CN115288154B - Efficient construction method of annular ultra-deep permanent foundation pit supporting structure - Google Patents
Efficient construction method of annular ultra-deep permanent foundation pit supporting structure Download PDFInfo
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- 238000010276 construction Methods 0.000 title claims abstract description 82
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 21
- 238000013461 design Methods 0.000 claims abstract description 20
- 238000009412 basement excavation Methods 0.000 claims abstract description 18
- 238000000034 method Methods 0.000 claims abstract description 16
- 239000002689 soil Substances 0.000 claims description 25
- 239000004567 concrete Substances 0.000 claims description 10
- 239000011150 reinforced concrete Substances 0.000 claims description 9
- 229910000831 Steel Inorganic materials 0.000 claims description 7
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- 238000005452 bending Methods 0.000 description 7
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- 230000002829 reductive effect Effects 0.000 description 3
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- 238000004364 calculation method Methods 0.000 description 2
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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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention provides a high-efficiency construction method of a circular ultra-deep permanent foundation pit supporting structure, which provides a method for supporting a lining wall and a continuous wall by adding a pile integrated inner ring supporting structure, solves the engineering technical problems that a construction joint between the lining wall and the lining wall has larger tensile stress, and the construction joint between the lining wall and the continuous wall has complex stress so as to frequently crack and leak water, improves the integral supporting capacity and durability of the permanent supporting structure, and meets the service requirement of 50-100 years; on the other hand, the technical route and the technical bottleneck of the original design and construction method are broken through, and a high-efficiency construction method of multi-layer primary excavation and reverse-forward combination is provided for constructing the annular ultra-deep permanent foundation pit and the lining wall, namely, at least two layers of earthwork are excavated downwards continuously, the height of each layer of earthwork is at least 2.5m, then at least two layers of earthwork are separated from each other, and the lining wall is constructed in a layer-by-layer and high-efficiency forward mode, so that the construction is repeated until the foundation pit bottom is constructed, and the working efficiency is greatly improved.
Description
Technical Field
The invention belongs to the technical field of foundation pit design and construction, and particularly relates to a high-efficiency construction method of a circular ultra-deep permanent foundation pit supporting structure.
Background
The foundation pit supporting engineering is used for supporting, reinforcing and protecting the side wall of the foundation pit and the surrounding environment of the foundation pit in order to ensure the safety of the underground structure construction and the surrounding environment of the foundation pit. The continuous wall supporting structure and the lining wall structure are adopted for the ultra-deep foundation pit, namely a wall supporting structure, and the traditional annular ultra-deep foundation pit supporting structure has the following defects:
1. the pure theoretical calculation analysis method of the continuous wall supporting structure of the annular ultra-deep foundation pit converts the horizontal thrust of soil into the hoop pressure of the continuous wall and the lining wall of the annular ultra-deep permanent foundation pit, so that no inner support is arranged in the annular ultra-deep foundation pit. However, the horizontal water and soil pressure born by the annular ultra-deep foundation pit is not uniform, when various adverse conditions such as nonuniform surrounding soil layer distribution, nonuniform earth excavation, nonuniform surrounding pile loading, nonuniform soil layer excavation depth or dissymmetry, other underground spaces around the soil excavation depth are met, the stress of the annular ultra-deep permanent foundation pit continuous wall supporting structure is nonuniform, even the condition of drifting of the annular ultra-deep permanent foundation pit occurs, and the supporting structure of the annular ultra-deep permanent foundation pit is subjected to not only circumferential pressure, but also composite stress such as bending shear. If no targeted measures are taken, new design, construction and construction methods are provided, and only the circumferential pressure is considered according to the traditional calculation and analysis method of pure theory, so that the safety risk is very easy to generate.
