CN111197300A - Earth-rock cofferdam back slope type seepage-proofing dam and reverse construction method - Google Patents
Earth-rock cofferdam back slope type seepage-proofing dam and reverse construction method Download PDFInfo
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- CN111197300A CN111197300A CN202010023244.7A CN202010023244A CN111197300A CN 111197300 A CN111197300 A CN 111197300A CN 202010023244 A CN202010023244 A CN 202010023244A CN 111197300 A CN111197300 A CN 111197300A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B7/00—Barrages or weirs; Layout, construction, methods of, or devices for, making same
- E02B7/02—Fixed barrages
- E02B7/04—Dams across valleys
- E02B7/06—Earth-fill dams; Rock-fill dams
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02B—HYDRAULIC ENGINEERING
- E02B3/00—Engineering works in connection with control or use of streams, rivers, coasts, or other marine sites; Sealings or joints for engineering works in general
- E02B3/16—Sealings or joints
Abstract
The invention belongs to the technical field of hydraulic and hydroelectric engineering construction, and relates to an earth-rock cofferdam back slope type seepage-proofing dam and a reverse construction method, wherein the seepage-proofing dam comprises: the cofferdam comprises a middle stone stacking layer of the cofferdam, a wide step stone stacking layer of the cofferdam, an upstream air-tight clay material layer, an upper bagged coarse sand transition material layer, an upper back slope clay anti-seepage layer, a lower bagged coarse sand transition material layer, a lower back slope clay anti-seepage layer and a boulder presser foot layer. By combining with the corresponding construction method, the invention effectively prevents seepage, simplifies the construction steps and reduces the manufacturing cost by the reverse construction method of constructing the clay impermeable layer of the upper back slope firstly and then constructing the clay impermeable layer of the lower back slope.
Description
Technical Field
The invention belongs to the technical field of hydraulic and hydroelectric engineering construction, and particularly relates to an earth-rock cofferdam back slope type seepage-proofing dam and a reverse construction method.
Background
In the hydraulic and hydroelectric engineering at present, when an earth-rock cofferdam is adopted, the cofferdam mainly has the following seepage-proofing mode: the clay inclined wall (or combined with the laying cover) of the upstream slope surface is used for seepage prevention, the clay core wall is used for seepage prevention, the waterproof geomembrane is used for seepage prevention at the axial line part of the cofferdam, the concrete seepage-proof wall or the high-pressure jet seepage-proof wall is used for treating the underwater part of the clay core wall or the waterproof geomembrane seepage-proof cofferdam, the seepage prevention of the clay inclined wall has the problems of high difficulty in implementing in water (particularly the laying cover part) and poor guarantee performance of seepage prevention effect, and the seepage prevention mode that the clay core wall is combined with the lower seepage-proof wall or the seepage-proof geotextile is combined with the lower seepage-.
For example, the Chinese patent application number is: the patent of CN201720964122.1 discloses a concrete cut-off wall heightening and seepage-proofing structure, which comprises an original earth-rock cofferdam and an original seepage-proofing wall arranged inside the original earth-rock cofferdam, wherein the outer side of the original earth-rock cofferdam is provided with a retaining wall, the upper part of the original earth-rock cofferdam is provided with a heightening earth-rock cofferdam, and the upper part of the original seepage-proofing wall is provided with a heightening cut-off wall; and the top of the heightened earth-rock cofferdam corresponding to the upstream side of the original earth-rock cofferdam is drilled downwards along the axis direction for pouring high-pressure jet grouting, and fine-rock concrete is arranged at the lower part of the high-pressure jet grouting body. The beneficial effects of the utility model are that increase the cut-off wall and can adopt the height to spout the cut-off wall, at former continuous drilling or cutting grooving in the top of the wall that prevents leaking, new and old concrete gomphosis is connected to hang at new and old concrete interface and put the stagnant water board, can solve new and old concrete connection density nature poor, waterproof poor scheduling problem. But the structure is more complicated, and the construction step is loaded down with trivial details, and the cost is higher.
Disclosure of Invention
The invention aims to provide an earth-rock cofferdam back slope type seepage-proofing dam and a reverse construction method aiming at the defects of the prior art, so that the seepage-proofing effect is improved, and the construction period is shortened.
