阅读说明：本技术 一种灌注式防渗心墙土石坝的构筑方法及其结构 (Construction method and structure of pouring type impervious core earth-rock dam ) 是由 彭春雷 陈松滨 范穗兴 王海建 宾斌 丁剑波 黄晓倩 徐苏晨 于 2020-08-30 设计创作，主要内容包括：本发明公开了一种灌注式防渗心墙土石坝的构筑方法及其结构,该方法由水下坝体填筑及坝基处理方法、灌注式防渗心墙的形成方法、坝料选择与控制方法三部分组成,大坝结构分为上、下两部分坝体及防渗体系。下部坝体直接在水下抛填坝料振冲加密完成。上部坝体采用库区砂砾、软岩、砾石土、风化料及开挖渣料分层碾压完成,并采用试验结合计算分析、填筑指标及施工参数的综合方法进行压实控制。防渗体系由脉动灌浆技术在坝体及覆盖层形成的防渗心墙连接基岩帷幕组成。本发明拓展了土石坝适用范围,实现水下直接抛填施工,有效缩短工期,节省围堰填筑、堰体防渗、基坑开挖、基坑抽水,节省料场、渣场征地及相关水保、环保措施。(The invention discloses a construction method and a structure of a pouring type impervious core earth-rock dam. And directly throwing filling dam materials under water to perform vibroflotation and encryption on the lower dam body. The upper dam body is formed by layering and rolling of reservoir gravel, soft rock, gravel soil, weathered materials and excavation slag materials, and compaction control is performed by adopting a comprehensive method of test combined calculation analysis, filling indexes and construction parameters. The seepage-proofing system is formed by connecting a basement rock curtain with a seepage-proofing core wall formed on a dam body and a covering layer by a pulsating grouting technology. The invention expands the application range of the earth-rock dam, realizes underwater direct throwing filling construction, effectively shortens the construction period, saves cofferdam filling, weir body seepage prevention, foundation pit excavation and foundation pit water pumping, and saves stock ground, slag yard land acquisition and related water conservation and environmental protection measures.)

1. A construction method of a pouring type impervious core earth-rock dam is characterized by comprising the following steps: the method designs the earth-rock dam into an upper dam body and a lower dam body and an anti-seepage system, and consists of three parts, namely an underwater dam body filling and dam foundation processing method, a forming method of a pouring type anti-seepage core wall and a dam material selecting and controlling method; the underwater dam filling and dam foundation processing method is that dam materials are directly filled underwater, and the filling and dam foundation covering layer is subjected to vibroflotation encryption processing to form a lower dam body; the method for forming the pouring type impervious core wall comprises the steps of adopting pulse grouting to form the impervious core wall on a dam body and a dam foundation covering layer, adopting curtain grouting to form an impervious curtain to bedrock, and forming an impervious system of the earth-rock dam together; the dam material selection and control method is characterized in that the upper dam body filler is widely selected from sand gravel, soft rock, gravel soil, weathered materials and stone slag materials excavated by buildings in a reservoir area, and compaction control is performed by adopting a comprehensive method of test combined calculation analysis, filling indexes and construction parameters.

2. The method for constructing a poured type impermeable core earth-rock dam as claimed in claim 1, wherein: directly throwing and filling dam materials under water for the lower dam body and completing vibroflotation and compaction, namely directly throwing and filling piled stones at the upstream and downstream slope feet to form a dike, throwing and filling sand gravel or stone slag materials with a certain gradation between the upstream and downstream dikes, and filling the dike out of the water surface to a flood height to form an overwater construction platform; and (3) adopting vibroflotation for the filled dam body and the dam foundation on the platform to ensure that the dam body and the dam foundation reach the required compactness, thereby realizing underwater dam building.

3. The method for constructing a poured type impermeable core earth-rock dam as claimed in claim 2, wherein: the berm is arranged outside the junction of the extending line of the dam slope of the earth-rock dam and the dam foundation, and is used as a temporary construction channel to provide enclosure for underwater filling dam bodies and form a permanent pressing platform and a protective body of the dam toe in the later period; the width of the prop dyke top is 6-10 m, and the upstream slope and the downstream slope are 1: 2-1: 2.5; the inside of the prop bank is filled with a reverse filter material; the saturated compressive strength of the stone material of the dike is not less than 30Mpa, the softening coefficient is not less than 0.75, and the grain diameter is 200 mm-1000 mm.

