CN111155532A - Deep foundation pit supporting structure and construction method thereof - Google Patents
Deep foundation pit supporting structure and construction method thereof Download PDFInfo
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- CN111155532A CN111155532A CN202010041728.4A CN202010041728A CN111155532A CN 111155532 A CN111155532 A CN 111155532A CN 202010041728 A CN202010041728 A CN 202010041728A CN 111155532 A CN111155532 A CN 111155532A
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- 230000008093 supporting effect Effects 0.000 title claims abstract description 43
- 238000010276 construction Methods 0.000 title claims abstract description 38
- 239000004568 cement Substances 0.000 claims abstract description 129
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 63
- 239000010959 steel Substances 0.000 claims abstract description 63
- 238000000034 method Methods 0.000 claims description 11
- 239000002689 soil Substances 0.000 claims description 9
- 238000004140 cleaning Methods 0.000 claims description 3
- 238000009412 basement excavation Methods 0.000 abstract description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 13
- 239000012530 fluid Substances 0.000 description 3
- 239000011499 joint compound Substances 0.000 description 3
- 239000004576 sand Substances 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 239000011150 reinforced concrete Substances 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 238000004642 transportation engineering Methods 0.000 description 1
- 238000009966 trimming Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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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
- E02D19/00—Keeping dry foundation sites or other areas in the ground
- E02D19/06—Restraining of underground water
- E02D19/12—Restraining of underground water by damming or interrupting the passage of underground water
- E02D19/18—Restraining of underground water by damming or interrupting the passage of underground water by making use of sealing aprons, e.g. diaphragms made from bituminous or clay material
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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
- E02D5/02—Sheet piles or sheet pile bulkheads
- E02D5/03—Prefabricated parts, e.g. composite sheet piles
- E02D5/04—Prefabricated parts, e.g. composite sheet piles made of steel
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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
- E02D5/46—Concrete or concrete-like piles cast in position ; Apparatus for making same making in situ by forcing bonding agents into gravel fillings or the soil
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D2250/00—Production methods
- E02D2250/0023—Cast, i.e. in situ or in a mold or other formwork
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Abstract
The invention provides a deep foundation pit supporting structure and a construction method thereof, wherein the deep foundation pit supporting structure comprises a first cement mixing pile enclosure, a steel sheet pile enclosure, a high-pressure jet grouting pile enclosure used as a waterproof curtain, a cast-in-place pile enclosure, an inner foundation pit support, a plurality of rows of second cement mixing pile rows and a plurality of steel pipe piles. The invention has convenient construction, is safe and effective, can reinforce the foundation of the foundation pit, reduces the complexity of the foundation, ensures the stability of the foundation and effectively controls the excavation safety of the deep foundation pit.
Description
Technical Field
The invention belongs to the field of underground structural engineering, and particularly relates to a deep foundation pit supporting structure and a construction method thereof.
Background
With the economic development of China, the large-scale development of construction engineering is a necessary trend, and in the construction process of water transport engineering, the deep foundation pit is used as a foundation part of a large-scale building, so that the construction requirement is extremely strict. The deep foundation pit engineering mainly considers the requirements of construction safety and engineering quality.
Because the construction depth of the deep foundation pit is very large, the construction safety and the construction quality are easily influenced by geological conditions in the construction process, the expansion of the deep foundation pit engineering is greatly restricted, and the geological complexity of the foundation pit causes great troubles to the engineering in the construction process.
Disclosure of Invention
The invention aims to provide a deep foundation pit supporting structure and a construction method thereof, which are convenient to construct, safe and effective, can be used for reinforcing a foundation pit foundation, reduce the complexity of the foundation, ensure the stability of the foundation and effectively control the excavation safety of a deep foundation pit.
