CN110195438B - Ultra-deep foundation pit construction method for foundation edge under narrow space condition - Google Patents
Ultra-deep foundation pit construction method for foundation edge under narrow space condition Download PDFInfo
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- CN110195438B CN110195438B CN201910518598.6A CN201910518598A CN110195438B CN 110195438 B CN110195438 B CN 110195438B CN 201910518598 A CN201910518598 A CN 201910518598A CN 110195438 B CN110195438 B CN 110195438B
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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
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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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Abstract
The invention discloses a construction method of an ultra-deep foundation pit with a foundation edge under a narrow space condition, which comprises the following steps: measuring and paying off according to the position of an original foundation bearing platform, and determining the excavation position of the ultra-deep foundation pit; determining the arrangement condition of an underground original foundation bearing platform at the excavation position of the ultra-deep foundation pit, wherein the arrangement condition comprises the step of reinforcing the original foundation bearing platform positioned at the adjacent edge of the excavation position of the ultra-deep foundation pit; and excavating earthwork in the ultra-deep foundation pit. The technical scheme of the invention can ensure the stability of the original foundation bearing platform structure and effectively solve the problem that the ultra-deep foundation pit in the prior art is difficult to construct under the condition of narrow space.
Description
Technical Field
The invention belongs to the technical field of earth excavation, and particularly relates to a construction method of an ultra-deep foundation pit at the edge of a foundation under a narrow space condition.
Background
In the prior art, when the field space is narrow, the ultra-deep foundation pit is excavated near the edge of the original foundation bearing platform, slope excavation cannot be carried out, and the original foundation bearing platform is easily damaged in the construction process.
Disclosure of Invention
The invention mainly aims to provide a construction method of an ultra-deep foundation pit at the adjacent edge of a foundation under a narrow space condition, so as to solve the problem that the ultra-deep foundation pit is difficult to construct under the narrow space condition in the prior art.
In order to achieve the purpose, the invention provides a construction method of an ultra-deep foundation pit with a foundation edge under a narrow space condition, which comprises the following steps: measuring and paying off according to the position of an original foundation bearing platform, and determining the excavation position of the ultra-deep foundation pit; determining the arrangement condition of an underground original foundation bearing platform at the excavation position of the ultra-deep foundation pit, wherein the arrangement condition comprises the step of reinforcing the original foundation bearing platform positioned at the adjacent edge of the excavation position of the ultra-deep foundation pit; and excavating earthwork in the ultra-deep foundation pit.
Further, the step of determining the excavation position of the ultra-deep foundation pit comprises the step of determining the position of an original foundation cap according to an original design drawing.
Further, in the step of reinforcing the original foundation bearing platform located at the edge of the excavation position of the ultra-deep foundation pit, the construction method of the ultra-deep foundation pit further comprises the following steps:
making an artificial pore-forming cast-in-place pile below the original foundation bearing platform;
embedding an anchor cable in a soil layer on the side wall of the ultra-deep foundation pit;
forming the cast-in-place pile and the anchor cable into a whole to bear force together through the connecting beam;
and coating concrete on the surface of the soil layer on the side wall of the ultra-deep foundation pit.
Furthermore, in the step of manufacturing the artificial pore-forming cast-in-place pile below the original foundation bearing platform, one half of the cast-in-place pile is positioned below the original foundation bearing platform, and the other half of the cast-in-place pile is positioned outside the original foundation bearing platform so as to be transported outside the excavated earthwork.
Further, in the step of manufacturing the artificial hole-forming cast-in-place pile under the original foundation bearing platform, the construction method of the ultra-deep foundation pit further comprises the steps of cleaning sediment at the bottom of the hole and carrying out formwork support and wall protection treatment on the hole wall.
Further, in the step of performing formwork supporting and wall protecting treatment on the hole wall, the construction method of the ultra-deep foundation pit further comprises the following steps:
adopting a wood plate formwork and a steel hoop to perform formwork supporting and wall protecting;
binding a reinforcement cage in the hole;
cleaning the sediment at the bottom of the hole again;
commercial concrete is adopted for pouring.
Further, in the step of embedding the anchor cable in the soil layer of the side wall of the ultra-deep foundation pit, the construction method of the ultra-deep foundation pit further comprises the following steps:
arranging anchor cables;
forming holes in the anchor cable;
and (6) mounting an anchor cable and grouting.
Further, in the step of arranging the anchor cables, the construction method of the ultra-deep foundation pit further comprises arranging one anchor cable between every two cast-in-place piles in the horizontal direction; in the height direction, the first path is downward 4m from the top of the through beam, and the rest paths are downward every 2m in sequence for 3 paths; each anchor cable is 18m in length, and the anchor cable and the horizontal plane form an included angle of 15-20 degrees and are anchored into the soil downwards. The anchor cable penetrates through the middle of the connecting beam and is connected with the row piles into a whole to be stressed together.
