CN112281836A - Self-drilling anchor rod construction method for pore submersible deep foundation pit - Google Patents

Self-drilling anchor rod construction method for pore submersible deep foundation pit Download PDF

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Publication number
CN112281836A
CN112281836A CN202011111092.2A CN202011111092A CN112281836A CN 112281836 A CN112281836 A CN 112281836A CN 202011111092 A CN202011111092 A CN 202011111092A CN 112281836 A CN112281836 A CN 112281836A
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anchor
construction
anchor rod
drilling
grouting
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Inventor
王胜涛
耿进山
欧阳广昊
侯庆敏
赵若天
张思涛
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China Construction Eighth Engineering Division Co Ltd
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China Construction Eighth Engineering Division Co Ltd
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Priority to CN202011111092.2A priority Critical patent/CN112281836A/en
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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
    • E02D5/74—Means for anchoring structural elements or bulkheads
    • E02D5/76—Anchorings for bulkheads or sections thereof in as much as specially adapted therefor
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D15/00—Handling building or like materials for hydraulic engineering or foundations
    • E02D15/02—Handling of bulk concrete specially for foundation or hydraulic engineering purposes
    • E02D15/04—Placing concrete in mould-pipes, pile tubes, bore-holes or narrow shafts
    • 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
    • E02D33/00—Testing foundations or foundation structures
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2250/00—Production methods
    • E02D2250/003—Injection of material
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2300/00—Materials
    • E02D2300/0004—Synthetics
    • E02D2300/0018—Cement used as binder
    • E02D2300/0023—Slurry

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  • Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Paleontology (AREA)
  • Civil Engineering (AREA)
  • Piles And Underground Anchors (AREA)

Abstract

The invention provides a self-drilling anchor rod construction method for a pore diving deep foundation pit, which belongs to the technical field of self-drilling anchor rod construction, and is used for the construction of a self-drilling anchor rod for geology with larger water content and large void degree, thereby effectively preventing hole collapse, ensuring the bonding strength of cement paste and a pore wall rock mass, actively providing anti-sliding force, effectively controlling the displacement of the rock mass, and generating a sub-stress zone in the anchoring range of an anchor cable, thereby fundamentally improving the mechanical property of the rock mass, various special drill bits with special performance matched with the self-drilling anchor rod can be suitable for various stratums, a high-strength connecting sleeve processed by adopting a mechanical cutting process has the characteristic of lengthening while drilling, so that the self-drilling anchor rod can construct a longer anchor rod in a narrow construction space, the grouting is convenient and compact, the anchoring strength is increased, and compared with the construction of a common anchor rod, the construction cost can be greatly reduced, meanwhile, the energy is saved, the emission is reduced, and the environment-friendly construction is facilitated.

