CN209760248U - Composite type underwater bearing platform foundation pit support structure - Google Patents

Abstract

The utility model discloses a compound aquatic cushion cap foundation ditch retaining structure belongs to bridge foundation construction technical field, including the inner wall vertically island cofferdam of building, the inner wall cross section of building the island cofferdam is the rectangle, the inner wall of building the island cofferdam is equipped with one row of drilling secant pile, the well lower part of drilling secant pile is equipped with the back cover concrete that is used for bearing the cushion cap. A row of drilling secant piles are drilled on the inner wall of the island-building cofferdam, so that the row of piles are integrally stressed, the bending resistance is high, and a good waterproof effect is achieved. Adopt the utility model discloses can satisfy bridge cushion cap construction and go on under anhydrous or stagnant water condition, the work progress does not have mud, the noise is low, civilized construction, environmental protection are effectual, has reduced the processing difficulty, and drilling secant pile construction need not a large amount of ship machine equipment, has solved with big costs, the period of construction is long, retrieve the technical problem of difficulty.

Description

Composite type underwater bearing platform foundation pit support structure

Technical Field

The utility model belongs to the technical field of bridge foundation construction, especially, relate to a compound subaqueous cushion cap foundation ditch retaining structure.

Background

Most of bridge abutment foundations are located below the ground surface water level, sometimes, water flow is large, and bridge bearing platform construction needs to be carried out under the condition of no water or static water. The cofferdam is an indispensable temporary water retaining structure for bridge underwater foundation construction, and can be divided into an earth rock cofferdam, a concrete cofferdam and a steel cofferdam according to different cofferdam construction materials. And in the deep water environment, the foundation construction in water is mostly carried out by adopting a double-wall steel cofferdam. However, the conventional double-wall cofferdam lowering operation needs underwater blasting of bedrock, the cofferdam processing difficulty is high, a large amount of ship-machine equipment is needed for construction, the cost is high, the construction period is long, and the recovery is difficult.

SUMMERY OF THE UTILITY MODEL

the utility model aims at providing a compound aquatic cushion cap foundation ditch retaining structure aims at solving among the above-mentioned prior art the double-walled steel cofferdam processing degree of difficulty big, the construction needs a large amount of ship machine equipment, leads to the technical problem with big, the period of construction long, the difficulty of retrieving.

in order to solve the technical problem, the utility model discloses the technical scheme who takes is:

The utility model provides a compound subaqueous cushion cap foundation ditch envelope, includes that the inner wall is vertically builds the island cofferdam, the inner wall cross section of building the island cofferdam is the rectangle, the inner wall of building the island cofferdam is equipped with one row of drilling secant pile, the well lower part of drilling secant pile is equipped with the back cover concrete that is used for bearing the cushion cap.

Preferably, the island-building cofferdam is sequentially provided with a compact pebble layer, a pebble fill layer and an anti-impact body platform from bottom to top; the bottom surface of the bottom sealing concrete is arranged below the interface of the compact pebble layer and the pebble filling layer.

Preferably, the bottom surface of the scour protection body platform is equal to the bottom of a river bed in height, the scour protection body platform is formed by stacking soil bags with clay, and the outer side of the scour protection body platform is provided with a slope.

Preferably, the drilled secant pile is formed by sequentially and mutually meshing drilled piles with the diameter of 1.2m, and the drilled secant pile is arranged in a mode that a plain concrete pile and a reinforced concrete pile are arranged at intervals.

Preferably, both sides of the drilling occlusive pile are provided with guide walls for positioning a drilling machine.

Preferably, the guide wall is a reinforced concrete guide wall, the width of the reinforced concrete guide wall is 2m, the thickness of the reinforced concrete guide wall is 40cm, the concrete grade of the reinforced concrete guide wall is C20, and the gap between the reinforced concrete guide walls on the two sides is 1.24 m.

Preferably, the top of the drilling occlusive pile is provided with a top beam, and a plurality of inner supporting pieces are arranged between the top beams at the tops of two long edges of the drilling occlusive pile at intervals.

Preferably, the top beam is 0.8m high and 1.4m wide; the inner supporting piece is a spiral steel pipe with the diameter of 0.8m and the wall thickness of 1cm, and two ends of the spiral steel pipe are fixedly connected with the top beam.

