CN117605481A - Micro-deformation control method for ultra-small clear distance of large-section subway tunnel to span existing tunnel - Google Patents
Micro-deformation control method for ultra-small clear distance of large-section subway tunnel to span existing tunnel Download PDFInfo
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- 238000005520 cutting process Methods 0.000 claims abstract description 47
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention provides a micro-deformation control method for a large-section subway tunnel to span an existing tunnel in an ultra-small clear distance, which belongs to the technical field of tunnels and underground engineering and comprises the steps of constructing left and right upper pilot holes at the design position of a newly-built underground tunnel, excavating a pipe-jacking working well, jacking the pipe, constructing manual hole-digging piles downwards at the left and right upper pilot holes of the newly-built underground tunnel, cutting the pipe-jacking when encountering the pipe-jacking, installing a reinforcement cage, pouring hole-digging pile concrete, pouring pipe-jacking inner cushion layers, installing profile steel and beam stirrups in the pipe-jacking, connecting the pipe-jacking with the reinforcement cage, installing an arc-shaped template identical to the overlapping part of the primary support of the newly-built underground tunnel, pouring pipe-jacking inner concrete, excavating left lower pilot holes and right lower pilot holes, and cutting and initially-supporting the pipe-jacking overlapping part. According to the invention, the upper tunnel and the lower tunnel are isolated through the special-shaped bench beam structure formed by the special-shaped top pipe beam and the pile body, the impact is born on the excavation and unloading of the newly-built tunnel, and the rebound deformation of the existing tunnel caused by the excavation of the newly-built tunnel is effectively resisted.
Description
Technical Field
The invention belongs to the technical field of tunnel and underground engineering construction, and particularly relates to a micro-deformation control method for a large-section subway tunnel to span an existing tunnel at an ultra-small clear distance.
Background
At present, the urban process of China is faster and faster, the construction of urban rail transit lines is continuously perfected, and the projects of newly built subways crossing existing tunnels are increasingly increased. The crossing clear distance between subway tunnels in cities is small, the mutual influence is large, and when the subway tunnels are constructed in a crossing way, the stress balance state of the original stratum can be broken, so that the structural deformation and floating of the existing tunnels are caused. When the clear distance between the newly-built large-section subway tunnel and the existing tunnel is small, the excavation of the newly-built tunnel can enable the existing tunnel to generate larger deformation, and even the existing subway tunnel can be caused to generate structural damage to influence the safety of trains in the existing tunnel. Under the complex condition, when a new large-section subway tunnel is constructed in an upward crossing way, the safety operation of the existing subway tunnel is ensured as a primary target.
At present, the deformation control measures of the existing tunnel often adopt a pre-grouting reinforcement mode, the bottom of the newly-built tunnel and soil surrounding the existing tunnel are pre-grouting reinforced, grouting materials with larger viscosity are filled into holes of stratum through grouting holes, the deformation resistance of the soil is improved, and the influence of the excavation of the overstretched tunnel on the existing tunnel is reduced. However, the conventional stratum pre-grouting reinforcement measures are difficult to control the deformation of the existing tunnel within an allowable range, so that a new deformation control method is required to be provided, the deformation of the existing tunnel in the midspan construction process is controlled within a reasonable range, and the structural safety of the existing tunnel and the normal operation of a subway train are ensured.
Disclosure of Invention
The invention aims to provide a micro-deformation control method for an existing tunnel with a large-section subway tunnel and a super-small clear distance, and aims to solve the technical problem that potential safety hazards are caused by floating deformation of the existing tunnel due to excavation of a newly-built underground tunnel.
In order to achieve the above purpose, the invention adopts the following technical scheme: the micro-deformation control method for the ultra-small clear distance of the large-section subway tunnel to span the existing tunnel comprises the following steps:
constructing an upper left pilot tunnel and an upper right pilot tunnel at the design position of a newly built undercut tunnel by adopting a CRD (China railway high-speed) construction method;
step two, excavating a pipe-jacking working well at one side of the existing tunnel, and excavating the pipe-jacking working well downwards at the bottom of the upper pilot tunnel of the newly-built undercut tunnel according to the design position of the starting point of the pipe jacking;
step three, after the pipe jacking working well is excavated, installing jacking equipment in the pipe jacking working well;
step four, jacking the jacking pipe, namely constructing two manual jacking pipes above the existing tunnel, adopting a manual soil digging mode, enabling operators to dig out soil layers in the jacking pipe range in advance, and jacking the jacking pipe;
step five, constructing a manual hole digging pile as an anti-pulling pile, digging downwards the manual hole digging pile at the bottom of an upper pilot tunnel in a newly built underground tunnel above two ends of a jacking pipe, and cutting the jacking pipe when encountering the jacking pipe along with supporting along with digging during digging;
step six, after the hole digging pile is excavated, placing a reinforcement cage in the pile, wherein the length of a main reinforcement in the reinforcement cage is 5 times larger than the diameter of a reinforcement with the design elevation of the section steel in the jacking pipe; the spiral stirrups are arranged on the outer side of the reinforcement cage and extend from the bottom of the jacking pipe to the bottom of the hole digging pile; the reinforcing stirrups are arranged on the inner side of the reinforcement cage according to the designed interval; then pouring concrete in the hole digging pile, wherein the concrete is poured from the bottom of the hole digging pile to a position above the designed elevation of the concrete cushion layer in the jacking pipe;
step seven, firstly constructing beam stirrups in the top pipe, and pouring plain concrete cushion layers after the beam stirrups are installed; after the plain concrete cushion layer reaches the design strength, chiseling the pile head concrete of the hole digging pile, starting to arrange the I-steel, welding the beam stirrup and the I-steel, paving the deformed bar on the upper part of the I-steel, and welding the deformed bar and the I-steel;
step eight, after the arrangement of the I-steel and the steel bars in the jacking pipe is completed, the hole digging pile is stretched into the jacking pipe, the main steel bar with the elevation higher than that of the I-steel is bent, then welded with the I-steel, an arc-shaped template is installed, one side of the jacking pipe is plugged, and concrete is poured in the jacking pipe;
step nine, excavating a left lower pilot tunnel and a right lower pilot tunnel of a newly-built underground tunnel by adopting a CRD construction method, wherein the overlapped part of the jacking pipe and the primary support is sequentially cut off along with the excavation of the tunnel, erecting a partition wall in the pilot tunnel at the lower part of the tunnel in time, and constructing the primary support;
cutting the jacking pipe to form an arc-shaped groove, defining a special-shaped jacking pipe beam, and combining the special-shaped jacking pipe beam with the hole digging pile to form a special-shaped bench beam structure.
