JP4890646B2 - Combination steel sheet pile, retaining wall composed of combination steel sheet pile, and method for selecting combination steel sheet pile - Google Patents

Description

  The present invention relates to a combination steel sheet pile, a retaining wall constituted by the combination steel sheet pile, and a method for selecting the combination steel sheet pile. The combined steel sheet pile and retaining wall of the present invention are used mainly for preventing collapse of earth and sand in harbor quay facilities, landfill revetments, underground excavation work and the like.

  In the field of civil engineering and construction, steel sheet piles are generally used as steel materials for underground continuous walls used mainly for retaining walls that prevent collapse of earth and sand and riverwalls. As the steel sheet pile, for example, a steel sheet pile of U shape, Z shape, straight line shape, hat shape or the like is used. In civil engineering construction work, an integral underground continuous wall (wall body) is formed by embedding the steel sheet pile joints in the soil while fitting them together. Here, as a general method for increasing the proof stress of the wall, a method of increasing the cross-sectional performance by increasing the cross-sectional size of the steel sheet pile alone, a steel sheet pile such as U-shaped, Z-shaped, linear, hat-shaped, etc. On the other hand, there is a method of using a combined steel sheet pile in which H-shaped steel or CT steel is joined by welding or the like.

  As related technologies, for example, Patent Documents 1 and 2 disclose underground continuous walls using a combination steel sheet pile. In the techniques disclosed in these Patent Documents 1 and 2, a web portion, a pair of flange portions provided continuously at both ends of the web portion, and a pair of arm portions provided continuously at the ends of the pair of flange portions. And a hat-shaped steel sheet pile having a joint portion formed at the ends of the pair of arm portions. And H-section steel is combined with this hat-shaped steel sheet pile. The H-shaped steel has a central web portion and a pair of flange portions (first flange portion and second flange portion) provided at both ends of the central web portion. Specifically, the hat-shaped steel sheet pile and the H-shaped steel are combined by fixing the second flange portion of the H-shaped steel to the outer surface of the web portion of the hat-shaped steel sheet pile by welding or the like. . In addition, in this invention, the arm part side (cross-sectional recessed part side) in a hat-shaped steel sheet pile is defined as an inner side, and the web part side (cross-sectional convex part side) is defined as an outer side.

  In particular, this combined steel sheet pile has a large bending rigidity with respect to a bending external force applied in a direction perpendicular to the length direction (embedding direction). Therefore, the combination steel sheet pile has been frequently used as a water blocking wall or a self-supporting earth retaining wall in the past.

JP 2002-212943 A International Publication WO2008 / 029835

  In general, since the water blocking wall is required to have bending rigidity only at the time of embedding, there is almost no case where the cross-sectional shape of the water blocking wall is determined based on the generated stress of the steel material after embedding. For this reason, it was not necessary to use the steel sheet pile and H-section steel with a high yield point in the water stop wall formed from a combination steel sheet pile.

  In the self-supporting earth retaining wall, the cross-sectional shape is determined according to the displacement of the earth retaining wall head, and the cross-sectional shape is not determined according to the bending moment generated by earth pressure or water pressure. For this reason, it was not necessary to use a steel sheet pile or H-section steel with a high yield point in the self-supporting earth retaining wall made of a combined steel sheet pile.

Table 1 shows the minimum yield points σ _yS and σ _yh of the hat-shaped steel sheet pile and the H-shaped steel sheet pile, and the yield by the combination of the combined steel sheet piles with the hat-shaped steel sheet pile (SYW295) and H-shaped steel (SM490A). The point ratio σ _yh / σ _ys is shown. Further, regarding the H-shaped steel, the minimum yield point and the minimum yield point ratio are compared by distinguishing the flange thickness between 16 mm or less and more than 16 mm. The H-shaped steel and the hat-shaped steel sheet pile are composed of materials having substantially the same level of strength. The minimum yield point of the SM490A H-section steel is 315 to 325 N / mm ² , and the minimum yield point of the SYW295 hat-shaped steel sheet pile is 295 N / mm ² . The yield point ratio σ _yh / σ _ys determined by classifying whether the flange thickness of the H-section steel exceeds 16 mm is 1.102 when the flange thickness of the H-section steel is 16 mm or less, and over 16 mm, It can be seen from Table 1 that it is 1.068. From these data, it can be seen that the yield point ratio σ _yh / σ _ys is at most about 1.1 regardless of the flange thickness of the H-section steel.

  However, the combination steel sheet pile is used not only for a self-supporting earth retaining wall but also for a retaining earth retaining wall used for a large harbor structure or the like. The reserved earth retaining wall is fixed by, for example, pulling the vicinity of the head of the connected steel sheet pile and the H-shaped steel with a tensile material such as a tie rod. However, the hat-shaped steel sheet pile as a steel sheet pile constituting the reserving earth retaining wall could not exert a significant advantage over the hot-rolled Z-shaped steel sheet pile.

