CN113684848A - Construction process of steel cofferdam with deep water steep undulating rock surface - Google Patents
Construction process of steel cofferdam with deep water steep undulating rock surface Download PDFInfo
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- CN113684848A CN113684848A CN202111029772.4A CN202111029772A CN113684848A CN 113684848 A CN113684848 A CN 113684848A CN 202111029772 A CN202111029772 A CN 202111029772A CN 113684848 A CN113684848 A CN 113684848A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D19/00—Keeping dry foundation sites or other areas in the ground
- E02D19/02—Restraining of open water
- E02D19/04—Restraining of open water by coffer-dams, e.g. made of sheet piles
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
- E01D21/00—Methods or apparatus specially adapted for erecting or assembling bridges
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D15/00—Handling building or like materials for hydraulic engineering or foundations
- E02D15/02—Handling of bulk concrete specially for foundation or hydraulic engineering purposes
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D15/00—Handling building or like materials for hydraulic engineering or foundations
- E02D15/02—Handling of bulk concrete specially for foundation or hydraulic engineering purposes
- E02D15/06—Placing concrete under water
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
Abstract
The invention relates to a construction process of a steel cofferdam on a deep water steep undulating rock surface, which comprises the following construction steps: firstly, excavating a foundation trench on a deep-water steep rock surface; secondly, constructing drilled piles in the foundation trench at intervals; thirdly, accurately lowering the steel cofferdam into the foundation trench; fourthly, filling broken stones on the side slope outside the foundation trench; placing the stiffening section steel in the drilled pile, and pouring concrete in the steel cofferdam retaining wall; sixthly, lowering the steel casing, pouring bottom sealing concrete and constructing a cast-in-place pile; and seventhly, pumping water in the cofferdam and cutting off the steel pile casing. The steel cofferdam is fixed by the foundation trench, the leakage of cofferdam bulkhead concrete during pouring is avoided by filling broken stones in the side slope outside the foundation trench, the connection between the steel cofferdam and the riverbed is enhanced by the drilled piles arranged at intervals in the foundation trench, the concrete pouring amount of the bottom sealing layer can be effectively reduced, and the anti-floating force of the steel cofferdam can not meet the design requirement.
Description
Technical Field
The invention relates to the technical field of bridge construction, in particular to a construction process of a steel cofferdam on a deep-water steep undulating rock surface.
Background
At present, a large steel cofferdam is widely applied to construction of deepwater bridge engineering, but when the large steel cofferdam is applied to a steep deepwater rock surface without a covering layer, the cofferdam is inaccurate in sinking positioning, the cofferdam is easy to slide under external force, a large gap exists between the bottom of the cofferdam and the rock surface, so that the bottom sealing concrete cannot be well poured, and the like, so that the construction difficulty of bridge foundation engineering is increased, the danger coefficient is increased, the influence of river depth and flow velocity is increased, and the construction quality cannot be guaranteed.
In order to solve the technical problems in foundation engineering of deepwater steep and non-covering rock face bridges, the invention patent application with the publication number of CN 109113086B and the publication date of 2019, 8 and 20 discloses a construction method of a steel-concrete combined cofferdam of a deepwater bedrock exposed riverbed area; the steel-concrete combined cofferdam comprises an occlusive pile cofferdam and a double-wall steel cofferdam arranged at the top of the occlusive pile cofferdam. The river bed rock surface is fluctuant and has no covering layer, so that the positioning of the secant pile drill hole is difficult, the position precision of the top part after pile forming is small, and the stiffening section steel can not be ensured to be just positioned inside the steel cofferdam after the steel cofferdam sinks; the innovation of the patent is that the characteristic of good leakage resistance of the occlusive pile is utilized, if the pore-forming precision of the occlusive pile is poor, gaps possibly exist between the piles, and the permeability resistance is greatly reduced; the concrete surface after pouring still has the unevenness phenomenon, so that the concrete has the leakage phenomenon under the action of river impact force when the double-wall concrete is poured.
