CN111044370A - Mechanical property test method for duct piece joint - Google Patents
Mechanical property test method for duct piece joint Download PDFInfo
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- CN111044370A CN111044370A CN201911317188.1A CN201911317188A CN111044370A CN 111044370 A CN111044370 A CN 111044370A CN 201911317188 A CN201911317188 A CN 201911317188A CN 111044370 A CN111044370 A CN 111044370A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
- G01N3/12—Pressure testing
Abstract
The invention relates to a mechanical property test method of a duct piece joint, which comprises the steps of firstly, selecting a test piece, determining a joint part of the test piece as a test object, determining a test loading mode, a displacement boundary condition and a loading working condition, then carrying out a rotational rigidity test and an inter-ring bending moment transmission test on the duct piece joint, finally, collecting test data, completing the joint rotational rigidity test and the inter-ring bending moment transmission test of the duct piece joint, obtaining the stress mechanism of the duct piece joint under different loading working conditions and the change rule of the bearing capacity and the rigidity of the duct piece joint, and obtaining the key design parameters of the duct piece joint.
Description
Technical Field
The invention relates to a pipe sheet joint, in particular to a method for testing the mechanical property of the pipe sheet joint.
Background
Because the deep drainage tunnel bears high internal water pressure and large external water and soil load, the deep drainage tunnel is greatly different from common highway tunnels, subway tunnels and the like in the aspects of calculation theory, construction technology, design and construction. In view of the change of the stress mode of the deep drainage tunnel lining, the reasonable structure type of the duct piece and the duct piece connecting mode need to be deeply researched, the duct piece with high bearing capacity is developed, and the duct piece connecting piece capable of bearing high internal water pressure is developed. On the basis, a segment mechanical behavior test needs to be carried out for optimizing the design and calculation theory of the lining segment and ensuring that the deep drainage shield tunnel lining structure can meet the requirement of bearing capacity under the action of external water and soil pressure and internal water pressure.
At present, the existing segment correlation tests mainly comprise a flat plate joint test and a full-ring segment test. The flat plate joint test has the problem that the mechanical behavior of the segment joint under the load action is difficult to accurately reflect due to the fact that the difference between the test piece shape and the actual segment shape is large.
Although the whole-loop test is accurate, the single test investment is overlarge, the test repeatability is low, the test result discreteness is high, and the result reliability is low.
Therefore, a 1:1 segment joint type is needed to be adopted to deeply probe the mechanical property and the failure mode of the segment joint of the shield tunnel, and specifically, the test contents are as follows:
1. testing the rotational rigidity of the joint;
2. and (4) testing the bending moment transmission between rings.
Disclosure of Invention
The invention provides a method for testing the mechanical property of a pipe piece joint, aiming at collecting and analyzing test data by reasonably selecting a 1:1 pipe piece joint test piece and testing according to different load working conditions to meet the test requirements in the background technology.
In order to achieve the purpose, the technical scheme of the invention is as follows: a mechanical property test method for a duct piece joint comprises the steps of firstly, selecting a test piece, determining a joint part of the test piece as a test object, determining a test loading mode, a displacement boundary condition and a loading working condition, then carrying out a rotational rigidity test and an inter-ring bending moment transmission test on the duct piece joint, finally, collecting test data, completing the joint rotational rigidity test and the inter-ring bending moment transmission test of the duct piece joint, obtaining a stress mechanism, a bearing capacity and a rigidity change rule of the duct piece joint under different loading working conditions, and obtaining key design parameters of the duct piece joint.
Furthermore, a 1:1 duct piece joint test piece is adopted, the form of the test piece is consistent with that of an actual duct piece, the test precision can be guaranteed, the repeatability is high, and the test cost is low.
Further, a loading mode and a displacement boundary condition of the test piece are simplified, a rotational stiffness test of the segment joint is simplified into a vertical and horizontal bidirectional loading mode, an inter-ring bending moment transmission test is simplified into a vertical, horizontal and longitudinal three-way loading mode, and the displacement boundary condition is simplified into that one end of the displacement boundary condition is a fixed hinged support and the other end of the displacement boundary condition is a sliding hinged support.
Furthermore, according to different water pressures in the tunnel and different assumed bending stiffness efficiency of the joint, the loading test working conditions are drawn up in a grading mode, and then the working condition load is determined according to the eccentricity of the joint.