Table 2 shows a comparison result example of the section modulus and the steel material weight when the necessary section modulus per quay is about 4000 cm ³ . In the example of the combined steel sheet pile in Table 2, a 10H hat-shaped steel sheet pile and a length of 700 mm from the bottom surface of the lower flange to the top surface of the upper flange, a flange width of 200 mm, a center web thickness of 9 mm, and a flange thickness of 12 mm Combined with shape steel. As a comparative example, a hot-rolled Z-type steel sheet pile is mentioned. From Table 2, it can be seen that the combined steel sheet pile satisfies the necessary section modulus (= 4000 cm ³ ) substantially the same as that of the Z-type steel sheet pile, and the steel material weight is not significantly different. However, since the combined steel sheet pile needs to fix the hat-shaped steel sheet pile and the H-shaped steel to each other by welding or the like, the processing cost increases. Therefore, a remarkable advantage cannot be exhibited as compared with the Z-shaped steel sheet pile.

  Therefore, the present invention has been devised in view of the above-described problems. The object of the present invention is to significantly improve the bending strength of the combined steel sheet piles of hat-shaped steel sheet piles and H-shaped steels (especially in the case of using for a retaining earth retaining wall), while maintaining the required section modulus. Combination steel sheet pile capable of reducing the weight of the steel sheet and exhibiting a significant advantage compared with conventional Z-shaped steel sheet piles, and earth retaining walls configured by connecting such combination steel sheet piles Is to provide.

The present invention uses the following means in order to solve the above problems.
(1) The first aspect of the present invention is a combined steel sheet pile having a hat-shaped steel sheet pile and an H-shaped steel. The hat-shaped steel sheet pile includes: a web portion; a pair of flange portions provided at both ends of the web portion; a pair of arm portions respectively provided at end portions of the pair of flange portions; It is a 10H type | mold hat-shaped steel sheet pile which has a pair of joint part each formed in an edge part. The H-shaped steel sheet pile includes a central web portion; a first flange portion provided at one end of the central web portion; and a second flange portion provided at the other end of the central web portion. The second flange portion is fixed to the outside of the web portion of the hat-shaped steel sheet pile, and has a ratio of a minimum yield point σ _yh of the H-shaped steel and a minimum yield point σ _ys of the hat-shaped steel sheet pile. A certain minimum yield point ratio σ _yh / σ _ys is 1.109 or more and 1.559 or less.

( 2 ) A second aspect of the present invention is a retaining wall using two or more combined steel sheet piles according to (1) above. In the earth retaining wall, the joint portions of the adjacent combined steel sheet piles are connected to each other.

(3) A third aspect of the present invention is a method for selecting a combination steel sheet pile having a hat-shaped steel sheet pile and an H-section steel. In this selection method, the hat-shaped steel sheet pile is a 10H type hat-shaped steel sheet pile, and the minimum yield which is the ratio of the minimum yield point σ _yh of the H-shaped steel and the minimum yield point σ _ys of the hat-shaped steel sheet pile. The combination is selected so that the point ratio σ _yh / σ _ys is 1.109 to 1.559.

According to the configuration described in (1) and (3) above, the hat-shaped steel sheet pile is a 10H-type hat-shaped steel sheet pile, the minimum yield point of the H-shaped steel in the combined steel sheet pile is σ _yh , and the hat-shaped steel sheet pile When the minimum yield point of σ _ys is σ _ys , the ratio σ _yh / σ _{ys is set} to 1.109 or more and 1.559 or less, so that the bending strength of the combined steel sheet pile can be increased more reliably and firmly. Is possible.
According to the structure as described in said (2), the earth retaining wall by the combined steel sheet pile which strengthened bending strength more can be obtained.
As described above, according to the present invention, it is possible to exert a remarkable advantage as compared with the conventional Z-shaped steel sheet pile by reducing the weight when satisfying the required section modulus.

It is a front view of the combination steel sheet pile which concerns on one Embodiment of this invention. It is a perspective view of the combination steel sheet pile. It is a side view of the combination steel sheet pile. It is a front view of the underground continuous wall body comprised by connecting two or more combination steel sheet piles which concern on one Embodiment of this invention. It is a perspective view of the underground continuous wall body. It is a figure which shows the value of y / H of 194 types of combination steel sheet piles.

