Solution] The hat-shaped steel sheet pile has, in a cross section perpendicular to the longitudinal direction, a web extending along the width direction on a first side in the thickness direction, a pair of flanges extending from both ends of the web in the width direction to both sides in the width direction and toward a second side in the thickness direction, a pair of arms extending from each end 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, and a pair of fitting joints formed at the end of each of the pair of arms opposite to the pair of flanges, and has an effective width W of 105 cm or more, and a total length B of the web, the pair of flanges, and the pair of arms in the cross section TTL (cm) and the weight of the hat-shaped steel sheet pile per unit area on the side parallel to the longitudinal direction wt (N / cm 2 ) satisfies formula (i). TIFF2022120069000011.tif19137

Description

[Technical Field]

[0001] The present invention relates to a hat-shaped steel sheet pile and a method for manufacturing a steel sheet pile wall. [Background technology]

[0002] Hat-shaped steel sheet piles are widely used in civil engineering and construction work to construct walls for earth retaining and watertight protection. Various technologies have been proposed to improve the workability and cross-sectional performance of hat-shaped steel sheet piles. For example, Patent Document 1 describes a technology for providing an economical hat-shaped steel sheet pile with a small unit weight while ensuring cross-sectional performance, by specifying the relationship between the unit weight per meter of wall width of the steel sheet pile wall and the moment of inertia of the steel sheet pile, and the relationship between the effective width and flange width of the hat-shaped steel sheet pile. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3458109 Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, when a hat-shaped steel sheet pile is driven by the vibro hammer method as shown in Figures 5A and 5B, flapping may occur in the hat-shaped steel sheet pile. As shown in Figure 5A, the vibro hammer method uses a vibro hammer 6 to apply vertical vibration V to the hat-shaped steel sheet pile 1 in the driving direction (z direction in the figure). V In this type of vibro hammer method, the concrete is driven while applying a vertical vibration V. V The direction of the membrane vibration V M As shown in Fig. 5B, the membrane vibration V MWhen the vibration is amplified to the extent that it can be seen, it is called flapping of the hat-shaped steel sheet pile1.

[0005] When the hat-shaped steel sheet pile 1 flutters as described above, the membrane vibration V M As a result, the joints of the hat-shaped steel sheet pile 1, which vibrates in the thickness direction (y direction in the figure), are driven into the joints of the hat-shaped steel sheet pile 1P, which does not vibrate, which may increase noise and damage the joints. M This may impair the straightness of the hat-shaped steel sheet pile 1 in the driving direction (z direction in the figure), which may lead to a deterioration in construction quality. Therefore, it is desirable to reduce the flapping in the construction of the hat-shaped steel sheet pile 1, but a method for achieving this is not disclosed in prior art such as Patent Document 1.

[0006] Therefore, an object of the present invention is to provide a new and improved method for manufacturing a hat-shaped steel sheet pile and a steel sheet pile wall that can effectively reduce the flapping that occurs when the hat-shaped steel sheet pile is driven. [Means for solving the problem]

[0007] According to an aspect of the present invention, a hat-shaped steel sheet pile has, in a cross section perpendicular to the longitudinal direction, a web extending along the width direction on a first side in the thickness direction, a pair of flanges extending from both ends of the web in the width direction to both sides in the width direction and toward a second side in the thickness direction, a pair of arms extending from each end 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, and a pair of fitting joints formed at ends of the pair of arms opposite to the pair of flanges, and has an effective width W of 105 cm or more, and a total length B of the web, the pair of flanges, and the pair of arms in the cross section TTL (cm) and the weight of the hat-shaped steel sheet pile per unit area on the side parallel to the longitudinal direction wt (N / cm 2 ) satisfy the relationship of the following formula (i).

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[0008] In the above hat-shaped steel sheet pile, the effective width W is 120 cm or more and the total length B TTL and the weight wt may satisfy the relationship of the following formula (ii):

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[0009] According to another aspect of the present invention, there is provided a method for manufacturing a steel sheet pile wall using the above-mentioned hat-shaped steel sheet pile. The method for manufacturing a steel sheet pile wall may include a step of driving the hat-shaped steel sheet pile into the ground while applying vertical vibrations to the hat-shaped steel sheet pile in the driving direction using a vibrating hammer.

