CN101560773A - Water-retaining cofferdam mode used in case of difficult implementation of heavy excavation method - Google Patents

Abstract

The invention relates to a water-retaining cofferdam mode in water and electricity construction. The water-retaining cofferdam comprises post-poured concrete and open caisson group, wherein, reserved clearances are arranged among open caissons, the bottoms of open caissons are covered and opening locking piles are arranged among open caissons. The invention has reasonable design and reliable structure, completely combines excavation support with cofferdam structure, not only saves investment but also meets the requirement of construction progress, and is a better covering layer-treating mode and a cofferdam mode when the heavy excavation scheme is unfeasible.

Description

Water-retaining cofferdam when the heavy excavation method is difficult to carry out

Technical field

The present invention relates to the water-retaining cofferdam built in a kind of construction of hydropower facilities.

Background technology

Under the prior art condition, the concrete longitudinal cofferdam of general stage diversion all ties up in the foundation ditch carries out heavy excavation to bedrock surface after-pouring concrete to the weir base.Under the conditions such as, covering layer better at geological conditions approaches, the water conservancy diversion flow is little, the riverbed width is broad relatively is feasible, but covering under the conditions such as bed thickness, the water conservancy diversion flow is big, the riverbed width is narrow relatively, the concrete longitudinal cofferdam height is often bigger, the restriction that arranged by water conservancy diversion retaining, outlet structure escape works and water conservancy project hinge, to in foundation ditch, dig out very difficulty of concrete longitudinal cofferdam weir base, therefore, it is very important selecting rational cofferdam and covering layer to handle pattern, otherwise, do not reach the programming requirement, generate electricity for engineering on time and stay hidden danger.

Also disclose many various construction technologies relevant in the prior art, comprised sinking open caisson, back cover, locking notch pile, bonding surface cutter Mao Bingshe link bar etc. with the construction of hydropower stations.Referring to " Hydraulic and Hydro-Power Engineering construction handbook China Electric Power Publishing House, " reinforced concrete structure structure handbook metallurgical industry publishing house.

In the prior art, the sinking open caisson mainly applies to underground structure (as underground gas-holder, oil storage tank, underground warehouse, underground conservation pool, water treating pond, underground pump house, the underground parking, the subway station, underground shelter, the underground store, underground substation etc.), the building structure base is (as Tall Building Foundation, towering Tower Building basis, the urban elevated road basis, steel mill's blast furnace foundation, the jumbo basis, different types of rridges, port and pier, structure base in the water such as dam) and (document that sees reference " the open caisson caisson construction technology " People's Transportation Press) such as well formula structure on the middle of the river and bank.But during these were used, open caisson all was as independently individual use.

General open caisson all needs back cover, when being used for the longitudinal cofferdam of water power hydraulic engineering, it is tighter that the open caisson ground is handled general requirements, must guarantee stable, reliable, bearing the bigger open caisson of lateral force should be located on the rock foundation, and take dowel and steel concrete back cover (referring to China Electric Power Publishing House " Hydraulic and Hydro-Power Engineering construction handbook P562); When excessive or foundation stability can not satisfy requiring of building when the shallow foundation settling amount on the natural ground, often adopt stake to do basis (referring to " ground and basis " P453 of China Construction Industry Press).Be mainly used in the basis of sluice, aqueduct, electric power pylon, transformer station, flood protection wall, service bridge etc. at the Hydraulic and Hydro-Power Engineering king-pile, also often be applied in the engineerings such as erosion control, retaining soil, antiskid (referring to China Electric Power Publishing House " the Hydraulic and Hydro-Power Engineering handbook P431 that constructs).

Summary of the invention

The technical problem to be solved in the present invention is, at covering big, the concrete cofferdam when heavy excavation method is difficult to carry out of bed thickness, cofferdam height, provides that a kind of technical scheme is feasible, reliable in structure and can satisfy the covering layer that construction speed requires and handle and weir build formula.

Water-retaining cofferdam provided by the invention comprises back pouring concrete and open caisson group, needs preset clearance between the open caisson, and open caisson carries out back cover, and establishes locking notch pile between open caisson and open caisson.

For the biography of strengthening back pouring concrete and open caisson group is cut ability and the safety and stability that ensures association, open caisson and back pouring concrete bonding surface are cut a hole the hair processing, and add link bar.

Solution is: consider that the open caisson group sinks to allowing the gradient requirement, need preset clearance between open caisson and the open caisson, (open caisson and back pouring concrete association) has the antiseepage requirement because the cofferdam, and the intractability of anti-seepage effect that will reach high cofferdam between well in the preset clearance between back pouring concrete and the open caisson outside wall surface is very big; Simultaneously in order to reduce the physical dimension in high cofferdam, the side that need meet water in the cofferdam is provided with basic curtain grouting and collector drain to reduce the foundation bottom uplift pressure, so with comparatively suitable cofferdam land side position sinking open caisson group.According to cofferdam water retaining Stability Analysis of Structures and stress requirement, in conjunction with the influence basin analysis results of well sinking to the surrounding buildings thing, determine open caisson group's plan-position, treat that well sinking puts in place and finishes the construction of carrying out the native locking notch pile of retaining between open caisson and open caisson behind the back cover, locking notch pile construction finishes and promptly remains excavation between weir body weir base and well, simultaneously open caisson and back pouring concrete bonding surface are cut a hole the construction that hair and link bar spreading etc. are handled, build open caisson section weir body concrete in addition then.

