CN212477620U - Structure for building gravity dam on deep and thick covering layer - Google Patents

Abstract

The utility model discloses a structure for building a gravity dam on a deep covering layer, which comprises a gravity dam with a concrete structure, wherein a horizontal cover plate and a vertical downward diaphragm wall are arranged at the upstream of the gravity dam; a stilling pool, a stilling pool tail sill and a downstream apron are sequentially arranged at the downstream of the gravity dam; the lower part of the bottom plate of the stilling pool tail sill is provided with an impact wall which is vertically arranged downwards, the top of the impact wall is connected with the bottom plate of the stilling pool tail sill, and the bottom of the impact wall penetrates through the covering layer to the bedrock; vibroflotation piles are arranged above the covering layer, and a dense soil body is formed between the vibroflotation piles. Compared with the prior art, the utility model discloses effectively solve on the deep sand ovum gravel layer that the bearing capacity that gravity dam foundation exists is insufficient, warp too big, the permeability is strong, easily elutriate key problem such as destruction, is favorable to reducing abandon the slaggery and levy and water conservation measure, is favorable to saving engineering investment, protection ecological environment.

Description

Structure for building gravity dam on deep and thick covering layer

Technical Field

The utility model relates to a build structure of gravity dam on deep overburden belongs to hydraulic and hydroelectric engineering technical field.

Background

The gravity dam is a dam type widely applied to the hydraulic and hydroelectric engineering at home and abroad, and is generally built on a fresh and complete weakly-weathered to slightly-weathered rock foundation, and the higher the dam body is, the higher the requirement on the foundation is. Most dam foundation riverbeds are distributed with a quaternary sand-gravel washout layer, and for the condition that the thickness of a covering layer is not large, the covering layer is generally dug out, the surface weathered broken bedrock is removed, and then the gravity dam is built on the fresh and complete bedrock. However, in actual engineering, the situation that the dam foundation riverbed is distributed with deep covering layers is often encountered, if the covering layers are completely dug, the difficulty of supporting and draining the deep foundation pit is high, the construction period is long, the engineering investment is large, and a large amount of waste slag is very unfavorable for environmental protection; if the earth-rock dam is selected and used on a river channel with a narrow river valley, the problem that flood discharge buildings are difficult to arrange and the like may exist.

The engineering examples for building the gravity dam on the deep covering layer at home and abroad are less, and the design standard for building the gravity dam on the covering layer is not available according to the current regulations and specifications. The construction of gravity dams on a covering layer mainly has the following engineering difficulties:

firstly, for the rock-based, sand ovum gravel covering is generally comparatively loose, and it is less to allow uneven coefficient and bearing capacity, and shear strength is lower, and there are the bearing capacity low, warp big and anti-skidding poor stability scheduling problem in the dam foundation.

Secondly, the sand gravel permeability is strong, and whether the dam foundation seepage-proofing system is successful or not only influences the water storage benefit of the reservoir, but also is directly related to the safe application of the dam body and the reservoir.

Thirdly, the sand gravel has loose structure and poor uniformity of physical and mechanical properties, reliable downstream energy dissipation and scour prevention facilities are particularly important, and foundation scouring damage can be caused by improper treatment, so that the safety of the dam and the whole hub is threatened.

In the prior art, the patent documents relating to the construction of dams on deep covering layers are mainly: the utility model discloses a by the utility model patent of changjiang river survey planning and design research finial application (publication number is: CN102852121A) discloses the artifical composite foundation of building clay rock-fill dam on the deep overburden, and it includes bed rock (1), is located overburden (2) on bed rock (1), and the outside of inverted filter (4) is filter layer (5), and the outside of filter layer (5) is rock-fill (6), filter layer (5), inverted filter (4), heart wall (3) constitute the dam body, overburden (2) thickness be greater than 50 meters overburden (2) in have concrete apron (7), the dam body height be greater than 150 meters. The method can avoid the defects of large excavation work amount, increased diversion project scale, increased abandoned slag yard scale, prolonged project construction period, increased project investment and the like caused by a covering layer full-excavation scheme. According to the scheme, the impervious wall construction and the reinforcing grouting construction of the covering layer are carried out in the concrete cover plate gallery, dam body filling construction can be carried out synchronously, and the construction period is effectively shortened.

