CN113463648A - Foundation pit supporting method - Google Patents
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- CN113463648A CN113463648A CN202110656745.3A CN202110656745A CN113463648A CN 113463648 A CN113463648 A CN 113463648A CN 202110656745 A CN202110656745 A CN 202110656745A CN 113463648 A CN113463648 A CN 113463648A
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- 238000000034 method Methods 0.000 title claims abstract description 28
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 67
- 239000010959 steel Substances 0.000 claims abstract description 67
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 46
- 239000004567 concrete Substances 0.000 claims abstract description 30
- 238000010276 construction Methods 0.000 claims abstract description 23
- 239000010410 layer Substances 0.000 claims abstract description 18
- 239000002689 soil Substances 0.000 claims abstract description 17
- 239000004568 cement Substances 0.000 claims abstract description 14
- 238000005507 spraying Methods 0.000 claims abstract description 14
- 238000001914 filtration Methods 0.000 claims abstract description 13
- 239000002344 surface layer Substances 0.000 claims abstract description 13
- 230000003014 reinforcing effect Effects 0.000 claims abstract description 8
- 239000004576 sand Substances 0.000 claims abstract description 8
- 239000000463 material Substances 0.000 claims abstract description 7
- 238000009434 installation Methods 0.000 claims abstract description 5
- 238000009412 basement excavation Methods 0.000 claims description 29
- 238000005553 drilling Methods 0.000 claims description 9
- 239000011150 reinforced concrete Substances 0.000 claims description 8
- 238000007599 discharging Methods 0.000 claims description 5
- 230000009191 jumping Effects 0.000 claims description 4
- 239000004575 stone Substances 0.000 claims description 4
- 238000001514 detection method Methods 0.000 claims description 2
- 238000012544 monitoring process Methods 0.000 description 8
- 238000004873 anchoring Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000011449 brick Substances 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 239000002352 surface water Substances 0.000 description 2
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 1
- 238000009435 building construction Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000011440 grout Substances 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000003466 welding Methods 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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Abstract
The invention discloses a foundation pit supporting method, which comprises the following steps: s1, measuring and paying off; measuring and marking a coordinate point of the foundation pit; s2, building a water retaining wall and a catch basin at the top of the slope; s3, excavating first-stage earthwork; s4, arranging a first-stage slope support; s5, constructing the steel pipe pile, and installing a crown beam; s6, constructing steel sheet piles at four corners of the foundation pit, wherein the elevation of the pile top is flush with the steel pipe pile top; s7, excavating second-stage earthwork; s8, arranging a second-stage slope support; s9, waist beam installation, and concrete spraying by hanging net between piles: the soil between piles is protected by hanging net concrete spraying, and the hanging net concrete spraying adopts the combination of a concrete surface layer and a reinforcing mesh; the drainage holes are arranged in a quincunx manner, and gravel sand is filled at the bottoms of the drainage holes to be used as a water filtering layer; s10, construction of the prestressed anchor cable: the anchor cable is arranged between the steel pipe piles, one end of the anchor cable is anchored into a soil body on the side wall of the foundation pit, the other end of the anchor cable is anchored on the waist beam, secondary pressure grouting is adopted, and P.O 42.5.5 cement paste is adopted as a grouting material of the anchor cable; the invention provides a low-cost, safe and stable foundation pit supporting method.
Description
Technical Field
The invention relates to the technical field of building construction, in particular to a foundation pit supporting method.
Background
The building density in cities is increased along with the advancement of city modernization, the influence of deep foundation pit excavation and support on adjacent buildings, roads and facilities is increasingly prominent, and the foundation pit develops towards a large depth and a large area. The construction of changing old roads into bridges (box culverts) not only meets the current road traffic requirement, but also ensures that the newly-built bridges (box culverts) have enough and safe operation space. The construction methods of slope-laying excavation, deep cement soil stirring of enclosure walls, high-pressure jet grouting piles, channel steel sheet piles, cast-in-situ bored piles, underground continuous walls, soil nail walls, SMW construction methods and the like which are commonly used in China have respective limitations due to the limitation of construction sites, high construction cost, environmental pollution and the like. A single or simple combined construction method cannot effectively solve the above problems, and a method for effectively solving the above problems is urgently needed.
In summary, the prior art also lacks a low-cost, safe and stable method for supporting the foundation pit.
Disclosure of Invention
The invention provides a method for supporting a foundation pit, which is low in cost, safe and stable.