2. Because the thickness of the lining wall of the annular ultra-deep foundation pit continuous wall is thicker and is generally 1 to 3.0 meters, the traditional design and construction method is to design and construct the lining wall with the height of 3 meters in a downward layered reverse manner each time, the traditional technology hangs the lining wall with the thickness on the side surface of the continuous wall, and the lining wall and the construction joint of the continuous wall supporting structure bear larger bending shear stress. Meanwhile, as the lining walls of the upper layer are hung under the lining walls layer by 3m high, the construction joint between the lining walls is also subjected to larger tensile stress, the downward load of each square meter of the lining wall in each layer is 75kPa (3 m high), and the downward load of each square meter of the lining wall in 10 layers to 15 layers is 750kPa to 1125kPa. The connection between each lining wall and the continuous wall and the connection between the upper lining wall and the lower lining wall can generate great complex stress at the construction joint in the construction process to cause cracking and a large amount of water leakage, which is very adverse to the safety and the use function of the ultra-deep permanent underground structure and seriously affects the safety, the durability and the use function of the underground structure, and is one of the main reasons for the existence of a large amount of water leakage of the similar underground structure at present.
3. Because the traditional deep foundation pit supporting structure is a temporary supporting structure, the service life of the ultra-deep foundation pit supporting structure such as a bridge circular anchor ingot is 1.5-2 years, when the casting of anchor ingot concrete in the circular anchor ingot ultra-deep foundation pit is completed, the functions and actions of the circular anchor ingot ultra-deep foundation pit supporting structure are completed, the connection between the lining wall and the continuous wall in each layer and the connection between the upper lining wall and the lower lining wall can generate great complex stress at a construction joint, so that a great amount of leakage water occurs, and the service life requirement of the bridge circular anchor ingot deep foundation pit supporting structure is not influenced for 1.5-2 years, but the requirement of the permanent ultra-deep foundation pit (note: the service depth of the foundation pit = the excavation depth of the foundation pit-the thickness of the bottom plate, namely, the service depth of the foundation pit differs from the excavation depth of the foundation pit by the thickness of the bottom plate, namely, the foundation pit is 45m, the bottom plate thickness is 4m, the service depth of the foundation pit is 41m, namely, the permanent ultra-deep foundation pit) supporting structure is not influenced by the service life requirement of the 50-100 years. Meanwhile, the temporary deep foundation pit supporting structure is abandoned and permanently placed underground after the construction of the underground main structure is finished, and certain temporary supporting structures also need to be removed, so that larger resource waste is caused, and the problems of high construction risk, long construction period, environmental pollution and the like exist.
And because the ultra-deep foundation pit such as the annular anchor ingot is a temporary supporting structure with the service life of 1.5-2 years, and the service life of the permanent ultra-deep foundation pit supporting structure is 50-100 years, the construction difficulty and the requirement are far higher than those of the temporary annular ultra-deep foundation pit supporting structure. Therefore, the design and construction method of the temporary annular ultra-deep foundation pit supporting structure is not suitable for the construction of the annular ultra-deep permanent foundation pit supporting structure.
4. The traditional annular ultra-deep foundation pit supporting structure design and construction method comprises the steps of firstly constructing a continuous wall with a certain thickness, then excavating earthwork downwards layer by taking the height of 3m as one layer, constructing the lining wall by adopting a method of layer by layer reverse operation by taking the height of 3m, namely excavating earthwork downwards in layers (rings), wherein the height of each layer (ring) is 3 meters, and sequentially hanging the construction lining wall downwards layer by layer, circularly and reversely operating the construction lining wall downwards layer by layer according to the flow of earth excavation, paving lining wall steel bars, supporting lining wall templates and pouring lining wall concrete until the construction is carried out to the bottom of an underground structure. According to the different size and depth of the foundation pit, the construction time of each layer (ring) is generally 20-30 days, the circular ultra-deep foundation pit with the depth of 45m underground is divided into 15 layers (rings) for construction, 300-450 days are needed, meanwhile, the concrete curing time (such as 10 days/layer) must be considered, the next layer of earthwork can be continuously excavated downwards when the concrete strength reaches 80% of the design strength, the total construction time can reach 450-600 days, and the efficiency is very low. For a long time, the design and construction bottleneck of the annular ultra-deep foundation pit which is constructed by taking 3m layers (rings) downwards layer by layer (rings) as the lining wall are not broken through all the time, so that the annular ultra-deep foundation pit often needs two construction periods in the main flood season of the Yangtze river, and the safety of the Yangtze river levee is affected.
