CN104074197A - Large-diameter thin-walled tubular pile composite anchor rod type foundation pit support structure and construction method thereof - Google Patents

Abstract

The invention discloses a large-diameter thin-walled cylindrical pile composite anchor rod type foundation pit enclosure structure and a construction method thereof. The enclosure structure design mainly involves water-stop curtains, thin-walled cylindrical piles, passive zone reinforcement piles, top beams and The connection and structural design of purlins. The construction process of the enclosure structure mainly includes the construction of water-stop curtain, the construction of large-diameter thin-walled cylindrical piles, the construction of reinforced piles in the passive zone, and the construction of the first layer of anchor rods (digging foundation pit→drilling rig Hole forming → anchor body entry → anchor section grouting → free end grouting → installation of fastening nut), the second layer of anchor construction (digging the foundation pit → drilling rig to form a hole → anchor body entry → anchor section grouting → free end grouting) and purlin construction of the first layer (binding purlin reinforcement → installing purlin formwork → pouring concrete). Through special structural design and construction, the traditional large-diameter thin-walled piles, which are mainly used for foundation treatment, are combined with high-strength anchor rods and purlins to enclose the foundation pit, achieving economical, environmental protection and high-efficiency effects, and laying foundation for the subsequent foundation pit construction. Bring great convenience.

Description

Large-diameter thin-walled cylindrical pile composite anchor type foundation pit enclosure structure and its construction method

technical field

The invention relates to an enclosure structure for a foundation pit of a building, and further relates to a new effective structural design and a corresponding construction method for the enclosure enclosure of a foundation pit in a soft clay area.

Background technique

The development of China is mainly the development of the economy. The development of the economy brings the development of the construction industry. The development direction of the construction industry is bound to be taller, bigger, better and more beautiful. The guarantee of this direction is to lay a solid foundation for the construction. Foundation, which also requires doing more in foundation pit enclosure. On the other hand, due to less and less construction land, more and more building construction has to be carried out in soft soil areas with poor foundation conditions, which also puts forward more specifically how to better protect foundation pits in soft soil areas Such a technical problem.

At present, the foundation pit enclosure structures in soft soil areas mainly include: soil nail wall, underground diaphragm wall, SMW construction method, and cast-in-place pile plus internal support. The soil nail wall forms a composite soil with the main purpose of enhancing the stability of the slope by setting soil nails of a certain length and density in the soil and interacting with the soil. It is an active control mechanism. The interaction between soil nails and soil As a result, a composite soil body that can improve the strength and stiffness of the undisturbed soil is formed, the deformation and failure form of the soil slope are changed, and the overall stability of the soil slope is significantly improved. However, the soil nail wall has the disadvantage of lacking a reasonable control theory for displacement calculation, and it is not suitable for soft soil foundation pits with strict displacement requirements. The underground diaphragm wall adopts a kind of trenching machine on the ground, along the peripheral axis of the deep excavation project, under the condition of mud retaining wall, excavates a narrow and long deep groove, after clearing the groove, hang steel bars in the groove, Then use the conduit method to fill the underwater concrete to build a unit tank section, and then build a continuous reinforced concrete wall underground as a foundation pit enclosure structure for water interception, seepage prevention, load bearing, and water retention. The enclosure structure of the underground diaphragm wall is difficult to deal with the waste mud generated during the construction process, the trench wall is easy to collapse after the trench is excavated, the cost is high, and the operation level of the construction unit is also required to be high. The SMW construction method enclosure structure (stiff cement-soil continuous wall) uses a special multi-shaft mixer to drill and cut the soil on the spot, and at the same time inject the cement slurry into the soil from the front end of the drill bit. H-shaped steel or other core materials are inserted into the mixing body to form an underground continuous wall. Its main disadvantage is that the enclosure rigidity is small and the deformation after excavation is large. Cast-in-situ pile plus internal support refers to the use of bored piles as surrounding protection piles, top pressure beams are set on the top of the surrounding piles, water-stop curtains are set on the outside of the foundation pit and drainage measures are set on the inside of the foundation pit, and then a layer is set on the inside of the foundation pit. Or multi-layer purlins and set up an inner support enclosure structure at the corresponding purlins. This enclosure structure has the disadvantages of serious mud pollution, difficulty in subsequent mud treatment, high energy consumption for drilling, difficulty in ensuring the quality of enclosure piles, and inconvenient construction in the foundation pit. March 18, 2014.

