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

Abstract

This improves workability by reducing the torsional deformation within the cross section that occurs above ground when hat-shaped steel sheet piles are installed. [Solution] The hat-shaped steel sheet pile, in a cross section perpendicular to the longitudinal direction, comprises a web extending along the width direction on a first side in the depth 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 depth direction, a pair of arms extending from each end of the pair of flanges on the second side in the depth direction along the width direction and toward both sides in the width direction, and fitting joints formed at the ends of the pair of arms opposite to the pair of flanges. The cross-sectional area Ae (cm 2 ), the effective width W (cm) of the hat-shaped steel sheet pile 1, and the height H (cm) of the hat-shaped steel sheet pile 1 satisfy the relationship of the following formula (i), and the effective width W is 110 cm or more. Ae / (W H) ≥ 0.04 (i)

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 projects to construct earth-retaining and water-stopping walls. Because hat-shaped steel sheet piles penetrate the ground during driving, techniques have been proposed to improve workability by reducing penetration resistance. For example, Patent Document 1 describes a technique for suppressing earth discharge pressure during driving and improving workability by setting the flange angle, i.e., the angle between the flange and the web and arm, so that the intersection of perpendicular lines passing through the centers of each flange in the cross section of the hat-shaped steel sheet pile is located outside the cross section of the hat-shaped steel sheet pile's groove. Patent Document 2 also describes a technique for minimizing penetration resistance by optimizing the flange angle. Patent Document 3 describes a technique for setting the flange angle based on an economic index and a workability index that indicates the penetration resistance at the bottom end of the steel sheet pile. Patent Document 4 describes a technique for setting the cross-sectional shape of a steel sheet pile that exhibits excellent performance in at least one of economy and workability, based on the relationship between an economic evaluation index and a workability evaluation index that indicates the ratio of the blockage resistance acting on the bottom end of the steel sheet pile during driving to the cross-sectional area. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3488230 [Patent Document 2] Patent No. 3488233 [Patent Document 3] Patent No. 5764945 [Patent Document 4] Japanese Patent Application Laid-Open No. 2014-148798 Summary of the Invention [Problem to be solved by the invention]

[0004] The technologies described in Patent Documents 1 to 4 all focus on the underground behavior of steel sheet piles and aim to improve their workability by reducing the penetration resistance and blockage resistance that act after the pile is driven into the ground. Previous methods for evaluating the workability of steel sheet piles focused solely on the mechanism of insertion into the ground, exploring the optimal shape of the steel sheet pile based on the relationship between the ground resistance and soil particle behavior around the steel sheet pile. However, according to the findings of the present inventors, in addition to the underground behavior of the steel sheet pile, its aboveground behavior during installation also affects its workability. In other words, the actual installation of a steel sheet pile involves a parallel progression of the steel sheet pile being driven into the ground and projecting above ground, and the workability of the steel sheet pile is affected by the coupled behavior of the steel sheet pile in the ground and above ground. Specifically, it was found that when steel sheet piles are cast while being connected widthwise with joints, torsional deformation occurs in the cross section of the hat-shaped steel sheet piles that are cast with the joints restrained on the previously cast steel sheet piles, reducing workability.

[0005] Specifically, if a hat-shaped steel sheet pile experiences deformation such as twisting or bending, it may increase the penetration resistance from the ground below the bottom end of the sheet pile and from the sides of the pile during installation, as well as the engagement resistance with the joints of previously installed steel sheet piles. Furthermore, if deformation such as bending or twisting occurs in the hat-shaped steel sheet pile above ground, the construction equipment, such as a vibrohammer, may tilt or oscillate. This may result in the vibration energy of the construction equipment, which is normally used to vibrate the hat-shaped steel sheet pile vertically, being lost as energy in the horizontal vibration and rotational behavior of the hat-shaped steel sheet pile, resulting in a decrease in the penetration speed of the hat-shaped steel sheet pile into the ground. If the construction equipment tilts or oscillates, a horizontal load is applied to the head of the steel sheet pile, which may exacerbate the deflection and twisting behavior of the steel sheet pile, further increasing the loss of vibration energy, creating a vicious cycle. Therefore, in order to ensure good workability of steel sheet piles, it is important to suppress the deflection and torsional deformation of the steel sheet piles not only in the ground but also above ground.