In addition, a utility model patent (publication number: CN105089012A) applied by the institute of survey and design, Guiyang, China Electricity-building group Limited company discloses a method for building a gravity dam on a deep covering layer and a structure of a concrete gravity dam on an arch, which comprises the steps of performing dynamic compaction treatment and consolidation grouting treatment on the deep covering layer (3), then arranging an arch-shaped concrete base (1) on the treated deep covering layer (3), arranging the arch ends of the arch-shaped concrete base (1) on bedrocks (4) on both sides, and then arranging the gravity dam (2) on the arch-shaped concrete base (1) to integrally pour the gravity dam (2) and the arch-shaped concrete base (1) without arranging structural joints. The scheme is mainly characterized in that two arch ends of an arch concrete base are supported on bedrocks at two banks, so that the structural stress is supported to the bedrocks at the two ends from an arch span, the arch base and an upper dam body are connected into a whole, and the requirement on anti-skidding stability is met by resistance provided by the base planes at the two ends and the arch ends at the bottom.

However, the above prior arts fail to consider the following problems: the dam foundation of the gravity dam has larger stress, and the deep sand gravel covering layer generally has low bearing capacity and strong permeability, does not meet the dam building requirement of the gravity dam, and can affect the stability and safety of the dam if the deep sand gravel covering layer is not well treated. Secondly, because the river valley is narrow, the flow rate of the river channel at the downstream of the stilling pool is high, and the sand gravel covering layer of the river bed is thick, the water flow can cause source-tracing scouring to damage the stability of the stilling pool, and the safety of a drainage gate (dam) is seriously threatened. In addition, because the concrete gravity dam has higher rigidity and certain settlement deformation, and the concrete impervious wall in the gravel foundation with sand and gravel is relatively flexible, if the connection treatment between the concrete impervious wall and the concrete impervious wall is not good, the seepage system of the dam foundation can be failed, and the safety of the dam can be endangered.

SUMMERY OF THE UTILITY MODEL

For overcoming the weak point of above-mentioned prior art, the utility model provides a build the structure of gravity dam on the deep sand ovum gravel overburden to solve on the deep sand ovum gravel layer that the deformation that gravity dam foundation exists is inhomogeneous, the bearing capacity is not enough, the permeability is strong, easily wash engineering difficult points such as destruction.

The utility model discloses a realize like this:

firstly, the utility model provides a method for building a gravity dam on a deep covering layer, which comprises dam foundation reinforcement, dam foundation seepage prevention, energy dissipation and scour prevention; wherein, the dam foundation reinforcement is to adopt the vibroflotation reinforcement technology to realize the reinforcement treatment of the deep sand gravel dam foundation; the dam foundation seepage prevention is realized by adopting a dam foundation seepage prevention technology based on flexible connection of a seepage prevention wall and a dam body; the energy dissipation scour protection adopts the vertical scour protection wall arranged at the lower part of the bottom plate of the stilling basin tail sill to solve the problem that the deep and thick sand gravel layer of the downstream riverbed is continuously brushed.

The structure for building the gravity dam on the deep covering layer constructed by the method comprises the gravity dam with a concrete structure, wherein a horizontal cover plate and a vertical downward-arranged impervious wall are arranged at the upstream of the gravity dam, the top of the impervious wall is connected with the bottom of the gravity dam, and the bottom of the impervious wall penetrates through the covering layer to a bedrock; a stilling pool, a stilling pool tail sill and a downstream apron are sequentially arranged at the downstream of the gravity dam; the lower part of the bottom plate of the stilling pool tail sill is provided with an impact wall which is vertically arranged downwards, the top of the impact wall is connected with the bottom plate of the stilling pool tail sill, and the bottom of the impact wall penetrates through the covering layer to the bedrock; vibroflotation piles are arranged above the covering layer, and a dense soil body is formed between the vibroflotation piles.