Contents of the invention

The technical problem mainly solved by the present invention is to provide a safe, environment-friendly, efficient, economical design and design of a large-diameter thin-walled cylindrical pile enclosure structure that is convenient for subsequent foundation pit excavation construction for foundation pits in soft soil areas. its construction method.

The technical solution of the present invention is: a large-diameter thin-walled cylindrical pile composite anchor-type foundation pit enclosure structure, which is characterized in that it includes a cement mixing pile water-stop curtain, a large-diameter thin-walled cylindrical pile, the first layer of anchor rods and the second The second layer of anchor rods, top beams, surrounding purlins and reinforcement piles in the passive area, the water-stop curtain is located at the periphery of the foundation pit enclosure structure, and is composed of a plurality of single-row cement mixing piles distributed around the foundation pit; the large The diameter thin-walled cylindrical pile is a cast-in-place thin-walled cylindrical pile, and is located inside the water-stop curtain. The large-diameter thin-walled cylindrical pile includes a thin-walled pile body and a pile head. The pile head has a pile head through hole. The pile top is poured There is a top beam that enhances the overall stability of each surrounding protection pile, and a first tunnel and a second tunnel are sequentially opened on the thin-walled pile body along the depth direction, and the first tunnel and the second tunnel both include the pile body in the pile body Holes and soil holes in the soil, the first layer of anchors are inserted into the first tunnel and reach the soil hole, cement slurry is poured between the first tunnel and the first layer of anchors, the first layer The first hole where the anchor rod is inserted is poured and anchored with a supporting plate, the fastening nut is threaded with one end of the first layer of anchor rod and the supporting plate is pressed against the thin-walled pile, and the second layer of anchor rod is inserted into the second hole And reach the soil hole, cement slurry is poured between the second tunnel and the second layer of anchor rods, the second layer of anchor rods reserves a certain length of rod body reinforcement outside the second tunnel, and the internal reinforcement of the surrounding purlin and the rod body reinforcement Binding, the surrounding purlins are made of concrete; the reinforcement piles in the passive area are located inside the large-diameter thin-walled cylindrical piles, and are made of cement mixing piles driven in the soil.

The construction method of the above-mentioned large-diameter thin-walled cylindrical pile composite anchor rod type foundation pit enclosure structure includes the following construction steps:

(1) Waterstop curtain construction

The water-stop curtain is located on the periphery of the foundation pit enclosure structure, and is surrounded by a large number of single-row cement mixing piles distributed along the foundation pit;

(2) Construction of large-diameter thin-walled cylindrical piles

① Embed the prefabricated pile head of the large-diameter thin-walled cylindrical pile between the inner steel cylinder formwork and the outer steel cylinder formwork;

②Install a vibration clamp on the top of the rigid cylinder formwork to fix the high-frequency vibrator. After the high-frequency vibrator is adjusted in place, press the inner steel cylinder formwork, the outer steel cylinder formwork and the prefabricated pile head into the soil until the prefabricated pile head reaches design depth;

③ Loosen the vibration clamp on the top of the formwork, put the prefabricated reinforcement cage into the annular formwork cavity, pour concrete through the concrete pouring port on the outer steel cylinder formwork, and lift the steel cylinder formwork at the same time;

④ Repeat the above steps to construct the next large-diameter thin-walled cylindrical pile until all the large-diameter thin-walled cylindrical piles required for the enclosure of the foundation pit are completed;

⑤ After the concrete of the retaining piles reaches the design strength, remove the miscellaneous soil on the top of the retaining piles in the foundation pit, and pour the top beams to enhance the overall stability of the retaining piles.

(3) Construction of reinforcement piles in the passive zone

The reinforced piles in the passive zone are located inside the large-diameter thin-walled cylindrical piles, and are composed of cement mixing piles driven in the soil.

(4) The first layer of anchor rod construction

①Dig the foundation pit down to 1m below the design elevation of the first layer of anchor bolts;

②According to the construction design drawing, use a total station to measure and set out to determine the design hole position and anchor hole azimuth of the anchor bolt, and mark it on the enclosure pile;

③The drilling rig is in place, and the hole is drilled at the marked hole position;

④Push the anchor rod into the tunnel forcefully and consistently, and do not rotate the rod body during the pushing process; use a pressure piston type grouting pump to grout the tunnel, push the cement slurry into the hole through the grouting pipe, and then grout, and install it on the anchor rod Anchor supporting plates are poured at the opening of the tunnel and fastening nuts are installed.

