JPS62276101A - Frost heaving prevention or soft ground improvement method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for improving frost heaving or soft ground on roads, etc., and more specifically, the present invention relates to a method for improving frost heaving or soft ground on roads, etc. Concerning construction methods for laying roads, etc.

[Conventional technology]

Conventionally, there are over 20 methods for improving frost heaving or soft ground for roads, etc., including displacement, embankment, slow construction, vertical drain, sand compaction, quicklime pile, etc.

Even now, improvement of conventional construction methods and development of new construction methods are active, and frost heaving or soft ground improvement construction methods are being attempted (Japanese Patent Application Laid-open Nos. 50-161016 and 52-80605).

No. 50-86809, No. 48-49233, Special Publication No. 53-37107, No. 58-33328, No. 49-
No. 49056). However, the current situation is that none of these methods has become a definitive improvement method.

The insulation method that has been attracting attention recently has a compressive strength of 0.9 to 3.
- This is a construction method in which a 0 kg/cJ foamed polystyrene block or plate material is used as the laying material, the existing road surface is dug out, this foam is placed, and new pavement is constructed on top of it, and it is attracting attention as a powerful construction method. It is widely practiced, especially in Northern Europe.

[Problem that the invention seeks to solve]

However, this construction method is not a definitive solution to the main problem of frost heaving prevention.

In other words, the expanded polystyrene produced using this method has high shear strength,
Because compressive strength, tensile strength, frictional strength, restoring performance, etc. are not sufficient, material failure occurs due to heavy objects such as automobiles, and roads become caved in or wavy. In addition, since it does not have a drainage function, underground water tends to accumulate in the ground (roadbed), and it is easy to freeze up in winter, so it is not a fundamental solution to soft ground.

The present invention aims to solve such conventional problems,
A water insulating plastic foam having high compressive strength and high shear force is provided as the heat insulating foam to be laid, and a drainage mechanism is provided without impairing the function of the foam, and a water permeable layer is provided below the drainable heat insulating foam. This involves submitting methods for preventing frost heaving or improving soft ground.

In the method of the present invention, a plastic foam with high compressive strength and high shear force that can withstand heavy loads is used to insulate soil layers that are prone to frost heaving, reduce the need for roadbed materials, prevent temperature drop and prevent frost heave, and The drainage mechanism and permeable layer provided in this insulating foam actively drain groundwater, etc. that cause soft ground, thereby reducing moisture in the roadbed and improving the strength of roads and soft ground.

[Failure to solve the problem]

That is, the present invention applies 3.5 kg/an on the ground 10.
Drainage holes 6a in which a plurality of particles 6 for permeation of water are embedded are formed in an insulating plastic foam S having a thickness of 20 kg or more and having a compressive strength of t or more and a shear strength of 15 kg/CIA or more per area of 0.1 to 0.1 per area. Frost heaving prevention or frost heaving prevention characterized by providing a heat insulating foam 7 provided so as to penetrate vertically by 10χ, providing a water permeable layer 8 having a drainage function on the lower surface of the drainage hole 6a, and paving 3 on the heat insulating foam 7. This is a soft ground improvement method.

[For production]

Groundwater is drained through the drainage hole 6a of the heat insulating foam 7 and the gap between the water permeable holes N8, and water in the subgrade is further drained through the water permeable layer 8. Further, the ground 10 is insulated from the ground by the heat insulating foam 7.

〔Example〕

Hereinafter, the present invention will be explained in detail based on the drawings.

In FIG. 1, 1 is a roadway, and 2 is a sidewalk. 3 is a surface layer such as concrete or asphalt, and 4 is a roadbed. A water permeable heat insulating foam 7 is provided below this roadbed 4. This water permeable heat insulating foam 7 has a plurality of water permeable particles 6 embedded in a heat insulating plastic foam 5 with a thickness of 20 m or more and having a compressive strength of 3.5 kg/cn1 or more and a shear strength of 15 kg/cj or more. Drain holes 6a, 6a...
. . are provided so as to penetrate above and below by 0.1 to 10x per area.

This plastic foam 5 is 3.5 kg/c (2I
llI standard method JIS -6767) or more compressive strength and 15
kg/cIA (measurement method JIS K-7214) or higher, and preferably extrusion cross-linked foam molded polyolefin foam 5a (USP
4552708, Patent Application No. 57-225295, No. 58
-119643) with an apparent density of 40 to 320 kg/n?
(Measurement method JIS K-6767) is preferred.

More preferably, cross-linked high-density polyethylene foam 5
b (For example, Yukafoam!1O- manufactured by Mitsubishi Yuka Co., Ltd.
1000 (trade name)] is preferred. This Yuka Form H
The physical properties of D-1000 are as follows.

Polystyrene foam, which has an ungrooved compressive strength of 3.5 kg/cffl, is flexible and easily conforms to the ground 10, causing the surface to wave (becoming 15 kg/cffl).
Foams with a shear strength of /a+ (or less) tend to be cut by ground displacement (vertical movement), and the cut areas lose their insulation properties and are susceptible to frost heaving.

The apparent density of the polyolefin foam 5a is 40 to 320.
kg/n? The reason for this range is that if it is less than 40 kg/m, the compressive strength and shear strength will be weak.
This is because if it exceeds kg/I, the insulation performance will be poor. A more preferable apparent density is 45 to 195 kg/r/. The reason why the thickness of the polyolefin foam 5a is set to 20 mm or more is because if it is less than this, the heat insulation properties and shear resistance strength will be poor, and the load on the water permeable layer 8 will increase. The thickness of the insulation foam 7 varies depending on the freezing index of the region and the required shear strength, but it is approximately 50 m in the Tohoku region.
It is the rank.

