CN114892690B - Construction method of double-wall steel sleeve cofferdam - Google Patents
Construction method of double-wall steel sleeve cofferdam Download PDFInfo
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- CN114892690B CN114892690B CN202210572196.6A CN202210572196A CN114892690B CN 114892690 B CN114892690 B CN 114892690B CN 202210572196 A CN202210572196 A CN 202210572196A CN 114892690 B CN114892690 B CN 114892690B
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 151
- 239000010959 steel Substances 0.000 title claims abstract description 151
- 238000010276 construction Methods 0.000 title claims abstract description 72
- 238000000034 method Methods 0.000 claims abstract description 42
- 239000004576 sand Substances 0.000 claims abstract description 31
- 230000008569 process Effects 0.000 claims abstract description 29
- 239000002689 soil Substances 0.000 claims abstract description 19
- 238000005086 pumping Methods 0.000 claims abstract description 17
- 238000005553 drilling Methods 0.000 claims abstract description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 22
- 239000004927 clay Substances 0.000 claims description 15
- 230000001681 protective effect Effects 0.000 claims description 14
- 238000009412 basement excavation Methods 0.000 claims description 11
- 238000009434 installation Methods 0.000 claims description 4
- 229910003460 diamond Inorganic materials 0.000 claims description 3
- 239000010432 diamond Substances 0.000 claims description 3
- 239000000843 powder Substances 0.000 claims description 3
- 238000004080 punching Methods 0.000 claims description 3
- 230000007246 mechanism Effects 0.000 description 4
- 239000011435 rock Substances 0.000 description 4
- 230000035515 penetration Effects 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 239000002893 slag Substances 0.000 description 2
- 206010008190 Cerebrovascular accident Diseases 0.000 description 1
- 208000006011 Stroke Diseases 0.000 description 1
- 238000004873 anchoring Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000010408 sweeping Methods 0.000 description 1
Classifications
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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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/20—Hydro energy
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- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Paleontology (AREA)
- Civil Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Structural Engineering (AREA)
- Placing Or Removing Of Piles Or Sheet Piles, Or Accessories Thereof (AREA)
Abstract
The invention belongs to the technical field of cofferdams for hydraulic engineering, and provides a double-wall steel sleeve box cofferdam construction method, which comprises the following steps: step S1, after pile foundation construction is completed, removing a drilling platform; step S2, erecting a hole guiding platform, performing hole guiding construction around the hole guiding platform by adopting a rotary digging machine so as to form a ring groove matched with the bottom of the cofferdam on a riverbed, wherein the depth of the hole guiding is not higher than the elevation position of the designed bottom of the cofferdam, backfilling sand after hole guiding is completed, and backfilling the sand to the elevation of the riverbed so as to replace a rock-soil layer at the designed lowering position of the cofferdam with sand; step S3, splicing and lowering the double-wall steel sleeve cofferdam sections in sequence; s4, pumping and excavating operation is carried out, and a plurality of layers of internal supports are arranged in the cofferdam; and S5, pouring back cover concrete. According to the invention, before the cofferdam is lowered, hole guiding, slotting and soil taking operations are performed in advance, and a rock-soil layer at the lowered position of the cofferdam design is replaced by sand; in the subsequent cofferdam lowering process, the lowering resistance is small, so that the cofferdam can be quickly and smoothly lowered in place.
Description
Technical Field
The invention belongs to the technical field of cofferdams for hydraulic engineering, and particularly relates to a double-wall steel sleeve box cofferdam construction method.
Background
At present, a suction mud sinking process is generally adopted to lower the cofferdam during cofferdam construction. However, when the clay layer is thicker in the rock soil layer where the main pier is located, the suction dredge is difficult; at this time, the cofferdam is lowered by adopting the suction mud sinking process, which results in low cofferdam lowering efficiency. In addition, construction time is generally limited, which results in great difficulty in construction organization and quality control. Therefore, the existing cofferdam lowering construction method is not suitable for cofferdam construction when the clay layer in the rock-soil layer where the main pier is located is thicker.