[0006] However, the behavior of hat-shaped steel sheet piles above ground, which could cause a decrease in workability, is not described in the above-mentioned Patent Documents 1 to 4. When evaluating the driveability of steel sheet piles, the optimal cross-sectional shape of the steel sheet pile has not been explored by considering not only the behavior in the ground but also the overall behavior of the steel sheet pile, including the aboveground portion. This is because, when the cross-section of a steel sheet pile is small, the position where the construction machine supports the steel sheet pile is not significantly eccentric from the center of gravity of the cross-section of the steel sheet pile, and therefore, deformation such as bending or twisting of the steel sheet pile that affects workability is unlikely to occur above ground. Therefore, it has been thought that the workability of steel sheet piles is dominated by resistance from the ground. In fact, when steel sheet piles are small, the cross-sectional deformation of the steel sheet pile during driving is not significantly exposed above ground. Therefore, the relationship between deformation behavior above ground and workability has not been paid attention to, and there has been no knowledge regarding the relationship between the two. However, in recent years, as the cross section of hat-shaped steel sheet piles has become larger, deformation behavior such as torsion and deflection of the hat-shaped steel sheet piles at above ground level has increased, which may affect construction workability.

[0007] Therefore, the present invention aims to provide a new and improved method for manufacturing hat-shaped steel sheet piles and steel sheet pile walls that can improve workability by reducing the torsional deformation in the cross section that occurs in the above-ground part when the hat-shaped steel sheet pile is driven. [Means for solving the problem]

[0008] According to one aspect of the present invention, a hat-shaped steel sheet pile comprises, in a cross section perpendicular to the longitudinal direction, a web extending along the width direction on a first side in the depth 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 depth direction, a pair of arms extending from each end of the pair of flanges on the second side in the depth direction along the width direction and toward both sides in the width direction, and fitting joints formed at the ends of the pair of arms opposite to the pair of flanges. 2), the effective width W (cm) of the hat-shaped steel sheet pile, and the height H (cm) of the hat-shaped steel sheet pile satisfy the relationship of the following formula (i), The effective width W is 110 cm or more. Ae / (W H) ≥ 0.04 (i)

[0009] In the above hat-shaped steel sheet pile, the effective width W may be 135 cm or more, and the height H may be 45 cm or less. 2 ), the effective width W (cm), and the height H (cm) may satisfy the relationship of the following formula (ii): Ae / (W H)≦0.048 (ii) In addition, the moment of inertia per 1m of wall width of a wall made of hat-shaped steel sheet piles connected in the width direction is 50,000 cm 4 It may be at or below the / m level.

[0010] 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 fitting only one of the fitting joints of the hat-shaped steel sheet pile into the fitting joint of a steel sheet pile that has been driven previously.

[0011] According to the above-mentioned configuration, workability can be improved by reducing torsional deformation in the cross section that occurs in the above-ground part when driving the hat-shaped steel sheet pile. [Brief explanation of the drawings]

[0012] [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 a fitting center in a fitting joint of the hat-shaped steel sheet pile shown in FIG. [Figure 3] This is a diagram showing the boundary conditions of the hat-shaped steel sheet pile during driving, and conceptually explaining the fitting condition with the preceding sheet pile and the gripping condition of the hat-shaped steel sheet pile by the vibro hammer. [Figure 4]1 is a diagram for conceptually explaining the horizontal torsional deformation that occurs in a hat-shaped steel sheet pile during driving. FIG. [Figure 5] 1 is a graph plotting comparative examples, examples, and reference examples of the present invention with the effective width W on the horizontal axis and the ratio Ae / (W·H) of the cross-sectional area Ae to the product of the effective width W and height H on the vertical axis. [Figure 6] This graph shows only examples in which the effective width W is 135 cm or more, extracted from the examples shown in the graph of FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0013] 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.

