CN102363961B - Deepwater single-wall steel plate pile cofferdam structure with low buried depth and construction method thereof - Google Patents
Deepwater single-wall steel plate pile cofferdam structure with low buried depth and construction method thereof Download PDFInfo
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Abstract
The invention discloses a deepwater single-wall steel plate pile cofferdam structure with low buried depth. The structure comprises a plurality of bored piles, a steel plate pile cofferdam around the bored piles, bagged sand positioned outside the cofferdam and arranged on the surface of a river bed, and high-pressure rotary jet piles constructed in the cofferdam and outside the bored piles, wherein the plane size of the cofferdam is greater than that of a bearing platform to be constructed so as to reserve a construction space. By using the steel plate pile cofferdam, the deepwater low pile bearing platform and the underwater part of a pier of a bridge can be constructed with relatively low cost and minimum construction risk, and a double-wall steel cofferdam scheme with relatively high cost does not need to be adopted for construction, so that the turnover steel consumption of the cofferdam serving as a temporary project is saved, and the application range of the deepwater steel plate pile cofferdam construction technology is enlarged.
Description
Technical field
The present invention relates to building foundation technical field of construction in underground and water, be specifically related to the technical field of steel sheet pile cofferdam structure and construction method thereof.
Background technology
In water, generally need to build coffering during foundation construction, to carry out dewatering excavation foundation ditch and foundation construction.So-called cofferdam, builds and goes along with sb. to guard him together building in foundation ditch surrounding exactly, and water is separated, to carry out excavation pit going along with sb. to guard him in building, forms dry execution conditions and carries out foundation construction.Also can say that cofferdam is while building in underground and water building, the provisional space enclosing structure of doing, its effect is to prevent that water and soil from entering the position of building of building, so that at space enclosing structure internal drainage, excavation base is anti-, builds building.Except design code is as permanent safeguard structure, generally, after pier body repairs the water surface, when pit backfill is complete, give dismounting, unimpeded with obstruction free current, the local scour in aggravation riverbed.
Steel sheet-pile cofferdam is that in bridge deepwater foundation construction, widely used one is gone along with sb. to guard him form temporarily, is also the most frequently used a kind of sheet pile cofferdam.Steel sheet-pile cofferdam compared with Double-Wall Steel Boxed Cofferdam, steel jacket box etc., have simple in structure, inserted to play ratio is easier to, short construction period, reusable, cost is lower and be easy to the advantages such as quality control, in the welcome of deepwater foundation construction Zhong Shou unit in charge of construction.
Steel sheet pile is applicable to sandy soil, half dry cohesive soil, rubble class soil waits soil layer, and can squeeze into weathered rock, during general employing steel sheet-pile cofferdam, require steel sheet pile to imbed the embedded depth of the soil body (being the pile top of steel sheet pile after the excavation of foundation pit degree of depth below foundation ditch bottom surface) and must reach minimum embedded depth requirement, to meet the self structure safety of steel sheet-pile cofferdam in excavation of foundation pit and foundation construction process, not there is not " skirt " and Piping phenomenon, the antiskid that meets cofferdam moves, overturning or slip resistance analysis, anti-protuberance at the bottom of anti-floating and foundation ditch, resist and gush the requirement of sand equistability.
In a lot of situations, even if the minimum embedded depth of steel sheet pile meets the demands, soil layer below foundation ditch bottom surface is compared with highly permeable soil layer or impervious layer thickness when little, need to take underwater excavation method, first excavate the following certain thickness soil layer in foundation ditch bottom surface, pour into again the bottom concrete under water of same thickness, to meet anti-protuberance at the bottom of cofferdam anti-floating and foundation ditch, anti-ly to gush the requirements such as sand.