For example, the main pier 3# of the main bridge of the ultra-large bridge of the Huanhuai-guan river is positioned in the south-side water area of the Fengyang county-huai-guan-zhen river, and the rock and soil layers are mainly silt filled soil, cohesive soil, pebbles and gneiss. The average thickness of the covering soil layer is about 8.37m; the average thickness of the fully weathered gneiss strip was about 15.49m; the average thickness of the fragment-shaped strong-weathering gneiss strips is about 19.07m; the mean thickness of the apoplexy cured gneiss tape was about 19.87m. The pile end is suitable for deep embedding, the full-strong wind-driven bottom interface fluctuates along with the fluctuation of the terrain, the soil layer and the strong wind-driven bedrock are broken, the bearing capacity is low, the pile end is not suitable for being used as a foundation bearing layer, the rock core of the wind-driven bedrock is complete, and the bearing capacity is high. The construction of the 3# main pier double-wall steel sleeve box cofferdam has the following construction difficulties: 1. deep penetration: the average elevation of the river bed of the 3# main pier cofferdam is about +3m, the elevation of the bottom of the cofferdam is-10.8 m, the elevation of the bottom of the bearing platform is-6 m, the elevation of the bottom sealing is-10 m, and the river bed is required to be dug out 13m. The highest design water level of the cofferdam is +18.5m, and the water head difference is 28.5m. 2. And (3) excavation difficulty: in the 3# main pier cofferdam lowering process, the mucky soil, the powdery clay, the clay and the pebble layer are required to be penetrated, and finally the mucky soil enters the fully weathered gneiss, so that the clay layer is thicker.
Accordingly, there is a need to provide an improved solution to the above-mentioned deficiencies of the prior art.
Disclosure of Invention
The invention aims to provide a double-wall steel sleeve cofferdam construction method which can solve the defects in the prior art.
In order to achieve the above object, the present invention provides the following technical solutions:
a double-wall steel sleeve cofferdam construction method comprises the following steps:
step S1, after pile foundation construction is completed, removing a drilling platform;
step S2, erecting a hole guiding platform, performing hole guiding construction around the hole guiding platform by adopting a rotary digging machine so as to form a ring groove matched with the bottom of the cofferdam on a riverbed, wherein the depth of the hole guiding is not higher than the elevation position of the design bottom of the cofferdam, backfilling sand after hole guiding is completed, and backfilling the sand to the elevation of the riverbed so as to replace a rock-soil layer at the position where the cofferdam is designed to be lowered with sand;
step S3, splicing and lowering the double-wall steel sleeve cofferdam sections in sequence;
s4, pumping and excavating operation is carried out, and a plurality of layers of internal supports are arranged in the cofferdam;
and S5, pouring back cover concrete.
In the double-wall steel box cofferdam construction method as described above, preferably, in step S2, the ring grooves are formed by connecting a plurality of holes, adjacent holes are meshed with each other, and the meshing width is not smaller than the wall thickness of the cofferdam.
In the double-wall steel box cofferdam construction method as described above, preferably, in step S2, hole-by-hole is sequentially performed during hole-guiding construction, and the specific construction steps of the single hole are as follows:
step S201, firstly, punching a pilot hole casing;
step S202, performing drilling operation in the hole guiding pile casing;
step S203, a crescent protection barrel is put down in the hole guiding protection barrel;
step S204, sand is backfilled into the crescent protective cylinder;
step S205, pulling out the hole guiding pile casing; the crescent protective cylinder is reserved, so that the concave side of the crescent protective cylinder is used as a guide for installing the hole guiding protective cylinder when the corresponding next adjacent hole site is constructed;
in the whole hole guiding construction process in the step S2, each bearing platform uses two crescent protection cylinders and one hole guiding protection cylinder in a common cycle mode;
and after the hole guiding construction of the next adjacent hole site is completed, the crescent protection barrel corresponding to the previous hole site is pulled out.
In the double-wall steel box cofferdam construction method as described above, it is preferable that a horizontally disposed guide frame for guiding the hole guiding casing is installed first before step S201 to prevent the hole guiding casing from being deviated.
In the double-wall steel box cofferdam construction method as described above, preferably, step S202, different drill penetration rates are selected according to geological conditions during the drilling process.
In the double-wall steel box cofferdam construction method as described above, preferably, the step S3 specifically includes the steps of:
step S301, removing the hole guiding platform, and installing an assembly platform on the steel casing;
s302, splicing a first-section double-wall steel cofferdam on the splicing platform, installing a lifting system at the top of the steel pile casing, and installing a guide system at the periphery of the steel pile casing, wherein the guide system is in guide fit with the inner wall of the first-section double-wall steel cofferdam; the first-section double-wall steel cofferdam is lifted through the lifting system, a part of the assembly platform, which is blocked from being lowered, is removed, and then the first-section double-wall cofferdam is lowered by the lifting system;
and step S303, assembling and lowering the subsequent double-wall steel cofferdams.