Further, in the step of forming the hole by the anchor cable, the construction method of the ultra-deep foundation pit further comprises the step of forming the hole at the anchor cable position by a drilling machine, wherein the hole diameter phi is 200, when the hole is drilled, the drill rod required by drilling is placed in order according to the designed length of the anchor cable, the drill rod is used up, and the hole depth is just in place. The inclined angle of the anchor cable hole and the horizontal plane is preferably between 15 and 20 degrees, the allowable error is +/-1 degree, and the drilling depth exceeds the designed length of the anchor cable by about 0.5 m. And after drilling, pulling out the drill rod and the drilling tool one by one, and cleaning the impacter for later use.
Further, in the anchor cable installation and grouting step, the ultra-deep foundation pit construction method further comprises the steps of inserting steel pipes with the same diameter into the hole after the drill bit is taken out, then inserting 3 steel wire ropes with phi 21.5 and phi 40PE pipes for grouting into the anchor cable hole through the steel pipes together, and pulling out the steel pipes after the specified depth is reached; and (2) pouring cement mortar from the bottom of the hole to the outside through a movable grouting pipe (the specific requirements are that the water cement ratio is 0.4-0.45 and the cement-sand ratio is 1: 1), inserting the grouting pipe to the bottom of the hole during grouting, injecting the mortar from the bottom of the hole, discharging air from the anchor cable hole, adopting a grouting machine for grouting, keeping the grouting pressure at 0.3-0.6 MPa, adopting a mortar position indicator to control the grouting position, stopping when a large amount of slurry flows out from the hole opening, and drawing out the grouting pipe.
By applying the technical scheme of the invention, the distribution condition of the original foundation bearing platform under the ground is confirmed before the ultra-deep foundation pit is excavated, and cast-in-place pile reinforcement is firstly carried out on the original foundation bearing platform close to the ultra-deep foundation pit in the excavation process, so that the original foundation bearing platform is effectively prevented from being damaged, the stability of the original foundation bearing platform structure is ensured, and the ultra-deep foundation pit construction can be smoothly carried out.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 shows a flow chart of an embodiment of the method for constructing the ultra-deep foundation pit of the foundation bordering on the narrow space condition according to the invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
It is noted that, unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
In the present invention, unless stated to the contrary, use of the terms of orientation such as "upper, lower, top, bottom" or the like, generally refer to the orientation as shown in the drawings, or to the orientation as such, whether vertical, perpendicular, or gravitational; also, for ease of understanding and description, "inner and outer" are inner and outer relative to the profile of the respective component itself, but the above directional words are not intended to limit the invention.
The invention provides a construction method of an ultra-deep foundation pit near the edge of a foundation under a narrow space condition, aiming at solving the problem that the construction of the ultra-deep foundation pit under the narrow space condition in the prior art is difficult.
As shown in fig. 1, the method for constructing an ultra-deep foundation pit at a foundation edge under a narrow space condition in the embodiment of the present application includes: measuring and paying off according to the position of an original foundation bearing platform, and determining the excavation position of the ultra-deep foundation pit; determining the arrangement condition of an underground original foundation bearing platform at the excavation position of the ultra-deep foundation pit, wherein the arrangement condition comprises the step of reinforcing the original foundation bearing platform positioned at the adjacent edge of the excavation position of the ultra-deep foundation pit; and excavating earthwork in the ultra-deep foundation pit.
In this embodiment, the step of determining the excavation position of the ultra-deep foundation pit includes determining the position of the original foundation cap based on the original design drawing.
In this embodiment, in the step of reinforcing the original foundation cap located at the edge of the excavation position of the ultra-deep foundation pit, the method for constructing the ultra-deep foundation pit further includes: making an artificial pore-forming cast-in-place pile below the original foundation bearing platform; embedding an anchor cable in a soil layer on the side wall of the ultra-deep foundation pit; forming the cast-in-place pile and the anchor cable into a whole to bear force together through the connecting beam; and coating concrete on the surface of the soil layer on the side wall of the ultra-deep foundation pit.
In this embodiment, further, in the step of forming the artificial pore-forming cast-in-place pile under the original foundation cap, one half of the cast-in-place pile is located under the original foundation cap, and the other half is located outside the original foundation cap so as to be transported out of the excavated earth.