4. The method for constructing a poured type impermeable core earth-rock dam as claimed in claim 2, wherein: when the vibroflotation is used for compaction, the piles are arranged according to equilateral triangles with the spacing of 2-3 m, and sand gravel and stone slag materials which are thrown and filled underwater between the dikes and loose dam foundation covering layers are treated.

5. The method for constructing a poured type impermeable core earth-rock dam as claimed in claim 1, wherein: the pulsating grouting is characterized in that drilling holes are arranged in the middle of a dam body, the rows are arranged in 2-5 rows according to the dam height, the effective thickness D of the formed impervious core wall is larger than H/15, H is the maximum water retaining head, and the permeability coefficient is smaller than 5 multiplied by 10^-6cm/s, and the elastic modulus is 200-1000 MPa; the pulsating grouting impervious core wall is implemented by an upper project and a lower project, wherein the first project is a dam body and a dam foundation below the flood height, and the second project is a dam body above the flood height; the grouting slurry is clay cement paste slurry, and the fluidity of the grouting slurry is 60-120 mm; the slurry mixing proportion calculated by mass is as follows: clay: additive: water is 100: 50-200: 2-5: 140-250; the pulsating grouting is performed by sections from bottom to top, each section is 0.5-1.0 m, and the diffusion radius of the grout is 1.0-1.5 m.

6. The method for constructing a poured type impermeable core earth-rock dam as claimed in claim 5, wherein: the additive is formed by mixing one or more of sodium sulfate, sodium metaaluminate, sodium metasilicate, cellulose, vegetable gum and polyacrylamide; the specific gravity of the paste slurry is 1.5g/cm³～1.65g/cm³The initial setting time is 2-6 h; and (3) grouting by using a special plunger pump, wherein the pumping frequency is 6-12 times per minute, and the pumping quantity of a single cylinder per time is more than 5L.

7. The method for constructing a poured type impermeable core earth-rock dam as claimed in claim 1, wherein: the dam material selection and control means that the upper dam body filler is widely selected from sand gravel, soft rock, gravel soil, weathered materials and stone slag materials excavated by buildings in a reservoir area, and after being compacted by adopting specific construction parameters, compaction control indexes corresponding to the weathered materials, the gravel soil, the sand gravel and hard rock excavation materials are selected as a comprehensive compaction control standard; carrying out compaction control by combining a field test with a comprehensive method including calculation analysis, filling indexes and construction parameters; wherein, for weathered materials and gravel soil, the permeability coefficient is not controlled, and only the gravel content is controlled, wherein the gravel content is between 40 and 60 percent; for the sand-gravel material, river bed materials in a reservoir area are selected, the maximum grain diameter Dmax is less than 200mm, and the content of organic matters and impurities is less than 5%; soft rock excavation slag materials refer to weathered materials and gravel soil standards; the maximum grain size Dmax of the slag material for hard rock excavation is less than 500 mm; the rolling construction parameters are that the paving thickness of weathered materials, gravel soil and sand gravel is not more than 400mm, the paving thickness of hard rock excavating materials is not more than 800mm, and the maximum grain size of dam materials is not more than 2/3 of the paving thickness; the same dam material is adopted as much as possible for paving and filling the same layer, the rolling times of the dam material are strictly controlled to be more than 10 times generally, the weight of a rolling machine is less than 25t, and the water doping amount is 5-15% according to the difference of the dam material.