In the double-wall steel box cofferdam construction method as described above, preferably, in step S303: and in the lowering process of each section of double-wall steel cofferdam, the whole double-wall steel cofferdam is lowered by adopting the lifting system, and the double-wall steel cofferdam is lowered in an auxiliary manner by carrying out sand sucking operation at the bottom of a river bed and increasing the dead weight of the cofferdam.
In the double-wall steel box cofferdam construction method as described above, preferably, in step S4, the concrete method of the water pumping excavation operation is as follows: firstly, temporarily fixing the top of the double-wall steel sleeve cofferdam and the steel casing, then pumping water in the double-wall steel sleeve cofferdam by adopting a water pump, and then sucking mud for excavation;
in the suction dredge excavation process, according to the difference of the geological conditions of pier position department, it is to adopt different modes: dredging, namely excavating by adopting a gas lift reverse circulation mud suction method, and pumping the mud to a mud boat; the powder clay layer is excavated by adopting an excavator, meanwhile, the clay is loosened by matching with manpower, and then the excavated clay is transported outwards by adopting a grab bucket excavator;
and in the water pumping and excavating process, each layer of the inner support is lowered.
In the double-wall steel box cofferdam construction method as described above, preferably, the installation sequence of the plurality of layers of the inner supports follows the principle of going up and down.
In the double-wall steel box cofferdam construction method, preferably, the cross section of the double-wall steel box cofferdam is square;
each layer of inner support is of a diamond structure inscribed in the middle of each side wall of the double-wall steel sleeve cofferdam.
The beneficial effects are that: for the rock soil layer with thicker clay layer, the cofferdam is put down in-process: according to the invention, before the cofferdam is lowered, hole guiding, slotting and soil taking operations are performed in advance, and a rock-soil layer at the lowered position of the cofferdam design is replaced by sand; in the subsequent cofferdam lowering process, the lowering resistance is small, so that the cofferdam can be quickly and smoothly lowered in place. Compared with a method for lowering the cofferdam through a suction mud sinking process, the method greatly improves the speed of lowering the cofferdam, reduces the construction difficulty and shortens the construction period.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. Wherein:
FIG. 1 is a schematic view of the installation position of a guide frame in the present invention;
FIG. 2 is a schematic illustration of the mating of a guide frame and a pilot cartridge of the present invention;
FIG. 3 is a schematic illustration of backfilling sand into a pilot casing in accordance with the present invention;
FIG. 4 is a view showing the layout of the pilot holes in the present invention;
FIG. 5 is a schematic illustration of the cooperation of a crescent shaped casing and a pilot hole casing in accordance with the present invention;
FIG. 6 is a schematic diagram of a pilot hole construction in accordance with the present invention;
FIG. 7 is a schematic view of the lowering of the first section double wall steel cofferdam of the present invention;
FIG. 8 is a plan view of the hoist system of the present invention;
FIG. 9 is a schematic view of the structure of the inner support of the present invention;
fig. 10 is a schematic structural view of a double-wall steel box cofferdam of the present invention.
The names corresponding to the reference numerals in the figures are: 1-first-section double-wall steel cofferdam; 2-a second section double-wall steel cofferdam; 3-a third section of double-wall steel cofferdam; 4-single-wall steel cofferdam; 5-steel casing; 51-angle pile steel pile casing; 52-edge middle steel pile casing; 6-guiding system; 7-a lifting system; 71-lifting points; 72-a lower hanging point; 73-lowering the beam; 74-boom; 75-anchoring brackets; 8-inner support; 9-wall warehouse boards; 10-wall bin; 11-side panel A; 12-side plate B; 13-an assembly platform; 14-a hole guiding platform; 15-a guide frame; 16-trestle platform; 17-trestle pipe piles; 18-hole guiding pile casing; 19-crescent shaped protective cylinder; 191-limit steel plate clip.
Detailed Description
The following description of the technical solutions in the embodiments of the present invention will be clear and complete, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which are derived by a person skilled in the art based on the embodiments of the invention, fall within the scope of protection of the invention.
In the description of the present invention, the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", etc. refer to the orientation or positional relationship based on that shown in the drawings, merely for convenience of description of the present invention and do not require that the present invention must be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention. The terms "coupled" and "connected" as used herein are to be construed broadly and may be, for example, fixedly coupled or detachably coupled; either directly or indirectly through intermediate components, the specific meaning of the terms being understood by those of ordinary skill in the art as the case may be.
