CN113957887A - Pile-wall integrated construction method of core barrel - Google Patents
Pile-wall integrated construction method of core barrel Download PDFInfo
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- CN113957887A CN113957887A CN202111111287.1A CN202111111287A CN113957887A CN 113957887 A CN113957887 A CN 113957887A CN 202111111287 A CN202111111287 A CN 202111111287A CN 113957887 A CN113957887 A CN 113957887A
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- pile
- continuous wall
- reinforcement cage
- concrete
- steel cylinder
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
- E02D5/38—Concrete or concrete-like piles cast in position ; Apparatus for making same making by use of mould-pipes or other moulds
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D17/00—Excavations; Bordering of excavations; Making embankments
- E02D17/02—Foundation pits
- E02D17/04—Bordering surfacing or stiffening the sides of foundation pits
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/20—Bulkheads or similar walls made of prefabricated parts and concrete, including reinforced concrete, in situ
Abstract
The invention discloses a pile-wall integrated construction method of a core cylinder, which comprises the following steps: (1) sinking a prefabricated steel cylinder carrying a pile body reinforcement cage in the pile hole, wherein the prefabricated steel cylinder is provided with a separation cavity; (2) pouring first concrete into the pile hole from the separation cavity of the prefabricated steel cylinder until the top of the prefabricated steel cylinder, wherein the first concrete and the pile body reinforcement cage form an engineering pile; (3) excavating a continuous groove between the two pile holes, lowering a first reinforcement cage, and then pouring second concrete to form a continuous wall section; (4) and excavating earthwork of the foundation pit, binding a second reinforcement cage and pouring third concrete in an inner post-pouring groove and an outer post-pouring groove formed between two adjacent continuous wall sections synchronously, and connecting the two adjacent continuous wall sections into a whole to finish the construction of the underground continuous wall of the core cylinder. The underground continuous wall is integrally and rigidly connected, and is strong in bending resistance, shearing resistance and corrosion resistance; according to strutting and major structure performance difference, can design respectively, with strong points.
Description
Technical Field
The invention relates to a pile-wall integrated construction method of a core cylinder.
Background
The core barrel is positioned in the central part of the building, is a central core barrel formed by enclosing of an elevator shaft, a stair, a ventilation shaft, a cable shaft, a public washroom and a part of equipment rooms, is poured by reinforced concrete, and forms an outer frame inner barrel structure with a peripheral frame.
The core barrel is of a shear wall structure, if the shear wall is made by a reverse method, a large number of engineering piles must be arranged at the bottom of the shear wall, a large number of shear wall dragging and replacing are needed, the structure is complex, and the safety is poor.
When the reverse construction method is adopted for construction, temporary concrete columns, lattice columns or steel pipe columns are required to be arranged as temporary vertical supporting systems in the construction stage during construction, and temporary systems are removed or permanent components are connected with partial temporary columns to form the stressed shear wall during construction of permanent structure systems. The method has the problems of centralized arrangement of temporary piles, limited vertical support bearing capacity, large workload of temporary pile dismantling, complex connection processing of permanent components and temporary piles, difficult quality control and the like. Under some circumstances, limited by vertical support bearing capacity, superstructure construction loading is limited, influences the engineering project of whole project, leads to this kind of way to have certain limitation.
The other construction method of the core tube shear wall is that the shear wall is completely inserted into the bearing layer, engineering piles are omitted, and the underground continuous wall is directly constructed from the ground, so that the depth of the underground continuous wall is large, the grooving is deep, the construction difficulty is high, the construction period is long, and the construction cost is high.
Disclosure of Invention
In order to solve the problems, the invention provides a pile-wall integrated construction method of a core barrel, which is used for constructing an underground continuous wall and an engineering pile of the core barrel, and the construction method specifically comprises the following steps:
(1) sinking the prefabricated steel cylinder and the pile body reinforcement cage:
constructing pile holes at intervals, wherein the pile holes are circular, and a prefabricated steel cylinder carrying a pile body steel reinforcement cage is sunk in the pile holes, so that the lower end surface of the prefabricated steel cylinder downwards exceeds a first set elevation of the lower end surface of the underground continuous wall, and the top end surface of the pile body steel reinforcement cage upwards does not exceed a second set elevation of the bottom surface of the foundation pit; during specific construction, the top end face of the pile body steel reinforcement cage can be equal to or slightly lower than a second set elevation of the bottom surface of the foundation pit, but the distance between the top end face of the pile body steel reinforcement cage and the second set elevation is not more than 200 mm.