In one possible implementation manner, when the pipe jacking construction is carried out, the construction steps are that beam stirrups are paved into a hollow pipe jacking, plain concrete cushion layers are poured, I-steel is paved on the plain concrete cushion layers, threaded steel bars are arranged on the I-steel, after the main steel bars of the steel reinforcement cage are welded with the I-steel, arc-shaped templates are installed, one side of the pipe jacking is blocked, and concrete is poured into the pipe jacking.
In one possible implementation, when concrete is poured into the hole-digging pile, the pouring is stopped when the concrete reaches the position above the height of the plain concrete cushion layer in the jacking pipe, after the concrete is solidified, the pile head concrete is broken and the main reinforcement of the steel reinforcement cage is exposed, and the main reinforcement is bent into the jacking pipe and welded with the I-steel.
In one possible implementation manner, the jacking device comprises a jack, a back rest, a guide rail bracket, a concrete buttress and a steel beam, wherein the hydraulic jack is used as jacking power, the back rest and the concrete buttress are fixedly arranged in the jacking pipe working well, one end of the jack is fixedly connected with the back rest, the other end of the jack is used for pushing a jacking pipe, the jacking pipe slides on the guide rail, the guide rail is fixedly connected with the guide rail bracket, the guide rail bracket is fixedly connected with the steel beam, and the steel beam is fixedly connected with the concrete buttress.
In one possible implementation manner, the jacking pipe jacking process sequentially comprises the following steps: the equipment debugging operation, pipe discharging, pipe jacking in place, soil digging before pipe jacking, pipe jacking correction and pipe jacking process recording and management.
In one possible implementation, the length of each pre-pipe digging and each jacking length is determined according to geological conditions, and is generally controlled within 0.5m until all jacking pipes are jacked.
In a possible implementation manner, in the fifth step, the manual hole digging pile is perpendicular to the jacking pipe, the pile diameter of the manual hole digging pile is smaller than the pipe diameter of the jacking pipe, and then the upper surface and the lower surface of the intersection part of the jacking pipe and the hole digging pile are cut.
In one possible implementation, the step of cutting the jacking pipe sequentially includes:
the cutting step of the upper surface of the jacking pipe is as follows: digging to the upper part of the jacking pipe, cleaning the cutting outline, applying artificial retaining wall, cleaning slag soil on the pipe wall, stacking sand bags at the cutting part inside the jacking pipe, plugging square timber above the sand bags, cutting in blocks, hanging out cut steel pipes, and withdrawing the square timber sand bags;
the lower surface cutting step of the jacking pipe is as follows: measuring and positioning the cutting profile, cleaning the slag soil on the pipe wall, cutting in blocks, and transporting out the cut steel pipe in the pipe jacking.
In one possible implementation, the construction steps of the manual hole digging pile sequentially include:
constructing a locking collar beam and a first section of hole digging pile retaining wall, setting out a pile position, breaking a temporary inverted arch part of the pile position, digging a first section of hole digging pile (depth is about 1 m), and constructing the locking collar beam and the first section of retaining wall, wherein a reinforced concrete structure is adopted for the hole collar and the retaining wall of the manual hole digging pile;
pile body excavation, namely excavating layer by layer from top to bottom, wherein the excavation depth of each section during construction is 1m, the center line of the pile should be corrected at any time in the excavation process, and if deviation is found, the correction should be carried out in time;
constructing an artificial retaining wall, wherein the artificial retaining wall adopts a reinforced concrete structure, and is constructed to the pile bottom section by section along with the excavation of a pile hole, and the construction is sequentially and circularly carried out;
and (3) cutting the top pipe at the crossing part of the manual hole digging pile during the construction of the manual hole digging pile, and welding the manual retaining wall vertical steel bar above the top pipe with the top pipe after the top pipe cutting is completed.
In one possible implementation mode, 3-4 barbs are welded at the bottom of a reinforcement cage in the manual hole digging pile, so that the barbs are inserted into the pile bottom to prevent the reinforcement cage from floating upwards when concrete is poured; before construction, groundwater is lowered to a position at least 1m below the designed pile bottom of the manual hole digging pile construction so as to ensure that soil in the pile hole is dry; the installation longitudinal gradient of the guide rail and the jack is consistent with the design gradient of the jacking pipe.