The invention will be described in detail below with reference to the drawings in connection with embodiments. It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.
As shown in fig. 1 to 10, a double-wall steel casing cofferdam construction method comprises the following steps:
and S1, after pile foundation construction is completed, removing the drilling platform.
And S2, erecting a hole guiding platform 14, performing hole guiding construction around the hole guiding platform 14 by adopting a rotary digging machine so as to form a ring groove matched with the bottom of the cofferdam on the riverbed, wherein the depth of the hole guiding is not higher than the elevation position of the design bottom of the cofferdam, backfilling sand after hole guiding is completed, and backfilling to the elevation of the riverbed so as to replace a rock-soil layer at the position where the cofferdam is designed to be lowered with sand.
Step S3, splicing and lowering the double-wall steel sleeve cofferdam sections in sequence; specifically, the double-wall steel sleeve cofferdam can be lowered in two sections, three sections, four sections, five sections or six sections.
And S4, carrying out water pumping excavation operation, and installing a plurality of layers of inner supports 8 in the cofferdam.
And S5, pouring back cover concrete.
In an alternative embodiment of the present invention, in step S2, the ring groove is formed by connecting a plurality of holes, adjacent holes are meshed with each other, and the meshing width is not smaller than the wall thickness of the cofferdam. Specifically, the plurality of holes are communicated with each other to form the ring groove.
In an alternative embodiment of the present invention, in step S2, hole-by-hole construction is performed sequentially, and specific construction steps of the single hole are as follows:
step S201, firstly, punching a hole guiding protective cylinder 18 to prevent hole collapse;
step S202, performing drilling operation in the hole guiding casing 18;
step S203, a crescent protection barrel 19 is lowered to the designed elevation in the hole guiding protection barrel 18, and limit steel plate clips 191 are arranged on two sides of the top of the crescent protection barrel 19 so as to prevent the crescent protection barrel 19 from rotating and ensure the position accuracy of the crescent protection barrel 19;
step S204, sand is backfilled into the crescent protective cylinder 19; specifically, the dump truck conveys sand to an operation platform, the excavator is matched with the bucket string to backfill the sand into the hole through the embedded hole guiding pile casing 18, and the self-compaction of the sand is utilized to sink under the action of self weight and backfill the sand to the original river bed elevation;
in step S205, the hole guiding casing 18 is pulled out, and the crescent casing 19 is reserved, so that the concave side of the crescent casing 19 is used as the guide for installing the hole guiding casing 18 when the corresponding next adjacent hole is constructed.
Preferably, in the whole hole guiding construction process of step S2, each bearing platform is provided with two crescent-shaped protecting cylinders 18 and one circular hole guiding protecting cylinder 18, and is recycled. After the hole guiding construction of the next adjacent hole position is completed, the crescent protection barrel 18 corresponding to the previous hole position is pulled out.
In the step S2, each bearing platform is provided with two crescent protection barrels 18 and one circular hole guiding protection barrel 18, and is recycled, and the specific construction method of hole guiding construction is as follows:
(1) Hole guiding construction of the 1 st hole site is carried out: inserting a pilot hole casing 18 into a preset 1 st hole site; then, performing drilling operation in the hole guiding pile casing; then, a first crescent protection cylinder 19 is put down in the guiding hole protection cylinder; then, sand is backfilled into the first crescent protection barrel; then the leading hole protection cylinder is pulled out, and the first crescent protection cylinder 19 is reserved, so that the concave side of the crescent protection cylinder corresponding to the 1 st hole site is used as the guide of the 2 nd hole site for installing the leading hole protection cylinder;
(2) Hole guiding construction of the 2 nd hole is carried out: inserting a hole guiding protective cylinder into the 2 nd hole site, and then carrying out hole digging operation; a crescent protective cylinder is put down in the guide hole protective cylinder corresponding to the 2 nd hole site; then backfilling sand into the crescent protection barrel corresponding to the 2 nd hole site; then the leading hole protection cylinder corresponding to the 2 nd hole site and the crescent protection cylinder corresponding to the 1 st hole site are pulled out;
(3) And repeating the steps, and sequentially carrying out the subsequent construction of each hole site until the hole guiding construction of all the hole sites is completed.