8. A poured core earth and rockfill dam structure constructed by the method of any one of claims 1 to 7, wherein: the dam comprises an upstream dike (1) and a downstream dike (2), dike inner side reverse filters (18) formed by throwing and filling reverse filters are respectively arranged on the inner sides of the upstream dike (1) and the downstream dike (2), an underwater throwing and filling dam body (3) is arranged between the dike inner side reverse filters (18) on the upstream and the downstream dikes, the underwater throwing and filling dam body (3) is formed by throwing and filling sand gravel and stone slag materials, and the dam body is filled out of a water surface to a flood height; arranging vibroflotation packing piles (4) in the underwater throwing filling dam body (3) and the dam foundation covering layer (12) for packing; a lower dam impervious core wall (5) is arranged in the middle of the underwater cast-fill dam (3), a dam foundation curtain (6) is arranged below the lower dam impervious core wall (5), an upper dam impervious core wall (9) is arranged above the lower dam impervious core wall (5), and an upstream dam shell (7) and a downstream dam shell (8) are respectively arranged on the upstream side and the downstream side of the upper dam impervious core wall (9); and an upstream slope protection (10) and a downstream drainage body (11) are respectively arranged on the slopes of the upstream dam shell (7) and the downstream dam shell (8).

9. The poured impermeable core earth-rock dam structure of claim 8, wherein: the lower dam impervious core wall (5) and the upper dam impervious core wall (9) are structures formed by adopting pulsating grouting on the underwater filling dam (3) and the dam foundation covering layer (12); the bottom of the grouting hole of the upper dam impervious core wall (9) extends into the lower dam impervious core wall (5) by 3-5 m to form a core wall lap joint area (17).

10. The poured impermeable core earth-rock dam structure of claim 8, wherein: 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; the horizontal width of the inside reverse filter (18) of the dike is more than 5 m.

Technical Field

The invention relates to a construction method and a structure of a pouring type impervious core earth-rock dam, belonging to the technical field of hydraulic and hydroelectric engineering.

Background

As the oldest dam type, the earth-rock dam is widely applied to water conservancy and hydropower engineering. With the development of economic society, the ecological environment protection is increasingly important, and the following problems are highlighted in the traditional earth-rock dam structure:

firstly, the dam body of the traditional earth-rock dam is filled with compactness (cohesive soil), relative density (gravel) or porosity (rockfill) as the only design control index, the requirement on dam materials is high, more cohesive soil materials are used, a stock yard with huge reserves needs to be searched, a waste disposal yard needs to be arranged, a large amount of cultivated land, forest land and the like are occupied, and the local ecological environment is greatly influenced.

Secondly, the construction of the earth-rock dam generally needs to arrange upstream and downstream cofferdams to form a foundation pit, excavate a covering layer, perform dam foundation treatment and flood control body filling, and then perform dam body construction. More time is consumed in cofferdam filling and dam foundation treatment, the time for filling the flood control body is less, the construction organization difficulty is higher, and a longer construction period is generally required.

Moreover, earth-rock dams generally adopt clay, asphalt concrete and other types in terms of selection of anti-seepage bodies.

For example, in the prior art, the invention patent with publication number CN106368177A of the institute of survey and design, ltd, of the institute of electrical and capital, china, discloses a composite high earth-rock dam. The composite high earth-rock dam comprises an asphalt core wall, an upstream rockfill area, an upstream transition layer, an upstream reverse filter layer and an upstream soil core wall which are sequentially arranged on the upstream side of the asphalt core wall along the water flow direction, and a downstream soil core wall, a downstream reverse filter layer, a downstream transition layer and a downstream rockfill area which are sequentially arranged on the downstream side of the asphalt core wall along the water flow direction. According to the scheme, the upstream soil core wall and the downstream soil core wall are respectively arranged on the upstream side and the downstream side of the asphalt core wall to form a composite core wall structure, so that the using amount of impermeable earth materials and asphalt materials can be reduced on the premise of ensuring the stability and safety of the dam body.

For another example, an invention patent with publication number CN1807763 applied by the scientific research institute of northeast survey design and research of reclaimed water, ltd discloses a construction method of a vibrating asphalt concrete impervious core wall of an earth and rock dam, comprising the following steps: a. laying a template: the template comprises a sliding template or an assembled movable template; b. laying high-temperature-resistant non-woven fabrics; c. paving transition materials and rolling the transition materials; d. paving asphalt concrete: pouring the vibrating asphalt mixture into the template and using a knife-plate vibrator to make the asphalt mixture vibrate tightly, wherein the vibrating asphalt mixture comprises the following raw materials: aggregate, mineral powder and asphalt; e. sliding the template or removing the template; f. and (5) maintaining the temperature. The scheme can be constructed under the temperature condition of more than 25 ℃ below zero without being limited by the temperature condition. The vibrating asphalt concrete adopted in the construction of the impervious core wall has good homogeneity and seepage-proofing performance, is less restricted by market raw materials, and is basically not influenced by air temperature.