The invention is realized by the following technical scheme:
a deep foundation pit supporting structure comprises a first cement mixing pile surrounding baffle, a steel sheet pile surrounding baffle, a high-pressure jet grouting pile surrounding baffle used as a waterproof curtain, a filling pile surrounding baffle, a foundation pit inner support, a plurality of rows of second cement mixing pile rows and a plurality of steel pipe piles, wherein the first cement mixing pile surrounding baffle is formed by a plurality of circles of first cement mixing piles which are mutually in gapless lap joint;
the steel sheet pile surrounding baffle, the cast-in-place pile surrounding baffle and the high-pressure jet grouting pile surrounding baffle used as a waterproof curtain are all arranged in an area surrounded by the first cement mixing pile at the innermost ring in the first cement mixing pile surrounding baffle;
the cast-in-place pile enclosure is an annular enclosure which is formed by a plurality of cast-in-place piles which are arranged at equal intervals, and any two adjacent cast-in-place piles form a cast-in-place pile group;
the high-pressure jet grouting pile enclosure used as a waterproof curtain is arranged on the outer side of the cast-in-place pile enclosure and comprises high-pressure jet grouting piles which correspond to the cast-in-place pile groups in the cast-in-place pile enclosure one by one, and the high-pressure jet grouting piles are in gapless lap joint with two cast-in-place piles of the cast-in-place pile groups corresponding to the high-pressure jet grouting piles;
the steel sheet pile enclosure is arranged between the high-pressure jet grouting pile enclosure used as a waterproof curtain and the first cement mixing pile at the innermost ring in the first cement mixing pile enclosure, and is an annular enclosure formed by sequentially connecting a plurality of steel sheet piles;
a plurality of rows of second cement mixing pile rows are arranged in the area surrounded by the filling pile enclosure at equal intervals, and each row of second cement mixing pile rows consists of a plurality of second cement mixing piles which are mutually overlapped without gaps;
the end part of the foundation pit inner support is abutted against the inner side surface of the cast-in-place pile enclosure;
the steel pipe piles are arranged in the area surrounded by the cast-in-place pile enclosure and used for supporting the foundation pit inner support, and the steel pipe piles are not in contact with the second cement mixing pile;
the filling pile enclosure is provided with a plurality of supporting ring beams.
Compared with the prior art, the invention has the beneficial effects that: convenient construction, safe effective and can consolidate the foundation ditch ground, reduce ground complexity, ensure to the ground steadiness, solved the place condition that the geology is complicated under, to the restriction of deep basal pit engineering, the problem of deep basal pit support construction difficulty, make deep basal pit excavation safety obtain effective control, ensure pier engineering construction and safe in utilization. The deep foundation pit supporting structure has the advantages of high integral rigidity, good waterproof performance and large depth of the applied foundation pit, and the excavation depth of the foundation pit can exceed 15 meters.
Furthermore, the distance between two adjacent circles of first cement mixing piles in the first cement mixing pile enclosure is equal, the adjacent first cement mixing piles in the same circle are in gapless lap joint, and the radial lap joint length between the adjacent first cement mixing piles in the same circle is one third of the pile diameter of the first cement mixing piles.
Further, the distance between two adjacent circles of first cement mixing piles in the first cement mixing pile retaining wall is 1-2 m.
Furthermore, the first cement mixing pile enclosure is formed by three circles of first cement mixing piles which are mutually overlapped without gaps.
Further, the radial overlap length between the adjacent second cement mixing piles in the same row is one third of the pile diameter of the second cement mixing piles.
Further, the spacing between adjacent cast-in-place piles is 100-200 mm.
Further, the radial overlap length between the high-pressure jet grouting pile and the cast-in-place pile is 100-150 mm.
Furthermore, the distance between the steel plate pile enclosure and the high-pressure jet grouting pile enclosure is 50-100 mm.
Furthermore, the foundation pit inner support comprises a transverse inner support and a longitudinal inner support, the transverse inner support and the longitudinal inner support are vertically arranged, two ends of the transverse inner support respectively abut against two different sides of the periphery of the cast-in-place pile, two ends of the longitudinal inner support also respectively abut against two different sides of the periphery of the cast-in-place pile, the lower parts of the steel pipe piles are respectively inserted into the ground, and the upper parts of the steel pipe piles are respectively located at the connecting node positions of the transverse inner support and the longitudinal inner support and used for supporting the transverse inner support and the longitudinal inner support.
