CN110777823A - Flexible net surface layer and rigid beam composite soil nailing wall supporting system - Google Patents
Flexible net surface layer and rigid beam composite soil nailing wall supporting system Download PDFInfo
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- CN110777823A CN110777823A CN201911146288.2A CN201911146288A CN110777823A CN 110777823 A CN110777823 A CN 110777823A CN 201911146288 A CN201911146288 A CN 201911146288A CN 110777823 A CN110777823 A CN 110777823A
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- surface layer
- slope
- soil
- rigid beam
- flexible net
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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
- E02D17/20—Securing of slopes or inclines
-
- 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
-
- 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
- E02D17/20—Securing of slopes or inclines
- E02D17/202—Securing of slopes or inclines with flexible securing means
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- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Paleontology (AREA)
- Civil Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Structural Engineering (AREA)
- Pit Excavations, Shoring, Fill Or Stabilisation Of Slopes (AREA)
Abstract
The invention relates to a composite soil nailing wall supporting system of a flexible net surface layer and a rigid beam, which is characterized in that a geotextile (4) is laid on the surface of a slope (7), a geogrid (5) is laid on the geotextile (4), the outer surface of the geogrid (5) is fixed through a latticed rigid beam (2), and force bearing soil nails (3) which are punched into the slope (7) are used for fixing and bearing force at the cross points of the latticed rigid beam (2), so that the geotextile (4), the geogrid (5), the rigid beam (2) and the force bearing soil nails (3) form an integral force bearing system. The advantages are that: 1. the slope surface does not need a concrete surface layer; 2. the device is suitable for slope surfaces with steep slope-releasing rate; 3. the defects of serious dust emission and large construction noise of an anchor spraying machine in the construction of the existing soil nailing wall supporting system are overcome; 4. the method meets the requirements of the national green construction on assembly type engineering.
Description
Technical Field
The invention discloses a composite soil nailing wall supporting system with a flexible net surface layer and rigid beams, and belongs to the technical field of geotechnical engineering slope supporting/foundation pit supporting.
Background
The soil nailing wall is a supporting structure consisting of a foundation pit side wall soil body or a side slope side wall soil body reinforced by soil nails and a surface layer. In consideration of safety and economy, the soil nailing wall supporting method is widely applied to foundation pit or slope engineering of non-soft soil sites. The existing conventional soil nailing wall supporting system mainly comprises a soil nail and a surface layer. The soil nail is a reinforced body formed by placing a steel bar, a steel pipe or a long and thin rod body material made of high polymer materials into a rock-soil body and injecting cementing materials such as cement in a drilling, driving or injecting mode. The surface layer is a structure which bears the soil pressure of the soil body inside the potential slip crack surface, transmits the soil pressure to the soil nails and limits the lateral displacement generated by the supporting soil body. The surface layer mainly comprises a sprayed concrete surface layer, a cast-in-place concrete surface layer, a precast concrete surface layer, a steel panel, a high polymer material panel and the like. The sprayed concrete surface layer is the most common surface layer type and consists of a steel bar net sheet and a sprayed concrete layer.
The conventional soil nailing wall construction sequence is listed in the current industry standard of the people's republic of China, namely technical regulations on supporting construction foundation pits (JGJ 120-2012):
1) excavating a working face according to the designed slope rate requirement, and manually finishing a side slope;
2) mechanical/manual drilling, installing soil nails and grouting;
3) binding a surface layer reinforcing mesh sheet or laying a prefabricated reinforcing mesh sheet, and welding reinforcing ribs;
4) spraying surface layer concrete;
5) and (5) maintaining.
At present, rigid surface layers such as sprayed concrete, prefabricated steel panels, prefabricated concrete panels and the like are conventionally adopted as surface layers. Has the defects of low construction speed, high construction cost, large dust emission, complex construction process and no environmental protection.