In order to solve the above-described problems, the present inventors have focused on the fact that the bending strength of the combined steel sheet pile is dominated by the material of the H-shaped steel rather than the material of the hat-shaped steel sheet pile. The H-shaped steel and the hat-shaped steel sheet pile are fixed to each other by welding or the like to form a combined steel sheet pile. Therefore, the materials of the H-shaped steel and the hat-shaped steel sheet pile can be selected independently. That is, based on the characteristics of the material of the H-shaped steel and the hat-shaped steel sheet pile, the combination of the minimum yield point σ _yh of the H-shaped steel and the minimum yield point σ _ys of the hat-shaped steel sheet pile, and the ratio σ _yh / σ _ys can be arbitrarily selected. Therefore, the present inventors have found that a large bending strength can be obtained by setting the minimum yield point σ _yh of the H-section steel to be larger than the minimum yield point σ _ys of the hat-shaped steel sheet pile. Moreover, the present inventors set the length from the bottom surface of the arm part in the hat-shaped steel sheet pile to the top surface of the first flange part in the H-section steel, and from the bottom surface of the arm part to the neutral axis in the combined steel sheet pile. It has been found that when the length is y, the value of the ratio y / H does not reach 0.5, but is preferably about 0.475 at most as described later. The present inventors generally used a 10H-type hat-shaped steel sheet pile (width 900 mm, height 230 mm, cross-sectional area 110 cm ² / piece, cross-sectional secondary moment 9430 cm ⁴ / piece) or 25H-type hat-type steel sheet pile. About 194 kinds of combination steel sheet piles (width 900 mm, height 300 mm, cross-sectional area 144.4 cm ² / piece, cross-section secondary moment 22000 cm ⁴ / piece) and H-shaped steel having a height in the range of 400 mm to 1000 mm, The value of the ratio y / H was investigated. As for the H-section steel used for the combination, a special H-section steel having a flange thickness exceeding 30 mm as used for a column material was excluded. Steel sheet piles and H-shaped steels have a so-called plate thickness width ratio (t / d) value in order to exhibit predetermined cross-sectional performance. Therefore, y / H of the combined steel sheet pile is also distributed within a certain range. As shown in FIG. 6, the value of y / H of the combined steel sheet pile in the above range was about 0.37 for the lower limit and about 0.48 for the upper limit. A combination steel sheet pile close to the upper limit allows a more economical combination steel sheet pile selection with other combination steel sheet piles in an actual design. For example, a combined steel sheet pile of a 10H type steel sheet pile having a height of 450 mm, a flange width of 250 mm, and a flange thickness of 28 mm, having a y / H value of 0.48, has a cross-sectional modulus of 5050 cm ³ / m, a steel material weight of 266 kg / A combination sheet pile of a 10H type steel sheet pile and a H-section steel having a height of 500 mm, a flange width of 250 mm, and a flange thickness of 25 mm, which has a cm ² but has a section factor of 5186 cm ³ / m and a steel material weight of 253 kg / m. Can be substituted. The y / H value of the combined steel sheet pile in this case is 0.467. However, it is desirable to secure a wider combination of H-shaped steels in view of productivity and availability. The inventors determined that the upper limit value of y / H is desirably set to 0.475, which is close to the upper limit of the analysis result. This is because by setting this value, the value of y / H is brought close to the upper limit value, and the characteristics inherent to the combined steel sheet pile can be sufficiently exhibited. Since the value of y / H of the combined steel sheet pile is 0.475 or less, the length (H−y) from the neutral axis to the upper surface of the first flange portion of the H-section steel in the combined steel sheet pile and y The ratio is greater than 1 (Hy) / y is 1.105 or more. For this reason, the bending strength is determined by the edge stress of the H-section steel.

On the other hand, in selecting the combined cross section of the H-shaped steel and the hat-shaped steel sheet pile, from the viewpoint of not yielding the stress at the end of the cross section due to bending, the upper surface of the first flange portion in the H-shaped steel from the neutral shaft in the combined steel sheet pile The cross-sectional shape should be selected so that the ratio ( _Hy ) / y of the length (Hy) to y is equal to or greater than the above σ _yh / σ _ys , but (Hy) It is unnecessary to select a range in which / y is much larger than the above-mentioned σ _yh / σ _ys , and in this case, an unnecessary steel material strength is selected. In this case, (H−y) / y and the above σ _yh / σ By selecting a region that is almost equal to _ys , the stress generated at the outer edge of the hat-shaped steel sheet pile is less than the minimum yield point of the hat-shaped steel sheet pile at the minimum yield strength during the bending moment action that yields the outer edge of the H-shaped steel. Can be suppressed. Therefore, it can be set as the cross-sectional structure of an efficient combination steel sheet pile.

The point that should be selected is a combination of σ _yh and σ _ys that generally satisfies (H−y) / y = σ _yh / σ _ys while satisfying this relationship (H−y) / y ≧ σ _yh / σ _ys. considering, replacing the (H-y) a /y≧1.105 becomes limited, sigma _yh / sigma is limited according to the material properties of _ys σ _yh / σ _ys ≧ 1.105 according to the cross-sectional shape, material properties The inventors have found that the design guideline for the combined steel sheet pile can be obtained only by the above. According to this design guideline, by setting the yield ratio σ _yh / σ _ys to 1.105 or more, it is possible to provide a combined steel sheet pile in which the steel weight is greatly reduced for the same acting bending moment. .

