CN112854144A

CN112854144A - Construction structure of earth-rock dam on deep sludge layer and construction method thereof

Info

Publication number: CN112854144A
Application number: CN202110266752.2A
Authority: CN
Inventors: 刘元勋; 陈松滨; 王海建; 范穗兴; 韩小妹
Original assignee: China Water Resources Pearl River Planning Surverying & Designing Co ltd
Current assignee: China Water Resources Pearl River Planning Surverying & Designing Co ltd
Priority date: 2021-03-11
Filing date: 2021-03-11
Publication date: 2021-05-28

Abstract

The invention discloses a construction structure of an earth-rock dam on a deep sludge layer and a construction method thereof, wherein the structure comprises an upstream dike and a downstream dike, dike inner side reverse filters formed by throwing and filling reverse filter materials are respectively arranged on the inner sides of the upstream dike and the downstream dike, an underwater throwing and filling dam body is arranged between the upstream dike inner side reverse filters and the downstream dike, and the underwater throwing and filling dam body is a structure formed by throwing and filling medium coarse sand and is filled out from a water surface to a flood height; plastic drainage plates are arranged in the underwater filling dam body and the dam foundation sludge layer for vacuum preloading and vibroflotation encryption treatment; and plastic concrete impervious walls are arranged on the underwater filling dam body and the dam foundation silt layer, and a dam foundation curtain is arranged on the bedrock below the plastic concrete impervious walls. By adopting the structure of the invention, foundation pit excavation is not needed, cofferdam air-tight water pumping is not needed, deep sludge layers of riverbeds are not excavated, and the sludge is used as a part of a dam foundation after in-situ consolidation and drainage combined with vibroflotation gravel pile treatment, so that the construction process is optimized, and a large amount of filling materials are saved.

Description

Construction structure of earth-rock dam on deep sludge layer and construction method thereof

Technical Field

The invention relates to a construction structure of an earth-rock dam on a deep sludge layer, belonging to the technical field of hydraulic and hydroelectric engineering.

Background

In the middle and lower river areas, soft foundation strata such as silt and the like are widely distributed, are generally in a soft plastic or flow plastic shape, have the characteristics of low water content, high porosity and easiness in compression deformation, and are not suitable for being directly used as the foundation of a building. On this type of foundation, the construction of hydraulic buildings such as earth-rock dams and the like usually requires the construction of a cofferdam first to form a foundation pit, and then a sludge layer is dug in the foundation pit and the dam is filled.

As in the prior art, the north engineering limited of medium cross roads and bridges; the invention patent CN108570996A of China railway bridge construction Limited company discloses a cofferdam construction method under the condition of shallow water sludge, and double rows of steel pipe piles positioned at the periphery of a bridge section to be built are formed; on the opposite surfaces of the two rows of steel pipe piles, the bamboo chip net is inserted to the bottom by adhering to the outer wall of the steel pipe and is fixed on the steel pipe; vertically inserting the grid geotextile to the bottom along the outer wall of the steel pipe on the opposite surfaces of the two rows of steel pipe piles, and fixing the grid geotextile on the steel pipe; the steel pipes of the two rows of steel pipe piles are pulled up one by adopting a steel wire rope pair zipper, and for each row of steel pipe piles, longitudinal connecting steel pipes are adopted at the outer sides of the steel pipe piles to connect the steel pipe piles; after the dam is built, water in the cofferdam is pumped out by a water pump, and the seepage position of the dam body in the water pumping process or after water pumping is blocked in time; the sludge in the cofferdam is cleaned, and a sand cushion and the coarse residue soil are paved for treatment.

However, the construction method in the prior art needs to treat a large amount of sludge, solidify the sludge and then discard the solidified sludge, and the cost is high. When the sludge layer is thick, a deep foundation pit is formed, the stability is poor, and the supporting engineering quantity is huge. A large amount of waste soil needs to occupy a large area as a waste slag field and corresponding water conservation measures, thereby wasting precious land resources, having low efficiency and high investment, and not meeting the requirements of energy conservation, emission reduction and environmental protection. Therefore, the existing technology for building hydraulic buildings such as earth-rock dams on the deep sludge layer is not suitable for the requirements of the current social and economic development on ecological environment and engineering construction efficiency, and needs to be further improved.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide an earth and rockfill dam construction structure and a construction method thereof, which can be directly constructed underwater without a foundation pit and a support in the traditional sense and without excavating a deep silt layer.