Description

Self-drilling anchor rod construction method for pore submersible deep foundation pit
Technical Field
The invention belongs to the technical field of self-drilling anchor rod construction, and particularly relates to a self-drilling anchor rod construction method for a pore submersible deep foundation pit.
Background
The self-drilling anchor rod construction method for the pore submersible deep foundation pit is a construction method that a self-drilling anchor rod is adopted to drill and grout in the pore submersible deep foundation pit, the grout is grouted and solidified through a hollow hole, part of the grout penetrates into surrounding rock cracks under pressure, the solidified surrounding rock forms a whole, and rock bodies within a certain thickness range around the whole form a bearing ring. Wherein, the outer end of the anchor cable is fixed on the concrete pile body, and the other end is anchored in the stable rock mass. The prestress of the anchor cable enables the unstable soil body to be in a higher confining pressure state, the structural surface is in a compression state, the integrity of the structure is improved, the anchoring force of the anchor cable and the pulling resistance force of the anchor rod change the stress state and the sliding stability condition on the sliding surface, and the stability of the surrounding rock is improved.
The quality of the construction of the anchor rod of the pore diving deep foundation pit directly relates to the safety of the building. However, the conventional method is to drill and grout the common anchor rod. This often requires a long time and is costly to survey, and because of the limited number of spots, it is impossible to drill everywhere, so it is impossible to do a good job.
Disclosure of Invention
The embodiment of the invention provides a self-drilling anchor rod construction method for a pore submersible deep foundation pit, and aims to solve the problem that the conventional method for drilling and grouting by using a common anchor rod is adopted. This often requires a long time and is expensive to survey, and because of the limited number of spots, it is impossible to drill everywhere, so that it is impossible to construct a good job.
In view of the above problems, the technical solution proposed by the present invention is:
the invention provides a self-drilling anchor rod construction method for a pore submersible deep foundation pit, which is characterized by comprising the following steps of:
s1, preparing before construction, building a construction platform in a construction area, positioning and lofting the area to be drilled by constructors, and cleaning rock surface floating soil, loose rocks, vegetation and material approach of a construction site;
s1a, setting up a construction platform, and setting up the construction platform in the construction area according to the construction area marked by the survey in advance;
s1b, positioning and lofting, determining hole positions according to drawing design requirements, and determining a water slurry construction mix proportion according to the acquired data;
s1c, leveling a field, realizing field tee joint according to the requirements of a construction field, cleaning the rock surface of an anchor rod hole opening to ensure that the rock surface is vertical to the required drilling direction, and simultaneously drilling matched equipment, grouting equipment and tensioning equipment enter the field;
s2, drilling construction, after each matched facility enters the field, putting drill rods needed by the drilling machine in order according to the design length of the anchor cable, and enabling the drilled hole depths of the drill rods to be just in place, wherein the lengths of the drill rods have errors of +/-5 mm, the actual drilling depth is required to exceed the design hole depth by 0.5m, stratum changes of each hole are met in the drilling process, and field records are made under some special conditions;
s3, manufacturing and installing anchor cables, after drilling, manufacturing the anchor cables on a site which is cleaned in advance according to the blanking length, and installing the anchor cables in anchor cable holes which are drilled in advance;
s3a, anchor cable manufacturing, wherein the length of an anchor rod is determined according to drawing design requirements and soil layer conditions of a construction site, anchor cable manufacturing is carried out on a site cleaned in advance according to blanking length, and meanwhile, the length error of each stranded wire is controlled to be 10 cm;
s3b, installing the anchor cable, checking whether the serial number of the anchor cable is consistent with the serial number of the anchor cable before installing the anchor cable in the anchor cable hole, manually lifting the anchor cable to a working surface after the serial number of the anchor cable is confirmed to be correct, manually penetrating the anchor cable into the anchor hole smoothly, stopping penetrating the anchor cable when the exposed part meets the working length, and performing grouting work after the installation work of the anchor cable is finished;