Soil layer below foundation ditch bottom surface during for weak soil layer, requires steel sheet pile must have very large embedded depth, just can guarantee the stable of steel sheet pile cofferdam structure.Even like this, the internal force of steel sheet pile cofferdam structure, distortion still very large, usually can not meet the requirement of surrounding environment.Also need weak soil layer to change and fill out certain thickness, just can carry out the construction of bridge low pile cap simultaneously.If because rock stratum buried depth is more shallow or foundation ditch bottom surface is below the restriction of the conditions such as geologic(al) factor, place such as closely knit large erratic boulder, cause the embedded depth of steel sheet pile to suffer restraints and can not meet the demands, while not reaching the minimum constructive height that carries out underwater concrete back cover yet, adopt steel sheet-pile cofferdam to carry out the very risky of deepwater foundation construction, generally can only change at present and adopt Double-Wall Steel Boxed Cofferdam to construct.Double-Wall Steel Boxed Cofferdam need to through special design, foundation ditch underwater demolition that processing and fabricating, cofferdam are carried out in suitable place and dredge boat dredge leveling, large ship transportation or transportation by driving Double-Wall Steel Boxed Cofferdam sections to on-the-spot, lay complicated anchorage system, crane barge waterborne and carry out the assembled construction sequence more with connecing bottom concrete under height, water filling sinking, implantation location, clearly base priming petock etc., Double-Wall Steel Boxed Cofferdam be could form, then bored pile and the cushion cap foundation construction of bridge carried out.
Although Double-Wall Steel Boxed Cofferdam can bear larger hydraulic pressure, guarantee that basic annual construction safety crosses flood, but the material usage of Double-Wall Steel Boxed Cofferdam is large, recovery utilization rate is little, construction sequence and ship machine waterborne are many, the security risk of over-water construction is many, cost exceeds more compared with steel sheet-pile cofferdam, in addition owing to forming the long construction period of Double-Wall Steel Boxed Cofferdam, often make bridge deepwater bored pile lose the construction machine meeting in dry season of golden season and have to construct in the flood season in river, strengthen over-water construction risk, even can be because the arrival of flood is stopped work, incured loss through delay the duration of engineering.Particularly, when adopting steel sheet-pile cofferdam, former constructure scheme carries out the construction of bridge deepwater low pile cap, but after Bridge Bored Pile construction, during inserted to play steel sheet pile, find to fail the actual geological condition of true reflection due to geological mapping data, rock stratum buried depth shoals, scar absolute altitude fluctuations is large, cause the embedded depth of steel sheet pile can not meet the designing requirement of scheme, while changing into again double-wall steel cofferdam construction scheme, now the difficulty of construction of Double-Wall Steel Boxed Cofferdam and cost will be than determining that at the very start employing Double-Wall Steel Boxed Cofferdam scheme is much bigger, even may have influence on the quality of the bored pile of pile itself.
Therefore, need to research and develop a kind of steel sheet pile cofferdam structure, when the embedded depth of steel sheet pile suffers restraints and can not meet the demands, can carry out the construction of bridge deepwater low pile cap, and needn't change into, adopt the higher Double-Wall Steel Boxed Cofferdam scheme of cost to construct, save the turnover rolled steel dosage of cofferdam as temporary works, guarantee the quality and safety stability of steel sheet-pile cofferdam, assurance engineering is carried out construction bridges deep water low pile cap with lower cost and minimum construction risk, expands the range of application of deep water Construction Technique of Steel Sheet Cofferdam.
Summary of the invention
Object of the present invention is just being that the steel sheet pile embedded depth that solves cofferdam can not meet the technical barrier that normal embedded depth requires, and proposes a kind of new steel sheet pile cofferdam structure and construction method thereof.
Another object of the present invention is to provide a kind of applies above-mentioned construction method construction deep water single wall steel sheet pile cofferdam structure and carries out low pile cap and the method for bridge pier underwater portion construction.
In order to achieve the above object, the present invention is by the following technical solutions: the deep water single wall steel sheet pile cofferdam structure that a kind of embedded depth is little, is characterized in that comprising following structure:
Some bored piles, and
Be surrounded on the steel sheet-pile cofferdam outside bored pile, the planar dimension in cofferdam is greater than the cushion cap planar dimension of intending construction to reserve working space, and
Outside cofferdam, cast the packed sand in riverbed surface, and
Construct within cofferdam, the high-pressure rotary jet grouting pile outside bored pile.