  Hereinafter, as a preferred embodiment of the present invention, a combined steel sheet pile 1 applied to a retaining wall or the like will be described in detail.

  FIG. 1 is a front view of a combined steel sheet pile 1 according to an embodiment of the present invention, FIG. 2 is a perspective view thereof, and FIG. 3 is a side view thereof.

  The combined steel sheet pile 1 has a hat-shaped steel sheet pile 10 and an H-shaped steel 20.

  The hat-shaped steel sheet pile 10 includes a web part 11, a pair of flange parts 12, a pair of arm parts 13, and a pair of joint parts 14. The pair of flange portions 12 are continuously provided so as to be inclined from both sides of the web portion 11. Further, the pair of arm portions 13 are connected in parallel to the web portion 11 from the front end of the flange portion 12. The pair of joint portions 14 are respectively formed at the distal end portion of the arm portion 13. Of the pair of joint parts 14, one joint part 14 and the other joint part 14 have a point-symmetric cross-sectional shape. This joint portion 14 has a shape that can be fitted to another joint portion 14 in another adjacent combined steel sheet pile 1 and has a fitting strength so that the joint portions 14 do not detach from each other particularly during fitting. Has been enhanced.

  The hat-shaped steel sheet pile 10 used in the present invention is a rolled steel material obtained by hot rolling, and the joint portion 14 is formed into a complicated shape, and the strength of the joint portion 14 is increased.

  The H-section steel 20 is manufactured by rolling. The H-section steel 20 includes a central web portion 21 and a pair of flange portions 22a (first flange portions) and 22b (second lower flange portions) provided at both ends of the central web portion 21. One flange portion 22 b (second flange portion) in the H-shaped steel 20 is fixed to the outer surface of the web portion 11 in the hat-shaped steel sheet pile 10. The flange portion 22b (second flange portion) of the H-shaped steel 20 is fixed to the web portion 11 of the hat-shaped steel sheet pile 10 by, for example, welding, bonding, bolts, rivets, screws, scissors or the like. May be. Incidentally, in the following description, an example in which the welded portion 27 is fixed to the second flange portion 22b by welding will be described. As shown in FIG. 3, the welded portion 27 may be intermittently welded at an arbitrary interval toward the length direction (embedding direction) of the H-section steel 20 or may be continuously welded. . By welding in this manner, the hat-shaped steel sheet pile 10 and the H-shaped steel 20 can be fixed easily and firmly.

  In the combination steel sheet pile 1 described above, the H-shaped steel 20 is fixed to the hat-shaped steel sheet pile 10 to form an integral structure, and the second flange portion 22b of the H-shaped steel 20 is replaced with the hat-shaped steel sheet pile 10. It is desirable to make surface contact with the outer surface of the web part 11. The reason is that when the combined steel sheet pile 1 receives external force such as water pressure by bringing the second flange portion 22b into surface contact with the outer surface of the web portion 11 of the hat-shaped steel sheet pile 10, the hat-shaped steel sheet pile. This is because 10 and the H-section steel 20 share the force with each other and can behave as an integral structure. Furthermore, when the hat-shaped steel sheet pile 10 and the H-shaped steel 20 are welded to each other, the H-shaped steel 20 can be stabilized, and the welding work can be easily advanced.

  4 and 5 show an example in which the underground continuous wall body 5 is configured by connecting the combined steel sheet piles 1 having such a configuration to each other. The underground continuous wall body 5 is connected to each other through a joint portion 14 in each combination steel sheet pile 1 to constitute one wall body. Moreover, this underground continuous wall 5 is comprised by arrange | positioning the same combination steel sheet pile 1 continuously.

Next, the detailed configuration of the combined steel sheet pile 1 according to the present embodiment will be further described. In the combined steel sheet pile 1 according to the present embodiment, when the minimum yield point of the H-section steel 20 is σ _yh and the minimum yield point of the hat-shaped steel sheet pile 10 is σ _ys , these ratios σ _yh / σ _ys are 1.105 or more is set.

When this σ _yh / σ _ys is less than 1.105, the bending strength in the combined steel sheet pile cannot be sufficiently improved. Therefore, in order to secure a desired section modulus, the total weight of the steel material must be increased by increasing the cross-sectional area of the steel material. Therefore, when σ _yh / σ _ys is less than 1.105, it is disadvantageous because the machining cost is higher than that of the conventional Z-shaped steel sheet pile. On the other hand, in the combined steel sheet pile 1 according to the present embodiment, the material of the hat-shaped steel sheet pile 10 and the material of the H-section steel 20 are selected so that σ _yh / σ _ys is 1.105 or more as described above. Therefore, it is possible to further improve the bending strength of the combined steel sheet pile, and it is possible to exert superiority particularly when this is used for a reserved earth retaining wall.