[0010] According to the above configuration, it is possible to effectively reduce flapping that occurs when driving a hat-shaped steel sheet pile. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view of a hat-shaped steel sheet pile according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram for explaining the fitting center of the hat-shaped steel sheet pile shown in FIG. [Figure 3] 10 is a graph showing the effective width on the vertical axis and an index relating to the frequency of membrane vibration on the horizontal axis for the comparative example and the working example. [Figure 4] 1 is a graph showing frequency weighting characteristics of noise. [Figure 5A] FIG. 10 is a diagram for explaining flapping that occurs when a hat-shaped steel sheet pile is driven. [Figure 5B] FIG. 10 is a diagram for explaining flapping that occurs when a hat-shaped steel sheet pile is driven. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0013] Fig. 1 is a cross-sectional view of a hat-shaped steel sheet pile according to one embodiment of the present invention. As shown in Fig. 1, the hat-shaped steel sheet pile 1 includes, in a cross section perpendicular to the longitudinal direction (z direction in the figure), a web 2 extending along a width direction (x direction in the figure) on a first side in the thickness direction (the rear side in the y direction in the figure), flanges 3A and 3B extending from both ends of the web 2 in the width direction to both sides in the width direction and toward a second side in the thickness direction (the front side in the y direction in the figure) and forming a flange angle θ (acute angle side) with the width direction, arms 4A and 4B extending along the width direction from the ends of the flanges 3A and 3B on the second sides in the thickness direction and toward both sides in the width direction, and fitting joints 5A and 5B formed at the ends of the arms 4A and 4B opposite to the flanges 3A and 3B.

[0014] 1 shows the dimensions of each part of the hat-shaped steel sheet pile 1, specifically, the length Bw and thickness tw of the web 2, the length Bf of the flanges 3A and 3B, and the length Ba of the arms 4A and 4B. Here, the length Bw is the distance between two intersections formed between the thickness center line of the web 2 and each 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 each of the web 2 and the arm 4A. Furthermore, the length Ba is the distance between the intersections formed between the thickness center line of the arm 4A and the thickness center line of the flange 3A and each of the fitting center E of the fitting joint 5A. A Since the cross-sectional shape of the hat-shaped steel sheet pile 1 is symmetrical about the neutral axis in the width direction (y-axis in the figure), the flange 3B also has a length Bf like the flange 3A, and the arm 4B also has a length Ba like the arm 4A.

[0015] Furthermore, Figure 1 shows the effective width W and total length B of the hat-shaped steel sheet pile 1. TTLHere, the effective width W is the distance between the fitting centers E of the fitting joints 5A and 5B. A ,E B The total length B is the distance between TTL is the total length of the web 2, flanges 3A and 3B, and arms 4A and 4B in the cross section shown in the figure, and B is calculated using the length Bw, the length Bf, and the length Ba. TTL As will be described later, in the hat-type steel sheet pile 1 according to this embodiment, the effective width W is 105 cm or more and the total length B TTL and the weight wt of the hat-shaped steel sheet pile 1 per unit area on the side parallel to the longitudinal direction satisfy a predetermined relationship.

[0016] When the shape of the hat-shaped steel sheet pile 1 shown in Fig. 1 is geometrically valid, the effective width W, web length Bw, cross-sectional height H, and flange angle θ satisfy the relationship W-Bw-2H / tanθ>0. Here, the cross-sectional height H is the height of the cross section of the hat-shaped steel sheet pile 1, including the plate thicknesses of the web 2 and arms 4A and 4B but excluding the overhangs of the fitting joints 5A and 5B.

[0017] 2 is a diagram for explaining the fitting center of the hat-shaped steel sheet pile shown in FIG. 1. As shown in the figure, a fitting joint 5A of a hat-shaped steel sheet pile 1 is fitted with a fitting joint 5B of another hat-shaped steel sheet pile 1 that is driven adjacently. The fitting center E of the fitting joint 5A A can be defined as a point on the design plate thickness center line of the arm 4A and the arm 4B, which is located midway between the end position of the arm 4A where the fitted joint 5A is formed and the end position of the arm 4B where the virtual fitted joint 5B is formed, when the arm 4B and the fitted joint 5B of another hat-shaped steel sheet pile 1 are virtually arranged. B can be defined similarly.