The present invention carries out high-pressure rotary jet grouting pile slip casting processing by the foundation ditch bottom surface to steel sheet-pile cofferdam with the soil body in depth bounds between weathered rock, can significantly improve the mechanical performance indexes such as the cohesion, angle of internal friction of this scope soil body, also improve the passive earth pressure of this scope soil body, play and reduce the internal force of steel sheet pile cofferdam structure, the effect of horizontal movement, solve " skirt " problem of steel sheet pile bottom, in addition, this soil layer is through high pressure jet grouting processing, improved the air space ratio of specific density of solid particles and the reduction soil body, also just improved the critical hydraulic slope that " piping " occurs at the bottom of the foundation ditch of cofferdam, the more airtight entirety of the high pressure jet grouting soil body after treatment and the fixed formation of scar simultaneously, the cement paste of high-pressure rotary-spray is fixed most sand grains, it is very limited that the quicksand passage that the left space of inhomogeneities that may exist can form is permeated in slip casting, the path that the fixed rear penetration that has cut off water of grouting in soil mass drives fine grained to move between soil body space, improved significantly the impermeability of this layer soil body, at the bottom of greatly reducing foundation ditch, gush sand, piping, the risk of protuberance, even if there is this risk, also the progressive formation time that makes risk develop into " piping " from " quicksand " significantly extends, can make the personnel before " piping " outburst, equipment is withdrawn and is taken emergency measures and leave time enough, thereby reduced the extent of injury of " piping " risk.In addition, 5m scope outside steel sheet-pile cofferdam is cast to packed sand and carry out river bottom protection, can strengthen cofferdam rigidity, reduce the impact of " swing " phenomenon that steel sheet pile cofferdam structure occurs under the water pressure changing, action of wave force, to ensure the general safety of foundation ditch.
When steel sheet pile elevation of bottom and default absolute altitude differ larger, outside cofferdam, correspondence position increases high-pressure rotary jet grouting pile, between the adjacent high-pressure rotary jet grouting pile of inner side, described cofferdam, mutually overlap 0.1m, between the adjacent high-pressure rotary jet grouting pile in outside, cofferdam, mutually overlap 0.15m, at the bottom of the Pile of High-pressure Spiral Jet of medial and lateral, arrive weathered rock or enter the following 0.1～0.2m of weathered rock, the Pile of High-pressure Spiral Jet top mark in outside, cofferdam is high higher than the Pile of High-pressure Spiral Jet top mark in cofferdam.Overlap joint between adjacent high-pressure rotary jet grouting pile is encrypted and can be played the effect of strengthening this position water proof reliability, the high high-pressure rotary jet grouting pile than inner side of Pile of High-pressure Spiral Jet top mark in its outside, cofferdam exceeds 3.0m, and stake end absolute altitude is identical with the high-pressure rotary jet grouting pile of steel sheet pile inner side.
Particularly, described steel sheet pile bottom arrives weathered rock or enters the following 0.1～0.2m of weathered rock.
Further, steel sheet pile cofferdam structure of the present invention also comprises some layers of horizontal struts system, and described horizontal struts system is for enclosing purlin and supporter.
A construction method for the deep water single wall steel sheet pile cofferdam structure that embedded depth is little, comprises the following steps:
(1) construction drill castinplace pile;
(2) inserted to play steel sheet pile, close up formation steel sheet-pile cofferdam;
(3) outside cofferdam, cast packed sand and carry out river bottom protection;
(4) carry out Construction of High Pressure Jet Grouting Pile;
(5) draw water, excavation pit, some layers of horizontal struts system are installed.
Particularly, described horizontal struts system has 3～5 layers.
Particularly, described step (5) is drawn water and is adopted the method for layered extraction in cofferdam, and every installation one deck horizontal struts system is taken out lower one deck water again; While drawing water, steel sheet pile fore shaft is leaked and is in fore shaft outside installation rubber fastening band sealing; Steel sheet pile inner side adopts cotton stuff up a crack to carry out leak stopping.
Preferably, described rubber fastening band consists of strong magnet and rubber seal tape, described rubber seal tape wherein one side there is fin, described strong magnet is placed in described fin inside, and described fin under use state towards steel sheet pile.