s4, grouting construction, wherein the grouting material is pure cement slurry, cement is ordinary silicate 425, the water cement ratio is 0.5, 10% of UEA-Z type composite expanding agent and 0.6% of high-efficiency early-strength water reducing agent are additionally added, the slurry strength is not less than 40MPa, a grouting pipe is slowly drawn while grouting is carried out, the grouting pipe orifice is ensured to be positioned at the slurry level, the slurry is ensured to be dense and saturated, the designed slurry strength is reached, grouting can be stopped when clear slurry overflows from an orifice, relevant records are made in the grouting process, and test blocks are made;
s5, carrying out an anchor rod pullout resistance test, carrying out the pullout resistance test at an actual site after the strength of the anchor hole grouting body meets the design requirement, wherein in the test process, the used tension meter and the exposed part of the anchor rod are kept parallel, and meanwhile, the tension is carried out by keeping constant and slow tension;
s6, sealing the anchor, after backfilling is filled in place according to the procedures, tensioning and locking all anchor cables on the pile, monitoring the pile position when tensioning is needed each time, cutting off redundant steel strands by using a lifting sand turbine after prestress tensioning is completed, keeping the length of the steel strands to be 20cm, finally installing a protective cover on the anchor rod, filling grease for sealing the anchor, and keeping the pile surface neat and attractive after sealing the anchor;
s7, monitoring axial force, selecting representative anchor holes before applying the axial force of the anchor cable, installing special sensor elements at the selected anchor holes, installing anchors, measuring the change condition of the axial force of the anchor cable at different periods through applying and observing prestress, and accordingly carrying out relevant processing, wherein the reading of the axial force is observed corresponding to the soil filling condition and the pile body displacement condition.
As a preferred technical solution of the present invention, the calculation formula of the anchor rod of step S3a for the layered rock is:
L1＝C1+H+C2；
in the formula: l is1-length of layered rock bolt (m);
C1the depth range of the anchor rod inserted into the hard rock is 250 mm-300 mm;
h, directly anchoring the wall rock to the thickness;
c2 — anchor bar exposed length.
As a preferred technical solution of the present invention, the calculation formula of the anchor rod of step S3a for the non-layered rock is:
Figure BDA0002728621510000041
in the formula: l is2-length of anchor rod (m) in non-stratified rock;
b-tunnel width (m).
In a preferred embodiment of the present invention, the pressure range of the grouting in step S4 is 0.5 Mpa-0.8 Mpa.
As a preferred technical solution of the present invention, the calculation formula of the amount of slurry in step S4 is:
Q＝λπRLnβ；
in the formula: q-pressing amount of Single-hole slurry (m)3)；
Lambda is a loss coefficient, and 1.1-1.5 is taken;
r-slurry diffusion radius (m);
l is the length (m) of the grouting section;
n-volume fracture rate, taking 1-10% and broken zone taking 30-40%;
and taking 0.3-0.9 as the effective filling coefficient of the beta-slurry in the fracture.
Compared with the prior art, the invention has the beneficial effects that:
(1) for geology with large water content and large void degree, self-drilling anchor rod construction is adopted, so that hole collapse can be effectively prevented, and the bonding strength of cement paste and a hole wall rock body is ensured.
(2) The anchor cable can actively provide anti-sliding force, effectively control the displacement of the rock mass and generate a sub-stress zone in the anchoring range of the anchor cable, thereby fundamentally improving the mechanical property of the rock mass.
(3) The special drill bits with special performance matched with the self-drilling anchor rod are suitable for various stratums.
(4) The self-drilling anchor rod has the characteristic of lengthening while drilling by adopting the high-strength connecting sleeve processed by a mechanical cutting process, so that the self-drilling anchor rod can be used for constructing a longer anchor rod in a narrow construction space.
(5) The grouting is convenient and compact, and the anchoring strength is increased.
(6) Compared with the construction of a common anchor rod, the construction cost can be greatly reduced, energy is saved, emission is reduced, and environment-friendly construction is facilitated.
(7) Construction safety eliminates equipment moving and carrying, and reduces labor intensity of operators.
The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.
Drawings
Fig. 1 is a flow chart of a self-drilling anchor rod construction method for a pore submersible deep foundation pit disclosed by the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the equipment or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
Examples
Referring to the attached figure 1, the invention provides a technical scheme: a self-drilling anchor rod construction method for a pore submersible deep foundation pit comprises the following steps:
s1, preparing before construction, building a construction platform in a construction area, positioning and lofting the area to be drilled by constructors, and cleaning rock surface floating soil, loose rocks, vegetation and material approach of a construction site;