The utility model discloses one of the key technology adopts the vibroflotation reinforcement technique to realize that deep sand ovum gravel dam foundation consolidates and handles, improves the closely knit degree of dam foundation ovum gravel, reduces dam foundation inhomogeneity, improves dam foundation bearing capacity, and corresponding improvement dam foundation cling compound is stable. The utility model discloses do not excavate deep sand ovum gravel overburden, arrange the percussion pile that shakes on the overburden after simple clear basic list, through shaking the percussion pile and encrypt the loose sand ovum gravel dam foundation in upper strata.

As a preferable scheme, the vibroflotation piles are generally arranged in an equilateral triangle with the side length (a) of 2-3 m, the treatment range is that the building foundation is expanded outwards by 5-10 m, and the pile bottom penetrates through the upper loose sand-gravel covering layer to a depth not less than 1/2 of the maximum dam height. In the construction process, the arrangement of the vibroflotation piles can be properly adjusted according to actual conditions so as to achieve the required vibroflotation encryption effect. The construction of vibroflotation piles needs to adopt high-power hydraulic vibroflotation equipment, and parameters such as oil pressure, water pressure, vibration retention time and the like are determined according to field tests.

The second key technology of the utility model is dam foundation seepage prevention technology based on the flexible connection of the seepage prevention wall and the dam body. Namely, the lower part of the dam heel is provided with a vertical impervious wall, the top of the impervious wall is connected with the dam bottom, the wall bottom penetrates through the covering layer to the bedrock, and curtain grouting is carried out on the lower part of the bedrock. The key measure of the technology is that the impervious wall and the dam body are flexibly connected, and the water stopping adopts materials and types with better deformation performance, so that the problem of deformation coordination of the dam body and the foundation can be better solved. The concrete dam has higher rigidity and certain settlement deformation, while the concrete impervious wall in the gravel foundation with sand and gravel is relatively flexible, and if the connection treatment between the concrete impervious wall and the gravel foundation is not good, the seepage system of the dam foundation can be failed, so that the safety of the dam is endangered. This technique can solve the above problems.

As a preferable scheme, the anti-seepage wall is of a reinforced concrete structure type, the thickness of the anti-seepage wall is 0.6-1.2 m, and the anti-seepage wall is poured twice from bottom to top. And firstly, pouring the lower wall body, chiseling the wall top for 0.5m after the concrete strength reaches more than 80%, setting a key groove, and pouring the upper wall body to a designed elevation.

As a preferred scheme, the joint surface between the impervious wall and the dam bottom is in flexible connection, the contact joint surface is in an arc shape to meet the requirement of fine deformation, a rubber water stop is respectively arranged on the upstream surface and the top and is embedded in concrete of the impervious wall and the dam bottom, and other joint surfaces are tightly filled with joint filling materials such as asphalt hemp and the like.

The third key technology of the utility model is the energy dissipation and scour prevention technology on the sand gravel riverbed. Because the river valley is narrow, the flow rate of the river channel downstream of the stilling pool is high, and the sand gravel covering layer of the river bed is thick, the water flow can cause source-tracing scouring to damage the stability of the stilling pool, and the safety of a drainage gate (dam) is seriously threatened. The utility model discloses a establish perpendicular scour protection wall in stilling pool tail bank bottom plate lower part to solve the deep sand gravel layer of low reaches riverbed and constantly be drawn and brushed, draw out the back and influence stilling pool foundation safety, and then threaten the safe problem of whole pivot.

As a preferred scheme, the anti-impact wall is of a reinforced concrete structure, the thickness of the anti-impact wall is 0.6-1.0 m, the wall top is connected with the floor of the stilling pool in a nested mode, and the wall bottom penetrates through the gravel layer of sand eggs to the bedrock. The anti-impact wall is poured to be 1.5m above the elevation of the bottom of the stilling pool, after the concrete strength of the wall body reaches 80%, the top of the wall is chiseled by 0.5m, the wall is trimmed to form a joint which is connected with the bottom plate of the stilling pool in an embedded mode, and gaps between the top of the wall and the bottom plate of the stilling pool are filled with asphalt hemp.