The micro-deformation control method for the large-section subway tunnel to span the existing tunnel at the ultra-small clear distance has the beneficial effects that: compared with the prior art, the micro-deformation control method for the large-section subway tunnel with the ultra-small clear distance and the existing tunnel is characterized by comprising the steps of constructing left and right upper pilot holes at the design position of a newly-built underground tunnel, excavating a pipe-jacking working well, jacking the pipe, constructing manual hole-digging piles downwards at the left and right upper pilot holes of the newly-built underground tunnel, cutting the pipe when encountering the pipe, installing a reinforcement cage, pouring concrete of the hole-digging piles, pouring an inner cushion layer of the pipe, installing section steel in the pipe and beam stirrups, connecting the pipe with the reinforcement cage, installing an arc-shaped template identical to the overlapping part of the primary support of the newly-built underground tunnel, pouring concrete in the pipe, excavating left lower pilot holes and right lower pilot holes, and cutting partial pipe overlapped with the primary support. The micro-deformation control method for the ultra-small clear distance of the large-section subway tunnel to span the existing tunnel solves the technical problem that the ultra-small clear distance of the newly-built underground tunnel spans the existing tunnel, the existing tunnel is floated and deformed to bring potential safety hazards due to the excavation of the underground tunnel, the upper tunnel and the lower tunnel are isolated through the special-shaped bench beam structure formed by the special-shaped top tube beam and the pile body, the influence caused by the excavation and unloading of the newly-built tunnel is borne, and the rebound deformation of the existing tunnel caused by the excavation of the newly-built tunnel is effectively resisted.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments or the description of the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a block diagram of steps of a micro-deformation control method for a large-section subway tunnel to span an existing tunnel at an ultra-small clear distance;
fig. 2 is a schematic diagram of a special-shaped bench beam constructed by a micro-deformation control method for crossing an existing tunnel at an ultra-small clear distance in a large-section subway tunnel according to an embodiment of the invention;
fig. 3 is a schematic structural diagram of jacking equipment constructed by a micro-deformation control method for crossing an existing tunnel on an ultra-small clear distance of a large-section subway tunnel provided by the embodiment of the invention;
FIG. 4 is a cross-sectional view of a jacking pipe and an upper pilot tunnel of a newly-built undercut tunnel of a micro-deformation control method for a large-section subway tunnel with ultra-small clear distance and an existing tunnel;
fig. 5 is a front view of a hole digging pile and a newly built undercut tunnel structure of a micro-deformation control method for a large-section subway tunnel with ultra-small clear distance and crossing an existing tunnel, provided by the embodiment of the invention;
fig. 6 is a section view of a special-shaped bench beam constructed by a micro-deformation control method for a large-section subway tunnel with ultra-small clear distance and an existing tunnel (when a lower pilot tunnel of a newly-built underground tunnel is not excavated after the construction of the special-shaped bench beam is completed);
FIG. 7 is a cross-sectional view of the profile bench beam and the newly-built undercut tunnel of FIG. 6 (after the excavation and support of the lower pilot tunnel of the newly-built undercut tunnel is completed);
fig. 8 is a schematic diagram of a positional relationship between a special-shaped bench beam and a tunnel constructed by a micro-deformation control method for a large-section subway tunnel with ultra-small clear distance and crossing an existing tunnel, provided by the embodiment of the invention;
FIG. 9 is a diagram of the internal structure of a special-shaped bench beam constructed by a micro-deformation control method for the ultra-small clear distance of a large-section subway tunnel and crossing an existing tunnel, provided by the embodiment of the invention;
FIG. 10 is a schematic view of the interior structure of the shaped roof beam of FIG. 9;
fig. 11 is a layout diagram of steel bars in a jacking pipe constructed by a micro-deformation control method for a large-section subway tunnel with ultra-small clear distance and crossing an existing tunnel, provided by the embodiment of the invention;
fig. 12 is a top view of a reinforcement cage structure constructed by a micro-deformation control method for a large-section subway tunnel with ultra-small clear distance and crossing an existing tunnel.
Reference numerals illustrate:
1. a pile body; 11. a reinforcement cage; 111. a main rib; 112. spiral stirrups; 113. reinforcing stirrups; 12. a first concrete; 13. a retaining wall structure; 2. a special-shaped top tube beam; 21. i-steel; 22. a second concrete; 23. a plain concrete cushion layer; 24. jacking pipes; 25. beam stirrups; 26. screw-thread steel bar; 3. an existing tunnel; 4. newly building a subsurface tunnel; 41. an upper pilot hole on the left side; 42. a left lower pilot hole; 43. an upper pilot hole on the right side; 44. a right lower pilot hole; 5. an arc-shaped groove; 6. jacking equipment; 61. a jack; 62. a back rest; 63. a guide rail; 64. a guide rail bracket; 65. a concrete buttress; 66. a steel cross beam; 7. an arc-shaped template; 8. and a cutting portion.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Referring to fig. 1 to 12, a micro-deformation control method for a large-section subway tunnel with ultra-small clear distance crossing an existing tunnel will be described. The micro-deformation control method for the ultra-small clear distance of the large-section subway tunnel to span the existing tunnel sequentially comprises the following steps of:
step one, constructing a left upper pilot tunnel 41 and a right upper pilot tunnel 43 at the design position of a newly built undercut tunnel 4 by adopting a CRD construction method;
step two, excavating a pipe jacking working well at one side of the existing tunnel 3, and excavating the pipe jacking working well downwards at the bottom of an upper pilot tunnel (comprising an upper pilot tunnel 41 at the left side and an upper pilot tunnel 43 at the right side) of the newly-built underground tunnel 4 according to the design position of the starting point of the pipe jacking;
step three, after the pipe jacking working well is excavated, installing jacking equipment 6 in the pipe jacking working well; as shown in fig. 3;
step four, jacking pipe (formed by welding a plurality of sections of steel pipes end to end), constructing two manual pipe jacking above the existing tunnel 3, adopting a manual soil digging mode, and enabling operators to excavate soil layers in the pipe jacking range in advance and then jacking the pipe jacking; as shown in fig. 4;
step five, constructing a manual hole digging pile as an anti-pulling pile, digging the manual hole digging pile downwards at the bottom of an upper pilot tunnel in a newly built underground tunnel 4 above two ends of a jacking pipe, and cutting the jacking pipe when encountering the jacking pipe along with supporting along with digging during digging; the cut-off portion is a cutting portion 8 as shown in fig. 5;
step six, after the excavation of the hole-digging pile (namely the pile body 1 in the application, namely the manual hole-digging pile) is completed, placing a steel reinforcement cage 11 in the pile hole, wherein the length of a main reinforcement 111 in the steel reinforcement cage 11 is higher than the diameter of a steel reinforcement with the design elevation of 5 times of that of the section steel (namely the I-steel 21) in the jacking pipe; arranging spiral stirrups 112 on the reinforcement cage 11 from the bottom of the jacking pipe to the bottom of the hole digging pile; then pouring the concrete in the hole digging pile (namely the first concrete 12 in the application), and pouring the concrete in the hole digging pile from the bottom of the hole digging pile to the position above the designed elevation of the plain concrete cushion layer 23 in the jacking pipe;
step seven, firstly constructing beam stirrups 25 in the top pipe 24, and pouring plain concrete cushion layers 23 after the beam stirrups 25 are installed; after the plain concrete cushion layer 23 reaches the design strength, breaking the pile head concrete of the hole digging pile, starting to arrange the I-steel 21, and welding the beam stirrup 25 and the I-steel 21; then, paving a deformed bar 26 on the upper part of the I-steel 21, and welding the deformed bar 26 and the I-steel 21; as shown in fig. 11;
step eight, after the arrangement of the I-steel 21 and the deformed steel bars 26 in the jacking pipe is completed, the hole digging pile is stretched into the main rib 111 which is higher than the elevation of the I-steel 21 in the jacking pipe beam, and is welded with the I-steel 21, then an arc-shaped template 7 is installed to seal one side of the jacking pipe, and a second concrete 22 is poured in the jacking pipe;
step nine, excavating a left lower pilot tunnel 42 and a right lower pilot tunnel 44 of the newly-built underground tunnel by adopting a CRD construction method, wherein the overlapped part of the jacking pipe and the primary support is sequentially cut along with the excavation of the tunnel, the partition wall in the lower pilot tunnel of the tunnel is erected in time, and the primary support is constructed, as shown in fig. 7; cutting the jacking pipe 24 to form an arc-shaped groove 5, defining a special-shaped jacking pipe beam 2, and combining the special-shaped jacking pipe beam 2 with the pile body 1 to form a special-shaped bench beam structure.