Disclosure of Invention
The invention provides a composite soil nailing wall supporting system of a flexible net surface layer and a rigid beam aiming at the prior art situation, and aims to solve the following problems:
1. the slope surface does not need a concrete surface layer;
2. the device is suitable for slope surfaces with steep slope-releasing rate;
3. the defects of serious dust emission and large construction noise of an anchor spraying machine in the construction of the existing soil nailing wall supporting system are overcome;
4. the method meets the requirements of the national green construction on assembly type engineering.
The purpose of the invention is realized by the following technical scheme:
in the supporting system of the flexible net surface layer and the rigid beam composite soil nailing wall, geotextile 4 is paved on the surface of a slope 7, geogrid 5 is paved on the geotextile 4 to form the flexible net surface layer, the outer surface of the geogrid 5 is fixed through latticed rigid beams 2, and bearing soil nails 3 which are punched into the slope 7 are fixed at the cross points of the latticed rigid beams 2 to bear force, so that the geotextile 4, the geogrid 5, the rigid beams 2 and the bearing soil nails 3 form an integral bearing system.
In one implementation, the geotextile 4 is a combination of one or both of a geomembrane or a geotextile.
In one implementation, geogrid 5 is a bi-directional or a tri-directional geogrid.
In one implementation, a high-strength bolt 8 is installed at the top end of the bearing soil nail 3 and is pressed and connected to the fixed rigid beam 2 through a nut.
In one implementation, the tops of the rigid beams 2, the geotextile 4 and the geogrid 5 are turned outwards to the outside of an upper opening of the slope 7, the turned-out parts are fixed on the tops of the slope 7 by the fixing soil nails 1, and further, the width of the turned-out parts ranges from 1 m to 2 m.
In one implementation, the fixed soil nails 1 and the bearing soil nails 3 are manufactured by a construction mode of hole forming and grouting.
In one embodiment, the slope ratio of the slope 7 is 1: 0.2-1: 0.4.
In one embodiment, the grid-shaped rigid beams 2 have a longitudinal-transverse spacing of 1.0 to 1.5 m.
In the technical scheme of the invention, the fixed soil nails 1 and the force bearing soil nails 3 are fixedly arranged in the holes drilled on the slope 7 soil body by a drilling grouting/driving-in and grouting method, the flexible net surface layer is connected with the rigid beams 2 and the soil nails by the high-strength bolt 8 connecting piece, certain prestress is applied by a torque wrench during connection, the flexible net surface layer is laid on the slope 7 after being tensioned, the lateral soil pressure generated by the slope 7 soil body is transmitted to the force bearing soil nails 3 through the flexible net surface layer and the rigid beams 2, and then transmitted to the stratum beyond a slip crack surface through the force bearing soil nails 3. The restraining effect of the flexible net surface layer and the rigid beam 2 and the reinforcement effect of the bearing soil nails 3 can effectively bear the soil pressure and limit the lateral displacement of the supporting slope, thereby keeping the slope stable.
The grid-shaped rigid beam 2 comprises a plurality of transverse rigid beams and a plurality of longitudinal rigid beams, and the transverse rigid beams and the longitudinal rigid beams are mutually crossed to form a grid-shaped structure.
The existing national industry standard 'construction foundation pit support technical regulation' (JGJ120-2012) does not provide the stress mechanism of the surface layer of the soil nailing wall, so that no calculation formula is given to the surface layer of the soil nailing wall, and the sprayed concrete surface layer of the conventional soil nailing wall is designed according to 'construction requirements'. Some current documents mention that materials such as high-strength fiber nets can be used as surface layers of soil nailing walls, but theoretical support is not provided, the application range is narrow, the soil nailing wall is only suitable for rock and slope-gentle slope-releasing soil layers, and no clear theoretical basis exists in use.