The invention discloses a geomembrane core wall hilly pond earth-rock dam and a construction method, wherein the geomembrane core wall hilly pond earth-rock dam is composed of a dam body, a geomembrane, residual soil, hilly soil and silty clay, the geomembrane is built in the middle of the dam body, the residual soil and the hilly soil are laid on the left and right sides of the geomembrane core wall earth-rock dam and are compacted in a layering mode, the thickness of the silty clay is more than 20cm and laid on the left and right sides of the geomembrane, and the geomembrane is protected from being punctured by the residual soil and the ridge angle of the hilly soil during construction and operation of the earth-rock dam.

In addition, the invention patent with the publication number of CN106522170A of the beam force application discloses a new dam type using a concrete impervious wall as a dam impervious body, and the scheme is that the concrete impervious core wall is connected with a dam foundation impervious curtain at the lower part to form an integral dam impervious system; the structural size t1 of the concrete impervious core wall and the structural size t2 of the transition layers on the upstream and downstream sides of the core wall are respectively equal to or more than (5-10) t1 when the height of the dam is less than 60-70 m, and t2 is more than 10 times of t1 when the height of the dam is more than 70m (namely, a high dam). The concrete implementation is that dam materials of each subarea are firstly constructed and filled, and finally, the impervious wall is made.

The technologies have the advantages, and some innovative schemes are provided for the impervious core wall technology of the earth-rock dam, the schemes mostly relate to core wall impervious bodies formed by clay or asphalt, however, the clay impervious bodies are large in using amount, and if a storage area and a dam site do not have a proper stock ground and are remotely transported, a large amount of resources such as cultivated land and forest land are occupied, and large economic and environmental costs are paid. For the asphalt concrete anti-seepage body, the base has high requirements on geological conditions, special asphalt concrete mixing facilities are needed, the construction period is long, and the investment is large. The geomembrane is easy to tear, so that the geomembrane is usually used in temporary engineering and has a narrow application range. And CN106522170A shortcoming is that the concrete core wall is easy to be out of shape and destroyed, needs the peripheral transition material that adds, and the cost is higher.

Therefore, the structural form and the construction technology of the existing earth-rock dam are not suitable for the requirements of the current social and economic development on the ecological environment and the engineering construction efficiency, and need to be further optimized and developed.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention aims to provide a construction method of a pouring type impervious core earth-rock dam and a novel pouring type impervious core earth-rock dam structure constructed according to the method.

The invention is realized by the following steps:

the invention relates to a construction method of a pouring type impervious core earth-rock dam, which is characterized in that the earth-rock dam is designed into an upper dam body, a lower dam body and an impervious system, and consists of three parts, namely an underwater dam body filling and dam foundation processing method, a forming method of a pouring type impervious core wall and a dam material selecting and controlling method; the underwater dam filling and dam foundation processing method is that dam materials are directly filled underwater, and the filling and dam foundation covering layer is subjected to vibroflotation encryption processing to form a lower dam body; the method for forming the pouring type impervious core wall comprises the steps of adopting pulse grouting to form the impervious core wall on a dam body and a dam foundation covering layer, adopting curtain grouting to form an impervious curtain to bedrock, and forming an impervious system of the earth-rock dam together; the dam material selection and control method is characterized in that the upper dam body filler is widely selected from sand gravel, soft rock, gravel soil, weathered materials and stone slag materials excavated by buildings in a reservoir area, and compaction control is performed by adopting a comprehensive method of test combined calculation analysis, filling indexes and construction parameters.

In the technical scheme of the invention, the novel earth and rockfill dam body structure consists of an upper dam body, a lower dam body and an anti-seepage system. And directly throwing filling dam materials under water to perform vibroflotation and encryption on the lower dam body. The upper dam body is formed by layering and rolling of reservoir gravel, soft rock, gravel soil, weathered materials and excavation slag materials, and compaction control is performed by adopting a comprehensive method of test combined calculation analysis, filling indexes and construction parameters. The seepage-proofing system is formed by connecting a basement rock curtain with a seepage-proofing core wall formed on a dam body and a covering layer by a pulsating grouting technology. The earth-rock dam is suitable for dam sites with the sum of the water depth of a riverbed and the thickness of a loose sand gravel covering layer smaller than 50 m.