The technical scheme for solving the problems is as follows:
an earth-rock cofferdam back slope type seepage control dam, comprising: the cofferdam comprises a middle stone stacking layer of the cofferdam, a wide-step stone stacking layer of the cofferdam, an upstream air-blocking clay material layer, an upper bagged coarse sand transition material layer, an upper back slope clay anti-seepage layer, a lower bagged coarse sand transition material layer, a lower back slope clay anti-seepage layer and a boulder presser foot layer; an upstream air-tight clay material layer is arranged at the upstream of the middle rockfill layer of the cofferdam, a wide-step rockfill layer of the cofferdam is arranged at the bottom of the downstream of the middle rockfill layer of the cofferdam, a lower bagged coarse sand transition material layer is arranged at the downstream of the wide-step rockfill layer of the cofferdam, an upper bagged coarse sand transition material layer is arranged at the upper part of the downstream of the middle rockfill layer of the cofferdam and the top of the wide-step rockfill layer of the cofferdam, an upper back slope clay anti-seepage layer is arranged at the upper part of the upper bagged coarse sand transition material layer, a lower back slope clay anti-seepage layer is arranged at the downstream of the upper back slope, the wide-step cofferdam rock piling layer is arranged in an area formed by enclosing the middle rock piling layer, the upper bagged coarse sand transition material layer and the lower bagged coarse sand transition material layer of the cofferdam.
Furthermore, blasting excavation stone slag materials are adopted in the rock-fill layer in the middle of the cofferdam, the grain size is less than or equal to 700mm, and continuous grading is adopted; blasting excavation stone slag materials or natural sand granules with the particle size of less than or equal to 300mm are adopted within a range which is 3m away from the upstream side slope, continuous grading is carried out, the content of the particles with the particle size of less than 5mm is 5% -20%, and the content of the particles with the particle size of less than 0.1mm is less than 3%; the middle piling stone layer of the cofferdam adopts block stones or steel reinforcement cage stones with the grain diameter of more than 1000mm at a closure section of 10-30 m.
Furthermore, the rock-fill layer of the wide step of the cofferdam adopts blasting excavation stone slag materials, the grain diameter is less than or equal to 700mm, and the rock-fill layer is graded continuously.
Furthermore, the upstream gas-closing clay material layer adopts powder clay material or clay material, the content of the powder clay is more than 10%, the plasticity index is 10-17, the content of the clay material is more than 30%, and the plasticity index is more than 17.
Furthermore, the thicknesses of the upper bagged coarse sand transition material layer and the lower bagged coarse sand transition material layer in the horizontal direction are 1.5-2.0m, coarse sand materials are adopted, the average particle size is more than 0.5mm, and the fineness modulus is 3.1-3.7.
Furthermore, the upper back slope clay impermeable layer and the lower back slope clay impermeable layer are both clay materials, the clay content is more than 30%, the plasticity index is more than 17, the trapezoid cross section has a slope of 1/1.75-1/2 on the side facing the sky.
Furthermore, the boulder presser foot layer adopts boulders with the grain diameter of 0.5-1.0m, the thickness is 2-3m, the trapezoid cross section has the slope of 1/1.5-1/1.75 of the side close to the hollow.
The invention also provides a reverse construction method of the earth-rock cofferdam back slope type seepage-proofing dam, which comprises the following specific steps:
step 1, construction preparation:
setting the size of a cofferdam, carrying out on-site measurement and paying-off, monitoring hydrological weather in an intercepting period, preparing intercepting materials and preparing intercepting machinery;
cutting off a river by a vertical plugging method to form a middle piling layer of a cofferdam, and carrying out blasting excavation stone slag material filling with the maximum particle size of 0.7m by a dump truck in a mode of advancing occupation from one bank of a river channel to the opposite bank or from both banks to the middle of the river, wherein the slag material or natural sand gravel material with the particle size of below 0.3m is filled in the range of 3m at the upstream of the middle piling layer of the cofferdam, a bulldozer is used for paving occupation, a back shovel is used for assisting in spreading, and large stones or steel reinforcement cages with the particle size of above 1.0m are filled in a 10-30m longmen section for folding;
step 3, filling a wide step rock-fill layer of the cofferdam:
