CN111287763B - Control method for preventing subway shield tunnel from long-term settlement - Google Patents
Control method for preventing subway shield tunnel from long-term settlement Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 68
- 230000007774 longterm Effects 0.000 title claims abstract description 18
- 238000003825 pressing Methods 0.000 claims abstract description 58
- 239000002689 soil Substances 0.000 claims abstract description 56
- 238000010276 construction Methods 0.000 claims abstract description 45
- 238000005553 drilling Methods 0.000 claims abstract description 35
- 230000001360 synchronised effect Effects 0.000 claims abstract description 6
- 238000003466 welding Methods 0.000 claims description 64
- 238000013461 design Methods 0.000 claims description 15
- 238000009434 installation Methods 0.000 claims description 15
- 229910000831 Steel Inorganic materials 0.000 claims description 12
- 239000004567 concrete Substances 0.000 claims description 12
- 239000010959 steel Substances 0.000 claims description 12
- 238000011065 in-situ storage Methods 0.000 claims description 10
- 238000007689 inspection Methods 0.000 claims description 10
- 230000005540 biological transmission Effects 0.000 claims description 9
- 238000012937 correction Methods 0.000 claims description 9
- 230000002787 reinforcement Effects 0.000 claims description 7
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 6
- 230000035515 penetration Effects 0.000 claims description 6
- 239000011513 prestressed concrete Substances 0.000 claims description 6
- 230000003068 static effect Effects 0.000 claims description 6
- 238000012360 testing method Methods 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 238000009412 basement excavation Methods 0.000 claims description 4
- 241000357293 Leptobrama muelleri Species 0.000 claims description 3
- 238000005452 bending Methods 0.000 claims description 3
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 3
- 239000001569 carbon dioxide Substances 0.000 claims description 3
- 238000004891 communication Methods 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 3
- 238000005520 cutting process Methods 0.000 claims description 3
- 238000006073 displacement reaction Methods 0.000 claims description 3
- 238000010891 electric arc Methods 0.000 claims description 3
- 238000011835 investigation Methods 0.000 claims description 3
- 239000002932 luster Substances 0.000 claims description 3
- 238000005259 measurement Methods 0.000 claims description 3
- 238000012544 monitoring process Methods 0.000 claims description 3
- 238000001556 precipitation Methods 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 3
- 238000004904 shortening Methods 0.000 claims description 3
- 239000002893 slag Substances 0.000 claims description 3
- 238000005286 illumination Methods 0.000 claims description 2
- 238000005527 soil sampling Methods 0.000 claims 2
- 238000007599 discharging Methods 0.000 claims 1
- 239000002184 metal Substances 0.000 claims 1
- 238000004062 sedimentation Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000011150 reinforced concrete Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/003—Linings or provisions thereon, specially adapted for traffic tunnels, e.g. with built-in cleaning devices
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D27/00—Foundations as substructures
- E02D27/32—Foundations for special purposes
- E02D27/48—Foundations inserted underneath existing buildings or constructions
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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
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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
- E02D5/50—Piles comprising both precast concrete portions and concrete portions cast in situ
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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
- E02D5/58—Prestressed concrete piles
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
- E21D11/105—Transport or application of concrete specially adapted for the lining of tunnels or galleries ; Backfilling the space between main building element and the surrounding rock, e.g. with concrete
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D2250/00—Production methods
- E02D2250/0023—Cast, i.e. in situ or in a mold or other formwork
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Abstract
The invention discloses a control method for preventing subway shield tunnel from long-term settlement, which is implemented in a shield tunnel, wherein a hole is drilled at the bottom of a duct piece through a middle digging construction method by relative rotation of an outer sleeve and a spiral drill rod in the outer sleeve, one power head drives the spiral drill rod to perform spiral drilling, the other power head drives the outer sleeve to sink and to synchronously follow the spiral drill rod to descend, a hydraulic jacking work station or a jacking pile sinking device or a holding type pile sinking device is utilized to jack the outer sleeve into a soil body below the duct piece one by one in the shield tunnel, and the rotary drilling of the spiral drill rod in the outer sleeve discharges the soil body in a pile pressing range into the shield tunnel continuously, so that the synchronous sinking of the outer sleeve and the spiral drill rod is realized. Has the advantages that: the load of the subway tunnel in the operation period is transmitted to the soil layer with higher bearing capacity through the formed pile body, so that the long-term settlement of the subway tunnel in the operation period is reduced and prevented. The construction operation is simple and convenient, the equipment is less, and the construction cost is low.
Description
Technical Field
The invention relates to a control method for preventing settlement, in particular to a control method for preventing long-term settlement of a subway shield tunnel.