Therefore, there is a need to develop an efficient construction method for an annular ultra-deep permanent foundation pit supporting structure to solve the above-mentioned problems of the prior art.
Disclosure of Invention
The invention mainly aims to solve 4 great engineering technical problems in the background technology, and provides a method for efficiently constructing a circular ultra-deep permanent foundation pit, wherein a pile column one-body inner ring bracing structure is added to solve the engineering technical problems that a construction joint between a lining wall and a lining wall has larger tensile stress, and a construction joint between the lining wall and a continuous wall has complex stress so as to frequently crack and leak water, and the whole supporting capacity and durability of a permanent supporting structure are improved, so that the service requirement of 50-100 years is met; on the other hand, the technical route and the technical bottleneck of the traditional design and construction are broken through, and the efficient construction method of multi-layer primary excavation and reverse-forward combination is provided for constructing the annular ultra-deep permanent foundation pit and the lining wall, so that the working efficiency is greatly improved.
The invention is realized in the following way:
the invention provides a high-efficiency construction method of a circular ultra-deep permanent foundation pit supporting structure, which comprises the following steps:
s1: constructing a continuous wall of the annular ultra-deep permanent foundation pit; the continuous wall is formed by pouring reinforced concrete along the edge of the foundation pit and is used for supporting the foundation pit;
s2: constructing pile integrated inner ring support piles, and arranging a plurality of pile integrated inner ring support piles along the continuous wall in the plane of the annular ultra-deep permanent foundation pit;
s3: excavating earthwork in a circular ultra-deep permanent foundation pit, constructing a lining wall and an annular beam, adopting a multi-layer once excavation and reverse-forward combination construction method for the circular ultra-deep permanent foundation pit and the lining wall, namely firstly excavating at least two layers of earthwork downwards continuously for each layer of the ultra-deep permanent foundation pit, constructing the lining wall in a mode of sequentially making at least two layers upwards from bottom to top, horizontally arranging the annular beam at the lower part of each layer of lining wall, and connecting the annular beam with pile integrated inner ring support piles to enable the pile integrated inner ring support piles and the annular beam to form pile integrated inner ring support structures for supporting the lining wall and the continuous wall;
s4: and S3, repeating the step after the strength of the lining wall meets the design requirement until the whole lining wall is built from top to bottom, and then constructing the bottom plate.
Through the steps, the annular ultra-deep permanent foundation pit supporting structure which is formed by the continuous wall, the pile integrated inner ring supporting structure and the lining wall is built efficiently.
Further, the distance between two adjacent pile integrated inner ring support piles in the same foundation pit is 3.5-10 m.
Further, the center line of the pile integrated inner ring support pile is 1.8-8 m away from the center line of the continuous wall.
Further, the pile integrated inner ring support piles can be vertically arranged outside the lining wall, radial connecting beams corresponding to the pile integrated inner ring support piles are arranged at the lower parts of the lining wall, one ends of the radial connecting beams are connected with the continuous wall, the other ends of the radial connecting beams are connected with the pile integrated inner ring support piles, the continuous wall, the lining wall, the radial connecting beams and the annular beams are jointly connected into a whole, and the inner lining wall and the continuous wall are supported by the pile integrated inner ring support piles outside the lining wall.
Further, the pile integrated inner ring support piles can be arranged outside the lining wall in an inclined mode, radial connecting beams corresponding to the pile integrated inner ring support piles are arranged at the lower parts of the lining wall in each layer, one ends of the radial connecting beams are connected with the continuous wall, the other ends of the radial connecting beams are connected with the pile integrated inner ring support piles, the continuous wall, the lining wall, the radial connecting beams and the annular beams are connected together to form a whole, so that the pile integrated inner ring support piles can bear certain transverse water and soil pressure while carrying out inclined support on the lining wall and the continuous wall, and the water and soil pressure resistance of the continuous wall is further improved.
Further, the pile integrated inner ring support pile can be a bored pile, a precast pile or a steel structure pile, a reinforced concrete pile, a steel or concrete combined pile.