The upper limit of σ _yh / σ _ys is not particularly specified, but may be about 1.6 which is the upper limit of the ratio of the minimum yield point of the hat-shaped steel sheet pile and the H-shaped steel of the current standard. Incidentally, even when there is no steel material standard, it is possible to produce a high yield point H-section steel, so that σ _yh / σ _ys may be configured to be 1.6 or more.

In particular, in the present invention, the ratio σ _yh / σ _ys between the minimum yield point σ _yh of the H-section steel and the minimum yield point σ _ys of the steel sheet pile is 1.109 to 1.559 as described later. It may be adjusted. Thereby, it becomes possible to implement | achieve the reinforcement | strengthening of the bending strength in the combination steel sheet pile 1 more reliably and firmly.

Hereinafter, with reference to FIG. 1, the dimension of the combination steel sheet pile 1 concerning this embodiment is demonstrated. As shown in FIG. 1, the length from the bottom surface of the arm portion 13 in the hat-shaped steel sheet pile 10 to the top surface of the first flange portion 22a in the H-shaped steel is H. Moreover, the length from the bottom face of the arm part 13 to the neutral axis in the combined steel sheet pile 1 is set to y. At this time, the ratio of the length (Hy) from the neutral shaft in the combined steel sheet pile 1 to the upper surface of the first flange portion 22a in the H-section steel 20 and y is expressed as (Hy) / y. The The cross-sectional shape may be selected so that this ratio (H−y) / y is larger than σ _yh / σ _ys . By determining the shapes of the hat-shaped steel sheet pile 10 and the H-shaped steel 20 so that the ratio ( _Hy ) / y is larger than σ _yh / σ _ys , the outer edge of the first flange portion 22 a in the H-shaped steel 20 When a bending moment that generates a stress corresponding to the minimum yield point σ _yh of the H-section steel 20 acts on the steel sheet pile 20, the stress generated at the outer edge of the hat-shaped steel sheet pile 10 is suppressed below the minimum yield point σ _ys of the steel sheet pile. It becomes possible to act. Thereby, the bending strength in the combined steel sheet pile 1 can be further increased. As a result, it is possible to further reduce the weight when satisfying the required section modulus, and it is possible to exert a significant advantage as compared with the conventional Z-shaped steel sheet pile.

Hereinafter, the combination of the combination steel sheet pile 1 which concerns on one Embodiment of this invention is demonstrated in detail. Hereinafter, combinations in which the ratio σ _yh / σ _ys between the minimum yield point σ _yh of the H-section steel and the minimum yield point σ _ys of the hat-shaped steel sheet pile will be 1.105 or more will be described.

  Table 3 shows examples of combinations of the hat-shaped steel sheet pile 10 and the H-shaped steel 20 of the combined steel sheet pile 1.

In the combination example in Table 3, JIS 5523 SYW295 is used for the hat-shaped steel sheet pile 10. This SYW295 has a minimum yield point of 295 N / mm ² . Moreover, in the combination example in Table 3, Q345B of Chinese standard GB / T1591, SM490YA of JISG3106, and SM570 of JISG3106 are used for the H-section steel 20, respectively. The minimum yield points σ _yh and σ _ys of the H-section steel 20 and the hat-shaped steel sheet pile 10 are shown in the table, respectively. From Table 1, when Q345B is used as the standard of the H-section steel 20, σ _yh / σ _ys is 1.169. When SM490YA is used as the standard of the H-section steel 20, σ _yh / sigma _ys is 1.203, in the case of using the SM570 as standard H-beams 20, sigma _yh / sigma _ys is found to be 1.559.

  Table 4 shows another combination example of the hat-shaped steel sheet pile 10 and the H-shaped steel 20 of the combined steel sheet pile 1.

In Table 4, S320GP of Euro standard EN10248 is used as the standard of the hat-shaped steel sheet pile 10. This Euro standard EN10248 S320GP has a minimum yield point of 320 N / mm ² . Moreover, SM490YA and SM570 are used for the H-section steel 20 as examples. Table 4 shows the minimum yield points σ _yh and σ _ys of the H-section steel 20 and the hat-shaped steel sheet pile 10, respectively. From Table 4, when SM490YA is used as the standard of the H-section steel 20, σ _yh / σ _ys is 1.109, and when SM570 is used as the standard of the H-section steel 20, σ _yh / σ _It can be seen that _ys is 1.438.