The prefabricated steel cylinder comprises two vertical plates extending along the thickness direction of the underground continuous wall, the two vertical plates are arranged at intervals along the extending direction of the underground continuous wall, two webs are arranged between the two vertical plates, two ends of each web are respectively connected to one vertical plate, the two webs are respectively an inner web and an outer web, and the outer web is positioned on one side of the inner web, which is away from the inner cavity of the core cylinder;
one ends of the two vertical plates exceed the inner web inwards to form an inner flange, and the other ends of the two vertical plates exceed the outer web outwards to form an outer flange; one side of each inner flange, which is far away from the outer flange, is provided with an inner limiting plate, and the two inner limiting plates extend along the extension direction of the underground continuous wall and have opposite extension directions; one side of each outer flange, which is far away from the inner flange, is provided with an outer limiting plate, and the two outer limiting plates extend along the extension direction of the underground continuous wall and have opposite extension directions; the space surrounded by the two vertical plates and the two web plates forms a separate cavity; in the application, the extending directions of the inner limiting plate and the outer limiting plate are both directions from the vertical plate connected with the inner limiting plate to the other end, far away from the vertical plate connected with the inner limiting plate, of the inner limiting plate as a starting point to a terminal point;
the lower end of the prefabricated steel cylinder is inserted into the upper end of the inner cavity of the pile body reinforcement cage, and the prefabricated steel cylinder is fixedly connected to the pile body reinforcement cage, so that the lower end of the prefabricated steel cylinder is in lap joint with the upper end of the pile body reinforcement cage; the lap joint length of the prefabricated steel cylinder and the pile body steel reinforcement cage is 3-5D, and D is the diameter of the pile hole;
and the second distance between the lower end surface of the pile body steel reinforcement cage and the second set elevation of the bottom surface of the foundation pit is the pile length of the engineering pile.
(2) Pile hole filling:
in the pile hole, the area outside the outer web plate is formed into an outer filling area, the area inside the inner web plate is formed into an inner filling area, and the areas outside the two vertical plates are both formed into outer lateral areas;
pouring first concrete into the separation cavity, wherein the first concrete and the pile body reinforcement cage form an engineering pile, the first concrete in the separation cavity upwards reaches the top of the prefabricated steel cylinder, and the first concrete outside the separation cavity upwards does not exceed a first set elevation of the lower end face of the underground continuous wall; filling backfill in the outer filling area and the inner filling area, and filling sand in the two outer lateral areas; filling sand, namely filling sand, wherein the backfill soil and the sand are supported on the first concrete with the separated cavities;
(3) excavating a continuous groove between two pile holes, finishing the excavation of the continuous groove, putting a first reinforcement cage in the continuous groove, pouring second concrete, finishing the construction of a continuous wall section in the continuous groove, and forming the continuous wall section, the first concrete in the separation cavity and the prefabricated steel cylinder into an initial underground continuous wall;
(4) excavating earth of the foundation pit and finishing;
removing an inner flange at the upper part of the bottom surface of the foundation pit, and exposing the inner temporary end surface of the continuous wall section covered by the inner flange; removing an outer flange at the upper part of the bottom surface of the foundation pit, and exposing an outer temporary end surface of the continuous wall section covered by the outer flange;
the groove formed by the two opposite inner side temporary end surfaces and the inner web plate forms an inner side post-pouring groove, and the groove formed by the two opposite outer side temporary end surfaces and the outer web plate forms an outer side post-pouring groove; and cleaning the surfaces of the inner side casting groove and the outer side post casting groove, binding a second reinforcement cage and casting third concrete in the inner side casting groove and the outer side post casting groove respectively, and connecting two adjacent continuous wall sections and webs into a whole to complete the construction of the underground continuous wall of the core tube.
The lap joint of the prefabricated steel cylinder and the pile body reinforcement cage is preferably carried out in a welding mode, the construction is convenient, the strength is good, and other modes can be adopted, such as welding a special connecting piece on the outer side of the prefabricated steel cylinder, connecting the prefabricated steel cylinder and the pile body reinforcement cage to the reinforcement cage in a binding mode or connecting the prefabricated steel cylinder and the pile body reinforcement cage together by bolts.
In order to avoid pouring the second concrete, a large amount of second concrete enters the outer filling area and the inner filling area, subsequent chiseling work is increased, the distance between the inner limiting plate and the inner wall of the pile hole and the distance between the outer limiting plate and the inner wall of the pile hole are smaller than or equal to 5mm, and therefore the overflow amount of the second concrete is reduced while the prefabricated steel cylinder is guaranteed to sink into the pile hole smoothly.
In order to facilitate the removal of the inner flange and the inner limiting plate, and the outer flange and the outer limiting plate, isolation paints are painted on the inner flange and the inner limiting plate, and on the sides of the outer flange and the outer limiting plate, which face the continuous wall section.
In this application, in the work progress earlier in prefabricated steel cylinder and pile body steel reinforcement cage transfer the stake downthehole, and carry out first concrete placement, make first concrete and pile body steel reinforcement cage form the engineering stake, because the connection effect of first concrete, make prefabricated steel cylinder and engineering stake form an organic whole, in the construction of underground continuous wall afterwards, use prefabricated steel cylinder as the construction boundary, the continuous wall section of construction, thereby form initial underground continuous wall, and the pouring work of second steel reinforcement cage and the third concrete in inboard post-cast groove and the outside post-cast groove of back completion back in step when excavating the foundation ditch, accomplish underground continuous wall's construction.
When the first concrete is poured, the first concrete is directly poured to the top of the prefabricated steel cylinder, so that the rigidity of the prefabricated steel cylinder is increased, the weight and the stability of the prefabricated steel cylinder are improved, the connection strength of the first concrete in the prefabricated steel cylinder and the engineering pile can be provided, and weak points are formed during secondary pouring.