[0018] The results of the study conducted by the present inventors to effectively reduce the flapping that occurs during driving in the hat-type steel sheet pile according to the embodiment of the present invention will be described below. First, in order to reduce the flapping, the membrane vibration V that occurs in the thickness direction of the hat-type steel sheet pile 1 is M It is desirable to lower the frequency of the hat-type steel sheet pile 1 (see Figures 5A and 5B). It is known from experience that flapping occurs in the early stages of concrete pouring and gradually subsides as concrete pouring progresses. This is thought to be because the distance from the top of the hat-type steel sheet pile 1 to the ground surface is longest in the early stages of concrete pouring and gradually becomes shorter as concrete pouring progresses. The top of the hat-type steel sheet pile 1, which is gripped by the vibro hammer 6, and the part near the ground surface where the displacement in the thickness direction of the hat-type steel sheet pile 1 is restrained by the joints of the ground and another hat-type steel sheet pile 1P poured earlier, are both fixed points for vibration in the thickness direction of the hat-type steel sheet pile 1. Therefore, in the early stages of concrete pouring, when the distance between the fixed points is longest, the natural frequency of the hat-type steel sheet pile 1 is low, and at this stage the hat-type steel sheet pile 1 generates membrane vibration V M When the membrane resonates with the oscillating force, a low frequency vibration with a large amplitude occurs, resulting in membrane vibration V M In other words, the membrane vibration V M If the vibration frequency of is lower than the natural frequency of the hat-shaped steel sheet pile 1, the membrane vibration V M is not amplified. As the driving of the hat-shaped steel sheet pile 1 progresses and the distance between the fixed points becomes shorter, the natural frequency becomes higher. Therefore, in the early stage of driving, the membrane vibration V M If the vibration frequency of the hat-shaped steel sheet pile 1 is lower than the natural frequency of the hat-shaped steel sheet pile 1, the membrane vibration V M No amplification of the load, i.e., flapping of the hat-shaped steel sheet pile 1, occurs.

[0019] Frequency f of membrane vibration in a rectangular plate with side lengths a and b mn can be expressed as the following formula (1) using the mode numbers m and n, the gravitational acceleration g, the weight of the plate per unit area wt, and the in-plane tension S. From formula (1), the larger the weight wt and the longer the side lengths a and b, the lower the frequency f mn becomes smaller, that is, the membrane vibration becomes lower frequency.

[0020]

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[0021] Here, the membrane vibration is made lower in frequency than that of the conventional hat-shaped steel sheet pile, for example, i.e., the membrane vibration frequency f mn ' is the membrane vibration frequency f of the conventional hat-shaped steel sheet pile mn Consider the conditions for making the vibration frequency smaller than . In the fundamental mode (m=n=1), when the weight w and side length a are different but other conditions are the same, the ratio f' / f of the membrane vibration frequency to that of a conventional hat-type steel sheet pile can be expressed as the following formula (2). Note that for higher modes (m>1 or n>1), the amplitude is small and therefore it is not necessary to consider them as a cause of flapping of the hat-type steel sheet pile 1.

[0022]

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[0023] Furthermore, when a rectangular plate with side lengths a and b is applied to the shape of a hat-shaped steel sheet pile, the longitudinal side length b of the hat-shaped steel sheet pile is sufficiently longer than the cross-sectional side length a (at the beginning of casting, the side length b is 10 times or more the side length a), so (a' / b) in formula (2) 2 and (a / b) 2 The term is small enough that it can be ignored. As a result, the frequency ratio f' / f can be expressed as the following equation (3):

[0024]

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[0025] According to the above formula (3), in order to reduce the ratio f' / f of the membrane vibration frequency of the hat-shaped steel sheet pile 1 to that of the conventional hat-shaped steel sheet pile, the side length a in the cross-sectional direction of the hat-shaped steel sheet pile, that is, the total length B shown in Figure 1, TTLor increase the weight wt of the hat-shaped steel sheet pile 1 per unit area on the side parallel to the longitudinal direction (average value of the web 2, flanges 3A, 3B, and arms 4A, 4B). In other words, if K (an index related to membrane vibration of the hat-shaped steel sheet pile 1) defined as the following formula (4) is smaller in the hat-shaped steel sheet pile 1 than in the conventional hat-shaped steel sheet pile, membrane vibration will be reduced. First, the total length B TTL Regarding the width, it can be increased by expanding the effective width W of the hat-shaped steel sheet pile 1. Increasing the effective width W reduces the number of hat-shaped steel sheet piles 1 that make up the steel sheet pile wall of the same wall width, making construction more economical. Therefore, in the following, the effective width W is set to 105 cm or more, and the appropriate total length B TTL and weight wt were considered.