5. The mechanical property test method of the segment joint according to claim 4, characterized in that: and carrying out continuous loading tests on the test specimen under various working conditions according to the determined loading working conditions until the test specimen is damaged, so that the test investment is greatly reduced.
Furthermore, automatic measuring equipment is adopted to actually measure the opening amount of the segment joint, the stress of a joint bolt, the position of the joint, the concrete strain of the hand hole position, the stress of a reinforcing steel bar and the deformation of the segment in the test process.
The invention has the beneficial effects that:
according to the invention, through a series of test steps of test piece selection, test loading mode and displacement boundary condition determination, loading working condition determination, loading test, test data acquisition and the like, a joint rotation rigidity test and an inter-ring bending moment transmission test of a 1:1 duct piece joint test are completed, the stress mechanism of the duct piece joint under different loading working conditions and the change rules of the bearing capacity and the rigidity of the duct piece joint are obtained, and key design parameters of the duct piece joint are obtained.
Drawings
FIG. 1 is a flow chart of an experiment of the present invention;
FIG. 2 is a schematic diagram showing the construction of a test piece for rotational stiffness test of a joint;
wherein (a) is a longitudinal sectional view, (b) is a top view;
FIG. 3 is a schematic view showing the structure of a test piece for an inter-ring bending moment transfer test;
wherein (a) is a longitudinal sectional view, (b) is a top view;
FIG. 4 is a joint load displacement boundary condition;
wherein: (a) positive bending moment, (b) negative bending moment;
FIG. 5 is a schematic view of an inter-ring bending moment transfer test load;
wherein (a) a longitudinal sectional view, (b) a horizontal view, (c) a top view;
FIG. 6 is a graph of joint load calculation (positive eccentricity);
FIG. 7 is a graph of joint load calculation (negative offset);
FIG. 8 is a trial loading flow chart;
FIG. 9 is a joint flare angle (flare amount) measurement point arrangement;
FIG. 10 is a concrete strain gauge arrangement;
FIG. 11 is a rebar gauge point layout;
FIG. 12 is a segment displacement gauge arrangement;
wherein (a) is a longitudinal sectional view, (b) is a top view;
FIG. 13 is an inter-ring bending moment transfer test point arrangement.
Detailed Description
The invention is further described with reference to the following figures and examples.
As shown in figure 1, the mechanical property test method of the segment joint comprises the following steps:
selecting test pieces
According to the purpose of the test, the part of the whole ring tube piece where the left ring tube piece B1 and the right ring tube piece B2 meet, namely the joint 1 part is selected as a test object. Test pieces (shown in fig. 2(a), (b)) were selected for the joint rotational stiffness test, and test pieces (shown in fig. 3(a), (b)) were selected for the inter-ring bending moment transfer test.
Secondly, determining a test loading mode and displacement boundary conditions
Aiming at the joint rotation rigidity test, the axial force borne by the segment joint is simulated by adopting horizontal loading, and the bending moment borne by the segment joint is simulated by adopting vertical loading. According to different stress modes of the joint, the working condition of positive bending moment and the working condition of negative bending moment are divided into two types, as shown in fig. 4(a) and (b). According to the actual stress condition of the joint, the load displacement boundary condition of the joint test piece in the test adopts a fixed hinged support at one end and a sliding hinged support at the other end.
Aiming at the bending moment transfer test between rings, the axial force between longitudinal pipe pieces needs to be simulated by adding a longitudinal load F on the basis of a horizontal load N and a vertical load P. As shown in fig. 3(a), (b), 5(a), (b), and (c), according to the actual stress condition of the joint, the load displacement boundary condition of the joint test piece in the test adopts a fixed hinged support at one end and a sliding hinged support at the other end, which is consistent with the joint rotational stiffness test.
Thirdly, determining the loading condition
And (4) setting up the loading test working condition according to different internal water pressures borne by the tunnel and the difference of the assumed joint bending rigidity efficiency. The internal water pressure is selected from 0 to the design limit state according to each level of 0.1MPa, and the bending rigidity of the joint is effectively selected from 1 to the minimum value of the design consideration according to each level of 0.1, so that the joint is arranged and combined to obtain the loading working condition.
And aiming at the joint rotational stiffness test, calculating the load corresponding to each working condition of positive and negative bending moments according to a theoretical mode.
Aiming at the inter-ring bending moment transfer test, the load corresponding to each working condition of positive bending moment is calculated according to a theoretical mode, and the longitudinal load is determined according to the design load.