The micro-deformation control method for the large-section subway tunnel to span the existing tunnel at the ultra-small clear distance has the beneficial effects that: compared with the prior art, the micro-deformation control method for the large-section subway tunnel with the ultra-small clear distance and the upper span of the existing tunnel comprises the steps of constructing an upper left pilot tunnel 41 and an upper right pilot tunnel 43 at the design position of a newly-built underground tunnel, excavating a top pipe working well, jacking a top pipe 24, constructing manual hole digging piles downwards at the upper left side and the right side of the newly-built underground tunnel, cutting the top pipe when encountering the top pipe, installing a reinforcement cage 11, pouring hole digging pile concrete (first concrete 12), paving beam stirrups 25, pouring a top pipe inner cushion layer (plain concrete cushion layer 23), installing top pipe inner section steel (I-shaped steel 21) and a threaded steel 26, connecting the top pipe (I-shaped steel 21) with the reinforcement cage 11, installing an arc-shaped template 7 which is identical to the overlapping part of the initial support of the newly-built underground tunnel, pouring top pipe inner concrete (second concrete 22) and excavating a lower left side pilot tunnel 42 and a lower right side pilot tunnel 44, and cutting the part overlapping with the initial support. The micro-deformation control method for the ultra-small clear distance of the large-section subway tunnel to span the existing tunnel solves the technical problem that the ultra-small clear distance of the newly-built underground tunnel 4 spans the existing tunnel 3, the existing tunnel 3 floats upwards and deforms to bring potential safety hazards due to the excavation of the underground tunnel, the upper tunnel and the lower tunnel are isolated through the special-shaped bench beam structure formed by the special-shaped top tube beam 2 and the pile body 1, the influence caused by the excavation and unloading of the newly-built tunnel is borne, and the rebound deformation of the existing tunnel 3 caused by the excavation of the newly-built tunnel is effectively resisted.
The special-shaped bench beam structure comprises a plurality of pile bodies 1 and a special-shaped top pipe beam 2, wherein a part of the upper end of the top pipe is cut to form an arc-shaped groove 5, the pile bodies 1 are respectively arranged on two sides of an existing tunnel 3 and are vertically arranged, and pile ends are embedded into a ground layer; the special-shaped top pipe beam 2 is fixedly connected to pile tops of the pile bodies 1, the special-shaped top pipe beam 2 is horizontally arranged, and two ends of the special-shaped top pipe beam 2 are respectively positioned at two sides of the existing tunnel 3; wherein, a plurality of pile bodies 1 and special-shaped top tubular beams 2 are combined to form a special-shaped bench beam structure and ride over the existing tunnel 3 to form a roof pressing structure for the existing tunnel 3, and the special-shaped bench beam structure is positioned below the newly-built undercut tunnel 4.
The special-shaped bench beams formed by combining the plurality of pile bodies 1 with the special-shaped top pipe beams 2 can realize load transfer by riding over the existing tunnel 3, ensure the structural safety of the existing tunnel 3, are suitable for the condition of ultra-small clear distance, solve the technical problem that the existing tunnel 3 floats upwards and deforms to bring potential safety hazards due to the fact that the existing tunnel 4 is erected on the ultra-small clear distance, separate the upper tunnel from the lower tunnel (refer to the existing tunnel 3 and the new existing tunnel 4) through the special-shaped bench beam structure formed by the special-shaped top pipe beams 2 and the pile bodies 1, bear the influence of unloading of the new tunnel excavation, and can effectively resist rebound deformation of the existing tunnel 3 caused by the new tunnel excavation.
The special-shaped top pipe beam 2 is a top pipe beam 2 formed after an arc-shaped template 7, second concrete 22 and the like are placed on an arc-shaped groove 5 of a top pipe 24 and an overlapping part of the special-shaped top pipe beam 2 and an initial support is cut in the construction process of a pilot tunnel under a newly-built undercut tunnel 4.
The ultra-small clear distance tunnel refers to a tunnel arrangement mode that the soil thickness between an upper tunnel and a lower tunnel is smaller than a certain value. Along with the development of highway, railway and urban rail transit construction, the minimum clear distance between the upper tunnel and the lower tunnel is smaller than a certain value when the lines are crossed due to the limitation of conditions during line selection, and the structural safety of the existing tunnels is greatly adversely affected. Therefore, measures such as the control method of the present invention are taken.
In this embodiment, if the existing tunnel 3 is provided as one, one pile body 1 is respectively provided at two sides of the existing tunnel 3, and the profiled roof beam 2 spans over the existing tunnel 3 and is connected with the pile body 1. If the existing tunnels 3 are two (bidirectional tunnels) arranged in parallel, at least three piles 1 are arranged, namely, as shown in fig. 2, three piles 1 are arranged in parallel, the middle pile 1 is positioned between the two existing tunnels 3, and the special-shaped top pipe beams 2 are fixedly connected to the upper ends of the three piles 1, so that a structure similar to a stool is formed by combining, and the special-shaped stool beams are considered. The diameter of the special-shaped top tube beam 2 is larger than the outer diameter of the pile body 1.