the wide-step rock-fill layer of the cofferdam is constructed synchronously with the rock-fill layer in the middle of the cofferdam during closure, the filling is filled from one bank to the other bank or from both banks to the middle of the river channel, the material is transported by a dump truck, a bulldozer paves and rolls, and the material is paved by a back shovel in an auxiliary way; blasting excavation stone slag material with the maximum grain size of 0.7m is adopted for filling, and continuous grading is carried out;
step 4, filling an upstream gas-tight clay material layer:
clay materials are dumped and filled at the upstream of the cofferdam for preliminary seepage prevention, so that the seepage amount is reduced; adopting a dump truck to transport the air-tight clay material, pouring the clay material on the top of a cofferdam dike after closure, and throwing the clay material to an upstream slope at the top of the cofferdam by a long-arm backhoe;
draining the foundation pit in the range of the upstream cofferdam and the downstream cofferdam, and reducing the water level to be 0.5-1.0m below the top surface of the wide step piled stone layer of the cofferdam;
step 6, filling an upper bagged coarse sand transition material layer and an upper back slope clay impermeable layer:
filling the bottom of the side of the cofferdam back slope of the upper bagged coarse sand transition material layer, and then performing face construction from bottom to top; meanwhile, constructing an upper back slope clay impermeable layer, and keeping the upper bagged coarse sand transition material layer higher than the upper back slope clay impermeable layer by 0.3-1.0m in the paving process;
step 7, draining water at the lower part of the foundation pit, and constructing a coarse sand transition material layer bagged at the lower part of the cofferdam back slope side and a lower back slope clay impermeable layer:
a centrifugal pump is arranged in the foundation pit for draining water until the positions of a coarse sand transition material layer bagged on the lower part of the back slope side of the cofferdam and a clay impermeable layer on the lower back slope leak out of the foundation pit foundation surface;
the construction step of the bagged coarse sand transition material layer at the lower part comprises the steps of conveying the bagged coarse sand material to the site by a dump truck, filling the coarse sand into a hemp rope tying opening for weaving bags, layering and stacking by adopting a tiling method from bottom to top, and carrying out up-and-down staggered joint; filling a lower back slope clay anti-seepage layer while stacking the lower bagged coarse sand transition material layer, wherein the lower bagged coarse sand transition material layer is 0.3-1.0m higher than the lower back slope clay anti-seepage layer in the laying process;
filling the bottom of the clay impermeable layer on the back slope at the lower part, paving the low-lying water part above the water surface by adopting bagged soil yards, and then filling mechanically; when the clay impermeable layer on the lower back slope is mechanically filled, the filling is carried out from bottom to top in a layering way, a dump truck transports soil materials, a bulldozer levels the soil materials, the thickness of the layering is 0.25-0.35m, and the soil materials are vibrated, rolled and compacted;
the large stones with the particle size of 0.5-1.5m are adopted for layered paving, a dump truck is adopted for transporting the large stones, the large stones are poured to an operation surface, a backhoe is used for leveling and paving, and the regular large stones are adopted on one side close to the foundation pit.
Further, in step 4, when the long-arm backhoe for throwing and filling clay materials cannot cover the whole clay throwing and filling range, the barge is used for conveying the materials for filling outside the operation range of the long-arm backhoe, and a grab bucket or a backhoe is matched on the barge to throw and fill the filling to a specified position.
Further, in the step 4, the clay material is a powdered clay material or a clay material, wherein the powdered clay material requires that the clay content is more than 10%, the plasticity index is 10-17, the clay material requires that the clay content is more than 30%, and the plasticity index is more than 17.
Further, in step 6, the construction steps of the upper bagged coarse sand transition material layer are as follows: conveying the coarse sand for bagging to a construction site by using a dump truck, filling the coarse sand into a hemp rope binding opening for weaving bags, layering and stacking by adopting a flat laying method from bottom to top, and performing staggered joint on an upper layer and a lower layer; the average grain diameter of the coarse sand is more than 0.5mm, and the fineness modulus is 3.1-3.7;
the construction step of the clay anti-seepage layer of the upper back slope comprises the steps of conveying clay materials to an operation surface by using a dump truck, and paving and leveling by using a bulldozer, wherein the thickness of a paving layer is 0.25-0.35 m; the clay material has a clay content of more than 30% and a plasticity index of more than 17.