Preferably, steel plates welded and fixed with the inner steel bars of the top beam are embedded in the inner side and the top surface of the top beam, and the steel plates are welded and fixed with the end parts of the inner supporting pieces.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: compared with the prior art, the utility model discloses an inner wall at building island cofferdam bores one row of drilling secant pile, forms the whole atress of campshed, and bending resistance is strong, and has fine water-proof effects. Adopt the utility model discloses can satisfy bridge cushion cap construction and go on under anhydrous or stagnant water condition, the work progress does not have mud, the noise is low, civilized construction, environmental protection are effectual, has reduced the processing difficulty, and drilling secant pile construction need not a large amount of ship machine equipment, has solved with big costs, the period of construction is long, retrieve the technical problem of difficulty.

Drawings

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

Fig. 1 is a schematic structural view of a composite type foundation pit support structure of an underwater bearing platform provided by an embodiment of the utility model;

FIG. 2 is a top plan view of the drill bite pile of FIG. 1;

FIG. 3 is a top view of the reinforced concrete guide wall of the bored secant pile according to the present invention during the construction process;

FIG. 4 is a top plan view of the top beam of FIG. 1 engaged with the inner support member;

in the figure: 1-building an island cofferdam, 11-a compact pebble layer, 12-a pebble fill layer and 13-an anti-impact platform; 2-drilling an occlusive pile; 3-a cushion cap; 4-sealing bottom concrete; 5-reinforced concrete guide wall; 6-top beam; 7-an inner support; 8-bridge piles.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

The composite type underwater bearing platform foundation pit support structure comprises an island-building cofferdam 1 with a vertical inner wall, wherein the cross section of the inner wall of the island-building cofferdam 1 is rectangular, a row of drilling secant piles 2 are arranged on the inner wall of the island-building cofferdam 1, and bottom-sealing concrete 4 for bearing a bearing platform 3 is arranged at the middle lower part of each drilling secant pile 2. The row of drilled secant piles are drilled along the inner wall of the island-building cofferdam, so that the whole stress of the row of piles is formed, the bending resistance is strong, the closed row of piles formed by the circle of drilled secant piles has a good seepage-proofing effect, and the continuous waterproof and soil-retaining enclosing structure is formed by matching with the external island-building cofferdam.

In a preferred embodiment of the present invention, as shown in fig. 1, the island-building cofferdam 1 is composed of a dense pebble layer 11, a pebble fill layer 12 and an anti-impact body platform 13 from bottom to top; the bottom surface of the bottom sealing concrete 4 is arranged below the interface of the compact pebble layer 11 and the pebble filling layer 12. The bottom surface of the erosion-proof body platform 13 is equal to the bottom of a river bed in height, the erosion-proof body platform 13 is formed by stacking soil bags with clay, and the outer side of the erosion-proof body platform 13 is provided with a slope.

in a specific embodiment of the utility model, the drilled secant pile 2 is mutually occluded in proper order by the drilled pile that the diameter is 1.2m, and the arrangement of drilled secant pile 2 is that a plain concrete pile and a reinforced concrete pile interval form. The arrangement mode of the drilled occlusive piles is that one pile is not provided with ribs and an ultra-delayed coagulation plain concrete pile (plain pile) and a reinforced concrete pile (meat pile) are arranged at intervals, and a foundation pit enclosure structure in mutual occlusion arrangement is formed between the piles. During construction, the plain pile is constructed firstly, then the meat pile is constructed, and the construction of the meat pile is completed before concrete of the plain pile is initially set. Both the vegetable piles and the meat piles are constructed by adopting a full-casing drilling machine, and the concrete at the intersection part of the adjacent vegetable piles is cut off, so that the occlusion is realized. Compared with the traditional manual hole digging pile and the drilling close-packed pile, the drilling secant pile has the advantages of good seepage-proofing effect, small slurry pollution, good environmental protection, difficult hole collapse and the like.