In this embodiment, in the step of forming the artificial bored pile under the original foundation cap, the method for constructing the ultra-deep foundation pit further includes cleaning up the sediment at the bottom of the hole, and performing formwork support and wall protection treatment on the hole wall.
In this embodiment, in the step of performing formwork supporting and wall protecting treatment on the hole wall, the ultra-deep foundation pit construction method further includes: adopting a wood plate formwork and a steel hoop to perform formwork supporting and wall protecting; binding a reinforcement cage in the hole; cleaning the sediment at the bottom of the hole again; commercial concrete is adopted for pouring.
In this embodiment, in the step of burying the anchor cable in the soil layer of the sidewall of the ultra-deep foundation pit, the method for constructing the ultra-deep foundation pit further includes: arranging anchor cables; forming holes in the anchor cable; and (6) mounting an anchor cable and grouting.
In this embodiment, in the step of arranging the anchor cables, the construction method of the ultra-deep foundation pit further includes arranging one anchor cable between every two cast-in-place piles in the horizontal direction; in the height direction, the first path is downward 4m from the top of the through beam, and the rest paths are downward every 2m in sequence for 3 paths; each anchor cable is 18m in length, and the anchor cable and the horizontal plane form an included angle of 15-20 degrees and are anchored into the soil downwards. The anchor cable penetrates through the middle of the connecting beam and is connected with the row piles into a whole to be stressed together.
In this embodiment, in the step of forming the hole by the anchor cable, the method for constructing the ultra-deep foundation pit further includes forming a hole at the anchor cable position by using a drilling machine, wherein the hole diameter Φ 200 is obtained, when drilling, the drill rods required for drilling are placed in order according to the designed length of the anchor cable, and the drill rods are used up, so that the hole depth is just in place. The inclined angle of the anchor cable hole and the horizontal plane is preferably between 15 and 20 degrees, the allowable error is +/-1 degree, and the drilling depth exceeds the designed length of the anchor cable by about 0.5 m. And after drilling, pulling out the drill rod and the drilling tool one by one, and cleaning the impacter for later use.
In the embodiment, in the anchor cable installation and grouting step, the ultra-deep foundation pit construction method further comprises the steps of inserting steel pipes with the same diameter into the hole after the drill bit is taken out, then inserting 3 steel wire ropes with phi 21.5 and phi 40PE pipes for grouting into the anchor cable hole through the steel pipes together, and pulling out the steel pipes after the specified depth is reached; and (2) pouring cement mortar from the bottom of the hole to the outside through a movable grouting pipe (the specific requirements are that the water cement ratio is 0.4-0.45 and the cement-sand ratio is 1: 1), inserting the grouting pipe to the bottom of the hole during grouting, injecting the mortar from the bottom of the hole, discharging air from the anchor cable hole, adopting a grouting machine for grouting, keeping the grouting pressure at 0.3-0.6 MPa, adopting a mortar position indicator to control the grouting position, stopping when a large amount of slurry flows out from the hole opening, and drawing out the grouting pipe.
From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects: before the ultra-deep foundation pit excavation, confirm the distribution condition of former basic cushion cap in the subsurface, at the excavation in-process, carry out the bored concrete pile earlier and consolidate the former basic cushion cap that closes on the ultra-deep foundation pit, prevent effectively that former basic cushion cap from being damaged, guaranteed the stability of former basic cushion cap structure, make the ultra-deep foundation pit construction go on smoothly.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A construction method of an ultra-deep foundation pit with a foundation edge under a narrow space condition is characterized by comprising the following steps:
measuring and paying off according to the position of an original foundation bearing platform, and determining the excavation position of the ultra-deep foundation pit;
determining the arrangement condition of an underground original foundation bearing platform at the ultra-deep foundation pit excavation position, wherein the arrangement condition comprises the step of reinforcing the original foundation bearing platform positioned at the adjacent edge of the ultra-deep foundation pit excavation position;
excavating earthwork in the ultra-deep foundation pit;
in the step of reinforcing the original foundation bearing platform located at the edge of the excavation position of the ultra-deep foundation pit, the construction method of the ultra-deep foundation pit further comprises the following steps:
making an artificial pore-forming cast-in-place pile below the original foundation bearing platform;
embedding an anchor cable in a soil layer on the side wall of the ultra-deep foundation pit;
forming the cast-in-place pile and the anchor cable into a whole to bear force together through a connecting beam;
coating concrete on the surface of the soil layer on the side wall of the ultra-deep foundation pit;
in the step of manufacturing the artificial pore-forming cast-in-place pile below the original foundation bearing platform, one half of the cast-in-place pile is positioned below the original foundation bearing platform, and the other half of the cast-in-place pile is positioned outside the original foundation bearing platform so as to facilitate the outward transportation of excavated earthwork;
in the step of making the artificial pore-forming cast-in-place pile under the original foundation bearing platform, the construction method of the ultra-deep foundation pit further comprises the steps of cleaning hole bottom sediment and carrying out formwork support and wall protection treatment on a hole wall;
in the step of performing formwork supporting and wall protecting treatment on the hole wall, the construction method of the ultra-deep foundation pit further comprises the following steps:
adopting a wood plate formwork and a steel hoop to perform formwork supporting and wall protecting;
binding a reinforcement cage in the hole;
cleaning the sediment at the bottom of the hole again;
commercial concrete is adopted for pouring.