A construction method for low pile cap and bridge pier underwater portion, is characterized in that comprising the following steps:
(1) according to the construction sequence of said method, form cofferdam structure;
(2) cut off the residue steel casing of bored pile, abolish the unnecessary concrete of pile crown, in cofferdam, clear base leveling, lays bearing platform construction bed course;
(3) fabrication and installation cushion cap reinforcing bar, builds cushion cap first floor concrete, and Cast-in-situ Piles in Sand-filling, to first floor cushion cap face, is removed basecoat horizontal struts system;
(4) build cushion cap second layer concrete, Cast-in-situ Piles in Sand-filling, to cushion cap end face, is removed layer horizontal struts system second from the bottom;
(5) underwater portion of the pier shaft of segmented construction bridges, removes remaining horizontal struts system successively;
(6) pier construction surfaces after certain altitude, pulls out steel sheet pile.
The quality and safety stability of using steel plate pile cofferdam of the present invention accesses assurance, make engineering come construction bridges deep water low pile cap and bridge pier underwater portion with lower cost and minimum construction risk, and needn't adopt the Double-Wall Steel Boxed Cofferdam scheme that cost is higher to construct, save the turnover rolled steel dosage of cofferdam as temporary works, expanded the range of application of deep water Construction Technique of Steel Sheet Cofferdam.The integrated cost that adopts steel sheet-pile cofferdam to construct is low more than Double-Wall Steel Boxed Cofferdam scheme cost.
Accompanying drawing explanation
Fig. 1 a is the layout plan of steel sheet pile cofferdam structure of the present invention.
Fig. 1 b is the A-A sectional drawing of Fig. 1 a.
Fig. 1 c is the B-B sectional drawing of Fig. 1 a.
Fig. 2 is the schematic diagram that application steel sheet pile cofferdam structure of the present invention carries out low pile cap and the construction of bridge pier underwater portion, wherein
Fig. 2 a shows steel sheet pile inserted to play, has closed up, and outside, cofferdam casts packed sand river bottom protection;
Fig. 2 b shows that Construction of High Pressure Jet Grouting Pile completes;
First floor horizontal struts system is drawn water, installs in Fig. 2 c demonstration;
Second layer horizontal struts system is drawn water, installs in Fig. 2 d demonstration;
It is anti-that Fig. 2 e shows that base is drawn water, excavates in layering, and the 3rd and the 4th layer of horizontal struts system is installed;
Cushion cap first floor concrete has been built in Fig. 2 f demonstration;
Fig. 2 g shows Cast-in-situ Piles in Sand-filling to first floor cushion cap face and removes the 4th layer of horizontal struts system;
Cushion cap second layer concrete has been built in Fig. 2 h demonstration;
Fig. 2 i shows that Cast-in-situ Piles in Sand-filling is to cushion cap end face, and segmented construction completes the underwater portion of bridge pier shaft and removes remaining horizontal struts system;
Fig. 3 is the build process flow chart of steel sheet pile cofferdam construction bridge low pile cap and pier shaft underwater portion;
Fig. 4 a is rubber fastening band structural representation;
Fig. 4 b is that rubber fastening band is used view.
Wherein, 101 steel sheet pile 102 cushion cap 102a first floor cushion caps 103 enclose 402 outsides, cofferdam, steel casing 107 packed sand 108,109 high-pressure rotary jet grouting pile 110 bed course 111 Cast-in-situ Piles in Sand-filling 112 pier shaft 201 migmatitic granite scar 202 riverbed face 301 strong magnet 302 rubber seal tape 401 inner side, cofferdam of purlin 104 cross binding 105 angle brace 106 bored pile 106a bored piles
The specific embodiment
As shown in Fig. 1 a～1c, it is the schematic diagram of steel sheet pile cofferdam structure example of the present invention.
Xian Yimou city road bridge be constructed to example, this main spanning footpath is combined as the self-anchored suspension bridge of (80m+200m+80m).Main pier is 16 and No. 17 piers, is arranged in navigation channel, Huaihe River, and covering layer mainly consists of silt, clay, fine sand, gravelly sand, and overburden cover 5.5～11m changes very large.Subterrane is followed successively by completely decomposed hornblende, severely-weathered migmatitic granite, middle weathering hornblende, middle weathering migmatitic granite from top to bottom.