The invention also provides a construction method of the deep foundation pit supporting structure, which comprises the following steps:
1) cleaning and leveling a ground of a foundation pit to be excavated;
2) paying off and positioning the positions of the first cement mixing pile, the second cement mixing pile, the cast-in-place pile and the steel pipe pile according to the construction drawing;
3) constructing a first cement mixing pile: arranging a plurality of circles of first cement mixing piles around the outer side of the foundation pit according to the paying-off position, and constructing the cement mixing piles to the designed depth;
4) constructing a second cement mixing pile: arranging a plurality of rows of second cement mixing piles at equal intervals on the inner side of the foundation pit according to the setting-out position, and constructing the second cement mixing piles to the designed depth;
5) constructing the steel pipe pile: arranging a plurality of steel pipe piles on the inner side of the foundation pit according to the paying-off position, and constructing the steel pipe piles to the designed depth;
6) constructing a cast-in-place pile: arranging a circle of cast-in-place piles around the periphery of the foundation pit according to the paying-off position, constructing the cast-in-place piles to the designed depth, and enabling the intervals between the adjacent cast-in-place piles to be equal;
7) after the construction of the cast-in-place piles is finished, constructing a high-pressure jet grouting pile between two adjacent cast-in-place piles to the designed depth along the circumferential outer sides of the cast-in-place piles;
8) after the high-pressure jet grouting pile is constructed, constructing a steel sheet pile to a designed depth along the circumferential outer side of the high-pressure jet grouting pile by a specified distance;
9) excavating foundation soil in an area surrounded by the innermost first cement mixing pile in a subsection and layer-by-layer mode according to design requirements, and meanwhile, erecting a supporting ring beam and a foundation pit inner support on a cast-in-place pile layer by layer from top to bottom;
10) and after the last layer of support ring beam and the foundation pit inner support are erected, continuously excavating the foundation pit to the top surface of the second cement mixing pile.
Drawings
Fig. 1 is a schematic top view of the deep foundation pit supporting structure of the present invention.
In the figure, 1-a first cement mixing pile enclosure, 2-a steel plate pile enclosure, 3-a high-pressure jet grouting pile enclosure used as a waterproof curtain, 4-a filling pile enclosure, 41-a support ring beam, 5-an inner foundation pit support, 51-a transverse inner support, 52-a longitudinal inner support, 6-a second cement mixing pile row and 7-a steel pipe pile.
Detailed Description
The invention is further illustrated by the following figures and examples.
Referring to fig. 1, fig. 1 is a schematic top view of a deep foundation pit supporting structure according to the present invention. A deep foundation pit supporting structure comprises a first cement mixing pile surrounding baffle 1, a steel sheet pile surrounding baffle 2, a high-pressure jet grouting pile surrounding baffle 3 used as a waterproof curtain, a filling pile surrounding baffle 4, a foundation pit inner support 5, a plurality of rows of second cement mixing pile rows 6 and a plurality of steel pipe piles 7, wherein the first cement mixing pile surrounding baffle 1 is formed by a plurality of circles of mutually gapless lapped first cement mixing piles; the steel sheet pile surrounding baffle 2, the cast-in-place pile surrounding baffle 4 and the high-pressure jet grouting pile surrounding baffle 3 used as a waterproof curtain are all arranged in an area surrounded by the first cement mixing pile at the innermost ring in the first cement mixing pile surrounding baffle 1; the cast-in-place pile enclosure 4 is an annular enclosure which is formed by a plurality of cast-in-place piles which are arranged at equal intervals, and any two adjacent cast-in-place piles form a cast-in-place pile group; the high-pressure jet grouting pile enclosure 3 used as a waterproof curtain is arranged on the outer side of the cast-in-place pile enclosure 4 and comprises high-pressure jet grouting piles which correspond to the cast-in-place pile groups in the cast-in-place pile enclosure 4 one by one, and the high-pressure jet grouting piles are in gapless lap joint with two cast-in-place piles of the cast-in-place pile groups corresponding to the high-pressure jet grouting piles; the steel sheet pile enclosure 2 is arranged between the high-pressure jet grouting pile enclosure 3 used as a waterproof curtain and the first cement mixing pile at the innermost ring in the first cement mixing pile enclosure 1, and the steel sheet pile enclosure 2 is an annular enclosure formed by sequentially connecting a plurality of steel sheet piles; a plurality of rows of second cement mixing pile rows 6 are arranged in the area surrounded by the cast-in-place pile enclosure 4 at equal intervals, and each row of second cement mixing pile rows 6 consists of a plurality of second cement mixing piles which are mutually overlapped without gaps; the end part of the foundation pit inner support 5 is abutted against the inner side surface of the cast-in-place pile enclosure 4; the steel pipe piles 7 are arranged in the area surrounded by the cast-in-place pile enclosure 4 and used for supporting the foundation pit inner support 5, and the steel pipe piles 7 are not in contact with the second cement mixing pile; the cast-in-place pile enclosure 4 is provided with a plurality of supporting ring beams 41.