The invention has the beneficial effects that:
the earth-rock cofferdam back slope type seepage-proofing dam and the reverse construction method thereof are mainly characterized in that the seepage-proofing body is arranged on one side of the cofferdam back slope and is divided into an upper part and a lower part, so that seepage-proofing body filling construction is realized under the anhydrous condition; firstly, constructing an upper back slope clay impermeable layer, then constructing a lower back slope clay impermeable layer, only constructing the upper back slope clay impermeable layer in the first stage, wherein the water seepage of the cofferdam is only in the upper range and is inhibited by an upstream gas-tight clay material layer, and the water seepage amount is effectively controlled, thereby being beneficial to the construction in the stage; and in the second stage, the lower back slope clay impermeable layer is constructed, the upper back slope clay impermeable layer and the air-tight clay bed soil in the front upstream of the cofferdam jointly play a role, so that the water seepage amount of a foundation pit is controlled to a certain extent when the lower back slope clay impermeable layer is constructed, and the back slope type impermeable dam of the earth-rock cofferdam and the reverse construction method thereof have the beneficial effects of high construction speed, good defense effect and simplicity and convenience in construction.
Drawings
FIG. 1 is a schematic structural view of a back slope type seepage-proofing structure of the earth-rock cofferdam of the invention;
in the figure: 1-cofferdam middle rock stacking layer, 2-cofferdam wide step rock stacking layer, 3-upstream air-blocking clay material layer, 4-upper bagged coarse sand transition material layer, 5-upper back slope clay anti-seepage layer, 6-lower bagged coarse sand transition material layer, 7-lower back slope clay anti-seepage layer and 8-boulder presser foot layer.
Detailed Description
In order that the above objects, features and advantages of the present invention can be more clearly understood, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments, it being understood that the embodiments and features of the embodiments of the present application can be combined with each other without conflict.
As shown in fig. 1, an earth-rock cofferdam back slope type seepage control dam comprises: the cofferdam comprises a cofferdam middle stone stacking layer 1, a cofferdam wide step stone stacking layer 2, an upstream air-blocking clay material layer 3, an upper bagged coarse sand transition material layer 4, an upper back slope clay anti-seepage layer 5, a lower bagged coarse sand transition material layer 6, a lower back slope clay anti-seepage layer 7 and a boulder presser foot layer 8; an upstream air-tight clay material layer 3 is arranged at the upstream of a middle piling layer 1 of the cofferdam, a wide step piling layer 2 of the cofferdam is arranged at the bottom of the downstream of the middle piling layer 1 of the cofferdam, a lower bagged coarse sand transition material layer 6 is arranged at the downstream of the wide step piling layer 2 of the cofferdam, an upper bagged coarse sand transition material layer 4 is arranged at the upper part of the middle piling layer 1 of the cofferdam and the top of the wide step piling layer 2 of the cofferdam, an upper back slope clay anti-seepage layer 5 is arranged at the upper part of the upper bagged coarse sand transition material layer 4, a lower back slope clay anti-seepage layer 7 is arranged at the lower parts of the upper back slope clay anti-seepage layer 5 and the lower bagged coarse sand transition material, the upper bagged coarse sand transition material layer 4 is connected to the lower bagged coarse sand transition material layer 6, and the cofferdam wide step stone stacking layer 2 is arranged in an area formed by enclosing the middle stone stacking layer 1, the upper bagged coarse sand transition material layer 4 and the lower bagged coarse sand transition material layer 6 of the cofferdam.
In this embodiment, an upstream air-tight clay material layer 3, a cofferdam middle rock-piling layer 1, a cofferdam wide step rock-piling layer 2, an upper bagged coarse sand transition material layer 4, a lower bagged coarse sand transition material layer 6, an upper back slope clay anti-seepage layer 5, a lower back slope clay anti-seepage layer 7 and a boulder presser foot layer 8 are sequentially built from upstream to downstream of the earth-rock cofferdam back slope type anti-seepage dam.
In the embodiment, the rock piling layer 1 in the middle of the cofferdam adopts blasting excavation stone slag materials, the grain diameter is less than or equal to 700mm, and the rock piling layer is continuously graded; blasting excavation stone slag materials or natural sand granules with the particle size of less than or equal to 300mm are adopted within a range which is 3m away from the upstream side slope, continuous grading is carried out, the content of the particles with the particle size of less than 5mm is 5% -20%, and the content of the particles with the particle size of less than 0.1mm is less than 3%; the middle part of the cofferdam piling stone layer 1 adopts block stones or steel reinforcement cage stones with the grain diameter of more than 1000mm at a closure section of 10-30 m.
In the embodiment, the cofferdam wide step rock pile layer 2 adopts blasting excavation stone slag materials, the grain diameter is less than or equal to 700mm, and the grading is continuous.