Background
At present, any building (structure) can generate settlement in the construction and use processes, and the settlement generated in the use process is also called post-construction or long-term settlement. Excessive long-term settlement may affect the normal use of the building or structure or even compromise its safety. At present, the construction of urban subway tunnels by a shield method is vigorous, subway shield tunnels of many cities have been operated for more than 20 years, and the subway shield tunnels can generate long-term settlement during operation, particularly the long-term settlement amount of the subway shield tunnels in soft soil can account for 30% -90% of the total settlement amount. When the shield tunnel has too much settlement or longitudinal deformation curvature (also uneven settlement) reaches a certain value, the annular seam of the segments of the shield tunnel is too large, so that the phenomenon of water seepage and mud seepage is caused, or the segments are damaged by tension, the subway track is caused to generate distortion deformation, and the comfort and the safety of the subway train during operation are influenced. At present, most of subway shield tunnels operated for a long time are shallow in buried depth, generally 15m-30m below the earth surface, and the stratum with the depth is generally soft soil layers and other soil layers with poor bearing capacity, so that the subway shield tunnels are easy to generate long-term settlement in the operation period. One of the solutions to solve the above problems is to transfer the load of the subway shield tunnel in the operation period to the deeper soil layer with better bearing capacity below the subway shield tunnel.
Chinese patent "a method for controlling settlement of an operating subway tunnel" (CN 102733413A) discloses a method for controlling settlement of an operating subway tunnel, which comprises the steps of excavating vertical working wells at two sides of the operating subway tunnel to reach the elevation of the bottom of the tunnel, then carrying out construction of cast-in-situ bored piles or prestressed pipe piles in the working wells at the two sides, and enabling the bottoms of the cast-in-situ bored piles or the prestressed pipe piles to fall on a soil layer with high bearing capacity below a shield tunnel; and then, constructing a transverse reinforced concrete top beam at the bottom elevation of the tunnel, forming a portal supporting structure of the subway operation tunnel together with the cast-in-situ bored piles or prestressed pipe piles at two sides of the beam, and finally backfilling a working well. The method can effectively prevent the long-term settlement of the subway shield tunnel under the support of the portal support structure, but the method has the advantages of large earthwork workload, long construction period and high construction cost. How to find a method for economically and rapidly reducing and preventing the long-term settlement of the subway shield tunnel is a key technical problem to be solved urgently at present.
Disclosure of Invention
The invention aims to provide a control method for preventing a subway shield tunnel from long-term sedimentation, which aims to solve the problem of long-term sedimentation of the subway shield tunnel.
The invention provides a control method for preventing a subway shield tunnel from long-term sedimentation, which comprises the following steps:
the construction method comprises the steps that during construction in a shield tunnel, relative rotation of an outer sleeve and a spiral drill rod inside the outer sleeve is conducted on the bottom of a duct piece through a middle digging construction method to conduct drilling, one power head drives the spiral drill rod to conduct spiral drilling, the other power head drives the outer sleeve to sink, the outer sleeve and the spiral drill rod synchronously follow up to descend, the outer sleeve is jacked into soil below the duct piece in a section by section through a hydraulic jacking work station or jacking pile sinking or holding type pile sinking equipment inside the shield tunnel, and the soil within a pile pressing range is continuously discharged into the shield tunnel through rotary drilling of the spiral drill rod inside the outer sleeve, so that synchronous sinking of the outer sleeve and the spiral drill rod is achieved.
The outer sleeve is of a pipe pile structure and is a prefabricated prestressed concrete pipe pile or a steel sleeve prefabricated on site, the outer sleeve needs to be put down section by section, the length of each section of the outer sleeve is 1-3m, and the diameter of each section of the outer sleeve is 0.5-1 m.
The spiral drill rod is also assembled and drilled in sections like the outer sleeve, the length of each section of the spiral drill rod is consistent with that of the outer sleeve, the diameter of each section of the spiral drill rod is smaller than the inner diameter of the outer sleeve, when the spiral drill rod is drilled to a preset depth, concrete can be continuously poured in along with the spiral drill rod, a reinforcement cage is inserted in sections, a lower pile body of segments such as a prestressed concrete pipe pile or a steel pipe pile or a cast-in-situ bored pile is finally formed, then the lower pile body and the segments are cast in place, the load of the subway tunnel in the operation period is transmitted to a soil layer with higher bearing capacity through the formed pile body, and the lower pile body is arranged at intervals of 100-500 m along the longitudinal direction.