The invention is realized by the following steps:

a construction structure of an earth-rock dam on a deep sludge layer comprises an upstream dike and a downstream dike, wherein inner side reverse filters formed by casting and filling reverse filters are respectively arranged on the inner sides of the upstream dike and the downstream dike, an underwater cast-filling dam body is arranged between the inner side reverse filters of the upstream dike and the downstream dike, and the underwater cast-filling dam body is a structure formed by casting and filling materials including medium coarse sand and fills the water surface to a flood height; plastic drainage plates are arranged in the underwater filling dam body and the dam foundation sludge layer for vacuum preloading and vibroflotation encryption treatment; and plastic concrete impervious walls are arranged on the underwater filling dam body and the dam foundation silt layer, and a dam foundation curtain is arranged on the bedrock below the plastic concrete impervious walls.

Wherein, the upper dam impervious core wall of the underwater throwing filling dam body adopts a clay core wall, and a high-plasticity soil transition area is adopted between the plastic concrete impervious wall and the clay core wall; an upstream dam shell and a downstream dam shell are respectively arranged at the upstream side and the downstream side of the impervious core wall of the upper dam body; an upstream slope protection and a downstream drainage body are respectively arranged on the slope surfaces of the upstream dam shell and the downstream dam shell.

Furthermore, vibroflotation gravel piles are arranged at intervals on the plastic drainage plates and are used for vibroflotation treatment of the underwater cast-fill dam body and the dam foundation sludge layer.

The construction method of the structure comprises the following steps:

s1, constructing an upstream dike and a downstream dike by bank side throwing and filling to occupy the river bed; the prop-dam slope toe is positioned outside the extending line of the dam slope, the top width is 6-10 m, and the upstream slope and the downstream slope are 1: 2-1: 2.5;

s2, filling materials from the upstream dike and the downstream dike to the middle of the riverbed respectively, and throwing and filling reverse filter materials on the inner sides of the upstream dike and the downstream dike respectively to form a dike inner reverse filter body with the horizontal width not less than 5 m; then, continuously throwing and filling coarse sand between the upstream and downstream dike inner side reverse filters, and filling the sand out of the water surface to a flood height to form an underwater throwing and filling dam body;

s3, paving and filling the medium coarse sand cushion layer again on the construction platform formed by the underwater cast-fill dam body to serve as a drainage channel;

s4, constructing a plastic drainage plate, wherein the lower part of the plastic drainage plate extends to the bottom of the sludge layer;

s5, constructing a drainage blind ditch;

s6, arranging vibro-replacement gravel piles at intervals on the plastic drainage plate, performing vibro-replacement treatment on the lower throwing filling body and the sludge layer to further drain and solidify the sludge layer, and simultaneously encrypting the lower throwing filling body; the dam body and the dam foundation at the lower part of the earth-rock dam are constructed by adopting an underwater foundation-pit-free method;

s7, constructing a plastic concrete impervious wall and a dam foundation curtain in the middle of the lower dam body;

s8, excavating a part of the preloading filling material on the top downstream area of the plastic concrete impervious wall, replacing the preloading filling material with a high-plastic soil transition area and a clay core wall, and finishing layered rolling and filling;

and S9, constructing the upper dam body.

Compared with the prior art, the invention has the following prominent substantive characteristics and remarkable progress:

firstly, by adopting the structure of the invention, foundation pit excavation is not needed, cofferdam air-tight water pumping is not needed, a deep sludge layer of a riverbed is not excavated, and the sludge is used as a part of a dam foundation after in-situ consolidation and drainage combined with vibroflotation gravel pile treatment, thereby optimizing the construction process and saving a large amount of filling materials. Secondly, the structure of the invention does not need to dig out a deep sludge layer, thereby avoiding the problems of high sludge solidification treatment cost and the like caused by digging the deep sludge layer, reducing land collection of a solidification field and a waste residue field, and being beneficial to ecological environment protection and water and soil conservation. Moreover, the structure of the invention can optimize the construction process, avoid deep foundation pit support and is beneficial to the safety of construction sites.