To achieve the purpose, the invention provides the following technical scheme:
a foundation pit supporting method comprises the following steps:
s1, measuring and paying off; measuring and marking a coordinate point of the foundation pit;
s2, building a water retaining wall and a catch basin at the top of the slope;
s3, excavating first-stage earthwork;
s4, arranging a first-stage slope support;
s5, constructing the steel pipe pile, and installing a crown beam;
s6, constructing steel sheet piles at four corners of the foundation pit, wherein the elevation of the pile top is flush with the steel pipe pile top;
s7, excavating second-stage earthwork;
s8, arranging a second-stage slope support;
s9, waist beam installation, and concrete spraying by hanging net between piles: the soil between piles is protected by hanging net concrete spraying, and the hanging net concrete spraying adopts the combination of a concrete surface layer and a reinforcing mesh; the drainage holes are arranged in a quincunx manner, and gravel sand is filled at the bottoms of the drainage holes to be used as a water filtering layer;
s10, construction of the prestressed anchor cable: the anchor cable is arranged between the steel pipe piles, one end of the anchor cable is anchored into a soil body on the side wall of the foundation pit, the other end of the anchor cable is anchored on the waist beam, secondary pressure grouting is adopted, and P.O42.5 cement paste is adopted as a grouting material of the anchor cable.
Preferably, between steps S2 and S3, the method further comprises: and arranging detection points at the periphery of the excavation line.
Preferably, step S3 specifically includes: firstly, a first-stage side slope excavation line is released, and layered excavation is carried out; the height of the side slope is 3-4m, and the slope angle is 40-45 degrees.
Preferably, step S4 specifically includes: a platform is arranged 3-4m below the natural terrace, the slope surface and the slope top are sprayed with a reinforced concrete surface layer within 1.5-2m, the positions of the water drainage holes are arranged according to a quincunx shape, and gravel sand is filled at the bottom of each water drainage hole to serve as a water filtering layer.
Preferably, step S5 specifically includes: and (3) jumping the steel pipe pile at intervals, and drilling a hole at a constant speed by using a spiral drilling machine, wherein the diameter of the hole is 180 mm. The distance between the steel pipe piles is 0.5m, the outer diameter of each steel pipe pile is D160mm, the length of each steel pipe pile is 11m, a crown beam is welded immediately after the steel pipe piles are installed in place by a vibration hammer, the crown beam is made of I18a channel steel, and grouting is conducted in the steel pipe piles until the top of the steel pipe piles. P.O42.5 cement paste is adopted for grouting, the water cement ratio is 0.5-0.6, and the strength of the paste is not lower than M20.
Preferably, step S7 specifically includes: and (3) discharging a second-stage side slope excavation line, wherein the height of the side slope is 3-4m, excavating earthwork in the foundation pit in a layered and sectional manner, the excavation depth of each layer is not more than 1-2m, the sectional excavation length is not more than 30-40m, and the slope coefficient is 1: 1.
Preferably, step S8 specifically includes: the slope surface adopts a sprayed reinforced concrete surface layer, a phi 6@20cmx20cm reinforcing mesh is adopted, the thickness of the sprayed surface is 4-5cm, the strength grade of concrete is C20, a PVC pipe is adopted as a water drainage hole, and the position of the water drainage hole is arranged according to a quincunx shape. The bottom of the drainage hole is filled with gravel as a water filtering layer.
Preferably, the anchor cable of step S10 is selected to match 2S phi 17.8 steel strands, the length is 11m, the aperture of the anchor cable is 150mm, and the drilling downward inclination angle is 15 °.
Preferably, the method also comprises the steps of arranging drainage blind ditches around the bottom of the foundation pit, wherein the top surface of each drainage blind ditch is 40-50cm wide, the bottom of each drainage blind ditch is 20-30cm wide and the height of each drainage blind ditch is 40-50cm, C20 concrete is adopted for pouring, and broken stone aggregate is filled in the drainage blind ditches; the end part of the drainage blind ditch is provided with a sump.
Preferably, the wale is an I18a channel steel.
Preferably, the foundation pit supporting method comprises the following steps:
step one, measurement and paying-off: measuring coordinate points of four corners of the foundation pit by using a total station and marking the coordinate points by using red paint;
and step two, leveling the site, and clearing away garbage, obstacles and the like in the site.
And step three, constructing the water retaining wall and hardening the field, combining the brick water retaining wall and the mortar catch basin on the slope top, discharging surface water, and hardening the exposed part of the slope top by using plain concrete.