The detailed technical scheme of the invention is as follows:

one of the key technologies of the invention is an underwater dam filling and dam foundation processing method. The construction method is characterized in that stones are directly dumped and filled at the foot of an upper and a lower upstream slopes to form a dike, sand gravel or stone slag materials with a certain gradation are dumped and filled in the middle of the upper and the lower dikes, and the dike is filled out of the water surface to a flood height to form the overwater construction platform. And (3) adopting vibroflotation (or other encryption measures) encryption on the dam body and the dam foundation which are thrown and filled on the platform, so that the dam body and the dam foundation can reach the required compactness, and underwater dam building is realized. The dike is preferably arranged outside the boundary between the dam slope extension line and the dam foundation of the earth-rock dam, can be used as a temporary construction channel to provide enclosure for underwater filling dam bodies, and forms a permanent pressing platform and a protective body for dam toe in the later period. The prop dam is preferably filled with stone with good quality. The width of the prop bank top is generally 6 m-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 reverse filter material, and the gradation meets the reverse filter requirement.

Preferably, the dike stone has a saturated compressive strength of not less than 30MPa, a softening coefficient of not less than 0.75 and a particle diameter of 200mm to 1000 mm.

As a preferable scheme, the horizontal thickness of the filter material is more than 5m, the saturated compressive strength is not less than 60MPa, and the softening coefficient is not less than 0.75.

Preferably, the maximum particle diameter D of the sand-gravel or stone-slag material which forms the lower dam body is thrown and filled in the water_max<200mm, and the content of organic matters and impurities is controlled within 5 percent. The saturated compressive strength of the stone slag material is not less than 30Mpa, and the softening coefficient is not less than 0.75.

As a preferred scheme, when the encryption mode adopts vibroflotation encryption, the piles are generally arranged according to an equilateral triangle with the distance (a) of 2-3 m, and sand gravel and stone slag materials which are thrown and filled underwater between dikes and loose dam foundation covering layers are treated. Before construction, a special field test is required to determine relevant construction parameters.

The second key technique of the invention is perfusionA method for forming an impervious core wall. Namely, the dam body and the dam foundation covering layer are subjected to pulse grouting to form an impervious core wall, and bedrock is subjected to curtain grouting to form an impervious curtain to jointly form an impervious system of the earth-rock dam. Further, the pouring type impervious core wall adopts a pulsating grouting technology, the middle of the dam body is provided with drilled holes, the rows are arranged into 2-5 rows according to the height of the dam, the effective thickness D of the formed impervious core wall is larger than H/15(H is the maximum water retaining head), and the permeability coefficient is smaller than 5 multiplied by 10^{- 6}cm/s and an elastic modulus of 200 to 1000 MPa.

As a preferred scheme, the pulsating grouting impervious core wall can be implemented by an upper stage project and a lower stage project, wherein the first stage project is a dam body and a dam foundation below the flood height, and the second stage project is a dam body above the flood height; when the conditions allow, the dam can be implemented at one time on the top of the dam after the dam body is finished.

Preferably, the grouting slurry is a clay cement paste slurry having a fluidity of 60mm to 120 mm. The slurry mixing proportion (mass ratio) can adopt cement: clay: additive: 100 parts of water, (50 to 200 parts of water), (2 to 5 parts of water), and (140 to 250 parts of water).

As a preferable scheme, the additive is formed by mixing one or more of sodium sulfate, sodium metaaluminate, sodium metasilicate, cellulose, vegetable gum and polyacrylamide, the cellulose and the sodium metaaluminate are preferably selected as main materials, and finally, the additive is determined by tests according to the properties of dam bodies and dam foundation rock soil.

Preferably, the clay slurry has a density of 1.2g/cm³～1.25g/cm³The specific gravity of the paste slurry is 1.5g/cm³～1.65g/cm³The initial setting time is 2-6 h.