Disclosure of Invention
The invention aims to solve the problems, and provides a construction process of a deepwater steep undulating rock face steel cofferdam, which has high hole forming precision of a bored pile and is difficult to seep out when wall-clamped concrete is poured, so that the problems in the traditional construction technology are solved, the anti-overturning, anti-sliding and anti-floating bearing capacities of the cofferdam are increased, the pouring quality of bottom sealing concrete is ensured, the engineering construction quality is further ensured, the construction progress is accelerated, and the construction cost is reduced.
In order to achieve the purpose, the invention is realized by the following technical scheme: a construction process of a steel cofferdam on a deep water steep undulating rock surface comprises the following steps:
step one, excavating a foundation trench: designing the shape of the steel cofferdam according to the size of the bearing platform, excavating a foundation trench on the steep rock face in deep water, wherein the surface of the foundation trench runs along the steep trend of the rock face, the bottom surface of the foundation trench is smooth, and the foundation trench corresponds to the shape of the bottom of the steel cofferdam one by one; the width of the bottom surface of the foundation trench is greater than that of the bottom of the steel cofferdam;
step two, drilling pile construction: drilling piles are arranged at the center line of the foundation trench at intervals, the diameter of each drilling pile is smaller than the width of the bottom of the steel cofferdam, and the center of each drilling pile is positioned on the center line of the bottom of the steel cofferdam;
step three, lowering the steel cofferdam: sinking a construction steel cofferdam to the upper part of the underwater foundation trench from top to bottom according to a conventional cofferdam sinking construction method, wherein the center line of a cofferdam bottom bulkhead is coincided with the centers of all drilled piles, and the bottom of the steel cofferdam is just positioned at the pile tops of the drilled piles;
step four, filling the outer side slope of the foundation trench: filling broken stones on the outer side slope of the foundation trench; the particle size of broken stones below the slope outside the filling foundation trench and close to the drilled pile is smaller, so that concrete cannot seep out along a gap between the lower surface of the steel cofferdam and the bottom surface of the foundation trench when the wall-sandwiched concrete is poured, and the particle size of broken stones above the slope outside the filling foundation trench and close to the steel cofferdam is larger, so that displacement is avoided under the impact of river water;
placing stiffening section steel and pouring sandwich wall concrete: transferring stiffening section steel into the bored pile from the interior of the steel cofferdam, wherein the length of the stiffening section steel is greater than the depth of the bored pile; the lower part of the stiffening profile steel extends into the drilled pile, the upper part of the stiffening profile steel extends into the steel cofferdam, then the double-wall concrete is poured, and the steel cofferdam, the drilled pile and the stiffening profile steel are bonded into a whole through the double-wall concrete, so that the aim of stabilizing the steel cofferdam is fulfilled;
step six, bottom sealing concrete pouring and cast-in-place pile construction: lowering the steel casing to the top of the rock face through a guide frame arranged at the upper part of the steel cofferdam and fixing, pouring bottom sealing concrete under water, forming holes by using cast-in-place piles after the bottom sealing concrete reaches the designed strength, and lowering a reinforcement cage for pouring and forming;
pumping water in the steel cofferdam and cutting off the steel pile casing: and after the concrete in the cast-in-place pile reaches the designed strength, pumping out the water in the steel cofferdam, removing the steel support at the bottom of the steel cofferdam, breaking the concrete on the surface layer of the back cover concrete, cutting the steel casing, breaking the pile head, binding reinforcing steel bars of the bearing platform, and completing the concrete pouring of the bearing platform.
Furthermore, the surface of the foundation trench in the first step is arranged along the steep trend of the rock surface, both sides of the foundation trench are arranged to be side slopes with certain slopes, and the slopes of the side slopes outside the foundation trench increase in sequence along the steep trend of the rock surface.