(5) Construction of the second layer of anchor rods

①Dig the foundation pit down to 1m below the design elevation of the second floor anchor;

②According to the construction design drawing, use a total station to measure and set out to determine the design hole position and anchor hole azimuth of the anchor bolt, and mark it on the enclosure pile;

③The drilling rig is in place, and the hole is drilled at the marked hole position;

④Consistently push the bolt into the hole, and do not rotate the rod body during the pushing process; use the pressure piston type grouting pump to grout the hole, push the cement slurry into the hole through the grouting pipe, and then grout; reserve a certain length The rod body reinforcement of the anchor rod is outside the tunnel;

(6) Purlin construction on the first layer

① Bind the rod body reinforcement outside the second channel reserved for the second layer of anchor rods with the first layer of purlin reinforcement;

②Install the formwork for the first layer of purlins and pour concrete;

4. According to the construction method of large-diameter thin-walled cylindrical pile composite anchor-type foundation pit enclosure structure according to claim 1, it is characterized in that: the prefabricated steel cage in the sub-step ③ of the construction step (2) has reserved The hole required for the anchor channel is that the anchor can pass through the cylindrical pile and compound it with the minimum damage to the cylindrical pile; the concrete pouring in the construction steps (2)-③ is segmental pouring and segmental vibration, and the steel formwork is segmented lift.

Compared with the existing technology, the large-diameter thin-walled cylindrical pile composite anchor type foundation pit enclosure structure and construction method of the present invention have the following significant advantages and beneficial effects:

From a macro point of view, the foundation pit enclosure structure and construction process of the present invention mainly highlight the advantages of safety, environmental protection, economy and convenience. First of all, the present invention makes the anchor rod pass through the cylindrical pile with minimum damage to the cylindrical pile by reserving the hole of the anchor rod for the reinforcement cage of the cylindrical pile, and further utilizes the reserved anchor rod body reinforcement as a bridge to realize the When the thin wall of the cylindrical pile is destroyed, the cylindrical pile, the anchor rod and the purlin are connected to form an enclosure structure with very good overall stability and strong resistance to lateral deformation, which has good safety. At the same time, this enclosure structure The absence of internal support can save a lot of waste of resources (the internal support is generally a waste of subsequent dismantling) and brings great convenience to the subsequent construction in the foundation pit, which embodies the environmental protection, economy and convenience of the present invention. Secondly, the use of large-diameter thin-walled cylindrical piles as enclosure piles does not require the use of large-scale machinery such as drilling machines and pile drivers, does not require a large amount of mud wall protection, and does not need to excavate a large amount of site soil, thereby reducing the construction process. Noise pollution in the environment, reduce potential safety hazards, avoid follow-up transportation and treatment of mud and earthwork, embodies the safety and environmental protection of the present invention; finally, although the enclosure pile has a large diameter (has good overall stability and lateral resistance Deformability), but the required amount of concrete and reinforcement is far less than other types of enclosure piles with similar diameters, reflecting the economy of the present invention.

Description of drawings

Fig. 1 is a partial front view of the compound structure of the enclosure pile, anchor rod and enclosure purlin of the foundation pit enclosure structure involved in the present invention.

Fig. 2 is a schematic diagram of a side section partial structure of the foundation pit enclosure structure involved in the present invention.

Figure 3 is a schematic diagram of the large-diameter thin-walled cylindrical pile structure and construction of the foundation pit enclosure structure involved in the present invention.

Figure 4 is a detailed schematic diagram of the composite structure of the first layer of anchor rods and surrounding protection piles of the foundation pit protection structure involved in the present invention.

Fig. 5 is a structural schematic diagram of the second layer of anchor rods of the foundation pit enclosure structure involved in the present invention.

Fig. 6 is a detailed schematic diagram of the composite structure of the first layer of surrounding purlins and surrounding protection piles in Fig. 5 .

Fig. 7 is a top view partial structural schematic diagram of the foundation pit enclosure structure involved in the present invention.

Fig. 8 is a schematic diagram of the local structure of the first layer of the surrounding purlins of the foundation pit enclosure structure involved in the present invention.