Because interior restriction board and outer restriction board all extend along underground continuous wall's extending direction, make interior restriction board and outer restriction board parallel to each other, form a U-shaped groove between riser and the interior restriction board that is connected and the outer restriction board, only need do the adduction slightly to the both ends of first steel reinforcement cage, suitably reduce the thickness of first steel reinforcement cage, can guarantee sinking smoothly of first steel reinforcement cage in the continuous groove, wherein the thickness reduction control of first steel reinforcement cage can at 5-20mm, the construction degree of difficulty has been reduced, the wall body intensity of joint department has been improved. Because the prefabricated steel cylinder is not recycled and is reserved underground and used as a joint component of two continuous wall sections, the construction efficiency can be effectively improved, and the construction period can be shortened. Circular stake hole, current construction technology is comparatively mature, specifically can adopt wet process or dry construction, corresponds specific stake hole excavation technology and no longer gives details.
Because the prefabricated steel cylinder in this application is as a part of underground continuous wall, the joint equipment that prior art adopted is removed to and the joint hoists the tonnage together with the steel reinforcement cage in the continuous groove too big, the too high problem of cost of manufacture.
In this application, too big for avoiding prefabricated steel cylinder structure, the preparation, sink inconveniently, can make prefabricated steel cylinder segmentation, the segmentation sinks to at the in-process that sinks, weld each section again as a whole.
Because the lower end of the prefabricated steel cylinder is connected to the engineering pile, the lateral rigidity is improved, and the stability of the prefabricated steel cylinder is improved.
The prefabricated steel cylinder and the corresponding first concrete are constructed firstly, and then the diaphragm wall section is constructed, so that the difficult problem of joint of the underground diaphragm wall is solved, the connecting parts are prefabricated connecting components, and when the rest underground diaphragm walls are cast in situ, the problems of poor strength of new and old joints and easiness in crack generation are solved. In the excavation process of the foundation pit, the continuous wall section and the prefabricated steel cylinder work together, and the problem of retaining soil and stopping water is solved. Before the third concrete is poured, the inner flange and the outer flange are removed, so that the third concrete and the diaphragm wall section form an integral structure, the construction quality is good, and the problem that the underground diaphragm wall joint is easy to leak is solved. The underground continuous wall is integrally and rigidly connected, and has strong bending resistance, shearing resistance and corrosion resistance; according to strutting and major structure performance difference, can design respectively, with strong points.
And sand is filled in the inner filling area and the outer filling area so as to increase the weight of the prefabricated steel cylinder, improve the stability of the prefabricated steel cylinder and reduce the amount of the second concrete entering the inner filling area and the outer filling area. And the two outer lateral areas are filled with sand, so that the collapse of the pile hole is avoided.
The application is particularly suitable for the construction of core barrels with underground depths of between 10 and 20 meters.
Further, in order to prevent the first concrete from exceeding the bottom surface of the foundation pit upwards through a gap between the outer wall of the prefabricated steel cylinder and the pile hole and increase subsequent chiseling work, and to prevent the first concrete from exceeding a first set elevation of the lower end surface of the underground continuous wall upwards through a gap between the outer wall of the prefabricated steel cylinder and the pile hole and causing difficulty in excavating the continuous groove, a mudguard is arranged on the outer side of the lower end part of the prefabricated steel cylinder; the lower surface of the mudguard does not exceed the first set elevation of the lower end surface of the underground continuous wall. The outer peripheral surface of the fender is circular to be matched with the shape of the pile hole, the distance between the outer peripheral surface of the fender and the pile hole is smaller than or equal to 5mm, the fender can be guaranteed to smoothly sink along the pile hole, and meanwhile a large amount of first concrete can be prevented from exceeding the fender upwards. The fender is located the upside of pile body steel reinforcement cage, and the distance between fender and the upper end face of pile body steel reinforcement cage is less than or equal to 200mm, and the fender can support on the up end of pile body steel reinforcement cage promptly, perhaps has the distance that is less than or equal to 200mm between fender and the pile body steel reinforcement cage.
The lower surface of the fender does not exceed the first set elevation of the lower end face of the underground continuous wall upwards, namely the lower surface of the fender is flush with the first set elevation of the lower end face of the underground continuous wall or downwards exceeds the first set elevation of the lower end face of the underground continuous wall, and when the lower surface of the fender downwards exceeds the lower end face of the underground continuous wall, the distance between the lower surface of the fender and the first set elevation is less than or equal to 200mm, so that the pile holes and the pile body reinforcement cage are fully utilized to form the engineering pile. Because the lower end surface of the continuous wall at least reaches the second set elevation of the bottom surface of the foundation pit downwards, the lower surface of the mudguard does not exceed the second set elevation of the bottom surface of the foundation pit upwards.
Because the core barrel has a certain distance with the edge of the foundation pit, the inner cavity and the outer side of the core barrel are synchronously excavated in the excavation process of the foundation pit, and therefore the second reinforcement cage and the third concrete can be synchronously constructed in the inner post-cast groove and the outer post-cast groove in the inner part and the outer part of the core barrel.
Further, before the third concrete is poured, the first reinforcement cage in the area covered by the outer temporary end face and the inner temporary end face is chiseled out, and the second reinforcement cage is connected to the first reinforcement cage.