And step four, arranging monitoring points, wherein the monitoring points are uniformly arranged at a position 1m outside the excavation boundary line, and each side is not less than 3.
And fifthly, excavating the first-stage soil body, namely firstly putting out a first-stage side slope excavation line with the side slope height of 4m, and excavating in layers with the slope putting coefficient of 1:1 (slope angle of 45 degrees).
Step six, supporting a first-stage side slope, wherein a platform is arranged 4m below a natural terrace, and a reinforced concrete surface layer is sprayed on the slope surface and the top of the slope within 2 m; the positions of the water drainage holes are arranged in a quincunx shape, and gravel sand is filled at the bottom of each water drainage hole to be used as a water filtering layer;
seventhly, constructing the steel pipe piles, installing crown beams, jumping and driving the steel pipe piles at intervals, drilling at uniform speed, immediately welding the crown beams after the steel pipe piles are installed in place, and injecting cement paste into the steel pipe piles;
step eight, construction of Larsen steel sheet piles, namely installing Larsen steel sheet piles at four corners of the foundation pit, and enabling the pile top elevation to be flush with the steel pipe pile top for reinforcement, so that the stability of weak parts of the foundation pit is improved;
step nine, second-stage earthwork excavation, wherein a second-stage side slope excavation line is released, the height of a side slope is 4m, earthwork in a foundation pit is excavated in a layering, layering and segmenting mode, the slope releasing coefficient is 1:1 (slope angle is 45 degrees), and after the second-stage side slope excavation is finished, a waist beam is immediately installed 1 meter below the top of the steel pipe pile;
step ten, supporting the second-stage side slope, wherein the slope surface adopts a sprayed reinforced concrete surface layer, the positions of the drain holes are arranged according to a quincunx shape, and gravel sand is filled at the bottom of the drain holes to serve as a water filtering layer;
step eleven, mounting the waist beam, hanging the concrete in the soil between the piles, spraying the concrete in the soil between the piles by adopting the hanging net, and combining a concrete surface layer and a reinforcing mesh. The water drainage holes are arranged in a quincunx shape, and gravel sand is filled at the bottom of each water drainage hole to be used as a water filtering layer;
and twelfth, constructing the prestressed anchor cables, arranging 1 prestressed anchor cable at a position 1m below the pile top after the steel pipe piles are formed, arranging the anchor cables at a longitudinal interval of 1m between the steel pipe piles, anchoring one end of each anchor cable into a soil body on the side wall of the foundation pit, anchoring one end of each anchor cable on the waist beam, and drilling the hole at an inclination angle of 15 degrees. Secondary pressure grouting is adopted in the prestressed anchor cable construction, and cement paste is adopted as a grouting material;
and step thirteen, drainage blind ditch construction, wherein the drainage blind ditches are arranged on the periphery of the bottom of the foundation pit, the drainage blind ditches are poured by C20 concrete, broken stone aggregate is filled in the drainage blind ditches, a water collecting pit is arranged at the end part of each drainage blind ditch so as to be beneficial to pumping water down, and the drainage blind ditches are discharged into nearby drainage ditches after being processed to be qualified.
Compared with the prior art, the invention has the beneficial effects and remarkable progresses that: the foundation pit supporting method provided by the invention reinforces the weak part of the foundation pit through layered and partitioned construction, and improves the stability of the foundation pit. On the premise of ensuring safety and quality, the construction process is optimized, the construction site is reasonably utilized, the manufacturing cost is reduced, and the environment is protected. The foundation pit supporting method provided by the invention can ensure the advantages of construction methods such as slope excavation, steel sheet pile and pile arrangement under the condition that the old road is changed into a bridge (box culvert) and the excavation depth of the foundation pit is less than 9 m.
Drawings
To more clearly illustrate the technical solution of the present invention, the drawings required for the embodiment of the present invention will be briefly described below.
It should be apparent that the drawings in the following description are only drawings of some embodiments of the invention, and that other drawings can be obtained by those skilled in the art without inventive exercise, and the other drawings also belong to the drawings required by the embodiments of the invention.
Fig. 1 is a flowchart of a method of supporting a foundation pit according to an embodiment of the present invention;
FIG. 2 is a plan view of a foundation pit support according to an embodiment of the present invention;
FIG. 3 is a cross-sectional view of a foundation pit A-A according to an embodiment of the present invention;
FIG. 4 is a cross-sectional view of a foundation pit B-B according to an embodiment of the present invention;
in the figure, 1, a monitoring point, 2, a first-stage side slope, 3, a platform, 4, a second-stage side slope, 5, a steel pipe pile, 6, a drainage blind ditch, 7, a Larsen steel plate pile, 8, a water retaining wall, 9, a road, 10, a catch basin, 11, a prestressed anchor cable, 12, a crown beam, 13 and a waist beam.