In some embodiments, referring to fig. 1 to 10, the jacking device 6 includes a jack 61, a back rest 62, a guide rail 63, a guide rail bracket 64, a concrete buttress 65 and a steel beam 66, hydraulic jacks are adopted as jacking power, the back rest 52 and the concrete buttress 54 are fixedly arranged in the jacking pipe working well, one end of the jack 61 is fixedly connected with the back rest 62, the other end of the jack is used for jacking a jacking pipe, the jacking pipe slides on the guide rail 63, the guide rail 63 is fixedly connected with the guide rail bracket 64, the guide rail bracket 64 is fixedly connected with the steel beam 66, and the steel beam 66 is fixedly connected with the concrete buttress 65.
In some embodiments, referring to fig. 1 to 12, the jacking process sequentially includes the following steps: the equipment debugging operation, pipe discharging, pipe jacking in place, soil digging before pipe jacking, pipe jacking correction and pipe jacking process recording and management. The length of each soil digging before pipe and each jacking length is determined according to geological conditions, and is generally controlled within 0.5m until all jacking pipes are jacked.
In some embodiments, referring to fig. 1 to 12, in the fifth step, the manual hole digging pile is perpendicular to the top pipe 24, the pile diameter of the manual hole digging pile is smaller than the pipe diameter of the top pipe 24, and the upper surface and the lower surface of the intersecting part with the top pipe are cut in the pile hole digging construction.
In some embodiments, referring to fig. 1 to 12, the step of cutting the jacking pipe sequentially includes:
the cutting step of the upper surface of the jacking pipe is as follows: digging to the upper part of the jacking pipe, cleaning the cutting outline, applying artificial retaining wall, cleaning slag soil on the pipe wall, stacking sand bags at the cutting part inside the jacking pipe, plugging square timber above the sand bags, cutting in blocks, hanging out cut steel pipes, and withdrawing the square timber sand bags;
the lower surface cutting step of the jacking pipe is as follows: measuring and positioning the cutting profile, cleaning the slag soil on the pipe wall, cutting in blocks, and transporting out the cut steel pipe in the pipe jacking.
The block cutting is to cut the upper end and the lower end of the jacking pipe into blocks successively, wherein the cutting process comprises plasma cutting, laser cutting, water cutting and the like, and a proper operation process is selected during operation according to actual conditions.
In some embodiments, referring to fig. 1 to 12, the construction steps of the manual hole digging pile sequentially include:
constructing a locking collar beam and a first section of hole digging pile retaining wall, setting out a pile position, breaking a temporary inverted arch part of the pile position, digging the first section of hole digging pile, and constructing the locking collar beam and the first section of retaining wall, wherein the manual hole digging pile hole collar and the retaining wall adopt reinforced concrete structures;
pile body excavation, namely excavating layer by layer from top to bottom, wherein the excavation depth of each section during construction is 1m, the center line of the pile should be corrected at any time in the excavation process, and if deviation is found, the correction should be carried out in time;
constructing the artificial retaining wall, wherein the artificial retaining wall adopts a reinforced concrete structure, and the construction is carried out on the pile bottom section by section along with the excavation of the pile hole, and the construction is carried out in sequence and circularly;
and (3) cutting the top pipe at the crossing part of the manual hole digging pile during the construction of the manual hole digging pile, and welding the manual retaining wall vertical steel bar above the top pipe with the top pipe after the top pipe cutting is completed.
In some embodiments, referring to fig. 1 to 12, 3-4 barbs are welded to the bottom of a reinforcement cage in a manual hole digging pile, so that the barbs are inserted into the pile bottom to prevent the reinforcement cage from floating upward when concrete is poured. Before construction, the underground water level is reduced to a position at least 1m below the pile bottom of the manual hole digging pile construction design so as to ensure the dryness of soil in the pile hole. The installation longitudinal gradient of the guide rail and the jack is consistent with the design gradient of the jacking pipe.
The special-shaped top pipe beam 2 and the pile body 1 connected with the special-shaped top pipe beam are combined to form a group of bench beam structures, and a plurality of groups of bench beam structures are arranged along the existing tunnel 3. Pile body 1 has played the effect to the support of dysmorphism top tubular beam 2, and pile body 1 tip firmly imbeds in the stratum, for furthest's the come-up deformation of avoiding existing tunnel 3, can set up multiunit dysmorphism bench roof beam structure along the length direction of existing tunnel 3, can equidistant setting, also can be close to each other and set up, need rationally set up according to actual conditions etc. in stratum, can guarantee the safe construction of newly-built undercut tunnel 4 and the normal operation of existing tunnel 3 like this.
In some embodiments, referring to fig. 1 to 12, the newly built tunnel 4 is constructed by CRD, the interior of the newly built tunnel 4 is divided into a left upper pilot hole 41, a left lower pilot hole 42, a right upper pilot hole 43 and a right lower pilot hole 44, which are arranged corresponding to the four areas separated by the newly built tunnel in fig. 6, and the construction method is not described in detail herein. The special-shaped top tube beams 2 are respectively arranged right below the left lower pilot tunnel 42 and the right lower pilot tunnel 44 of the newly-built undercut tunnel 4, the pile bodies 1 are respectively correspondingly connected with the two special-shaped top tube beams 2, and the axial direction of the special-shaped top tube beams 2 is parallel to the length direction of the newly-built undercut tunnel 4. The position of the special-shaped top tube beam 2 in the embodiment can ensure the structural safety of the existing tunnel 3 to the maximum extent, and the effect is good. The solid line in fig. 6 shows the positions of the two piles 1 correspondingly arranged, and the special-shaped top pipe beam 2 is axially arranged perpendicular to the existing tunnel 3.
