CN115391886B - System and method for analyzing stress between segment rings of oversized-diameter shield tunnel structure - Google Patents
System and method for analyzing stress between segment rings of oversized-diameter shield tunnel structure Download PDFInfo
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Abstract
The invention discloses a segment inter-ring stress analysis system and method of an oversized-diameter shield tunnel structure, wherein the system comprises a segment internal stress acquisition unit, a segment inter-ring stress acquisition unit and a dissipation rule analysis unit, wherein the segment internal stress acquisition unit comprises a plurality of groups of reinforcing steel bar dynamometers positioned on longitudinal embedded dynamometric steel bars of each segment; the inter-segment ring stress acquisition unit comprises a liner and a force measuring thimble. According to the invention, through an in-situ full-scale model test of the wind well, a dissipation process rule of longitudinal force transmission among the rings of the shield segment can be obtained, so that the problems of unclear stress distribution among the rings, difficulty in obtaining the dissipation rule and the like are solved, the problems of damage during segment assembly, overlarge opening and dislocation quantity caused by segment stress dissipation after jack retraction are solved, and in addition, a large amount of data are provided in the test, so that the defect that the values of segment design parameters have certain randomness and blindness is overcome.
Description
Technical Field
The invention belongs to the technical field of shield tunnel construction, and particularly relates to a segment inter-ring stress analysis system of an oversized-diameter shield tunnel structure, and a segment inter-ring stress analysis method of the oversized-diameter shield tunnel structure.
Background
In recent years, with the continuous advancement of national development strategy and infrastructure construction, and the further improvement of high-speed railway network, highway network and urban road network structures, more and more large-diameter shield tunnel engineering is generated. Although the current ultra-large diameter shield tunnel is widely applied, the current ultra-large diameter shield tunnel is still in a 'rough' construction and operation state, and problems generated in the construction and operation processes of the ultra-large diameter shield tunnel are more and more, such as fragmentation, seam opening, dislocation and the like of a segment structure of the shield tunnel frequently occur, and great threat is brought to the construction safety and structural service performance of the shield tunnel.
Aiming at the problems in the industry, the adopted method mainly comprises means of numerical analysis, model test, field monitoring and the like, however, the adopted method can not truly reflect the stress between segment rings of the tunnel structure of the ultra-large-diameter shield under the actual working condition, and is mainly embodied as follows:
(1) The selection basis of key design parameters of ultra-large diameter shield tunnel structure is lacking
Because of the existence of the shield segment ring and the longitudinal joint, the stress characteristics of the segment structure are obviously different from those of the common reinforced concrete structure, and the shield tunnel structure design method is more applied to correction of the usage and Liang spring model. The rigidity reduction coefficient in the correction inertial method and the bending moment improvement coefficient in the staggered joint assembly have great influence on the accuracy of calculating the deformation and the internal force of the segment; the accuracy of the calculation result is determined by the joint stiffness coefficient in the Liang spring model, which is also an important reason that the Liang spring model is not widely popularized in China, and meanwhile, the model is a three-ring assembly model, and stratum-structure response data under the in-situ condition is lacked, so that the value of the segment design parameter has certain randomness and blindness;
(2) Longitudinal force transmission mechanism and dissipation rule between segment rings under the action of shield jack are unknown
In the aspect of longitudinal stress research of shield tunnel segments, the longitudinal analysis of the whole tunnel structure is focused under the influence of adverse factors such as stratum deformation, load change, earthquake and the like, for example, the longitudinal equivalent continuous model and the longitudinal foundation beam-spring model are utilized to research the problems of longitudinal stress, deformation, circumferential seam opening and the like of the tunnel, and the focus is focused on the longitudinal response of the tunnel in an operation stage. However, in actual construction, the problems of fragmentation, seam opening, dislocation and the like of a shield tunnel segment structure frequently occur during tunnel construction, which are closely related to a force transmission mechanism between segment rings under the action of a jack, although a longitudinal force transmission and dissipation rule between related segment rings can be obtained by adopting a refined numerical calculation mode, the joint of every two adjacent segment rings bears the combined action of axial force, shearing force and bending moment, springs and contact units with different properties are needed, subjectivity is high, stress characteristics in a real state cannot be reproduced, and therefore, the stress distribution and dissipation rule between rings cannot be obtained, and the problems that the segments are broken during segment assembly caused by the problems, the expansion and dislocation amount caused by segment stress dissipation after the jack is retracted and the like cannot be solved.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects of the prior art and providing an improved segment inter-ring stress analysis system of an oversized-diameter shield tunnel structure.