The first cement mixing pile and the second cement mixing pile are both daily-used cement mixing piles, and the pile diameters of the first cement mixing pile and the second cement mixing pile are 400-plus-800 mm. When the first cement mixing pile is constructed, the bottom elevation of the first cement mixing pile can be the same as the bottom elevation of the foundation pit or slightly smaller than the bottom elevation of the foundation pit; when the second cement mixing pile is constructed, the top elevation of the second cement mixing pile is the same as the bottom elevation of the foundation pit, and the deep cement mixing pile construction process can be adopted for the second cement mixing pile construction to reinforce the deep soft soil foundation of the foundation pit. In an embodiment, the distance between two adjacent circles of first cement mixing piles in the first cement mixing pile enclosure 1 is equal, the adjacent first cement mixing piles in the same circle are overlapped without gaps, and the length of the radial overlap joint between the adjacent first cement mixing piles in the same circle is one third of the pile diameter of the first cement mixing piles. In one embodiment, the distance between two adjacent circles of the first cement mixing piles in the first cement mixing pile enclosure 1 is 1-2 m. In one embodiment, the first cement mixing pile surround 1 is formed by three rings of first cement mixing piles which are overlapped without gaps. In one embodiment, the radial overlap length between adjacent second cement mixing piles in the same row is one third of the pile diameter of the second cement mixing piles. Herein, the radial overlap length between two adjacent piles refers to the maximum overlapping length of two adjacent piles in the diameter direction.
The cast-in-place pile is used as a support pile of the foundation pit, a daily cast-in-place pile can be adopted, the cast-in-place pile enclosure 4 is provided with a plurality of support ring beams 41, and the number of the support ring beams 41 can be set according to actual needs. In one embodiment, the spacing between adjacent cast-in-place piles is 100-200 mm. The high-pressure jet grouting pile is used as a waterproof curtain, is constructed in a gap between the cast-in-place piles and is arranged outside the cast-in-place piles, the pile diameter of the high-pressure jet grouting pile is required to be larger than the gap between the adjacent cast-in-place piles, and is in lap joint with the cast-in-place piles, and the high-pressure jet grouting pile is mainly used for preventing water outside the foundation pit from permeating into the foundation pit in the excavation process and after the foundation pit is. In one embodiment, the radial overlap length between the high-pressure jet grouting pile and the cast-in-place pile is 100-150 mm. And the steel sheet pile is constructed on the outer side of the high-pressure jet grouting pile, primary isolation is carried out on underground water, sand, mud and other fluid on the outer side of the foundation pit, and the fluidity of the soft soil on the outer side in the excavation process of the foundation pit is reduced. In one embodiment, the distance between the steel plate pile enclosure 2 and the high-pressure jet grouting pile enclosure is 50-100 mm.