The invention has the beneficial effects that:
1. the construction method of the annular ultra-deep (permanent) foundation pit supporting structure comprehensively considering the composite stress of annular pressure, bending shear and the like is provided, so that a wall supporting pile supporting structure system of annular continuous wall, pile integrated inner annular supporting piles and inner lining walls and a design and construction method thereof are formed, the integral supporting capacity and deformation resistance of the annular ultra-deep permanent foundation pit supporting structure are improved, and the safety risk of the annular ultra-deep permanent foundation pit supporting structure can be effectively controlled under the adverse conditions of uneven distribution of surrounding soil layers, uneven earth excavation, uneven piling of the surrounding soil layers, inconsistent and asymmetric depth of soil layer excavation, near-earth underground space and the like.
2. The construction joint between the lining wall and the continuous wall has larger bending shear stress and the construction joint between the lining wall has larger tensile stress, so that the construction joint is extremely easy to crack and water leakage is generated, and the foundation pit supporting structure can meet the functional requirement and the structural durability requirement that the service life of an ultra-deep permanent foundation pit is 50-100 years, and water leakage does not occur. And the foundation pit supporting structure can also be directly used as a part of an underground main body structure, so that the resource waste and the environmental pollution are effectively avoided, the construction period is shortened, the construction risk is reduced, and the construction cost is reduced.
3. Due to the fact that multi-layer primary excavation is formed for the annular ultra-deep permanent foundation pit, novel design and construction technology are combined in reverse and forward directions, for example, 7.5m deep earthwork (namely, 2.5m high is used as a small layer, three small layers of earthwork are excavated downwards continuously, and a large layer of earthwork with the total height of 7.5 m) can be excavated at one time, then three layers of lining walls (namely, 2.5m high lining walls are constructed on each layer) or two layers of lining walls (namely, 3.75m high lining walls are constructed on each layer) are constructed continuously and forward, design and construction bottlenecks of reverse construction of the traditional annular ultra-deep foundation pit lining wall in a mode that 3m layers (rings) are downwards layer by layer (rings) are broken through all the time, work efficiency is greatly improved, and construction of the annular ultra-deep permanent foundation pit is completed in a main flood period of Yangtze river.
Drawings
FIG. 1 is a top view of a pile-integrated inner ring support pile of a toroidal ultra-deep permanent pit support structure vertically disposed within a lining wall according to an embodiment of the present invention;
FIG. 2 is a cross-sectional view of a pile-integrated inner ring support pile of a toroidal ultra-deep permanent pit support structure vertically disposed within a lining wall, according to an embodiment of the present invention;
FIG. 3 is a top view of a pile-integrated inner ring support pile of a toroidal ultra-deep permanent pit support structure vertically disposed outside a lining wall according to an embodiment of the present invention;
FIG. 4 is a cross-sectional view of a pile-integrated inner ring support pile of a toroidal ultra-deep permanent pit support structure provided by an embodiment of the present invention vertically disposed outside a lining wall;
FIG. 5 is a cross-sectional view of a pile-integrated inner ring support pile of a toroidal ultra-deep permanent pit support structure provided by an embodiment of the present invention, disposed obliquely outside a lining wall;
FIG. 6 is a cross-sectional view of a construction joint between a lining wall and a continuous wall and between the lining wall and the lining wall, respectively, of a conventional annular ultra-deep permanent foundation pit supporting structure; wherein P is the tensile stress of the lower lining wall acting on the upper lining wall, M is the bending stress of the lining wall acting on the continuous wall, and F is the shear stress of the lining wall on the continuous wall.
In the figure: 1-continuous wall, 2-lining wall, 3-pile integrated inner ring supporting pile, 4-ring beam, 5-radial continuous beam and 6-soil layer.
Detailed Description
Embodiments of the present invention are described in further detail below with reference to the accompanying drawings and examples. The following examples are illustrative of the invention but are not intended to limit the scope of the invention.