Detailed Description
In order to make the objects, technical solutions, advantageous effects and significant progress of the embodiments of the present invention clearer and more complete, the technical solutions in the embodiments of the present invention will be described below with reference to the drawings provided in the embodiments of the present invention.
It is to be understood that all of the described embodiments are merely some, and not all, embodiments of the invention; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It is to be understood that:
in the present invention, unless otherwise specifically stated or limited, the terms "mounted," "connected," "fixed," and the like are to be understood broadly, and for example, may be fixedly connected, detachably connected, movably connected, or integrated; either directly or indirectly through intervening media, intangible signal, or even optical, communication between two elements, or an interaction between two elements, unless expressly limited otherwise.
The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
It should be further noted that the following embodiments may be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments.
The technical means of the present invention will be described in detail below with specific examples.
As shown in fig. 1, there is shown a method of retaining and protecting a foundation pit, comprising the steps of:
firstly, measuring and paying off;
step two, leveling the field;
step three, constructing the water retaining wall and hardening the slope top;
fourthly, arranging monitoring points;
step five, excavating the first-stage earthwork;
step six, first-stage slope support;
constructing the steel pipe pile and installing the crown beam;
eighthly, constructing steel sheet piles at four corners of the foundation pit;
step nine, excavating a second-level soil body;
step ten, simultaneously carrying out second-stage slope support, waist beam installation and inter-pile soil hanging net concrete spraying;
eleventh, constructing a prestressed anchor cable;
twelfth, drainage blind ditch construction;
and thirteen, subsequent foundation construction.
As shown in fig. 2-4, a schematic structural diagram of a foundation pit support is shown, which includes a monitoring point 1, a first-stage side slope 2, a platform 3, a second-stage side slope 4, a steel pipe pile 5, a drainage blind ditch 6, a larsen steel sheet pile 7, a retaining wall 8, a road 9, a catch basin 10, a prestressed anchor cable 11, a crown beam 12 and a wale 13. The concrete steps of the foundation pit support comprise:
A. and (3) measurement and paying-off: and firstly, measuring coordinate points at four corners of the foundation pit by using a total station and marking the coordinate points by using red paint.
B. Leveling the field: clearing away garbage, obstacles and the like in the field.
C. Water retaining wall construction and slope top hardening: the slope top is formed by combining a brick retaining wall 8 of 20cm by 30cm and a grout intercepting ditch 10 of 50cm by 50cm, surface water is discharged, and exposed parts of the slope top are hardened by plain concrete of 2 cm.
D. Arranging monitoring points: monitoring points 1 are uniformly arranged at a position 1m outside the excavation boundary. The horizontal distance of the monitoring points 1 is not more than 20m, and each side is not less than 3.
E. Excavating the earth at the first stage: firstly, a first-stage side slope 2 excavation line is released, the height of the side slope is 4m, foundation pit earthwork is excavated in a layered and sectional mode, the excavation depth of each layer is not more than 2m, the sectional excavation length is not more than 40m, and the slope releasing coefficient is 1:1 (slope angle is 45 degrees).
F. First-stage slope support: a platform 3 with the width of 1.5m is arranged 4.0m below the natural terrace, and the reinforced concrete surface layer is sprayed on the slope surface and the top of the slope within the range of 2 m. The steel bar net is set by adopting phi 6@20cmx20cm, the thickness of a spraying surface is 5cm, and the strength grade of concrete is C20. The drainage hole adopts a PVC pipe, the outer diameter D75mm and the length 1 m. The positions of the water discharge holes are arranged in a quincunx shape with the longitudinal direction of 2m and the transverse direction of 2 m. The bottom of the drainage hole is filled with gravel as a water filtering layer.
G. Steel pipe pile construction, crown beam installation: and (3) jumping the steel pipe pile 5 at intervals, and drilling a hole with a spiral drilling machine at a constant speed, wherein the diameter of the hole is 180 mm. The distance between the steel pipe piles 5 is 0.5m, the outer diameter of each steel pipe pile is D160mm, the length of each steel pipe pile is 11m, after the steel pipe piles 5 are installed in place by a vibration hammer, a crown beam 12 is welded immediately, the crown beam 12 adopts I18a channel steel, and grouting is conducted in the steel pipe piles 5 until the top of the steel pipe piles. P.O42.5 cement paste is adopted for grouting, the water cement ratio is 0.5-0.6, and the strength of the paste is not lower than M20.