After being connected to first steel reinforcement cage with the second steel reinforcement cage on, can avoid because the gap that the concrete shrink produced, avoid outside moisture to enter into foundation ditch and underground construction through these gaps in, guaranteed underground continuous wall's stagnant water performance.
Further, before the third concrete is poured, the second reinforcement cage is welded to the inner web and the outer web respectively. This design makes second steel reinforcement cage and prefabricated steel cylinder form a whole, avoids producing the crack between third concrete and the prefabricated steel cylinder, guarantees the bulk strength of underground continuous wall, avoids outside water to permeate into in foundation ditch or the underground building along these cracks.
Specifically, the surface of the inner limiting plate facing the outer side of the core tube coincides with the inner side surface of the underground continuous wall, and the surface of the outer limiting plate facing the inner side of the core tube coincides with the outer side surface of the underground continuous wall.
The design ensures that the clear distance between the inner limiting plate and the outer limiting plate is the same as the width of the continuous groove, the two ends of the first steel reinforcement cage do not need to reduce the width, or only need to slightly retract, the thickness of the steel reinforcement cage is properly reduced, the reduction value of the thickness of the steel reinforcement cage is controlled within 5-20mm, in the prior art, under the condition that no end channel steel is arranged, in order to be suitable for a pre-sunk connector, the thickness of the two ends of the steel reinforcement cage is generally required to be reduced by 30-50%, taking an underground continuous wall with the thickness of 800mm as an example, the thickness of the two ends of the steel reinforcement cage needs to be reduced by 240-400mm, the thickness of the two ends of the steel reinforcement cage is greatly reduced, the uniformity of the strength of the underground continuous wall is poor, and cracks are easily generated in a connector area. Because the clear distance between the inner vertical plate and the outer vertical plate is the same as the width of the continuous groove, the width and the quality of the cast-in-place width of the continuous wall section are ensured.
Specifically, in order to ensure the water stopping effect and avoid the phenomenon of groundwater streaming, the length of the inner limiting plate is 0.5-1.0 meter, and the length of the outer limiting plate is 0.5-1.0 meter. The horizontal rigidity in the joint area has still been guaranteed in this design, when having avoided adopting H shaped steel or channel-section steel, the drawback of the headroom that needs to reserve the main muscle protective layer has prevented the production of streaming when second concrete placement.
The distance between the outer walls of the two vertical plates of the same prefabricated steel cylinder is 0.5-0.8 m, and the length of the continuous wall section is 2.0-6.0 m.
The outer walls of the two vertical plates are opposite side walls, and the prefabricated steel cylinder has enough weight and strength in the distance range under the condition of carrying the first concrete, so that the stability of the prefabricated steel cylinder can be ensured in the subsequent continuous groove excavation and continuous wall section pouring process, the deflection phenomenon is avoided, and the quality of the underground continuous wall and the flatness of the outer surface are prevented from being influenced.
Furthermore, in the thickness direction of the underground continuous wall, the width of the inner flange is 10-20% of the thickness of the underground continuous wall, and the width of the outer flange is 10-20% of the thickness of the underground continuous wall.
This design can make the third concrete of pouring at last have furthest's width under the prerequisite of guaranteeing that prefabricated steel cylinder has sufficient weight to improve the area of being connected between third concrete and the diaphragm wall section, improve joint strength, thereby improve the homogeneity of each regional intensity of underground continuous wall.
Further, in order to ensure the safety of construction, when the strength of the first concrete reaches 50% of the designed strength, the continuous groove is excavated; when the strength of the first concrete reaches 70% of the first design strength and the strength of the second concrete reaches 70% of the second design strength, constructing a main structure laminate on the top of the initial underground continuous wall, then excavating a foundation pit, and simultaneously constructing an above-ground main structure; in the vertical direction, the orthographic projection of the overground main body structure completely covers the core barrel;
and when the strength of the main structure layer plate reaches 70% of the third design strength, synchronously excavating the foundation pit and constructing the ground main structure.
When the strength of the first concrete reaches 50% of the design strength of the first concrete, the first concrete has enough strength, and because in the excavation process of the continuous groove, the excavating machinery can not touch the first concrete, and only can touch the prefabricated steel cylinder occasionally, the safety problem can not be caused, so that the strength of the first concrete reaches 50% of the design strength of the first concrete, the construction progress is mainly accelerated, the continuous groove can be excavated without waiting for the first concrete to reach higher strength, and the construction efficiency can be effectively improved.
When the main structure laminated plate is constructed, a large amount of load can be loaded on the prefabricated steel cylinder and the continuous wall section in sequence, so that the construction of the main structure laminated plate can be carried out only after the second concrete reaches 70% of the second design strength, and because the pouring time of the second concrete is later than that of the first concrete, when the second concrete reaches 70% of the second design strength, the first concrete generally reaches 70% of the first design strength, but in order to ensure safety, the strength of the first concrete and the strength of the second concrete need to be checked at the same time.
