Hydraulic and earth engineering – Underground passageway – e.g. – tunnel – Lining
Reexamination Certificate
2002-12-05
2004-09-21
Lee, Jong-Suk (James) (Department: 3673)
Hydraulic and earth engineering
Underground passageway, e.g., tunnel
Lining
C405S150100, C405S146000
Reexamination Certificate
active
06793441
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
1. Technological Field of the Invention
This invention relates to a waterproofing method for tunnels.
In this invention, paste, mortar and concrete are used as general terms to refer to cement concrete.
2. Prior Art
The principal tunnel construction method in Japan at present is the NATM method. The NATM construction method is a method in which primary coating is performed by means of spray mortar or spray concrete immediately after excavation of the tunnel to prevent falling of rock and water leakage in the excavation region, after which a secondary coating concrete is applied to stabilize the tunnel by maintaining tunnel strength. At this time, a waterproofing sheet is installed for the purpose of waterproofing and insulation between the primary coating concrete and the secondary coating concrete so that leakage of water into the tunnel can be prevented and so that cracks due to binding of the secondary coating concrete to earth mounds or movement of earth mounds can be prevented. Most recently, tunnel excavation has been performed by tunnel boring machines (TBM construction method) and waterproofing sheets are installed for the same objectives.
Further, because the width of the sheet is narrow, being 1 to 2 m, there are the problems that it takes great effort and trouble and it is uneconomical when the ends of the waterproofing sheets are overlaid on each other and joined by welding.
There is the further problem that water infiltrates between the waterproofing sheets and the secondary coating concrete due to damage of the waterproofing sheet functionally by poorly welded components and by irregularities in the excavation surface so that waterproofing capacity is not obtained.
[Problems the Invention is Intended to Solve]
When the thickness of the waterproofing sheets is increased in order to prevent damage to the waterproofing sheets, there are the problems that welding of the ends of the waterproofing sheets becomes difficult and that the mass of the waterproofing sheets is increased, with the result that actual execution characteristics become even poorer.
The inventors conducted various studies of the aforementioned problems. As a result, they perfected this invention by discovering a tunnel waterproofing construction method whereby a waterproofing sheet that is adhesive to the secondary coating cement concrete is installed on the primary spray cement concrete surface before installing the secondary coating cement concrete, and, in which, by making it into a single entity with the secondary coating cement concrete, infiltration of water between the waterproofing sheet and the secondary coating concrete because of poor weld sites and damage of the ends of the waterproofing sheets is prevented, leakage of water is prevented even when cracks are generated in the secondary coating cement concrete and waterproofing capacity can be greatly increased.
[Means for Solving the Problems]
Specifically, this invention is a tunnel waterproofing method characterized in that a primary spray cement concrete is sprayed on the excavation surface of the tunnel, after which a secondary coating cement concrete and a waterproofing sheet having adhesiveness are installed on said primary spray cement concrete surface such that the secondary coating cement concrete is established on said waterproofing sheet surface, [or] a tunnel waterproofing method characterized in that a primary spray cement concrete is sprayed on the excavation surface of the tunnel, after which a buffer-water conducting layer is established in said primary spray cement concrete surface, a secondary coating cement concrete and a waterproofing sheet having adhesiveness are installed on said secondary coating cement concrete such that the secondary coating cement concrete is established on said waterproofing sheet surface; and a tunnel waterproofing method further characterized in that the waterproofing sheet is a multilayer waterproofing sheet that has a layer that has adhesiveness with the installed secondary coating cement concrete.
[Mode of Execution of the Invention]
We shall now describe this invention in detail.
This invention is a construction method in which the waterproofing sheet and the tunnel are made into a single entity by spraying, preferably, a fast-drying cement concrete onto the excavated tunnel surface, after which a waterproofing sheet that is adhesive with the secondary coating cement concrete is installed. This waterproofing sheet allows for follow-up of cracking of cement concrete due to drying and contraction of the secondary coating cement concrete and of earth mounds after completion. By making the cement concrete and the waterproofing sheet into a single entity, contact with water occurs only in sites that are damaged even if damage to the waterproofing sheets occurs. For this reason, leakage of water does not occur as long as cracks do not develop in the secondary coating concrete in the region of the sheet damage. Therefore, water leakage is greatly decreased and excellent waterproofing capacity is obtained. Further, water leakage does not occur as with conventional waterproofing sheets as a result of water infiltrating between the waterproofing sheet and the secondary coating cement concrete, of impairment of the waterproofing capacity of the tunnel as a whole, and of cracks in the secondary coating cement concrete. Moreover, because a waterproofing sheet that is made into a single entity with the secondary coating cement concrete prevents water leakage with good follow-up capacity and without damage occurring even when cracks are generated in the tunnel itself, waterproofing capacity is increased to a great extent by comparison to conventional waterproofing construction methods.
Examples of waterproofing sheets that are adhesive with secondary coating cement concrete include uncrosslinked rubber sheets such as isoprene rubber and natural rubber.
The waterproofing sheet that is adhesive with the secondary coating cement concrete may also contain antioxidants, ultraviolet radiation absorbents and tackiness-decreasing agents.
In this invention, it is desirable to laminate the layer having adhesiveness with the secondary cement concrete with a polymeric sheet from the standpoint of increasing the insulation effect with the secondary coating cement concrete if it has been bound with the earth mound. When a layer that is adhesive with the secondary coating cement concrete and a multilayer waterproofing sheet that is laminated with a polymeric sheet are used, they are installed so that the primary spray cement concrete surface side and the polymeric sheet are in contact and the secondary coating cement concrete is installed on the waterproofing sheet surface side that is adhesive with the secondary coating cement concrete.
Examples of the material of the polymeric sheet can include high-density polyethylene, low-density polyethylene, copolymers of ethylene vinyl acetate (EVA) and polypropylene. Of these, high-density polypropylene is preferable from the standpoint of insulation effect, strength, crack follow-up capacity and price.
In this invention, a buffer-water conducting layer may be established before installing the waterproofing sheet that is adhesive with the secondary coating cement concrete for the purpose of increasing the insulation effect, decreasing water pressure in sites in which there is a great deal of groundwater and increasing the waterproofing effect. Examples of buffer-waterproofing layers can include layers that are formed by spraying a fibrous substance such as pulp nonwoven fabrics of fibers such as polyester fibers and polypropylene and plates or irregular shapes.
The waterproofing construction method can be used in the bedding portion of the tunnel and displays great effectiveness in preventing water leakage from the bedding component.
There are no particular limitations on the method of affixing the waterproofing sheet, nonwoven fabric and plates of irregular shape to the primary spray cement concre
Kosuge Keiichi
Shimizu Sachio
Baker William L.
Lee Jong-Suk (James)
Leon Craig K.
W. R. Grace & Co.,-Conn.
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