Open caisson at first is as independently individual among the present invention---interim retaining wall, and go along with sb. to guard him also to need after down weir, cofferdam base being excavated to foundation plane form at retaining wall and wholely come dash as a kind of composite type batardeau with the back pouring concrete.Locking notch pile among the present invention is a kind of soil blocking pile, and main consideration with covering layer between the excavation well, reaches right output port sealing between open caisson and the open caisson cofferdam and builds basic requirement; Bonding surface cutter Mao Bingshe link bar is the common structure treatment measure of New-old concrete joint surface, but general processing area is little, and the present invention is used for large tracts of land (open caisson group left surface) and power transmission requirement height.

Though the following heavy well of above-mentioned these forms of construction work, back cover, locking notch pile, bonding surface cutter Mao Bingshe link bar etc., single is method well known in the prior art, is initiative but these single technologies can be combined to one, apply in the water-retaining cofferdam in the hydroelectric project industry.

The invention has the beneficial effects as follows, by adopting the open caisson group can successfully solve the difficulty that base excavation place, weir is arranged, the gang of wells end is carried out need because of sinking between open caisson and open caisson can guaranteeing behind the fore shaft cleaning of preset clearance inner covering layer, simultaneously because the construction of back pouring concrete and open caisson has priority, back pouring concrete and open caisson bonding surface will be weak structural planes, by open caisson and concrete joint surface are cut a hole hair, and add the biography that can improve bonding surface behind the link bar and cut ability, guarantee the safety and stability of association.This invention is reasonable in design, reliable in structure, excavation supporting combines with the weir body structure is complete, not only reduces investment outlay but also can satisfy the construction speed requirement, be the heavy excavation scheme when being difficult to carry out a kind of covering layer preferably handle and weir build formula.

Description of drawings

Fig. 1 is that cofferdam concerns drawing in side sectional elevation with excavation;

Fig. 2 is adjacent open caisson dislocation fore shaft arrangement diagram between well when arranging;

Fore shaft arrangement diagram between well when Fig. 3 is the neat position of adjacent open caisson layout;

Fig. 4 is the link bar arrangement diagram of open caisson and weir body concrete.

Wherein: 1---lst stage earth rockfill cofferdam; 2---the original place upper thread; 3---basement rock and Quaternary system line of demarcation; 4---little weathered zone lower limit; 4---first phase excavation of foundation pit line when not making open caisson; 5---second phase vertical weir, weir base excavation line when making open caisson; 6---open caisson; 7---pouring concrete behind the body of weir; 8---pouring concrete bonding surface behind open caisson and the weir body; 9---link bar; The right side bearing in 10 phase water conservancy diversion bottom outlet forward positions (two vertical elevation 260m are with the limes superiors left side bearing); 11---the channel of approach base plate; 12---locking notch pile; 13---fill concrete between well.

The specific embodiment

Certain large hydropower station project scale is huge; dam site engineering geological conditions complexity; the river valley relative narrower; adopt stage diversion and water conservancy diversion flow big; its the second stage of longitudinal cofferdam dam Upstream section ground covering and deep reaches 45m～62m; if do not add any supporting measure; directly under the lst stage earth rockfill cofferdam protection, excavate second phase vertical weir, weir base covering layer (being the heavy excavation method); when lst stage earth rockfill cofferdam is put the slope to the bedrock surface elevation from weir crest; about 90m～the 120m of horizontal width of first phase foundation ditch side slope; the second stage of position of indulging the weir fully accounts on the plane; and exceeded the right side bearing (see figure 1) in the water conservancy diversion bottom outlet forward position that is used for the second stage of earial drainage; therefore, must take supporting measure just can reach in the first phase foundation ditch second phase vertical weir ground covering layer is all excavated the purpose of building the weir body concrete then.Through multivariant research with than choosing, its supporting measure adopts technical scheme of the present invention, at the heavy gang of wells in underfooting, weir, first phase cofferdam, early stage, the interim retaining wall as weir base and dam foundation dredging (utilized weir, open caisson retaining soil excavation left side base to bedrock surface, build left weir body concrete then), later stage is as the part associating dash of gravity cofferdam structure, maximum height of weir 94m.The open caisson group is made up of the open caisson of 10 17m * 23m, designs maximum submergence depth 60m, minimum submergence depth 43m, spacing 2～2.2m between the open caisson well.After adopting open caisson group and back pouring concrete association as longitudinal cofferdam, solved successfully that this engineering covers bed thickness, height of weir is big, the foundation ditch area is narrow and small relatively, the heavy excavation method is difficult to carry out the second stage of longitudinal cofferdam is arranged and the build problem, guaranteed the safe operation in first phase cofferdam, the engineering construction schedule objective also realizes on time.

Claims (3)

1. Water-retaining cofferdam when 1, the heavy excavation method is difficult to carry out is characterized in that comprising back pouring concrete and open caisson group, needs preset clearance between the open caisson, and open caisson carries out back cover, and establishes locking notch pile between open caisson and open caisson.
2. 2, water-retaining cofferdam according to claim 1, it is that neat position is arranged it is characterized in that between the open caisson or dislocation is arranged.
3. 3, water-retaining cofferdam according to claim 1 and 2 is characterized in that open caisson is the open caisson of 17m * 23m, designs maximum submergence depth 60m, minimum submergence depth 43m, spacing 2～2.2m between the open caisson well when maximum height of weir 94m.

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