The invention considers through the research of the subject that: the force bearing mechanism of the soil nailing wall is that a comprehensive integral gravity type retaining wall is formed by a surface layer, soil nails and a reinforced soil body, and the soil body behind the wall is prevented from sliding, so that the safety of a foundation pit/side slope is ensured. The following new theory is proposed for the stress of the soil nail wall surface layer: the soil body supported by the soil nailing wall horizontally drives the soil pressure, can be condensed at the end of the soil nailing rod body through the action of the rigid beam and the flexible net surface layer nearby the rigid beam, and then is transmitted to the deep soil body behind the soil nailing wall by the soil nails, and the surface layer only bears the soil pressure of the soil body which slides through the thin-layer wedge-shaped bodies among the rigid beam grids. As shown in fig. 1.
In fig. 2, the thin sliding soil body of the wedge body is taken out as a spacer in the oval range, as shown in fig. 3. Assuming that the wedge-shaped sliding soil body is in a limit balance state, the sliding block bears the self weight G, the sliding surface supporting force N, the sliding surface sliding resistance T and the sliding resistance Ts provided by the soil nail wall surface layer.
As shown in FIG. 4, in the N-S coordinate system, the component G of gravity G
NBalance with the supporting force N; component G of gravity G
TIs balanced with the sum of the slip resistance T and the slip resistance Ts.
G
N＝N (1)
G
T＝T+T
S(2)
Therefore, the temperature of the molten metal is controlled,
T
S＝G
T-T＝G·cosθ-(c·l+G
Ntgφ)＝G·cosθ-(c·l+G·sinθtgφ) (3)
wherein β is the slope angle of the soil nailing wall,
φ
mand (5) average internal friction angle of soil layer.
According to Newton's first law, the stress of the surface layer can be obtained
T'
s＝T
s(4)
In the N-S coordinate system, the pressure T 'born by the face layer can be obtained'
SNAnd pulling force T'
ST
The stress borne by the surface layer can be obtained through the theoretical analysis, because the weight G of the thin-layer wedge-shaped body soil body is small, and the sliding angle ξ is small in value, the stress borne by the surface layer is small, and the thin-layer wedge-shaped body soil body can be completely borne by a flexible net (common symbols which are not noted in the figures and the formulas can be referred to relevant books of soil mechanics and the like).
Drawings
FIG. 1 is a schematic view of active soil pressure agglomeration of soil mass behind a soil nailing wall
FIG. 2 is a schematic view of the soil body pressure of the thin layer wedge-shaped body borne by the flexible net surface layer
FIG. 3 is a force analysis diagram of the separator
FIG. 4 is a surface stress analysis chart
FIG. 5 is a perspective view of the composite soil nailing wall supporting system of the flexible net surface layer and the rigid beam
FIG. 6 is a schematic structural view of the surface of the composite soil nailing wall supporting system of the flexible net surface layer and the rigid beam
FIG. 7 is a schematic structural diagram of a flexible net surface layer in the composite soil nailing wall supporting system of the flexible net surface layer and a rigid beam
In the figure, 1, fixing soil nails; 2. a rigid beam; 3. bearing soil nails; 4. geotextile, 5, geogrid, 6 and grouting body; 7. a slope surface; 8. a high-strength bolt; 9. and (6) drilling.
Detailed Description
The technical scheme of the invention is further detailed in the following by combining the drawings and the embodiment:
referring to fig. 1 to 3, in the present embodiment, in the composite soil nailing wall supporting system of the flexible mesh surface layer and the rigid beam, a drilling hole 9 is formed through manual or mechanical drilling operation, and the fixed soil nail 1 or the force-bearing soil nail 3 is placed in the drilling hole 9 on the slope 7 (the driven soil nail fixes the rod body of the fixed soil nail 1 or the rod body of the force-bearing soil nail 3 on the slope 7 through manual or mechanical equipment). Geotextile 4 and geogrid 5 are laid along the slope 7, and then the rigid beam 2 is placed. The geotextile 4 and the geogrid 5 are connected with the fixed soil nails 1 and the force bearing soil nails 3 through the rigid beams 2 and the high-strength bolts 8 at the ends of the fixed soil nails 1 and the force bearing soil nails 3, and the nuts of the high-strength bolts 8 can be screwed by a torque wrench to apply prestress when the geotextile 4 and the geogrid 5 are connected with the fixed soil nails 1 and the force bearing soil nails 3, so that the geotextile 4 and the geogrid 5 are tightly attached to the slope 7 after being tensioned; when the slope 7 has horizontal lateral displacement, the geotextile 4 and the geogrid 5 are firmly tensioned by the rigid beam 2 and the bearing soil nails 3, and soil pressure generated by the slope 7 is transmitted to the bearing soil nails 3 through the geotextile 4, the geogrid 5, the rigid beam 2 and the high-strength bolts 8 and then transmitted to rock and soil bodies outside the side slope slip crack surface through the bearing soil nails 3. The restriction of the geotextile 4, the geogrid 5, the rigid beam 2 and the high-strength bolt 8 and the tie of the bearing soil nail 3 can effectively limit the displacement of the side slope and keep the stability of the slope 7.