Particularly, the section of the foundation trench is in an inverted trapezoid structure, the width of the bottom surface of the foundation trench is 30-40 cm larger than that of the bottom of the steel cofferdam, the center line of the bottom of the steel cofferdam coincides with that of the bottom surface of the foundation trench, and the slope gradient of the outer side slope of the foundation trench along the steep trend of the rock surface is 45-60 degrees and 30-45 degrees in sequence.
Further, the diameter and the depth of the drilled pile in the second step are the same, and the drilled pile is arranged along the steep trend of the rock surface in a different mode; the rock surface is divided into an upward slope, a downward slope, an upstream surface and a back surface along the steep trend of the rock surface and the trend of tides on the water surface; the number of the drilled piles arranged on the upper slope surface, the lower slope surface, the upstream surface and the back surface is calculated and determined according to the anti-floating bearing capacity of the steel cofferdam, the adhesive force of the steel cofferdam and the back cover concrete and the anti-floating capacity of the drilled piles; the distance between the drilled piles and the upper slope surface is smaller, the distance between the drilled piles and the lower slope surface is larger, and the distance between the drilled piles and the upper slope surface and the distance between the drilled piles and the lower slope surface are larger; the drilled piles are arranged on the upper slope surface and the lower slope surface at equal intervals, and the intervals of the drilled piles on the upstream surface and the downstream surface are reduced along with the reduction of the distance between the drilled piles and the river bank.
Furthermore, in the third step, if there is a construction error due to the position of the bored pile, so that the center of the bored pile is not located on the center line of the steel cofferdam, it should be ensured that the top surface of the bored pile is located inside the lower surface of the steel cofferdam, and at the same time, the lower surface of the steel cofferdam is ensured to be in close contact with the bottom surface of the foundation trench.
Furthermore, in the fifth step, the depth of the reinforced section steel penetrating into the bottom of the steel cofferdam is more than 30-40 cm, and the pouring height of the double-wall concrete is 2cm higher than that of the reinforced section steel; the stiffening section steel is made of I-shaped steel, channel steel, H-shaped steel or square steel;
compared with the prior art, the invention has the beneficial effects that:
1. the invention adopts the mode of excavating the rock surface layer into the foundation trench along the rock surface trend, thereby greatly reducing the adverse effects of large rock blasting amount and large environmental pollution in the traditional blasting construction process.
2. According to the invention, through excavation of the foundation trench, the anti-overturning and anti-sliding capabilities of the steel cofferdam after sinking under the action of adverse loads such as gravity and river impact force can be ensured to meet the requirements, the bottom of the cofferdam can be well contacted with the bottom surface of the foundation trench, and a larger gap can not be generated.
3. According to the invention, the gravels filled in the slope outside the foundation trench can effectively reduce the adverse effect of river impact force on the pouring of the concrete with the wall due to the adverse effect of the contact between the bottom of the steel cofferdam and the bottom surface of the foundation trench.
4. According to the invention, the connection force of the steel cofferdam and the rock face is increased by arranging the drilling piles at certain intervals, so that the volume of the bottom sealing concrete is greatly reduced, and the lower adhesion force between the bottom sealing concrete and the steel cofferdam caused by the thinner thickness of the bottom sealing concrete in the slope on the rock face is avoided, and further the anti-floating bearing capacity of the steel cofferdam cannot meet the design requirement.
5. Compared with the traditional double-wall steel cofferdam, the construction process of the steel cofferdam with the deep water steep fluctuating rock face greatly reduces the engineering difficulty, shortens the construction period, reduces the construction risk, controls the environmental pollution and saves the construction cost, thereby being a competitive construction process for the deep water steep fluctuating deep water foundation construction.
Drawings
FIG. 1 is a schematic elevation view of a steep relief rock face steel cofferdam of the present invention (after the pouring of double-walled concrete);
FIG. 2 is a schematic elevation view showing the connection relationship between the steel cofferdam and the bored pile according to the present invention;
FIG. 3 is a schematic plan view of a steep undulation rock face steel cofferdam of the present invention;
FIG. 4 is a schematic elevation view of a steep undulating rock face steel cofferdam of the present invention (after cast-in-place pile construction);
fig. 5 is a schematic elevation view of the steep undulating rock face steel cofferdam of the present invention (after the construction of the bearing platform).