[0014] 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 the width direction (x direction in the figure) on a first side in the depth 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 depth 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 depth 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, respectively.

[0015] As will be described later, the cross-sectional area Ae of the hat-shaped steel sheet pile 1 in this cross section (the area of ​​the hatched region in the drawing), the effective width W of the hat-shaped steel sheet pile 1, and the height H of the hat-shaped steel sheet pile 1 satisfy the relationship of the following formula (1), and the effective width W is 110 cm or more. Note that the effective width W is the distance between the fitting centers E of the fitting joints 5A and 5B in the cross section. A ,E BThe height H is equal to the distance between the first side surface in the depth direction of the web 2 (the rear side in the y direction in the drawing) which coincides with the width direction of the hat-shaped steel sheet pile 1, and the second side surface in the depth direction of the arms 4A and 4B (the front side in the y direction in the drawing) which also coincides with the width direction of the hat-shaped steel sheet pile 1. Ae / (W H) ≥ 0.04 (1)

[0016] Note that the "second side surface in the depth direction of the arms 4A and 4B" used to determine the height H may not strictly coincide with the actual surfaces of the arms 4A and 4B due to manufacturing errors and other factors. However, even in such cases, the surfaces of the arms 4A and 4B may be collinear in the cross section of the hat-shaped steel sheet pile 1 shown in the design drawings, and this surface may be identified as the "second side surface in the depth direction of the arms 4A and 4B." In this case, the extension direction of the arms 4A and 4B shown in the design drawings coincides with the width direction of the hat-shaped steel sheet pile 1. Furthermore, in the case of a hat-shaped steel sheet pile 1 driven into the ground after construction, due to deformation of the arms 4A and 4B during construction, for example, the "second side surface in the depth direction of the arms 4A and 4B" may not strictly coincide with the actual surfaces of the arms 4A and 4B at the head end surface of the hat-shaped steel sheet pile 1 exposed above ground. However, even in this case, for example, the faces of the arms 4A and 4B shown on the same line in the design drawing showing the state before casting can be specified as "the second side faces in the depth direction of the arms 4A and 4B." If the design drawing is not used, the fitting center E located at each end of the arms 4A and 4B on the head end face of the hat-shaped steel sheet pile 1 exposed on the ground can be specified as "the second side faces in the depth direction of the arms 4A and 4B." A ,E B The straight line connecting these points is taken as the design thickness center line of arms 4A and 4B, and by translating this line by half the thickness of arms 4A and 4B toward the second side in the depth direction, the "surface on the second side in the depth direction of arms 4A and 4B" can be identified.

[0017] When the shape of the hat-shaped steel sheet pile 1 shown in Figure 1 is geometrically valid, the arm length Ba, effective width W, web length Bw, height H and flange angle θ satisfy the relationship W-Bw-2H / tanθ>0.

[0018] 2 is a diagram for explaining the fitting center of the fitting joint 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 When the arm 4B and the fitting joint 5B that fit thereto are virtually arranged, the fitting center E of the arm 4A and the arm 4B is located midway between the end position of the arm 4A where the fitting joint 5A is formed and the end position of the arm 4B where the virtual fitting joint 5B is formed. B can be defined in the same way. As mentioned above, the fitting center E A ,E B The distance between them is equal to the effective width W of the hat-shaped steel sheet pile 1.

[0019] 3 and 4 are diagrams for conceptually explaining the horizontal torsional deformation that occurs in a hat-shaped steel sheet pile during driving. As shown in Fig. 3, the hat-shaped steel sheet pile 1 is driven by a vertical load applied from a vibro hammer 6 that clamps the flanges 3A and 3B at the upper end. In order to stably support the hat-shaped steel sheet pile 1, the vibro hammer 6 is positioned so that its position in the depth direction (y direction in the figure) approximately coincides with the centroid C of the cross section.