The flexible net surface layer is of a flexible structure, is light in weight, can replace a sprayed concrete surface layer of the conventional technology, and can be conveniently paved on the surface of the slope surface 7 by constructors, so that the construction period of the conventional soil nailing wall support system surface layer concrete and the construction period of arranging the reinforcing mesh on the slope are obviously shortened. In addition, when the flexible net surface layer is subjected to soil pressure generated by the displacement of the slope surface 7, force can be uniformly transmitted to the rigid beam 2 and transmitted to the soil nails through the rigid beam 2, the force transmission mechanism is clear, the section of a rod piece of the soil nails can be effectively designed, and the manufacturing cost is reduced. The geogrid 5 of the flexible net surface layer in the embodiment adopts a three-way geogrid, and has the advantages that: firstly, the structural strength is higher, the rigidity is high, and the block-type wall body is more suitable for field installation in blocks; secondly, its net is the triangle-shaped, compares the bar hole of single-body grid and the quad slit of two-way grid, has better lateral confinement constraint and effectual interlocking function to the ground body, can stabilize domatic 7 ground body better. The inner geomembrane or geotextile can effectively retain water of the slope 7 rock-soil body, so that the natural water content of the slope 7 rock-soil body after excavation cannot be changed violently, and the physical and mechanical parameters of the slope 7 rock-soil body are further influenced.
Because the rigidity of the flexible net surface layer is not enough, the flexible net surface layer is small in restraint after bearing the pressure of the slope 7 rock-soil body, and outward deformation can be large, so that the reinforcing effect is influenced, the flexible net surface layer and the rigid beam 2 composite soil nailing wall form support, the flexible net surface layer is paved on the slope 7 after being tensioned, the tight adhesion is guaranteed, the lateral displacement of the slope 7 rock-soil body can be effectively limited, and the stability of the slope 7 is kept. Compared with the existing soil nailing wall supporting system and the construction method thereof, the flexible net surface layer and rigid beam composite soil nailing wall supporting system and the construction method thereof provided by the invention have obvious advantages. The price of the flexible net surface layer is relatively lower than that of the traditional sprayed concrete surface layer, and the construction cost can be reduced by 30-50 percent; the flexible net surface layer is light in weight and easy to carry, a construction worker can conveniently lay the flexible net surface layer on the surface of the slope 7 in a short time after the slope is formed in the excavation process of the foundation pit, and the adopted flexible net surface layer does not need a maintenance period, so that the supporting efficiency is improved, the construction speed of the slope 7 is accelerated, and the labor intensity of the worker is reduced; meanwhile, the technical scheme of the invention also solves the problems of environmental pollution such as noise, dust emission and the like of sprayed concrete, and improves the working environment of workers; the flexible net surface layer does not need to consume cement, sand and stones, is beneficial to environmental protection and meets the requirements of scientific development and low-carbon economy; the flexible net surface layer and rigid beam composite soil nailing wall supporting system has flexible assembly type characteristics, and after the construction of a building (structure) structure at the bottom of a slope 7 is completed, the nuts 5 are reversely unscrewed, the rigid beam 2 and the flexible net surface layer can be sequentially detached, recovered and transported to the next project for use.
