JPS61130514A - Cut-off work for fill-dam - Google Patents

Abstract

PURPOSE:To reduce the cost of construction work by a method in which imperfect cut-off zones for forming a core are constructed for each section over the heightwise direction, and a water-impervious geotextile cut-off film is made to cover the slope and top of each section. CONSTITUTION:The first stage section 1A for imperfect cut-off zone is constructed, and sections 2A and 3A for the first stage semi-water permeable zone 2 and water permeable zone 3 are constructed on the downstream side. A geotextile cut-off film 4 is covered on the slope and top of the section 1A, and sections 2A and 3A for the first stage semi-water permeable zone and water permeable zone are constructed on the upstream side of the section 1A. The second stage section 1B is constructed on the section 1A, and sections 2A and 3B for the second stage semi-water permeable zone and water permeable zone are constructed on the downstream side. The film 4 is covered on the slope and top of the section 1B, and its lower end is partly lapped with the film 4 of the section 1A. The second stage semi-water permeable zone and water permeable zone section is constructed on the sections 2A and 3A on the upstream side of the section 1B. The same processes are repeated in order.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a water-blocking method for zone-type fill dams.

(Prior art) As shown in Figure 6, a conventional zone-type fill dam has a water-blocking zone (α) in the center of the dam body, and a semi-permeable zone (A) and a permeable zone (C) on the outside of the water-blocking zone (α). ) is layered with a central core type and an inclined impermeable zone (α
) is a sloped core type zone pear dam.

The difference between central core type and inclined core type zonal dams depends on the circumstances of each dam site, but the soil material used for the impermeable zone generally has a permeability coefficient of 1O-6 during compaction. (7)/S It is desirable that it be smaller.

However, recent fill dams tend to have higher heights, and it is now necessary to secure a larger amount of impermeable zone material than ever before. It has become difficult to find it in its natural state.

Therefore, in many dam sites, in order to secure impermeable zone materials, for example, when compacting natural soil materials, material A, which has a hydraulic conductivity of 10-4 cm/S, and material A, which has a hydraulic conductivity of 10-4 cm/S, are used. Material B which is 10-7cm/S
Waterproof zone materials are often created by appropriately blending the water and water.

However, in order to blend material A and material B in this way, although there are examples of blending directly at the impervious seam on the fill dam body, it is necessary to secure a site for blending the impermeable materials and do this. Material A and material B are often laid out in alternating layers in a sandwich-like manner within the site and stirred during loading as the need arises to transport the materials to the impermeable zone.

(Problem that the invention attempts to solve) In the conventional method, both materials A are used as described above.

There were problems in terms of cost, such as the fact that blending site B was generally required, and rolling, compaction, and loading were required for blending.

Furthermore, if the impermeable material B to be blended was not present at the dam site, difficulties in dam design could not be avoided.

(Means for Solving the Problems) The present invention has been proposed in order to solve the above problems, and the present invention has been proposed in order to solve the above problems. A geotextile impermeable membrane is applied to the upstream slope of the section and the top surface connected to the slope, and then an upper incomplete impermeable zone component section is constructed to a predetermined height on the section. , cover the upstream slope of the same section and the top surface connected to the slope with a water-blocking film on the geotextile, and at the same time cover the lower end of the geotextile water-blocking film with the geotextile water-blocking film of the lower section. The present invention relates to a fill dam water shielding method characterized in that the above-mentioned steps are repeated.

(Function) As described above, in the present invention, an incomplete impermeable zone forming the core of a zone-type fill dam is constructed in each section along the height direction of the embankment, and the upstream slope and The top surface connected to the slope is covered with water-impermeable geotextile (1tttxtilt) made of chemical products.
) At the same time as covering the water-shielding membrane, the lower end of each geotextile water-shielding membrane was partially overlapped with the geotextile water-shielding membrane covering the slope of the lower section, so that the material of the incomplete water-shielding zone Even if the permeability coefficient is tentatively 10-3α/S, a water-blocking zone can be constructed by combining this material with geotextile.

As the geotextile water-blocking membrane, for example, No-Imerid Sheet (trade name) manufactured and sold by Mitsui Toatsu Chemical Co., Ltd. is used, and this is a composite sheet in which a soft vinyl chloride sheet is layered on a non-woven fabric. .

(Effects of the Invention) According to the present invention, by combining the material of the incomplete impermeable zone forming the core of the zone-type fill dam with the geotextile, the same material has a hydraulic conductivity of I
Even Q-3an/S can constitute a core having water-blocking properties.

Furthermore, according to the present invention, the geotextile that makes up the water-shielding membrane does not deteriorate due to water quality, there is no risk that the water-shielding membrane will break during zone construction, and it can withstand stress generated in the membrane due to earthquakes. Furthermore, even if the incomplete water-blocking zone sinks, the water-blocking membrane made of geotextile will follow this, making it possible to cope with the uneven settlement that is inevitable when constructing high-quality materials.