The invention can also save land acquisition and related water conservation and environmental protection measures, and obviously save construction period and engineering investment.

Drawings

FIG. 1 is a schematic structural diagram of an earth-rock dam body of the invention;

FIG. 2 is a schematic view of the construction of a plastic drainage plate;

FIG. 3 is a schematic view of vibro-replacement stone column construction;

FIG. 4 is a schematic view of a plastic drain board arrangement;

FIG. 5 is a schematic view of a vibro-replacement stone column arrangement;

FIG. 6 is a schematic view of a transition zone of high plasticity soil.

Description of reference numerals: 1-upstream dike, 2-downstream dike, 3-dike inside reverse filter, 4-underwater cast-fill dam body, 5-medium coarse sand cushion layer, 6-plastic drainage plate, 7-plastic concrete impervious wall, 8-dam foundation curtain, 9-high-plastic soil transition region, 10-upper dam body impervious core wall, 11-upstream dam shell, 12-downstream dam shell, 13-upstream slope protection, 14-downstream drainage body, 15-silt layer, 16-bedrock, 17-drainage blind ditch and 18-gravel pile.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," "sleeved/connected," "connected," and the like are to be construed broadly, e.g., "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 meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The invention is implemented as follows:

according to the structure, sludge in a riverbed does not need to be dug and removed, block stones are directly dumped and filled in the riverbed to form the upstream dike 1 and the downstream dike 2, dam materials such as coarse sand and the like are dumped and filled underwater in the middle of the dike to form a construction platform after the dikes are exposed out of the water surface, the sludge is subjected to field drainage, consolidation and encryption treatment on the platform to form a lower dam body and a dam foundation, then the lower dam body and the dam foundation are subjected to seepage-proofing treatment, and the filling construction of the upper dam body is completed according to a conventional mode.

The detailed technical scheme of the invention is as follows:

and (3) respectively throwing and filling rock-fill materials at slope toe positions of an upper dam and a lower dam designed on a river bed to form a dike, then throwing and filling medium coarse sand materials between the upper dike and the lower dike, and filling the water surface to a flood height to form the overwater construction platform. And (3) inserting a plastic drainage plate 6 into the dam foundation sludge layer 15 on the platform, performing vacuum preloading to promote the lower sludge to be solidified and drained, and then performing vibroflotation and encryption treatment on the lower dam body filler and the dam foundation sludge layer 15 to meet the compactness and bearing requirements of the dam.

The prop dam is arranged outside the boundary between the dam slope extension line and the dam foundation of the earth-rock dam and serves as a temporary construction channel to provide a still water construction condition for underwater filling of a dam body and form a permanent press platform and a protective body of a dam toe in the later period. The prop dam is preferably filled with stone with good quality. The elevation of the prop dam top is higher than the flood height (h) by more than 0.5m, the width of the prop dam top is generally 6-10 m, and the upstream slope and the downstream slope are 1: 2-1: 2.5. The inside of the dike is filled with the filter material, and the horizontal thickness of the filter material is generally more than 5 m. The consolidation and drainage of the silt generally adopt PVC plastic drainage plates, the interval row spacing (a) can be arranged according to 1m, the treatment range is a dam foundation silt layer 15 between dikes, and the exposed length of the top of the dam foundation silt layer is 0.5 m. As a preferred scheme, a graded broken stone drainage blind ditch 17 is arranged on a construction platform, vacuum preloading is carried out on the lower sludge layer 15, and water drained by the vacuum preloading is drained downstream through the drainage blind ditch 17.

After the dam foundation sludge is subjected to vacuum preloading and preliminary drainage consolidation treatment, vibroflotation gravel piles 18 are arranged on a construction platform, vibroflotation compaction is carried out on the underwater throwing filler and the sludge layer 15 foundation, and the gravel piles can be used as drainage channels. The gravel piles 18 are arranged at intervals on the plastic drainage plates 6, the spacing is generally 3m, and the gravel piles can be adjusted according to actual conditions.