In other embodiments, multiple pilot hole casings may be employed during pilot hole construction; when all the hole sites are completed to guide holes, the crescent protection cylinders 19 are taken out.
In an alternative embodiment of the present invention, before step S201, the horizontally disposed guide frame 15 is first installed to guide the hole guiding casing 18, so as to prevent the hole guiding casing 18 from being deviated, and ensure the casing verticality. The guide frame 15 is positioned accurately, and the verticality and depth of the guide hole slotting are ensured. The guide frame 15 is located between the landing stage platform 16 and the hole guiding platform 14.
Specifically, the guide frame 15 is fixedly arranged between the steel pile casing 5 and the trestle pipe pile 17; the mounting process is that corbels are correspondingly welded between the steel pile casing 5 and the trestle pipe piles 17, and then the guide frame 15 is fixedly arranged on the corbels.
In an alternative embodiment of the present invention, step S202, selecting different drill penetration rates according to geological conditions during the drilling process, specifically:
when the soft stratum is changed into the hard stratum, the slow-going is required to be slowed down;
in the stratum easy to shrink, the hole sweeping times are properly increased to prevent the shrinkage;
in the hard plastic layer, drilling is performed at a high rotating speed so as to improve the drilling efficiency;
the sand layer is drilled slowly at a slow rotating speed;
if pebble layer appears in the actual construction process, the following measures are taken: and (3) slowly drilling the pebble layer with smaller grain size by adopting a bucket type drill bit, and replacing the bucket type drill bit to remove slag after drilling the pebble layer with larger grain size by adopting a conical spiral drill bit, so that the pebble layer is reciprocated until the pebble layer is penetrated. The drill slag is transported to a construction site at time and abandoned to a proper place to meet the requirement of environmental protection.
In an alternative embodiment of the invention, wall bin plates 9 are arranged in each section of double-wall steel cofferdam, and the double-wall steel cofferdam is divided into a plurality of wall bins 10 by arranging the wall bin plates 9.
In an alternative embodiment of the present invention, step S3 specifically includes the steps of:
step S301, removing the hole guiding platform 14, and installing the assembly platform 13 on the steel casing 5.
Step S302, assembling the first-section double-wall steel cofferdam 1 on an assembling platform 13, then installing a lifting system 7 at the top of a steel pile casing 5, installing a guide system 6 at the periphery of the steel pile casing 5, and guiding and matching the guide system 6 with the inner wall of the first-section double-wall steel cofferdam 1; the first-section double-wall steel cofferdam 1 is lifted by the lifting system 7, the part of the assembly platform 13 which is blocked from being lowered is removed, and then the first-section double-wall cofferdam is lowered by the lifting system 7.
The guide system 6 comprises a horizontal mechanism, one end of the horizontal mechanism is fixedly connected with the periphery of the steel casing 5, and the other end of the horizontal mechanism is rotatably provided with rollers so as to roll along the inner wall of the double-wall steel casing cofferdam. The horizontal mechanism is double-spliced I-steel, the double-spliced I-steel is welded together by adopting a steel plate (the thickness is 1 cm), and a rolling shaft for a rolling wheel is arranged at one end of the double-spliced I-steel.
The center line of the guide system 6 is radially consistent with the steel casing 5, and a gap (for example, 15mm, 18mm, 20mm, 22mm or 25 mm) of 15mm-25mm is reserved between the guide system 6 and the inner wall of the double-wall steel casing cofferdam, so that a rolling friction system is formed.
And step S303, assembling and lowering the subsequent double-wall steel cofferdams.
In an alternative embodiment of the present invention, step S303 is specifically: the subsequent double-wall steel cofferdam assembly is carried out on the top of the corresponding previous double-wall steel cofferdam;
in the lowering process of each section of double-wall steel cofferdam, the whole double-wall steel cofferdam is lowered by adopting a lifting system 7, and the double-wall steel cofferdam is lowered in an auxiliary way by carrying out sand sucking operation at the bottom of a river bed and increasing the dead weight of the cofferdam. The method for adding the dead weight of the cofferdam can be to pour wall cabin concrete or water injection into the wall cabin. Preferably, the method for adding the dead weight of the cofferdam can be to pour wall warehouse concrete into the wall warehouse, wherein the wall warehouse concrete is C30 concrete.
In an alternative embodiment of the invention, after the final section of double-wall steel cofferdam is lowered, single-wall steel cofferdam 4 is assembled on top of the final section of double-wall steel cofferdam. The single-wall steel cofferdam 4 has the function of wave resistance, prevents water level change caused by weather reasons, and improves the safety use performance of the cofferdam.