The invention provides a high-efficiency construction method of a circular ultra-deep permanent foundation pit supporting structure, which comprises the steps of supporting a lining wall 2 and a continuous wall 1 by adding a pile integrated inner ring supporting structure, wherein the pile integrated inner ring supporting structure comprises a plurality of ring beams 4 horizontally arranged in the lining wall 2 and pile integrated inner ring supporting piles 3 which are arranged on the inner side of a foundation pit and are connected with the ring beams 4, and then constructing the circular ultra-deep permanent foundation pit and the lining wall 2 by adopting a multi-layer once excavation and reverse-forward combination construction method based on the pile integrated inner ring supporting structure, namely continuously excavating at least two layers of earthwork downwards, wherein the height of each layer of earthwork is at least 2.5m, and then constructing the lining wall 2 layer by layer at least in an efficient and sequential way.
The method specifically comprises the following steps:
s1, constructing a continuous wall 1 of a circular ultra-deep permanent foundation pit; the continuous wall 1 is formed by pouring reinforced concrete along the edge of the annular ultra-deep permanent foundation pit and is used for supporting the annular ultra-deep permanent foundation pit.
In this step, the continuous wall 1 adopts the grooving machine first, along the peripheral axis of the foundation pit engineering, under the condition of mud retaining wall, a long and narrow deep groove is excavated, after the groove is cleared, the reinforcement cage is hung in the groove, then the underwater concrete is poured by a conduit method to construct a unit groove section, and the steps are carried out section by section, so that a continuous reinforced concrete wall is constructed under the soil layer 6, and is used as the water interception, seepage prevention, bearing and soil retaining structure of the annular ultra-deep permanent foundation pit.
S2: constructing the pile integrated inner ring support pile 3; and a plurality of pile integrated inner ring support piles 3 are arranged along the continuous wall 1 in the plane of the annular ultra-deep permanent foundation pit.
In the step, holes are formed along the inner side of the continuous wall 1 of the annular foundation pit at intervals of 3.5 m-10 m by using hole forming equipment according to the point positions measured on the foundation pit, then a reinforcement cage is hung, and concrete is poured to form the pile integrated inner ring support pile 3. When the foundation pit earthwork is excavated later, the pile-integrated inner ring support piles 3 gradually expose the ground, and serve as support columns (therefore, referred to as pile-integrated inner ring support piles 3) together with the ring beams 4 to support the lining wall 2 and the continuous wall 1.
Of course, the pile-integrated inner ring support pile 3 may be not only the reinforced concrete pile, but also a precast pile, a steel structure pile, or a combined pile of steel and concrete.
S3: excavating earthwork in the annular ultra-deep permanent foundation pit, and constructing a lining wall 2 and an annular beam 4; the lining wall 2 and the ring beam 4 are both formed by pouring reinforced concrete, as the pile integrated inner ring support pile 3 and the ring beam 4 are added, most of the load of the lining wall 2 is borne by the pile integrated inner ring support pile 3, so that the invention adopts an efficient construction method of multi-layer primary excavation and reverse connection on the annular ultra-deep permanent foundation pit and the lining wall 2, namely, firstly, three layers of earthwork are excavated downwards continuously on the annular ultra-deep permanent foundation pit, the soil height of each layer is at least 2.5 meters, the annular beam 4 is horizontally arranged at the lower part of the lining wall 2, and the pile 4 is connected with the pile integrated inner ring support pile 3, and the pile integrated inner ring support wall 2 and the pile integrated inner ring support pile 2 are formed by constructing the annular ultra-deep permanent foundation pit from bottom to top (namely, constructing at least 2.5m high inner wall) or constructing the annular ultra-deep permanent foundation pit from bottom to top to bottom to at least 3.75m high inner ring support pile 3, and the pile integrated inner ring support pile 2 is formed by constructing the pile 1 and the annular support pile integrated inner ring support pile 2.
Of course, according to the soil property, the peripheral load and the groundwater condition, two layers of earthwork can be excavated continuously downwards, the height of each layer of earthwork is 3.75m, a large layer of earthwork with the height of 7.5m is excavated in total, then the lining wall 2 is constructed in a mode that two layers (namely, each layer of lining wall with the height of 3.75m is constructed) are sequentially and upwards made layer by layer, so that the pile integrated inner ring supporting piles 3 and the annular beam 4 form a pile integrated inner ring supporting structure to support the lining wall 2 and the continuous wall 1.