Underwater filling and silt layer 15 foundation vibroflotation and encryption processing, and after the compactness and the dam foundation bearing requirements required by design are met through detection, the dam body and the dam foundation at the lower part of the earth-rock dam are constructed by adopting an underwater foundation-pit-free technology.

And the second step, constructing an upper dam body and an anti-seepage body. The upper dam body is conventionally used without further details. The seepage-proofing body consists of a dam body seepage-proofing body and the seepage-proofing bodies of the lower dam body and the dam foundation. Wherein, the lower dam body and the dam foundation of the silt layer 15 adopt plastic concrete impervious walls 7, and the impervious bedrock adopts curtain grouting to form a dam foundation curtain 8.

The designed compressive strength of the plastic concrete core wall is generally not lower than 3.0MPa, the tensile strength is not lower than 0.5MPa, the elastic modulus is 500-800 MPa, and the permeability coefficient is less than 1 multiplied by 10^-7cm/s。

As a preferred scheme, the upper dam body seepage-proofing adopts a clay core wall, and high-plasticity soil is filled at the joint of the core wall and the plastic concrete seepage-proofing wall 7 for transition to form a high-plasticity soil transition area 9. Wherein, the wrapping area formed by the high-plasticity soil on the head part of the impervious wall is more than 5 m.

The construction steps of the present invention will be described in detail below with reference to the accompanying drawings:

first, as shown in figure 1, upstream dike 1 and downstream dike 2 are constructed by bank side throwing and filling to advance into the river bed, and the dike top elevation is determined according to the flood water level plus super height. The prop bank toe is positioned outside the extending line of the dam slope, the top width is generally 6-10 m according to the construction requirement, and the upstream slope and the downstream slope are 1: 2-1: 2.5.

Secondly, filling materials from the upstream dike and the downstream dike to the middle of the river bed respectively, and throwing and filling reverse filter materials on the inner sides of the upstream dike 1 and the downstream dike 2 respectively to form a dike inner side reverse filter body 3, wherein the horizontal width is not less than 5 m. And then, continuously throwing and filling medium coarse sand with a certain grading requirement between the upstream and downstream reverse filters 3, and filling the medium coarse sand out of the water surface to a flood height to form an underwater throwing and filling dam body 4.

As shown in fig. 2, the medium coarse sand cushion 5 is paved and filled again on the construction platform formed by the underwater riprap dam body 4 to be used as a drainage channel.

As shown in FIGS. 2 and 3, the plastic drainage plate 6 is constructed, and the lower part of the plastic drainage plate 6 extends to the bottom of the sludge layer 15.

As shown in fig. 2, a drainage blind ditch 17 is constructed.

As shown in fig. 3 and 5, after the drainage consolidation of the lower sludge layer reaches the design requirement, vibroflotation gravel piles 18 are arranged at intervals on the plastic drainage plate 6, and vibroflotation treatment is performed on the lower throwing filling body 4 and the sludge layer 15, so that the sludge layer 15 is further drained and consolidated, and meanwhile, the throwing filling body 4 is encrypted, and the compactness and the dam foundation bearing requirement required by the design are met. And finally, completing construction of the dam body and the dam foundation at the lower part of the earth-rock dam by adopting an underwater foundation-pit-free method.

As shown in figures 1 and 6, a plastic concrete impervious wall 7 and a dam foundation curtain 8 are constructed in the middle of the lower dam body.

As shown in figure 6, in the top downstream area of the impervious wall, a part of the preloading filling material is dug out respectively, and the high plasticity soil transition area 9 and the clay core wall 10 are replaced and filled, and layered rolling and filling are completed.

As shown in FIG. 6, the thickness of the wrapping area formed by the high-plasticity soil transition area 9 on the impervious wall is more than or equal to 5 m.

After the above-mentioned process is accomplished, begin to construct upper portion dam body, include: the construction mode of the upstream dam shell 11, the downstream dam shell 12, the upper clay core wall 10, the upstream revetment 13 and the downstream drainage body 14 is a conventional mode and is not described in detail.

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 various changes in the embodiments and/or modifications of the invention can be made, and equivalents and modifications of some features of the invention can be made without departing from the spirit and scope of the invention.