Reference numbers in the figures: 1 foundation trench, 1b, 1c foundation trench outer side slope, 2 drilled piles, 3 fluctuating rock face, 3a upper slope face, 3b lower slope face, 3c upstream face, 3d backing face, 4 broken stones, 5 stiffening section steel, 6 double-wall concrete, 7 back cover concrete, 8 cast-in-place pile, 9 steel cofferdam, 10 steel pile casing, 11 bottom steel support and 12 bearing platform.
Detailed Description
The invention will be further described in detail with reference to examples of embodiments shown in the drawings to which, however, the invention is not restricted.
When the construction of a large steel cofferdam in a deepwater bridge engineering is applied to a steep deepwater and non-overburden rock face, the sinking positioning of the cofferdam is inaccurate due to the steep trend of the rock face surface, the problem that the rock blasting amount in the blasting construction process is large and the adverse effect on environmental pollution is large exists in the construction of the existing large steel cofferdam is shown in figures 1, 2 and 3, the anti-overturning and anti-sliding capacity of the steel cofferdam can meet the requirement under the adverse load action of gravity, river impact force and the like after the steel cofferdam is sunk mainly through the excavation of a foundation trench, the bottom of the cofferdam can be in good contact with the bottom surface of the foundation trench, and a larger gap cannot be generated; the construction principle is as follows:
excavating a foundation trench: designing the shape of the steel cofferdam 9 according to the size of the bearing platform 12, excavating a foundation trench 1 on the deep-water steep rock surface 3, wherein the surface of the foundation trench 1 runs along the steep trend of the rock surface 3, and the bottom surface of the foundation trench 1 is smooth and corresponds to the shape of the bottom of the steel cofferdam 9 one by one; the width of the bottom surface of the foundation trench 1 is larger than that of the bottom of the steel cofferdam 9;
it is worth noting that: the surface of the foundation trench 1 is arranged along the steep trend of the rock surface 3, both sides of the foundation trench are provided with side slopes (1 b, 1 c) with certain gradients, and the gradients of the outer side slopes (1 b, 1 c) of the foundation trench are sequentially increased along the steep trend of the rock surface 3; the slope of a foundation trench outer side slope 1c formed by the upper rock face and the foundation trench along the steep trend of the rock face 3 is smaller than that of a foundation trench outer side slope 1b formed by the lower rock face and the foundation trench; the section of the foundation trench 1 is in an inverted trapezoidal structure, the width of the bottom surface of the foundation trench 1 is 30-40 cm larger than that of the bottom of the steel cofferdam 9, the center line of the bottom of the steel cofferdam 9 is superposed with that of the bottom surface of the foundation trench 1, and the slope (1 b, 1 c) of the outer side of the foundation trench 1 along the steep trend of the rock surface 3 is 45-60 degrees and 30-45 degrees in sequence;
and (3) construction of a drilled pile: drilling piles 2 are arranged at the center line position of the foundation trench 1 at intervals, the diameter of each drilling pile 2 is smaller than the width of the bottom of the steel cofferdam 9, and the center of each drilling pile 2 is positioned on the center line of the bottom of the steel cofferdam 9;
to the setting of bored pile 2 and 3 position relations of rock face: the diameter and the depth of the drilled piles 2 are the same, and the drilled piles are arranged along the steep trend of the rock surface 3 in a different mode; the rock face 3 is divided into an upper slope 3a, a lower slope 3b, an upstream face 3c and a back face 3d along the steep trend of the rock face and the tide trend of the water surface; the number of the bored piles 2 arranged on the upper slope surface 3a, the lower slope surface 3b, the upstream surface 3c and the back surface 3d is calculated and determined according to the anti-floating bearing capacity of the steel cofferdam 9, the adhesive force of the steel cofferdam 9 and the back cover concrete 7 and the anti-floating capacity of the bored piles 2; the distance between the drilled piles 2 and the upper slope surface 3a is smaller, the distance between the drilled piles 2 and the lower slope surface 3b is larger, and the distance between the drilled piles and the upstream surface 3c and the downstream surface 3d is between the drilled piles and the lower slope surface; the bored piles 2 are arranged at equal intervals on the upper slope 3a and the lower slope 3b, and the intervals between the bored piles on the upstream surface 3c and the downstream surface 3d decrease as the distance from the bored piles to the bank decreases.