H. Constructing steel sheet piles at four corners of the foundation pit: and inserting and driving 5m long Larsen steel sheet piles 7 with the height of 9m into the mechanical arms modified by the excavator on the four corners of the foundation pit, and reinforcing the pile top elevation and the steel pipe pile top to improve the stability of the weak part of the foundation pit.
I. And (3) second-stage earthwork excavation: and (3) discharging a second-level side slope 4 excavation line, wherein the height of the side slope is 4m, excavating earthwork in the foundation pit in a layered and sectional manner, the excavation depth of each layer is not more than 2m, the sectional excavation length is not more than 40m, and the slope coefficient is 1:1 (slope angle is 45 degrees). And after the second-stage side slope 4 is excavated, immediately installing a wale 13 1m below the top of the steel pipe pile 5, wherein the wale 13 adopts I18a channel steel.
J. And (3) second-stage slope support: the slope surface adopts a sprayed reinforced concrete surface layer, a phi 6@20cmx20cm reinforcing mesh is adopted, the thickness of the sprayed surface is 5cm, and the strength grade of concrete is C20. The drain hole adopts a PVC pipe, the outer diameter is 75mm, and the length is 1 m. The positions of the water discharge holes are arranged in a quincunx shape with the longitudinal direction of 2m and the transverse direction of 2 m. The bottom of the drainage hole is filled with gravel as a water filtering layer.
K. Installing waist beams, and spraying concrete by using an inter-pile soil hanging net: the soil between piles is protected by hanging net and spraying concrete, and is combined by reinforcing steel bar nets with the thickness of 5cmC20 concrete surface layer + phi 6@20cmx20 cm. The drain hole adopts a PVC pipe, the outer diameter is 75mm, and the length is 1 m. The positions of the water discharge holes are arranged in a quincunx shape with the longitudinal direction of 2m and the transverse direction of 2 m. The bottom of the drainage hole is filled with gravel as a water filtering layer.
L, prestressed anchor cable construction: after the steel pipe piles 5 are formed into holes, 1 prestressed anchor cable 11 is arranged at a position 1m below the pile tops, the anchor cables are longitudinally spaced by 1m and arranged between the steel pipe piles, one end of each anchor cable is anchored into a soil body on the side wall of a foundation pit, the other end of each anchor cable is anchored on a waist beam 13, and the anchoring length is 11 m. The aperture of the anchor cable is 150mm, the downward inclination angle of the drill hole is 15 degrees, and 2s phi 17.8 steel strands are selected and matched. The construction of the prestressed anchor cable 11 adopts secondary pressure grouting, the grouting material of the anchor cable adopts P.O42.5 cement paste, the water cement ratio is 0.5-0.6, and the strength of the paste is not lower than M20.
M, drainage blind ditch construction: the periphery of the bottom of the foundation pit is provided with a drainage blind ditch 6, the top surface of the drainage blind ditch is 50cm wide, the bottom of the drainage blind ditch is 30cm wide and the height of the drainage blind ditch is 50cm, C20 concrete with the thickness of 30cm is adopted for pouring, and broken stone aggregate is filled in the drainage blind ditch. The end part of the drainage blind ditch 6 is provided with a water collecting pit which is beneficial to pumping water downwards and discharging the water into a nearby drainage ditch after the water is qualified after treatment.
During the description of the above description:
the description of the terms "this embodiment," "an embodiment of the invention," "as shown at … …," "further improved technical solution," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention; in this specification, the schematic representations of the terms used above are not necessarily for the same embodiment or example, and the particular features, structures, materials, or characteristics described, etc., may be combined or brought together in any suitable manner in any one or more embodiments or examples; furthermore, those of ordinary skill in the art may combine or combine features of different embodiments or examples and features of different embodiments or examples described in this specification without undue conflict.
Finally, it should be noted that:
the above embodiments are only used for illustrating the technical solution of the present invention, and not for limiting the same;
although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof without departing from the scope of the embodiments of the present invention.