in this embodiment, the steps are:
s1a, setting up a construction platform, and setting up the construction platform in the construction area according to the previously surveyed and marked construction area;
s1b, positioning and lofting, determining hole positions according to drawing design requirements, and determining a water slurry construction mix proportion according to the acquired data;
s1c, leveling a field, realizing field tee joint according to the requirements of a construction field, cleaning the rock surface of an anchor rod hole opening to ensure that the rock surface is vertical to the required drilling direction, and simultaneously drilling matched equipment, grouting equipment and tensioning equipment enter the field;
specifically, the construction site tee joint is an electric joint, a water joint and a road joint; if the rock surface is not perpendicular to the required drilling direction, the special backing plate can be used for adjustment when the anchor rod is installed, so that the supporting plate is closely attached to the rock surface.
S2, drilling construction, after each matched facility enters the field, putting drill rods needed by the drilling machine in order according to the design length of the anchor cable, and enabling the drilled hole depths of the drill rods to be just in place, wherein the lengths of the drill rods have errors of +/-5 mm, the actual drilling depth is required to exceed the design hole depth by 0.5m, stratum changes of each hole are met in the drilling process, and field records are made under some special conditions;
specifically, drilling is a key process for controlling the construction period in the self-drilling anchor cable construction of the deep foundation pit, in order to improve the drilling efficiency and ensure the drilling quality, an MG-20 percussion drill is preferentially adopted in the construction process, and a drill bit is preferentially adopted
Figure BDA0002728621510000081
The drill rods of the quincunx alloy steel drill bit are required to be of uniform specification; meanwhile, in order to prevent the deterioration of the engineering geological conditions of the slope rock mass and reduce the cohesiveness of the hole wall, water injection drilling is strictly forbidden; in the drilling process, if stratum is loose and broken, casing drilling technology is applied to ensure that the drilled hole is complete and does not collapse, if the drilled hole is collapsed or underground water is abundant, the drilling is stopped immediately, wall-fixing grouting treatment is carried out, the grouting pressure range is 0.2-0.4 Mpa, and after cement slurry is solidified, hole sweeping drilling is carried out again; and under the condition of complicated geology, drilling holes by adopting a sleeve following method with the same anchor rod diameter, wherein pressure water flows to the bottom of the hole from a drill pipe during drilling, under a certain water head pressure, water flow carries drilled soil scraps to be discharged out of a drilled soil scrap discharge hole, water is continuously supplied and flushed during drilling, the drill pipe is lengthened and temporarily stopped, the water level of a hole opening is kept all the time, if the situation that the water cannot be pressed into the hole, the pipe is blocked, the drill pipe is pulled out, a clay plug is taken out, the hole is continuously drilled, and the drill rig drills to a specified depthThe rotation is continued and the water is pressed to wash away the soil chips remained in the holes until the effluent water is not turbid.
S3, manufacturing and installing anchor cables, after drilling, manufacturing the anchor cables on a site which is cleaned in advance according to the blanking length, and installing the anchor cables in anchor cable holes which are drilled in advance;
in this embodiment, the steps are:
s3a, anchor cable manufacturing, wherein the length of the anchor rod is determined according to the design requirement of a drawing and the soil layer condition of a construction site, the anchor cable manufacturing is carried out on a site which is cleaned in advance according to the blanking length, and the length error of each stranded wire is controlled to be 10 cm;
s3b, installing the anchor cable, checking whether the serial number of the anchor cable is consistent with the serial number of the anchor cable before installing the anchor cable in the anchor cable hole, manually lifting the anchor cable to a working surface after the serial number of the anchor cable is confirmed to be correct, manually penetrating the anchor cable into the anchor hole smoothly, stopping penetrating the anchor cable when the exposed part meets the working length, and performing grouting work after the installation work of the anchor cable is finished;
s4, grouting construction, wherein the grouting material is pure cement slurry, cement is ordinary silicate 425, the water cement ratio is 0.5, 10% of UEA-Z type composite expanding agent and 0.6% of high-efficiency early-strength water reducing agent are additionally added, the slurry strength is not less than 40MPa, a grouting pipe is slowly drawn while grouting is carried out, the grouting pipe orifice is ensured to be positioned at the slurry level, the slurry is ensured to be dense and saturated, the designed slurry strength is reached, grouting can be stopped when clear slurry overflows from an orifice, relevant records are made in the grouting process, and test blocks are made;