In some embodiments, referring to fig. 1 to 12, the pile body 1 includes a reinforcement cage 11 and a poured first concrete 12, and the profiled top pipe beam 2 includes a beam stirrup 25, an i-beam 21 connected to the beam stirrup 25, a rebar 26 laid on top of the i-beam 21, and a second concrete 22 poured in the profiled top pipe 24. The use of the i-steel 21 and the deformed bar 26 can enhance the structural rigidity of the top tubular beam, and the first concrete 12 is bonded and combined with the reinforcement cage 11 to form a whole, namely the pile body 1 after solidification. The second concrete 22 is solidified and then combined with the special-shaped top pipe 24, the beam stirrup 25, the I-steel 21, the thread rib 26 and the like to form a whole, namely the special-shaped top pipe beam 2. A plain concrete cushion layer 23 is arranged in the special-shaped top pipe beam 2 and is positioned below the I-steel 21.
To achieve the fixed connection between the shaped top tubular beam 2 and the pile body 1, in some embodiments, referring to fig. 1 to 10, the i-steel 21 is welded to the main rib 111 at the upper end of the reinforcement cage 11 to fix the shaped top tubular beam 2 and the pile body 1. The special-shaped top tube beam 2 and the pile body 1 can be permanently and fixedly connected to form a whole in a welding connection mode, and the stability of the whole structure can be improved.
In some embodiments, referring to fig. 1 to 12, the reinforcement cage 11 is a structure formed by combining a plurality of main ribs 111, a plurality of spiral stirrups 112 and a plurality of reinforcing stirrups 113, wherein the plurality of main ribs 111 are vertically arranged and combined to form a circle, the spiral stirrups 112 are wrapped around the outer sides of the plurality of circular main ribs 111 and are welded or bound with the plurality of main ribs 111, and the reinforcing stirrups 113 are arranged on the inner sides and are welded or bound with the plurality of main ribs 111. The pile body 1 is a uplift pile, during welding operation, concrete at the upper end of the pile body 1 is broken, a main rib 111 (reinforcing steel bars) extending out of the upper end of a reinforcement cage 11 is peeled off and then bent, and is anchored into the special-shaped top tube beam 2, and then welding is performed.
In some embodiments, referring to fig. 1 to 12, the length direction of the i-steel 21 is parallel to the axial direction of the special-shaped top tube beam 2, the i-steel 21 is a plurality of i-steels and is parallel to each other and arranged at equal intervals, and the i-steel 21 is located at a position below the middle of the inner side of the special-shaped top tube beam 2.
In some embodiments, referring to fig. 1 to 12, the pile body 1 is provided with a retaining wall structure 13.
The retaining wall structure 13 is that the soil layer below the earth surface receives the action of soil pressure in the excavation process of manual hole digging pile, often can cause the condition that the soil body collapses to take place, in order to ensure the safety and the quality of hole digging pile construction, generally need take the retaining wall measure to the pore wall, especially under the comparatively complicated circumstances of geological conditions, should combine structural strength and economic cost, adopt the retaining wall structure 13 of different forms to the soil layer of different circumstances, the retaining wall structure 13 that often adopts in the construction has: brick retaining wall, cast-in-place concrete retaining wall, steel sleeve retaining wall, jet rapid hardening concrete retaining wall, corrugated steel form tool type retaining wall and the like, and in special cases, retaining wall is adopted for the pile end enlarged head part, such as combined steel plate concrete retaining wall. The various retaining wall types have advantages, disadvantages and application ranges, and proper retaining wall structures are selected according to specific engineering geology and hydrogeology conditions of a site on the premise of ensuring the safety of constructors by comprehensively considering factors such as construction period, economy and the like.
In some embodiments, referring to fig. 1 to 12, the pile body 1 is an artificial hole pile. The manual hole digging pile is a reinforced concrete pile which adopts a manual hole digging mode and is cast in situ, and the setting mode or the construction method can be seen in the prior art.
The part of the manual hole digging pile above the special-shaped top pipe beam 2 is an empty pile, the first concrete 11 is not poured, and redundant manual protection walls are broken when a pilot tunnel is dug under a newly built tunnel as shown in fig. 9.
The diameters, the lengths and the number of the special-shaped top tube beams 2 and the manual hole digging piles below the newly-built tunnel are set according to actual engineering requirements; the clearance between the manual hole digging pile and the existing tunnel 3 is not too small, so that adverse effects on the existing tunnel 3 are prevented when the hole digging pile is implemented.
The invention provides a deformation control measure for the ultra-small clear distance of the newly-built undercut tunnel 4 to span the existing tunnel 3, and has at least the following advantages and effects:
in the construction process, the invention has high construction speed and high efficiency, can form standardized operation, and the manual hole digging pile can be constructed in the underground tunnel without being influenced by external conditions; the construction of the special-shaped top tube beam 2 is carried out in a working well, so that the influence on ground traffic is small.
According to the invention, the upper tunnel and the lower tunnel are isolated through the special-shaped bench beam structure formed by the special-shaped top pipe beam 2 and the hole digging pile, the influence caused by the unloading of the newly-built tunnel excavation is borne, and the rebound deformation of the existing tunnel 3 caused by the newly-built tunnel excavation can be effectively resisted.
The special-shaped bench beam structure is integrally ridden over the existing tunnel 3 to serve as a permanent protection structure of the special-shaped bench beam structure, so that the safety risk of the later-period subway operation dynamic load on the existing tunnel 3 structure can be reduced.
Specific applications of the invention are illustrated:
taking the line 17 second-phase engineering of the rail transit in the city of adulthood as an example, the line 17 second-phase engineering of the rail transit in the city of adulthood starts from the machine-put bridge station and reaches the Gao Hongcun station. The lines are generally in the direction from southwest to northeast and have the total length of about 24.8km, are all underground lines, and are provided with 18 underground stations, wherein 12 transfer stations. The maximum inter-site distance is 2757m, the minimum inter-site distance is 582m, and the average inter-site distance is 1356m.
The Yang Gongqiao station-dragon claw weir station interval is positioned at the west side of the intersection of Jin Yanglu and the middle loop, is laid along the east-west of the Jinyang road, starts from the south side of the Dragon viaduct and ends at the small mileage end shield receiving well of the dragon claw weir station; the designed mileage range is as follows: left line zdk78+903 to zdk79+890.771, section left line length 987.771m, right line ydk78+903 to ydk79+892.405, right line length 989.405m.