No. 16 pier scar absolute altitudes that former design drawing provides are-2.86m, No. 17 pier is-0.76m, because scar changes fluctuations very greatly, the bottom of finding steel sheet pile during test pile can reach far away design elevation at the bottom of the steel sheet pile of former steel sheet-pile cofferdam, No. 16 piers requirement steel sheet pile embedded depths are 5.93m, and it is 3.83m that No. 17 piers require steel sheet pile embedded depth.Re-start after geology is supplemented probing and find, mend and bore the larger difference that exists that result and former design drawing provide, mainly that No. 16 piers of actual scar absolute altitude are-0.2～0.3m, No. 17 piers are+1.3～+ 1.5m, mend to bore and find that main pier covering layer only has 5.8m～8.1m, the scar absolute altitude that actual scar provides than former design drawing exceeds 2.5m, and the most shallow scar absolute altitude in cofferdam is+1.5m that the most shallow embedded depth of steel sheet pile of No. 17 piers can only reach 1.57m.The actual injection process of steel sheet pile, even No. 16 piers also have can only arrive+1～+ 1.52m absolute altitude of the steel sheet pile of multiple positions.For solving this technical barrier, adopted steel sheet-pile cofferdam design scheme of the present invention to carry out the bearing platform construction of No. 16, No. 17 piers.
Overall construction process is as shown in Figure 3: site operation preparations → steel sheet pile inserted to play, close up form in cofferdam → high-pressure rotary jet grouting pile mortar depositing construction → cofferdam by predetermined absolute altitude successively draw water, excavate → horizontal struts system → foundation ditch bottom surfaces such as enclosing purlin and horizontal steel tube support is from top to bottom successively installed process and lay bed course → bearing platform construction → successively Cast-in-situ Piles in Sand-filling, successively remove the horizontal steel tube support in cofferdam and enclose the dismounting of purlin → pier shaft underwater portion construction → steel sheet pile.
Specifically, take following steps:
(1), according to construction condition and schedule requirement, main pier employing is first set up brill stake platform waterborne and is completed bored pile 106 foundation constructions.
(2) steel sheet pile inserted to play and closing up
The inserted to play of beginning steel sheet pile construction after following on-the-spot preparation completes: after 1. bored pile 106 has been constructed, rig is withdrawn to cofferdam construction scope; 2. accurately measure the position, sideline that setting-out goes out steel sheet-pile cofferdam; 3. to reinforcing sealing of hole processing as the steel casing position of the bored pile in hoisting operation district.The planar dimension in cofferdam outwards expands 1.5m by cushion cap 102 plane geometry sizes, to guarantee bearing platform construction working space.Cofferdam adopts the Lashen IV type steel sheet pile 101 of U-shaped, and yield strength is 295MPa.
Adopt the inserted to play equipment of 150kw electrodynamic type vibrating hammer as steel sheet pile, because it is meeting on the basis of the parameter requests such as exciting force, better to the control of steel sheet pile verticality, cost is also cheap.Adopt in addition 50t crawler crane lifting vibrating hammer to coordinate the inserted to play of steel sheet pile.
Steel sheet pile bottom arrives weathered rock or enters the following 0.1～0.2m of weathered rock.After steel sheet-pile cofferdam closes up, under diver coordinates by manually outside steel sheet-pile cofferdam 5m scope cast packed sand 107 and carry out river bottom protection.
(3) Construction of High Pressure Jet Grouting Pile
The construction of employing single pipe method, every meter of long strength grade 32.5 Portland cement 200kg and calcium chloride 4kg of mixing of stake, calcium chloride purity is greater than 70%.During Construction of High Pressure Jet Grouting Pile, in keyhole position deviation≤50mm, spray gradient≤1.0% of Grouting Pipe, the pressure that sprays Grouting Pipe is controlled at 20～30MPa, and the long churning cycle of every m stake is 7min.All Ranges construction high-pressure rotary jet grouting pile 108 in cofferdam, beyond bored pile position, stake top mark height for high-pressure rotary jet grouting pile 108 be cushion cap bottom surface absolute altitude, an end absolute altitude, to the scar of decomposed rock, generally can enter into 0.1～0.2m below weathered rock.For occurring that steel sheet pile elevation of bottom and default absolute altitude differ the situation of larger position, take correspondence position increase by 2 row's high-pressure rotary jet grouting piles 109 outside steel sheet pile to process.A stake footpath for inner side high-pressure rotary jet grouting pile 108 and outside high pressure rotary churning pile 109 is 0.50m, mutually overlaps 0.1m between the adjacent high-pressure rotary jet grouting pile in inner side, mutually overlaps 0.15m between the adjacent high-pressure rotary jet grouting pile in outside.