As a preferred scheme, the grouting adopts a special plunger pump, the pumping frequency is 6-12 times per minute, and the pumping amount of a single cylinder per time is more than 5L.

Preferably, the pulsating grouting is performed in a bottom-up stage, each stage is 0.5 to 1.0m, and the slurry diffusion radius is 1.0 to 1.5 m.

As a preferable scheme, when the dam height is lower than 30m, the grouting holes can be arranged in 2 rows, the hole pitch is 1.0-1.5 m, and the row pitch is 0.8-1.0 m. The grouting is preferably carried out first in the upstream row and then in the downstream row. The first row grouting pressure is 0.6MPa to 3.5MPa, and the second row grouting pressure can be improved by about 10 to 30 percent. The effective thickness of the formed impervious core wall is more than 3.0 m.

As a preferable scheme, when the dam height is 25 m-60 m, the grouting holes can be arranged in 3 rows, the hole pitch is 1.0 m-2.0 m, and the row pitch is 0.8 m-1.2 m. The grouting is carried out in two rows of the upstream and the downstream, and finally the middle row. The upstream and downstream grouting pressure is 0.6 MPa-3.5 MPa; the pressure of the middle drainage and grouting can be improved by about 20-50%. The effective thickness of the formed impervious core wall is more than 4.5 m.

Preferably, when the dam is 55m to 90m high, the grouting holes can be arranged in 4 rows, and if necessary, 5 rows, with the hole pitch of 1.0m to 2.5m and the row pitch of 0.8m to 1.2 m. The grouting is carried out in two rows of the upstream and the downstream, and finally the middle row. The upstream and downstream grouting pressure is 0.6 MPa-3.5 MPa; the pressure of the middle drainage and grouting can be improved by about 30-50%. The effective thickness of the formed impervious core wall is more than 6 m.

The third key technology of the invention is a dam material selection and control method. When no seepage-proof earth materials exist in the engineering area of the earth-rock dam, the pouring type seepage-proof core wall is used as a seepage-proof body. The upper dam body filling material is widely selected from sand gravel, soft rock, gravel soil, weathered materials and stone slag materials excavated by buildings in a reservoir area, and compaction control is performed by adopting a comprehensive method of field test combined with calculation analysis, filling indexes and construction parameters, so that the filling standard requirement of the dam body is met. The problems of single filling control index, high dam material requirement, more abandoned materials and the like of the traditional earth-rock dam material are solved, and dam material selection is expanded.

As a preferable scheme, the permeability coefficient of the weathered material and the gravelly soil is not controlled, and the gravel content is controlled only and is generally between 40 and 60 percent.

As a preferable scheme, for the sand gravel material, the river bed material in the reservoir area can be widely selected, and the maximum grain diameter D_max<200mm, and the content of organic matters and impurities is controlled within 5 percent.

As a preferred scheme, soft rock excavation slag materials are selected according to the material properties of the soft rock excavation slag materials by referring to the standards of weathered materials and gravelly soilAnd selecting and filling different areas of the dam. Maximum particle size D of slag material for hard rock excavation_max<500mm。

Furthermore, for the rolling compaction filling standard, in the specific construction, the compaction control is carried out by combining a field test with a comprehensive method of calculation analysis, filling indexes and construction parameters instead of judging the compaction degree, the relative density or the porosity as a unique design control index.

Preferably, the spreading thickness of the weathered materials, the gravel soil and the sand-gravel is not more than 400mm, the spreading thickness of the hard rock excavating materials is not more than 800mm, and the maximum grain size of the dam materials is not more than 2/3 of the spreading thickness. The same dam material is adopted as much as possible for the same layer of paving and filling.

As a preferable scheme, due to the complexity of the dam material, the number of times of rolling the dam material is strictly controlled to be more than 10 times (2 times of static pressure and 8 times of vibration). The weight of the rolling machine is generally not less than 25 t.

As a preferred scheme, the water doping amount is generally 5-15% according to different dam materials.

Further, after the construction parameters are adopted for compaction, compaction control indexes (compactness, relative density or porosity) corresponding to weathered materials, gravel soil, sand gravel, hard rock excavation materials and the like are selected as comprehensive control standards for compaction.