Meanwhile, the invention also relates to a segment inter-ring stress analysis method of the ultra-large diameter shield tunnel structure.
In order to solve the technical problems, the invention adopts the following technical scheme: the utility model provides a super large diameter shield tunnel structure's section of jurisdiction interannular stress analysis system, its is used for in the full scale model test of wind-blown well normal position, and keeps the shield jack effect to obtain the stress of having assembled the section of jurisdiction ring or waiting to assemble the section of jurisdiction, section of jurisdiction interannular stress analysis system includes:
the device comprises a segment internal stress acquisition unit, a shield jack and a control unit, wherein the segment internal stress acquisition unit comprises a plurality of groups of steel bar dynamometers positioned on longitudinal embedded dynamometer bars of each segment, the plurality of groups of steel bar dynamometers are distributed at intervals along the arc length of the segment, a plurality of steel bar dynamometers are arranged in each group, the steel bar dynamometers are distributed at intervals inwards from the abutting end surface of the segment and the shield jack, and meanwhile, the stress level of the segment internal under the action of the jack is fed back through the steel bar dynamometers;
the inter-segment ring stress acquisition unit comprises a liner which is similar to the longitudinal splicing end face of the segment in shape and is attached to the longitudinal splicing end face of the segment, and a plurality of force measuring ejector pins which extend along the abutting direction of the shield jack, wherein one end of each force measuring ejector pin is embedded in the segment, the other end of each force measuring ejector pin penetrates out of the liner and abuts against the spliced segment, and the inter-segment stress of the corresponding segment or segment ring is acquired through the compression amount of the liner under the acting force of the shield jack;
and the dissipation rule analysis unit is respectively in signal communication with the reinforcement dynamometer and the dynamometer thimble, and obtains the inter-ring stress distribution and dissipation rule of the tunnel structure according to the obtained stress.
Preferably, the segment is divided into N segments in the longitudinal direction, each segment is equal to and forms n+1 segment surfaces, each group of reinforcing steel bar dynamometers is correspondingly arranged on the segment surface and is positioned on the shield jack abutting end surface and the M segment surface of the segment, wherein M is the segment surface where the middle part of the N segments is positioned.
Preferably, the duct piece longitudinal embedded force measuring bars are distributed in an arc shape in a middle of the duct piece ring, wherein a group of bar force measuring meters are correspondingly arranged on each duct piece longitudinal embedded force measuring bar.
Further, the force measuring bars are longitudinally embedded in the plurality of duct pieces to form a plurality of concentric arc rows, and the arc rows are uniformly distributed at intervals in the thickness direction of the duct pieces.
According to one specific implementation and preferred aspect of the invention, the shield jack corresponds to the segment longitudinal embedded dynamometer one by one and is abutted against the dynamometer.
Preferably, the length of each segment longitudinal embedded force measuring bar is at least 3/4 of the segment longitudinal length.
Preferably, each segment is longitudinally embedded with a force measuring bar from the end to face the abutting end of the shield jack of the segment.
According to still another specific implementation and preferred aspect of the present invention, the gasket is made of rubber and has a thickness of 4-10 mm, wherein the inter-ring stress of the corresponding segment or segment ring is obtained by the compression amount of the rubber under the action of the shield jack.
According to one specific implementation and preferred aspect of the invention, each segment ring comprises N arc segments assembled end to end, wherein N is more than or equal to 6 and is an integer; each arc segment is provided with a first arc end face and a second arc end face, the first arc end face is a collision end face contacted with the shield jack, the second arc end face is an assembled end face, the segment inter-ring stress acquisition unit further comprises a soil pressure gauge and a displacement gauge, the gasket is tiled on each arc segment assembled end face, the soil pressure gauge and the displacement gauge are arranged on the assembled end face, and can acquire inter-ring stress and relative displacement of two corresponding segment rings along with the compression amount of the gasket under the acting force of the shield jack, and the dissipation rule analysis unit is respectively communicated with the force measuring ejector pins, the soil pressure gauge and the displacement gauge information and acquires inter-ring stress distribution and dissipation rules of the tunnel structure according to acquired stress and displacement data.
Preferably, the gasket material is rubber and has a thickness of 4-10 mm. The gasket material is rubber (glued nitrile cork rubber gasket) and the thickness is 5mm, wherein the inter-ring stress of the corresponding pipe piece or pipe piece ring is obtained through the compression amount of the rubber under the acting force of the shield jack.