The concrete construction process of the method is as follows:
first step, early preparation: before engineering construction, determining a construction process according to a geological survey report, performing supplementary survey if necessary, performing geological survey within 5m of each of two sides of an axis of a pipe pile, checking whether the geology is consistent with the design, and checking whether existing buildings or pipelines exist nearby, if the geology is inconsistent with the design or has bad geology, enlarging the survey range, contacting with a design unit, and taking treatment measures;
secondly, measuring, positioning and equipment installation: according to known control points and elevations, accurately measuring and placing the position elevation and the axis of the positioning tubular pile, and according to the installation position of the measuring and placing equipment, a guide rail, a jack support, a backrest and a spiral drilling machine must be accurately and firmly arranged to ensure that subsequent construction is smoothly carried out, the equipment needs to be trial run before formal construction, formal construction can be carried out after performance requirements are met, and the following points are mainly paid attention to:
1) the installation of the pile pressing equipment and the soil taking equipment must ensure that the axes of the pile pressing equipment and the soil taking equipment are coincident;
2) the back rest adopts an integral steel back and directly leans against the pipe sheet, and the back rest is required to be perpendicular to the axis of the pile when being placed;
3) the installation of the jack and the guide rail ensures that the center position of the jack is superposed with the axis of the pile, and also ensures that the elevation meets the design requirement;
4) the guide rail and the jack support must be firmly reinforced, so that pile pressing deviation caused by the influence on the transmission of pressure due to displacement in the pile pressing process is prevented;
thirdly, opening a duct piece at the bottom of the tunnel, pressing the duct piece into the soil, and positioning the spiral drill rod: before the auger stem drills, all equipment is comprehensively checked, including whether a hydraulic system, an electric system, a mud jacking system, an illumination system, a communication system, a motor system, an oil pump system and a pipeline operation system can work normally or not, whether various electric meters, pressure meters and reversing valves display the working states of the electric meters and the pressure meters correctly or not is judged, whether the equipment installation positions are accurate or not is carefully checked at the same time, linkage debugging is carried out, and after the situation that no fault exists is confirmed, drilling soil taking and pile pressing construction can be started after a person in charge checks and signs the intention;
before the auger stem drills, the drilling deviation is strictly controlled, and the deviation of the central axis is not more than 10 mm;
step four, operating the spiral drill rod to take out soil and simultaneously pressing the tubular pile: when the auger stem drills and fetches earth, the tubular pile is pressed down through the jack, and synchronous sinking of the auger stem and the tubular pile is guaranteed;
in the initial stage of drilling of the spiral drill rod, a deviation rectifying oil cylinder is used as little as possible, so that the accuracy of the height and the left and right of the tubular pile is kept;
when piping, collapsed soil and a large amount of water are gushed, precipitation and grouting reinforcement measures are adopted, and drilling is continued after treatment is finished;
in the whole process of drilling and pressing down, the measurement work is strengthened, the direction and height of errors are corrected by adopting different soil excavation amounts and deviation correcting oil cylinders, the principle of 'measuring and correcting on duty' is adhered to, the deviation correcting angle is kept at 10 '-20' and is not more than 1 degree, the deviation correction is carried out step by step, and the principle of 'slow correction and slow correction' is adhered to;
adjusting pile pressing speed at any time according to pressure change and deviation conditions in the pile pressing process, wherein the speed is controlled to be 50mm/min and not more than 70mm/min at most;
the pile pressing equipment can also select top pressing type pile sinking equipment or holding type pile sinking equipment besides a jack, the type and the balance weight of the pile pressing machine are selected according to design requirements and investigation reports or pile testing data, the pile sinking site of the static pressure method meets the requirements of the grounding pressure of the pile pressing machine, and various conditions in the pile sinking process are recorded in the pile pressing process, including pile pressing time, pile position numbers, pile body quality, soil penetration depth and corresponding pressure readings;
the pile sinking process meets the following requirements:
1) the verticality deviation of the pile is not more than 0.5%;
2) when the pile is pressed, the pile pressing machine is kept horizontal, and the holding pressure is not more than 1.1 times of the allowed lateral pressure of the pile body;
3) continuously sinking the pile to the designed elevation at one time, shortening the intermediate pause time as much as possible and avoiding pile splicing when approaching a bearing stratum;
in the static pressure method construction process, the control quality of the final pressure standard condition is determined according to the experimental result of the on-site pile test, and the preset final pressure standard can take a single pile bearing capacity characteristic value of 1.5-1.8;