The pouring type anti-seepage core earth-rock dam structure constructed by the method comprises an upstream dike and a downstream dike, wherein the inner sides of the upstream dike and the downstream dike are respectively provided with dike inner side reverse filters formed by casting and filling reverse filter materials, 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 formed by casting and filling sand gravel and stone slag materials and fills the water surface to a flood height; arranging vibroflotation packing piles in the underwater filling dam body and the dam foundation covering layer for packing; the middle part of the underwater throwing filling dam body is provided with a lower dam body impervious core wall, a dam foundation curtain is arranged below the lower dam body impervious core wall, an upper dam body impervious core wall is arranged above the lower dam body impervious core wall, and an upstream dam shell and a downstream dam shell are respectively arranged on the upstream side and the downstream side of the upper dam body impervious core wall; the slope surfaces of the upstream dam shell and the downstream dam shell are respectively provided with an upstream slope protection and a downstream drainage body.

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

(1) the invention is used as a novel earth and rockfill dam structure type, and the application range of the earth and rockfill dam is expanded.

(2) The invention is directly filled underwater, without need of cofferdam and foundation pit in traditional meaning, without digging out riverbed covering layer, the filling speed of dam body is fast, construction is simple, and flood safety is more guaranteed.

(3) The invention has wide dam material source, widely utilizes engineering to excavate the waste slag to fill the dam, reduces land acquisition of a waste slag field, and is beneficial to ecological environment protection and soil and water conservation.

(4) The invention adopts the pouring type impermeable core wall, the core wall structure belongs to the original technology in the field, the technology can avoid the acquisition and the damage of cultivated land and forest land caused by the large-scale exploitation of impermeable clay materials, and the environmental risk is reduced. The construction method solves the problem that the construction of the cohesive soil material can not be carried out in rainy days, is convenient to construct, and is favorable for coordinating the deformation of the dam and relatively improving the durability of an anti-seepage system as a flexible anti-seepage body.

(5) The invention can effectively shorten the total construction period and is beneficial to exerting the engineering benefit in advance.

(6) The invention can optimize the construction process of the earth-rock dam, save cofferdam filling, weir body seepage prevention, foundation pit excavation, foundation pit pumping, save stock ground, slag yard land acquisition and related water conservation and environmental protection measures, and obviously save the engineering investment.

Drawings

FIG. 1 is a schematic structural view of a dam body of a pouring type impervious core earth-rock dam of the invention;

FIG. 2 is a schematic view of underwater dumping of a lower dam;

FIG. 3 is a schematic view of a lower dam structure;

FIG. 4 is a schematic view of a pulsating grout impermeable core wall arrangement;

FIG. 5 is a schematic view of the lap joint of the impervious core walls of the upper and lower dam bodies;

description of reference numerals: 1-upstream dike, 2-downstream dike, 3-underwater cast-fill dam body, 4-vibroflotation compaction pile, 5-lower dam body impervious core wall, 6-dam foundation curtain, 7-upstream dam shell, 8-downstream dam shell, 9-upper dam body impervious core wall, 10-upstream slope protection, 11-downstream slope drainage, 12-bedrock covering layer, 13-bedrock, 14-grouting upstream row, 15-grouting downstream row, 16-grouting middle row, 17-core wall lap joint area and 18-dike inner side inverted filter.

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.

The invention is implemented as follows:

as shown in figure 1, the dam body structure comprises an upstream dike 1, a downstream dike 2, an underwater cast-fill dam body 3, a vibroflotation compaction pile 4, a lower dam body impervious core wall 5, a dam foundation curtain 6, an upstream dam shell 7, a downstream dam shell 8, an upper dam body impervious core wall 9, an upstream protection slope 10 and a downstream slope drainage slope 11.

As shown in FIG. 2, the invention is constructed according to the following steps:

firstly, an upstream dike 1 and a downstream dike 2 are constructed by throwing and filling on the bank side to enter an occupied river bed, and the top elevation of the dike is determined according to the rise of the flood water level. 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 18 with the horizontal width not less than 5 m. Then, sand, gravel and stone slag materials with certain grading requirements are continuously filled between the upstream and downstream reverse filtering bodies 18, and the materials are filled out of the water surface to the flood height to form the underwater filling dam body 3.