In an optional embodiment of the present invention, in step S4, the concrete method of the water pumping excavation operation is: firstly, temporarily fixing the top of a double-wall steel sleeve cofferdam and a steel casing 5, then pumping out water in the double-wall steel sleeve cofferdam by adopting a water pump, and then sucking mud for excavation;
in the suction dredge excavation process, according to the difference of pier position department geological conditions, it is to adopt different modes: dredging, namely excavating by adopting a gas lift reverse circulation mud suction method, and pumping the mud to a mud boat; the powder clay layer is excavated by adopting an excavator, meanwhile, the clay is loosened by matching with manpower, and then the excavated clay is transported outwards by adopting a grab bucket excavator;
in the water pumping and excavating process, each inner support 8 is lowered; the mounting sequence of the multi-layer inner support 8 follows the principle of first up and then down; the method comprises the following steps: when water is pumped to 1m below the designed elevation of the corresponding layer inner support 8, the corresponding layer inner support 8 is installed.
In an alternative embodiment of the invention, the cross section of the double-wall steel box cofferdam is square (e.g., square or rectangular); correspondingly, each inner support 8 has a diamond structure inscribed in the middle of each side wall of the double-wall steel sleeve cofferdam. When the cross section of the double-wall steel sleeve cofferdam is square, each inner support 8 is of a square structure. Specifically, the inner support 8 is installed at the position of the wall bin plate 9 of the double-wall steel cofferdam, so as to avoid the inner support 8 from damaging the side wall due to water pressure.
Example 1:
a double-wall steel sleeve cofferdam construction method comprises the following steps:
step S1, after pile foundation construction is completed, removing a drilling platform;
step S2, erecting a hole guiding platform 14, performing hole guiding construction, and replacing a rock-soil layer at a cofferdam design lowering position with sand;
step S3, the double-wall steel sleeve cofferdam is divided into three sections for assembly and lowering, and specifically comprises the following steps:
step S301, removing the hole guiding platform 14, and installing the assembly platform 13 on the steel casing 5.
The number of the steel casings 5 is 9, the 9 steel casings 5 are divided into three rows, and 3 steel casings 5 are uniformly distributed in each row and are distributed in a square shape. The steel casing 5 comprises 4 corner pile steel casings 51 and 4 edge steel casings 52 and 1 center steel casing, the corner pile steel casings 51 are located at the four corners, the edge steel casings 52 are located at the center of each edge of the square, and the center steel casing is located at the center of the square.
After the assembly platform 13 is installed, the four corner pile steel casings 51 are lengthened.
Step S302, assembling the first-section double-wall steel cofferdam 1 on an assembling platform 13, then installing a lifting system 7 at the top of a steel pile casing 5, installing a guide system 6 at the periphery of the steel pile casing 5, and guiding and matching the guide system 6 with the inner wall of the first-section double-wall steel cofferdam 1; the first-section double-wall steel cofferdam 1 is lifted by the lifting system 7, the part of the assembly platform 13 which is blocked from being lowered is removed, and then the first-section double-wall cofferdam is lowered by the lifting system 7.
The lifting system 7 comprises two vertically crossed lifting beams 73 fixedly arranged at the tops of the four corner pile steel pile casings 51, the end part of each lifting beam 73 is provided with a lifting point which is an upper lifting point 71, and each upper lifting point 71 is provided with a jack and a lifting rod 74 which are vertically arranged, and 8 jacks and 8 lifting rods (the lifting rods adopt prestress steel strands). The lower hanging points 72 are arranged on the inner side of the inner wall of the first double-wall steel cofferdam 1, and the positions of the lower hanging points correspond to the upper hanging points one by one. Specifically, an anchor bracket 75 is welded on the inner wall of the first double-wall steel cofferdam 1, and a hanging hole for inserting a hanging rod 74 is formed in the anchor bracket 75, and the position is a lower hanging point.
2 guide systems 6 are welded on the outer side of each corner pile steel pile casing 51, and 1 guide system 6 is connected on the outer side of each steel pile casing 52 in 4 sides, and the total number of the guide systems is 12.