Compared with the prior art, the utility model discloses effectively solve on the deep sand ovum gravel layer that the bearing capacity that gravity dam foundation exists is insufficient, warp too big, the permeability is strong, easily elutriate key problem such as destruction, have following beneficial effect:

(1) the dam foundation of the dam is only subjected to surface cleaning, and a deep covering layer is not excavated, so that excavation, supporting and drainage of a deep foundation pit of the foundation with strong water permeability are avoided.

(2) Greatly reduces the waste slag of engineering excavation, reduces the consumption of concrete, effectively solves the problems of land acquisition, water and soil conservation and the like of a waste slag field, and is favorable for protecting the ecological environment.

(3) The dam body pouring lifting speed is high, and flood fighting safety is guaranteed.

(4) The construction period is effectively shortened, and the project investment is saved.

Drawings

FIG. 1 is a longitudinal sectional view of the gravity dam and foundation of the present invention;

FIG. 2 is a rough drawing of flexible connection between the impervious wall and the dam bottom;

FIG. 3 is a schematic view showing the connection between the impact wall and the stilling pool bottom plate;

FIG. 4 is a plan view of a vibroflotation pile;

description of reference numerals: the method comprises the following steps of 1-impervious wall, 2-horizontal cover plate, 3-gravity dam, 4-absorption basin, 5-absorption basin tail bank, 6-impact prevention wall, 7-vibroflotation pile, 8-covering layer, 9-bedrock, 10-rubber water stopping I, 11-asphalt hemp thread I, 12-rubber water stopping II, 13-roughening key groove, 14-cast-in-place wall, 15-chiseling end, 16-asphalt hemp thread II, 17-downstream apron and 18-encrypted soil body.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted", "provided", "sleeved/connected", "connected", and the like are to be understood in a broad sense, such as "connected", which may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The utility model discloses an implement like this:

as shown in fig. 1, the gravity dam of the present invention is arranged along the water flow direction: the horizontal cover plate 2, the impervious wall 1, the gravity dam 3, the stilling pool 4, the stilling pool tail bank 5, the downstream apron 18, the vibroflotation pile 7 and the impact-proof wall 6 are arranged from the upstream to the downstream in sequence. The dam body structure of the gravity dam 3 is the same as that of a general gravity dam, and the details are not repeated.

As shown in fig. 1 and 4, the implementation process of the present invention includes the following steps: firstly, cleaning rotten wood, sundries and the like in the range of the dam foundation of the original riverbed, and cleaning turf on the upper surface of a bank slope, plant roots, domestic and industrial garbage and the like. Secondly, laying out pile points on the dam foundation of the riverbed covering layer, adopting a vibroflot to form a hole vibroflot pile 7, adding stone materials into the hole when the vibroflot forms the hole to the designed depth, conveying the hole to the bottom of the hole, and then starting vibroflot compaction construction; in order to ensure that the material adding amount of the encrypted pile body is 0.5m in the hole, the vibroflot is lifted by about 1.5-2.0 m each time.

The single pile adopts a continuous filling pile-making process. During pile making, continuous construction is required, the encryption starts from the bottom of a hole, the pile is upwards section by section, and vibration leakage cannot occur in the middle. When the specified encryption oil pressure and the specified vibration duration are reached, the vibroflot is lifted up to continue to encrypt the next section, and the encryption length of each section is in accordance with the requirement. And repeating the steps from bottom to top until the pile top is encrypted to the elevation required by the design, and then performing the next pile construction.

