JPS5833328B2 - Floating Kisokohou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a floating foundation construction method for constructing a structure on soft ground.

Conventionally, soil improvement methods for soft ground include replacement with high-quality soil, deep soil improvement, and foundation pile driving, but these methods are not preferred because they require large public safety costs for ground improvement. The inventor of the present invention conducted various research in an attempt to find a construction method that could eliminate this drawback, and found that if a lightweight cement-concrete plate with low water absorption and high strength is laid on soft ground. In addition to the load dispersion effect, apparent buoyancy acts, so it is possible to reduce the sinking of the lightweight foundation due to the load, and a water-resistant canvas with a width wider than the above-mentioned lightweight foundation was laid on soft ground. After that, if a lightweight body with the same properties as above is placed on top of it, in addition to the load reduction effect due to the buoyancy and load distribution of the lightweight body, the load-bearing capacity of the floating foundation can be further increased due to the load distribution of the campus. I found out.

The present invention is a method based on these findings, in which a water-resistant canvas is laid on soft ground, and a lightweight cement-concrete body with low water absorption, which is smaller than the width of the canvas, is cast in the form of a plate. This is a floating foundation construction method characterized by the construction of a floating foundation.

In the present invention, the plate-shaped lightweight body is made by appropriately mixing ordinary Portland cement or various mixed cements with foamed particles, sand, filament, etc., and has an air-dry specific gravity of 0.4~
1.5, an absorption amount of 10% (capacity) or more, a bending and shear strength of 5 to 20 μg, and a Young's modulus of 104 μg or more.

The foam particles may be foams of inorganic materials such as whitebait or synthetic resins, especially styrene resin foams with an apparent specific gravity of 0.
About 02 is used.

Further, as the water-resistant canvas, synthetic resin fibers such as nylon fibers and polyester fibers, which are strong and water-resistant, are used.

The width of the canvas should be wider than the width of the lightweight board.

If the width of the canvas bed is narrowed, the campus sharing force will increase, and the apparent overload will be reduced. Therefore, by reducing the width of the light board, the load-bearing capacity of the floating foundation will be improved, and it will be possible to prevent settlement. can also be reduced.

According to the present invention, if a floating foundation material is laid with specific gravity and strength determined according to the thickness of the soft layer of the soft ground and the type and load strength of the overlying structure, the underlying soft layer can be improved. In addition, there is no need to worry about placing a pile foundation, and the structure can be immediately constructed on the floating foundation material, which simplifies construction and greatly reduces construction costs.

Example: When building an embankment with a bottom width of 5 m and a height of 1 m, the embankment material (capacity 1
Flatten the surface of the sludge layer (adhesive y) with a surface solidity of 0-1"/71 (layer thickness H4, 10 m) to a thickness of about 20 to 50 crrL, such that the mountain soil of 5 t/s collapses. The following four types of tests were conducted on the ground.

Among these, test numbers 1 and 2 were conducted for comparative tests.

Test 1 A piece of nylon canvas (300g/m") was laid over the entire surface of the test section with a width of 1577L and a length of 20m, and an embankment with a bottom width of 5m was placed on top of this, and the ground was raised until it collapsed. Case test 2 Ordinary cement concrete (specific gravity 2.2t/m') was laid in a test area with a width of 10m and a length of 20m, with a width of 10m and a thickness of 2.
After pouring 0CIrL over the entire surface and allowing natural curing under conditions of daytime outside temperature (approximately 10 to 15°C) for 10 days, an embankment with a bottom width of 5 m was placed on top of this and the pile was raised until it failed. Test 3. In the same way as in 2, on a test with a bed width of 10 m x length of 20 m, a mixture of ordinary cement mortar and styrofoam foam particles (specific gravity 0.5) was poured over the entire surface of the bed with a bed width of 10 m and a bed thickness of 20 CrfL, and the test was carried out. After natural curing as in 2,
A test was carried out on top of this with a bottom width of 5rrL, and the embankment was built up to the point of failure.4 Similar to Test 2, one piece of nylon canvas, the same as that used in Test 1, was laid in a test section with a width of 15 m and a length of 20 m. A mortar with the same composition as the mortar used in Test 3 was poured over the entire surface with a width of 1077L and a thickness of 20crfL, and after natural curing in the same manner as Test 3, a bottom The results of the four tests described above are shown below when a 5 m wide embankment was built and the soil was raised to the point of failure.

Claims (1)

[Claims] 1.In addition to laying a water-resistant campus on soft ground,
A floating foundation construction method characterized in that a lightweight cement-concrete body with low water absorption, which is smaller than the laying width of the campus, is cast in the form of a plate.