As shown in the figure: 1. Large-diameter thin-walled cylindrical pile, 2. Pile head, 3. Top beam, 4. The first layer of anchor rods, 5. The second layer of anchor rods, 6. The first layer of purlins, 7. Outer steel cylinder formwork, 8. Inner steel cylinder formwork, 9. High-frequency vibrator, 10. Vibration clamp, 11. Concrete pouring opening, 12. Pile head through hole, 13. Foundation pit, 14. Anchorage section, 15. Free section, 16, anchor hole, 17, supporting plate, 18, fastening nut, 19, grouting pipe, 20, tube pile reinforcement cage, 21, hole, 22, rod body reinforcement, 23, first layer of purlin reinforcement , 24, high-strength steel wire, 25, passive zone reinforcement pile, 26, water-stop curtain.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing and specific embodiment:

Figures 1 to 8 are just one embodiment of the present invention, and the enclosure structure of the foundation pit shown in the embodiment is a large-diameter thin-walled cylindrical pile compounded with a layer of purlins and two layers of anchor rods.

Its specific structure design is as follows:

Referring to Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, and Fig. 8, the large-diameter thin-walled cylindrical pile composite anchor rod foundation pit enclosure structure provided by this embodiment includes cement Stirring pile water-stop curtain 26, large-diameter thin-walled cylindrical pile 1, anchor rod 4 of the first layer, anchor rod 5 of the second layer, top beam 3, purlin 6 of the first layer and reinforcement pile 25 in the passive area. The water-stop curtain 26 is located at the periphery of the foundation pit enclosure structure, and is composed of a plurality of single-row cement mixing piles distributed around the foundation pit. The diameter of the cement mixing piles is 500mm, the pile spacing is 350mm, and the design depth is 8m. The cement is Portland cement of grade 32.5, and the water-cement ratio is controlled at about 0.5. The large-diameter thin-walled cylindrical pile 1 is a cast-in-place thin-walled cylindrical pile and is located inside the water-stop curtain 26. The large-diameter thin-walled cylindrical pile 1 includes a thin-walled pile body and a pile head 2, and the pile head 2 has a pile head Through holes, the wall thickness of the large-diameter thin-walled cylindrical pile 1 is 200mm, the outer diameter of the cylindrical pile is 1000mm, the pile spacing is 1000mm, and the design depth is 10m. The top of the pile is poured with a pressure beam that enhances the overall stability of the surrounding protection piles 3. The top of the large-diameter thin-walled tubular pile 1 is embedded in the top of the top beam 3 miles, and the concrete grade is C30. On the thin-walled pile body, there are two anchor tunnels 16 successively along the depth direction. The anchor tunnels 16 are respectively the first tunnel and the second tunnel, and the first tunnel and the second tunnel all include piles in the pile body. The body hole and the soil hole in the soil, the first layer of anchor rod 4 is inserted into the first tunnel and reaches the soil hole, cement slurry is poured between the first tunnel and the first layer of anchor rod 4, the The first hole in which the first layer of anchor rods 4 is inserted is poured and anchored with a supporting plate 17, and the fastening nut 18 is threadedly connected with one end of the first layer of anchor rods 4 and the supporting plate 17 is pressed against the thin-walled pile body. The second layer of anchor rod 5 is inserted into the second tunnel and reaches the soil hole, cement slurry is poured between the second tunnel and the second layer of anchor rod 5, and a certain length of rod body reinforcement 22 is reserved for the second layer of anchor rod 5. Outside the second channel, the first layer of anchor rods 4 and the second layer of anchor rods 5 are finished rolled rebar, and the drilling depth of the anchor rod channel 16 is 5m and the aperture is 80mm. The internal steel bar 23 of the purlin 6 is bound to the steel bar 22 of the pole body, and the purlin 6 is made of concrete. The reinforcement pile 25 in the passive area is located inside the large-diameter thin-walled cylindrical pile 1, and is composed of cement mixing piles set in the soil body. The specific construction is: every 3m in the passive area is used as a reinforcement node, and cement mixing piles are set for reinforcement. Three rows of reinforcement piles 25 are arranged, each row has 5 piles, the diameter of the piles is 500mm, the pile spacing is 350mm, the row spacing is 500mm, and the design depth is 10m.