specifically, the grouting is performed by a grouting pump, the stirring is performed by a mortar stirrer, the slurry is uniformly stirred, is used along with the stirring and is used up before initial setting, and impurities such as stones are prevented from being mixed into the slurry strictly; in the processes of upward inclination and horizontal anchor cable hole grouting, when the exhaust pipe does not exhaust any more and dilute cement paste is extruded from the exhaust pipe, the grouting is full; and for grouting of the declined anchor cable, a mortar position indicator is adopted to control a grouting position, a grouting machine is adopted for grouting of the anchor cable hole, and the grouting pressure is kept in the range of 0.5-0.8 MPa.
It should be noted that the specific model specifications of the grouting pump, the mortar mixer and the grouting machine need to be determined according to the actual specification of the device, and the specific model selection calculation method adopts the prior art, so detailed description is omitted.
S5, carrying out an anchor rod pullout resistance test, carrying out the pullout resistance test at an actual site after the strength of the anchor hole grouting body meets the design requirement, wherein in the test process, the used tension meter and the exposed part of the anchor rod are kept parallel, and meanwhile, the tension is carried out by keeping constant and slow tension;
s6, sealing the anchor, after backfilling is filled in place according to the procedures, tensioning and locking all anchor cables on the pile, monitoring the pile position when tensioning is needed each time, cutting off redundant steel strands by using a lifting sand turbine after prestress tensioning is completed, keeping the length of the steel strands to be 20cm, finally installing a protective cover on the anchor rod, filling grease for sealing the anchor, and keeping the pile surface neat and attractive after sealing the anchor;
s7, monitoring axial force, selecting representative anchor holes before applying the axial force of the anchor cable, installing special sensor elements at the selected anchor holes, installing anchors, measuring the change condition of the axial force of the anchor cable at different periods through applying and observing prestress, and accordingly carrying out relevant processing, wherein the reading of the axial force is observed corresponding to the soil filling condition and the pile body displacement condition.
In the embodiment of the present invention, the calculation formula of the step S3a anchor rod for the layered rock is as follows:
L1＝C1+H+C2；
in the formula: l is1-length of layered rock bolt (m);
C1the depth range of the anchor rod inserted into the hard rock is 250 mm-300 mm;
h, directly anchoring the wall rock to the thickness;
C2-anchor rod exposed length.
In the embodiment of the present invention, the calculation formula of the step S3a anchor rod for non-laminar rock is:
Figure BDA0002728621510000101
in the formula: l is2-length of anchor rod (m) in non-stratified rock;
b-tunnel width (m).
In the embodiment of the present invention, the pressure range of the grouting in the step S4 is 0.5-0.8 Mpa.
In the embodiment of the present invention, the calculation formula of the amount of slurry in step S4 is:
Q＝λπRLnβ；
in the formula: q-pressing amount of Single-hole slurry (m)3)；
Lambda is a loss coefficient, and 1.1-1.5 is taken;
r-slurry diffusion radius (m);
l is the length (m) of the grouting section;
n-volume fracture rate, taking 1-10% and broken zone taking 30-40%;
and taking 0.3-0.9 as the effective filling coefficient of the beta-slurry in the fracture.
The invention provides a self-drilling anchor rod construction method of a pore diving deep foundation pit, which adopts the self-drilling anchor rod construction for geology with larger water content and large void degree, can effectively prevent hole collapse, ensure the bonding strength of cement paste and a hole wall rock mass, actively provide anti-slip force, effectively control the displacement of the rock mass and generate a sub-stress zone in the anchoring range of an anchor cable, thereby fundamentally improving the mechanical property of the rock mass, various special drill bits with special performance matched with the self-drilling anchor rod can be suitable for various stratums, and a high-strength connecting sleeve processed by adopting a mechanical cutting process is adopted, the self-drilling anchor rod has the characteristic of lengthening the drilling edge, so that the self-drilling anchor rod can construct a longer anchor rod in a narrow construction space, the grouting is convenient and compact, the anchoring strength is increased, compared with the common anchor rod construction, the construction cost can be greatly reduced, and the energy is saved and the emission is reduced, is beneficial to environment-friendly construction.
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 (5)