Thus, by using the hat-shaped steel sheet pile 10 and the H-shaped steel 20 having the standards shown in Tables 3 and 4, σ _yh / σ _ys can be set to about 1.109 to 1.559, and the combination The bending strength in the steel sheet pile 1 can be increased. Of course, since there are various steel standards other than these standards, the hat-shaped steel sheet pile 10 and the H-section steel 20 are arbitrarily selected within the range where the minimum yield point ratio σ _yh / σ _{ys of} the combined steel sheet pile 1 is 1.105 or more. And may be combined.

In the following description, the ratio ( _Hy ) / y of the length (Hy) to y from the neutral axis of the combined steel sheet pile to the upper surface of the first flange portion 22a of the H-section steel is σ _yh. A cross-sectional shape selected to be larger than / σ _ys will be described.
Based on the dimensions of the hat-shaped steel sheet pile 10 and the H-shaped steel 20 shown in FIG. Can be sought.
y = {(As · hs / 2) + (2 · Ah · hs + Ah · h _h ) / 2} / (As + Ah) (1)

here,
hs: height of the hat-shaped steel sheet pile 10 (see FIG. 1)
h _h : Height of H-section steel 20 (see FIG. 1)
As: Cross-sectional area per piece of hat-shaped steel sheet pile 10 Ah: Cross-sectional area per piece of H-section steel 20

Further, y / H can be calculated based on the following equation (2).
y / H = {hs / H + (Ah / As) / (1+ (Ah / As))} / 2 (2)

Further, the ratio (Hy) / H of the length (Hy) from the neutral shaft to the upper surface of the first flange portion 22a of the H-section steel 20 in the combined steel sheet pile 1 is (1- (Y / H)), and the ratio of the length y from the neutral axis in the combined steel sheet pile 1 to the bottom surface of the arm portion 13 in the hat-shaped steel sheet pile 10 is represented by y / H. . When the ratio (1- (y / H)) / (y / H) is equal to or greater than the minimum yield point ratio σ _yh / σ _ys , the following expression (3) is obtained.
(1- (y / H)) / (y / H) ≧ σ _yh / σ _ys (3)

In this formula (3), the ratio of the length from the neutral shaft to the top surface of the first flange portion 22a of the H-section steel 20 and the length from the neutral shaft to the bottom surface of the arm portion 13 in the hat-shaped steel sheet pile 10 is the smallest. It indicates that the yield point ratio is σ _yh / σ _ys or more.

When the value of the expression (2) is substituted into the expression (3) and developed, the following expression (4) is obtained.
(2-((hs / H) + (Ah / As) / (1+ (Ah / As))) / ((hs / H) + (Ah / As) / (1+ (Ah / As)) ≧ σ _yh / Σ _ys (4)

Here, by _setting σ _yh / σ _ys = β and solving for Ah / As, the following equation (5) can be derived.
Ah / As ≦ (2- (1 + β) · (hs / H)) / (β + (1 + β) · (hs / H) -1) (5)

  That is, the ratio Ah / As of the cross-sectional area As of the H-section steel 20 applied to the combined steel sheet pile 1 and the cross-sectional area As of the hat-shaped steel sheet pile 10 is determined based on each parameter defined in the equation (5). Can do.

That is, in the combined steel sheet pile 1, the height of the hat-shaped steel sheet pile 10 and the H-shaped steel 20 is assumed, and the yield point of the hat-shaped steel sheet pile 10 and the H-shaped steel 20 is assumed. The ratio (hs / H) between the height (hs) of the steel sheet and the height (H) of the combined steel sheet pile 1 and the ratio β (= σ _yh / σ _ys ) of the yield point of the H-section steel 20 and the hat-shaped steel sheet pile 10 ) Is decided. Therefore, it is possible to set a reasonable cross-sectional shape from the combination (Ah / As) of the cross sections of the hat-shaped steel sheet pile 10 and the H-shaped steel 20 that satisfy Expression (5).

That is, by selecting a combination of the hat-shaped steel sheet pile 10 and the H-shaped steel 20 so as to satisfy the formula (5), the upper surface of the first flange portion 22a in the H-shaped steel 20 from the neutral shaft in the combined steel sheet pile 1 Each cross-sectional shape is selected so that the length ratio (H−y) / y is larger than the yield ratio β (= σ _yh / σ _ys ) of the H-section steel 20 and the hat-shaped steel sheet pile 10. it can. As a result, when a bending moment that generates a stress corresponding to the minimum yield point σ _yh of the H-section steel 20 acts on the outer edge of the first flange portion 22a of the H-section steel on the wall body of the combined steel sheet pile 1 as a result. Furthermore, the generated stress at the outer edge of the hat-shaped steel sheet pile 10 can be suppressed below the minimum yield point of the hat-shaped steel sheet pile 10 itself, and the cross-sectional shape of the combined steel sheet pile 1 is effective in enhancing the bending strength. It becomes possible.