In a preferred embodiment of the invention, as shown in fig. 3, both sides of the drilling bitten pile 2 are provided with guide walls 5 for positioning of the drilling machine. The guide wall 5 is a reinforced concrete guide wall, the width of the reinforced concrete guide wall is 2m, the thickness of the reinforced concrete guide wall is 40cm, the concrete grade of the reinforced concrete guide wall 5 is C20, the gap between the reinforced concrete guide walls 5 on two sides is 1.24m, and a surplus width of 2cm is reserved on each side. The reinforced concrete guide wall can ensure accurate positioning of the drilled secant pile, improve the positioning precision and the positioning efficiency of the orifice of the drilled secant pile, ensure the stability of a drilling machine and bear construction load. In order to ensure that the machinery smoothly enters and exits, the top surface of the poured reinforced concrete guide wall is controlled to be consistent with the top elevation of the island-building cofferdam. Before the guide wall concrete is constructed, the top surface of the island is excavated according to the position of the guide wall, and then reinforcing steel bars are bound, templates are installed and the concrete is poured after the excavation is finished.

in addition, the guide wall can also adopt a recycled steel mould guide wall.

In a preferred embodiment of the present invention, as shown in fig. 1, the top of the drilling secant pile 2 is provided with a top beam 6, and a plurality of inner supporting members 7 are arranged between the two long edge top beams 6 of the drilling secant pile 2 at intervals. Specifically, the top beam 6 is 0.8m high and 1.4m wide; the inner supporting piece 7 is a spiral steel pipe with the diameter of 0.8m and the wall thickness of 1cm, and two ends of the spiral steel pipe are fixedly connected with the top beam 6. An excavation internal support is provided by a plurality of internal supports.

In order to facilitate the connection and fixation of the inner supporting piece and the top beam, steel plates which are welded and fixed with the inner steel bars of the top beam 6 are embedded in the inner side and the top surface of the top beam 6, and the steel plates are welded and fixed with the end parts of the inner supporting pieces 7.

The utility model discloses a concrete application as follows: considering that the main pier foundation of the bridge is an underwater foundation, the main pier adopts a drilled pile foundation with the diameter of 1.8m, and the pile length is 35 m; the bearing platform is a rectangle of 12 multiplied by 3.5m, is a low pile bearing platform and is completely buried in a riverbed, the foundation construction adopts the island and cofferdam building mode to carry out the pile foundation construction, then a support pile is arranged, a foundation pit of the bearing platform is excavated by water, the bottom sealing concrete is poured, and finally the process of pumping water and dry construction of the bearing platform is carried out. In order to ensure the safety of foundation pit excavation and achieve the effect of water sealing of the side wall of the foundation pit in the later period, the foundation pit supporting system adopts a form of drilling secant pile and supporting. The secant pile is a drilled pile with the diameter of 1.2m, the pile length is 20m, the anchoring length is 11.89m, the cantilever length is 8.11m, the meat and vegetable are matched, the meat pile is made of C30 reinforced concrete, the vegetable pile is made of C20 vegetable concrete, and the secant between the meat and the vegetable is 0.25 m. 48 meat piles and 48 vegetable piles are arranged in a single foundation pit. The pile top is provided with a reinforced concrete top beam, the height of the top beam is 0.8m, and the width of the top beam is 1.4 m. And after the construction of the top beam is finished, arranging an inner supporting piece at every 7m of the inner side of the top beam. The inner supporting piece is a spiral steel pipe with the diameter of 800mm and the wall thickness of 1 cm.

The specific process flow is as follows: the construction method comprises the steps of construction preparation, island building, cofferdam building, hole drilling secant pile construction, inner supporting piece arrangement between top beams, foundation pit excavation, bottom sealing concrete pouring, water pumping in the foundation pit and bearing platform construction.

The technical control key points are as follows:

1. preparing for construction, namely building an island and a cofferdam;

The foundation pit is a bridge foundation pit, and is 29.8m long and 13.8m wide. Depth 8.1 m. The fender pile is adopted for vertical excavation, and because the bridge foundation is positioned in the Chongzhou Xijiang river, a construction platform needs to be built in the Xijiang river in a form of island building and cofferdam. The construction platform is 48.4m long and 32.4m wide, is filled with sand and pebbles, and is stacked with clay around to form a soil bag.

2. Constructing a drilling secant pile;

3. And (3) guide wall construction: before the guide wall concrete is constructed, the top surface of the island is excavated according to the position of the guide wall, and after the excavation is finished, reinforcing steel bars are bound, templates are installed, and the concrete is poured.