2. The ultra-deep foundation pit construction method according to claim 1, wherein the step of determining the excavation position of the ultra-deep foundation pit comprises determining the position of an original foundation cap based on an original design drawing.
3. The ultra-deep foundation pit construction method according to claim 1, wherein in the step of burying anchor cables in the ultra-deep foundation pit sidewall soil layer, the ultra-deep foundation pit construction method further comprises:
arranging anchor cables;
forming holes in the anchor cable;
and (6) mounting an anchor cable and grouting.
4. The ultra-deep foundation pit construction method according to claim 3, wherein in the anchor cable arrangement step, the ultra-deep foundation pit construction method further comprises arranging one anchor cable between every two cast-in-place piles in the horizontal direction; in the height direction, the first path is 4m downwards from the top of the crown beam, and the rest paths are downwards sequentially one path every 2m, and the total number is 3; each anchor cable is 18m in length, an included angle between the anchor cable and the horizontal plane is 15-20 degrees, the anchor cable is downwards anchored into the soil, and the anchor cable penetrates through the middle of the connecting beam and is connected with the cast-in-place pile into a whole to be stressed together.
5. The ultra-deep foundation pit construction method according to claim 3, wherein in the anchor cable hole forming step, the ultra-deep foundation pit construction method further comprises the step of forming a hole at the anchor cable position by using a drilling machine, wherein the hole diameter phi 200 is obtained, during drilling, the drill rod required for drilling is placed in order according to the designed length of the anchor cable, the drill rod is used up, the hole depth is just in place, the included angle between the anchor cable hole and the horizontal plane is 15-20 degrees, the allowable error is +/-1 degree, the drilling depth exceeds the designed length of the anchor cable by about 0.5m, the drill rod and the drilling tool are pulled out one by one after the drilling is finished, and the impacter is cleaned for later use.
6. The ultra-deep foundation pit construction method according to claim 3, wherein in the anchor cable installation and grouting step, the ultra-deep foundation pit construction method further comprises inserting steel pipes of the same diameter into the holes after the drill bit is taken out, then inserting the 3 steel wire ropes of phi 21.5 and phi 40PE pipes for grouting into the anchor cable holes through the steel pipes together, and pulling out the steel pipes after reaching a specified depth; the grouting is performed by pouring cement mortar from the bottom of the hole to the outside through a movable grouting pipe, and the concrete requirements are as follows: the water-cement ratio is 0.4-0.45, and the sand-lime ratio is 1: 1, during grouting, inserting a grouting pipe to the bottom of a hole, injecting mortar from the bottom of the hole, discharging air from an anchor cable hole, adopting a grouting machine for grouting, keeping grouting pressure at 0.3-0.6 MPa, controlling a grouting position by adopting a mortar position indicator, stopping grouting when a large amount of mortar flows out of an orifice, and drawing out the grouting pipe.
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Citations (2)
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| CN106759442A (en) * | 2017-01-05 | 2017-05-31 | 中建三局第二建设工程有限责任公司 | A kind of single-pile elevated bearing-platform and anchor cable tower-crane foundation structure and its construction method |
| CN107447765A (en) * | 2017-05-24 | 2017-12-08 | 四川君羊建设集团有限公司 | Side slope construction supported with framed anchor construction |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106759442A (en) * | 2017-01-05 | 2017-05-31 | 中建三局第二建设工程有限责任公司 | A kind of single-pile elevated bearing-platform and anchor cable tower-crane foundation structure and its construction method |
| CN107447765A (en) * | 2017-05-24 | 2017-12-08 | 四川君羊建设集团有限公司 | Side slope construction supported with framed anchor construction |
Non-Patent Citations (2)
| Title |
|---|
| 受限空间条件下高速公路桥桩基加固技术研究;张德波;《建筑技术开发》;20190225;第46卷(第4期);第1-3节 * |
| 张德波.受限空间条件下高速公路桥桩基加固技术研究.《建筑技术开发》.2019,第46卷(第4期),第1-3节. * |
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