fifthly, placing the next section of tubular pile and the spiral drill rod: after the pressure stroke of each section of tubular pile is finished and the jack is retracted, the next section of tubular pile can be installed, the auger stem and each section of tubular pile are rigidly connected, and the force transmission of the auger stem and the tubular pile is ensured;
before each section of tubular pile and the spiral drill rod are installed, firstly, quality inspection is carried out, the tubular pile can be installed after the tubular pile and the spiral drill rod are qualified, when the tubular pile is aligned with the opening, the tubular pile is hung on a track and is stable, the spigot end of the tubular pile is aligned with the socket end of the front pipe, the tubular pile is slowly pressed in, then, the tubular pile is connected in a welding rigid connection mode, drilling and soil removal need to be temporarily stacked on the site, the distance from the pile edge during stacking is at least not less than 3m, the soil stacking height cannot be more than 2m, the soil is timely transported away, and excessive soil stacking cannot be achieved;
in the pipe pressing process, corresponding monitoring and protection measures are taken for underground buildings such as water, gas pipes, cables and the like within the range of 10m on the periphery;
the welding pile shall meet the following regulations besides the regulations of the secondary welding seam in the current national standard:
1) the pile head of the pile section of the soil entering part is higher than the bottom of the pipe piece by 1.0 m;
2) the pile head of the lower pile is provided with a guide hoop or other guide measures, the upper pile section and the lower pile section are kept straight and staggered by no more than 2mm during pile splicing, and the bending rise of a node is not more than 1/1000 pile length and not more than 20mm during pile splicing section by section;
3) the bevels of the upper pile joint end plate and the lower pile joint end plate are clean and dry, and the welding part is brushed until the metallic luster is exposed;
4) when manual welding is carried out, firstly, 4-6 points are symmetrically spot-welded on the periphery of the groove, after the upper pile section and the lower pile section are fixed, the guide hoop is removed, and then layered welding is carried out, wherein the welding is carried out symmetrically;
5) the number of welding layers is not less than 2, the outer layer can be welded after the inner layer welding slag is cleaned up, and the welding seam is full and continuous;
6) when in manual electric arc welding, the first layer is preferably welded by a welding rod with the diameter of 3.2mm to ensure the root penetration, and the second layer can be a thick welding rod, preferably an E43 type series welding rod; when carbon dioxide gas is adopted for shielded welding, the welding wire is preferably ER50-6 type;
7) after the pile joint is welded, appearance inspection is carried out, pile sinking can be continued after the inspection is qualified, and watering and cooling are strictly forbidden;
8) welding the steel pile tip or the concrete pile tip in a factory; when welding is carried out on a construction site, welding is carried out on a stacking site, and the methods of spot welding and overhead welding after pile hoisting are strictly forbidden;
when the precast pile adopts a mechanical connection mode, the operation requirement of the corresponding mechanical connection mode is required to be met;
the precast pile cutting adopts a special pile sawing machine, and a large hammer is strictly forbidden to transversely knock and cut the pile or forcibly pull and pull the pile;
sixthly, the pile and the shield tunnel are cast in place into a whole: the back is withdrawed to auger stem a lesson, finally is in the same place tubular pile and tunnel section of jurisdiction cast in situ for tubular pile and shield tunnel connect into a whole, finally realize the effective transmission of subway operation period load, also can make the tubular pile into the drilling bored concrete pile, can pour into the concrete in succession along with auger stem when proposing promptly, the subdivision inserts the steel reinforcement cage.
The invention has the beneficial effects that:
the control method for preventing the subway shield tunnel from settling for a long time is to construct in the shield tunnel, drill holes on the bottom of a tunnel segment by relative rotation of an outer sleeve (a concrete pipe pile or a steel sleeve) and a spiral drill rod in the outer sleeve through a middle digging method, drive the spiral drill rod to carry out spiral drilling by one power head, drive the outer sleeve to sink by the other power head, and synchronously follow the spiral drill rod to descend. The invention is similar to the construction of a pipe jacking method, the outer sleeve always goes along with the inner spiral drill pipe to sink in the construction process, and the outer sleeve plays the roles of stabilizing the existing shield tunnel, protecting the wall, preventing hole collapse and helping the spiral drill pipe to transport and dig the soil body in the drilling process. The finally formed prestressed concrete pipe pile, the steel pipe pile or the cast-in-place pile body under the pipe pieces is cast with the pipe pieces together, and the load of the subway tunnel in the operation period is transmitted to the soil layer with higher bearing capacity through the formed pile body, so that the long-term settlement of the subway tunnel in the operation period is reduced and prevented. The method has the advantages of less earthwork excavation, less operating personnel, no influence on traffic and buildings (structures) thereon, simple and convenient construction operation, less equipment, low construction cost, quick construction progress and the like.
Drawings
Fig. 1 is a schematic view of the position structure of the lower pile body.
FIG. 2 is a process flow diagram of the method of the present invention.
The labels in the above figures are as follows:
1. shield tunnel 2, section of jurisdiction 3, outer tube 4, auger stem.