Its specific construction method includes the following steps:

(1) Waterstop curtain 26 construction

The water-stop curtain 26 is located on the periphery of the foundation pit enclosure structure, and is surrounded by a large number of single-row cement mixing piles distributed around the foundation pit. The secondary grouting and secondary mixing process is adopted, and the first mixing head sinks and mixes. To the design depth, then raise the mixing head to the design surface elevation while grouting, then sink the mixing head to the design depth for the second time, and raise the mixing head to the design surface elevation while grouting for the second time, forming cement mixing Pile waterstop curtain 26.

(2) Construction of large-diameter thin-walled cylindrical pile 1

① Embedding the prefabricated pile head 2 of the large-diameter thin-walled cylindrical pile 1 between the inner steel cylinder formwork 8 and the outer steel cylinder formwork 7, the outer steel cylinder formwork 7 is provided with a concrete pouring port 11, and the prefabricated pile head 2 It is a conical pile head and the pile head through hole 12 is prefabricated to output the soft soil in the subsidence process;

②Install the vibration clamp 10 on the top of the rigid cylinder formwork to fix the high frequency vibrator 9. After the high frequency vibrator 9 is adjusted in place, press the inner steel cylinder formwork 8, the outer steel cylinder formwork 7 and the prefabricated pile head into the soil until The prefabricated pile head reaches the design depth, and the process of pressing down the formwork needs to continuously adjust the verticality of the pile body;

③ Loosen the vibration clamp 10 on the top of the formwork, put the prefabricated steel cage 20 into the annular formwork cavity, pour concrete through the concrete pouring port 11 on the outer steel cylinder formwork 7, adopt segmental pouring, and lift the steel cylinder at the same time Formwork, the steel cage 20 has reserved the hole 21 of the bolt tunnel at the design position of each layer of bolt;

④Repeat the above steps to construct the next large-diameter thin-walled cylindrical pile 1 until all the surrounding protection piles required for the foundation pit are completed;

⑤ After the concrete of the retaining piles reaches the design strength, remove the miscellaneous soil on the top of the retaining piles in the foundation pit, and pour the top beam 3 to enhance the overall stability of the retaining piles.

(3) Construction of reinforcement pile 25 in the passive area

The reinforcement piles 25 in the passive area are located inside the large-diameter thin-walled cylindrical pile 1, and are composed of cement mixing piles driven in the soil. The reinforcement piles in the passive area are constructed in rows, and the construction of each row is as the above-mentioned cement-soil mixing pile construction method.

(4) Construction of anchor rod 4 on the first layer

①Dig the foundation pit 13 to the place 1m below the design elevation of the anchor rod 4 of the first layer, and remove the miscellaneous soil on the retaining pile;

②According to the construction design drawing, use a total station to measure and set out to determine the design hole position of the anchor rod and the azimuth angle of the anchor hole, and mark it on the enclosure pile 1. The azimuth angle is consistent with the angle of the hole 21 reserved on the prefabricated steel cage of the barrel pile ;

③ The drilling rig is in place, and the hole is drilled at the marked hole position. During the drilling process, a specific drilling speed is maintained to prevent excessive damage to the thin wall of the surrounding protection pile;

④Re-inspect the drilled hole before installing the bolt, and clean up the collapsed hole and dropped blocks;

⑤Consistently push the anchor rod into the hole 16, do not rotate the rod body during the pushing process, and ensure that the anchor rod body 15 is pushed to the predetermined depth;

⑥ Use a pressure piston type grouting pump to grout the tunnel, push the grout into the hole through the grouting pipe 19, and then grout. The grouting process is two grouting. Keep the length of the anchoring section full, and after the anchoring section has a certain strength, perform the second grouting on the free section 15, and finally inject the anchoring grout at the end of the hole;

⑦Concrete the anchor supporting plate 17 at the opening of the anchor hole and install the fastening nut 18;

(5) Construction of the second layer anchor rod 5

①Dig the foundation pit down to a place 1m below the design level of the anchor rod 5 on the second floor;

②According to the construction design drawing, use a total station to measure and set out to determine the design hole position of the anchor rod and the azimuth angle of the anchor hole, and mark it on the enclosure pile 1. The azimuth angle is consistent with the angle of the hole 21 reserved on the prefabricated steel cage of the barrel pile ;

③ The drilling rig is in place, and the hole is drilled at the marked hole position. During the drilling process, a specific drilling speed is maintained to prevent excessive damage to the thin wall of the surrounding protection pile;

④Re-inspect the drilled hole before installing the bolt, and clean up the collapsed hole and dropped blocks;

⑤Push the anchor rod into the hole 16 consistently with force, do not rotate the rod body during the pushing process, and ensure that the anchor body is pushed to the predetermined depth, and reserve a certain length of the rod body steel bar 22 of the second layer of anchor rod 5 in the hole 16 outside;;

⑥ Use a pressure piston type grouting pump to grout the tunnel, push the grout into the hole through the grouting pipe 19, and then grout. The grouting process is two grouting. Keep the length of the anchoring section 14 full, and after the anchoring section 14 has a certain strength, carry out the second grouting to the free section 15 of the anchor rod, and finally inject the anchor grout at the end of the hole.