Preferably, the gasket is mounted on the face similar in shape to the face and aligned from the centre. The gasket not only can play the effect of being convenient for accurate acquisition of stress, but also can strengthen sealedly to a certain extent, reduces simultaneously that the opening of section of jurisdiction ring, the wrong platform volume is too big phenomenon emergence probability.
According to one specific and preferred aspect of the invention, the force-measuring thimble has four force-measuring thimble and is distributed at four corners of the pad, and the soil pressure gauge and the displacement gauge are distributed in the area formed by the four force-measuring thimble. The force measuring points are ensured not to interfere with each other, so that the accuracy of accurate stress acquisition is ensured.
According to a further specific and preferred aspect of the invention, the earth pressure gauge is located partly inside the arcuate segment and partly inside the liner, the displacement gauge is penetrating the liner and the outer end surface is flush with the outer end surface of the liner, wherein the displacement gauge is capable of monitoring the displacement of the segment ring both longitudinally and radially. That is, the pad can also function to protect the earth pressure gauge and the displacement gauge, extending the service life, to facilitate the acquisition of stresses.
Preferably, the displacement meter is a vibrating wire type displacement meter, and the vibrating wire type displacement meter is a plurality of the vibrating wire type displacement meters, wherein the plurality of the vibrating wire type displacement meters are distributed at intervals along the arc center line of the assembled end face.
Further, the soil pressure gauge has a plurality of, and with displacement meter dislocation interval distribution is in assembling terminal surface arc central line place regional. Reasonable layout and more accurate acquisition of required data.
In addition, n=6, and the segment ring is composed of one capping block (F) segment, two adjacent blocks (L1, L2), six standard blocks (B1, B2, B3, B4, B5, B6). By the arrangement, stress and displacement data are obtained more effectively, and meanwhile, assembly of the segment ring (especially for a tunnel structure of a shield with an ultra-large diameter) is facilitated.
Preferably, the inter-segment ring stress acquisition unit further comprises a fiber bragg grating displacement meter arranged at the splicing position of every two adjacent segment rings, wherein the fiber bragg grating displacement meter is provided with two connecting ends, the two connecting ends are respectively fixed with the two assembled arc segments, and the fiber bragg grating displacement meter acquires longitudinal displacement between the two assembled adjacent segment rings. Therefore, not only can the needed data be obtained at the splicing gap, but also the longitudinal displacement can be further effectively obtained through the external fiber bragg grating displacement meter of the segment ring.
Further, the fiber bragg grating displacement meters are multiple, and are uniformly distributed on the inner wall of the segment ring around the circumference of the segment ring, wherein at least one fiber bragg grating displacement meter is distributed on each arc segment.
In addition, the shield segment ring stress analysis system further comprises a soil pressure box, a flexible soil pressure gauge, a concrete strain gauge, a bolt shaft force gauge and an annular steel bar stress gauge, wherein the soil pressure box and the flexible soil pressure gauge are uniformly distributed at intervals around the circumference of the segment ring at the outer side of the segment ring, and two soil pressure boxes are distributed between every two adjacent flexible soil pressure gauges; the concrete strain gauges are distributed at the middle part and two ends of each arc-shaped duct piece; the annular steel bar stress gauge is arranged close to the concrete strain gauge in the middle; the bolt shaft force meters are distributed at the longitudinal joint of the segment ring.
The other technical scheme of the invention is as follows: the method for analyzing the inter-segment ring stress of the oversized-diameter shield tunnel structure adopts the inter-segment ring stress analysis system of the oversized-diameter shield tunnel structure and comprises the following steps:
s1, obtaining the internal stress of a segment, which is obtained by a plurality of groups of reinforcing steel bar dynamometers;
s2, obtaining the inter-ring stress of the corresponding pipe piece or pipe piece ring through a force measuring thimble according to the compression amount of the liner under the acting force of the shield jack;
s3, obtaining the inter-ring stress distribution and dissipation rule of the tunnel structure, and screening and analyzing based on the data obtained in S1 and S2.
Due to the implementation of the technical scheme, compared with the prior art, the invention has the following advantages:
according to the invention, through an in-situ full-scale model test of the wind well, the longitudinal stress between pipe piece rings and the internal stress of the pipe pieces can be obtained under the action of construction factors such as the thrust of a shield jack and the pipe piece assembling mode, and meanwhile, the dissipation process rule of the longitudinal force transmission between the pipe pieces of the shield is obtained, so that the problems that the stress distribution between rings is unknown, the dissipation rule is difficult to obtain and the like are solved, the damage during pipe piece assembling can be avoided, the problems of overlarge opening and dislocation quantity caused by the dissipation of the pipe piece stress after the jack is retracted are solved, and in addition, a large amount of data are provided in the test, so that the defect that the value of the pipe piece design parameter has certain randomness and blindness is overcome.
