JPH04131430A - Underground structure - Google Patents

Abstract

PURPOSE:To prevent the ground from floating up or sinking due to liquidification of the ground by providing a cut-off wall reaching a water- impermeable stratum from the ground surface arround the concrete body installed in the ground and closely sticking this cut-off wall to the wall face of the concrete body via an asphalt layer. CONSTITUTION:A reinforced concrete body 1 is arranged to use for a common ditch in the ground 2. Next, cut-off walls 3, 3 are provided at the area surrounding the concrete body 1 to reach the water permeable stratum 4 from the ground surface. Moreover, an asphalt layer is laid between the wall face of the concrete body 1 and the cut-off walls 3, 3 to closely contact each other. In this way, even when a liquidifying is brought about at the outer area of the cut-off walls 3, 3, these prevent the underground water from flowing into the surrounding area of the concrete body 1 and hence, the liquidifying does not easily happen in the inside of the cut-off walls 3, 3. And the asphalt layer 5 has a resistance against the deformation of the concrete body 1 due to an earthquake because of the visco-elasticity of the asphalt layer 5 to prevent the concrete body 1 from floating up and sinking down.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to an underground structure that can prevent damage such as uplift and subsidence due to liquefaction of the ground.

"Conventional technology and its problems" As is well known, disasters occur in which the ground liquefies during earthquakes, causing structures to rise or sink.As a countermeasure, sand compaction methods, vibroflotation methods, etc. are being used. Although soil compaction is widely practiced, these methods inevitably generate vibration and noise, making it difficult to implement, especially in urban areas. Also,
Other methods that can be implemented in urban areas include the gravel drain method and a method that hardens the ground with cement, but these methods increase construction costs and may not always be sufficiently effective.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an underground structure that can effectively prevent damages such as uplift and subsidence caused by liquefaction of the ground.

``Means for Solving the Problems'' The present invention is an underground structure that can prevent damage such as uplift and subsidence caused by liquefaction of the ground, and which is constructed so that the structure is installed underground and is The structure is characterized in that a water-stopping wall reaching the impermeable layer is provided, and the water-stopping wall and the wall surface of the frame are brought into close contact with each other with an asphalt layer interposed therebetween.

"Function" In the underground structure of the present invention, the water stop wall prevents groundwater around the frame from flowing in.

In addition, the rigidity of the water-stop wall makes it difficult for the ground under and around the structure to liquefy, and even if liquefaction occurs, the rise in water pressure at the bottom of the structure is kept to a level below the ground pressure of the structure. This prevents the floating phenomenon from occurring and prevents major damage. The asphalt layer interposed between the water cut-off wall and the building structure wall prevents water and sand from ejecting from the bottom, and has properties as a viscoelastic material, so it acts as an elastic material during an earthquake and strengthens the structure. It exerts resistance against sudden displacement and suppresses uplift and subsidence. In addition, in the long term, it acts as a viscous body and does not restrict the displacement of the structure due to the dissipation of water pressure after an earthquake, so the structure is always supported by the bottom after an earthquake.

"Embodiment" An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In these figures, reference numeral 1 indicates a reinforced concrete frame installed in the ground 2 that is likely to cause liquefaction and is used as a common ditch, and 3 indicates an impermeable layer (clay layer) 4 from the ground surface.
A highly rigid water stop wall made of reinforced concrete, for example, is installed to reach
This is an asphalt layer interposed between the

As mentioned above, in an underground structure having a water cutoff wall 3.3 that reaches the impermeable layer 4 on the outside of the frame 1, the ground 2
This can effectively prevent damage such as lifting or sinking of the frame 1 due to liquefaction.

That is, since the frame 1 is surrounded by the water-stop walls 3, 3, even if liquefaction occurs outside the water-stop walls 3, 3, groundwater is prevented from flowing around the frame 1. In addition, water stop wall 3
．． Increase in water pressure due to liquefaction inside 3.3 is suppressed to a low level by blocking the water from the outside with the water stop wall 3.3. Furthermore, if the frame 1 were to lift even slightly, the water pressure inside the water stop wall 3.3 would drop rapidly, so no further lifting would occur, thus preventing major damage. Ru.

In addition, since the water cutoff wall 3.3 has high rigidity, the ground 2.
The shear deformation applied to the water-stop walls 3.3 is reduced by the rigidity of the water-stop walls 3.3, which also has the advantage of making it difficult for the ground 2 to liquefy.In this respect, increasing the rigidity of the water-stop walls 3. It is desirable to leave it there.

Furthermore, the asphalt layer 5 naturally acts as a waterproof layer on the wall surface of the building frame 1, but since asphalt has properties as a viscoelastic material, the asphalt layer 5 acts as a viscous material in the long term. Therefore, at all times, the load on the skeleton 1 is transferred to the water stop walls 3,
3, the asphalt layer 5 acts as an elastic material during an earthquake and exerts resistance against sudden displacement of the frame 1.

In addition, the earth pressure applied to water supply 1!3.3 is asphalt layer 5.
, 5 to the building frame 1. Further, the water-stop walls 3, 3 may of course be provided with the main purpose of water-stopping, but if they can reach the impermeable layer 4, they can also be used as temporary stoppers.

As described above, the underground structure of the above embodiment can effectively prevent damage caused by liquefaction of the ground 2, and does not require improvement work such as compaction of the ground 2. , it does not generate noise or vibration like when implementing compaction methods such as sand compaction method or pipe rotation method.
It is also advantageous in terms of construction costs.

Note that similar effects can be obtained by substituting soft clay or the like instead of asphalt. Moreover, although the above embodiment is applied to a public ditch, it goes without saying that the invention can be applied in exactly the same way to other general underground structures and basement portions of buildings having underground floors.

"Effects of the Invention" As explained in detail above, the underground structure of the present invention has the following features:
The structure is constructed with a water-stop wall that reaches from the ground surface to the impermeable layer around the underground structure, so even if liquefaction occurs outside the water-stop wall, groundwater will still flow into the area around the structure. As a result, liquefaction inside the water stop wall is less likely to occur, and even if liquefaction occurs, the rise in water pressure will be kept low, and if the building structure lifts even slightly, the water stop wall will close. Since the water pressure inside the tank drops rapidly, no further uplift occurs, and major damage can therefore be prevented. In addition, since the water cut-off wall and the wall surface of the building structure are in close contact with each other through the asphalt layer, the asphalt layer exerts resistance against the displacement of the building structure during an earthquake due to the properties of the asphalt layer as a viscoelastic material. , there is also an advantage.

[Brief explanation of the drawing]

FIGS. 1 and 2 show an embodiment in which the present invention is applied to an underground structure used as a common ditch. FIG. 1 is a plan view of the location, and FIG. 2 is a plan view. 1...Structure, 2...Ground, 3...
...Water-stop wall, 4... Impermeable layer, 5...
asphalt layer.

Claims (1)

[Claims] This is an underground structure that can prevent damage such as uplift and subsidence caused by liquefaction of the ground, and is constructed by installing a water-stop wall that reaches from the ground surface to an impermeable layer around the framework installed underground. An underground structure characterized in that a water-stop wall and a wall surface of the framework are brought into close contact with each other with an asphalt layer interposed therebetween.