1. A self-drilling anchor rod construction method for a pore submersible deep foundation pit is characterized by comprising the following steps:
s1, preparing before construction, building a construction platform in a construction area, positioning and lofting the area to be drilled by constructors, and cleaning rock surface floating soil, loose rocks, vegetation and material approach of a construction site;
s1a, setting up a construction platform, and setting up the construction platform in the construction area according to the construction area marked by the survey in advance;
s1b, positioning and lofting, determining hole positions according to drawing design requirements, and determining a water slurry construction mix proportion according to the acquired data;
s1c, leveling a field, realizing field tee joint according to the requirements of a construction field, cleaning the rock surface of an anchor rod hole opening to ensure that the rock surface is vertical to the required drilling direction, and simultaneously drilling matched equipment, grouting equipment and tensioning equipment enter the field;
s2, drilling construction, after each matched facility enters the field, putting drill rods needed by the drilling machine in order according to the design length of the anchor cable, and enabling the drilled hole depths of the drill rods to be just in place, wherein the lengths of the drill rods have errors of +/-5 mm, the actual drilling depth is required to exceed the design hole depth by 0.5m, stratum changes of each hole are met in the drilling process, and field records are made under some special conditions;
s3, manufacturing and installing anchor cables, after drilling, manufacturing the anchor cables on a site which is cleaned in advance according to the blanking length, and installing the anchor cables in anchor cable holes which are drilled in advance;
s3a, anchor cable manufacturing, wherein the length of an anchor rod is determined according to drawing design requirements and soil layer conditions of a construction site, anchor cable manufacturing is carried out on a site cleaned in advance according to blanking length, and meanwhile, the length error of each stranded wire is controlled to be 10 cm;
s3b, installing the anchor cable, checking whether the serial number of the anchor cable is consistent with the serial number of the anchor cable before installing the anchor cable in the anchor cable hole, manually lifting the anchor cable to a working surface after the serial number of the anchor cable is confirmed to be correct, manually penetrating the anchor cable into the anchor hole smoothly, stopping penetrating the anchor cable when the exposed part meets the working length, and performing grouting work after the installation work of the anchor cable is finished;
s4, grouting construction, wherein the grouting material is pure cement slurry, cement is ordinary silicate 425, the water cement ratio is 0.5, 10% of UEA-Z type composite expanding agent and 0.6% of high-efficiency early-strength water reducing agent are additionally added, the slurry strength is not less than 40MPa, a grouting pipe is slowly drawn while grouting is carried out, the grouting pipe orifice is ensured to be positioned at the slurry level, the slurry is ensured to be dense and saturated, the designed slurry strength is reached, grouting can be stopped when clear slurry overflows from an orifice, relevant records are made in the grouting process, and test blocks are made;
s5, carrying out an anchor rod pullout resistance test, carrying out the pullout resistance test at an actual site after the strength of the anchor hole grouting body meets the design requirement, wherein in the test process, the used tension meter and the exposed part of the anchor rod are kept parallel, and meanwhile, the tension is carried out by keeping constant and slow tension;
s6, sealing the anchor, after backfilling is filled in place according to the procedures, tensioning and locking all anchor cables on the pile, monitoring the pile position when tensioning is needed each time, cutting off redundant steel strands by using a lifting sand turbine after prestress tensioning is completed, keeping the length of the steel strands to be 20cm, finally installing a protective cover on the anchor rod, filling grease for sealing the anchor, and keeping the pile surface neat and attractive after sealing the anchor;
s7, monitoring axial force, selecting representative anchor holes before applying the axial force of the anchor cable, installing special sensor elements at the selected anchor holes, installing anchors, measuring the change condition of the axial force of the anchor cable at different periods through applying and observing prestress, and accordingly carrying out relevant processing, wherein the reading of the axial force is observed corresponding to the soil filling condition and the pile body displacement condition.
2. The self-drilling anchor rod construction method for the pore diving deep foundation pit according to claim 1, wherein the calculation formula of the anchor rod of the step S3a for the layered rock is as follows:
L1＝C1+H+C2；
in the formula: l is1Length of rockbolt (a)m)；
C1The depth range of the anchor rod inserted into the hard rock is 250 mm-300 mm;
h, directly anchoring the wall rock to the thickness;
C2-anchor rod exposed length.
3. The self-drilling anchor rod construction method for the pore diving deep foundation pit according to claim 1, wherein the calculation formula of the anchor rod of the step S3a for the non-laminated rock is as follows:
Figure FDA0002728621500000031
in the formula: l is2-length of anchor rod (m) in non-stratified rock;
b-tunnel width (m).
4. The self-drilling anchor rod construction method for the pore submersible deep foundation pit according to claim 1, wherein the pressure range of grouting in the step S4 is 0.5-0.8 MPa.
5. The self-drilling anchor rod construction method for the pore submersible deep foundation pit according to claim 1, wherein the calculation formula of the grouting amount in the step S4 is as follows:
Q＝λπRLnβ；
in the formula: q-pressing amount of Single-hole slurry (m)3)；
Lambda is a loss coefficient, and 1.1-1.5 is taken;
r-slurry diffusion radius (m);
l is the length (m) of the grouting section;
n-volume fracture rate, taking 1-10% and broken zone taking 30-40%;
and taking 0.3-0.9 as the effective filling coefficient of the beta-slurry in the fracture.
CN202011111092.2A 2020-10-16 2020-10-16 Self-drilling anchor rod construction method for pore submersible deep foundation pit Pending CN112281836A (en)

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CN1536172A (en) * 2003-04-03 2004-10-13 诚 冯 Self-feeding type prestressed anchor rope and its construction method
CA2624690A1 (en) * 2005-11-09 2007-05-18 Steven Weaver Self drilling rock bolt
CN102286979A (en) * 2011-05-26 2011-12-21 昆明二建建设（集团）有限公司 Construction method for deep foundation pit supporting by adopting steel pipe piles-self-drilling prestressed anchor bars
CN109137893A (en) * 2018-07-24 2019-01-04 北京隧盾市政建设有限公司 Self-feeding anchor pile construction technology

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CN1536172A (en) * 2003-04-03 2004-10-13 诚 冯 Self-feeding type prestressed anchor rope and its construction method
CA2624690A1 (en) * 2005-11-09 2007-05-18 Steven Weaver Self drilling rock bolt
CN102286979A (en) * 2011-05-26 2011-12-21 昆明二建建设（集团）有限公司 Construction method for deep foundation pit supporting by adopting steel pipe piles-self-drilling prestressed anchor bars
CN109137893A (en) * 2018-07-24 2019-01-04 北京隧盾市政建设有限公司 Self-feeding anchor pile construction technology

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Application publication date: 20210129