CN114086566B - Long and narrow soft soil foundation pit excavation support and soil transportation method - Google Patents
Long and narrow soft soil foundation pit excavation support and soil transportation method Download PDFInfo
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- CN114086566B CN114086566B CN202111327669.8A CN202111327669A CN114086566B CN 114086566 B CN114086566 B CN 114086566B CN 202111327669 A CN202111327669 A CN 202111327669A CN 114086566 B CN114086566 B CN 114086566B
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- foundation pit
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D17/00—Excavations; Bordering of excavations; Making embankments
- E02D17/02—Foundation pits
- E02D17/04—Bordering surfacing or stiffening the sides of foundation pits
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—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
- E02F—DREDGING; SOIL-SHIFTING
- E02F7/00—Equipment for conveying or separating excavated material
- E02F7/02—Conveying equipment mounted on a dredger
- E02F7/026—Conveying equipment mounted on a dredger mounted on machines equipped with dipper- or bucket-arms
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- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
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- Civil Engineering (AREA)
- General Engineering & Computer Science (AREA)
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Abstract
The invention discloses a long and narrow type soft soil foundation pit excavation supporting and soil body transportation method, which comprises the following steps: leveling a field, backfilling brick residues to form an operation surface, constructing cement mixing piles and pipe piles in a passive area, and constructing foundation pit supporting piles; removing hard shell layers such as brick slag, surface filling and the like by using an excavator, and constructing a first cross brace; inserting a screw conveyor into the soft soil with the hard shell layer removed, and conveying the soft soil to a collecting hopper through the screw conveyor; the end part of the spiral conveyor is matched with manual insertion vibration, so that the upper soil body can be ensured to sink continuously, and a supporting system is applied in time; when the excavation is close to the bottom of the foundation pit, a small excavator and manual excavation are matched; soft soil is unloaded to a transport vehicle through a material collecting hopper, and the material collecting hopper is arranged in a hard shell area outside an excavation range. The invention avoids the operation of large excavating machinery and transport vehicles on the top of the foundation pit, ensures the safety of the foundation pit and reduces the use of large excavating machinery.
Description
Technical Field
The invention relates to a foundation pit construction method, in particular to a long and narrow type soft soil foundation pit excavation supporting and soil body transportation method.
Background
In the traditional excavation method for the long and narrow foundation pit, a long-arm excavator is generally adopted to directly excavate soil at the top of the foundation pit downwards, then the soil is loaded at the top of the foundation pit through a transport vehicle, and the excavated soil is transported to a specified place through a construction access at the top of the foundation pit, as shown in fig. 1. The traditional excavation mode causes the extremely big dynamic load at the top of the foundation pit, and in soft soil areas, the foundation pit often deforms greatly, so that the damage to the adjacent underground pipelines is caused. The soft soil has strong structurality, the shear strength of the soil body can be reduced by 3-4 times under the action of dynamic load, and a transport vehicle runs at the top of a soft soil foundation pit, thereby causing serious threat to the safety of the foundation pit. Relevant scholars and engineering technicians carry out certain research aiming at the problems, and a patent CN 109533859B proposes 'a conveying belt conveying excavation conveying method', but conveying equipment is still arranged at the top of a foundation pit, the load of a conveying vehicle on the top of the foundation pit is not reduced, and the equipment installation position is fixed, so that the conveying belt conveying excavation conveying method is not suitable for excavation of the foundation pit with the length of several kilometers, such as a comprehensive pipe gallery.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a long and narrow soft soil foundation pit excavation support and a soil body transportation method which avoid additional load of construction machinery and transportation vehicles on the top of an excavated foundation pit.