(4) in cofferdam, draw water, excavate and install and enclose purlin, horizontal steel tube Construction of Supporting
In the time of inserted to play steel sheet pile, carry out the processing of braced structures unit, cofferdam on the vacant lot on limit, cofferdam, after guaranteeing that steel sheet pile inserted to play completes, the braced structures in cofferdam can be installed as early as possible.
In cofferdam, drawing water and taking layered extraction method, layering principle is to take out lower one deck water after every installation one deck encloses purlin 103 and cross binding 104, angle brace 105 again.First floor draws water to be evacuated to lower than first floor and encloses the following 1.5m of purlin absolute altitude place, and welding bracket is installed first floor and enclosed purlin and horizontal steel tube cross binding.After installation, continuing draws water is evacuated to the second layer and encloses the following 1.5m of purlin absolute altitude place, the second layer is installed and is enclosed purlin and cross binding 104, angle brace 105.According to said method, complete drawing water in cofferdam.While drawing water, the steel sheet pile fore shaft place of leaking is installed to rubber fastening band by diver in fore shaft outside and carry out sealing, this kind of waterstop structure as shown in Fig. 4 a, adopt strong magnet 301 and rubber seal tape 302 to form, the wherein one side of rubber seal tape 302 has fin, in fin rib body, be provided with placement hole, described strong magnet is placed in described placement hole, and the one side that rubber seal tape has a fin under use state towards steel sheet pile, be attached to steel sheet pile fore shaft outside, run into outer lateral water pressure, can be more sticky tighter, it is installed and used as shown in Figure 4 b.Little leak inside steel sheet pile, can adopt cotton stuff up a crack to carry out leak stopping.
In cofferdam, soil excavation adopts the dry excavation method of layering, piecemeal, utilizes mini-excavator excavation and inhale mud excavation to combine.The principle of stage excavation is the lower one deck earthwork of excavation again after every construction one deck horizontal struts system, and the first floor soil excavation degree of depth is three layers of horizontal struts system bottom of riverbed face to the, installs the 3rd layer and encloses purlin and horizontal steel tube support; Then carry out second layer soil excavation, the 4th layer of horizontal struts system is installed, then carry out last one deck soil excavation.While adopting piecemeal excavation, exactly foundation ditch is divided into periphery piece and middle part piece, piecemeal excavation digs surrounding piece again for first digging middle part piece.
The inner support system in cofferdam forms by enclosing purlin 103, angle brace 105 and cross binding 104, is the main force structure in cofferdam.Enclose purlin and carry out unit piecemeal processing at back court, re-use flat car and be transported to job site and install.During installation, first on steel sheet pile, weld bracket, will enclose purlin 103 and install on bracket, welding is enclosed purlin 103 and is formed entirety.Enclose purlin and install, cross binding 104 and angle brace 105 are immediately installed.The for the benefit of stressed and sealing of steel sheet pile, adds channel-section steel between purlin 103 and steel sheet pile space and is connected enclosing.
(5) clear base, leveling and laying bed course in cofferdam
In cofferdam, arrange several collecting wells, adopt the draining of carrying out drawing water in cofferdam of high-power water pumper, then by the work of manually carrying out the excavation that bottom, cofferdam 0.2～0.3m is thick, clear base and leveling.
The concrete mats layer thickness of bearing platform construction is 0.469m, owing to there are some percolating waters in steel sheet pile fore shaft and inner side, water pressure in bottom surface, concrete cushion middle part can be greater than bed course gravity pressure, probably bad bed course is worn out on top, in order to solve the stability against floating problem of concrete cushion, take to lay several rubble seep-guiding channels in bed course, the hydraulic pressure at the bottom of playing loaded filter effect and reducing bed course, make bed course week back gauge steel sheet pile 0.05m, for bed course bottom water pressure provides release channel simultaneously.
(6) bearing platform construction
After bed course completes, carry out bearing platform construction, cushion cap is divided into two-layer building and forms, and thickness is 5m.During cushion cap concrete construction, carry out control and the monitoring of concrete temperature.