The steel cofferdam 9 is put down: according to a conventional cofferdam sinking construction method, sinking a construction steel cofferdam 9 to the upper part of an underwater foundation trench 1 from top to bottom, wherein the center line of a bulkhead at the bottom of the cofferdam 9 is coincided with the centers of all drilled piles 2, and the bottom of the steel cofferdam 9 is just positioned at the pile top of the drilled pile 2; if construction errors exist in the positions of the bored piles 2, so that the centers of the bored piles 2 are not located on the central line of the steel cofferdam 9, the top surfaces of the bored piles 2 are all located inside the lower surface of the steel cofferdam 9, and the lower surface of the steel cofferdam 9 is ensured to be in close contact with the bottom surface of the foundation trench 1.
In order to effectively reduce the adverse effect of river impact force on the pouring of the concrete with the included wall caused by the adverse effect of the contact between the bottom of the steel cofferdam and the bottom surface of the foundation trench, the invention fills the concrete with the included wall through the slope outside the foundation trench:
filling broken stones 4 on the outer side slope of the foundation trench 1; the particle size of the broken stones 4 below the outer side slopes (1 b and 1 c) of the filling foundation groove and close to the drilled piles 2 is small, so that the concrete cannot seep out along the gap between the lower surface of the steel cofferdam 9 and the bottom surface of the foundation groove 1 when the wall-sandwiched concrete 6 is poured, the particle size of the broken stones 4 above the outer side slopes (1 b and 1 c) of the filling foundation groove and close to the steel cofferdam 9 is large, and the displacement is avoided under the impact of river water;
in addition in order to increase the power of being connected of steel cofferdam and rock face to reduce back cover concrete square volume by a wide margin, it is lower to avoid in the rock face side slope because of the bonding power that back cover concrete and steel cofferdam caused by back cover concrete thickness is thinner, sets up the bored pile through setting up the interval, realizes in the bored pile is transferred into from steel cofferdam inside to the shaped steel 5 that will put more energy into: placing stiffening section steel and pouring sandwich wall concrete: transferring the stiffening section steel 5 into the bored pile 2 from the inside of the steel cofferdam 9, wherein the length of the stiffening section steel 5 is greater than the depth of the bored pile 2; the lower part of the stiffening profile steel 5 extends into the drilled pile 2, the upper part of the stiffening profile steel extends into the steel cofferdam 9, then the double-wall concrete 6 is poured, and the steel cofferdam 9, the drilled pile 2 and the stiffening profile steel 5 are bonded into a whole through the double-wall concrete 6, so that the purpose of stabilizing the steel cofferdam 9 is achieved;
so far, the steel cofferdam finishes construction, and the following construction is the bearing platform:
referring to fig. 4, the bottom sealing concrete pouring and the cast-in-place pile construction: the steel pile casing 10 is lowered to the top of the rock face 3 through a guide frame arranged on the upper portion of a steel cofferdam 9 and fixed, the back cover concrete 7 is poured underwater, after the back cover concrete 7 reaches the design strength, a bored concrete pile 8 is formed into a hole, and a reinforcement cage is lowered for pouring forming;
referring to fig. 5, the water pumping and steel casing cutting in the steel cofferdam: after the concrete in the cast-in-place pile 8 reaches the designed strength, pumping out the water in the steel cofferdam 9, removing the bottom steel support 11 of the steel cofferdam 9, breaking the concrete on the surface layer of the bottom-sealed concrete, cutting the steel casing 10, breaking the pile head, binding the reinforcing steel bars of the bearing platform 12, and completing the concrete pouring of the bearing platform 12;
the steel cofferdam constructed by the construction process has the advantages of obviously enhanced anti-overturning, anti-sliding and anti-permeation capabilities, obviously reduced engineering construction difficulty, construction cost and risk degree, suitability for construction of the existing deep water fluctuating rock face steel cofferdam or improvement of similar construction structures, and obvious economic and social benefits.