Drawings
FIG. 1 is a schematic diagram (simplified) of the working principle of the inter-segment hoop stress analysis system of the present invention;
FIG. 2 is a schematic view of the arrangement of the segment internal force monitoring points according to the present invention;
fig. 3 is a schematic view of circumferential arrangement of reinforcement force measuring meters on a segment longitudinal embedded force measuring reinforcement bar according to the present invention;
fig. 4 is a schematic view of a longitudinal rebar dynamometer layout of the present invention (jack-facing side);
FIG. 5 is a schematic view of the force-measuring thimble arrangement of the present invention (the jack-facing side);
fig. 6 is a schematic view of the arrangement of the combination of the longitudinal bar stress gauge and the force-measuring thimble of the present invention (the jack-facing side);
FIG. 7 is a schematic front view of a shield segment ring stress analysis system according to the present invention;
FIG. 8 is a schematic axial distribution of the segment ring of FIG. 7;
FIG. 9 is a schematic view of the arcuate segment of FIG. 8;
FIG. 10 is a schematic view of an assembled end face of the arcuate segment of FIG. 9;
FIG. 11 is a schematic view of the distribution of soil pressure around a tunnel according to the present invention;
FIG. 12 is a schematic view showing the distribution of the load of each part along the longitudinal direction of the tunnel;
wherein: A. a segment inter-ring stress acquisition unit; a1, a liner; a2, measuring force thimble; a3, a soil pressure gauge; a4, a displacement meter; a5, a fiber bragg grating displacement meter;
B. a dissipation rule analysis unit;
g. arc-shaped duct pieces; g1, a first arc-shaped end face; and g2, a second arc-shaped end face.
H. Segment ring; J. a wind shaft; D. shield jack (jack).
Detailed Description
In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is, however, susceptible of embodiment in many other forms than those described herein and similar modifications can be made by those skilled in the art without departing from the spirit of the application, and therefore the application is not to be limited to the specific embodiments disclosed below.
As shown in fig. 1 to 10, the inter-segment ring stress analysis system of the large-diameter shield tunnel structure of the embodiment is used for an in-situ full-scale model test of a wind well, and acquires the stress of an assembled segment ring or a segment to be assembled under the action of a shield jack.
Specifically, the block type of '6+2+1' is adopted, namely, the block type consists of 1 block of sealing top block (F) segment, 2 blocks of adjacent blocks (L1 and L2) and 6 blocks of standard blocks (B1-B6).
The corresponding ring numbers of the wind well in-situ full-scale model test are 1306-1313 rings and 1314-1321 rings respectively, wherein the main test rings are selected according to a symmetrical and central principle, two rings at the end boundary are removed, the 1309 th, 1312 nd, 1315 th and 1318 th ring numbers are sequentially selected as the main test rings at the 5-equally-divided position of the test area, two stratum subareas respectively occupy two rings, four rings are summed, and the rest rings are used as auxiliary test rings.
In this example, taking a main test ring as an example, the related shield segment ring stress analysis system includes a segment internal stress acquisition unit, a segment inter-ring stress acquisition unit, and a dissipation rule analysis unit.
The segment internal stress acquisition unit comprises a plurality of groups of steel bar dynamometers positioned on each segment longitudinal embedded force measuring steel bar, wherein the steel bar dynamometers are distributed at the steel bars within the range of 1m of the longitudinal depth of the boss on the side of the segment facing the jack so as to acquire the spatial distribution data of the segment along the longitudinal stress under the action of the jack thrust.
Specifically, the F-block duct pieces are uniformly distributed with 2 rows of measuring points along the circumferential direction, and the B-block and the L-block are uniformly distributed with 3 rows along the circumferential direction; the F block, the B block and the L block are all arranged in 3 columns along the longitudinal direction.
Each group of reinforcing steel bar dynamometers is provided with 3 reinforcing steel bar dynamometers, the reinforcing steel bar dynamometers are distributed at intervals inwards from the abutting end surface of the pipe piece and the shield jack, and the reinforcing steel bar dynamometers are used for feeding back the stress level in the pipe piece under the action of the jack.
The length of the segment in the longitudinal direction is 2000mm, the thickness is 650mm, and the spacing in the longitudinal direction is 500mm.