The foundation pit inner support 5 comprises a transverse inner support 51 and a longitudinal inner support 52, the transverse inner support 51 and the longitudinal inner support 52 are vertically arranged, two ends of the transverse inner support 51 respectively abut against two different sides of the cast-in-place pile enclosure 4, two ends of the longitudinal inner support 52 also respectively abut against two different sides of the cast-in-place pile enclosure 4, the lower parts of the steel pipe piles 7 are respectively inserted into the ground, and the upper parts of the steel pipe piles are respectively located at the connecting node positions of the transverse inner support 51 and the longitudinal inner support 52 and used for supporting the transverse inner support 51 and the longitudinal inner support 52. The foundation pit inner support 5 is of a steel structure and can also be of a reinforced concrete structure. The deep foundation pit supporting structure's in the foundation ditch support 5 can design the multilayer according to actual need, and every layer of foundation pit supports 5's structure the same, and the connection node that lies in horizontal interior support 51 and vertical interior support 52 on same plumb line in the multilayer foundation pit support 5 is a set of connection node group, and a plurality of connection node groups one-to-one correspond to a plurality of steel-pipe piles 7, and the connection node in the connection node group all sets up the upper portion at corresponding steel-pipe pile 7. The steel pipe pile 7 plays a supporting role in the middle of the transverse inner support 51 and the longitudinal inner support 52 on each layer of foundation pit inner support 5, and the supporting effect of the foundation pit due to the influence of overlong arrangement lengths of the transverse inner support 51 and the longitudinal inner support 52 in the foundation pit is avoided. In an embodiment, the lateral inner supports 51 equally divide the bottom area of the foundation pit into a plurality of parts, the longitudinal inner supports 52 also equally divide the bottom area of the foundation pit into a plurality of parts, for example, on each layer of foundation pit inner supports 5, the number of the lateral inner supports 51 is two, the number of the longitudinal inner supports 52 is also two, two lateral inner supports 51 equally divide the bottom area of the foundation pit into three parts, two longitudinal inner supports 52 equally divide the bottom area of the foundation pit into three parts, and four nodes are shared between two lateral inner supports 51 and two longitudinal inner supports 52, so that the number of the steel pipe piles 7 is four.
The invention also provides a construction method of the deep foundation pit supporting structure, which comprises the following steps:
1) cleaning and leveling a ground of a foundation pit to be excavated;
in the step 1), for example, the surface construction waste of the field with the excavated foundation pit, the abandoned underground facilities and the like are cleaned.
2) Paying off and positioning 7 positions of the first cement mixing pile, the second cement mixing pile, the cast-in-place pile and the steel pipe pile according to the construction drawing;
and in the step 2), paying off and positioning 7 positions of the first cement mixing pile, the second cement mixing pile, the filling pile and the steel pipe pile on the flat site of the foundation pit to be excavated according to a design construction drawing, so that the subsequent construction of each pile is facilitated. And 2) paving a temporary road according to the position of the paying-off positioning, and arranging a drainage ditch and a water collecting pit at the inner side of the foundation pit to be dug.
3) Constructing a first cement mixing pile: arranging a plurality of circles of first cement mixing piles around the outer side of the foundation pit according to the paying-off position, and constructing the cement mixing piles to the designed depth;
in step 3), the first cement mixing piles can be arranged in three circles, the distance between every two adjacent circles of the first cement mixing piles is 1-2m, the radial lap joint length between every two adjacent circles of the first cement mixing piles is one third of the pile diameter of the first cement mixing piles, and the bottom elevation of each first cement mixing pile is the same as the bottom elevation of the foundation pit.
4) Constructing a second cement mixing pile: arranging a plurality of rows of second cement mixing piles at equal intervals on the inner side of the foundation pit according to the setting-out position, and constructing the second cement mixing piles to the designed depth;
in the step 4), multiple rows are evenly distributed according to the area of the foundation pit, the radial overlap length between adjacent second cement mixing piles in the same row is one third of the pile diameter of the second cement mixing piles, and the top elevation of the second cement mixing piles is the same as the bottom elevation of the foundation pit.
5) Constructing a steel pipe pile 7: arranging a plurality of steel pipe piles 7 on the inner side of the foundation pit according to the paying-off position, and constructing the steel pipe piles 7 to the designed depth;
in the step 5), the steel pipe pile 7 is a middle support of the foundation pit inner support 5 and is arranged at the joint position of the transverse inner support 51 and the longitudinal inner support 52 of the foundation pit inner support 5, and the bottom elevation of the steel pipe pile 7 is lower than that of the foundation pit.
6) Constructing a cast-in-place pile: arranging a circle of cast-in-place piles around the periphery of the foundation pit according to the paying-off position, constructing the cast-in-place piles to the designed depth, and enabling the intervals between the adjacent cast-in-place piles to be equal;
in the step 6), the cast-in-place piles are supporting piles of the foundation pit, the distance between every two adjacent cast-in-place piles is 100-200mm, and the bottom elevation of each cast-in-place pile is lower than that of the foundation pit.