Claims (8)
1. The utility model provides a system is strutted with compound soil nailing wall of rigid beam to flexible net surface course which characterized in that: the system is characterized in that geotextile (4) is laid on the surface of a slope (7), a geogrid (5) is laid on the geotextile (4), the outer surface of the geogrid (5) is fixed through latticed rigid beams (2), and bearing soil nails (3) which are punched into the slope (7) are used for fixing and bearing the force at the cross points of the latticed rigid beams (2), so that the geotextile (4), the geogrid (5), the rigid beams (2) and the bearing soil nails (3) form an integral bearing system.
2. The composite soil nailing wall supporting system of the flexible net surface layer and the rigid beam as claimed in claim 1, wherein: the geotextile (4) is one or the combination of two of geomembrane and geotextile.
3. The composite soil nailing wall supporting system of the flexible net surface layer and the rigid beam as claimed in claim 1, wherein: the geogrid (5) is a bidirectional or three-way geogrid.
4. The composite soil nailing wall supporting system of the flexible net surface layer and the rigid beam as claimed in claim 1, wherein: the top end of the bearing soil nail (3) is provided with a high-strength bolt (8) for fastening the rigid beam (2).
5. The composite soil nailing wall supporting system of the flexible net surface layer and the rigid beam as claimed in claim 1, wherein: the tops of the rigid beams (2), the geotextiles (4) and the geogrids (5) are all turned outwards beyond the upper opening of the slope surface (7), the turned-out parts are fixed at the top of the slope surface (7) through the fixed soil nails (1), and the width range of the turned-out parts is 1-2 m.
6. The composite soil nailing wall supporting system of the flexible net surface layer and the rigid beam as claimed in claim 1 or 5, wherein: the fixed soil nails (1) and the bearing soil nails (3) are manufactured by a construction mode of hole forming and grouting.
7. The composite soil nailing wall supporting system of the flexible net surface layer and the rigid beam as claimed in claim 1, wherein: the slope ratio of the slope surface (7) is 1: 0.2-1: 0.4.
8. The composite soil nailing wall supporting system of the flexible net surface layer and the rigid beam as claimed in claim 1, wherein: the vertical and horizontal intervals of the grid-shaped rigid beams (2) are 1.0-1.5 m.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911146288.2A CN110777823A (en) | 2019-11-19 | 2019-11-19 | Flexible net surface layer and rigid beam composite soil nailing wall supporting system |
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| CN201911146288.2A CN110777823A (en) | 2019-11-19 | 2019-11-19 | Flexible net surface layer and rigid beam composite soil nailing wall supporting system |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111625911A (en) * | 2020-06-04 | 2020-09-04 | 中国科学院长春光学精密机械与物理研究所 | Modeling method for simulating screw connection |
| CN114319378A (en) * | 2021-12-31 | 2022-04-12 | 北京中岩大地科技股份有限公司 | Construction method of flexible face-protecting soil nail wall |
| CN114606959A (en) * | 2022-03-11 | 2022-06-10 | 中国海洋大学 | Flexible net packaged slope early warning support system |
-
2019
- 2019-11-19 CN CN201911146288.2A patent/CN110777823A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111625911A (en) * | 2020-06-04 | 2020-09-04 | 中国科学院长春光学精密机械与物理研究所 | Modeling method for simulating screw connection |
| CN111625911B (en) * | 2020-06-04 | 2023-03-31 | 中国科学院长春光学精密机械与物理研究所 | Modeling method for simulating screw connection |
| CN114319378A (en) * | 2021-12-31 | 2022-04-12 | 北京中岩大地科技股份有限公司 | Construction method of flexible face-protecting soil nail wall |
| CN114606959A (en) * | 2022-03-11 | 2022-06-10 | 中国海洋大学 | Flexible net packaged slope early warning support system |
| CN114606959B (en) * | 2022-03-11 | 2023-07-04 | 中国海洋大学 | Flexible net encapsulation slope early warning support system |
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