4. Mounting of steel casing

The steel casing is rolled by a steel plate with the wall thickness of 1cm, the diameter of the steel casing is 1.2m, then the steel casing is placed downwards by a pipe rolling machine, equipment needs to be leveled before the pipe rolling machine is used for ensuring the verticality of the steel casing, and the pipe rolling machine is used for fixing the steel casing and cutting sand gravel or plain pile concrete until the bottom of a hole. And after the pipe twisting machine finishes the construction of one steel casing, hoisting the steel casing to the next hole site by using the crawler crane for implementation. And under the condition of ensuring certain concrete burial depth in the concrete pouring process, the steel protective cylinder is lifted by using a pipe rolling machine while pouring concrete, and one hole is poured to another hole site after being formed.

5. Drilling construction:

The drilling construction adopts a 280-type rotary drilling rig, firstly constructs plain piles, then constructs meat piles, and strictly controls the deviation and verticality deviation of hole piles in the drilling process, if the deviation occurs, the hole piles need to be corrected in time, so that the incomplete occlusion phenomenon is avoided, and the water sealing effect is not influenced.

6. Underwater concrete pouring:

The underwater concrete pouring adopts a guide pipe method, and the pouring guide pipe adopts a 300mm fast bayonet vertical lifting guide pipe. The guide pipe is assembled before use, and according to the required length of the hole depth pre-assembly, the guide pipe is straight and subjected to tension and watertight tests, so that the good state of the guide pipe is ensured. Carefully operating when the guide pipe is placed down to avoid hanging and touching the reinforcement cage and the hole wall, gently placing the guide pipe at the bottom of the hole, and then lifting the guide pipe upwards by 25-40 cm. And comparing the length with the theoretical length of the conduit, fixing the conduit on a hole seat of a pouring platform after the conduit is matched, connecting a concrete primary pouring funnel, checking the thickness of sediment at the bottom of the hole, and after meeting the standard requirement and being agreed by a supervision engineer, beginning to pour concrete. The concrete is conveyed to the pier position by the concrete transport vehicle, and the cantilever crane pump is conveyed to the pile position to directly place the concrete into the aggregate bin. And (3) pouring the underwater concrete by using a ball pulling method, wherein the embedded depth of the bottom end of the guide pipe is more than 1.0m after the concrete stored in the funnel and the total amount of the concrete in the funnel are pulled out before pouring.

according to design requirements, the plain pile is made of C20 underwater concrete, the meat pile is made of C30 underwater reinforced concrete, the plain pile part needs to be cut to achieve the occlusion effect during construction of the meat pile, the initial setting time of the concrete needs to be controlled during underwater concrete pouring, a retarder can be properly added into the concrete of the plain pile, and the setting delay time of the plain pile is controlled within 30 ~ 40 hours generally according to design and field construction conditions.

7. And (3) supporting in the foundation pit: in the foundation pit, an inner supporting piece is arranged on a top beam of the foundation pit, and the inner supporting piece is a spiral steel pipe with the diameter of 0.8m and the wall thickness of 1 cm. The plane position is totally provided with three spiral steel pipes (as shown in figure 4).

Each inner support piece is 13.6m long and 2.65t heavy, the inner support piece is integrally lengthened on a flat ground before construction, pipe joint corresponding openings are kept on the same axis, when two spiral steel pipes are lengthened, rust, oil stain, water vapor and sundries within the range of 20 ~ 30mm near a joint must be removed firstly, then the two spiral steel pipes are connected by a wrapping plate, and the wrapping plate is integrally hoisted and installed after the overlapping length of the wrapping plate is not less than 0.4 m.

The inner supporting piece is connected with the top beam in a welding mode. When the top beam is constructed, 1cm steel plates are embedded in the inner side and the top surface of the top beam, the steel plates and the top beam steel bars are welded into a whole, and after the spiral steel pipe is hoisted in place, the flange of the spiral steel pipe is directly welded with the embedded steel plates.