The length of each segment longitudinal embedded force measuring bar is 1550mm, and each segment longitudinal embedded force measuring bar is aligned with the abutting end face of the shield jack of the segment from the end part.
6 longitudinal embedded force measuring bars of the duct piece are distributed in an arc shape by taking the middle of the duct piece ring as a circle, wherein a group of steel bar force measuring meters are correspondingly arranged on each longitudinal embedded force measuring bar of the duct piece.
The 6 longitudinal pre-buried dynamometric bars of section of jurisdiction form 2 arc rows of concentric centers, and wherein 2 arc rows are evenly spaced apart in section of jurisdiction thickness direction, and shield jack and the longitudinal pre-buried dynamometric bars of section of jurisdiction one-to-one simultaneously are contradicted on the bar dynamometer.
Referring to fig. 7 to 10, in this example, a segment ring H is composed of a single capping block (F), two adjacent blocks (L1, L2), and six standard blocks (B1, B2, B3, B4, B5, B6). By the arrangement, stress and displacement data are obtained more effectively, and meanwhile, assembly of the segment ring (especially for a tunnel structure of a shield with an ultra-large diameter) is facilitated.
In this example, taking the standard block B1 as an example, the arc segment g has a first arc end surface g1 and a second arc end surface g2, where the first arc end surface g1 is an abutting end surface contacting with the shield jack D, and the second arc end surface g2 is an assembling end surface.
In this example, the shield segment ring stress analysis system comprises a segment ring stress acquisition unit A and a dissipation rule analysis unit B.
The inter-segment ring stress acquisition unit A comprises a liner a1, a force measuring thimble a2, a soil pressure meter a3, a displacement meter a4 and a fiber grating displacement meter a5.
The gasket a1 is mounted on the assembled end face in a similar shape to the assembled end face and aligned from the center. The gasket not only can play the effect of being convenient for accurate acquisition of stress, but also can strengthen sealedly to a certain extent, reduces simultaneously that the opening of section of jurisdiction ring, the wrong platform volume is too big phenomenon emergence probability.
In this example, the pad a1 is made of rubber (a glued nitrile cork rubber pad) and has a thickness of 5mm, wherein the inter-ring stress of the corresponding pipe piece or pipe piece ring is obtained through the compression amount of the rubber under the acting force of the shield jack D.
The number of the force measuring ejector pins a2 is four, one end of each force measuring ejector pin is embedded in the arc-shaped duct piece g, and the other end of each force measuring ejector pin penetrates out of the liner a1 and is abutted against the assembled duct piece.
Four force measuring ejector pins a2 are distributed at four corners of the pad a 1.
The earth pressure gauge a3 and the displacement gauge a4 are arranged on the assembled end surfaces, and can acquire the inter-ring stress and the relative displacement of the two corresponding segment rings H along with the compression amount of the gasket a1 under the acting force of the shield jack d.
The soil pressure gauge a3 and the displacement gauge a4 are distributed in an area formed by four force measuring ejector pins. The force measuring points are ensured not to interfere with each other, so that the accuracy of accurate stress acquisition is ensured.
The soil pressure gauge a3 is partially positioned in the arc-shaped duct piece, the displacement gauge a4 penetrates out of the liner, the outer end face is flush with the outer end face of the liner a1, and the displacement gauge a4 can monitor the longitudinal and radial displacement of the duct piece ring H. That is, the pad can also function to protect the earth pressure gauge and the displacement gauge, extending the service life, to facilitate the acquisition of stresses.
The displacement meters a4 are vibrating wire type displacement meters, and a plurality of vibrating wire type displacement meters are arranged, wherein the plurality of vibrating wire type displacement meters are distributed at intervals along the arc center line of the assembled end face.
In this example, there are a plurality of soil pressure gauges a3, and the soil pressure gauges a4 are distributed in the area where the arc center line of the assembled end face is located at staggered intervals. Reasonable layout and more accurate acquisition of required data.
The fiber bragg grating displacement meter a5 is arranged at the splicing position of every two adjacent segment rings H, wherein the fiber bragg grating displacement meter a5 is provided with two connecting ends, the two connecting ends are respectively fixed with the two assembled arc segment rings, and the fiber bragg grating displacement meter a5 obtains the longitudinal displacement between the two assembled adjacent segment rings. Therefore, not only can the needed data be obtained at the splicing gap, but also the longitudinal displacement can be further effectively obtained through the external fiber bragg grating displacement meter of the segment ring.
In this example, there are a plurality of fiber grating displacement meters a5, and evenly distributed on the inner wall of the segment ring H around the circumference of the segment ring H, wherein at least one fiber grating displacement meter a5 is distributed on each arc segment.