Excavating a 7.5m high large layer of earthwork from top to bottom in the whole ultra-deep foundation pit, and constructing 7.5m high lining walls for each large layer downwards layer by layer, which is called reverse construction; however, since each large layer of lining wall 2 with the height of 7.5m is divided into three layers or two layers for upward construction, the construction is called sequential operation; i.e., generally reverse operation, but layered upward construction of the lining wall 2 is also forward operation, the new design and construction process is referred to as "multi-layer once excavation, reverse-forward combination".
The lining wall 2 and the continuous wall 1 are supported by the pile integrated inner ring supporting structure, on one hand, the adverse stress state that the whole load of the lining wall 2 is borne by the connecting construction joint between the lining wall 2 and the continuous wall 1 in the traditional technology as shown in figure 6 is effectively changed, the bending shear stress of the construction joint between the lining wall 2 and the continuous wall 1 supporting structure is greatly reduced, meanwhile, the adverse stress state that the construction joint between the upper lining wall 2 and the lower lining wall 2 bears the tensile stress is effectively changed, thereby effectively solving the major engineering technical problems of the construction joint between the upper lining wall 2 and the lower lining wall 2, the construction joint crack between the lining wall 2 and the continuous wall 1 and water leakage, the method has the advantages that the integral supporting capability, the deformation resistance and the safety performance of the supporting structure are improved, on the other hand, the technical route and the technical bottleneck of traditional design and construction are broken through, and a high-efficiency construction method of multi-layer one-time excavation and reverse-forward combination is provided for constructing the annular ultra-deep permanent foundation pit and the lining wall 2, so that the foundation pit can excavate down to a deeper depth at one time (for example, three layers of earthwork can be excavated down continuously at one time, namely 7.5m of earthwork), and the lining wall 2 can be constructed into three layers from bottom to top (namely, 2.5m of high lining wall) or into two layers (namely, 3.75m of high lining wall 2) from each layer of high lining wall) continuously and efficiently and sequentially, the construction method is easier to connect into a whole, water leakage is difficult to occur, the construction efficiency is higher, and the construction period is shorter;
s4: and (3) repeating the step (S3) after the strength of the lining wall 2 meets the design requirement until the whole lining wall 2 is built from top to bottom, and then constructing a bottom plate.
Through the steps, the annular ultra-deep permanent foundation pit supporting structure which is formed by the continuous wall, the pile integrated inner ring supporting structure and the lining wall is built efficiently.
Further, the center line of the pile integrated inner ring support pile 3 is 1.8 m-8 m away from the center line of the continuous wall 1, so that the pile integrated inner ring support structure can flexibly support the lining wall 2 and the continuous wall 1 according to different use and construction requirements, as shown in fig. 1 and 2, when the lining wall 2 is thicker or the pile integrated inner ring support pile 3 is required to bear smaller water and soil pressure of a foundation pit, the pile integrated inner ring support pile 3 is vertically arranged inside the lining wall 2, so that the integral support effect of the lining wall 2 and the continuous wall 1 is improved.
As shown in fig. 3 and 4, when the thickness of the lining wall 2 is thin or the pile integrated inner ring support pile 3 is required to bear the pressure of soil and water in a foundation pit is large, the pile integrated inner ring support pile 3 is vertically arranged outside the lining wall 2, a radial connecting beam 5 corresponding to the pile integrated inner ring support pile 3 is arranged at the bottom of each layer of the lining wall 2, one end of the radial connecting beam 5 is connected with the continuous wall 1, and the other end of the radial connecting beam 5 is connected with the pile integrated inner ring support pile 3, so that the continuous wall 1, the lining wall 2, the pile integrated inner ring support pile 3, the radial connecting beam 5 and the annular beam 4 are jointly connected into a whole, the lining wall 2 and the continuous wall 1 are supported outside the lining wall 2, and most of loads of the reinforced concrete lining wall 2 and partial horizontal force when the annular ultra-deep permanent foundation pit drifting can be effectively born.
