Seepage-proofing structure of concrete faced rockfill dam
Technical Field
The invention relates to the technical field of water conservancy and hydropower engineering, in particular to an anti-seepage structure of a concrete faced rockfill dam.
Background
The prior art face sheet rock-fill dam barrier construction form generally includes from upstream to downstream a toe plate, and on the downstream side of the toe plate a barrier layer, rock-fill material, face sheet. In recent years, geomembrane has been widely used gradually due to good seepage-proofing performance and strong adaptability to deformation, so that a geomembrane face plate rock-fill dam is formed. Namely, the flexible geomembrane is adopted to replace a panel to be used as an impermeable layer, and a certain effect is achieved. The impermeable structures of geomembrane replacement panels typically comprise an upper protective layer, a geomembrane, a lower support layer (typically extruded sidewalls are used as support layers), and a rock fill material.
Whether the concrete faced rockfill dam (such as a face rockfill dam seepage-proofing structure disclosed by patent CN 105672205B) or the geomembrane faced rockfill dam (such as a mixed dam type structure of a homogeneous rockfill dam and a face rockfill dam disclosed by patent CN 206529745U; and a concrete faced rockfill dam seepage-proofing structure disclosed by CN 110042800A) has certain defects, which are as follows:
1) for the concrete face rockfill dam, because the cushion material and the face plate are discontinuously deformed, the face plate and the cushion material are easy to contact and separate, namely, the general phenomenon of void occurs, the face plate deforms under the action of upstream water load, a downstream pot bottom shape is formed in space, the face plate loses a supporting layer at the void part, local damage is easy to occur, even the face plate is broken, once the face plate is broken, serious influence is brought to seepage prevention, even the safety of the dam is endangered, and the situation that the face plate is broken in the concrete rockfill dam at home and abroad occasionally occurs.
2) For the concrete face rockfill dam, under the action of dead weight, a dam body (bedding material, transition material and rockfill material) deforms from two banks to a river valley, and simultaneously drives the panels at the two banks to deform towards the middle of the river valley, so that the panels in the middle of the river valley generate large extrusion stress, local extrusion damage is easily generated at the seams between the panels, the seepage prevention function of the panels is influenced, and the phenomenon often occurs in the face dam.
3) For the earth work membrane face plate rock-fill dam, the earth work membrane is adopted to directly replace a face plate to be used as a dam impervious layer, because the lower supporting layer (usually, an extrusion side wall is adopted as the supporting layer) has relatively low strength and modulus, and no structural seam is arranged in the cross river direction, the extrusion damage and structural crack are easily generated under the action of the dead weight of the dam body and water load, so that the impervious layer of the earth work membrane is punctured or torn to form leakage; because the lower supporting layer is not provided with a structural seam, the geomembrane is not divided into zones, so that one point of leakage can be caused to leak from the whole dam surface, and the development speed is high.
4) For the earth work film face plate rock-fill dam, when the water level suddenly drops, the water in the reservoir rapidly drops, and the water in the rock-fill material slowly drops, so that the water level in the dam body is high, the reservoir water level is low, the earth work film is easy to separate from the downstream cushion area under the action of the water level difference, and the jacking phenomenon occurs.
5) For the earth work membrane face plate rock-fill dam, the earth work membrane is directly arranged on the surface, and under the action of wind, sunshine, rain and water immersion, the phenomena of aging, penetration of floating objects, freezing, pulling crack and the like easily occur.
6) In case of leakage, the operation and maintenance are inconvenient, the safety of the dam can be seriously endangered and the operation cost is increased.
Disclosure of Invention
The invention aims to provide the seepage-proofing structure of the face rockfill dam with good stress performance, good water-stopping effect and high safety performance.
The technical scheme of the invention is as follows: the seepage-proofing structure of the concrete faced rockfill dam comprises bedrock and toe boards positioned on the bedrock, wherein a seepage-proofing layer which is flush with the toe boards is arranged on the downstream sides of the toe boards, rockfill materials, a transition layer, bedding materials, a geomembrane and a face board are sequentially arranged from the seepage-proofing layer to the upper part, and the side surfaces of the toe boards facing the downstream sides are construction surfaces;
the panel, the geomembrane, the bedding material, the transition material, the rockfill material and the impermeable layer are all in contact with the construction surface.
In the scheme, the advantages of the concrete face rockfill dam and the geomembrane face rockfill dam are combined, the face plate, the geomembrane, the water stop copper sheet, the toe plate, the impervious layer, the impervious curtain and the bedrock form an integral impervious system, and the integral stress performance is improved;
the double-layer composite panel formed by the concrete panel and the geomembrane is adopted, the anti-seepage effect of the panel rock-fill dam is greatly improved, and the panel is arranged on the surface of the geomembrane, so that the aging speed of the geomembrane can be effectively delayed, the durability is improved, and the effects of preventing the geomembrane from being punctured by upstream floaters, freezing and tearing, reversely supporting water and the like are avoided.