[0020] Here, a hat-shaped steel sheet pile 1P has been driven in advance near the ground surface, and the hat-shaped steel sheet pile 1 is driven while fitting the fitting joint 5A into the fitting joint 5B of the hat-shaped steel sheet pile 1P. Therefore, near the ground surface, the fitting joint 5A of the hat-shaped steel sheet pile 1 is restrained from horizontal displacement by the fitting joint 5B of the hat-shaped steel sheet pile 1P. The fitting joint 5A is located at the fitting center E with the fitting joint 5B. AThe horizontal displacement is restrained by contact at multiple points near the pile. Therefore, the hat-shaped steel sheet pile 1 is restrained by the fitted joint and the ground at the longitudinal lower part protruding above ground. On the other hand, since the centroid C, which is the point of application of the load from the vibro hammer 6, is located away from the restraint point of the horizontal displacement as described above, a bending moment is generated in the hat-shaped steel sheet pile 1 in the direction of twisting the cross section.

[0021] Here, the fitting center E A The distance between the center of gravity C and the centroid C differs between the width direction (x direction in the figure) and the depth direction (y direction in the figure) of the hat-shaped steel sheet pile 1, so the magnitude of the bending moment generated in each direction differs. Furthermore, the second moment of area of ​​the hat-shaped steel sheet pile 1 differs in each direction, resulting in a difference in the deflection generated in each direction, resulting in torsional deformation within the cross section. Because the upper and lower ends of the hat-shaped steel sheet pile 1 are restrained by the vibrohammer 6 and the ground, respectively, the above-mentioned bending moment generates a predominant pure torsion compared to the warp torsion in the hat-shaped steel sheet pile 1. As shown in Figure 4, the torsional angle φ of pure torsion centered at any point within the cross section of the hat-shaped steel sheet pile 1 is expressed by the following equation (2). Mt is the bending moment around the center of pure torsion, G is the shear modulus of elasticity of the hat-shaped steel sheet pile 1, and J is the cross-sectional torsional moment of the hat-shaped steel sheet pile 1. φ=Mt / (G J) (2)

[0022] Generally, the fitting joints 5A and 5B are designed to allow a certain degree of torsion angle φ. However, if φ becomes large, the friction generated between the fitting joint 5A of the hat-shaped steel sheet pile 1 to be driven and the fitting joint 5B of the hat-shaped steel sheet pile 1P driven in advance increases, which may cause damage to the fitting joints 5A and 5B or increase resistance during driving, which may reduce workability.

[0023] From the viewpoint of the economic efficiency of the cross section of the hat-shaped steel sheet pile 1, it is advantageous to increase the effective width W while thinning the wall thickness. However, thinning the wall thickness reduces the cross-sectional area resisting the bending moment, which reduces the cross-sectional torsional moment resisting the bending moment and reduces the torsional rigidity, thereby increasing the torsion angle φ. Therefore, it is effective to ensure a certain cross-sectional area. When increasing the effective width W, it is necessary to ensure the cross-sectional torsional moment J by adjusting the thicknesses of the web 2, flanges 3A and 3B, and arms 4A and 4B within the range of the effective width and height of a single hat-shaped steel sheet pile 1. However, since increasing the thickness reduces the economic efficiency of the cross section, it is desirable to have a simple indicator of the required plate thickness.

[0024] In view of the above, the inventors have studied an index of the cross-sectional shape of a hat-type steel sheet pile 1 that can reduce the torsion angle φ compared to conventional hat-type steel sheet piles while increasing the effective width W compared to conventional hat-type steel sheet piles, by applying a state in which the longitudinal displacement of the hat-type steel sheet pile is fixed at the upper and lower longitudinal ends, and a pure torsion of the thin-walled open cross section occurs in the longitudinal above-ground portion of the hat-type steel sheet pile 1 against a moment that rotates the cross section about the longitudinal axis. The following study is intended to simply identify the conditions of the cross-sectional shape of the hat-type steel sheet pile 1 that can reduce the torsion angle φ by using the cross-sectional area Ae as a parameter that reflects the plate thicknesses of the web 2, flanges 3A, 3B, and arms 4A, 4B, and the effective width W and height H of the hat-type steel sheet pile 1 as parameters that reflect the magnitude of the bending moment Mt.