The plastic foam 5 having the above performance has the effect of preventing the temperature of the ground 10 below from decreasing and maintaining it at a temperature that is difficult to freeze.

This heat insulating foam 7 has a drainage hole 6a in which a plurality of particles 6 for water permeation are embedded (see FIG. 2). This drainage hole 6a
is shown in the enlarged view of FIG. That is, the granules 6b are bonded or fused to each other so that a gap for water passage of 5 to 65χ is formed on the surface, and the structure is such that water can easily permeate through the gap 6c. Furthermore, it is desirable that the granules 6b have cutting performance, and are preferably made of hardened plastic, wood chips, or the like. More preferably, asphalt and a polymer adhesive are sprinkled on spherical foam particles made of thermoplastic resin such as foamed polystyrene, foamed polypropylene, and foamed polyethylene, and mixed to form a solid water-permeable cavity. A foamed heat insulating material with pores of 25 to 602 is preferred (the granules are manufactured by Mitsubishi Yuka Verdissier Co., Ltd. and Kitanihon Kagaku Kogyo Co., Ltd. under the trade name Styrodren).

The granules 6b have both heat insulating properties and waterproof properties, and exhibit an excellent drainage effect without clogging. The physical properties of this styrodrain are as follows.

Instead of the granules 6b, a foam chip 6d made of polystyrene, polypropylene, etc. as shown in FIG. 6(a) or a chip 6e of irregular shape as shown in FIG. 6(b) may be used. These chips 6d and 6e are welded to each other by melting their surfaces with pressurized steam in a mold.

Since the drainage hole 6a is made of the above-mentioned water-permeable structure and material, the groundwater that causes frost heave is removed from the water-permeable layer (water-permeable object) 8 that has a drainage function, such as the above-mentioned styrodrain, gravel layer, etc. In addition to being able to drain water to the fiber layer of the palm, it also has a heat insulating function, so it prevents a drop in temperature below the drainage hole 6a and functions to prevent frost heaving. If the drainage hole 6a is less than 0.1 to b per area, the drainage function will be poor, and if it is more than 10%, the mechanical strength of the heat insulating foam 7 will be adversely affected.

Furthermore, the density of this drainage hole 6a is preferably 0.3 to 5.0.
%. The density of drainage holes 6a also varies depending on the region,
There are about 3 holes of 50 dragon diameter per 4000uX340+n. A water-permeable object 8 having a drainage function (for example, the above-mentioned Styrodrain (trade name)) is provided below the drainage hole 6a. This water-permeable object 8 is shown in a plan view of the third view.
It is provided as shown in the sectional view shown in FIG.
guided by. Furthermore, this water passes through the drain pipe etc. 9a and is drained to the sewer 9.
Water on the 10 surfaces of the subgrade is discharged by flowing into b, etc.
Reduce moisture content in the subgrade.

The water permeable object 8 having a drainage function has a heat insulating function.

It has pressure resistance and drainage function. The planar shape is not particularly limited, such as a lattice shape or a branch shape, but the material is preferably the same as the granules 6b of the drain hole 6a, and more preferably a styro drain having heat insulating properties. Styrodrain has a pore volume of approximately 30 for continuous water flow.
2, it allows smooth drainage without clogging over a long period of time, and even if water adheres to the Styrofoam and freezes, the excellent physical properties of the Styrofoam as a buffer material will absorb the frost heaving pressure. The dimensions of object 8 also vary depending on the region, but it is approximately 150m wide x 300m deep.
It is f1st place.

〔Effect of the invention〕

The ground produced by the construction method of the present invention lowers the water content of the roadbed and roadbed surface by lowering the groundwater level, stabilizes the roadbed and roadbed, and replenishes shearing force, making it possible to reduce the need for roadbed materials. The weight of the roadbed is reduced, and subsidence of the roadbed, which is a noticeable phenomenon in soft ground, can be reduced. Furthermore,
The foam has insulating properties, which helps prevent frost heaving.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view of one embodiment of the ground constructed by the construction method of the present invention, Fig. 2 is a plan view showing the arrangement of drainage holes 6a, Fig. 3 is a plan view of the water permeable 11i8, and Fig. 4 is its A-A Line sectional view, Figure 5 is an enlarged cross-sectional view taken along line B-B in Figure 2, Figure 6 (A) (O)
FIG. 2 is a perspective view showing two examples of chips used in the present invention. 10...Ground, 5...Insulating plastic foam, 6...Grain, 6a...Drainage hole, 7...Insulation Foam, 8... Water permeable layer (object with drainage function), 3... Pavement (Table N). $5 So-called poor efu (a) (b) ~
b'6

Claims (2)

[Claims] (1) On top of the ground, multiple particles for water permeability are placed on an insulating plastic foam with a thickness of 20 mm or more and having a compressive strength of 3.5 kg/cm^2 or more and a shear strength of 15 kg/cm^2 or more. 0.1 to 10 embedded drainage holes per area
A frost heaving prevention or soft ground improvement method characterized by providing a heat insulating foam that penetrates vertically, providing a water permeable layer with a drainage function on the lower surface of the drainage hole, and paving on top of the heat insulating foam. (2) The frost heaving prevention or soft ground improvement method according to claim 1, wherein the insulating plastic foam is a high-density polyethylene foam.