In the lowering process, when the first double-wall cofferdam reaches self-floating after entering water, pouring wall cabin concrete into the wall cabin of the first double-wall cofferdam; stopping lowering when the top of the first section double-wall cofferdam is level with the splicing platform 13; after the first section double-wall cofferdam is lowered in place, the cofferdam is hung continuously by a hanging system 7; and after the wall cabin concrete reaches the design strength, separating the first section double-wall cofferdam from the hoisting system 7.
The accurate positioning measure of the first section double-wall steel cofferdam 1 is as follows:
in the descending process, scales are marked on the steel strands, and the verticality of the first section double-wall cofferdam is adjusted once when the steel strands are lowered for about 15cm, so that the descending process of the first section double-wall cofferdam is stable;
accurate positioning of the first section double-wall cofferdam after being lowered into place: the vertical position of the first double-wall cofferdam is accurately adjusted by controlling the water level in the wall bin of the first double-wall cofferdam; the plane position of the first-section double-wall cofferdam is accurately adjusted through the guide system 6.
Step S303, assembling a second section of double-wall steel cofferdam 2 on the top of the first section of double-wall steel cofferdam 1; after the assembly is completed, integrally lowering the two sections of double-wall steel cofferdam by adopting a lifting system 7; in the process of lowering, when the first section double-wall steel cofferdam 1 is inserted into sand to sink for a certain depth and then stops sinking, sand sucking operation is carried out at the bottom of a river bed, and the lifting system 7 is synchronously loosened and the lowering is continued; stopping lowering when the top of the second section double-wall steel cofferdam 2 is level with the assembly platform 13;
assembling a third section of double-wall steel cofferdam 3 on the top of the second section of double-wall steel cofferdam 2 to complete the integral assembling of the double-wall steel sleeve cofferdam; then, integrally lowering the double-wall steel sleeve cofferdam by adopting a lifting system 7; in the lowering process, sand sucking operation is carried out at the bottom of the riverbed, the lifting system 7 is synchronously loosened, and the double-wall steel sleeve cofferdam is continuously lowered under the action of the counter weight; when the top of the double-wall steel sleeve cofferdam is level with the splicing platform 13, the double-wall steel sleeve cofferdam stops being lowered.
In addition, each section of double-wall steel cofferdam is of a square structure consisting of 8 side plates A11 and 4 side plates B12, wherein the corner is the side plate B. The assembly process of each section of double-wall steel cofferdam is as follows: two corners at the diagonal positions of the square are taken as two splicing starting points, two paths of splicing are split, and the two paths of splicing are in a clockwise or anticlockwise splicing sequence.
When the first section double-wall cofferdam is lowered, the height of wall-cabin concrete poured into the cofferdam is 2.06m; when the second section of double-wall cofferdam is lowered, the height of wall-cabin concrete poured into the cofferdam is 2.45m; when the third section of cofferdam is lowered, the height of wall-cabin concrete poured into the cofferdam is 2.55m. Thus, the poured wall silo concrete height from the bottom of the cofferdam totals 8.79m.
And S304, assembling a single-wall steel cofferdam 4 at the top of the double-wall steel sleeve cofferdam.
S4, pumping and excavating operation is carried out, and a plurality of layers of inner supports 8 are arranged in the cofferdam;
and S5, pouring back cover concrete, wherein the back cover concrete is constructed by adopting a vertical conduit multipoint underwater pouring method. The pouring of the back cover concrete is carried out in a mode of gradually advancing from two sides to the center.