[0025] The results of the study are shown in Tables 1 to 4. The study was conducted by calculating the moment of inertia I per 1 m of wall width of a wall in which hat-shaped steel sheet piles 1 were connected in the width direction. W is 10,000 cm 4 / m level, 25000cm 4 / m level, 45000cm 4 / m level, and 50,000 cm 4The tests were performed for each of the cases with a twist angle of 1 / m. Examples 1 to 21 show examples in which the torsion angle φ is reduced compared to that of conventional hat-shaped steel sheet piles, as shown in Comparative Examples 1 to 4, and Reference Examples 1 to 14 show examples in which the torsion angle φ is increased compared to that of conventional hat-shaped steel sheet piles. As described above, in this embodiment, the effective width W is intended to be larger than that of conventional hat-shaped steel sheet piles. Therefore, in all of Examples 1 to 21, the effective width W of the hat-shaped steel sheet pile 1 is 110 cm or more. The dimensions represented by the web thickness tw (cm), web width Bw (cm), and arm width Ba (cm) shown in Tables 1 to 4 are also shown in Figure 1. As described above, when the effective width W of the hat-shaped steel sheet pile 1 is increased to satisfy the performance of a steel sheet pile with less twist compared to conventional hat-shaped steel sheet piles and to pursue economic benefits, it is desirable to keep the height H small relative to the effective width W in order to ensure productivity from the standpoint of formability, etc., and a cross section with a height of 45 cm or less is pursued. Therefore, in Examples 1 to 21, the height H is 45 cm or less (the largest is Example 21, where H = 40.2 cm). Even if the effective width is wide and the height is low, the aim is to form a cross section that satisfies the specified torsion resistance performance by setting the ratio of the cross-sectional area to the effective width and height within a specified range.

[0026] [Table 1]

[0027] [Table 2]

[0028] [Table 3]

[0029] [Table 4]

[0030] FIG. 5 is a graph plotting the above Comparative Examples 1 to 4, Examples 1 to 21, and Reference Examples 1 to 14, with the effective width W (cm) on the horizontal axis and the ratio Ae / (W·H) of the cross-sectional area Ae to the product of the effective width W and the height H on the vertical axis.

[0031] Here, we will explain the indexes using the cross-sectional dimensions of the hat-shaped steel sheet pile, which are set as the axes of the graph in Figure 5. The bending moment that generates torsion in the hat-shaped steel sheet pile is A The torsion angle φ increases in proportion to the distance in the width direction and the depth direction between the center of gravity C and the center of gravity C. The magnitude of the torsion angle φ is proportional to the bending moment and inversely proportional to the cross-sectional torsion moment. Therefore, regarding the magnitude of the bending moment, A The effective width W and height H of the steel sheet pile cross section were used as indicators of the distance in the width direction and depth direction, respectively, between the center of gravity C and the centroid C, and the product of these two indicators was used to simultaneously include the effects of both indicators. The cross-sectional area Ae was also used as an indicator of the magnitude of the cross-sectional torsional moment.

[0032] To achieve an economical sheet pile cross-sectional area Ae within a given rolling area, it is preferable that the sheet pile cross-sectional area Ae relative to the given area be small. The given rolling area is proportional to the product of the effective width W and height H, which is the final shape of the sheet pile after rolling. Therefore, Ae / (W·H) is an index showing the economic efficiency of the sheet pile cross-section. In other words, Ae / (W·H) can be used as an index to determine the magnitude of the torsion angle φ as mentioned above, and can also be used as an index to evaluate economic efficiency. The graph in Figure 5 uses Ae / (W·H), a simple index that can evaluate two indices using only three items: cross-sectional area Ae, effective width W, and height H, as the vertical axis.

[0033] Specifically, to reduce the twist angle φ, it is advantageous to increase the value of Ae / (W·H), and to achieve an economical cross section, it is advantageous to decrease the value of Ae / (W·H). In other words, if the value of Ae / (W·H) is made too large, the twist angle φ will be small but economic efficiency will decrease, and conversely, if the value of Ae / (W·H) is made too small, economic efficiency will improve but the twist angle φ will increase. By using the Ae / (W·H) index, it is possible to balance the reduction of the twist angle φ and economic efficiency, that is, to easily determine both workability and economic efficiency at the same time.