  Next, an approach method for selecting the cross-sectional shape of the combined steel sheet pile 1 will be described. Table 5 shows cross-sectional data of the hat-shaped steel sheet pile 10 used for explaining this approach method, and Table 6 shows cross-sectional data of the H-section steel 20.

  As the hat-shaped steel sheet pile 10, a 10H hat-shaped steel sheet pile 10 shown in Table 5 is used. The width, height, cross-sectional area As, cross-sectional secondary moment Is, and steel weight of the 10H hat-shaped steel sheet pile 10 are as shown in Table 5. Moreover, seven types of H-section steel 20 having different cross-sectional areas Ah were prepared. Each size, cross-sectional area Ah, cross-sectional secondary moment Ih, and steel material weight are as shown in Table 6.

  Table 7 shows a list of the combined steel sheet piles 1 configured by combining each type of H-section steel 20 shown in Table 6 with respect to the hat-shaped steel sheet pile 10 shown in Table 5.

The combination numbers in Table 7 correspond to the combination numbers of the H-section steel 20 shown in Table 5. For example, in the combination number 1 in Table 7, the combined steel sheet pile 1 is configured by combining the H-section steel 20 corresponding to the combination number 1 in Table 6 and the hat-shaped steel sheet pile 10 shown in Table 5. . Incidentally, in Table 7, for each combination number, the ratio Ah / As between the cross-sectional area As of the H-section steel 20 and the cross-section As of the hat-shaped steel sheet pile 10, the height (hs) of the hat-shaped steel sheet pile 10, and Ratio hs / H with the height (H) of the combined steel sheet pile 1, ratio y / H between the length y from the bottom surface of the arm 13 to the neutral axis of the combined steel sheet pile 1 and the height H of the combined steel sheet pile 1 Furthermore, each parameter of (1- (y / H)) / (y / H) is shown. Further, the section modulus Z (cm ³ ) per sheet pile determined by the edge stress of the H-shaped steel 20 of the combined steel sheet pile 1, the steel material weight w (kg / piece) per one of the combined steel sheet piles, Stress σ _s (N / mm) generated at the outer edge of the steel sheet pile 10 when a stress corresponding to the minimum yield point of the H-section steel is applied to the outer edge of the H-section steel 20 (outer edge of the first flange 22a). ² ) is shown.

The generated stress is generally proportional to the distance from the neutral axis within the elastic range. Therefore, the stress σ _s generated at the outer edge of the steel sheet pile 10 is the ratio of the stress σ _h generated at the outer edge of the first flange 22a of the H-section steel and the distance of the neutral axis (1- (y / H)) / ( y / H) can be calculated using the following formula. It is assumed that this equation can be applied even when the stress σ _s generated at the outer edge of the steel sheet pile 10 exceeds the yield point.

Note that the stress σ _h generated at the outer edge of the H-shaped steel flange 22a assumes that the minimum yield point σ _yh of the H-shaped steel acts, so σ _h = σ _yh .
σ _h : σ _s = (H−y): y = (1− (y / H)) :( y / H)
σ _s = σ _h / ((1- (y / H)) / (y / H))

Table 8 shows the minimum yield point and the minimum yield point ratio of the H-section steel 20 and the hat-shaped steel sheet pile 10 combined in Table 7. The minimum yield point is 355 (N / mm ² ) for H-section steel 20 and 295 (N / mm ² ) for hat-shaped steel sheet pile 10. Further, the yield point ratio (σ _yh / σ _ys ) is 1.20.

Further, Table 9 shows a ratio Ah / As of the cross-sectional area Ah of the H-section steel 20 and the cross-sectional area As of the hat-shaped steel sheet pile 10 obtained by the equation (5). Table 8 shows that hs / H is 0.247 and the yield point ratio σ _yh / σ _ys is 1.20, indicating that the area ratio Ah / As is 1.96. Yes.

In order to actually select the cross-sectional shape of the combined steel sheet pile 1, the ratio (1- (y / H) can be selected by selecting a combined cross-section from which the Ah / As is 1.96 or less from the equation (5) and Table 9. )) / (Y / H) can be selected so that the minimum yield point ratio σ _yh / σ _{ys is} greater than or equal to. For this reason, even when the stress corresponding to the minimum yield point of H-section steel acts with respect to the outer edge of H-section steel 20 by setting it as the cross-sectional shape of the combination numbers 1-4 mentioned in Table 7, of steel sheet pile 10 Any stress σ _s generated at the outer edge can be suppressed to the minimum yield point (295 N / mm ² ) or less of the hat-shaped steel sheet pile 10. Actually, as shown in Table 7, the stress sigma _s occurring in the outer edge of the calculated sheet pile 10, the combination number 1 213N / mm ^2, a combination number 2 228N / mm ^2, the combination number 3 239N / mm ² The combination number 4 is 270 N / mm ² , and is shown to be suppressed to the minimum yield point (295 N / mm ² ) or less of the hat-shaped steel sheet pile 10. As a result, it can be seen that the cross-sectional shape of the combined steel sheet pile 1 can be made more effective in enhancing the bending strength.