Further, in order to improve the integrity of the underground structure, in the step (4), excavating earthwork in the foundation pit layer by layer, dismantling the inner flange and the outer flange section by section from top to bottom, synchronously binding a second reinforcement cage section by section and pouring third concrete until the excavation of the earthwork in the foundation pit is finished, then pouring a bottom plate, and after the pouring of the bottom plate is finished, sequentially manufacturing each middle plate in the core barrel from bottom to top; the steel bar net in the bottom plate and each middle plate is connected with the first steel bar cage and the second steel bar cage in the underground continuous wall. The design can improve the anti-floating performance of the underground building, and the stable connection between the underground structure and the underground continuous wall, so that the safety of the underground building is improved.
Drawings
Fig. 1 is a schematic flow chart diagram according to an embodiment of the present application.
Fig. 2 is a top view of a core barrel.
Fig. 3 is a schematic structural diagram of a prefabricated steel cylinder.
Fig. 4 is an enlarged view of a portion a in fig. 1.
Fig. 5 is an enlarged view of a portion B in fig. 1.
Fig. 6 is a view in the direction C-C of fig. 1.
Fig. 7 is a connection structure diagram of the prefabricated steel cylinder and the pile body reinforcement cage.
Detailed Description
Referring to fig. 2, in the present embodiment, the underground continuous wall 91 and the engineering pile 69 for constructing the core tube 90 are shown, the core tube 90 in the present embodiment has a rectangular cross section, and the underground continuous wall 91 is a shear wall structure.
Referring first to fig. 1, in fig. 1, an arrow V indicates a thickness direction of the underground diaphragm wall, and an arrow L indicates an extending direction of the underground diaphragm wall.
The following description first describes the structure of the prefabricated steel cylinder 10 and the pile reinforcement cage 60, please refer to fig. 3 and 7, and as viewed in the vertical direction, the prefabricated steel cylinder 10 includes two vertical plates extending along the thickness direction of the underground continuous wall, the two vertical plates are respectively the first vertical plate 13 and the second vertical plate 14, the extending directions of the two vertical plates of the underground continuous wall are spaced and parallel to each other, two webs are disposed between the two vertical plates, two ends of the two webs are equally connected to one vertical plate, the two webs are respectively the inner web 12 and the outer web 11, and when the prefabricated steel cylinder 10 is sunk underground, the outer web 11 is located on the side of the inner web 12 away from the inner cavity 96 of the core cylinder.
One end of each vertical plate inwards exceeds the inner web 12 to form an inner flange 106, and the other end of each vertical plate outwards exceeds the outer web 11 to form an outer flange 107. Each side of the inner flange 106 facing away from the outer flange 107 is provided with an inner limiting plate 108, and the two inner limiting plates 108 extend along the extension direction of the underground continuous wall and have opposite extension directions. One side of each outer flange 107, which faces away from the inner flange, is provided with an outer limiting plate 109, and the two outer limiting plates 109 extend along the extending direction of the underground continuous wall and have opposite extending directions. The space enclosed by the two vertical plates and the two web plates forms a compartment 102.
The extending directions of the inner limiting plates are all directions taking the vertical plate connected with the inner limiting plate as a starting point and taking the other end of the inner limiting plate far away from the vertical plate connected with the inner limiting plate as an end point, and the extending directions of the outer limiting plates are all directions taking the vertical plate connected with the outer limiting plate as a starting point and taking the other end of the outer limiting plate far away from the vertical plate connected with the outer limiting plate as an end point.
In this embodiment, in the thickness direction of the underground continuous wall, the first width SA of the inner flange 106 is 15% of the thickness SD of the underground continuous wall, and the second width SB of the outer flange 107 is 15% of the thickness SD of the underground continuous wall. It is understood that in other embodiments, the first width SA of the inner flange 106 may also be 10%, 12%, 16%, 18%, or 20% of the thickness SD of the underground diaphragm wall, and the second width SB of the outer flange 107 may also be 10%, 12%, 16%, 18%, or 20% of the thickness SD of the underground diaphragm wall. In this embodiment, the first width SA of the inner flange 106 and the second width SB of the outer flange 107 are the same, and it is understood that in other embodiments, the first width SA of the inner flange 106 may be different from the second width SB of the outer flange 107, for example, the first width SA of the inner flange 106 may be 12% of the thickness SD of the underground continuous wall, and the second width SB of the outer flange 107 may be 20% of the thickness SD of the underground continuous wall.
The first length SE of the inner limiting plate 108 is 0.8 m and the second length SF of the outer limiting plate 109 is 0.8 m. It is understood that in other embodiments, the first length SE of the inner limiting plate 108 may also be 0.5 meter, 0.8 meter, or 1 meter, and the second length SF of the outer limiting plate 109 may also be 0.5 meter, 0.8 meter, or 1 meter. In this embodiment, the first length SE of the inner limiting plate 108 and the second length SF of the outer limiting plate 109 are the same, but it is understood that in other embodiments, the two may also be different, for example, the first length SE of the inner limiting plate 108 is 0.6 meter and the second length SF of the outer limiting plate 109 is 1 meter.
In the same prefabricated steel cylinder 10, the first distance W between the first outer wall 135 of the first upright plate 13 away from the second upright plate 14 and the second outer wall 145 of the second upright plate 14 away from the first upright plate 13 is 0.6 m, that is, the first distance between the outer walls of the two upright plates of the same prefabricated steel cylinder is 0.6 m, and it can be understood that, in other embodiments, the first distance between the outer walls of the two upright plates of the same prefabricated steel cylinder may also be 0.5 m, 0.7 m, or 0.8 m.
