Without bottom concrete combined type cofferdam under the conditions of formation geology
The utility model is related to bridge deepwater foundation construction technology, more particularly, under the conditions of a kind of formation geology without back cover
The box-like cofferdam of coagulation local soil type.
In deep-water bridge foundation work progress, when run into close on have existing building basic when, be increase peace as far as possible
Full distance, it is ensured that the safety of existing building, has stronger stress performance and obvious size advantage using steel pipe pile cofferdam.
During normal steel-pipe pile cofferdam construction, its technological process is：Designed according to steel pipe pile cofferdam, carry out steel-pipe pile, fore shaft processing and spell
Dress；Sinking steel-pipe pile（Leading truck is installed on operation platform periphery, the gradient of steel-pipe pile is controlled, by theoretical chi on leading truck
Very little unwrapping wire makes the position of each steel-pipe pile, is impacted in place with vibro-pile driver）；Underwater pouring bottom concrete；Water is installed
Flat support；Pour into a mould concrete bearing platform and part pier shaft；Finally steel-pipe pile is pulled out again.But when the deeper rock stratum of excavation of foundation pit depth
When geological conditions is regional, because rock stratum hardness is larger, steel pipe pile cofferdam inserting piling is difficult, and root, which is difficult to squeeze into scar, takes root, and causes
Cofferdam structure system unstability, it is impossible to meet its force request.
The content of the invention
The purpose of this utility model is to provide under the conditions of a kind of formation geology without bottom concrete combined type cofferdam, can be with
Solve steel-pipe pile to be difficult to squeeze into scar anchoring, it is impossible to the problem of meeting cofferdam structure system force request.
To achieve the above object, the utility model can take following technical proposals：
Put under the conditions of formation geology described in the utility model without bottom concrete combined type cofferdam, including ring in cushion cap four
Closing fore shaft is provided between the rectangular steel pipe row of piles that week is made up of many steel-pipe piles, adjacent two steel-pipe pile；The steel-pipe pile
Lower base opening inserting piling has reinforced concrete drill to the strong-weathered rock layer surface of the cushion cap bottom in the lower end linking of the steel-pipe pile
Hole stake, the upper end of the reinforced concrete drilling stake is deeply to the steel-pipe pile inner chamber, and its lower end is through strongly weathered sand-rock and prolongs
Extend in weak weathered stratum.
The reinforced concrete drilling stake height deeply entered in the steel-pipe pile inner chamber >=2 meters.
Depth >=1 meter that the reinforced concrete drilling stake lower end is injected in weak weathered stratum.
Frame-type support system is provided with the closing space that steel pipe row of piles is surrounded above the cushion cap.
Described frame-type support system includes spaced horizontal from top to bottom and is welded on the steel pipe row of piles madial wall
At least two layers of support board and the rectangle collar tie beam being horizontally fixed in every layer of supporting plate, set in the middle part level of the rectangle collar tie beam
It is equipped between transverse support bar, the transverse support bar of upper and lower layer collar tie beam and is provided with longitudinally connected bar；The four of the rectangle collar tie beam
Angular position is respectively arranged with bearing diagonal.
The utility model has the advantage of simple in construction, easy construction, the rigidity and stability in overall cofferdam can meet peace
The technical requirements constructed entirely.The specific strata structure run into according to bridge deepwater excavation of foundation pit, by fore shaft steel-pipe pile inserting piling to holding
The strong-weathered rock layer surface of platform bottom, then does casing using steel-pipe pile, in the extension construction reinforced bar concrete drill hole stake of its lower end,
And pass through strongly weathered sand-rock to extend into the anchor foundation in the weak weathered stratum of lower section as cofferdam reinforced concrete drilling stake,
Cofferdam overall rigidity and stability are greatly improved, the technical requirements of safe construction are met；Simultaneously because weak-weathered rock
High density and high intensity that layer has, significantly reduce the infiltration phenomenon of cofferdam bottom, without being sealed again using concrete
Bottom, simplifies construction technology.
Brief description of the drawings
Fig. 1 is structural representation of the present utility model.
Fig. 2 is Fig. 1 top view.
The utility model is described in more details below in conjunction with the accompanying drawings.
As shown in Figure 1, 2, put under the conditions of formation geology of the present utility model without bottom concrete combined type cofferdam, including ring
Closing fore shaft is provided between the rectangular steel pipe row of piles being made up of in the surrounding of cushion cap 1 many steel-pipe piles 2, adjacent two steel-pipe pile 2；When
When there is weathered rock formation below foundation ditch, for convenience of constructing, by the strong-weathered rock of the lower base opening inserting piling of steel-pipe pile 2 to the bottom of cushion cap 1
3 surface of layer（The base opening of steel-pipe pile 2 should be more than 0.5 meter less than 1 elevation of bottom of cushion cap）, have reinforcing bar in the lower end linking of steel-pipe pile 2
Concrete drill hole stake 4, to ensure the rigidity and stability of cofferdam entirety, the upper end of reinforced concrete drilling stake 4 is deeply to steel pipe
Height in 2 inner chambers of stake is not less than 2 meters, and its lower end is extended in weak weathered stratum 5 after passing through strongly weathered sand-rock 3, to ensure anchor
Gu stable, the height for the reinforced concrete drilling stake deeply entered in weak weathered stratum 5 is not less than 1 meter；In the top of cushion cap 1 by steel pipe
Frame-type support system is provided with the closing space that row of piles is surrounded：The frame-type support system that the utility model is used is included certainly
Three layers of supporting plate 6 and be horizontally fixed in every layer of supporting plate 6 that upper and lower spaced horizontal is welded on steel pipe row of piles madial wall
Rectangle collar tie beam 7, have a transverse support bar 8 the middle part of rectangle collar tie beam 7 is horizontally disposed, the transverse support bar 8 of upper and lower layer collar tie beam it
Between be provided with longitudinally connected bar 9；Bearing diagonal 10 is respectively arranged with the corner location of rectangle collar tie beam 7.
During cofferdam construction of the present utility model, first by steel-pipe pile 2 by root from the inserting piling of riverbed face 11 to the bottom surface of coating 12
At position, after surrounding is closed up, it is allowed to penetrate strongly weathered sand-rock 3 to weak in every steel-pipe pile internal drilling successively using rotary drilling rig
Certain depth in weathered rock formation 5, then construction reinforced bar concrete drill hole stake 4（Descending reinforcing cage simultaneously pours into a mould concrete）, it is fully completed
Afterwards, that is, the combined type cofferdam that top is steel-pipe pile 2, bottom is reinforced concrete drilling stake 4 is formed.