Claims

1. A construction structure of an earth-rock dam on a deep sludge layer is characterized in that: the dam comprises an upstream dike (1) and a downstream dike (2), wherein inner side reverse filters (3) formed by throwing and filling reverse filter materials are respectively arranged on the inner sides of the upstream dike (1) and the downstream dike (2), an underwater throwing and filling dam body (4) is arranged between the inner side reverse filters (3) of the upstream dike and the downstream dike, the underwater throwing and filling dam body (4) is a structure formed by throwing and filling materials including medium coarse sand, and the dam body is filled out of a water surface to a flood height; plastic drainage plates (6) are arranged in the underwater filling dam body (4) and the dam foundation silt layer (15) for vacuum preloading and vibroflotation encryption treatment; the underwater filling dam body (4) and the dam foundation silt layer (15) are provided with a plastic concrete impervious wall (7), and a dam foundation curtain (8) is arranged on a foundation rock (16) below the plastic concrete impervious wall (7).

2. The construction structure of an earth and rockfill dam on a deep sludge layer according to claim 1, wherein: the upper dam impervious core wall (10) of the underwater throwing filling dam body (4) adopts a clay core wall, and a high-plasticity soil transition area (9) is adopted between the plastic concrete impervious wall (7) and the clay core wall.

3. The construction structure of an earth and rockfill dam on a deep sludge layer according to claim 1, wherein: an upstream dam shell (11) and a downstream dam shell (12) are respectively arranged on the upstream side and the downstream side of the upper dam body impervious core wall (10).

4. The construction structure of an earth and rockfill dam on a deep sludge layer according to claim 1, wherein: an upstream protection slope (13) and a downstream drainage body (14) are respectively arranged on the slope surfaces of the upstream dam shell (11) and the downstream dam shell (12).

5. The construction structure of an earth and rockfill dam on a deep sludge layer according to claim 1, wherein: and vibro-replacement gravel piles (18) are arranged at intervals on the plastic drainage plates (6) and are used for vibro-replacement and encryption treatment of the underwater filling dam body (4) and the dam foundation silt layer (15).

6. A construction method of a construction structure of an earth-rock dam on a deep sludge layer as claimed in any one of claims 1 to 5, comprising the steps of:

s1, constructing an upstream dike (1) and a downstream dike (2) by bank side throwing and filling to occupy the river bed; the prop-dam slope toe is positioned outside the extending line of the dam slope, the top width is 6-10 m, and the upstream slope and the downstream slope are 1: 2-1: 2.5;

s2, filling materials from the upstream dike (1) and the downstream dike (2) to the middle of the river bed respectively, firstly, respectively throwing and filling filter materials on the inner sides of the upstream dike (1) and the downstream dike (2) to form a dike inner side filter body (3), wherein the horizontal width is not less than 5 m; then, continuously throwing and filling coarse sand between the upstream and downstream dike inner side inverted filter bodies (3), and filling the sand out of the water surface to a flood height to form an underwater throwing and filling dam body (4);

s3, paving and filling the medium coarse sand cushion layer (5) on the construction platform formed by the underwater cast-fill dam body (4) again to serve as a drainage channel;

s4, constructing a plastic drainage plate (6), wherein the lower part of the plastic drainage plate (6) extends to the bottom of the sludge layer (15);

s5, constructing a drainage blind ditch (17);

s6, arranging vibroflotation gravel piles (18) at intervals on the plastic drainage plate (6), performing vibroflotation treatment on the lower throwing filling body (4) and the sludge layer (15), further draining and solidifying the sludge layer (15), and simultaneously encrypting the lower throwing filling body (4); the dam body and the dam foundation at the lower part of the earth-rock dam are constructed by adopting an underwater foundation-pit-free method;

s7, constructing a plastic concrete impervious wall (7) and a dam foundation curtain (8) in the middle of the lower dam body;

s8, digging out a part of the preloading filling material in the top downstream area of the plastic concrete impervious wall (7), replacing the preloading filling material with a high-plastic soil transition area (9) and a clay core wall (10), and finishing layered rolling and filling;

and S9, constructing the upper dam body.