CN113699968B - Self-expansion pile construction method for controlling subway operation shield tunnel settlement - Google Patents
Self-expansion pile construction method for controlling subway operation shield tunnel settlement Download PDFInfo
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- CN113699968B CN113699968B CN202111026354.XA CN202111026354A CN113699968B CN 113699968 B CN113699968 B CN 113699968B CN 202111026354 A CN202111026354 A CN 202111026354A CN 113699968 B CN113699968 B CN 113699968B
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
- E02D3/02—Improving by compacting
- E02D3/08—Improving by compacting by inserting stones or lost bodies, e.g. compaction piles
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- 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
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D3/00—Improving or preserving soil or rock, e.g. preserving permafrost soil
- E02D3/12—Consolidating by placing solidifying or pore-filling substances in the soil
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/22—Piles
- E02D5/34—Concrete or concrete-like piles cast in position ; Apparatus for making same
- E02D5/38—Concrete or concrete-like piles cast in position ; Apparatus for making same making by use of mould-pipes or other moulds
- E02D5/44—Concrete or concrete-like piles cast in position ; Apparatus for making same making by use of mould-pipes or other moulds with enlarged footing or enlargements at the bottom of the pile
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
- E21B49/02—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells by mechanically taking samples of the soil
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B7/00—Special methods or apparatus for drilling
- E21B7/02—Drilling rigs characterized by means for land transport with their own drive, e.g. skid mounting or wheel mounting
Abstract
The invention provides a self-expansion pile construction method for controlling the settlement of a subway operation shield tunnel, which comprises the following steps: 1) Exploration and sampling: drilling in a long-term settlement area after tunnel construction to take out a core, performing geotechnical test on the core to obtain physical and mechanical indexes of a sample and divide different soil layer ranges, determining the position burial depth of the top surface of a hard soil layer, and selecting grouting pressure P suitable for different types of soil layers Grouting (ii) a 2) Manufacturing a steel pipe and a circular geotextile bag: 21 Selecting a steel pipe matched with the drilled hole, and placing a circular geotextile bag and a steel pipe hoop by spacing a certain distance between the outer wall of the steel pipe and the inner wall of the drilled hole; 22 Dividing different soil layer ranges through exploration sampling analysis, and sequentially punching grouting ports on the outer side of the steel pipe according to the division of the soil layers; 23 A circular geotextile bag is sleeved outside the steel pipe; 3) Drilling a grouting hole by a drilling machine; 4) And (7) grouting construction.
Description
Technical Field
The invention relates to the field of tunnel construction, in particular to a construction method of a self-expansion pile for subway operation shield tunnel settlement.
Background
The subway shield tunnel is built in a soft soil stratum, long-term settlement which develops continuously exists after the shield tunnel is worked, and the most common disease forms in the long-term settlement of the tunnel include water damage, lining damage and unsmooth running. The tunnel water damage not only increases the humidity in the tunnel, causes accidents such as circuit short circuit, but also endangers the transportation safety. The tunnel will cause cracking of the lining or make the original cracks develop and grow larger due to water seepage and water leakage, and the cracking loss of the lining is aggravated. The long-term settlement of the tunnel causes the train to run unsmoothly. At present, there are many measures for controlling the subway shield tunnel settlement, such as enlarging the bearing area, increasing the primary support rigidity, adding an inverted arch, adding a foot locking steel pipe, grouting soft foundation, adding an anchor rod and the like. The bearing area is enlarged, the primary support rigidity is increased, the inverted arch is additionally arranged, the locking steel pipe is additionally arranged and the like are measures in the construction stage, the bearing capacity of a foundation is enhanced when a tunnel is excavated, a large space is needed, the soft foundation grouting is easy to be washed away by underground water flow, the effective reinforcing range cannot be guaranteed, and the addition of the anchor rod is complex in the drilling and installing processes, large in workload and long in time, and can influence the normal operation of a subway. However, the subway shield tunnel during operation cannot be excavated and repaired on a large scale, the space of the operating tunnel is small, large equipment cannot enter the repair, the shutdown time of the operation tunnel at night every day is short, and measures for controlling the subway sinking and reinforcing the soil body need to be guaranteed in a short time.