The lower end of the prefabricated steel cylinder 10 is inserted into the upper end of the inner cavity of the pile body steel reinforcement cage 60, the prefabricated steel cylinder is fixedly connected to the pile body steel reinforcement cage, the pile body steel reinforcement cage 60 comprises longitudinal reinforcements 61 arranged along the circumferential direction and stirrups 62 wound on the longitudinal reinforcements 61, in the embodiment, the prefabricated steel cylinder 10 is welded on the stirrups 62 of the pile body steel reinforcement cage, the lower end of the prefabricated steel cylinder 10 is in lap joint with the upper end of the pile body steel reinforcement cage 60, the lap joint length Q is 4 times of the diameter D of the pile hole, and according to different load requirements, the lap joint length can be 3 times, 3.5 times, 4.5 times or 5 times of the diameter of the pile hole.
And a mudguard 18 is arranged on the outer side of the lower end part of the prefabricated steel cylinder 10, the periphery of the mudguard is circular, and the mudguard is pressed on the upper end surface of the pile body steel reinforcement cage. It will be appreciated that in other embodiments, the mudguard 18 may be spaced from the upper end surface of the pile reinforcement cage, but the spacing is not too large, and is preferably within 200mm, so as to make full use of the pile reinforcement cage to form the engineering pile.
The following description is made of a pile-wall integrated construction method of a core tube, referring to fig. 1, the construction method includes the following steps:
(1) sinking the prefabricated steel cylinder 10 and the pile body reinforcement cage 60:
referring to step (a) of fig. 1, pile holes 20 are formed at intervals by using a long auger, the pile holes 20 are formed in a circular shape, and then a prefabricated steel cylinder 10 carrying a pile reinforcement cage 60 is sunk into each pile hole 20 such that the lower end surface of the prefabricated steel cylinder is lowered to a first set elevation above the lower end surface 110 of the underground diaphragm wall. With the inner web 12 on the side facing the core barrel cavity and the outer web 11 on the side of the inner web facing away from the core barrel cavity. The two vertical plates extend along the thickness direction of the underground continuous wall.
The distance between the inner limiting plate and the inner wall of the pile hole and the distance between the outer limiting plate and the inner wall of the pile hole are both less than or equal to 5mm, the lower surface of the fender is flush with the first set elevation of the lower end face of the underground continuous wall, the distance between the outer peripheral surface of the fender and the inner wall of the pile hole is less than or equal to 5mm, and the lower surface of the fender does not exceed the first set elevation of the lower end face of the underground continuous wall upwards. It will be appreciated that in another embodiment, the lower surface of the fender extends downwardly beyond the first set elevation of the lower end surface of the underground diaphragm wall, but the distance between the lower surface of the fender and the first set elevation is preferably controlled to be within 200mm, for example 50mm, 100mm or 200mm, to accommodate construction errors.
In this embodiment, the top end surface of the pile reinforcement cage and the second set elevation of the bottom surface of the foundation pit are equal in height, and it can be understood that in other embodiments, the top end surface of the pile reinforcement cage may be slightly lower than the second set elevation of the bottom surface of the foundation pit, and the distance between the top end surface of the pile reinforcement cage and the second set elevation is controlled within 200mm, for example, 30mm, 80mm, 130mm, or 200mm, so as to ensure that the engineering pile can be formed to the maximum extent in the height direction. Namely, the top end surface of the pile body reinforcement cage does not exceed the second set elevation of the bottom surface of the foundation pit upwards.
And the second distance G between the lower end surface of the pile body steel reinforcement cage and the second set elevation of the bottom surface of the foundation pit is the pile length of the engineering pile.
(2) Pile hole filling:
referring to fig. 3, 4 and (b) of fig. 1, in the pile hole 20, the area outside the outer web 11 is formed as an outer filling area 103, the area inside the inner web 12 is formed as an inner filling area 101, and the areas outside both the two vertical plates are formed as outer lateral areas 105;
pouring first concrete 21 into the separation cavity 102, wherein the first concrete 21 and the pile body reinforcement cage 60 form an engineering pile 69, the first concrete in the separation cavity upwards reaches the top of the prefabricated steel cylinder 10, and the first concrete outside the separation cavity upwards does not exceed a first set elevation of the lower end face of the underground continuous wall due to the obstruction of the mud guard 18. The outer filling zone 103 and the inner filling zone 101 are filled with backfill 22 and the two outer lateral zones 105 with sand, i.e. the two outer lateral zones 105 with sand 23, both backfill and sand being supported on the mudguards.
(3) Referring to (c) and (d) of fig. 1, when the strength of the first concrete reaches 50% of the designed strength, the continuous groove 30 is excavated between the two pile holes 20, the first reinforcement cage 31 is lowered into the continuous groove 30, the second concrete 32 is poured, and the continuous wall section 39 in the continuous groove is constructed, and the continuous wall section, the first concrete in the compartment and the prefabricated steel cylinder form an initial underground continuous wall. In this embodiment, the fourth length M of the continuous wall section 39 is 4.6-4.9 meters, it is understood that in other embodiments, the fourth length of the continuous wall section 39 may also be 2 meters, 3 meters, 4 meters or 6 meters, and since the cross section of the core cylinder may be square or rectangular, in the same embodiment, the fourth length of the continuous wall sections may be the same or different, but in the same embodiment, the difference of the fourth length of each continuous wall section is preferably not more than 0.5 meter.