Detailed Description
Please refer to fig. 1 to 2:
the invention provides a control method for preventing a subway shield tunnel from long-term sedimentation, which comprises the following steps:
the construction method comprises the steps that construction is carried out in a shield tunnel 1, relative rotation of an outer sleeve 3 and a spiral drill rod 4 inside the outer sleeve 3 is carried out on the bottom of a duct piece 2 through a middle digging method to drill, one power head drives the spiral drill rod 4 to carry out spiral drilling, the other power head drives the outer sleeve 3 to sink down and synchronously follow the spiral drill rod 4 to descend, the outer sleeve 3 is jacked into soil below the duct piece 2 in the shield tunnel 1 section by section through a hydraulic jacking work station or jacking pile sinking or holding type pile sinking equipment, and the soil in a pile pressing range is continuously discharged into the shield tunnel 1 through rotary drilling of the spiral drill rod 4 inside the outer sleeve 3, so that synchronous sinking of the outer sleeve 3 and the spiral drill rod 4 is achieved.
The outer sleeve 3 is a pipe pile structure and is a prefabricated prestressed concrete pipe pile or a steel sleeve prefabricated on site, the outer sleeve 3 needs to be put down section by section, the length of each section of the outer sleeve 3 is 1-3m, and the diameter of each section of the outer sleeve 3 is 0.5-1 m.
The auger stem 4 is also assembled and drilled in sections like the outer sleeve 3, the length of each section of the auger stem 4 is consistent with that of the outer sleeve 3, the diameter of each section of the auger stem is smaller than the inner diameter of the outer sleeve 3, when the auger stem 4 is drilled to a preset depth, concrete can be continuously poured in along with the auger stem 4, then a reinforcement cage is inserted in sections, the lower pile bodies of the segments 2 of the prestressed concrete pipe pile or the steel pipe pile or the cast-in-situ bored pile are finally formed, then the lower pile bodies and the segments 2 are cast in situ together, the load of the subway tunnel in the operation period is transmitted to a soil layer with higher bearing capacity through the formed pile bodies, and the lower pile bodies are arranged one by one at intervals of 100m-500 m.
The concrete construction process of the method is as follows:
first step, early preparation: before engineering construction, determining a construction process according to a geological survey report, performing supplementary survey if necessary, performing geological survey within 5m of each of two sides of an axis of a pipe pile, checking whether the geology is consistent with the design, and checking whether existing buildings or pipelines exist nearby, if the geology is inconsistent with the design or has bad geology, enlarging the survey range, contacting with a design unit, and taking treatment measures;
secondly, measuring, positioning and equipment installation: according to known control points and elevations, accurately measuring and placing the position elevation and the axis of the positioning tubular pile, and according to the installation position of the measuring and placing equipment, a guide rail, a jack support, a backrest and a spiral drilling machine must be accurately and firmly arranged to ensure that subsequent construction is smoothly carried out, the equipment needs to be trial run before formal construction, formal construction can be carried out after performance requirements are met, and the following points are mainly paid attention to:
1) the installation of the pile pressing equipment and the soil taking equipment must ensure that the axes of the pile pressing equipment and the soil taking equipment are coincident;
2) the back rest adopts an integral steel back and directly leans against the duct piece 2, and the back rest is required to be perpendicular to the axis of the pile when being placed;
3) the installation of the jack and the guide rail ensures that the center position of the jack is superposed with the axis of the pile, and also ensures that the elevation meets the design requirement;
4) the guide rail and the jack support must be firmly reinforced, so that pile pressing deviation caused by the influence on the transmission of pressure due to displacement in the pile pressing process is prevented;
thirdly, opening a tunnel bottom pipe piece 2, pressing the pipe pile into the soil, and positioning a spiral drill rod 4: before the auger stem 4 drills, all equipment is comprehensively checked, including whether a hydraulic, electric, grouting, lighting, communication, motor, oil pump and pipeline operation system can work normally or not, whether various electric meters, pressure meters and reversing valves display the working states of the electric meters and the pressure meters correctly or not, whether the installation positions of the equipment are accurate or not is carefully checked at the same time, linkage debugging is carried out, and after the condition that no fault exists is confirmed, drilling soil taking and pile pressing construction can be started after a person in charge checks and signs the fault;
before the auger stem 4 drills, the drilling deviation is strictly controlled, and the deviation of the central axis is not more than 10 mm;
step four, operating the spiral drill rod 4 to take soil, and simultaneously pressing the tubular pile: the spiral drill rod 4 presses the tubular pile downwards through the jack while drilling and taking soil, so that synchronous sinking of the spiral drill rod and the tubular pile is guaranteed;
in the initial stage of drilling the spiral drill rod 4, the deviation rectifying oil cylinders are used as few as possible, so that the accuracy of the tubular pile in height and left and right is kept;
when piping, collapsed soil and a large amount of water are gushed, precipitation and grouting reinforcement measures are adopted, and drilling is continued after treatment is finished;