In order to realize the purpose, the invention adopts the technical scheme that:
the invention relates to a long and narrow soft soil foundation pit excavation supporting and soil body transportation method, which comprises the following steps:
step a, leveling a field, and backfilling brick slag to form a hard shell layer operation surface; then constructing a passive area cement mixing pile and a pipe pile in the to-be-excavated foundation pit area, and finally constructing foundation pit supporting piles around the to-be-excavated foundation pit area;
b, performing core pulling detection after the cement mixing pile reaches the age of 28d, continuously and completely using a core sample and the compressive strength of the core sample is not less than 0.8MPa, excavating part of a hard shell layer on the top surface of the foundation pit by using an excavator after the cement mixing pile is detected to be qualified, and installing a first cross brace on the upper part in the foundation pit when the excavation depth reaches 0.5-1.0 m;
c, inserting the screw conveyor into the soft soil layer with the hard shell layer excavated, wherein the insertion depth is 1.0-2.0 m, the end, inserted into the soft soil, of the screw conveyor is provided with a cutter head, starting the screw conveyor, cutting the soil body by the cutter head and conveying the soil body to a collecting hopper through the screw conveyor, and the collecting hopper continuously retreats along with excavation of the foundation pit and is always positioned on the hard shell layer;
d, manually inserting and vibrating the end part of the spiral conveyor inserted into the soil body, wherein the length of a vibrating rod is 1.0-1.5 m, so that the upper soil body cut by the spiral conveyor can sink and be dense continuously, when the top surface elevation of the soil body in the foundation pit is reduced to be 0.5m below the design elevation of a second support, the earthwork excavation of the foundation pit is suspended, and the second cross support is installed at the design elevation of the second support in the foundation pit;
e, repeatedly repeating the step d to continue excavation of the earthwork of the foundation pit and respectively installing each cross brace at each support design elevation in the foundation pit, when the excavation is 0.5m above the bottom of the foundation pit, adopting an excavator to send the soft soil at the corners inside the foundation pit to a screw conveyor, and when the excavation reaches 0.3m above the bottom of the foundation pit, adopting manual bottom cleaning to send the soft soil to a collecting hopper through the conveyor;
f, unloading the soft soil to a transport vehicle through a collecting hopper, driving the transport vehicle to enter a hard shell layer region inside the foundation pit for loading the soil on the side edge of the foundation pit which is not excavated, driving the transport vehicle for a distance on the hard shell layer region inside the foundation pit which is not excavated, then entering a construction access way on the side edge of the foundation pit, and transporting the excavated soft soil to a specified place;
and g, excavating a next section of hard shell layer on the top surface of the foundation pit according to the step b, and then repeating the step b-the step g until the excavation of all the foundation pits is completed.
Compared with the prior art, the invention has the following obvious advantages:
1. the invention does not need a long-arm excavating machine to operate at the top of the foundation pit, avoids overload at the top of the foundation pit, reduces deformation and stress concentration of the foundation pit, and effectively ensures the safety of the foundation pit.
2. The invention does not need a transport vehicle to load and transport soil at the top of the foundation pit, thereby avoiding the structural damage and strength reduction of soft soil caused by dynamic load at the top of the foundation pit.
3. The invention can realize continuous line production, the transport vehicle does not need to wait for too long time on site, the construction efficiency is obviously improved compared with the excavation mode of a long-arm excavator at the top of the foundation pit, and the construction period can be greatly shortened.
4. The construction method has the advantages of less construction investment personnel and good economy, and can greatly save the construction cost of earth excavation in the soft soil area.
Drawings
FIG. 1 is a construction drawing of a commonly used method for excavating a long and narrow foundation pit;
FIG. 2 is a construction schematic diagram of step a in the method of the present invention;
FIG. 3 is a schematic view of an excavation plane of an elongated foundation pit;
FIG. 4 is a right side view in transverse section of the structure of FIG. 3, which is a schematic illustration of the construction of step b of the method of the present invention;
FIG. 5 is a longitudinal cross-sectional view of the structure of FIG. 3, schematically illustrating the operation of step c of the method of the present invention;
FIG. 6 is a schematic illustration of the construction of step d in the method of the present invention;
FIG. 7 is a schematic illustration of the construction of step e in the method of the present invention;
FIG. 8 is a construction schematic of step f in the method of the present invention.
Detailed Description
The invention will be further illustrated with reference to the following specific examples. These examples are intended to illustrate the invention and are not intended to limit the scope of the invention. In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "provided with" and "connected" are to be interpreted broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
As shown in the attached drawings, the invention discloses a long and narrow soft soil foundation pit excavation supporting and soil body transportation method, which comprises the following steps:
step a, leveling a field, backfilling brick slag to form a hard shell layer working surface 1, wherein the thickness of the preferred hard shell layer is 1.0-2.0 m (such as 1.0m, 1.5m and 2.0 m); then constructing a cement mixing pile 4 and a tubular pile 5 in a passive area in the area of the foundation pit to be excavated, and finally constructing foundation pit supporting piles 6 around the area of the foundation pit to be excavated; the construction of the cement mixing pile 4, the tubular pile 5 and the supporting pile 6 in the passive area can be realized by adopting the existing method.