(7) pit backfill in cofferdam and cofferdam demolition
Cast-in-situ Piles in Sand-filling is to end face, the cushion cap end face of cushion cap gradation LIFT successively, and remove the horizontal steel tube support of corresponding level and enclose purlin, and the bottom of segmented construction bridges pier shaft is to surfacing after certain altitude, adopt 50t crawler crane to coordinate 150kw electrodynamic type vibrating hammer by eradicating except steel sheet pile, recover the original form in riverbed.
Through implementing the present invention, the steel sheet-pile cofferdam of engineering is in whole excavation of foundation pit and bridge bearing platform work progress, every stress of cofferdam structure and the pile body deformation monitored data of steel sheet pile are all within the safe range allowing, at the bottom of the foundation ditch in cofferdam, there is not protuberance and gush sand phenomenon, the a small amount of water burst occurring in digging process is through taking normal water-pumping/draining measure to be processed, and the bearing platform construction of bridge is able to the flood in Huaihe River on schedule and completes smoothly before arriving.The quality and safety stability of the steel sheet-pile cofferdam of the present invention's application accesses assurance, make engineering with lower cost and minimum construction risk, carry out the underwater portion of construction bridges deep water low pile cap and bridge pier, and needn't adopt the Double-Wall Steel Boxed Cofferdam scheme that cost is higher to construct, save the turnover rolled steel dosage of cofferdam as temporary works, expanded the range of application of deep water Construction Technique of Steel Sheet Cofferdam.Through Finance Department, adjust, the Double-Wall Steel Boxed Cofferdam scheme that two main pier bearing platforms of this engineering adopt while adopting integrated cost that steel sheet-pile cofferdams construct than bidding for project has been saved nearly 1,800,000 yuan.
As shown in detailed construction step schematic diagram figure as each in Fig. 2, wherein:
Fig. 2 a shows: after construction drill castinplace pile, carry out steel sheet pile inserted to play, close up.
Fig. 2 b shows: Construction of High Pressure Jet Grouting Pile completes.
Fig. 2 c shows: examination is drawn water, caulking joint sealing; First floor is installed and is enclosed purlin 103, cross binding 104 and angle brace 105.
Fig. 2 d shows: the following 1.5m of the center line position of the second layer horizontal struts system that draws water; The second layer is installed and is enclosed purlin 103 and cross binding 104, angle brace 105.
Fig. 2 e shows: in cofferdam, draw water, excavate, install the 3rd layer and enclose purlin 103 and cross binding 104, angle brace 105; In cofferdam, draw water, excavate, install the 4th layer and enclose purlin 103 and cross binding 104, angle brace 105.
Fig. 2 f shows: in cofferdam, draw water, excavate; Cut off the residue steel casing of bored pile, abolish the unnecessary concrete of pile crown; Clear base and leveling in cofferdam, the bed course of laying bearing platform construction; Fabrication and installation cushion cap reinforcing bar, builds cushion cap first floor concrete.
Fig. 2 g shows: Cast-in-situ Piles in Sand-filling is to first floor cushion cap face; Remove the 4th layer and enclose purlin 103 and cross binding 104, angle brace 105.
Fig. 2 h shows: built cushion cap second layer concrete.
Fig. 2 i shows: Cast-in-situ Piles in Sand-filling is to cushion cap end face; Remove the 3rd layer and enclose purlin 103 and cross binding 104, angle brace 105; The pier shaft underwater portion of segmented construction bridges, and remove successively second, one deck encloses purlin 103 and cross binding 104, angle brace 105; Pier construction surfaces after certain altitude, can pull out steel sheet pile.
Claims (8)
1. the deep water single wall steel sheet pile cofferdam structure that embedded depth is little, is characterized in that comprising following structure:
Some bored piles, and
Be surrounded on the steel sheet-pile cofferdam outside bored pile, the planar dimension in cofferdam is greater than the cushion cap planar dimension of intending construction to reserve working space, and steel sheet pile bottom arrives weathered rock or enters the following 0.1～0.2m of weathered rock, and
Construct within cofferdam, the high-pressure rotary jet grouting pile of All Ranges outside bored pile, and
Outside cofferdam, cast the packed sand in riverbed surface.