Similarly, as shown in fig. 5, as a preferred embodiment, the pile-integrated inner ring support piles 3 may be disposed outside the lining wall 2 in an oblique manner, and radial connecting beams 5 corresponding to the pile-integrated inner ring support piles 3 are disposed at the bottom of each layer of the lining wall 2, and one end of each radial connecting beam 5 is connected to the continuous wall 1, and the other end of each radial connecting beam is connected to the pile-integrated inner ring support piles 3, so that the continuous wall 1, the lining wall 2, the pile-integrated inner ring support piles 3, the radial connecting beams 5 and the annular beams 4 are integrally connected, and a certain transverse pressure can be borne while the lining wall 2 and the continuous wall 1 are obliquely supported outside the lining wall 2, so that the capability of resisting the water and soil pressure of the continuous wall 1 is further improved.
It should be noted that, the pile integrated inner ring support pile 3 in the invention has the characteristics of fundamentally different arrangement mode and function although the appearance is similar to that of the traditional double-row pile support pile of the ultra-deep foundation pit. The pit inner support piles of the traditional double-row pile support are in a continuous small-spacing densely-distributed mode, the spacing is smaller, the common spacing is 0.5-0.8 m, the pit outer support piles are also in a continuous small-spacing densely-distributed mode, the spacing is smaller, the common spacing is 0.5-2.0 m, the pit outer support piles are tightly connected with the soil layer 6 to be supported, and the pit inner support piles and the pit outer support piles bear the horizontal force transmitted by the soil body together and play roles of soil blocking and water stopping. If the supporting piles are arranged at large intervals, water leakage and soil flowing among the piles can occur; especially, before the earthwork is excavated, the crown beam and the capping beam are arranged at the top of the double-row piles to connect the tops of the double-row piles (but other elevation positions cannot be connected), namely, after the front row piles (in-pit piles) and the rear row piles (out-pit piles) are connected into a whole at the tops of the piles, the earthwork is excavated, and the front row support piles and the rear row support piles are simultaneously stressed together after the earthwork is excavated. The pile integrated inner ring support pile 3 is different from the pile row in arrangement position, stress and connection mode, and plays a role, firstly, the pile integrated inner ring support pile 3 is arranged in a foundation pit, but not outside the foundation pit; secondly, before the foundation pit is excavated, as the pile integrated inner ring support pile 3 is not directly connected with the continuous wall 1, when the continuous wall 1 is stressed after the foundation pit is excavated, the pile integrated inner ring support pile 3 positioned in the foundation pit is not stressed yet; because the lining wall 2 is firstly excavated by earthwork and then constructed, then the lining wall 2 and the continuous wall 1 are connected into a whole through the pile integrated inner ring supporting structure, and when the concrete strength of the lining wall 2 reaches the design requirement and the earthwork is excavated downwards, the pile integrated inner ring supporting pile 3 and the continuous wall 1 are stressed together. Thirdly, the pile integrated inner ring supporting piles 3 are connected with the continuous wall 1 at the lining wall in each layer; fourthly, pile integrated inner ring supporting piles 3 are arranged at large intervals, the intervals are 3.5 m-10 m, the pile integrated inner ring supporting piles are not tightly connected with the soil body to be supported, the pile integrated inner ring supporting piles mainly play a role in supporting the vertical load of the lining wall 2, and meanwhile, certain horizontal force is born.
According to the invention, the pile integrated inner ring support structure is added inside the lining wall 2 or outside the lining wall 2, the pile integrated inner ring support pile 3 bears most of the load of the lining wall 2, the pile integrated inner ring support structure, the continuous wall 1 and the lining wall 2 jointly form a novel support structure of a circular continuous wall, the pile integrated inner ring support structure and the wall support pile of the lining wall, so that the technical problems that a construction joint between the lining wall 2 and the continuous wall 1 has large bending shear stress and a construction joint between the upper part and the lower part of the lining wall 2 has large tensile stress in the prior art are solved, so that the construction joint is easy to crack to generate water leakage are solved, the durability of the permanent support structure is improved, the service requirement of 50-100 years is met, and the integral support capacity and deformation resistance of the circular ultra-deep permanent foundation pit are improved. Meanwhile, by implementing multilayer once excavation on the circular ultra-deep permanent foundation pit and combining a novel design and construction process and method in reverse and forward directions, the novel construction method breaks through the fact that the circular ultra-deep foundation pit lining wall 2 can only be constructed in a layer (ring) reverse way downwards layer by layer (ring) layer by layer only in a layer (ring) mode in the traditional construction process, greatly improves working efficiency, shortens construction period, and achieves the aim that a 40m ultra-deep permanent foundation pit is efficiently and safely used for completing a circular ultra-deep permanent foundation pit supporting structure in a main flood period of a Yangtze river.