However, in the combination numbers 5 to 7, the ratios Ah / As are 2.10, 2.21, and 2.37, respectively, exceeding 1.96 calculated from the equation (5). As for the stress sigma _s occurring in the outer edge of the sheet pile 10, the combination number 5 305N / mm ^2, the combination number 6 313n / mm ^2, the combination number 7 and 321N / mm ^2, both the hat-shaped steel sheet pile 10 minimum yield point (295 N / mm ² ) is exceeded. Therefore, although the yield point of H-section steel 10 is improved compared with the yield point of hat-shaped steel sheet pile 20, the advantage cannot be enjoyed. As a result, in order to make the minimum yield point (295 N / mm ² ) or less of the hat-shaped steel sheet pile 10, it is necessary to reduce the section modulus. In the said Example, in order to demonstrate the approach method for selecting the cross-sectional shape of the combination steel sheet pile 1, the 10H-shaped hat-shaped steel sheet pile shown in Table 5 was mentioned as an example. The steel sheet pile used for the combined steel sheet pile 1 may be a hat-shaped steel sheet pile other than this. For example, a 25H-shaped hat-shaped steel sheet pile having a width of 900 mm, a height of 300 mm, a cross-sectional area of 144.4 cm ² / line, and a cross-sectional secondary moment of 22000 cm ⁴ / line may be used.

  Table 10 shows the steel material weight reduction effect of the conventional example and the present invention example when the required yield bending moment is 1450 kN · m / piece.

In the conventional example, the minimum yield point of the hat-shaped steel sheet pile 10 is 295 N / mm ² , and the minimum yield point of the H-section steel 20 is 315 N / mm ² . In order to satisfy the required yield bending moment of 1450 kN · m / piece, the conventional example requires a steel weight of 195 kg / piece, whereas in the example of the present invention, it can be achieved with a steel weight of 186 kg / piece. The inventive example can achieve a weight reduction of about 5% compared to the conventional example.

  Table 11 shows the steel material weight reduction effect of the conventional example and the present invention example when the required yield bending moment is 1490 kN · m / piece. In order to satisfy the required yield bending moment of 1490 kN · m / piece, the conventional example requires a steel weight of 225 kg / piece, whereas in the example of the present invention, it can be achieved with a steel weight of 186 kg / piece. The example of the present invention can achieve a weight reduction of about 17% compared to the conventional example.

  According to the present invention, the bending strength of the combined steel sheet pile formed by combining the hat-shaped steel sheet pile and the H-shaped steel can be greatly improved, and the weight of the combined steel sheet pile can be reduced. Industrial applicability is great.

DESCRIPTION OF SYMBOLS 10 Hat-shaped steel sheet pile 11 Web part 12 Flange part 13 Arm part 14 Joint part 20 H-section steel 21 Central web part 22a 1st flange part 22b 2nd flange part 27 Welding location

Claims (3)

A combined steel sheet pile having a hat-shaped steel sheet pile and an H-shaped steel,
The hat-shaped steel sheet pile is
With the web part;
A pair of flange portions provided at both ends of the web portion;
A pair of arm portions respectively provided at end portions of the pair of flange portions;
A pair of joint portions respectively formed at end portions of the pair of arm portions;
Is a 10H type hat-shaped steel sheet pile to have a,
The H-shaped steel is
A central web section;
A first flange portion provided at one end of the central web portion;
A second flange portion provided at the other end of the central web portion;
Have
The second flange portion is fixed to the outside of the web portion of the hat-shaped steel sheet pile,
The minimum yield point ratio σ _yh / σ _ys , which is the ratio of the minimum yield point σ _yh of the H-shaped steel and the minimum yield point σ _ys of the hat-shaped steel sheet pile, is 1.109 or more and 1.559 or less. Combination steel sheet pile characterized by.   A retaining wall using two or more combined steel sheet piles according to claim 1, wherein the joint portions of the adjacent combined steel sheet piles are connected to each other. A combination selection method for a combination steel sheet pile having a hat-shaped steel sheet pile and an H-section steel,
The hat-shaped steel sheet pile is a 10H type hat-shaped steel sheet pile,
The minimum yield point ratio σ _yh / σ _ys , which is the ratio of the minimum yield point σ _yh of the H-shaped steel and the minimum yield point σ _ys of the hat-shaped steel sheet pile, is 1.109 or more and 1.559 or less. A combination steel sheet pile combination selection method characterized by selecting a combination.

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