(6) Construction of purlin 6 on the first floor

① Bind the rod body reinforcement 22 outside the tunnel reserved for the second layer of anchor rods with the first layer of purlin reinforcement 23, and the second layer of reserved rod body reinforcement 22 is designed to be completely poured in the first layer of purlin 6 body, The binding steel bar between the anchor rod and the purlin steel bar is high-strength steel wire 24;

②Install the formwork of purlin 6 on the first layer and pour concrete;

Through the above construction, the foundation pit enclosure structure of the present invention is obtained.

See Figure 1~Figure 7. The present invention can also have other embodiment, promptly foundation pit enclosing structure has multi-layer such as three-layer anchor rod 5 and two-layer enclosing purlin 6, and its construction method is specifically as follows:

(1) Construction of cement mixing pile water-stop curtain 26

(2) Construction of large-diameter thin-walled cylindrical pile 1

(3) Construction of reinforcement pile 25 in the passive area

(4) Construction of anchor rod 4 on the first layer

(5) Construction of the second layer anchor rod 5

(6) Construction of purlin 6 on the first floor

[The above (1)~(6) construction steps are the same as the previous construction example]

(7) Construction of the third layer of anchor rods

①Dig the foundation pit to the point 1m below the design elevation of the anchor bolt on the third floor;

②Repeat the construction process of ②~⑥ in (2) above (no need to pour pallets and install fastening nuts), and reserve a certain length of rod body reinforcement outside the tunnel;

(8) Purlin construction on the second floor

① Bind the rod body reinforcement outside the channel reserved for the third layer of anchor rods with the surrounding purlin reinforcement. The third layer of reserved rod body reinforcement is designed to be poured entirely in the second layer of surrounding purlin body. The gap between the anchor rod and the surrounding purlin reinforcement Binding steel bars are high-strength steel wires;

②Install formwork for the purlins on the second floor and pour concrete;

Through the above construction, another embodiment of the foundation pit enclosure structure of the present invention is obtained.

Claims (4)

1. a large diameter thin wall cylinder stake compound anchor rod-type foundation pit enclosure structure, it is characterized in that: comprise cement mixing pile water stopping curtain, the stake of large diameter thin wall cylinder, first floor anchor pole and second layer anchor pole, capping beam, enclose purlin and passive area reinforcing pile, the periphery of described water-stop curtain in foundation pit enclosure structure, and formed by the multiple single cement mixing pile around distributing along foundation ditch, the stake of described large diameter thin wall cylinder is Cast-in-situs type thin-walled cylinder pile, and in water-stop curtain inner side, the stake of large diameter thin wall cylinder comprises thin-walled pile body and pile crown, pile crown is with pile crown through hole, the capping beam that strengthens each fender post resistance to overturning is built in described stake top casting, on described thin-walled pile body, offer successively the first duct and the second duct along depth direction, described the first duct and the second duct include pile body hole in pile body and the soil body hole in the soil body, described first floor anchor pole inserts the first duct and arrives in soil body hole, between the first duct and first floor anchor pole, be perfused with cement paste, the first opening of the channel that described first floor anchor pole inserts is built anchoring supporting plate, clamp nut is connected with the threaded one end of first floor anchor pole and supporting plate is pressed on thin-walled pile body, described second layer anchor pole inserts the second duct and arrives in soil body hole, between the second duct and second layer anchor pole, be perfused with cement paste, the body of rod reinforcing bar of the reserved certain length of described second layer anchor pole is outside the second duct, enclose the inner reinforcing bar of purlin and body of rod reinforcing bar binding, enclosing purlin is made up of concrete, described passive area reinforcing pile is in large diameter thin wall cylinder stake inner side, and is made up of the cement mixing pile being piled in the soil body.