The above-mentioned embodiments are only for convenience of description, and are not intended to limit the present invention in any way, and those skilled in the art will understand that the technical features of the present invention can be modified or changed by other equivalent embodiments without departing from the scope of the present invention.
Claims (6)
1. A construction process of a steel cofferdam on a deep water steep undulating rock surface is characterized in that: the method comprises the following steps:
step one, excavating a foundation trench: designing the shape of the steel cofferdam according to the size of the bearing platform, excavating a foundation trench on the steep rock face in deep water, wherein the surface of the foundation trench runs along the steep trend of the rock face, the bottom surface of the foundation trench is smooth, and the foundation trench corresponds to the shape of the bottom of the steel cofferdam one by one; the width of the bottom surface of the foundation trench is greater than that of the bottom of the steel cofferdam;
step two, drilling pile construction: drilling piles are arranged at the center line of the foundation trench at intervals, the diameter of each drilling pile is smaller than the width of the bottom of the steel cofferdam, and the center of each drilling pile is positioned on the center line of the bottom of the steel cofferdam;
step three, lowering the steel cofferdam: sinking a construction steel cofferdam to the upper part of the underwater foundation trench from top to bottom according to a conventional cofferdam sinking construction method, wherein the center line of a cofferdam bottom bulkhead is coincided with the centers of all drilled piles, and the bottom of the steel cofferdam is just positioned at the pile tops of the drilled piles;
step four, filling the outer side slope of the foundation trench: filling broken stones on the outer side slope of the foundation trench; the particle size of broken stones below the slope outside the filling foundation trench and close to the drilled pile is smaller, so that concrete cannot seep out along a gap between the lower surface of the steel cofferdam and the bottom surface of the foundation trench when the wall-sandwiched concrete is poured, and the particle size of broken stones above the slope outside the filling foundation trench and close to the steel cofferdam is larger, so that displacement is avoided under the impact of river water;
placing stiffening section steel and pouring sandwich wall concrete: transferring stiffening section steel into the bored pile from the interior of the steel cofferdam, wherein the length of the stiffening section steel is greater than the depth of the bored pile; the lower part of the stiffening profile steel extends into the drilled pile, the upper part of the stiffening profile steel extends into the steel cofferdam, then the double-wall concrete is poured, and the steel cofferdam, the drilled pile and the stiffening profile steel are bonded into a whole through the double-wall concrete, so that the aim of stabilizing the steel cofferdam is fulfilled;
step six, bottom sealing concrete pouring and cast-in-place pile construction: lowering the steel casing to the top of the rock face through a guide frame arranged at the upper part of the steel cofferdam and fixing, pouring bottom sealing concrete under water, forming holes by using cast-in-place piles after the bottom sealing concrete reaches the designed strength, and lowering a reinforcement cage for pouring and forming;
pumping water in the steel cofferdam and cutting off the steel pile casing: and after the concrete in the cast-in-place pile reaches the designed strength, pumping out the water in the steel cofferdam, removing the steel support at the bottom of the steel cofferdam, breaking the concrete on the surface layer of the back cover concrete, cutting the steel casing, breaking the pile head, binding reinforcing steel bars of the bearing platform, and completing the concrete pouring of the bearing platform.