And in the loading grade consideration test process, the principle of improving the utilization efficiency of a single group of test pieces as much as possible is adopted, and the loading grades are arranged from small to large according to the damage possibility of the test pieces.
1) Positive eccentricity regime
In the test, PV、PHThe relationship with eccentricity can be determined according to fig. 6. The eccentricity e at the joint is defined as M/N (M, N is positive in the direction shown, i.e. when the inside seam has a tendency to open, the eccentricity is positive).
As can be seen from fig. 6:
N＝PH
and (3) obtaining a bending moment of the point A, and obtaining:
the fact can be calculated according to the above formulaLoad P applied to the boundaryHAnd PV。
2) Negative offset center-distance operating mode
In the test, PV、PHThe relationship with eccentricity can be determined according to fig. 7. The eccentricity e at the joint is defined as M/N (M, N is positive in the direction shown, i.e. negative when the outer seam has a tendency to open).
As can be seen from fig. 7:
N＝PH
and (3) obtaining a bending moment of the point A, and obtaining:
according to the formula, the actual loading P can be calculatedHAnd PV。
Fourth, load test
And aiming at the joint rotation rigidity test, horizontal loading is firstly carried out, and then vertical loading is carried out.
Aiming at the bending moment transfer test between rings, longitudinal loading is firstly carried out, then horizontal loading is carried out, and then vertical loading is carried out.
Before each working condition formal test, a small load (20% of the load of the working condition) needs to be applied to the structure firstly so that all parts are in good contact, then the load is unloaded, and then the formal load is started. In each working condition, the load is gradually applied in stages, and data acquisition can be carried out after the load is stable when one stage of load is added.
And (4) performing the next working condition test after the data acquisition is finished, and repeating the process, wherein if the test piece is damaged, the test is finished, as shown in fig. 8.
Fifth, test data acquisition
The data acquisition and processing system adopts MYJ-1 static digital resistance strain tester, a dataker intelligent programmable data acquisition unit, a corresponding test element and a computer to acquire and process data.
(1) Joint rotational stiffness test
In order to meet the test requirements, a series of changes of the tube sheet test piece are measured, observed and calculated in the process of the mechanical behavior test, and the method specifically comprises the following steps:
1) opening amount of joint (flare angle)
The joint opening (opening angle) is measured with an electrical displacement meter. As shown in fig. 9, 1 displacement meter 2 is respectively arranged at the side surface of the duct piece close to the inner cambered surface S and the outer cambered surface N; meanwhile, in order to compare the cores with each other, two displacement meters are respectively arranged at the corresponding positions of the inner cambered surface and the outer cambered surface of the duct piece.
2) Stress of joint bolt
Bolt stress was measured using strain gauges. The bolts need to be specially designed and processed (grooves are formed on two sides, strain gauges are attached to the grooves, and each bolt is provided with a stress measuring point).
3) Concrete strain at joint position and hand hole position
Concrete strain is measured by using a long gauge length resistance strain gauge. As shown in fig. 10, the strain gauges 3 are arranged to measure the distribution of the concrete strain at the joints and hand hole locations, particularly along the thickness of the duct piece.
4) Stress of steel bar
The stress of the steel bar is measured by a vibrating wire type steel bar meter. And before the duct piece is poured, welding the steel bar meter and the steel bar to be measured together at a preset position. As shown in fig. 11, the reinforcing bar meter 4 is arranged at the upper and lower rows of stressed main bars and hand hole reinforcing bars at the position of the duct piece close to the joint.
5) Pipe segment deformation (deflection)
The deflection of the duct piece is measured by an electrical measuring displacement meter 2. As shown in fig. 12(a), (b), the displacement meters 2 are arranged along the segment extrados.
In addition to directly measured parameters, observed and indirect quantities involved in the test include:
a) carrying out crack development;
b) a joint failure mode;
c) the rigidity of the joint (calculated according to the opening angle of the joint and the bending moment at the joint);
d) the joint bears the weight of the force.
(2) Bending moment transmission test between rings
According to the purpose and research content of the experiment, the parameters of the experiment test comprise:
1) opening amount of joint (flare angle)
The joint opening (opening angle) is measured with an electrical displacement meter. As shown in fig. 13, two displacement meters 2 are disposed on the side surface of the segment near the intrados and extrados, respectively.
2) Pipe segment deformation (deflection)
The deflection of the duct piece is measured by an electrical measuring displacement meter. As shown in fig. 13, two displacement meters 2 are arranged in common along the segment extrados.