[0034] On the other hand, in order to make the cross section of a hat-shaped steel sheet pile economical, it is effective to widen the width. This is because the web width can be increased and the area ratio of the flange portion to the given width can be reduced, so the moment of inertia per given width, i.e., bending rigidity, can be secured with a smaller cross-sectional area. Therefore, in the graph of Figure 5, the effective width W is plotted on the horizontal axis, taking into account the evaluation of economic efficiency relative to bending rigidity.

[0035] In the graph of FIG. 5 as described above, Comparative Examples 1 to 4 are shown as points P1 to P4, Examples 1 to 21 are shown as points E1 to E21, and Reference Examples 1 to 14 are shown as groups of points R1, R11 to R14, and points R2 to R10. Points E1 to E21 representing the Examples are within the range of Ae / (W·H)≧0.04. In contrast, points R2 to R10 representing the Reference Examples are within the range of Ae / (W·H)<0.04. On the other hand, points P1 to P4 representing the Comparative Examples and points R1, R11 to R14 representing the Reference Examples are within the range of W<110 cm. Therefore, from the above results, the following formula (1) can be identified as a condition for the cross-sectional shape of the hat-shaped steel sheet pile 1 that can reduce the torsion angle φ when the effective width W is 110 cm or more. Ae / (W H) ≥ 0.04 (1)

[0036] Here, it is preferable to make the hat-shaped steel sheet pile with a thin wall and large cross section, which has an expanded width, more compact in cross section when considering manufacturability. From this point of view, among the examples considered above, the moment of inertia I per 1 m of wall width of the wall body in which the hat-shaped steel sheet piles 1 are connected in the width direction is W is 25,000 cm 4 More preferable are those at the / m level or below, that is, Examples 1 to 8. In Examples 1 to 8, in addition to the above formula (1), the following formula (2) is satisfied. Ae / (W H)≦0.048 (2)

[0037] Figure 6 is a graph that extracts only examples with wider effective widths W of 135 cm or more from Examples 1 to 21 shown in the graph of Figure 5. Specifically, Examples 2 to 7, Examples 13 to 18, Examples 20, and Examples 21 are extracted. As with the graph of Figure 5, points E2 to E7, E13 to E18, E20, and E21 in the graph of Figure 6 are included in the range of Ae / (W·H) ≧ 0.04. Here, as shown in Tables 1, 3, and 4 above, Examples 2 to 7, Examples 13 to 18, Examples 20, and 21 not only have effective widths W of 135 cm or more, but also have torsion angles φ (compared to conventional examples) reduced to less than 0.95, i.e., less than 95% of that of conventional hat-shaped steel sheet piles, and are examples in which the torsion angle φ is reduced by a larger amount than in the other examples. Torsional deformation of a hat-shaped steel sheet pile during installation deteriorates the fit of the joints of the hat-shaped steel sheet piles installed in the ground beforehand. The tolerance of the fit angle of hat-shaped steel sheet pile joints is typically within a very narrow range of ±4°. Even in situations where the difference in the twist angle between cross sections at different depths in the longitudinal direction is only 1°, torsional deformation accumulates along the length of the hat-shaped steel sheet pile, leading to increased fit resistance. Therefore, even a very small reduction in torsion is useful. However, reducing the torsional deformation by even 5%, for example, can reduce the contact resistance of the hat-shaped steel sheet pile with the joints of the preceding steel sheet piles due to torsional deformation during installation of the subsequently installed hat-shaped steel sheet pile, thereby more effectively reducing the impact on workability. Therefore, the above formula (1) can be more advantageously applied as a cross-sectional shape condition that can significantly reduce the torsion angle φ for hat-shaped steel sheet piles 1 having an effective width W of 135 cm or more, where the torsion angle φ (compared to conventional ones) is less than 0.95.