As shown in figure 1, in order to save the engineering investment, for the dam foundation covering layer 8, the vibroflotation compaction depth h1 is controlled according to the control that the vibroflotation compaction depth h is not less than half of the dam height h0, namely h1 is not less than 0.5h0, and if the residual covering layer thickness h2 is less than 5m, the covering layer 8 is fully vibroflotation compacted, namely the pile bottom of the vibroflotation pile 7 extends to the bedrock 9. The specific vibroflotation encryption depth is properly adjusted according to the geological condition and vibroflotation test detection result.

As shown in fig. 1 and 2, when the impervious wall 1 is constructed, a reinforced concrete structure is adopted, and pouring is performed twice from bottom to top. The lower wall body is poured to be 1m below the elevation of the dam bottom, after the concrete strength reaches more than 80%, the wall top is chiseled off by 0.5m, a chiseled key groove 13 is arranged, and then the upper wall body is poured to reach the designed elevation.

As shown in fig. 2, the seam surface between the cast-in-place wall 14 of the impervious wall 1 and the bottom plate of the gravity dam 3 is flexibly connected, the contact surface is arc-shaped to adapt to the requirement of slight deformation, a rubber water stop first 10 is arranged on the upstream surface, a rubber water stop second 12 is arranged on the top, the rubber water stop first 10 and the rubber water stop second 12 are required to be embedded in the concrete of the cast-in-place wall 14 of the impervious wall 1 and the bottom plate of the gravity dam 3, and the rest seams are filled and compacted by adopting an asphalt hemp thread first 11 as a joint filling material.

As shown in fig. 3, when constructing the joint of the bottom plate of the impact wall 6 and the stilling pool 5, the impact wall 6 is poured firstly to about 1.5m above the height of the bottom of the stilling pool 4, after the strength of the concrete of the wall body reaches more than 80%, the chiseling end head 15 of the wall top is chiseled, the joint is formed by trimming to be nested and connected with the bottom plate of the stilling pool 4, the concrete of the stilling pool 5 is poured, and the space between the wall top and the concrete of the bottom plate of the stilling pool 4 is filled with asphalt hemp two 16.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments or portions thereof without departing from the spirit and scope of the invention.

Claims (4)

1. The utility model provides a structure of building gravity dam on deep overburden which characterized in that: the gravity dam comprises a gravity dam (3) with a concrete structure, wherein a horizontal cover plate (2) and a vertical downward-arranged impervious wall (1) are arranged at the upstream of the gravity dam (3), the top of the impervious wall (1) is connected with the bottom of the gravity dam (3), and the bottom of the impervious wall (1) penetrates through a covering layer (8) to a bedrock (9); a stilling pool (4), a stilling pool tail sill (5) and a downstream apron (17) are sequentially arranged at the downstream of the gravity dam (3); the lower part of the bottom plate of the stilling pool tail sill (5) is provided with a vertically downward anti-impact wall (6), the top of the anti-impact wall (6) is connected with the bottom plate of the stilling pool tail sill (5), and the bottom of the anti-impact wall (6) penetrates through the covering layer (8) to the bedrock (9); vibroflotation piles (7) are arranged above the covering layer (8), and a dense soil body (18) is formed between the vibroflotation piles (7).

2. The structure of building a gravity dam on a deep overburden as recited in claim 1, wherein: and a grouting curtain is arranged at the lower part of the bedrock (9).

3. The structure of building a gravity dam on a deep overburden as recited in claim 1, wherein: the anti-seepage wall (1) adopts a cast-in-place wall body (14), the seam surface between the cast-in-place wall body (14) and the bottom plate of the gravity dam (3) adopts flexible connection, the contact surface is arc-shaped, one rubber water stop I (10) is arranged on the upstream surface, one rubber water stop II (12) is arranged on the top, the rubber water stop I (10) and the rubber water stop II (12) are embedded in the concrete of the bottom plates of the cast-in-place wall body (14) and the gravity dam (3), and other gaps are densely filled with a gap filling material of an asphalt hemp thread I (11).

4. The structure of building a gravity dam on a deep overburden as recited in claim 1, wherein: and asphalt hemp threads (16) are filled between the wall top of the impact-proof wall (6) and the bottom plate concrete of the absorption basin (4).

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