2. large diameter thin wall cylinder stake compound anchor rod-type foundation pit enclosure structure, is characterized in that: the diameter that forms the cement mixing pile of described water-stop curtain is that 500mm, pile spacing are that 350mm, projected depth are 8m; The cylinder pile lining of described large diameter thin wall cylinder stake 1 thick for 200mm, a cylinder stake external diameter be that 1000mm, pile spacing are that 1000mm, projected depth are 10m; Described passive area as a reinforcing joint, arranges Reinforcement with Cement-mixed Piles every 3m, and reinforcing pile 25 arranges three rows, every row's 5 piles, and the diameter of stake is 500mm, and pile spacing is 350mm, and row's spacing is 500mm, and projected depth is 10m; The body of rod of described first floor anchor pole and second layer anchor pole is fining twisted steel, and the degree of depth in described the first duct and the second duct is 5m, aperture 80mm.

3. a construction method for large diameter thin wall cylinder stake compound anchor rod-type foundation pit enclosure structure, is characterized in that: comprise following construction sequence:

(1) water-stop curtain construction

The periphery of water-stop curtain in foundation pit enclosure structure, adopts a fairly large number of single cement mixing pile distributing along foundation ditch to surround around and forms;

(2) large diameter thin wall cylinder pile driving construction

1. the prefabricated pile crown of large diameter thin wall cylinder stake is embedded between interior steel cylinder template and outer steel cylinder template;

2. at the just tube template top mounting clamp device that shakes, be used for fixing dither, dither adjust in place after, interior steel cylinder template and outer steel cylinder template and prefabricated pile crown are pressed in soil to prefabricated pile crown and reach projected depth;

3. the folder that the unclamps template top device that shakes, puts into annular template chamber by prefabricated reinforcing cage, by the concrete pouring gate fluid concrete in outer steel cylinder template, and hoisting steel tube template simultaneously;

4. repeat above-mentioned steps, the next large diameter thin wall cylinder stake of constructing is until required all the going along with sb. to guard him of foundation ditch uses large diameter thin wall cylinder pile driving construction complete;

5. reach after design strength until fender post concrete, remove the assorted soil at bracing of foundation pit stake top, build the capping beam that strengthens each fender post resistance to overturning;

(3) passive area reinforcing pile construction

Passive area reinforcing pile is in large diameter thin wall cylinder stake inner side, and is made up of the cement mixing pile being piled in the soil body;

(4) first floor anchor bolt construction

1. dig down foundation ditch to the following 1m of first floor Soil Anchor Design absolute altitude place;

2. adopt total powerstation to measure setting-out and determine position, Soil Anchor Design hole and anchor hole azimuth according to design drawing, and with it fender post mark;

3. rig is in place, holes in index aperture position;

4. anchor pole is firmly as one man pushed and enters duct, in propelling movement process, must not rotate the body of rod; Adopt pressure piston formula grouting pump to be in the milk to duct, cement paste, in Grouting Pipe pushes hole, is then in the milk, and builds anchoring supporting plate at bolthole road junction and clamp nut is installed;

(5) second layer anchor bolt construction

1. dig down foundation ditch to the following 1m of second layer Soil Anchor Design absolute altitude place;

2. adopt total powerstation to measure setting-out and determine position, Soil Anchor Design hole and anchor hole azimuth according to design drawing, and with it fender post mark;

3. rig is in place, holes in index aperture position;

4. anchor pole is firmly as one man pushed and enters duct, in propelling movement process, must not rotate the body of rod; Adopt pressure piston formula grouting pump to be in the milk to duct, cement paste, in Grouting Pipe pushes hole, is then in the milk; The body of rod reinforcing bar of the anchor pole of reserved certain length is outside duct;

(6) first floor encloses purlin construction

1. body of rod reinforcing bar and first floor outside the second reserved duct of second layer anchor pole are enclosed to purlin reinforcing bar binding;

2. the template that first floor encloses purlin is installed, and concreting.

4. according to the construction method of the large diameter thin wall cylinder stake compound anchor rod-type foundation pit enclosure structure described in claims 1, it is characterized in that: the precast reinforced cage in 3. step by step of construction sequence (2) has been reserved the required hole in anchor pole duct, for anchor pole can be to cylinder, stake destroys minimum in the situation that compound with it through cylinder stake; Pouring concrete in construction sequence (2)-is 3. step pouring segmentation jolt ramming, steel form segmentation lifting.