In the embodiment, the upstream gas-closing clay layer 3 adopts powder clay or clay material, the content of the powder clay is more than 10 percent, the plasticity index is 10-17, the content of the clay material is more than 30 percent, and the plasticity index is more than 17.
In this embodiment, the upper bagged coarse sand transition material layer 4 and the lower bagged coarse sand transition material layer 6 have a horizontal thickness of 1.5-2.0m, are both coarse sand materials, have an average particle size of 0.5mm or more, and have a fineness modulus of 3.1-3.7.
In the embodiment, the upper back slope clay impermeable layer 5 and the lower back slope clay impermeable layer 7 are both clay materials, the clay content is more than 30%, the plasticity index is more than 17, the trapezoid cross section has a slope of 1/1.75-1/2 on the side facing the sky.
In the embodiment, the boulder presser foot layer 8 adopts boulders with the grain diameter of 0.5-1.0m, the thickness is 2-3m, the section of the trapezoid is 1/1.5-1/1.75 of the slope of the side close to the hollow.
A reverse construction method of an earth-rock cofferdam back slope type seepage-proofing dam comprises the following specific steps:
step 1, construction preparation:
setting the size of a cofferdam, carrying out on-site measurement and paying-off, monitoring hydrological weather in an intercepting period, preparing intercepting materials and preparing intercepting machinery;
the top width of the rock stacking layer 1 in the middle of the cofferdam is 4-6m, the slope ratio of an upstream side slope is 1/1.75-1/2, and the slope ratio of a downstream side slope is 1/1.5-1/1.75; the upper back slope clay impermeable layer 5 and the lower back slope clay impermeable layer 7 adopt trapezoidal sections; the upper bagged coarse sand transition material layer 4 and the lower bagged coarse sand transition material layer 6 play a role in drainage transition, and the thickness is 1.5-2.0 m; the top surface of the upstream air-tight clay material layer 3 is higher than the designed water level of 0.5-1.0m when intercepting, the top width is 2.0m, and the upstream gradient is 1/2-1/3;
cutting off a river by a vertical plugging method to form a rock piling layer 1 in the middle of a cofferdam, and transporting blasting excavation stone slag materials with the maximum particle size of 0.7m to fill by a dump truck in a mode of advancing occupation from one bank of a river channel to the opposite bank or from both banks to the middle of the river, wherein the slag materials or natural sand gravel materials with the particle size of less than 0.3m are filled in the range of 3m upstream of the rock piling layer 1 in the middle of the cofferdam, a bulldozer paves the occupation, and a back shovel is adopted to assist a spreading material to fill large stones or steel reinforcement gabions with the particle size of more than 1.0m in a 10-30m closure section;
step 3, filling a cofferdam wide step rock pile layer 2:
the cofferdam wide step rock-fill layer 2 is synchronously constructed along with the rock-fill layer 1 in the middle of the cofferdam during closure, filling from one bank to the other bank or from both banks to the middle of the river channel, carrying materials by a dump truck, spreading and rolling by a bulldozer, and spreading materials by a back shovel; blasting excavation stone slag material with the maximum grain size of 0.7m is adopted for filling, and continuous grading is carried out;
step 4, filling an upstream gas-tight clay material layer 3:
clay materials are dumped and filled at the upstream of the cofferdam for preliminary seepage prevention, so that the seepage amount is reduced; adopting a dump truck to transport the air-tight clay material, pouring the clay material on the top of a cofferdam dike after closure, and throwing the clay material to an upstream slope at the top of the cofferdam by a long-arm backhoe; when the long-arm back shovel filled with clay materials can not cover the whole clay throwing and filling range, carrying the filled soil outside the operation range of the long-arm back shovel by a barge, and throwing and filling the filled soil to a specified position by a grab bucket or a back shovel on the barge;
in this embodiment, the clay material is a powdered clay material or a clay material, the powdered clay material requires a clay content of more than 10% and a plasticity index of 10-17, the clay material requires a clay content of more than 30% and a plasticity index of more than 17;
draining the foundation pit in the range of the upstream cofferdam and the downstream cofferdam, and reducing the water level to be 0.5-1.0m below the top surface of the wide step piled stone layer 2 of the cofferdam;
step 6, filling an upper bagged coarse sand transition material layer 4 and an upper back slope clay impermeable layer 5:
filling the bottom of the side of the cofferdam back slope of the upper bagged coarse sand transition material layer 4, and then performing face construction from bottom to top; meanwhile, constructing an upper back slope clay impermeable layer 5, and keeping the upper bagged coarse sand transition material layer 4 higher than the upper back slope clay impermeable layer 5 by 0.3-1.0m in the paving process;
the construction steps of the upper bagged coarse sand transition material layer 4 are as follows: conveying the coarse sand for bagging to a construction site by using a dump truck, filling the coarse sand into a hemp rope binding opening for weaving bags, layering and stacking by adopting a flat laying method from bottom to top, and performing staggered joint on an upper layer and a lower layer; the average grain diameter of the coarse sand is more than 0.5mm, and the fineness modulus is 3.1-3.7;