Chinese patent (application number: 202022270102.9, published as: 2020-10-13) discloses a steel pipe pile composite foundation structure for soft foundation treatment in a tunnel, which is suitable for the tunnel construction stage, and the formed steel pipe pile composite foundation improves the bearing capacity of the foundation by arranging a plurality of equally spaced submerged piles and deep piles, but slurry is directly injected into the piles, so that the grouting range cannot be controlled, the grouting range is easily washed away by underground water, the space required to be constructed is large, and the construction in a narrow operation shield tunnel cannot be carried out.
The above patent is only suitable for the construction stage of the subway tunnel, has large construction space, can not control slurry, and is contrary to the small excavation, short time and injectibility required by the subway operation shield tunnel.
Chinese patent (application number: 202110236605.0, published as: 2021-03-03) discloses a shield tunnel broken zone stratum grouting reinforcement device and a grouting reinforcement method thereof, wherein a small grouting device is used for injecting a back area and a deep grouting area of a shield segment, the two areas are sequentially grouted to reinforce the tunnel, the broken zone has strong water permeability, grouting cannot be controlled in the construction process, multiple times of grouting are needed, grouting quality cannot be guaranteed, and manpower and material resources are increased. Chinese patent (application number: 202010419966.4, published as: 2020-05-18) discloses a shield tunnel compaction grouting structure, which utilizes a grouting device composed of supporting legs and an adjustable grouting component to improve grouting efficiency and stability, but does not provide a reliable and stable grouting reinforcement method, and cannot ensure the reinforcement effect on a foundation. Chinese patent (application number: 201310554187.5, published as: 2013-11-11) discloses a soft soil foundation shield tunnel settlement control steel sleeve grouting reinforcement device, which utilizes a steel sleeve formed by connecting TAM units in series and combines an expansion type grout stop plug to perform grouting on a surrounding soil body at any burial depth, but the characteristics of the surrounding soil layer cannot be judged, corresponding grouting pressure is applied, and the grouting property of grout is reduced.
The above patent is applicable to the subway tunnel operation stage, does not all have fine controllability slip casting measure, extravagant manpower and materials to can not guarantee the quality of forming the pile body.
Chinese patent (application number: 201811252811.5, published as: 2018-10-25) discloses a method and equipment for reinforcing deep hole grouting in a shield tunnel, wherein a check valve is arranged in a grouting pipe, and a ball valve is arranged at the orifice of the grouting pipe to block the phenomena of underground water and slurry leakage, but a small and convenient grouting device is not provided, so that smooth grouting reinforcement cannot be guaranteed. Chinese patent (application number: 202011618835.5, published as: 2020-12-31) discloses a shield tunnel settlement control steel sleeve grouting reinforcement device, wherein an inner steel pipe and an outer steel pipe of a steel sleeve are separately grouted through a grouting assembly, the grouting length is extended, but no measure for controlling grouting amount is provided, and the quality of a formed miniature pile cannot be guaranteed.
The above patent is applicable to the subway operation stage, does not provide the slip casting reinforcement measure of system and the construction equipment of unobstructed function, can't guarantee the short-term high efficiency of slip casting and the quality of pile-forming.
Disclosure of Invention
The invention aims to provide a self-expansion pile construction method for controlling the settlement of a subway operation shield tunnel, which is used for effectively controlling the settlement of the subway operation shield tunnel and reinforcing soil around the shield tunnel.