Claims (10)
1. A foundation pit supporting method is characterized by comprising the following steps:
s1, measuring and paying off; measuring and marking a coordinate point of the foundation pit;
s2, building a water retaining wall and a catch basin at the top of the slope;
s3, excavating first-stage earthwork;
s4, arranging a first-stage slope support;
s5, constructing the steel pipe pile, and installing a crown beam;
s6, constructing steel sheet piles at four corners of the foundation pit, wherein the elevation of the pile top is flush with the steel pipe pile top;
s7, excavating second-stage earthwork;
s8, arranging a second-stage slope support;
s9, waist beam installation, and concrete spraying by hanging net between piles: the soil between piles is protected by hanging net concrete spraying, and the hanging net concrete spraying adopts the combination of a concrete surface layer and a reinforcing mesh; the drainage holes are arranged in a quincunx manner, and gravel sand is filled at the bottoms of the drainage holes to be used as a water filtering layer;
s10, construction of the prestressed anchor cable: the anchor cable is arranged between the steel pipe piles, one end of the anchor cable is anchored into a soil body on the side wall of the foundation pit, the other end of the anchor cable is anchored on the waist beam, secondary pressure grouting is adopted, and P.O42.5 cement paste is adopted as a grouting material of the anchor cable.
2. A method of retaining and protecting a foundation pit as claimed in claim 1, further comprising between steps S2 and S3: and arranging detection points at the periphery of the excavation line.
3. A method for foundation pit support as claimed in claim 1, wherein step S3 specifically includes: firstly, a first-stage side slope excavation line is released, and layered excavation is carried out; the height of the side slope is 3-4m, and the slope angle is 40-45 degrees.
4. A method for foundation pit support as claimed in claim 1, wherein step S4 specifically includes: a platform is arranged 3-4m below the natural terrace, the slope surface and the slope top are sprayed with a reinforced concrete surface layer within 1.5-2m, the positions of the water drainage holes are arranged according to a quincunx shape, and gravel sand is filled at the bottom of each water drainage hole to serve as a water filtering layer.
5. A method for foundation pit support as claimed in claim 1, wherein step S5 specifically includes: and (3) jumping the steel pipe pile at intervals, and drilling a hole at a constant speed by using a spiral drilling machine, wherein the diameter of the hole is 180 mm. The distance between the steel pipe piles is 0.5m, the outer diameter of each steel pipe pile is D160mm, the length of each steel pipe pile is 11m, a crown beam is welded immediately after the steel pipe piles are installed in place by a vibration hammer, the crown beam is made of I18a channel steel, and grouting is conducted in the steel pipe piles until the top of the steel pipe piles. P.O42.5 cement paste is adopted for grouting, the water cement ratio is 0.5-0.6, and the strength of the paste is not lower than M20.
6. A method for foundation pit support as claimed in claim 1, wherein step S7 specifically includes: and (3) discharging a second-stage side slope excavation line, wherein the height of the side slope is 3-4m, excavating earthwork in the foundation pit in a layered and sectional manner, the excavation depth of each layer is not more than 1-2m, the sectional excavation length is not more than 30-40m, and the slope coefficient is 1: 1.
7. A method for foundation pit support as claimed in claim 1, wherein step S8 specifically includes: the slope surface adopts a sprayed reinforced concrete surface layer, a phi 6@20cmx20cm reinforcing mesh is adopted, the thickness of the sprayed surface is 4-5cm, the strength grade of concrete is C20, a PVC pipe is adopted as a water drainage hole, and the position of the water drainage hole is arranged according to a quincunx shape. The bottom of the drainage hole is filled with gravel as a water filtering layer.
8. A method of supporting a foundation pit as claimed in claim 1, wherein the anchor cables of step S10 are provided with strands of 2S Φ 17.8 steel, a length of 11m, a cable bore diameter of 150mm and a borehole inclination of 15 °.
9. A foundation pit supporting method as claimed in claim 1, further comprising arranging drainage blind ditches around the bottom of the foundation pit, wherein the drainage blind ditches are 40-50cm wide in top surface, 20-30cm wide in bottom and 40-50cm high, cast with C20 concrete, and filled with crushed stone aggregate; the end part of the drainage blind ditch is provided with a sump.
10. A method of retaining and protecting a foundation pit as claimed in claim 1, wherein the wale is I18a channel steel.
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| CN115059096A (en) * | 2022-03-30 | 2022-09-16 | 上海二十冶建设有限公司 | Construction method of shale geology adjacent to rotational flow pool of existing factory building |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115059096A (en) * | 2022-03-30 | 2022-09-16 | 上海二十冶建设有限公司 | Construction method of shale geology adjacent to rotational flow pool of existing factory building |
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