The upper span section of the newly built track traffic No. 17 line is similar to a left line and a right line which orthogonally pass through the existing No. 7 line section, the upper span length is about 45m, and the minimum clear distance between the two structures is about 1.21m. The special-shaped bench beam measures are adopted to protect the existing No. 7 tunnel, and the special-shaped bench beam comprises the following concrete implementation steps:
firstly, a CRD construction method is adopted for newly-built tunnels, and left and right pilot tunnels at the upper part of the tunnels are firstly excavated;
secondly, excavating a pipe jacking working well, namely excavating the working well downwards at the bottom of a pilot tunnel at the upper part of the newly-built undercut tunnel 4 according to the design position of the starting point of the pipe jacking;
and thirdly, installing jacking equipment 6, namely installing a jacking jack 61, a back rest 62, a guide rail 63, a guide rail bracket 64, a concrete buttress 65 and a steel beam 66 in a jacking pipe working well, wherein a hydraulic jack is used as jacking power.
Fourthly, jacking the jacking pipe, namely constructing two phi 1.8m manual jacking pipes above the existing tunnel 3, and adopting a manual soil digging mode, so that operators can excavate soil layers in the jacking pipe range in advance, and then jacking the jacking pipe; the front earth excavation and jacking of the jacking pipe are controlled within 0.5m each time until the jacking pipe is jacked completely.
And fifthly, constructing a manual hole digging pile as a pulling-resistant pile, and digging downwards the manual hole digging pile with the diameter of 1.5m at the bottom of the upper pilot tunnel in the newly-built underground tunnel 4 above the two ends of the jacking pipe. When the pipe is excavated, the pipe is cut when the pipe is excavated and supported.
And sixthly, after the hole digging pile is excavated, placing a reinforcement cage 11 in the pile, wherein the length of a main reinforcement 111 in the reinforcement cage 11 is about 5 times larger than the diameter of a reinforcement of the design elevation of the section steel (I-steel 21) in the jacking pipe. The spiral stirrups 112 begin to be arranged at the bottom of the top pipe beam and end at the bottom of the hole digging pile. And then pouring concrete (namely, first concrete 12) in the hole digging pile, wherein the concrete in the pile is poured from the bottom of the hole digging pile to the designed elevation of the concrete cushion layer 23 in the jacking pipe.
And seventh, constructing beam stirrups in the top pipe, and pouring a concrete cushion layer 23 after the stirrups are installed. After the concrete cushion layer 23 reaches the design strength, the pile head concrete of the hole digging pile is broken, and the profile steel is arranged, wherein the profile steel adopts I-steel 21. Subsequently, the beam stirrup is welded with the i-steel 21. Finally, a deformed steel bar 24 is laid on the upper portion of the section steel, and the deformed steel bar 24 and the I-steel 21 are welded.
And eighth, after the arrangement of the section steel and the steel bars in the jacking pipe is completed, the hole digging pile is stretched into the jacking pipe beam, and the main steel bar higher than the section steel elevation is bent and then welded with the section steel. And then plugging one side of the jacking pipe, and installing an arc-shaped template 7 with the same shape as the initial support superposition part of the newly-built undercut tunnel 4 in the jacking pipe. And finally, pouring concrete of the rest parts in the jacking pipe to form the special-shaped bench beam structure. Schematic views of the connection of the main rib 111 and the section steel and the casting of the concrete in the jacking pipe are shown in fig. 9 and 10.
And ninth, excavating guide holes on the left side and the right side of the lower part of the tunnel, wherein the overlapped part of the jacking pipe and the primary support is sequentially cut off along with the excavation of the tunnel. The partition wall in the lower pilot tunnel is erected in time (which is a construction process in the prior art), and an initial support is constructed.
The working principle of the invention is as follows: the reinforcement measure of special-shaped bench beam is used as a uplift pile through constructing manual hole digging piles, and is reliably connected with the special-shaped top pipe beam to form a special-shaped bench beam, and the special-shaped bench beam is integrally ridden over the existing tunnel and used as a permanent protection structure thereof, so that unloading rebound caused by tunnel excavation is effectively resisted, and the structural safety and normal operation of the existing underlying tunnel are ensured. The top tube beams refer to the special-shaped top tube beam 2 unless otherwise specified in the invention.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (10)
1. The micro-deformation control method for the ultra-small clear distance of the large-section subway tunnel to span the existing tunnel is characterized by comprising the following steps in sequence:
constructing an upper left pilot tunnel and an upper right pilot tunnel at the design position of a newly built undercut tunnel by adopting a CRD method;
step two, excavating a pipe-jacking working well at one side of the existing tunnel, and excavating the pipe-jacking working well downwards at the bottom of the upper pilot tunnel of the newly-built undercut tunnel according to the design position of the starting point of the pipe jacking;
step three, after the pipe jacking working well is excavated, installing jacking equipment in the pipe jacking working well;
step four, jacking the jacking pipe, namely constructing two manual jacking pipes above the existing tunnel, adopting a manual soil digging mode, enabling operators to dig out soil layers in the jacking pipe range in advance, and jacking the jacking pipe;
step five, constructing a manual hole digging pile as an anti-pulling pile, digging downwards the manual hole digging pile at the bottom of an upper pilot tunnel in a newly built underground tunnel above two ends of a jacking pipe, and cutting the jacking pipe when encountering the jacking pipe along with supporting along with digging during digging;
step six, after the excavation of the hole digging pile is completed, placing a reinforcement cage in the hole digging pile, wherein the length of a main reinforcement in the reinforcement cage is 5 times larger than the diameter of a reinforcement with the design elevation of the section steel in the jacking pipe; the spiral stirrups are arranged from the bottom of the jacking pipe to the bottom of the hole digging pile; then pouring concrete in the hole digging pile, wherein the concrete is poured from the bottom of the hole digging pile to the height of the plain concrete cushion layer in the jacking pipe;
step seven, firstly constructing beam stirrups in the top pipe, and pouring plain concrete cushion layers after the beam stirrups are installed; after the plain concrete cushion layer reaches the design strength, chiseling the pile head concrete of the hole digging pile, starting to arrange the I-steel, welding the beam stirrup and the I-steel, paving the deformed bar on the upper part of the I-steel, and welding the deformed bar and the I-steel;
step eight, after the arrangement of the I-steel and the steel bars in the jacking pipe is completed, the hole digging pile is stretched into the jacking pipe, and after the main steel bar which is higher than the elevation of the I-steel is bent, the hole digging pile is welded with the I-steel; installing an arc-shaped template which is the same as the superposition part of the primary support of the newly-built undercut tunnel in the jacking pipe, plugging one side of the jacking pipe, and pouring concrete in the rest part of the jacking pipe;
and step nine, excavating a left lower pilot tunnel and a right lower pilot tunnel of the newly-built underground tunnel by adopting a CRD construction method, wherein the overlapped part of the jacking pipe and the primary support is sequentially cut off along with the excavation of the tunnel, erecting a partition wall in the pilot tunnel at the lower part of the tunnel in time, and constructing the primary support.