8. Excavation of a foundation pit:

during main bridge foundation ditch excavation, because the foundation ditch degree of depth is darker, and because not pouring the back cover concrete, unable precipitation in the foundation ditch, the excavator can't enter the hole excavation, according to cushion cap width and foundation ditch degree of depth, the foundation ditch divide into two-layer excavation, and the first layer is foundation ditch top surface to 4m below the foundation ditch, and this layer adopts 330 type excavator (fill capacity 1.5m 3) to have water excavation. In order to improve the excavation speed, two excavators excavate simultaneously in each foundation ditch. The second floor is 4m below the foundation ditch to the bottom of the back cover concrete, and the excavation is deeper, and because the bridge pile head hinders, can't adopt the excavator excavation, so in 4m below the foundation ditch to the bottom of the back cover concrete elevation scope, the foundation ditch excavation adopts the grab bucket to go out native.

9. And (3) pouring bottom sealing concrete:

After the foundation pit is excavated to the bottom of the designed back cover concrete, a pouring frame is erected on the platform, the back cover concrete is poured, the thickness of the back cover concrete is 1.5m, 24 blanking points are arranged in the whole area, and each blanking single-action radius is considered according to 4 m. The pouring sequence is from upstream to downstream. And when concrete is poured, the concrete is transported to the position near the pier body by adopting a concrete transport vehicle, and the cantilever crane pump pumps the concrete for pouring.

10. pumping water in the foundation pit:

After the pouring of the bottom sealing concrete is finished, 4 water pumps with 4.5KW and 150mm pipe diameters are adopted to drain accumulated water in the cofferdam. And grouting a certain position in the bearing platform if the water inflow amount of the position is more than 10L/min in the process of pumping water of the foundation pit. The grouting material is cement-water glass double-liquid slurry. And after the water pumping is finished, constructing a bearing platform according to the design drawing requirements.

In the above description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be implemented in other ways different from the one described herein, and those skilled in the art may similarly generalize the present invention without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed above.

Claims (9)

1. The utility model provides a compound subaqueous cushion cap foundation ditch retaining structure which characterized in that: the island cofferdam comprises an island cofferdam with a vertical inner wall, the cross section of the inner wall of the island cofferdam is rectangular, a row of drilling secant piles are arranged on the inner wall of the island cofferdam, and bottom sealing concrete used for bearing a bearing platform is arranged at the middle lower part of each drilling secant pile.

2. The composite type underwater cushion cap foundation pit support structure of claim 1, characterized in that: the island-building cofferdam comprises a compact pebble layer, a pebble fill layer and an anti-impact body platform from bottom to top in sequence; the bottom surface of the bottom sealing concrete is arranged below the interface of the compact pebble layer and the pebble filling layer.

3. The composite type underwater cushion cap foundation pit support structure of claim 2, characterized in that: the bottom surface of the scour protection body platform is equal to the bottom of a river bed in height, the scour protection body platform is formed by clay stacking soil bags, and the outer side of the scour protection body platform is provided with a slope.

4. The composite type underwater cushion cap foundation pit support structure of claim 1, characterized in that: the drilled secant pile is formed by sequentially and mutually meshing drilled piles with the diameter of 1.2m, and the drilled secant pile is arranged in a mode that a plain concrete pile and a reinforced concrete pile are arranged at intervals.

5. The composite type underwater cushion cap foundation pit support structure of claim 4, wherein: and guide walls for positioning the drilling machine are arranged on two sides of the drilling secant pile.

6. the composite type underwater cushion cap foundation pit support structure of claim 5, characterized in that: the guide wall is made of reinforced concrete, the width of the reinforced concrete guide wall is 2m, the thickness of the reinforced concrete guide wall is 40cm, the concrete grade of the reinforced concrete guide wall is C20, and the gap between the reinforced concrete guide walls on the two sides is 1.24 m.

7. The composite type underwater cushion cap foundation pit support structure of any one of claims 1-6, wherein: the top of the drilling secant pile is provided with a top beam, and a plurality of inner supporting pieces are arranged between the top beams at the tops of two long edges of the drilling secant pile at intervals.

8. The composite type underwater cushion cap foundation pit support structure of claim 7, wherein: the top beam is 0.8m high and 1.4m wide; the inner supporting piece is a spiral steel pipe with the diameter of 0.8m and the wall thickness of 1cm, and two ends of the spiral steel pipe are fixedly connected with the top beam.

9. The composite type underwater cushion cap foundation pit support structure of claim 7, wherein: and steel plates welded and fixed with the inner steel bars of the top beam are embedded in the inner side and the top surface of the top beam, and the steel plates are welded and fixed with the end parts of the inner supporting pieces.