[0026]

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[0027] Table 1 shows the cross-sectional specifications of the conventional hat-shaped steel sheet piles (Comparative Examples 1 to 3) and the hat-shaped steel sheet piles according to the embodiments of the present invention (Examples 1 to 9). In Table 1, W is the effective width (cm), I is the moment of inertia (cm) per 1 m of wall width of the steel sheet pile wall. 4 / m), B TTL is the total length (cm), wt (N / cm 2 ) is the weight per unit area on the side parallel to the longitudinal direction, K(N -1 / 2 ) is an index calculated by the above formula (4). Also, the frequency ratio r f is the ratio of the membrane vibration frequency between each example and a conventional hat-shaped steel sheet pile with the same moment of inertia I, calculated by multiplying the side length a by the total length B in the above formula (3). TTL It is calculated by substituting

[0028] [Table 1]

[0029] FIG. 3 shows the relationship between the effective width W (cm) on the vertical axis and the K (N -1 / 2 3, in Examples 1 to 9, the effective width W is 105 cm or more, and the index K calculated by the formula (4) is 0.030 N. -1 / 2 In the hat-shaped steel sheet piles of Examples 1 to 9, the vibration frequency ratio r f is below 1, and the membrane vibration is at a lower frequency than in Comparative Examples 1 to 3. f In Examples 2, 3, 5, 6, 8, and 9, in which the effective width W is less than 0.9 and the membrane vibration frequency is significantly lower than that of Comparative Examples 1 to 3, the effective width W is 120 cm or more and the index K is 0.027 N. -1 / 2 The following is the result.

[0030] 4 is a graph showing the frequency weighting characteristics of noise. V The excitation frequency of the membrane vibration V is generally about 20Hz to 60Hz. M If the frequency of the membrane vibration V is equal to the excitation frequency, M The vibration frequency of the membrane vibration V according to the embodiment of the present invention as described above is also 20 Hz to 60 Hz. According to the human hearing characteristics shown as A-weighting in FIG. 4, the perceived sound pressure level (dB) decreases as the frequency decreases in this frequency range. M The lowering of the frequency of the membrane vibration V is effective not only for improving workability but also for reducing noise. M It has been confirmed that by lowering the frequency, noise reduction is equivalent to the decrease in relative response shown in Figure 4.

[0031] According to the embodiment of the present invention described above, a hat-shaped steel sheet pile having a cross-sectional shape that effectively reduces flapping during driving is provided. Such a hat-shaped steel sheet pile is particularly advantageous in a method for manufacturing a steel sheet pile wall, which includes, for example, the step of driving the hat-shaped steel sheet pile into the ground while applying vertical vibrations to the hat-shaped steel sheet pile in the driving direction using a vibro hammer, as described above. The so-called double-chuck vibro hammer (see, for example, Japanese Patent No. 3916621) that applies vertical vibrations to both flange portions of the hat-shaped steel sheet pile has been described above with reference to Figures 5A and 5B. However, if flapping during driving can be reduced by the embodiment of the present invention, construction using a so-called single-chuck vibro hammer that applies vertical vibrations to the web portion of the hat-shaped steel sheet pile is also possible.

[0032] Although the preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention. [Explanation of symbols]

[0033] 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 ...Mating center.

Claims

1. A hat-shaped steel sheet pile, In a cross section perpendicular to the longitudinal direction, the sheet comprises: a web extending along a width direction on a first side in a thickness direction; a pair of flanges extending from both ends of the web in the width direction to both sides in the width direction and toward a second side in the thickness direction; a pair of arms extending from 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; and a pair of fitting joints formed at ends of the pair of arms opposite the pair of flanges, The effective width W is 105 cm or more, and the total length B of the web, the pair of flanges, and the pair of arms in the cross section ＴＴＬ (cm), and the weight wt (N / cm) of the hat-shaped steel sheet pile per unit area on the side parallel to the longitudinal direction ２ ) and the hat-shaped steel sheet pile satisfy the relationship of the following formula (i). [Equation 1]

2. The effective width W is 120 cm or more, and the total length B ＴＴＬ and the weight wt satisfy the relationship of the following formula (ii). [Equation 2]

3. A manufacturing method of 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 the step of driving the hat-shaped steel sheet pile into the ground while applying vertical vibration to the hat-shaped steel sheet pile in the driving advance direction using a vibrating hammer.

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