It is to be understood that the above description is exemplary only and that the embodiments of the present application are not limited thereto.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the particular embodiments disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Claims (8)
1. The construction method of the double-wall steel sleeve cofferdam is characterized by comprising the following steps of:
step S1, after pile foundation construction is completed, removing a drilling platform;
step S2, erecting a hole guiding platform, performing hole guiding construction around the hole guiding platform by adopting a rotary digging machine so as to form a ring groove matched with the bottom of the cofferdam on a riverbed, wherein the depth of the hole guiding is not higher than the elevation position of the design bottom of the cofferdam, backfilling sand after hole guiding is completed, and backfilling the sand to the elevation of the riverbed so as to replace a rock-soil layer at the position where the cofferdam is designed to be lowered with sand;
step S3, splicing and lowering the double-wall steel sleeve cofferdam sections in sequence;
s4, pumping and excavating operation is carried out, and a plurality of layers of internal supports are arranged in the cofferdam;
s5, pouring back cover concrete;
in the step S2, the annular groove is formed by connecting a plurality of holes, adjacent holes are meshed with each other, and the meshing width is not smaller than the wall thickness of the cofferdam;
in the step S2, the hole-by-hole construction is sequentially carried out, and the specific construction steps of the single hole are as follows:
step S201, firstly, punching a pilot hole casing;
step S202, performing drilling operation in the hole guiding pile casing;
step S203, a crescent protection barrel is put down in the hole guiding protection barrel;
step S204, sand is backfilled into the crescent protective cylinder;
step S205, pulling out the hole guiding pile casing; the crescent protective cylinder is reserved, so that the concave side of the crescent protective cylinder is used as a guide for installing the hole guiding protective cylinder when the corresponding next adjacent hole site is constructed;
in the whole hole guiding construction process in the step S2, each bearing platform uses two crescent protection cylinders and one hole guiding protection cylinder in a common cycle mode;
after the hole guiding construction of the next adjacent hole site is completed, the crescent protection barrel corresponding to the previous hole site is pulled out;
the concrete construction method of the hole guiding construction comprises the following steps:
hole guiding construction of the 1 st hole site is carried out: taking the concave side of the crescent protection cylinder corresponding to the 1 st hole site as the guide of the 2 nd hole site installation guide hole protection cylinder;
performing hole guiding construction of the 2 nd hole;
repeating the steps, and sequentially carrying out the subsequent construction of each hole site until the hole guiding construction of all the hole sites is completed.
2. A double-wall steel box cofferdam construction method as set forth in claim 1, wherein, before step S201, a horizontally disposed guide frame is installed for guiding said hole guiding casing to prevent said hole guiding casing from being deviated.
3. The double-wall steel casing cofferdam construction method as set forth in claim 1, wherein step S202, different drill-bit footage speeds are selected according to geological conditions during the drilling process.
4. The double-wall steel box cofferdam construction method as set forth in claim 1, wherein the step S3 specifically includes the steps of:
step S301, removing the hole guiding platform, and installing an assembly platform on the steel casing;
s302, splicing a first-section double-wall steel cofferdam on the splicing platform, installing a lifting system at the top of the steel pile casing, and installing a guide system at the periphery of the steel pile casing, wherein the guide system is in guide fit with the inner wall of the first-section double-wall steel cofferdam; the first-section double-wall steel cofferdam is lifted through the lifting system, a part of the assembly platform, which is blocked from being lowered, is removed, and then the first-section double-wall steel cofferdam is lowered by the lifting system;
and step S303, assembling and lowering the subsequent double-wall steel cofferdams.
5. The double-wall steel box cofferdam construction method of claim 4, wherein in step S303: and in the lowering process of each section of double-wall steel cofferdam, the whole double-wall steel cofferdam is lowered by adopting the lifting system, and the double-wall steel cofferdam is lowered in an auxiliary manner by carrying out sand sucking operation at the bottom of a river bed and increasing the dead weight of the cofferdam.
6. The double-wall steel box cofferdam construction method as set forth in claim 1, wherein in step S4, the concrete method of the water pumping excavation operation is as follows: firstly, temporarily fixing the top of the double-wall steel sleeve cofferdam and a steel casing, then pumping out water in the double-wall steel sleeve cofferdam by adopting a water pump, and then sucking mud for excavation;
in the suction dredge excavation process, according to the difference of the geological conditions of pier position department, it is to adopt different modes: dredging, namely excavating by adopting a gas lift reverse circulation mud suction method, and pumping the mud to a mud boat; the powder clay layer is excavated by adopting an excavator, meanwhile, the clay is loosened by matching with manpower, and then the excavated clay is transported outwards by adopting a grab bucket excavator;
and in the water pumping and excavating process, each layer of the inner support is lowered.
7. A double-wall steel box cofferdam construction method as in claim 6, wherein the installation sequence of multiple layers of said internal supports follows the principle of top-to-bottom.
8. The double-wall steel box cofferdam construction method of claim 7, wherein the cross section of the double-wall steel box cofferdam is square;
each layer of inner support is of a diamond structure inscribed in the middle of each side wall of the double-wall steel sleeve cofferdam.
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| CN115233714A (en) * | 2022-08-31 | 2022-10-25 | 中交一公局集团有限公司 | Continuous hole leading and slotting construction method for deep-water bare rock geological cofferdam |
| CN115419089A (en) * | 2022-09-01 | 2022-12-02 | 中铁七局集团武汉工程有限公司 | Shallow water bedrock geological bearing platform foundation pit construction method |
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