in the whole process of drilling and pressing down, the measurement work is strengthened, the direction and height of errors are corrected by adopting different soil excavation amounts and deviation correcting oil cylinders, the principle of 'measuring and correcting on duty' is adhered to, the deviation correcting angle is kept at 10 '-20' and is not more than 1 degree, the deviation correction is carried out step by step, and the principle of 'slow correction and slow correction' is adhered to;
adjusting pile pressing speed at any time according to pressure change and deviation conditions in the pile pressing process, wherein the speed is controlled to be 50mm/min and not more than 70mm/min at most;
the pile pressing equipment can also select top pressing type pile sinking equipment or holding type pile sinking equipment besides a jack, the type and the balance weight of the pile pressing machine are selected according to design requirements and investigation reports or pile testing data, the pile sinking site of the static pressure method meets the requirements of the grounding pressure of the pile pressing machine, and various conditions in the pile sinking process are recorded in the pile pressing process, including pile pressing time, pile position numbers, pile body quality, soil penetration depth and corresponding pressure readings;
the pile sinking process meets the following requirements:
1) the verticality deviation of the pile is not more than 0.5%;
2) when the pile is pressed, the pile pressing machine is kept horizontal, and the holding pressure is not more than 1.1 times of the allowed lateral pressure of the pile body;
3) continuously sinking the pile to the designed elevation at one time, shortening the intermediate pause time as much as possible and avoiding pile splicing when approaching a bearing stratum;
in the static pressure method construction process, the control quality of the final pressure standard condition is determined according to the experimental result of the on-site pile test, and the preset final pressure standard can take a single pile bearing capacity characteristic value of 1.5-1.8;
fifthly, placing the next section of tubular pile and the spiral drill rod 4: after the pressure stroke of each section of tubular pile is finished and the jack is retracted, the next section of tubular pile can be installed, the spiral drill rod 4 is rigidly connected with each section of tubular pile, and the transmission of the force of the spiral drill rod 4 and the tubular pile is ensured;
before each section of tubular pile and the spiral drill rod 4 are installed, firstly, quality inspection is carried out, installation can be carried out after the quality inspection is confirmed, when the tubular pile is aligned with the opening, the tubular pile is hung on a track and is stable, the spigot end of the tubular pile is aligned with the socket end of the front pipe, the pipe is slowly pressed in, then the tubular pile is connected in a welding rigid connection mode, drilling soil is carried out, temporary stacking is needed on the site, the distance from the pile edge is at least not less than 3m when stacking is carried out, the soil piling height cannot be more than 2m, the soil is timely transported away, and excessive soil piling cannot be needed;
in the pipe pressing process, corresponding monitoring and protection measures are taken for underground buildings such as water, gas pipes, cables and the like within the range of 10m on the periphery;
the welding pile shall meet the following regulations besides the regulations of the secondary welding seam in the current national standard:
1) the pile head of the pile section of the soil entering part is higher than the bottom of the pipe piece 2 by 1.0 m;
2) the pile head of the lower pile is provided with a guide hoop or other guide measures, the upper pile section and the lower pile section are kept straight and staggered by no more than 2mm during pile splicing, and the bending rise of a node is not more than 1/1000 pile length and not more than 20mm during pile splicing section by section;
3) the bevels of the upper pile joint end plate and the lower pile joint end plate are clean and dry, and the welding part is brushed until the metallic luster is exposed;
4) when manual welding is carried out, firstly, 4-6 points are symmetrically spot-welded on the periphery of the groove, after the upper pile section and the lower pile section are fixed, the guide hoop is removed, and then layered welding is carried out, wherein the welding is carried out symmetrically;
5) the number of welding layers is not less than 2, the outer layer can be welded after the inner layer welding slag is cleaned up, and the welding seam is full and continuous;
6) when in manual electric arc welding, the first layer is preferably welded by a welding rod with the diameter of 3.2mm to ensure the root penetration, and the second layer can be a thick welding rod, preferably an E43 type series welding rod; when carbon dioxide gas is adopted for shielded welding, the welding wire is preferably ER50-6 type;
7) after the pile joint is welded, appearance inspection is carried out, pile sinking can be continued after the inspection is qualified, and watering and cooling are strictly forbidden;
8) welding the steel pile tip or the concrete pile tip in a factory; when welding is carried out on a construction site, welding is carried out on a stacking site, and the methods of spot welding and overhead welding after pile hoisting are strictly forbidden;
when the precast pile adopts a mechanical connection mode, the operation requirement of the corresponding mechanical connection mode is required to be met;
the precast pile cutting adopts a special pile sawing machine, and a large hammer is strictly forbidden to transversely knock and cut the pile or forcibly pull and pull the pile;
sixthly, the pile and the shield tunnel 1 are cast in place into a whole: the back is withdrawed to 4 sections of auger stem, finally is in the same place tubular pile and tunnel section of jurisdiction 2 cast in situ for the tubular pile links into a whole with shield tunnel 1, finally realizes the effective transmission of subway operation period load, also can make the tubular pile into the drilling bored concrete pile, can pour into the concrete in succession along with auger stem 4 proposes promptly, and the steel reinforcement cage is inserted in the subsection again.