7) After the construction of the cast-in-place piles is finished, constructing a high-pressure jet grouting pile between two adjacent cast-in-place piles to the designed depth along the circumferential outer sides of the cast-in-place piles;
in the step 7), the high-pressure jet grouting pile is used as a waterproof curtain, the high-pressure jet grouting pile is constructed in a gap between two adjacent cast-in-place piles and is arranged outside the cast-in-place pile, the pile diameter requirement of the high-pressure jet grouting pile is larger than the numerical value of the gap between the cast-in-place piles and forms lap joint with the cast-in-place piles, the length of the radial lap joint between the high-pressure jet grouting pile and the cast-in-place pile is 100-150mm, the main function is to prevent water on the outer side of the foundation pit from permeating into the foundation pit in the process of excavation of the foundation pit and after the excavation.
8) After the high-pressure jet grouting pile is constructed, constructing a steel sheet pile to a designed depth along the circumferential outer side of the high-pressure jet grouting pile by a specified distance;
in the step 8), the steel sheet pile is constructed on the outer side of the high-pressure jet grouting pile, the distance between the steel sheet pile and the high-pressure jet grouting pile is 50-100mm, underground water, sand, mud and other fluid on the outer side of the foundation pit are isolated for the first time, the fluidity of outer soft soil in the ultra-deep foundation pit excavation process is reduced, the bottom elevation of the steel sheet pile is the same as that of the foundation pit, or the bottom elevation of the steel sheet pile is lower than that of the foundation pit.
9) Excavating foundation soil in an area surrounded by the innermost first cement mixing pile in a subsection and layer-by-layer mode according to design requirements, and meanwhile, erecting a support ring beam 41 and a foundation pit inner support 5 on a cast-in-place pile layer by layer from top to bottom;
before step 9), a support ring beam 41 is constructed at the top end of the cast-in-place pile to serve as a first support. In step 9), when the support segmental construction is performed after each layered excavation, namely after the support ring beam 41 and the foundation pit inner support 5 are erected, drainage ditches and water collection pits need to be newly arranged, and drainage is performed in time.
10) After the last layer of support ring beam 41 and the foundation pit inner support 5 are erected, the foundation pit is continuously excavated to the top surface of the second cement mixing pile.
In the step 10), when the foundation pit is excavated to the height 300mm away from the designed bottom, manual excavation and trimming are carried out until the top surface of the first cement mixing pile is reached.
The first cement mixing pile enclosure 1 is arranged around the outer side of the foundation pit, and the foundation strength of the outer soft soil in the excavation process of the ultra-deep foundation pit can be enhanced by a plurality of circles of the first cement mixing piles, and the mobility of underground water can be reduced preliminarily; multiple rows of second cement mixing piles are evenly distributed on the inner side of the foundation pit, so that the foundation pit foundation can be reinforced, the complexity of the foundation is reduced, the stability of the foundation is ensured, and the excavation safety of the deep foundation pit is effectively controlled; the cast-in-place pile is used as a support pile of the ultra-deep foundation pit, the area surrounded by the cast-in-place pile is the area of the ultra-deep foundation pit, and the cast-in-place pile plays a role in supporting the foundation pit after excavation, so that the feasibility and the safety of foundation pit excavation construction are ensured; the support ring beam 41 and the foundation pit inner support 5 are arranged on the cast-in-place pile, and the support ring beam 41 improves the rigidity of the cast-in-place pile, increases the integrity of the cast-in-place pile and improves the shearing resistance and tensile strength of the cast-in-place pile; the steel pipe pile 7 is arranged in the ultra-deep foundation pit range, plays a supporting role for the foundation pit inner support 5 and serves as a middle supporting role for foundation pit enclosure; the high-pressure jet grouting pile is used as a waterproof curtain, is constructed in a gap between two adjacent cast-in-place piles and is arranged on the outer side of the cast-in-place pile, and is in gapless lap joint with the two adjacent cast-in-place piles to form a firm lateral waterproof curtain, no gap exists on the lateral waterproof curtain, a watertight space is formed together with the cast-in-place piles, underground water on the periphery of the lateral waterproof curtain hardly permeates into an ultra-deep foundation pit, soil bodies around the ultra-deep foundation pit cannot be settled, secondary damage to surrounding buildings cannot be caused, the supporting structure is good in waterproof performance, and basic conditions are created for dry operation excavation construction of the ultra-deep foundation pit. The steel sheet pile is arranged between the high-pressure jet grouting pile and the first cement mixing pile surrounding baffle 1 located on the innermost side and used as supplementary water stop of the high-pressure jet grouting pile water stop curtain to primarily isolate underground water, sand, mud and other fluid on the outer side of the ultra-deep foundation pit, the fluidity of the soft soil on the outer side in the excavation process of the ultra-deep foundation pit is reduced, the ultra-deep foundation pit is further ensured to be difficult to enter the underground water, the stability and reliability of a watertight space are ensured, and the feasibility and the safety of the excavation construction of the ultra-deep foundation pit are ensured.
