JPH0634043U - Foundation material for soft ground - Google Patents

Abstract

(57) [Summary] [Purpose] To realize a low-cost negative friction reducing pile that does not use bitumen and has no problems such as dripping due to heat. [Structure] A special resin 2 that gradually decomposes and disappears in soil is applied to the surface of a steel pipe pile 1, and this is covered with a water-permeable sheet 3.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention is directed to PC piles, steel pipe piles, steel pipe sheet piles, PC piles that reduce the negative frictional force acting on the foundation of a building constructed on soft ground due to ground subsidence, that is, negative frictional force. The present invention relates to basic members such as sheet piles and steel sheet piles.

[0002]

[Prior art]

 When a building is built on a soft ground such as a seaside landfill or alluvial plain, various foundation members such as PC piles, steel pipe piles, steel pipe sheet piles, PC sheet piles, and steel sheet piles (hereinafter referred to as (Also referred to as pile body), a downward force, that is, a negative frictional force, causes the pile body to buckle or sink when it is severe, resulting in unequal settlement of the building on the foundation. To cause tilting or destruction.

As a means for reducing such a negative frictional force, a coating layer of asphalt bitumen (bitumen, hereinafter abbreviated as bitumen) is provided on the surface of the pile body. A bitumen suitable for this purpose is recommended to have a composition shown in the range specified by the softening point and the penetration by JP-B-53-21202 or JP-B-56-46012. ing.

A thickness is necessary for such a bitumen layer to exert a sliding effect, and it is usually applied to the surface of the pile body in a thickness of about 1.5 to 6 mm. However, if such piles are stored outdoors for a long period of time or transported in hot weather, the piles will become hot and the bitumen will soften, causing the phenomenon that the weight of the piles falls off the pile surface. Therefore, it took time to select and store in a cool shade and cool the bitumen with water. In addition, in some cases, the bitumen layer may partly peel off or be damaged due to handling during transportation or contact with surrounding objects during casting, and the original function may not be exhibited. For this reason, it has been proposed, for example, in JP-A-53-51607 to form a protective coating layer on the surface of the bitumen layer with a resin coating or the like.

[0005]

[Problems to be solved by the device]

 By the way, such a negative friction reducing pile is associated with a considerable cost increase due to the thick coating of bitumen of a specific composition on the surface, and by providing a resin protective layer on the surface, the production cost of the pile is increased. In addition to the ever-increasing number of bits, the bitumen layer is soft, so that the resin protective layer cannot completely prevent dripping and damage.

An object of the present invention is to solve such problems and to realize a novel foundation member for soft ground which does not use bitumen.

[0007]

[Means for Solving the Problems]

 The foundation member for soft ground of the present invention is characterized in that the surface of the pile body is coated with a special resin whose adhesive function is gradually lowered in the soil, and is covered with a water-permeable sheet.

[0008]

[Work]

 The present invention is constructed by applying a special resin to the surface of a pile used as a base member and coating it with a water-permeable sheet. The special resin deteriorates due to moisture or bacteria in the soil that has penetrated through the water-permeable sheet and gradually loses its adhesive function, and eventually loses its adhesive strength. Alternatively, it is gradually decomposed by water and bacteria in the soil and completely disappears within 2 to 6 months.

As a result, the pile body is in a state in which the contact with the surrounding soil is blocked by the water permeable sheet, and the residual resin or the void after the disappearance functions as a “sliding layer” and even if the surrounding strata sinks. The negative frictional force is greatly reduced without exerting any frictional force on the pile body.

[0010]

【Example】

 FIG. 1 is a perspective view of a negative friction reducing steel sheet pile which is an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a negative friction reducing steel pipe pile which is another embodiment of the present invention, in which 1 is a sheet pile or a steel pipe. Steel foundation members that are piles, 2 is a special resin layer, and 3 is a water-permeable sheet, both of which show the state of the product stage before being placed into the soil.

The special resin layer 2 is formed by coating the surface of the pile body with a special resin whose adhesive function is gradually lowered in the soil after the casting, by spraying or the like. At present, various types of such special resins are in the process of being developed. For example, polyester resins and polyester resins that gradually lose their adhesive strength by being deteriorated by moisture or bacteria in soil such as anaerobic soil fungus An adhesive or a synthetic rubber adhesive that gradually loses its adhesive force by being hydrolyzed by water in the soil or in water is preferable.

If the special resin itself does not have adhesiveness, a normal adhesive is applied to the steel material as a pretreatment, and then the special resin is applied. This special resin layer 2 has the purpose of separating the pile body from the surrounding soil, so if it is too thick, not only will it take time to apply it, but it will also be uneconomical, and it will take time to disassemble and disappear after placing it. Since there are obstacles such as required, it is usually desirable to keep the minimum necessary thickness of 1 mm or less.

On the other hand, the water-permeable sheet 3 is a kind of protective layer, but unlike the protective layer for the bitumen layer shown in the prior art example, the special resin layer 2 on the inner side has a thin thickness and bitumen. Since it is not a soft material like the one described above but a solidified resin, it does not need a protective function, and it is sufficient if it is firmly adhered to the pile body at the time of driving. Therefore, a porous polymer resin film, a non-woven fabric, a water permeable sheet for civil engineering, etc., that is permeable to air and water are preferable.

Although the case of steel sheet piles and steel pipe piles has been illustrated as an example, the above procedure does not change at all even if the pile body which is the material is a PC pile or a PC sheet pile. The foundation member for soft ground according to the present invention can be used not only as a foundation member for soft ground, but also because it separates its behavior in the event of an earthquake or subsidence, so it can also be widely used for sheet pile walls when edging the ground.

[0015]

[Effect of device]

 According to the present invention, not only is the manufacturing cost reduced as compared with the conventional negative friction reducing pile having a large amount of bitumen and a protective layer provided, but also handling such as transportation and storage is possible. It is easy to use and does not require watering, and the pile diameter is compact, so it has excellent workability and many other advantages.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of an embodiment of the present invention.

FIG. 2 is a sectional view showing a configuration of an embodiment of the present invention.

[Explanation of symbols]

 1 Steel sheet pile (steel pipe pile) 2 Special resin layer 3 Water permeable sheet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yugo Oka 2-3 2-3 Uchisaiwaicho, Chiyoda-ku, Tokyo Hibiya International Building, Kawasaki Steel Corporation Tokyo Headquarters (72) Shinji Kondo Hamamatsu, Minato-ku, Tokyo 2-16, Machi No.3 Kasuya Building Fuji Engineering Co., Ltd. Tokyo Branch

Claims (3)

[Scope of utility model registration request] 1. A base member for soft ground, characterized in that the base member is formed by coating a surface of the base member with a special resin whose adhesive function is gradually lowered in the soil, and coating this with a water-permeable sheet. 2. The foundation member for soft ground according to claim 1, wherein the special resin to be applied is a resin that is decomposed by anaerobic soil bacteria in the soil. 3. The foundation member for soft ground according to claim 1, wherein the special resin to be applied is a resin which is hydrolyzed by water in soil.