Preferably, a water stop copper sheet is arranged at the contact part of the panel and the construction surface.
Preferably, a water stop copper sheet is arranged at the contact part of the impermeable layer and the construction surface.
Preferably, the geomembrane is bent toward the bedding material at the position of the construction surface and detachably connected with the toe board through a fastener.
Preferably, the waterproof curtain is arranged in the bedrock and close to the toe board.
Compared with the related technology, the invention has the beneficial effects that:
firstly, an integral seepage-proofing system is formed by the face plate, the geomembrane, the water-stopping copper sheet, the toe board, the seepage-proofing layer, the seepage-proofing curtain and the bedrock, so that the water-stopping effect of the dam is ensured;
the double-layer composite face plate of the concrete and the geomembrane is adopted, so that the seepage-proofing effect of the face plate rock-fill dam is greatly improved, the stress performance and the seepage-proofing effect of the traditional face plate rock-fill dam structure are greatly improved, and the safety of the dam is improved;
the construction of the geomembrane and the concrete panel is not interfered with each other, the geomembrane is combined with the arrangement of the panels to carry out partition design, and each panel is taken as an independent seepage-proofing partition to avoid the leakage of the damaged whole dam surface at one part of the geomembrane;
construction is convenient, the anti-seepage effect and safety are improved, the engineering operation and maintenance cost is reduced, and better engineering benefit is achieved;
and fifthly, the concrete panel is arranged on the surface of the geomembrane, so that the aging speed of the geomembrane can be effectively delayed, the durability is improved, and the effects of preventing the geomembrane from being punctured by upstream floaters, preventing the geomembrane from being broken by freezing, and preventing reverse water jacking and the like are achieved.
Drawings
Fig. 1 is a schematic cross-sectional view of an impermeable structure of a concrete faced rockfill dam provided by the invention.
In the attached drawing, 1-geomembrane, 2-panel, 3-bedding material, 4-transition material, 5-rockfill material, 6-waterproof copper sheet, 7-toe board, 71-construction surface, 8-impermeable layer, 9-impermeable curtain, 10-bedrock and 11-fastener.
Detailed Description
The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings. It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. For convenience of description, the words "upper", "lower", "left" and "right" in the following description are used only to indicate the correspondence between the upper, lower, left and right directions of the drawings themselves, and do not limit the structure.
As shown in fig. 1, the present embodiment provides a seepage-proofing structure of a face rockfill dam, which comprises a bedrock 10 and toe boards 7 positioned on the bedrock 10, wherein the downstream sides of the toe boards 7 are provided with seepage-proofing layers 8 which are flush with the toe boards 7. And a rockfill material 5, a transition layer 4, a bedding material 3, a geomembrane 1 and a panel 2 are sequentially arranged from the impermeable layer 8 to the upper part, and one side of the toe board 7 is a construction surface 71.
The panel 2, the geomembrane 1, the bedding material 3, the transition material 4, the rockfill material 5 and the impermeable layer 8 are all in contact with the construction surface 71.
The face plate 2 is concrete and the upper surface of the face plate 2 is flush with the upper surface of the toe plate 7. The geomembrane 1 is arranged below the face plate 2, and the height range of the geomembrane extends from the dam crest to the toe plate 7. The geomembrane 1 is bent towards the bedding material 3 at the position of the construction surface 71 and is detachably connected with the toe board 7 through a fastener 11. In the present embodiment, the fastening member 11 is a bolt. After the geomembrane 1 is fixed on the toe board 7, the bedding material 3 is constructed.
And water stop copper sheets 6 are arranged at the contact parts of the panel 2 and the construction surface 71 and the contact parts of the impermeable layer 8 and the construction surface 71. The water stop copper sheet 6 is a copper alloy for water drainage of hydraulic engineering, which is made of red copper with copper content of more than 99.9%, has good corrosion resistance and tensile property, has good water drainage and leakage prevention performance, and plays a role in protecting the hydraulic engineering so as to achieve the effect of water stop of seepage prevention.
An impervious curtain 9 is arranged in the bedrock 10 according to the depth of the relative impervious layer, and the impervious curtain 9 is arranged close to the toe board 7.
An integral seepage-proofing system is formed by the geomembrane 1, the panel 2, the water-stopping copper sheet 6, the toe board 7, the seepage-proofing layer 8, the seepage-proofing curtain 9 and the bedrock 10, so that the water-stopping effect of the dam is ensured.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.