Claims (1)
1. A control method for preventing a subway shield tunnel from long-term settlement is characterized by comprising the following steps: the method comprises the following steps:
constructing in a shield tunnel, enabling an outer sleeve and an auger stem in the outer sleeve to relatively rotate to drill holes at the bottom of a duct piece through a middle digging method, driving the auger stem to carry out spiral drilling by one power head, driving the outer sleeve to sink by the other power head, synchronously following the auger stem to descend, jacking the outer sleeve into a soil body below the duct piece one by utilizing a hydraulic jacking workstation or a jacking pile sinking or holding type pile sinking device in the shield tunnel, and continuously discharging the soil body in a pile pressing range into the shield tunnel through rotary drilling of the auger stem in the outer sleeve, so that the outer sleeve and the auger stem sink synchronously;
the outer sleeve is of a pipe pile structure and is a prefabricated prestressed concrete pipe pile or a steel sleeve prefabricated on site, the outer sleeve needs to be put down section by section, the length of each section of the outer sleeve is 1-3m, and the diameter of each section of the outer sleeve is 0.5-1 m;
the spiral drill rod is also assembled and drilled in sections like the outer sleeve, the length of each section of the spiral drill rod is consistent with that of the outer sleeve, and the diameter of each section of the spiral drill rod is smaller than the inner diameter of the outer sleeve;
the specific method comprises the following steps:
first step, early preparation: before engineering construction, determining a construction process according to a geological survey report, performing supplementary survey if necessary, performing geological survey within 5m of each of two sides of an axis of a pipe pile, checking whether the geology is consistent with the design, and checking whether existing buildings or pipelines exist nearby, if the geology is inconsistent with the design or has bad geology, enlarging the survey range, contacting with a design unit, and taking treatment measures;
secondly, measuring, positioning and equipment installation: according to known control points and elevations, accurately measuring and placing the position elevation and the axis of the positioning tubular pile, and according to the installation position of the measuring and placing equipment, a guide rail, a jack support, a backrest and a spiral drilling machine must be accurately and firmly arranged to ensure that subsequent construction is smoothly carried out, the equipment needs to be trial run before formal construction, formal construction can be carried out after performance requirements are met, and the following points are mainly paid attention to:
1) the pile pressing equipment and the soil sampling equipment are installed to ensure that the axes of the pile pressing equipment and the soil sampling equipment are overlapped;
2) the back rest adopts an integral steel back and directly leans against the pipe sheet, and the back rest is required to be perpendicular to the axis of the pipe pile when being placed;
3) the installation of the jack and the guide rail ensures that the center position of the jack is superposed with the axis of the tubular pile, and also ensures that the elevation meets the design requirement;
4) the guide rail and the jack support must be firmly reinforced, so that pile pressing deviation caused by the influence on the transmission of pressure due to displacement in the pile pressing process is prevented;
thirdly, opening a duct piece at the bottom of the tunnel, pressing the duct piece into the soil, and positioning the spiral drill rod: before the auger stem drills, all equipment is comprehensively checked, including whether a hydraulic system, an electric system, a mud jacking system, an illumination system, a communication system, a motor system, an oil pump system and a pipeline operation system can work normally or not, whether various electric meters, pressure meters and reversing valves display the working states of the electric meters and the pressure meters correctly or not is judged, whether the equipment installation positions are accurate or not is carefully checked at the same time, linkage debugging is carried out, and after the situation that no fault exists is confirmed, drilling soil taking and pile pressing construction can be started after a person in charge checks and signs the intention; before the auger stem drills, the drilling deviation is strictly controlled, and the deviation of the central axis is not more than 10 mm;
step four, operating the spiral drill rod to take out soil and simultaneously pressing the tubular pile: when the auger stem drills and fetches earth, the tubular pile is pressed down through the jack, and synchronous sinking of the auger stem and the tubular pile is guaranteed;
in the initial stage of drilling of the spiral drill rod, a deviation rectifying oil cylinder is used as little as possible, so that the accuracy of the height and the left and right of the tubular pile is kept;
when piping, collapsed soil and a large amount of water are gushed, precipitation and grouting reinforcement measures are adopted, and drilling is continued after treatment is finished;
in the whole process of drilling and pressing down, the measurement work is strengthened, the direction and height of errors are corrected by adopting different soil excavation amounts and deviation correcting oil cylinders, the principle of 'measuring and correcting on duty' is adhered to, the deviation correcting angle is kept at 10 '-20' and is not more than 1 degree, the deviation correction is carried out step by step, and the principle of 'slow correction and slow correction' is adhered to;