2. The construction process of the steel cofferdam for the deep water steep undulating rock surface according to claim 1, characterized in that: in the first step, the surface of the foundation trench is arranged along the steep trend of the rock surface, both sides of the foundation trench are provided with side slopes with certain slopes, and the slopes of the side slopes outside the foundation trench increase in sequence along the steep trend of the rock surface.
3. The construction process of the steel cofferdam with the deep water steep undulating rock surface as claimed in claim 2, wherein: the foundation trench is of an inverted trapezoidal structure in cross section, the width of the bottom surface of the foundation trench is 30-40 cm larger than that of the bottom of the steel cofferdam, the center line of the bottom of the steel cofferdam coincides with that of the bottom surface of the foundation trench, and the slope gradient of the outer side slope of the foundation trench along steep trend of rock surface is 45-60 degrees and 30-45 degrees in sequence.
4. The construction process of the steel cofferdam for the deep water steep undulating rock surface according to claim 1, characterized in that: in the second step, the diameter and the depth of the drilled pile are the same, and the drilled pile is arranged along the steep trend of the rock surface in a different mode; the rock surface is divided into an upward slope, a downward slope, an upstream surface and a back surface along the steep trend of the rock surface and the trend of tides on the water surface; the number of the drilled piles arranged on the upper slope surface, the lower slope surface, the upstream surface and the back surface is calculated and determined according to the anti-floating bearing capacity of the steel cofferdam, the adhesive force of the steel cofferdam and the back cover concrete and the anti-floating capacity of the drilled piles; the distance between the drilled piles and the upper slope surface is smaller, the distance between the drilled piles and the lower slope surface is larger, and the distance between the drilled piles and the upper slope surface and the distance between the drilled piles and the lower slope surface are larger; the drilled piles are arranged on the upper slope surface and the lower slope surface at equal intervals, and the intervals of the drilled piles on the upstream surface and the downstream surface are reduced along with the reduction of the distance between the drilled piles and the river bank.
5. The construction process of the steel cofferdam for the deep water steep undulating rock surface according to claim 1, characterized in that: in the third step, if construction errors exist in the positions of the bored piles, so that the centers of the bored piles are not located on the central line of the steel cofferdam, the top surfaces of the bored piles are all located inside the lower surface of the steel cofferdam, and the lower surface of the steel cofferdam is ensured to be in close contact with the bottom surface of the foundation trench.
6. The construction process of the steel cofferdam for the deep water steep undulating rock surface according to claim 1, characterized in that: in the fifth step, the depth of the stiffened steel section penetrating into the bottom of the steel cofferdam is more than 30-40 cm, and the pouring height of the wall-clamped concrete is 2cm higher than that of the stiffened steel section; the stiffening section steel is made of I-shaped steel, channel steel, H-shaped steel or square steel.
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| CN209508992U (en) * | 2018-12-11 | 2019-10-18 | 中铁五局集团贵州工程有限公司 | A kind of underwater embedding rock steel sheet pile cofferdam structure |
| CN111608173A (en) * | 2020-06-04 | 2020-09-01 | 石家庄铁道大学 | Construction method and device for deep water steep slope bare rock drilled pile |
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2021
- 2021-09-03 CN CN202111029772.4A patent/CN113684848B/en active Active
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000192469A (en) * | 1998-12-25 | 2000-07-11 | Kajima Corp | Cofferdam device used for double wall cofferdam construction method, and double wall cofferdam construction method |
| CN101358453A (en) * | 2008-08-21 | 2009-02-04 | 中铁大桥局股份有限公司 | Composite boxed cofferdam and building method thereof |
| CN209508992U (en) * | 2018-12-11 | 2019-10-18 | 中铁五局集团贵州工程有限公司 | A kind of underwater embedding rock steel sheet pile cofferdam structure |
| CN111608173A (en) * | 2020-06-04 | 2020-09-01 | 石家庄铁道大学 | Construction method and device for deep water steep slope bare rock drilled pile |
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| CN113684848B (en) | 2023-01-31 |
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