B, performing core pulling detection after the cement mixing pile reaches the age of 28d, continuously and completely using a core sample and the compressive strength of the core sample is not less than 0.8MPa, excavating partial hard shell layers (brick slag, surface filling soil and the like) on the top surface of the foundation pit by using an excavator 7 after the cement mixing pile is detected to be qualified, and installing a first cross brace 8 at the upper part in the foundation pit when the excavation depth reaches 0.5-1.0 m (for example, 0.5m, 0.8m and 1.0 m);
step c, inserting the screw conveyor 9 into the soft soil layer 2 with the hard shell layer excavated, wherein the insertion depth is 1.0-2.0 m (for example, the insertion depth can be 1.0m, 1.5m and 2.0 m), one end of the screw conveyor inserted into the soft soil is provided with a cutter head, starting the screw conveyor, the cutter head starts to cut the soil body and conveys the soil body to a collecting hopper 10 through the screw conveyor, and the collecting hopper 10 continuously retreats along with the excavation of the foundation pit and is always positioned on the hard shell layer;
d, manually inserting vibration 12 into the end part of the spiral conveyor inserted with the soil body, wherein the length of a vibration rod is 1.0-1.5 m (for example, the length can be 1.0m, 1.2m and 1.5 m), the upper soil body cut by the spiral conveyor can be ensured to be continuously sunk and compacted, when the top surface elevation of the soil body in the foundation pit is reduced to 0.5m below the design elevation of a second support, the excavation of the earthwork of the foundation pit is suspended, and the second cross support is arranged at the design elevation of the second support in the foundation pit;
e, repeatedly repeating the step d to continue excavation of the earthwork of the foundation pit and respectively installing each cross brace at each support design elevation in the foundation pit, when the excavation reaches 0.5m above the bottom of the foundation pit, sending the soft soil 2 at the corner inside the foundation pit to a spiral conveyor by using an excavator 72, and when the excavation reaches 0.3m above the bottom of the foundation pit, sending the soft soil to a collecting hopper by using a conveyor for manual bottom cleaning;
f, unloading the soft soil to a transport vehicle 11 through a collecting hopper 10, enabling the transport vehicle to drive at the side edge of the foundation pit which is not excavated to enter a hard shell layer region inside the foundation pit for loading the soil, then driving for a distance at the hard shell layer region which is not excavated inside the foundation pit, then enabling the transport vehicle to enter a construction access way at the side edge of the foundation pit, and transporting the excavated soft soil to a specified place;
and g, excavating a next section of hard shell layer on the top surface of the foundation pit according to the step b, and then repeating the step b-the step g until the excavation of all the foundation pits is completed.
The method comprises the following steps: the foundation pit is characterized in that brick slag and other high-strength backfill materials are backfilled into the interior of the foundation pit to form a hard shell layer, the hard shell layer is used for forming an operation platform for operation of construction machinery such as a stirring pile, a tubular pile, a spiral conveyor and a collecting hopper, and the bearing capacity of the hard shell layer is determined by design or calculation and is not less than 80kPa.
When soft soil intensity is higher, the end part of the spiral conveyor inserted into the soil body is matched with manual insertion vibration, the soil body after cutting is prevented from forming a soil arch effect, and the upper soil body after the spiral conveyor is cut can be guaranteed to be continuously sunk and compacted.
When the top surface elevation of the soil body inside the foundation pit is reduced to 0.5m below the design elevations of the second cross brace, the third cross brace and the like, earthwork excavation is suspended, a supporting system is installed in time, influence on the safety of the foundation pit is avoided when the upper brace is untimely, when the height is close to 0.5m above the bottom of the foundation pit, a small excavator is matched to send the soft soil at the corner to a screw conveyor inside the foundation pit, when the height reaches 0.3m above the bottom of the foundation pit, manual bottom clearing is adopted to send the soft soil to a collecting hopper through the conveyor, and the phenomenon that a cutter disc overedges and disturbs the soil body below the design elevation of the bottom of the foundation pit is avoided.
Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described above, or equivalents may be substituted for elements thereof. 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 (2)
1. A long and narrow soft soil foundation pit excavation supporting and soil body transportation method is characterized by comprising the following steps:
step a, leveling a field, and backfilling brick slag to form a hard shell layer operation surface; then constructing a passive area cement mixing pile and a pipe pile in the area of the foundation pit to be excavated, and finally constructing foundation pit support piles around the area of the foundation pit to be excavated;
b, performing core-pulling detection after the cement mixing pile reaches the age of 28d, continuously and completely testing a core sample, wherein the compressive strength is not less than 0.8MPa, excavating partial hard shell layer on the top surface of the foundation pit by using an excavator after the cement mixing pile is qualified, and installing a first cross brace on the upper part in the foundation pit when the excavation depth reaches 0.5-1.0 m;
c, inserting the screw conveyor into the soft soil layer with the hard shell layer excavated, wherein the insertion depth is 1.0-2.0 m, the end, inserted into the soft soil, of the screw conveyor is provided with a cutter head, starting the screw conveyor, cutting the soil body by the cutter head and conveying the soil body to a collecting hopper through the screw conveyor, and the collecting hopper continuously retreats along with excavation of the foundation pit and is always positioned on the hard shell layer;
d, manually inserting and vibrating the end part of the spiral conveyor, which is inserted into the soil body, wherein the length of a vibrating rod is 1.0-1.5 m, so that the upper soil body cut by the spiral conveyor can sink continuously and tightly, when the top surface elevation of the soil body in the foundation pit is reduced to 0.5m below the design elevation of a second support, the excavation of the earthwork of the foundation pit is suspended, and the second cross support is arranged at the design elevation of the second support in the foundation pit;
e, repeatedly repeating the step d to continue excavation of the earthwork of the foundation pit and respectively installing each cross brace at each support design elevation in the foundation pit, when the excavation is 0.5m above the bottom of the foundation pit, adopting an excavator to send the soft soil at the corners inside the foundation pit to a screw conveyor, and when the excavation reaches 0.3m above the bottom of the foundation pit, adopting manual bottom cleaning to send the soft soil to a collecting hopper through the conveyor;
f, unloading the soft soil to a transport vehicle through a collecting hopper, driving the transport vehicle to enter a hard shell layer region inside the foundation pit for loading the soil on the side edge of the foundation pit which is not excavated, driving the transport vehicle for a distance on the hard shell layer region inside the foundation pit which is not excavated, then entering a construction access way on the side edge of the foundation pit, and transporting the excavated soft soil to a specified place;
and g, excavating a next section of hard shell layer on the top surface of the foundation pit according to the step b, and then repeating the step b-the step g until the excavation of all the foundation pits is completed.
2. The long and narrow soft soil foundation pit excavation supporting and soil body transporting method according to claim 1, wherein: the thickness of the hard shell layer is 1.0-2.0 m.
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| CN202111327669.8A CN114086566B (en) | 2021-11-10 | 2021-11-10 | Long and narrow soft soil foundation pit excavation support and soil transportation method |
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| CN202111327669.8A CN114086566B (en) | 2021-11-10 | 2021-11-10 | Long and narrow soft soil foundation pit excavation support and soil transportation method |
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| CN114086566B true CN114086566B (en) | 2023-01-17 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP4173161B2 (en) * | 2005-12-28 | 2008-10-29 | 東日本旅客鉄道株式会社 | Excavation and excavation equipment for narrow spaces, excavation and excavation method and excavation and soil removal system for narrow areas |
| CN103410152B (en) * | 2013-09-05 | 2015-08-19 | 中交公路养护工程技术有限公司 | A kind of construction method for long and narrow deep foundation pit earthwork digging |
| CN106759366B (en) * | 2017-01-25 | 2018-10-09 | 北京市政建设集团有限责任公司 | The construction method of soil excavation and riding track arrangement in a kind of foundation pit |
| CN108343067B (en) * | 2018-02-11 | 2020-02-07 | 宁波市明耀智能科技有限公司 | Method for excavating foundation pit on soft soil with water content of more than 60 percent |
| CN110295605A (en) * | 2018-03-23 | 2019-10-01 | 周兆弟 | A kind of foundation pit structure and its construction method |
| CN110158603A (en) * | 2019-06-14 | 2019-08-23 | 北京翔鲲水务建设有限公司 | Long and narrow deep foundation pit earthwork digging method |
| CN110219304B (en) * | 2019-06-27 | 2021-04-06 | 云南建投第十二建设有限公司 | Foundation pit excavation method for soft plastic land |
| CN213390195U (en) * | 2020-08-26 | 2021-06-08 | 中铁第五勘察设计院集团有限公司 | Foundation structure |
| CN112227380A (en) * | 2020-10-16 | 2021-01-15 | 民航机场规划设计研究总院有限公司 | Foundation pit support and foundation treatment synergistic effect method, structure and underground structure construction method |
| CN112323819A (en) * | 2020-12-05 | 2021-02-05 | 中铁四院集团广州设计院有限公司 | Soft soil foundation pit bottom in-situ curing method and soft soil foundation pit bottom curing structure |
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