In order to solve the technical problems, the technical scheme adopted by the invention for solving the problems is as follows:
a self-expansion pile construction method for controlling subway operation shield tunnel settlement comprises the following steps:
1) Exploration and sampling: drilling a long-term subsidence area after tunnel construction to take out a core, performing geotechnical test on the core to obtain physical and mechanical indexes of a sample and divide different soil layer ranges, determining the position burial depth of the top surface of a hard soil layer, adopting high-pressure grouting, and selecting grouting pressure P suitable for different soil layers according to a criterion formula according to data obtained by analyzing a soil sample Grouting (ii) a The criterion formula is as follows:
from the pore ratio versus pressure curves e-p, we obtain:
e＝e 0 -ap
P grouting ＝k 0 γ h + p wherein, s: soil layer compression amount e 0 : initial void fraction, e 1 : final porosity ratio, b: soil layer compression influence range, a: compression factor, k 0 : the static lateral pressure coefficient of the soil;
2) Manufacturing a steel pipe and a circular geotextile bag:
21 Selecting a steel pipe matched with the drilled hole, and placing a circular geotextile bag and a steel pipe hoop by spacing a certain distance between the outer wall of the steel pipe and the inner wall of the drilled hole;
22 Dividing different soil layer ranges through exploration sampling analysis, and sequentially punching grouting ports on the outer side of the steel pipe according to the division of the soil layers; manufacturing pipe joints at the positions of steel pipes at the junctions of the soil layers, placing rubber sealing rings in the pipe joints, and plugging the pipe joints by using round cakes made of PC (polycarbonate) plastics;
23 Round geotextile bags are sleeved outside the steel pipe, and a steel pipe hoop is sleeved at the joint of two adjacent round geotextile bags for fixation;
3) Drilling a grouting hole by a drilling machine: drilling the bottom of the grouting hole to be below the top surface of the hard soil layer;
4) Grouting construction: placing the manufactured steel pipe and the manufactured circular geotextile bag, and injecting paste slurry into the steel pipe by using the punching and grouting integrated machine; the paste slurry consists of more than or equal to 60 percent of coarse and fine aggregate graded stones and less than or equal to 40 percent of hardenable paste cement slurry.
In a preferred embodiment: step 4 comprises the following substeps:
41 When grouting, the first section of grouting is started from top to bottom, firstly a drilling machine is used for drilling a round cake made of PC plastic at a first pipe joint, then a grouting pipe is lowered to a grouting area, and grouting pressure is applied according to the properties of a soil layer; the grout flows into the first layer of circular geotextile bags from the grouting holes, and the round cakes at the second pipe joints are plugged so that the grout cannot flow into the second section of steel pipe;
42 After the first section of grouting is finished, pulling out the grouting pipe, and placing the steel bar coated with the concrete release agent in advance on the top surface of the second pipe section round cake along the position of the grouting pipe;
43 De-molding the reinforcing steel bars after the concrete is hardened, drilling holes along the holes by using a drilling machine, and repeating the steps 42 and 43; and finally, grouting the top section of the pile, taking out the grouting pipe, and repairing the pipe piece damaged by drilling.
In a preferred embodiment: the diameter of the steel pipe is 129mm.
In a preferred embodiment: the diameter of the grouting opening is 25mm, and the number of the grouting openings is not less than 20 per meter.
In a preferred embodiment: the pipe section is 50mm high, and 10mm wide.
In a preferred embodiment: the diameter of the round cake is smaller than that of the pipe joint, and the thickness of the round cake is smaller than the height of the pipe joint.
In a preferred embodiment: the diameter of the circular geotextile bag is 800mm.
In a preferred embodiment: and drilling the bottom of the grouting hole to a position 500mm below the top surface of the hard soil layer.
In a preferred embodiment: the distance between the grouting holes is 1500mm-2000mm, and the number of the grouting holes is 3 in the same tunnel cross section.
In a preferred embodiment: the high-pressure grouting pressure is 2MPa-3MPa.
Compared with the prior art, the construction method has the beneficial effects that:
1. the invention only needs a small-size appearance punching and grouting integrated machine 1480 multiplied by 680 multiplied by 1290 and a self-expansion pile consisting of a steel pipe and a circular geotextile bag, avoids large-area excavation and can be constructed in a shield tunnel space with numerous pipelines and narrow space.
2. The invention drills the small-diameter drill hole on the tunnel segment, reduces the damage to the prior segment, can form the large-diameter pile body, and achieves the purposes of controlling the settlement of the subway operation shield tunnel and reinforcing the soil body around the shield tunnel.