As described above, according to the present invention, even in dam sites where only materials that cannot be used as material for the water-blocking zone of fill dams are available, a water-blocking membrane can be constructed by using geotextile, and it is possible to construct a water-blocking membrane by using geotextiles. There is no need to blend poorly permeable materials in the ground, and zone-type fill dams can be constructed economically.

(Example) The illustrated example in which the method of the present invention is applied to the construction of a zone-type dam will be described below.

The first stage component section (LA) of the incompletely impermeable zone (1) is constructed to the required height, and the first stage semi-permeable zone (2) is constructed on the downstream side.
) and each section (2A) (2B) of permeable zone (3). (See Figure 2A) At this time, construction on the upstream side will be slightly delayed due to the construction of the impermeable membrane, so it is necessary to appropriately determine the construction thickness h of the incomplete impermeable zone section shown in Figure 3. be.

This h depends on the rainfall erosion resistance of the incompletely impermeable zone, but
Usually there are 3 to 5 wings.

Next, a geotextile waterproof membrane (4) is coated over the slope of the first stage component section (one person) and the top surface connected to the same surface, and the upstream of the section (LA) is coated (see Figure 2B). Construct the first stage semi-permeable zone and permeable zone components (2A) and (3A) on the side. Next, the second stage component section (IB
), and on the downstream side, construct the second-stage structural sections (2B) and (3B) of the semi-permeable zone and the permeable zone.

(See Figure 2C) Next, the slope of the constituent section (2B) of the second-stage incomplete water-shielding zone and the top surface connected to the same surface are covered with the geotextile water-shielding film (4), and the same water-shielding film (4) is applied. A water-blocking membrane (4) covering the lower end of the water membrane (4) with the first stage section (LA)
(See Figure 2D).

It goes without saying that the side edges of the water-shielding membranes (4) that are adjacent to each other in the longitudinal direction of the embankment body may also partially overlap. (See Figure 4) Next, the first stage semi-permeable zone, permeable zone and permeable zone on the upstream side of the division (IB) (=>
(3A) A second semi-permeable zone and a permeable zone are constructed on top, and the same steps as described above are repeated to construct a zone-type fill dam.

The overlapping margin m of the vertically adjacent water-shielding membranes (4) is determined by the dimension t1 of the horizontal portion of the water-shielding membrane (4) at the top surface of the section of the incomplete water-shielding zone and the width of the incomplete water-shielding zone. Determined by the hydraulic conductivity and ease of construction of the embankment.

Further, the dimension 2 is determined by the workability of the impermeable membrane and the permeability coefficient of the incomplete impermeable membrane in the upper layer.

For example, the permeability coefficient of the incomplete impermeable zone material is 1O-4an.
/ If it is S, l :2.577! , nt
= l vn.

The water barrier #(4) polymerizes only by nailing its horizontal portion to the component section of the incomplete water barrier zone, and generally does not adhere.

By not adhering the water-shielding membrane (4) in this way, some water leaks from the polymerized portion of the water-shielding membrane (4), but this may cause an excessive water pressure difference in the water-shielding membrane (4). prevent,
Provides flexibility in the selection of water-blocking membrane (4). Appropriate water leakage is also suitable for ecological preservation downstream of the fill dam.

The impermeable membrane suspended from the top, together with the lower impermeable membrane, comes into close contact with the earth pressure when constructing the semi-permeable zone, and becomes even more intimate with the water pressure during flooding.

FIG. 5 shows an embodiment in which the present invention is applied to the construction of Hoon-huang Dam, in which at+ is a uniform zone, (12) is a drainage zone, and α3 is a water-blocking membrane.

Although the present invention has been described above with reference to embodiments, the present invention is, of course, not limited to such embodiments, and can be modified in various ways without departing from the spirit of the present invention. .

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a zone-type fill dam constructed by the method of the present invention, FIGS. 2A to 2D are construction process diagrams, and FIG. 3 is a partial vertical cross-sectional view of the incomplete impermeable zone.
Fig. 4 is a partially cutaway plan view showing the arrangement of the impermeable membrane, Fig. 5 is a longitudinal cross-sectional view of the Hokkaido dam constructed by the method of the present invention, and Figs. 6 and 7. is a vertical cross-sectional view of a conventional zone type fill dam. (1)...Incomplete impervious zone, (2)...Cow permeable zone, (3)...Water permeable saw 7, (4)...Waterproof membrane,
αυ...uniform zone, (l■...drainage zone, Q3
...Waterproof membrane agent Patent attorney Shige Okamoto 3 other people

Claims (1)

[Claims] An incomplete impermeable zone constituent section that forms the core of a zone-type fill dam is constructed to a predetermined height, and a geotextile impermeable membrane is covered over the upstream slope of the section and the top surface connected to the slope. An upper incomplete impermeable zone component section is constructed to a predetermined height on the above section, and the upstream slope of the section and the top surface connected to the slope are covered with a geotextile impermeable membrane. A fill dam impermeable construction method characterized in that the lower end of the impermeable membrane is superimposed on the geotextile impermeable membrane of the lower category, and the same steps as described above are repeated thereafter.