The above embodiments are only for illustrating the present invention, and are not limiting of the present invention. While the invention has been described in detail with reference to the embodiments, those skilled in the art will appreciate that various combinations, modifications, and substitutions can be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (3)
1. A high-efficiency construction method of a circular ultra-deep permanent foundation pit supporting structure is characterized by comprising the following steps of: the method comprises the following steps:
s1: constructing a continuous wall of the annular ultra-deep permanent foundation pit; the continuous wall is formed by pouring reinforced concrete along the edge of the foundation pit and is used for supporting the annular ultra-deep permanent foundation pit;
s2: constructing pile integrated inner ring support piles, and arranging a plurality of pile integrated inner ring support piles along the continuous wall in the plane of the annular ultra-deep permanent foundation pit;
the pile and column integrated inner ring support pile is a reinforced concrete pile, a precast pile, a steel structure pile or a combined pile of steel and concrete;
s3: excavating earthwork in the annular ultra-deep permanent foundation pit, constructing lining walls and ring beams, adopting a multi-layer once excavation and reverse-forward combination construction method for the annular ultra-deep permanent foundation pit and the lining walls, namely firstly excavating at least two layers of earthwork downwards continuously for each layer of ultra-deep permanent foundation pit, wherein the height of each layer of earthwork is at least 2.5 meters, then constructing the lining walls in a mode of dividing the earthwork into at least two layers from bottom to top, and simultaneously horizontally arranging the ring beams at the lower part of each lining wall, connecting the ring beams with pile integrated inner ring support piles, and supporting the pile integrated inner ring support piles and the ring beams into pile integrated inner ring support structures for supporting the lining walls and the continuous walls;
the pile integrated inner ring support piles are vertically arranged outside the lining wall, radial connecting beams corresponding to the pile integrated inner ring support piles are arranged at the lower part of each layer of the lining wall, one end of each radial connecting beam is connected with the continuous wall, and the other end of each radial connecting beam is connected with the pile integrated inner ring support piles, so that the pile integrated inner ring support piles, the continuous wall, the lining wall, the radial connecting beams and the annular beams are connected together into a whole, and the pile integrated inner ring support piles support the lining wall and the continuous wall outside the lining wall;
the pile integrated inner ring support piles are arranged outside the lining wall or are obliquely arranged, radial connecting beams corresponding to the pile integrated inner ring support piles are arranged at the lower part of each layer of the lining wall, one end of each radial connecting beam is connected with the continuous wall, the other end of each radial connecting beam is connected with the pile integrated inner ring support piles, the continuous wall, the lining wall, the radial connecting beams and the annular beams are integrally connected together, so that the pile integrated inner ring support piles can bear certain transverse water and soil pressure while obliquely supporting the lining wall and the continuous wall, and the capability of the continuous wall for resisting water and soil pressure is further improved;
s4: repeating S3 after the strength of the lining wall meets the design requirement until the whole lining wall is built from top to bottom, and then constructing a bottom plate; through the steps, the annular ultra-deep permanent foundation pit supporting structure which is formed by the continuous wall, the pile integrated inner ring supporting structure and the lining wall is built efficiently.
2. The method for efficiently constructing the annular ultra-deep permanent foundation pit supporting structure according to claim 1, wherein the method comprises the following steps: the distance between the two pile integrated inner ring support piles is 3.5 m-10 m.
3. The method for efficiently constructing the annular ultra-deep permanent foundation pit supporting structure according to claim 1, wherein the method comprises the following steps: the center line of the pile integrated inner ring support pile is 1.8-8 m away from the center line of the continuous wall.
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