3. The grouting and punching integrated machine is provided with the adjustable four-wheel sliding chassis, the distance between the two wheels and the chassis of the drilling machine is adjusted, the grouting and punching integrated machine is matched with a standard track, the grouting and punching integrated machine can slide on a subway track, the movement of the grouting and punching integrated machine is efficiently completed, drilling and grouting are performed, the construction period is shortened, and the grouting and punching integrated machine is suitable for operation and outage time of the subway at night every day.
4. According to the invention, the steel pipe and the circular geotextile bag are placed in the drilled hole, the diameter of the pile body is enlarged through high-pressure grouting, the grouting range can be controlled, the large-diameter pile body is formed, the bearing area is increased, and the bearing capacity of the foundation is improved.
5. According to the invention, the soil sample is taken out, the physical and mechanical property indexes of the soil sample are obtained through soil engineering tests, the grouting pressures corresponding to different soil layers are designed and calculated according to a formula, and the targeted construction is carried out on the different soil layers in a targeted manner.
6. The method is combined with the condition of dynamic load after subway operation, calculates the bearing capacity and the settlement deformation of the foundation after design and construction, and is suitable for settlement control and calculation of the existing operation tunnel.
Drawings
FIG. 1 is a perspective view of the punching and grouting integrated machine;
FIG. 2 is a cross-sectional view of a self-expanding pile in a tunnel before grouting;
FIG. 3 is a cross-sectional view of a self-expanding pile in a tunnel after grouting;
FIG. 4 is a schematic view of a three-section self-expanding pile;
fig. 5 is a detail of the self-expanding pile in a large scale as in fig. 1;
fig. 6 is a detail of the self-expanding pile in a larger scale than fig. 2;
fig. 7 shows a detail of the self-expanding pile as in fig. 3.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention; it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art without any inventive work are within the scope of the present invention.
In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top/bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise specifically stated or limited, the terms "mounted," "disposed," "sleeved/connected," "connected," and the like, should be construed broadly, such as "connected," which may be wall-mounted, detachable, or integrally connected, mechanically connected, electrically connected, directly connected, indirectly connected through an intermediate medium, or connected between two elements.
Referring to fig. 1 to 7, the present embodiment provides a self-expanding pile construction method for controlling the settlement of a shield tunnel in subway operation, including the following steps:
1) And (6) exploration sampling. In a long-term settlement area after tunnel construction, a small-caliber diamond drill bit is used for drilling a core, a soil sample is subjected to related geotechnical tests, main physical and mechanical indexes of the sample, such as compactness, compression modulus, shear strength and the like of the soil sample, different soil layer ranges are divided, the burial depth of the top surface of a hard soil layer is determined, and the hard soil layer is completely weathered granite. Adopting high-pressure grouting with the grouting pressure of 2-3 MPa, and determining the grouting pressure and controlled grouting of different soil layers according to the data obtained by analyzing the soil sample by the following criterion formula:
from the pore ratio-pressure curve e-p, obtaining
e＝e 0 -ap
P Grouting ＝k 0 γh+p
Wherein, s: soil layer compression amount, e 0 : initial void fraction, e 1 : final porosity ratio, b: soil layer compression influence range, a: compression factor, k 0 : the static lateral pressure coefficient of the soil.
2) A steel pipe 1 and a circular geotextile bag 2 are manufactured. Selecting a seamless steel pipe 1 matched with a drilled hole, taking the steel pipe 1 with the diameter of 129mm, placing a circular geotextile bag 2 and a steel pipe hoop ring 3 between the steel pipe 1 and the hole in a reserved space, dividing different soil layer ranges through exploration, sampling and analysis, sequentially punching grouting openings on the outer side of the steel pipe 1 according to the division of soil layers, wherein the diameter of the grouting openings is 25mm, the number of the grouting openings needs to meet the grouting amount with large volume in a short time, the number of the openings is not less than 20/m, the grouting openings are uniformly distributed along the periphery of the steel pipe 1, pipe joints 4 with the height of 50mm and the width of 10mm are manufactured at the positions of the steel pipe 1 at the soil layer junction, rubber seal rings 5 are arranged in the pipe joints 4, circular cakes 6 made of PC plastic are used for plugging the pipe joints 4, the diameter of the circular cakes 6 is slightly smaller than the diameter of the pipe joints 4, the thickness of the pipe joints is slightly smaller than the height of the pipe joints 4, the manufactured circular cakes 6 are just used for plugging the pipe joints 4, the circular geotextile bag 2 specified according to design requirements is sleeved on the steel pipe 1, and the circular geotextile bag 2 with the diameter of 800mm is connected with the geotextile bag 2, and the pipe hoop ring 3, so as to prevent the excess grouting pressure from being punched.