(4) Referring to (e) and (f) of fig. 1, after the strength of the first concrete reaches 70% of the first design strength and the strength of the second concrete reaches 70% of the second design strength, a main structural slab is constructed on the top of the initial underground continuous wall, and after the strength of the main structural slab reaches 70% of the third design strength, earth excavation of the foundation pit 100 is performed and completed. And in the excavation process of the foundation pit, the inner cavity and the outer side of the core barrel are synchronously excavated.
And simultaneously carrying out foundation pit earthwork excavation and construction of the main structure on the ground synchronously. In this embodiment, the orthographic projection of the above-ground body structure in the vertical direction completely covers the core barrel.
When the foundation pit is excavated, earthwork is excavated layer by layer, a second reinforcement cage is bound in a segmenting mode from top to bottom, third concrete is poured until excavation of the earthwork in the foundation pit is completed, then a bottom plate is poured, and after pouring of the bottom plate is completed, middle plates in the core barrel are made sequentially from bottom to top. The steel bar net in the bottom plate and each middle plate is connected with the first steel bar cage and the second steel bar cage in the underground continuous wall.
In this embodiment, with the excavation of earthwork in the foundation pit layer by layer, the inner flange 106 and the inner limiting plate 108 connected to the inner flange are removed section by section from top to bottom, and the inner temporary end surface 311 of the continuous wall section covered by the inner flange is exposed; the outer flange 107 and the outer limiting plate 109 connected to the outer flange are removed to expose the outer temporary end face 312 of the continuous wall section covered by the outer flange. The recess formed by the two opposing inner temporary end faces and the inner web is formed as an inner post-cast channel 48 and the recess formed by the two opposing outer temporary end faces and the outer web is formed as an outer post-cast channel 49. And then cleaning the surfaces 49 of the inner casting groove 48 and the outer post-casting groove, binding a second reinforcement cage 42 in the inner casting groove and the outer post-casting groove respectively, and casting third concrete 43 to form a post-casting section 41. And when the earthwork in the foundation pit is excavated, the post-pouring section is constructed, and the post-pouring section connects two adjacent continuous wall sections and the web plate into a whole to complete the construction of the underground continuous wall of the core cylinder.
In this embodiment, the inner flange 106 and the inner restraining plate 108, and the outer flange 107 and the outer restraining plate 109 are removed simultaneously, and it is understood that at least one of the inner restraining plate 108 and the outer restraining plate 109 may be left without affecting construction and other structures.
In this embodiment, in order to enhance the connection strength between the post-cast section and the steel cylinder and the continuous wall section, before the third concrete is poured, the first reinforcement cage in the area covered by the outer temporary end face and the inner temporary end face is chiseled out, and the second reinforcement cage is connected to the first reinforcement cage; and welding a second reinforcement cage to the inner web and the outer web, respectively.
In order to facilitate the removal of the inner flange 106 and the inner limiting plate 108, and the outer flange 107 and the outer limiting plate 109, the sides of the inner flange 106 and the inner limiting plate 108, and the outer flange 107 and the outer limiting plate 109 facing the continuous wall section are painted with an insulating paint.
In this embodiment, the surface of the inner limiting plate 108 facing the outside of the core tube coincides with the inner surface of the underground diaphragm wall, and the surface of the outer limiting plate facing the inside of the core tube coincides with the outer surface of the underground diaphragm wall.
While the present embodiment employs dry excavation of pile holes, it is understood that in another embodiment, wet techniques such as slurry retaining walls may also be employed to excavate the pile holes.