Compared with the prior art, the invention has the beneficial effects that: convenient construction, safe effective and can consolidate the foundation ditch ground, reduce ground complexity, ensure to the ground steadiness, solved the place condition that the geology is complicated under, to the restriction of deep basal pit engineering, the problem of deep basal pit support construction difficulty, make deep basal pit excavation safety obtain effective control, ensure pier engineering construction and safe in utilization. The deep foundation pit supporting structure has the advantages of high integral rigidity, good waterproof performance and large depth of the applied foundation pit, and the excavation depth of the foundation pit can exceed 15 meters.
The present invention is not limited to the above-described embodiments, and various modifications and variations of the present invention are intended to be included within the scope of the claims and the equivalent technology of the present invention if they do not depart from the spirit and scope of the present invention.
Claims (10)
1. A deep foundation pit supporting structure is characterized by comprising a first cement mixing pile surrounding baffle, a steel sheet pile surrounding baffle, a high-pressure jet grouting pile surrounding baffle used as a waterproof curtain, a filling pile surrounding baffle, a foundation pit inner support, a plurality of rows of second cement mixing pile rows and a plurality of steel pipe piles, wherein the first cement mixing pile surrounding baffle is formed by a plurality of circles of first cement mixing piles which are mutually in gapless lap joint;
the steel sheet pile surrounding baffle, the cast-in-place pile surrounding baffle and the high-pressure jet grouting pile surrounding baffle used as a waterproof curtain are all arranged in an area surrounded by the first cement mixing pile at the innermost ring in the first cement mixing pile surrounding baffle;
the cast-in-place pile enclosure is an annular enclosure which is formed by a plurality of cast-in-place piles which are arranged at equal intervals, and any two adjacent cast-in-place piles form a cast-in-place pile group;
the high-pressure jet grouting pile enclosure used as the waterproof curtain is arranged on the outer side of the cast-in-place pile enclosure and comprises high-pressure jet grouting piles which correspond to cast-in-place pile groups in the cast-in-place pile enclosure one by one, and the high-pressure jet grouting piles are in gapless lap joint with two cast-in-place piles of the cast-in-place pile groups corresponding to the high-pressure jet grouting piles;
the steel sheet pile enclosure is arranged between the high-pressure jet grouting pile enclosure used as a waterproof curtain and the first cement mixing pile at the innermost ring in the first cement mixing pile enclosure, and is an annular enclosure formed by sequentially connecting a plurality of steel sheet piles;
the plurality of rows of second cement mixing pile rows are arranged in an area surrounded by the cast-in-place pile enclosure at equal intervals, and each row of second cement mixing pile rows consists of a plurality of second cement mixing piles which are mutually overlapped without gaps;
the end part of the foundation pit inner support is abutted against the inner side surface of the cast-in-place pile enclosure;
the steel pipe piles are arranged in the area surrounded by the cast-in-place pile enclosure and used for supporting the foundation pit inner support, and the steel pipe piles are not in contact with the second cement mixing pile;
and a plurality of supporting ring beams are arranged on the cast-in-place pile enclosure.
2. The deep foundation pit supporting structure according to claim 1, wherein the distance between two adjacent circles of the first cement mixing piles in the first cement mixing pile retaining wall is equal, the adjacent first cement mixing piles in the same circle are overlapped without a gap, and the length of the radial overlap joint between the adjacent first cement mixing piles in the same circle is one third of the pile diameter of the first cement mixing piles.