3) And drilling a grouting hole by a drilling machine. The invention uses a small-size overall punching and grouting machine 7 of 1480 multiplied by 680 multiplied by 1290 to realize punching and grouting in a narrow space, an adjustable four-wheel sliding chassis is arranged at the bottom of the punching and grouting machine, the machine can slide on a subway track, and the movement of the machine can be efficiently completed during the operation and rest time. The drilling and grouting integrated machine 7 adjusts the angle of the drilling machine to drill a drill hole with the diameter of 150mm, the hole bottom is drilled to the position 500mm below the top surface of the hard soil layer, the distance between grouting holes is 1500mm-2000mm and the number of the grouting holes is 3 according to the design requirement by combining the grouting influence range and the cross section of the same tunnel.
4) And (7) grouting construction. Placing the manufactured steel pipe 1 and the circular geotextile bag 2, preparing paste slurry according to a certain material mixing ratio, wherein the paste slurry consists of more than or equal to 60 percent of coarse and fine aggregate graded stones and less than or equal to 40 percent of hardenable paste cement slurry, and injecting the paste slurry into the steel pipe 1 by utilizing the punching and grouting integrated machine 7.
41 Starting a first section of grouting from top to bottom, firstly opening a round cake 6 made of PC plastics at a first pipe joint 4 by using a punching and grouting integrated machine 7, drilling to obtain a hole diameter of 110mm, then lowering a grouting pipe 8 to a grouting area, wherein the diameter of the grouting pipe 8 is 50mm, starting to apply certain grouting pressure according to the soil property, the high-pressure grouting pressure is at least more than 1.5MPa, considering the shearing resistance of the circular geotextile bags 2 and a soil body, the highest grouting pressure is not more than 10MPa, enabling the grout to flow into the first layer of circular geotextile bags 2 from a grouting hole, enabling the round cake 6 at a second pipe joint 4 to seal the grout to flow into a second section of steel pipe 1, injecting the grout to expand the circular geotextile bags 2 of the pile body and extrude the stratum, performing controlled grouting by calculating the volume of the circular geotextile bags 2 of the pile body after expansion, and stopping the grouting when the compactness of the soil body reaches 90% or the grouting reaches 90% of the calculated volume.
42 After the first section of grouting is finished, the grouting pipe 8 is pulled out, the 100mm steel bar 9 coated with the concrete release agent in advance is placed on the top surface of the round cake 6 of the second pipe joint 4 along the position of the grouting pipe 8, and the construction of the first day is finished. The next day, the concrete hardens, the concrete release agent is smeared on the outer layer of the steel bar 9, and the grout can be easily released after initial setting.
43 Repeating the steps 41 and 42, finally completing the grouting of the pile top section, taking out the grouting pipe 8, and repairing the segment damaged by drilling.