The dissipation rule analysis unit B is respectively communicated with the force measuring thimble a2, the soil pressure meter a3 and the displacement meter a4 in information, and is obtained according to the information.
In addition, the shield segment ring stress analysis system further comprises a soil pressure box, a flexible soil pressure gauge, a concrete strain gauge, a bolt shaft force gauge and an annular steel bar stress gauge.
The soil pressure boxes and the flexible soil pressure gauges are uniformly distributed at the outer side of the duct piece ring at intervals around the circumference of the duct piece ring, and two soil pressure boxes are distributed between every two adjacent flexible soil pressure gauges.
In this example, the total number of the flexible soil pressure gauges and the soil pressure boxes is 12, wherein the number of the flexible soil pressure gauges is 4, and the number of the soil pressure boxes is 8.
The concrete strain gauges are distributed at the middle part and two ends of each arc-shaped duct piece.
The annular steel bar stress gauge is arranged close to the middle part concrete strain gauge.
The bolt axial force meter is distributed at the longitudinal seam of the segment ring.
In addition, the data of each stress meter, each strain gauge and each pressure meter are analyzed through the dissipation rule analysis unit, inversion analysis is carried out by combining test data, and a reasonable segment structure calculation parameter value range and a reasonable suggestion value are summarized.
Then, through the in-situ full-scale model test of the wind shaft, the longitudinal stress between the segment rings and the internal stress of the segment can be obtained under the action of construction factors such as the grouting pressure behind the wall, the jack thrust of the shield machine, the segment assembling mode and the like, and meanwhile, the dissipation process rule of the longitudinal force transmission between the shield segment rings is obtained, so that the problems that the stress distribution between the rings is unknown, the dissipation rule is difficult to obtain and the like are solved, the segment can be broken during assembling, and the problems of opening and overlarge staggered quantity caused by the dissipation of the segment stress after the jack is retracted are solved.
Meanwhile, in the embodiment, the analysis process of the three-dimensional numerical analysis model of the longitudinal force dissipation rule of the shield tunnel mainly comprises the following steps:
1. building a shield model: and establishing a shield tunnel numerical model of the 16-ring segment by finite element software.
2. Analysis of simulation conditions: and analyzing according to the whole shield construction process, and selecting a load space-time subsection model of the two stages of the splicing stage and the releasing stage.
3. Main load of construction stage
(1) Jack thrust: belongs to one of main loads received by the segment in the construction stage of the shield tunnel, is also one of reasons for causing segment cracking in the construction stage, and particularly when the circular seam surface of the segment is uneven due to construction or manufacturing errors, even if the height difference is only 0.5-1.0 mm, the next circular pipe segment can generate extremely large splitting moment. Meanwhile, the center of the jack supporting shoe is deviated, and the segment can be cracked. In the process of the numerical analysis of the special subject, jack thrust is simplified into pressure load acting on the annular seam backing plate.
(2) Grouting pressure: the distribution is complex, and uneven grouting pressure can cause dislocation and even cracking of the pipe piece. The grouting pressure is linearly reduced along the axial direction of the tunnel, and finally the pressure is reduced to the same pressure of surrounding soil layers. At present, the shield construction basically uses a synchronous grouting technology, and the pressure range is 0.4-0.5 MPa.
(3) Surrounding soil layer pressure: the soil pressure mode of action of fig. 11 is adopted, wherein P1 is the overburden soil pressure at the top of the segment ring, P2 is the soil resistance and vertical water pressure at the bottom of the segment ring, P3 is the lateral soil pressure on the horizontal plane at the top of the segment ring, P4 is the lateral soil pressure on the horizontal plane at the bottom of the segment ring, and P5 is the dead weight of the segment. And simulating and calculating the lateral soil pressure caused by the deformation of the segment ring by using the contact force between the soil finite element grid and the segment ring finite element grid in the model. And setting formation conditions based on backfill in the prototype test.
(4) Extrusion force of shield shell and shield tail brush to segment: when the shield machine is in meandering or needs to turn, the attitude of the shield machine is adjusted. When the attitude control of the shield tunneling machine is not matched with the curve section or the meandering amount is too large, the shield tail brush and even the shield shell can squeeze the segment, so that the segment is deformed in torsion and cracked, and the load born by a section of tunnel can be simplified into a load system shown in fig. 12 by combining the loads.