3. The deep foundation pit supporting structure according to claim 2, wherein the distance between two adjacent circles of the first cement mixing piles in the first cement mixing pile retaining wall is 1-2 m.
4. The deep foundation pit supporting structure according to claim 1, wherein the first cement mixing pile enclosure is formed by three rings of first cement mixing piles which are overlapped without gaps therebetween.
5. The deep foundation pit supporting structure of claim 1, wherein a radial overlap length between adjacent second cement mixing piles in the same row is one third of a pile diameter of the second cement mixing piles.
6. The deep foundation pit supporting structure according to claim 1, wherein the interval between adjacent cast-in-place piles is 100-200 mm.
7. The deep foundation pit supporting structure of claim 1, wherein the radial overlap length between the high pressure jet grouting pile and the cast-in-place pile is 100-150 mm.
8. The deep foundation pit supporting structure according to claim 1, wherein the distance between the steel sheet pile enclosure and the high-pressure jet grouting pile enclosure is 50-100 mm.
9. The deep foundation pit supporting structure according to claim 1, wherein the foundation pit inner support comprises a transverse inner support and a longitudinal inner support, the transverse inner support and the longitudinal inner support are vertically arranged, two ends of the transverse inner support respectively abut against two different sides of the cast-in-place pile enclosure, two ends of the longitudinal inner support also respectively abut against two different sides of the cast-in-place pile enclosure, the lower parts of the plurality of steel pipe piles are respectively inserted into the ground, and the upper parts of the plurality of steel pipe piles are respectively located at the connecting node positions of the transverse inner support and the longitudinal inner support and are used for supporting the transverse inner support and the longitudinal inner support.
10. A method of constructing a deep foundation pit supporting structure according to any one of claims 1 to 9, comprising the steps of:
1) cleaning and leveling a ground of a foundation pit to be excavated;
2) paying off and positioning the positions of the first cement mixing pile, the second cement mixing pile, the cast-in-place pile and the steel pipe pile according to the construction drawing;
3) constructing a first cement mixing pile: arranging a plurality of circles of first cement mixing piles around the outer side of the foundation pit according to the paying-off position, and constructing the cement mixing piles to the designed depth;
4) constructing a second cement mixing pile: arranging a plurality of rows of second cement mixing piles at equal intervals on the inner side of the foundation pit according to the setting-out position, and constructing the second cement mixing piles to the designed depth;
5) constructing the steel pipe pile: arranging a plurality of steel pipe piles on the inner side of the foundation pit according to the paying-off position, and constructing the steel pipe piles to the designed depth;
6) constructing a cast-in-place pile: arranging a circle of cast-in-place piles around the periphery of the foundation pit according to the paying-off position, constructing the cast-in-place piles to the designed depth, and enabling the intervals between the adjacent cast-in-place piles to be equal;
7) after the construction of the cast-in-place piles is finished, constructing a high-pressure jet grouting pile between two adjacent cast-in-place piles to the designed depth along the circumferential outer sides of the cast-in-place piles;
8) after the high-pressure jet grouting pile is constructed, constructing a steel sheet pile to a designed depth along the circumferential outer side of the high-pressure jet grouting pile by a specified distance;
9) excavating foundation soil in an area surrounded by the innermost first cement mixing pile in a subsection and layer-by-layer mode according to design requirements, and meanwhile, erecting a supporting ring beam and a foundation pit inner support on a cast-in-place pile layer by layer from top to bottom;
10) and after the last layer of support ring beam and the foundation pit inner support are erected, continuously excavating the foundation pit to the top surface of the second cement mixing pile.
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| CN111980063A (en) * | 2020-08-17 | 2020-11-24 | 济南轨道交通集团有限公司 | Subway open cut interval prefabricated box culvert laminated structure and construction method thereof |
| CN112195922A (en) * | 2020-09-07 | 2021-01-08 | 济南市市政工程设计研究院（集团）有限责任公司 | Foundation pit construction method suitable for weak underlying layer |
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| CN114232638A (en) * | 2021-11-30 | 2022-03-25 | 中交路桥建设有限公司 | Anchorage supporting construction |
| CN117211289A (en) * | 2023-11-08 | 2023-12-12 | 中国建筑第六工程局有限公司 | Construction method of multiple systems of foundation in complex environment |
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