JPH01312122A - Method for relieving earth pressure - Google Patents

Abstract

PURPOSE:To make relief of earth pressure with easy work and less expenses by placing a cover made of porous resin or blocks made of such porous resin over an underground structure body, and by inducing arching thereby. CONSTITUTION:A cover 2 formed of porous resin or blocks made of such porous resin is placed over an underground structure body 1. Compressibility of the earth is increased as a whole by the underground structure body 1 and the cover 2, making peripheral ground 5 sustain ore load of filling 3, and thereby earth pressure being applied to the underground structure body 1 can be relieved.

Description

[Detailed description of the invention] (Technical field) This invention relates to an earth pressure reduction construction method.

More specifically, this invention relates to a simple and economical earth pressure reduction method that can reduce the earth pressure of underground structures such as headrace tunnels and significantly improve pressure resistance. It is something.

(Background technology) Conventionally, in embankment construction methods for underground structures such as culvert hooks, the back of bridge abutments, or soft ground,
Various methods have been investigated to reduce the surrounding earth pressure.

For example, in recent years, as one such method, it has been proposed to use styrofoam instead of embankments on soft ground to reduce weight, stabilize it, and prevent subsidence. As an example of this, as shown in FIG. 3, it is known that Styrofoam (2) is placed when embanking (B) on soft ground (A).

However, the main purpose of using resins such as styrofoam is to reduce weight, such as when embanking on soft ground, and the way they are used is to simply stack blocks as shown in Figure 3. However, the use of lightweight materials such as styrofoam has not been realized to date.

(Purpose of the Invention) This invention was made in view of the above circumstances, and it is an object of the present invention to make even more advanced use of resins such as styrofoam, which is attracting attention as a new construction material that is lightweight and easy to handle.
The purpose of this study is to provide an earth pressure reduction method based on a new idea for use in earth pressure reduction methods for underground structures.

(Disclosure of the Invention) In order to achieve the above object, the present invention provides an underground structure that is characterized by forming a cover with a porous resin or a block thereof on the upper part of an underground structure to cause an arch action in the ground. The method for providing pressure relief is to reduce the earth pressure by causing an arch action in the ground, and to form a cover made of porous resin plates or blocks on top of the underground remains. However, the basic idea, specific structure, and effects are different from conventional embankment construction methods for soft ground.

FIG. 1 shows the principle of the construction method of this invention. FIGS. 1A and 1B show a comparison between a case in which an arch action is caused by forming a cover made of porous resin and a case in which it is not.

As shown in Figure 1(a), even if there is a hard structure (1) such as a box or tunnel underground, if a cover (2) made of porous lightweight resin is formed on top of it, In order to increase the compressibility of the underground structure (1) and cover (2) as a whole (because the whole is in the state of a very soft spring (4)), the surrounding ground (5) or the embankment (which has low compressibility)
By supporting more of the load of 3), the earth pressure acting on the underground structure (1) is reduced. On the other hand, when the cover (2) is not formed, the earth pressure is concentrated at the center of the hard underground structure (1) (a very hard spring state). This slump, especially in the case of existing underground structures, becomes extremely dangerous due to the concentration of this upper pressure.

In the construction method of the present invention, it is possible to support a larger foundation by the surrounding ground, so an extremely excellent earth pressure reduction effect can be achieved for the underground structure. This upper pressure reduction effect becomes important when burying or constructing structures underground, as well as repairing and protecting existing structures, and realizes greater pressure resistance and economic effects.

In the construction method of this invention, as the porous lightweight resin, foamed polystyrene, foamed polyethylene, and other materials with good water resistance and weather resistance and excellent properties such as compressive strength and compressibility may be used as appropriate. I can do it. These are used in the form of plates or blocks to form a cover on top of underground structures.

In this case, a protection work made of concrete or the like may be provided on the upper part of the underground structure, and a wall portion made of a porous resin plate or a block thereof may be formed thereon.

FIG. 2 shows an example of this invention.

This example shows a water pipe (6) in use as an underground structure.
This figure shows an example of reinforcement work for water conveyance g (6) when it is buried.

Since this water conduit (6) is currently in use, the inside cannot be directly reinforced. Furthermore, since internal pressure is acting on the water pipe (6) and the outer 3 m cannot be excavated, the outer side cannot be directly reinforced either. Furthermore, the height of the embankment (9) is approximately 5
Since the distance is 0 m, the average internal pressure is about 100 t. At this time, considering the regularity of the water pipe (6), a concentration of earth pressure occurs on the water pipe (6), and an earth pressure of about 150 t/d acts on the water pipe (6). This slant reinforcement needs to be performed more rationally and while suppressing an increase in load on the water pipe (6).

In this example, a protective arch concrete (7) with a thickness (11) of approximately 25 mm is placed, and on top of the
t2) or a cover made of about 40 [with] foamed cotton roll (
8). The inner diameter (R) of the protective arch concrete (7) is approximately 800 an. Embankment (9) is placed above and around the cover (8).

If this Styrofoam cover (8) is not provided, the inner diameter (R) of the protective arch concrete (7) is approximately 85 mm.
At 0aT+, the thickness needs to be about 600 cm.

As described above, the action and effect of the arch action of the ground according to the present invention are extremely large, and as shown in Table 1 below, in the embodiment of the present invention, the arch action of the ground is extremely effective. The compressive stress, the stress generated in the protective arch concretes 1 to (7), and the vertical earth pressure are much smaller than in the comparative example in which the resin cover (8) is not formed.

Construction costs can also be reduced by about 50% or more.

Table 1 (Effects of the invention) This invention makes it possible to significantly reduce the earth pressure on underground structures, and realizes an easy and low-cost construction method.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the principle of the construction method of the present invention. FIG. 2 is a sectional view showing an embodiment of the invention. FIG. 3 is a sectional view showing the conventional embankment construction method. 1... Underground structure 2... Porous resin covering 3.
... Embankment soil 4 ... Soft spring 5 ... Surrounding ground 6 ... Water pipe 7 ... Protective arch concrete 8 ... Resin covering 9 ... Embankment agent Patent attorney Toshio Nishizawa

Claims (3)

[Claims] (1) An earth pressure reduction method characterized by forming a cover on the top of an underground structure with a porous resin plate or a block thereof to cause arch action of the ground. (2) Claim (1) in which the underground structure is a tunnel structure.
Earth pressure reduction method described. (3) The earth pressure reduction method according to claim (1), wherein the wall portion is arranged on the upper surface of the protection work.