4. Material model and primary parameter selection
(1) Segment concrete (modulus of elasticity, poisson's ratio, density);
(2) Bolts (modulus of elasticity, poisson's ratio);
(3) The rubber water stop strip and the backing plate adopt Mooney-Rivlin first-order constitutive models;
(4) Shield shell (modulus of elasticity, poisson's ratio);
(5) Shield tail brush (elastic modulus, poisson's ratio)
(6) Soil layer (elastic modulus, poisson's ratio)
5. Three-dimensional finite element meshing: all parts of the model, namely the duct piece, the bolt, the water stop bar, the backing plate, the shield shell, the shield tail brush and the soil layer, adopt eight-node three-dimensional entity units. The longitudinal seam gaskets and the circular seam gaskets are connected by adopting a contact method. And a contact surface is also adopted to establish connection between the duct piece and the surrounding soil layer and between the duct piece and the shield tail brush. And applying initial strain to the three-dimensional solid unit of the simulation bolt so as to simulate the application of pre-tightening torque to the bolt in construction. The horizontal direction is the X axis, the vertical direction is the Y axis, and the Z axis forward direction is the same as the pushing direction of the shield machine.
6. Calculation results and analysis: and according to the result file, analyzing and summarizing the spatial distribution and dissipation rule of the longitudinal stress between the tunnel rings of the shield segment under the action of the jack.
The present invention has been described in detail with the purpose of enabling those skilled in the art to understand the contents of the present invention and to implement the same, but not to limit the scope of the present invention, and all equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of the present invention.
Claims (10)
1. The utility model provides a super large diameter shield tunnel structure's section of jurisdiction interannular stress analysis system, its is used for in the full scale model test of wind-blown well normal position, and keeps the shield jack effect to obtain the stress of having assembled the section of jurisdiction ring or waiting to assemble the section of jurisdiction, its characterized in that, section of jurisdiction interannular stress analysis system includes:
the device comprises a segment internal stress acquisition unit, a shield jack and a control unit, wherein the segment internal stress acquisition unit comprises a plurality of groups of steel bar dynamometers positioned on longitudinal embedded dynamometer bars of each segment, the plurality of groups of steel bar dynamometers are distributed at intervals along the arc length of the segment, a plurality of steel bar dynamometers are arranged in each group, the steel bar dynamometers are distributed at intervals inwards from the abutting end surface of the segment and the shield jack, and meanwhile, the stress level of the segment internal under the action of the jack is fed back through the steel bar dynamometers;
the inter-segment ring stress acquisition unit comprises a gasket which is similar to the longitudinal splicing end face of the segment in shape and is attached to the longitudinal splicing end face of the segment, and a plurality of force measuring ejector pins which extend along the abutting direction of the shield jack, wherein each segment ring comprises N arc segments spliced end to end, N is more than or equal to 6, and N is an integer; each arc-shaped duct piece is provided with a first arc-shaped end face and a second arc-shaped end face, the first arc-shaped end face is an abutting end face contacted with the shield jack, the second arc-shaped end face is an assembling end face, one end of each force measuring thimble is embedded in the duct piece from the assembling end face, and the other end of each force measuring thimble penetrates out of the liner and abuts against the assembled duct piece;
and the dissipation rule analysis unit is respectively in signal communication with the reinforcement dynamometer and the dynamometer thimble, and obtains the inter-ring stress distribution and dissipation rule of the tunnel structure according to the obtained stress.
2. The segment inter-ring stress analysis system of the oversized shield tunnel structure of claim 1, wherein: the segment is divided into N sections in sequence in the longitudinal direction, each section is equal, each group of reinforcing steel bar dynamometers are correspondingly arranged on the sectional surface and are positioned on the shield jack abutting end surface and the M-th sectional surface of the segment, wherein M is the sectional surface where the middle part of the N sections is positioned.
3. The segment inter-ring stress analysis system of the oversized shield tunnel structure of claim 2, wherein: the pipe piece longitudinal embedded force measuring bars are distributed in an arc shape in a middle of the pipe piece ring, and a group of steel bar force measuring meters are correspondingly arranged on each pipe piece longitudinal embedded force measuring bar.
4. The segment inter-ring stress analysis system of an oversized-diameter shield tunnel structure of claim 3, wherein: the plurality of the segment longitudinal embedded force measuring bars form a plurality of concentric arc rows, wherein the plurality of the arc rows are uniformly distributed at intervals in the thickness direction of the segment, and the length of each segment longitudinal embedded force measuring bar is at least 3/4 of the longitudinal length of the segment.