2. cofferdam structure according to claim 1, it is characterized in that: the high-pressure rotary jet grouting pile that also comprises outside, cofferdam, between the adjacent high-pressure rotary jet grouting pile of inner side, described cofferdam, mutually overlap 0.1m, between the adjacent high-pressure rotary jet grouting pile in outside, cofferdam, mutually overlap 0.15m, at the bottom of the Pile of High-pressure Spiral Jet of medial and lateral, arrive weathered rock or enter the following 0.1～0.2m of weathered rock, absolute altitude is identical, and the Pile of High-pressure Spiral Jet top mark in outside, cofferdam is high higher than the Pile of High-pressure Spiral Jet top mark in cofferdam.
3. cofferdam structure according to claim 1 and 2, is characterized in that: also comprise some layers of horizontal struts system, described horizontal struts system is for enclosing purlin and supporter.
4. a construction method for the deep water single wall steel sheet pile cofferdam structure that embedded depth as described in as arbitrary in claim 1～3 is little, is characterized in that comprising the following steps:
(1) construction drill castinplace pile;
(2) inserted to play steel sheet pile, close up formation steel sheet-pile cofferdam;
(3) outside cofferdam, cast packed sand and carry out river bottom protection;
(4) carry out Construction of High Pressure Jet Grouting Pile;
(5) draw water, excavation pit, some layers of horizontal struts system are installed.
5. method according to claim 4, is characterized in that: described horizontal struts system has 3～5 layers.
6. according to the method described in claim 4 or 5, it is characterized in that: described step (5) is drawn water and adopted the method for layered extraction in cofferdam, and every installation one deck horizontal struts system is taken out lower one deck water again; While drawing water, steel sheet pile fore shaft is leaked and is in fore shaft outside installation rubber fastening band sealing; Steel sheet pile inner side adopts cotton stuff up a crack to carry out leak stopping.
7. method according to claim 6, described rubber fastening band consists of strong magnet and rubber seal tape, the wherein one side of described rubber seal tape has fin, in fin rib body, be provided with placement hole, described strong magnet is placed in described placement hole, and described fin under use state towards steel sheet pile.
8. a construction method for low pile cap and bridge pier underwater portion, is characterized in that comprising the following steps:
(1) according to the construction sequence of claim 4～7 either method, form cofferdam structure;
(2) cut off the residue steel casing of bored pile, abolish the unnecessary concrete of pile crown, in cofferdam, clear base leveling, lays bearing platform construction bed course;
(3) fabrication and installation cushion cap reinforcing bar, builds cushion cap first floor concrete, and Cast-in-situ Piles in Sand-filling, to first floor cushion cap face, is removed basecoat horizontal struts system;
(4) build cushion cap second layer concrete, Cast-in-situ Piles in Sand-filling, to cushion cap end face, is removed layer horizontal struts system second from the bottom;
(5) underwater portion of the pier shaft of segmented construction bridges, removes remaining horizontal struts system successively;
(6) pier construction surfaces after certain altitude, pulls out steel sheet pile.
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| KR100645319B1 (en) * | 2005-08-16 | 2006-11-14 | (주) 선암기술연구소 | Pile foundation construction method using temporary cofferdam caisson of improved for weakness ground |
| JP4793634B2 (en) * | 2006-02-03 | 2011-10-12 | 清水建設株式会社 | Temporary deadline construction method |
| CN201068567Y (en) * | 2007-06-08 | 2008-06-04 | 上海朱翔建设工程有限公司 | Larssen steel sheet pile magnetic water stop strip |
| CN101368389B (en) * | 2008-09-24 | 2010-06-02 | 中铁大桥局集团第五工程有限公司 | Single and double-wall combined steel cofferdam construction method and its single and double-wall combined steel cofferdam |
| CN101538833B (en) * | 2009-04-10 | 2011-06-08 | 中交一航局第二工程有限公司 | Vertical subsection double-wall steel cofferdam water stopping construction method |
| CN202401462U (en) * | 2011-11-11 | 2012-08-29 | 中交四航局第一工程有限公司 | Deep-water single-wall steel sheet pile cofferdam structure with small soil penetration depth |
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