JPH0351364Y2 - - Google Patents

Description

[Detailed explanation of the idea]

<<Industrial Application Field>> This invention relates to steel materials for reinforcing underground structures such as earth retaining walls and piles, which are buried in solidifying mud, and particularly relates to steel materials with enhanced frictional force. 《Problems with conventional technology》 As is well known, as a type of construction method for constructing earth retaining walls and piles in the soil, a hole is drilled in the ground using a digging machine such as an earth auger, and the hole is then filled with soil cement. There is a method of building H-shaped steel for reinforcement. This construction method produces less vibration and noise than the pile driving method, so it is used for construction work in urban areas or near existing buildings. In some cases, it was necessary to shorten the penetration length of earth retaining walls and piles in consideration of the economic efficiency of construction, such as in cases of deep construction. In this case, there was a problem in that the H-beams supporting temporary loads and traffic loads would wear out due to friction in the soil cement, making it impossible to obtain the vertical load necessary for retaining walls and piles. Therefore, a method has been proposed in which reinforcing bars are horizontally welded to the H-shaped steel to increase the frictional force. However, this method has the following problems. In other words, when an H-beam with fixed horizontal reinforcing bars is inserted into soil cement, breathing water from the soil cement collects on the bottom surface of the horizontal reinforcing bars, and when it hardens, the strength of this part decreases and vertical loads act on it. There was a problem that when this happened, this part was crushed and sufficient frictional force could not be expected. This invention was made in view of the above-mentioned problems, and its purpose is to provide a steel material for reinforcing underground structures that can provide sufficient friction even when the penetration length is shortened. It's about doing. 《Means for solving the problem》 In order to achieve the above purpose, this invention is used for reinforcing structures such as earth retaining walls and piles built in the soil, and The steel material has a pair of flanges disposed in parallel, a web disposed in a direction perpendicular to the flanges and integrally connecting the flanges, and a surface of the flanges and the web. It is characterized in that it is formed by fixing a plurality of linear ribs whose longitudinal axes and axes of the steel material intersect at a predetermined angle of inclination. <<Operation>> Since the ribs of the reinforcing steel material with the above structure are inclined with respect to the longitudinal axis of the steel material, breathing from the soil cement rises along the lower surface of the ribs, and when the soil cement hardens, The frictional force of the reinforcing steel material is reliably increased without causing any portions of reduced strength. <<Embodiments>> Hereinafter, preferred embodiments of this invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of the reinforcing steel material for underground structures according to this invention. The steel material 10 shown in the figure has a pair of flat flanges 12, 12 arranged in parallel.
It is an H-shaped steel having an H-shaped cross section integrally connected by a web 14 orthogonal to each flange 1.
Ribs 16 are fixed to the outer surfaces of 2 and 12 and to both sides of the web 14, respectively. The rib 16 is, for example, the flange 12, the web 1
4. Deformed reinforcing bars with approximately the same diameter as the thickness are used,
The steel material 10 is fixed at a plurality of locations by welding at appropriate intervals along the longitudinal direction. Further, each of the ribs 16 that are adjacent to each other in the longitudinal direction is inclined in different directions, and in this embodiment, the angle with respect to the horizontal is set to approximately 45 degrees, so that the axes of the ribs 16 are orthogonal to each other. It's summery. The steel material 10 having the above structure is built into the hole after drilling a hole in the ground and filling it with soil cement, and is used as a reinforcing member for earth retaining walls and piles. The amount of pile head displacement due to vertical load was tested using the model shown below. First, the steel material 10 of the present invention has a cross section of 100×100×
Four 100 x 8 mm deformed reinforcing bars were fixed to an 8 x 6 mm H-shaped steel with a length of 47 cm as ribs 16 by tilting them in a V-shape at an angle of about 45 degrees to the horizontal. The steel material 10 is prepared by filling a bottomed cylindrical body 18 with an open upper end with soil cement 20 mixed as shown in the table below, and then inserting the steel material 10 into the interior so that the tip protrudes by about 30 mm. A test specimen as shown in Figure 2 was produced. Two types of soil samples were used to mix in Soil Cement 20: Kanto loam soil (water content W approx. 55%) and alluvial clay (water content W approx. 60%).
A load was applied to the upper end of the pile, and the load-pile head displacement curve shown in Figure 3 was obtained.

[Table] All amounts of cement, etc. shown in the table are per ^1m3 . In this test, in order to compare with the steel material 10 of the present invention, a test specimen of a conventional example was also created using the method described above using an H-beam steel with the same dimensions and shape without ribs 16, and was tested under the same conditions. Based on the results shown in FIG. 3, FIG. 4 is a graph showing the rate of increase in the frictional force of the steel material 10 of the present invention, assuming that the frictional force of the untreated H-section steel is 1.0. As is clear from the test results shown in FIGS. 3 and 4, steel material 10 of the present invention showed a large increase in frictional force of 1.41 times in Kanto loam soil and 2.17 times in alluvial clay. When the test specimen was dismantled after the test, many soil cements 20 were found to have undergone shear failure in the expanded central portion between the ribs 16. Such shear failure is caused by the strong adhesive force between the soil cement 20 and the steel material 10. In other words, since the adjacent ribs 16 are inclined in different directions, when a load is applied, the ribs 16,
The soil cement 20 between the ribs 16, 16
A behavior occurs in which the soil cement 20 and the steel material 10
It is thought that shear failure is caused as a result of less peeling and complete prevention of peeling. <<Effects of the invention>> As explained above in detail in the Examples, according to the steel material for reinforcing underground structures according to the present invention, it is possible to greatly increase friction while eliminating the adverse effects of breathing caused by soil cement. Excellent effects such as

[Brief explanation of the drawing]

Fig. 1 shows an example of the steel material according to the present invention, Fig. A is a side view, Fig. B is a plan view, Fig. 2 is an explanatory diagram of the test specimen, and Fig. 3 is a load and pile cap. The graph of the amount of displacement, FIG. 4, is a graph showing the rate of increase in frictional force. 10... Steel material, 12... Flange, 14... Web, 16... Rib, 18... Bottomed cylinder, 20...
...soil cement.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A steel material that is used for reinforcing structures such as retaining walls and piles built in the soil and is buried in solidifying mud; , has a pair of flanges arranged in parallel, and a web arranged in a direction perpendicular to the flanges and integrally connecting the flanges, and has a longitudinal axis of the steel material on the surfaces of the flange and the web. 1. A steel material for reinforcing underground structures, comprising a plurality of fixed linear ribs whose axes intersect at a predetermined angle of inclination. (2) Claim 1 of the utility model registration claim, characterized in that the ribs are provided at intervals along the longitudinal direction of the steel material, and adjacent ribs are inclined in different directions. Steel materials for reinforcing underground structures.