And thirdly, the underwater dumped and filled dam body 3 and the dam foundation covering layer 12 are encrypted by adopting the vibroflotation encryption piles 4 to ensure that the compactness of the dam body and the dam foundation required by design is achieved, and the gravity penetration is adopted for detection.

When the vibroflotation compaction pile is implemented, firstly, piles are distributed on a platform of the underwater throwing filling dam body 3, high-power hydraulic vibroflotation equipment is sequentially adopted to form holes to the designed depth, gravel or crushed stones are added into the holes, and vibroflotation compaction is carried out. The lifting height of the vibroflotation device is controlled to be 1.5-2.0 m each time, and the feeding amount of the encrypted pile body with 0.5m in the hole is ensured.

And if 2 and 3 are shown, constructing a lower impervious core wall 5 and a dam foundation curtain 6 after vibroflotation and compaction. The upper row 14 is constructed and grouted, the clay cement paste slurry with the fluidity of 60 mm-120 mm is poured, after the construction is finished, the lower row 15 is grouted, and finally the middle row 16 is grouted. The dam foundation curtain 6 is implemented next. Thereby forming a lower dam body and an anti-seepage body of the dam foundation.

As shown in figure 4, for the same-row grouting holes, the hole spacing A is generally arranged according to 1.0-2.5 m, the row spacing B of two rows of grouting upstream rows 14 and two rows of grouting downstream rows 15 is arranged according to the thickness of the impervious core wall meeting the design requirement, and the effective thickness D of the core wall is H/15(H is the maximum water retaining head).

The grouting adopts cement clay paste slurry, the slurry is prepared by mixing cement, clay, an additive and water according to the weight ratio of (50-200) to (2-5) to (140-250), the additive is one or a mixture of sodium sulfate, sodium metaaluminate, sodium metasilicate, cellulose, vegetable gum and polyacrylamide, the cellulose and the sodium metaaluminate are preferably used as main materials, and the cement clay paste slurry is determined by tests according to the properties of dam bodies and dam foundation rock soil.

The density of the prepared clay slurry is 1.2g/cm³～1.25g/cm³The density of the cement clay paste slurry is 1.5g/cm³～1.65g/cm³The initial setting time is 2-6 h.

As shown in figure 1, after the construction of the impervious core wall 5 and the dam foundation curtain 6 of the lower dam body is finished, an upstream dam shell 7 and a downstream dam shell 8 are filled, and the upstream dam body and the downstream dam body synchronously and uniformly rise. And after the dam body is filled to the top, implementing the upper dam body impervious core wall 9, wherein the concrete drilling and grouting construction mode is similar to that of the lower dam body impervious core wall 5.

As shown in figure 5, when the impervious core wall 9 of the upper dam is constructed, the bottom of the grouting hole extends into the impervious core wall 5 of the lower dam by 3-5 m to form a core wall lap joint area 17.

The upstream dam shell 7 and the downstream dam shell 8 can be widely made of gravel, soft rock, gravel soil and weathered materials in the reservoir area, and the stone slag excavated by the building is fully utilized. For the dam filling material, the requirements of dam body filling standards are met by combining field tests with comprehensive control technologies of calculation analysis, filling indexes and construction parameters.

When weathered materials, gravel soil and sand gravel are adopted, the paving and filling thickness is not more than 400 mm. When the hard rock excavating material is adopted, the paving and filling thickness is not more than 800 mm. The maximum particle size of the dam is not greater than 2/3 of the fill thickness.

The number of times of rolling the dam material is strictly controlled to be more than 10 times (static pressure is 2 times, and vibration is 8 times). The weight of the rolling machine is generally not less than 25 t.

The water doping amount is generally 5-15% according to the difference of dam materials during construction.

After the rolling construction of each layer is finished, on-site compaction quality detection is required, and compaction control indexes (compactness, relative density or porosity) corresponding to weathered materials, soft rock, gravelly soil, sand gravel and hard rock excavation materials are selected for detection respectively. And after the detection result meets the compaction standard, starting the rolling construction of the next layer.

After the above steps are completed, the construction of the upstream slope protection 10 and the downstream drainage body 11 is started, and the construction method is a conventional method and will not be 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.