5) And (4) calculating the bearing capacity of the pile body. The soft soil foundation treated by the self-expansion pile construction method for effectively controlling the settlement of the subway operation shield tunnel is classified into a flexible pile composite foundation to determine the foundation bearing capacity according to the used materials and the actual strength of the pile body during calculation. According to the technical specification of building pile foundation JGJ94-2008, the bearing capacity of the post-grouting cast-in-place pile is improved, and the bearing capacity of the composite foundation is as follows:
f a ＝f ak η b γ(b-3)+η d γ m (d-0.5)
f (t): is a line load evenly distributed along the track centerline. P (t): the vertical load of the steel rail is measured actually. N is a radical of b : the number of bogies per vehicle. n is w : the number of wheel pairs for each bogie. L: is the vehicle length. k: generally, the value is 0.6 to 0.9 according to experience. Q sk : and (4) standard value of total limit side resistance of the post-grouting non-vertical reinforcement section. Q gsk : and (4) a total limit side resistance standard value of the rear grouting vertical reinforcing section. Q gpk : and (5) a standard value of resistance of the total limit end of post grouting. u: the perimeter of the pile body. l j : and (5) grouting the thickness of the jth layer of soil of the non-vertical reinforced section. l. the gi : the thickness of the ith layer soil in the post-grouting vertical reinforcement section is 12m above the pile end when the single pile end is post-grouted for the slurry retaining wall pore-forming cast-in-place pile; when the pile end and the pile side are subjected to compound grouting, the vertical reinforcing section is 12m above the pile end and 12m above the grouting section of each pile side, and the overlapped part is deducted; for the dry operation cast-in-place pile, the vertical reinforced section is above the pile end and 6m above and below the pile side grouting section. q. q.s sik 、q sjk 、q pk : the standard value of the initial limit lateral resistance of the ith soil layer of the post-grouting vertical reinforcing section, the standard value of the initial limit lateral resistance of the jth soil layer of the non-vertical reinforcing section and the standard value of the initial limit end resistance are respectively determined according to 5.3.5 of the specification. Beta is a beta si 、β p : the coefficients of the side resistance and the end resistance of the post-grouting are respectively, and when no local experience exists, the values can be taken according to the table 5.3.10. For the pile with the pile diameter larger than 800mm, the size effect correction of the side resistance and the end resistance is carried out according to the specification table 5.3.6-2.
And (4) calculating the deformation of the composite foundation, wherein the calculation is carried out according to the pile foundation with the pile center distance not more than 6 times of the pile diameter in JGJ 94-2008. The deformation formula is as follows:
psi: the empirical coefficient of pile foundation settlement is calculated, and when the empirical is not reasonably reliable, the empirical coefficient can be determined according to 5.5.11 of the specification. Psi c : the equivalent settlement coefficient of the foundation of the pile can be determined according to 5.5.9 of the specification. p is a radical of 0 : the average additional pressure of the base of the bearing platform under the quasi-permanent combination of loading effects.
Mean additional stress factor according to rectangular aspect ratio a/b and aspect ratio Z i /b＝2Z i /B c And can be selected according to the annex D of the specification. E si : the compression modulus (MPa) of the i-th layer of soil below the equivalent action surface is the compression modulus of the foundation soil under the action of the gravity pressure to the gravity pressure plus the additional pressure. Z i 、Z i-1 : the average additional stress coefficient from the pile end plane load calculation point to the depth range of the ith layer of soil and the ith-1 layer of soil bottom surface can be selected according to the appendix D of the specification.
In this embodiment, the punching and grouting all-in-one machine 7 includes a chassis 71, and four wheels 74 arranged on the chassis 71; a body 72 provided on an upper surface of the chassis; the side of the body 72 is connected with a motor 73, and the body 72 is also connected with the grouting pipe 8 through a gyrator assembly 75.
The above description is only a preferred embodiment of the present invention, but the design concept of the present invention is not limited thereto, and any person skilled in the art can make insubstantial changes in the technical scope of the present invention within the technical scope of the present invention, and the actions infringe the protection scope of the present invention are included in the present invention.