2. The micro-deformation control method for the ultra-small clear distance of the large-section subway tunnel to span the existing tunnel according to claim 1, wherein when the inner construction of the jacking pipe is carried out, the construction steps are sequentially paving beam stirrups into the hollow jacking pipe, pouring plain concrete cushion layers, paving I-steel on the plain concrete cushion layers, arranging threaded steel bars on the I-steel, welding the main reinforcement of a steel reinforcement cage with the I-steel after bending, installing an arc-shaped template, and pouring concrete into the jacking pipe.
3. The micro-deformation control method for the ultra-small clear distance of the large-section subway tunnel to span the existing tunnel according to claim 1, wherein when concrete is poured in the hole digging pile, pouring is stopped when the concrete reaches the height above a plain concrete cushion layer in the jacking pipe, after the concrete is solidified, pile head concrete is broken and a main reinforcement of a reinforcement cage is exposed, and the main reinforcement is bent into the jacking pipe and welded with I-steel.
4. The micro-deformation control method for the ultra-small clear distance of the large-section subway tunnel to span the existing tunnel according to claim 1, wherein the jacking equipment comprises a jack, a back rest, a guide rail support, a concrete buttress and a steel beam, the hydraulic jack is used as jacking power, the back rest and the concrete buttress are fixedly arranged in the jacking pipe working well, one end of the jack is fixedly connected with the back rest, the other end of the jack is used for pushing the jacking pipe, the jacking pipe slides on the guide rail, the guide rail is fixedly connected on the guide rail support, the guide rail support is fixedly connected on the steel beam, and the steel beam is fixedly connected on the concrete buttress.
5. The micro-deformation control method for the ultra-small clear distance of the large-section subway tunnel to span the existing tunnel according to claim 1, wherein the jacking process of the jacking pipe comprises the following steps in sequence: the equipment debugging operation, pipe discharging, pipe jacking in place, soil digging before pipe jacking, pipe jacking correction and pipe jacking process recording and management.
6. The micro-deformation control method for the ultra-small clear distance of the large-section subway tunnel to cross the existing tunnel according to claim 1, wherein the length of each soil excavation before pipe and each jacking length is determined according to geological conditions, and is generally controlled to be about 0.5m until all jacking pipes are jacked.
7. The micro-deformation control method for the ultra-small clear distance of the large-section subway tunnel to span the existing tunnel according to claim 1, wherein in the fifth step, the manual hole digging pile and the jacking pipe are perpendicular and orthogonal, the pile diameter of the manual hole digging pile is smaller than the pipe diameter of the jacking pipe, and then the upper surface and the lower surface of the intersection part of the jacking pipe and the hole digging pile are cut.
8. The micro-deformation control method for the ultra-small clear distance of the large-section subway tunnel to span the existing tunnel according to claim 7, wherein the step of cutting the jacking pipe sequentially comprises the following steps:
the cutting step of the upper surface of the jacking pipe is as follows: digging to the upper part of the jacking pipe, cleaning the cutting outline, applying artificial retaining wall, cleaning slag soil on the pipe wall, stacking sand bags at the cutting part inside the jacking pipe, plugging square timber above the sand bags, cutting in blocks, hanging out the cut steel pipe, withdrawing the square timber and the sand bags;
the lower surface cutting step of the jacking pipe is as follows: measuring and positioning the cutting profile, cleaning the slag soil on the pipe wall, cutting in blocks, and transporting out the cut steel pipe in the pipe jacking.
9. The micro-deformation control method for the ultra-small clear distance of the large-section subway tunnel to span the existing tunnel as claimed in claim 1, wherein the construction steps of the manual hole digging pile sequentially comprise:
constructing a locking collar beam and a first section of hole digging pile retaining wall, setting out a pile position, breaking a temporary inverted arch part of the pile position, digging the first section of hole digging pile, and constructing the locking collar beam and the first section of retaining wall, wherein the manual hole digging pile hole collar and the retaining wall adopt reinforced concrete structures;
pile body excavation, namely excavating layer by layer from top to bottom, wherein the excavation depth of each section during construction is 1m, the center line of the pile should be corrected at any time in the excavation process, and if deviation is found, the correction should be carried out in time;
constructing an artificial retaining wall, wherein the artificial retaining wall adopts a reinforced concrete structure, and is constructed to the pile bottom section by section along with the excavation of a pile hole, and the construction is sequentially and circularly carried out;
and (3) cutting the top pipe at the crossing part of the manual hole digging pile during the construction of the manual hole digging pile, and welding the manual retaining wall vertical steel bar above the top pipe with the top pipe after the top pipe cutting is completed.
10. The micro-deformation control method for the ultra-small clear distance of the large-section subway tunnel to span the existing tunnel, as claimed in claim 1, is characterized in that 3-4 barbs are welded at the bottom of a reinforcement cage in a manual hole digging pile, so that the barbs are inserted into the pile bottom to prevent the reinforcement cage from floating upwards when concrete is poured; before construction, groundwater is lowered to a position at least 1m below the designed pile bottom of the manual hole digging pile construction so as to ensure that soil in the pile hole is dry; the installation longitudinal gradient of the guide rail and the jack is consistent with the design gradient of the jacking pipe.
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