the construction step of the clay impermeable layer 5 on the upper back slope is that a dump truck is adopted to convey clay to the working surface, a bulldozer is used for paving and leveling, and the thickness of the paving layer is 0.25-0.35 m; the clay content of the clay material is more than 30%, and the plasticity index is more than 17;
step 7, draining water at the lower part of the foundation pit, and constructing a coarse sand transition material layer 6 bagged at the lower part of the cofferdam back slope side and a lower back slope clay impermeable layer 7:
a centrifugal pump is arranged in the foundation pit for draining water until the water leaks out of the foundation pit foundation surface at the positions of a coarse sand transition material layer 6 bagged at the lower part of the cofferdam back slope side and a clay impermeable layer 7 at the lower part of the cofferdam back slope side;
a plurality of centrifugal pumps are arranged in the foundation pit for drainage, and gradually move downwards and downwards from the centrifugal pumps to lower positions in the foundation pit in batches along with the descending of the water level in the foundation pit, a water collecting well is arranged when the centrifugal pumps reach the bottommost part, the pumps are arranged in the water collecting well for drainage outwards, and the drainage is combined with a small submersible pump until the positions of a bag-packed coarse sand transition material 6 at the lower part of the back slope side of the cofferdam and a clay impermeable layer 7 at the lower part of the back slope side of the cofferdam are leaked out of the foundation pit construction base surface;
the construction step of the lower bagged coarse sand transition material layer 6 is that a dump truck is used for transporting the bagged coarse sand material to the site, the coarse sand is filled into a hemp rope binding opening for weaving bags, the woven bags are layered and stacked by adopting a flat laying method from bottom to top, and the upper part and the lower part are staggered; filling a lower back slope clay impermeable layer 7 while stacking the lower bagged coarse sand transition material layer 6, wherein the lower bagged coarse sand transition material layer 6 is 0.3-1.0m higher than the lower back slope clay impermeable layer 7 in the paving process until the lower bagged coarse sand transition material layer 6 is abutted with the upper bagged coarse sand transition material layer 4, and the lower back slope clay impermeable layer 7 is constructed to be higher than the top of the lower bagged coarse sand transition material layer 6 and abutted with the upper back slope clay impermeable layer 5;
filling the bottom of the clay impermeable layer 7 on the lower back slope, paving the low-lying water positions above the water surface by adopting bagged soil yards, and then filling mechanically; when the clay impermeable layer 7 on the lower back slope is mechanically filled, the filling is carried out from bottom to top in a layered mode, a dump truck transports soil materials, a bulldozer levels the soil materials, the thickness of a layered layer is 0.25-0.35m, and the soil materials are vibrated, rolled and compacted;
the large stones with the particle size of 0.5-1.5m are adopted for layered paving, a dump truck is adopted for transporting the large stones, the large stones are poured to an operation surface, a backhoe is used for leveling and paving, and the regular large stones are adopted on one side close to the foundation pit. The construction of the massive stone presser foot layer 8 is carried out, and the purpose is to improve the anti-sliding stability of the cofferdam body.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Claims (10)
1. The utility model provides an earth-rock cofferdam back of body slope formula prevention of seepage dam which characterized in that includes: the cofferdam comprises a middle stone stacking layer of the cofferdam, a wide-step stone stacking layer of the cofferdam, an upstream air-blocking clay material layer, an upper bagged coarse sand transition material layer, an upper back slope clay anti-seepage layer, a lower bagged coarse sand transition material layer, a lower back slope clay anti-seepage layer and a boulder presser foot layer; an upstream air-tight clay material layer is arranged at the upstream of the middle rockfill layer of the cofferdam, a wide-step rockfill layer of the cofferdam is arranged at the bottom of the downstream of the middle rockfill layer of the cofferdam, a lower bagged coarse sand transition material layer is arranged at the downstream of the wide-step rockfill layer of the cofferdam, an upper bagged coarse sand transition material layer is arranged at the upper part of the downstream of the middle rockfill layer of the cofferdam and the top of the wide-step rockfill layer of the cofferdam, an upper back slope clay anti-seepage layer is arranged at the upper part of the upper bagged coarse sand transition material layer, a lower back slope clay anti-seepage layer is arranged at the downstream of the upper back slope, the wide-step cofferdam rock piling layer is arranged in an area formed by enclosing the middle rock piling layer, the upper bagged coarse sand transition material layer and the lower bagged coarse sand transition material layer of the cofferdam.