Claims (10)
1. The pile-wall integrated construction method of the core barrel is used for constructing the underground continuous wall and the engineering pile of the core barrel, and is characterized by comprising the following steps:
(1) sinking the prefabricated steel cylinder and the pile body reinforcement cage:
constructing pile holes at intervals, wherein the pile holes are circular, and a prefabricated steel cylinder carrying a pile body steel reinforcement cage is sunk in the pile holes, so that the lower end surface of the prefabricated steel cylinder downwards exceeds a first set elevation of the lower end surface of the underground continuous wall, and the top end surface of the pile body steel reinforcement cage upwards does not exceed a second set elevation of the bottom surface of the foundation pit;
the prefabricated steel cylinder comprises two vertical plates extending along the thickness direction of the underground continuous wall, the two vertical plates are arranged at intervals along the extending direction of the underground continuous wall, two webs are arranged between the two vertical plates, two ends of each web are respectively connected to one vertical plate, the two webs are respectively an inner web and an outer web, and the outer web is positioned on one side of the inner web, which is away from the inner cavity of the core cylinder;
one ends of the two vertical plates exceed the inner web inwards to form an inner flange, and the other ends of the two vertical plates exceed the outer web outwards to form an outer flange; one side of each inner flange, which is far away from the outer flange, is provided with an inner limiting plate, and the two inner limiting plates extend along the extension direction of the underground continuous wall and have opposite extension directions; one side of each outer flange, which is far away from the inner flange, is provided with an outer limiting plate, and the two outer limiting plates extend along the extension direction of the underground continuous wall and have opposite extension directions; the space surrounded by the two vertical plates and the two web plates forms a separate cavity;
the lower end of the prefabricated steel cylinder is inserted into the upper end of the inner cavity of the pile body reinforcement cage, and the prefabricated steel cylinder is fixedly connected to the pile body reinforcement cage, so that the lower end of the prefabricated steel cylinder is in lap joint with the upper end of the pile body reinforcement cage;
(2) pile hole filling:
in the pile hole, the area outside the outer web plate is formed into an outer filling area, the area inside the inner web plate is formed into an inner filling area, and the areas outside the two vertical plates are both formed into outer lateral areas;
pouring first concrete into the separation cavity, wherein the first concrete and the pile body reinforcement cage form an engineering pile, the first concrete in the separation cavity upwards reaches the top of the prefabricated steel cylinder, and the first concrete outside the separation cavity upwards does not exceed a first set elevation of the lower end face of the underground continuous wall; filling backfill in the outer filling area and the inner filling area, and filling sand in the two outer lateral areas;
(3) excavating a continuous groove between two pile holes, finishing the excavation of the continuous groove, putting a first reinforcement cage in the continuous groove, pouring second concrete, finishing the construction of a continuous wall section in the continuous groove, and forming the continuous wall section, the first concrete in the separation cavity and the prefabricated steel cylinder into an initial underground continuous wall;
(4) excavating earth of the foundation pit and finishing;
removing an inner flange at the upper part of the bottom surface of the foundation pit, and exposing the inner temporary end surface of the continuous wall section covered by the inner flange; removing an outer flange at the upper part of the bottom surface of the foundation pit, and exposing an outer temporary end surface of the continuous wall section covered by the outer flange;
the groove formed by the two opposite inner side temporary end surfaces and the inner web plate forms an inner side post-pouring groove, and the groove formed by the two opposite outer side temporary end surfaces and the outer web plate forms an outer side post-pouring groove; and cleaning the surfaces of the inner side casting groove and the outer side post casting groove, binding a second reinforcement cage and casting third concrete in the inner side casting groove and the outer side post casting groove respectively, and connecting two adjacent continuous wall sections and webs into a whole to complete the construction of the underground continuous wall of the core tube.
2. The pile-wall integrated construction method according to claim 1,
a mudguard is arranged on the outer side of the lower end part of the prefabricated steel cylinder; the lower surface of the mudguard does not exceed the first set elevation of the lower end surface of the underground continuous wall.
3. The pile-wall integrated construction method according to claim 1,
and before pouring the third concrete, chiseling out the first reinforcement cage in the area covered by the outer temporary end face and the inner temporary end face, and connecting the second reinforcement cage to the first reinforcement cage.
4. The pile-wall integrated construction method according to claim 1,
and before pouring the third concrete, respectively welding a second reinforcement cage to the inner web plate and the outer web plate.
5. The pile-wall integrated construction method according to claim 1,
the surface of the inner limiting plate facing the outer side of the core tube coincides with the inner side face of the underground continuous wall, and the surface of the outer limiting plate facing the inner side of the core tube coincides with the outer side face of the underground continuous wall.
6. The pile-wall integrated construction method according to claim 1,
the length of the inner limiting plate is 0.5-1.0 m, and the length of the outer limiting plate is 0.5-1.0 m.
7. The pile-wall integrated construction method according to claim 1,
the distance between the outer walls of the two vertical plates of the same prefabricated steel cylinder is 0.5-0.8 m, and the length of the continuous wall section is 2.0-6.0 m.
8. The pile-wall integrated construction method according to claim 1, wherein in the thickness direction of the underground continuous wall, the width of the inner flange is 10-20% of the thickness of the underground continuous wall, and the width of the outer flange is 10-20% of the thickness of the underground continuous wall.
9. The pile-wall integrated construction method according to claim 1,
when the strength of the first concrete reaches 50% of the designed strength, excavating the continuous groove;
when the strength of the first concrete reaches 70% of the first design strength and the strength of the second concrete reaches 70% of the second design strength, constructing a main structure laminate on the top of the initial underground continuous wall, then excavating a foundation pit, and simultaneously constructing an above-ground main structure; in the vertical direction, the orthographic projection of the overground main body structure completely covers the core barrel;
and when the strength of the main structure layer plate reaches 70% of the third design strength, synchronously excavating the foundation pit and constructing the ground main structure.
10. The pile-wall integrated construction method according to claim 1,
in the step (4), excavating earthwork in the foundation pit layer by layer, dismantling the inner flange and the outer flange section by section from top to bottom, synchronously binding a second reinforcement cage section by section and pouring third concrete until the excavation of the earthwork in the foundation pit is finished, then pouring a bottom plate, and after the pouring of the bottom plate is finished, sequentially manufacturing each middle plate in the core barrel from bottom to top;
the steel bar net in the bottom plate and each middle plate is connected with the first steel bar cage and the second steel bar cage in the underground continuous wall.
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