[0038] According to the embodiment of the present invention described above, a hat-shaped steel sheet pile having a cross-sectional shape that effectively reduces torsional deformation in the cross section that occurs during driving is provided. Such a hat-shaped steel sheet pile is particularly advantageous in a method for manufacturing a steel sheet pile wall, for example, including a step of driving the hat-shaped steel sheet pile into the ground while fitting only one of a pair of fitting joints of the hat-shaped steel sheet pile into the fitting joint of a steel sheet pile previously driven. In such a method for manufacturing a steel sheet pile wall, the position at which the construction machine supports the steel sheet pile and applies a vertical vibration load is eccentric to the position at which one joint of the hat-shaped steel sheet pile fits into the joint of the steel sheet pile previously driven. Therefore, a moment that causes torsional deformation is likely to occur in the hat-shaped steel sheet pile. However, by applying the embodiment of the present invention, torsional deformation can be effectively suppressed.

[0039] By suppressing the torsional deformation of the hat-shaped steel sheet pile, the driving energy from the construction machine is transmitted to the hat-shaped steel sheet pile with little loss, making efficient use of the construction machine's power, allowing the penetration speed of the hat-shaped steel sheet pile into the ground to be maintained high and economical construction with good fuel efficiency of the construction machine becomes possible. In addition, by suppressing the torsional deformation of the hat-shaped steel sheet pile, the flapping of the hat-shaped steel sheet pile during driving is reduced, making it possible to reduce noise and vibration associated with construction. When the construction machine becomes larger due to the increase in the cross-section of the hat-shaped steel sheet pile, noise and vibration may also increase, but by suppressing the torsional deformation of the hat-shaped steel sheet pile, construction with reduced noise and vibration is possible.

[0040] In addition, by suppressing the torsional deformation of the hat-shaped steel sheet pile, the fitting resistance with the joint of the steel sheet pile that was cast earlier can be reduced, thereby reducing the resistance of the entire hat-shaped steel sheet pile when cast and preventing scraping and welding at the contact surface of the joint.

[0041] 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]

[0042] 1...Hat-shaped steel sheet pile, 2...Web, 3A, 3B...Flange, 4A, 4B...Arm, 5A, 5B...Fitting joint, 6...Vibro hammer, E A ,E B ...Mating center.

Claims

1. A hat-shaped steel sheet pile, In a cross section perpendicular to the longitudinal direction, the panel comprises: a web extending along the width direction on a first side in the depth 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 depth direction, the flanges forming a flange angle θ (θ≦72.5°) with the width direction; a pair of arms extending from each end of the pair of flanges on the second side in the depth direction along the width direction and toward both sides in the width direction; and fitting joints formed at the ends of each of the pair of arms opposite to the pair of flanges, The cross-sectional area Ae (cm ２ ), an effective width W (cm) of the hat-shaped steel sheet pile, and a height H (cm) of the hat-shaped steel sheet pile satisfy the relationship of the following formula (i), and the effective width W is 110 cm or more and 120 cm or less, The hat-shaped steel sheet pile is integrally formed without including any joints other than the fitting joints formed at the respective ends of the pair of arms in the cross section. Ae / (W・H)≧0.04...(i)

2. The hat-shaped steel sheet pile according to claim 1, wherein the height H is 45 cm or less.

3. The cross-sectional area Ae (cm ２ 3. The hat-shaped steel sheet pile according to claim 1 or 2, wherein the effective width W (cm) and the height H (cm) satisfy the relationship of the following formula (ii): Ae / (W・H)≦0.048...(ii)

4. The moment of inertia per 1 m of wall width of the wall body in which the hat-shaped steel sheet piles are connected in the width direction is 50,000 cm ４ The hat-shaped steel sheet pile according to any one of claims 1 to 3, wherein the cross section of the hat-shaped steel sheet pile is equal to or less than 1 / m level.

5. A manufacturing method of a steel sheet pile wall using the hat-shaped steel sheet pile according to any one of claims 1 to 4, A method for manufacturing a steel sheet pile wall, comprising: driving the hat-shaped steel sheet pile into the ground while fitting only one of the fitting joints of the hat-shaped steel sheet pile into the fitting joint of a steel sheet pile that has been driven in advance.

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