adjusting pile pressing speed at any time according to pressure change and deviation conditions in the pile pressing process, wherein the speed is controlled to be 50mm/min and not more than 70mm/min at most;
pile pressing equipment can select jacking pile sinking or holding pile sinking equipment besides a jack, the type and the balance weight of the pile pressing equipment are selected according to design requirements and investigation reports or pile testing data, a pile sinking site adopting a static pressure method meets the requirement of the ground pressure of the pile pressing equipment, and various conditions in the pile pressing process are recorded, including pile pressing time, pile position numbers, pile body quality, soil penetration depth and corresponding pressure readings;
the pile sinking process meets the following requirements:
1) the verticality deviation of the tubular pile is not more than 0.5%;
2) pile pressing equipment is kept horizontal during pile pressing, and the holding pressure is not more than 1.1 times of the allowable lateral pressure of a tubular pile body;
3) continuously sinking the tubular pile to the designed elevation at one time, shortening the intermediate pause time as much as possible and avoiding pile splicing when approaching a bearing stratum; in the static pressure method construction process, the control quality of the final pressure standard condition is determined according to the experimental result of the on-site pile test, and the characteristic value of the bearing capacity of a single pile is taken as 1.5-1.8 according to the preset final pressure standard;
fifthly, placing the next section of tubular pile and the spiral drill rod: after the pressure stroke of each section of tubular pile is finished and the jack is retracted, the next section of tubular pile can be installed, the auger stem and each section of tubular pile are rigidly connected, and the force transmission of the auger stem and the tubular pile is ensured;
before each section of tubular pile and the spiral drill rod are installed, firstly, quality inspection is carried out, the tubular pile can be installed after the tubular pile and the spiral drill rod are qualified, when the tubular pile are aligned, a pipe section is hung on a rail and is stable, the spigot end of the pipe section is aligned to the socket end of a front pipe, the pipe section is slowly pressed in, then the tubular pile is connected in a welding rigid connection mode, drilling and soil removal need to be temporarily stacked on the site, the distance from the edge of the tubular pile is at least not less than 3m during stacking, the soil stacking height cannot be more than 2m, the soil is timely transported away, and excessive soil stacking is avoided; in the pile pressing process, corresponding monitoring and protection measures are taken for underground buildings within 10m of the periphery; the welding pile shall meet the following regulations besides the regulations of the secondary welding seam in the current national standard:
1) the pile head of the pipe pile section of the soil entering part is 1.0m higher than the bottom of the pipe piece;
2) the pile head of the lower section of tubular pile is provided with a guide hoop or other guide measures, when pile splicing is carried out, the pile sections of the upper and lower sections of tubular pile are kept straight, the dislocation is not more than 2mm, and when the pile is spliced section by section, the bending rise of the node is not more than 1/1000 pile length and not more than 20 mm;
3) the bevel of the end plate of the upper and lower section pipe pile joints is clean and dry, and the welding part is brushed until the metal luster is exposed;
4) when manual welding is carried out, firstly, symmetrically spot-welding 4-6 points on the periphery of the groove, removing the guide hoop after the upper and lower section pipe piles are fixed, then carrying out layered welding, and carrying out symmetrical welding;
5) the number of welding layers is not less than 2, the outer layer can be welded after the inner layer welding slag is cleaned up, and the welding seam is full and continuous;
6) when in manual electric arc welding, the first layer is welded by a welding rod with the diameter of 3.2mm to ensure the root penetration, and the second layer is made of a thick welding rod by adopting an E43 type series welding rod; when carbon dioxide gas shielded welding is adopted, the welding wire is ER50-6 type;
7) after the pipe pile joint is welded, appearance inspection is carried out, pile sinking can be continued after the inspection is qualified, and watering and cooling are strictly forbidden;
8) welding the steel pile tip or the concrete pile tip in a factory; when welding is carried out on a construction site, welding is carried out on a stacking site, and the methods of spot welding and overhead welding after pile hoisting are strictly forbidden; when the precast pile adopts a mechanical connection mode, the operation requirement of the corresponding mechanical connection mode is required to be met; the precast pile cutting adopts a special pile sawing machine, and a large hammer is strictly forbidden to transversely knock and cut the pile or forcibly pull and pull the pile;
sixthly, the tubular pile and the shield tunnel are cast in situ as a whole: after the auger stem is withdrawn one section by one section, the tubular pile and the tunnel segment are cast in situ together finally, so that the tubular pile and the shield tunnel are connected into a whole, the tubular pile is arranged every 100-500 m along the longitudinal direction of the subway tunnel, and the effective transmission of the load in the subway operation period is realized finally.
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