2. The earth-rock cofferdam back slope type seepage control dam of claim 1, characterized in that the rock-fill layer in the middle of the cofferdam adopts blasting excavation stone slag material, the grain size is less than or equal to 700mm, and the continuous gradation is adopted; blasting excavation stone slag materials or natural sand granules with the particle size of less than or equal to 300mm are adopted within a range which is 3m away from the upstream side slope, continuous grading is carried out, the content of the particles with the particle size of less than 5mm is 5% -20%, and the content of the particles with the particle size of less than 0.1mm is less than 3%; the middle piling stone layer of the cofferdam adopts block stones or steel reinforcement cage stones with the grain diameter of more than 1000mm at a closure section of 10-30 m.
3. The earth-rock cofferdam back slope type seepage control dam of claim 1, characterized in that the cofferdam wide step mound layer adopts blasting excavation stone slag material, the grain size is less than or equal to 700mm, and the grading is continuous.
4. The earth-rock cofferdam back-slope type seepage control dam of claim 1, characterized in that the upstream air-blocking clay layer is made of powdery clay material or clay material, the content of powdery clay is more than 10%, the plasticity index is 10-17, the content of clay material is more than 30%, and the plasticity index is more than 17.
5. The earth-rock cofferdam back slope type seepage control dam of claim 1, characterized in that the thickness of the upper bagged coarse sand transition material layer and the lower bagged coarse sand transition material layer in the horizontal direction is 1.5-2.0m, the coarse sand materials are adopted, the average grain diameter is more than 0.5mm, and the fineness modulus is 3.1-3.7.
6. The earth-rock cofferdam back slope type seepage control dam of claim 1, characterized in that the upper back slope clay seepage control layer and the lower back slope clay seepage control layer are clay materials, the clay content is more than 30%, the plasticity index is more than 17, the trapezoid section, and the slope of the side facing the sky is 1/1.75-1/2.
7. The earth-rock cofferdam back slope type seepage control dam of claim 1, characterized in that the big stone presser foot layer adopts big stones with the grain size of 0.5-1.0m, the thickness is 2-3m, the trapezoid cross section and the slope of the side facing the sky is 1/1.5-1/1.75.
8. The reverse construction method of the earth-rock cofferdam back slope type seepage control dam of claim 1 is characterized by comprising the following specific steps:
step 1, construction preparation:
setting the size of a cofferdam, carrying out on-site measurement and paying-off, monitoring hydrological weather in an intercepting period, preparing intercepting materials and preparing intercepting machinery;
step 2, closure construction:
cutting off a river by a vertical plugging method to form a middle piling layer of a cofferdam, and carrying out blasting excavation stone slag material filling with the maximum particle size of 0.7m by a dump truck in a mode of advancing occupation from one bank of a river channel to the opposite bank or from both banks to the middle of the river, wherein the slag material or natural sand gravel material with the particle size of below 0.3m is filled in the range of 3m at the upstream of the middle piling layer of the cofferdam, a bulldozer is used for paving occupation, a back shovel is used for assisting in spreading, and large stones or steel reinforcement cages with the particle size of above 1.0m are filled in a 10-30m longmen section for folding;
step 3, filling a wide step rock-fill layer of the cofferdam:
the wide-step rock-fill layer of the cofferdam is constructed synchronously with the rock-fill layer in the middle of the cofferdam during closure, the filling is filled from one bank to the other bank or from both banks to the middle of the river channel, the material is transported by a dump truck, a bulldozer paves and rolls, and the material is paved by a back shovel in an auxiliary way; blasting excavation stone slag material with the maximum grain size of 0.7m is adopted for filling, and continuous grading is carried out;
step 4, filling an upstream gas-tight clay material layer:
clay materials are dumped and filled at the upstream of the cofferdam for preliminary seepage prevention, so that the seepage amount is reduced; adopting a dump truck to transport the air-tight clay material, pouring the clay material on the top of a cofferdam dike after closure, and throwing the clay material to an upstream slope at the top of the cofferdam by a long-arm backhoe;
step 5, draining:
draining the foundation pit in the range of the upstream cofferdam and the downstream cofferdam, and reducing the water level to be 0.5-1.0m below the top surface of the wide step piled stone layer of the cofferdam;
step 6, filling an upper bagged coarse sand transition material layer and an upper back slope clay impermeable layer:
filling the bottom of the side of the cofferdam back slope of the upper bagged coarse sand transition material layer, and then performing face construction from bottom to top; meanwhile, constructing an upper back slope clay impermeable layer, and keeping the upper bagged coarse sand transition material layer higher than the upper back slope clay impermeable layer by 0.3-1.0m in the paving process;
step 7, draining water at the lower part of the foundation pit, and constructing a coarse sand transition material layer bagged at the lower part of the cofferdam back slope side and a lower back slope clay impermeable layer:
a centrifugal pump is arranged in the foundation pit for draining water until the positions of a coarse sand transition material layer bagged on the lower part of the back slope side of the cofferdam and a clay impermeable layer on the lower back slope leak out of the foundation pit foundation surface;
the construction step of the bagged coarse sand transition material layer at the lower part comprises the steps of conveying the bagged coarse sand material to the site by a dump truck, filling the coarse sand into a hemp rope tying opening for weaving bags, layering and stacking by adopting a tiling method from bottom to top, and carrying out up-and-down staggered joint; filling a lower back slope clay anti-seepage layer while stacking and paving a lower bagged coarse sand transition material layer, wherein the lower bagged coarse sand transition material layer is 0.3-1.0m higher than the lower back slope clay anti-seepage layer in the paving process;
filling the bottom of the clay impermeable layer on the back slope at the lower part, paving the low-lying water part above the water surface by adopting bagged soil yards, and then filling mechanically; when the clay impermeable layer on the lower back slope is mechanically filled, the filling is carried out from bottom to top in a layering way, a dump truck transports soil materials, a bulldozer levels the soil materials, the thickness of the layering is 0.25-0.35m, and the soil materials are vibrated, rolled and compacted;
step 8, paving a boulder presser foot layer:
the large stones with the particle size of 0.5-1.5m are adopted for layered paving, a dump truck is adopted for transporting the large stones, the large stones are poured to an operation surface, a backhoe is used for leveling and paving, and the regular large stones are adopted on one side close to the foundation pit.
9. The reverse construction method of the earth-rock cofferdam back slope type seepage control dam of claim 8, characterized in that, in the step 4, when the long-arm backhoe for throwing filling clay materials can not cover the whole clay throwing filling range, the barge is used for transporting the filling earth outside the long-arm backhoe operation range, and the grab bucket or the backhoe is matched on the ship for throwing filling to the designated position; the clay material is a powder clay material or a clay material, wherein the content of clay grains is required to be more than 10 percent, the plasticity index is 10-17, the content of clay grains is required to be more than 30 percent, and the plasticity index is more than 17.
10. The reverse construction method of the earth-rock cofferdam back slope type seepage control dam of claim 8, wherein in the step 6, the construction step of the upper bagged coarse sand transition material layer is as follows: conveying the coarse sand for bagging to a construction site by using a dump truck, filling the coarse sand into a hemp rope binding opening for weaving bags, layering and stacking by adopting a flat laying method from bottom to top, and performing staggered joint on an upper layer and a lower layer; the average grain diameter of the coarse sand is more than 0.5mm, and the fineness modulus is 3.1-3.7;
the construction step of the clay anti-seepage layer of the upper back slope comprises the steps of conveying clay materials to an operation surface by using a dump truck, and paving and leveling by using a bulldozer, wherein the thickness of a paving layer is 0.25-0.35 m; the clay material has a clay content of more than 30% and a plasticity index of more than 17.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114960707A (en) * | 2022-05-24 | 2022-08-30 | 浙江华东工程建设管理有限公司 | Inclined wall geomembrane earth rock cofferdam structure suitable for higher manger plate flood peak of geomembrane |
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| CN111197300B (en) | 2022-02-18 |
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