Claims (10)
1. A self-expansion pile construction method for controlling subway operation shield tunnel settlement is characterized by comprising the following steps:
1) Exploration and sampling: drilling a long-term subsidence area after tunnel construction to take out a core, performing geotechnical test on the core to obtain physical and mechanical indexes of a sample and divide different soil layer ranges, determining the position burial depth of the top surface of a hard soil layer, adopting high-pressure grouting, and selecting grouting pressure P suitable for different soil layers according to a criterion formula according to data obtained by analyzing a soil sample Grouting (ii) a The criterion formula is as follows:
from the pore ratio versus pressure curves e-p, we obtain:
e＝e 0 -ap
P grouting ＝k 0 γh+p
Wherein, s: soil layer compression amount e 0 : initial void fraction, e 1 : final porosity ratio, b: soil layer compression influence range, a: compression factor, k 0 : the static lateral pressure coefficient of the soil;
2) Manufacturing a steel pipe and a circular geotextile bag:
21 Selecting a steel pipe matched with the drilled hole, and placing a circular earthwork bag and a steel pipe hoop by spacing a certain distance between the outer wall of the steel pipe and the inner wall of the drilled hole;
22 Dividing different soil layer ranges through exploration, sampling and analysis, and sequentially punching grouting openings on the outer side of the steel pipe according to the division of the soil layers; manufacturing pipe joints at the positions of steel pipes at the junctions of the soil layers, placing rubber sealing rings in the pipe joints, and plugging the pipe joints by using round cakes made of PC (polycarbonate) plastics;
23 Round geotextile bags are sleeved outside the steel pipe, and a steel pipe hoop is sleeved at the joint of two adjacent round geotextile bags for fixation;
3) Drilling a grouting hole by a drilling machine: drilling the bottom of the grouting hole to be below the top surface of the hard soil layer;
4) Grouting construction: placing the manufactured steel pipe and the manufactured circular geotextile bag, and injecting paste slurry into the steel pipe by using the punching and grouting integrated machine; the paste slurry consists of more than or equal to 60 percent of coarse and fine aggregate graded stones and less than or equal to 40 percent of hardenable paste cement slurry.
2. The self-expansion pile construction method for controlling the settlement of the shield tunnel for subway operation according to claim 1, characterized in that: step 4 comprises the following substeps:
41 When grouting, the first section of grouting is started from top to bottom, firstly a drilling machine is used for drilling a round cake made of PC plastic at a first pipe joint, then a grouting pipe is lowered to a grouting area, and grouting pressure is applied according to the properties of a soil layer; the grout flows into the first layer of circular geotextile bags from the grouting holes, and the round cakes at the second pipe joints are plugged so that the grout cannot flow into the second section of steel pipe;
42 After the first section of grouting is finished, pulling out the grouting pipe, and placing the steel bar coated with the concrete coating agent in advance on the top surface of the second pipe section round cake along the position of the grouting pipe;
43 De-molding the reinforcing steel bars after the concrete is hardened, drilling holes along the holes by using a drilling machine, and repeating the steps 42 and 43; and finally, grouting the top section of the pile, taking out the grouting pipe, and repairing the segment damaged by drilling.
3. The self-expansion pile construction method for controlling the settlement of the shield tunnel for subway operation according to claim 1, characterized in that: the diameter of the steel pipe is 129mm.
4. The self-expansion pile construction method for controlling the settlement of the subway operation shield tunnel according to claim 1, characterized in that: the diameter of the grouting opening is 25mm, and the number of the grouting openings is not less than 20 per meter.
5. The self-expansion pile construction method for controlling the settlement of the subway operation shield tunnel according to claim 1, characterized in that: the pipe section is 50mm high, wide 10mm.
6. The self-expansion pile construction method for controlling the settlement of the shield tunnel for subway operation according to claim 1, characterized in that: the diameter of the round cake is smaller than that of the pipe joint, and the thickness of the round cake is smaller than the height of the pipe joint.
7. The self-expansion pile construction method for controlling the settlement of the shield tunnel for subway operation according to claim 1, characterized in that: the diameter of the circular geotextile bag is 800mm.
8. The self-expansion pile construction method for controlling the settlement of the shield tunnel for subway operation according to claim 1, characterized in that: and drilling the bottom of the grouting hole to a position 500mm below the top surface of the hard soil layer.
9. The self-expansion pile construction method for controlling the settlement of the shield tunnel for subway operation according to claim 1, characterized in that: the distance between the grouting holes is 1500mm-2000mm, and the number of the grouting holes is 3 in the same tunnel cross section.
10. The self-expansion pile construction method for controlling the settlement of the subway operation shield tunnel according to claim 1, characterized in that: the high-pressure grouting pressure is 2MPa-3MPa.
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| US10760236B2 (en) * | 2017-12-15 | 2020-09-01 | Redrock Ventures B.V. | System and method for real-time displacement control using expansive grouting techniques |
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