5. The segment inter-ring stress analysis system of the oversized shield tunnel structure of claim 4, wherein: the shield jack corresponds to the segment longitudinal embedded dynamometric bars one by one and is abutted against the bar dynamometer; and each segment longitudinal embedded force measuring bar is aligned with the abutting end face of the shield jack of the segment from the end part.
6. The segment inter-ring stress analysis system of the oversized shield tunnel structure of claim 1, wherein: the inter-segment ring stress acquisition unit further comprises a soil pressure gauge and a displacement gauge, the gaskets are tiled on the spliced end surfaces of each arc segment, the soil pressure gauge and the displacement gauge are arranged on the spliced end surfaces, the inter-segment ring stress and the relative displacement of the two corresponding segment rings can be acquired along with the compression quantity of the gaskets under the acting force of the shield jack, and the dissipation rule analysis unit is respectively communicated with the force measuring thimble, the soil pressure gauge and the displacement gauge in information and is used for acquiring inter-segment stress distribution and dissipation rules of the tunnel structure according to the acquired stress and displacement data.
7. The segment inter-ring stress analysis system of the oversized shield tunnel structure of claim 6, wherein: the gasket is made of rubber and has a thickness of 4-10 mm; the gasket is installed on the assembled end face in a similar shape to the assembled end face and aligned from the center.
8. The segment inter-ring stress analysis system of the oversized shield tunnel structure of claim 6, wherein: the four force measuring ejector pins are distributed at four corners of the liner, and the soil pressure gauge and the displacement gauge are distributed in an area formed by the four force measuring ejector pins; and/or the soil pressure gauge part is positioned in the liner and the inner part of the arc-shaped duct piece is positioned in the liner, the displacement gauge penetrates out of the liner, and the outer end face is flush with the outer end face of the liner, wherein the displacement gauge can monitor the longitudinal and radial displacement of the duct piece ring; and/or the displacement meter is a vibrating wire type displacement meter, and a plurality of vibrating wire type displacement meters are arranged, wherein the plurality of vibrating wire type displacement meters are distributed at intervals along the arc center line of the assembled end face; and/or the soil pressure gauges are arranged in a plurality of areas where the arc center lines of the assembled end faces are arranged at intervals and staggered with the displacement gauges.
9. The segment inter-ring stress analysis system of the oversized shield tunnel structure of claim 6, wherein: the inter-segment ring stress acquisition unit further comprises fiber bragg grating displacement meters arranged at the splicing position of every two adjacent segment rings, wherein each fiber bragg grating displacement meter is provided with two connecting ends, the two connecting ends are respectively fixed with the two assembled arc segments, and the fiber bragg grating displacement meters acquire longitudinal displacement between the two assembled adjacent segment rings; and/or the fiber bragg grating displacement meters are multiple and uniformly distributed on the inner wall of the segment ring around the circumference of the segment ring, wherein at least one fiber bragg grating displacement meter is distributed on each arc segment.
10. A segment inter-ring stress analysis method of an oversized-diameter shield tunnel structure is characterized by comprising the following steps of: a segment inter-ring stress analysis system employing the oversized shield tunnel structure of any of claims 1 to 9, and comprising the steps of:
s1, obtaining the internal stress of a segment, which is obtained by a plurality of groups of reinforcing steel bar dynamometers;
s2, obtaining the inter-ring stress of the corresponding pipe piece or pipe piece ring through a force measuring thimble according to the compression amount of the liner under the acting force of the shield jack;
s3, obtaining the inter-ring stress distribution and dissipation rule of the tunnel structure, and screening and analyzing based on the data obtained in S1 and S2.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20120063257A (en) * | 2010-12-07 | 2012-06-15 | 한국건설기술연구원 | Segment structure of shield tunnel making use of a prestressed steel wire and segment lining system fixing the segment therewith |
| CN209670980U (en) * | 2019-01-03 | 2019-11-22 | 浙江交工集团股份有限公司 | A kind of tunneling shield section of jurisdiction site monitoring system |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20120063257A (en) * | 2010-12-07 | 2012-06-15 | 한국건설기술연구원 | Segment structure of shield tunnel making use of a prestressed steel wire and segment lining system fixing the segment therewith |
| CN209670980U (en) * | 2019-01-03 | 2019-11-22 | 浙江交工集团股份有限公司 | A kind of tunneling shield section of jurisdiction site monitoring system |
Non-Patent Citations (1)
| Title |
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| "超大直径盾构隧道横通道开口形状对主体结构的影响分析";庞康等;《特种结构》;第38卷(第4期);第113-119页 * |
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