3) Test piece section bending moment
The bending moment of the section of the test piece is measured by a long gauge length resistance strain gauge. As shown in fig. 13, a plurality of pairs of strain gauges 3 are arranged along the segment extrados.
Claims (6)
1. A method for testing the mechanical property of a pipe sheet joint is characterized by comprising the following steps: firstly, selecting a test piece, determining a joint of the test piece as a test object, determining a test loading mode, a displacement boundary condition and a loading working condition, then performing a rotational rigidity test and an inter-ring bending moment transmission test on the pipe piece joint, finally, acquiring test data, completing the rotational rigidity test and the inter-ring bending moment transmission test of the pipe piece joint, obtaining a stress mechanism, a bearing capacity and a rigidity change rule of the pipe piece joint under different loading working conditions, and obtaining key design parameters of the pipe piece joint.
2. The mechanical property test method of the segment joint according to claim 1, characterized in that: the 1:1 duct piece joint test piece is adopted, the form of the test piece is consistent with that of an actual duct piece, the test precision can be guaranteed, the repeatability is high, and the test cost is low.
3. The mechanical property test method of the segment joint according to claim 1, characterized in that: the loading mode and the displacement boundary condition of the segment joint are simplified, the rotational stiffness test of the segment joint is simplified into a vertical and horizontal bidirectional loading mode, the inter-ring bending moment transmission test is simplified into a vertical, horizontal and longitudinal three-way loading mode, and the displacement boundary condition is simplified in that one end of the displacement boundary condition is a fixed hinged support and the other end of the displacement boundary condition is a sliding hinged support.
4. The mechanical property test method of the segment joint according to claim 1, characterized in that: according to the difference of the internal water pressure of the tunnel and the difference of the assumed bending rigidity efficiency of the segment joint, the loading test working condition is set up in a grading mode, and then the working condition load is determined according to the eccentricity of the segment joint.
5. The mechanical property test method of the segment joint according to claim 4, characterized in that: and carrying out continuous loading tests on the test specimen under various working conditions according to the determined loading working conditions until the test specimen is damaged, so that the test investment is greatly reduced.
6. The mechanical property test method of the segment joint according to claim 1, characterized in that: and automatic measuring equipment is adopted to actually measure the opening amount of the segment joint, the bolt stress of the segment joint, the position of the segment joint, the concrete strain of the hand hole position, the stress of the steel bar and the deformation of the segment joint in the test process.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201911317188.1A CN111044370A (en) | 2019-12-19 | 2019-12-19 | Mechanical property test method for duct piece joint |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911317188.1A CN111044370A (en) | 2019-12-19 | 2019-12-19 | Mechanical property test method for duct piece joint |
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| CN111044370A true CN111044370A (en) | 2020-04-21 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111707511A (en) * | 2020-06-09 | 2020-09-25 | 同济大学 | Method for manufacturing preset crack tunnel segment for joint mechanical test |
| CN113374503A (en) * | 2021-07-29 | 2021-09-10 | 中铁隧道集团一处有限公司 | Method for embedding and arranging assembly type lining monitoring and measuring components |
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| US4213349A (en) * | 1976-11-22 | 1980-07-22 | Koryo Miura | Method of and apparatus for measuring stiffness |
| CN102004054A (en) * | 2010-09-21 | 2011-04-06 | 同济大学 | Three-way loading mechanical property test system of multifunctional lining segment joint |
| CN103953349A (en) * | 2014-04-24 | 2014-07-30 | 西南交通大学 | Test method for tunnel model with duct piece connectors with rigidity in controllable changes |
| CN103956109A (en) * | 2014-04-28 | 2014-07-30 | 西南交通大学 | Tunnel model test method with changeable rigidity of lining structure joint |
| CN109632470A (en) * | 2018-12-11 | 2019-04-16 | 上海市基础工程集团有限公司 | For section of jurisdiction plate connector mechanical property test device |
-
2019
- 2019-12-19 CN CN201911317188.1A patent/CN111044370A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4213349A (en) * | 1976-11-22 | 1980-07-22 | Koryo Miura | Method of and apparatus for measuring stiffness |
| CN102004054A (en) * | 2010-09-21 | 2011-04-06 | 同济大学 | Three-way loading mechanical property test system of multifunctional lining segment joint |
| CN103953349A (en) * | 2014-04-24 | 2014-07-30 | 西南交通大学 | Test method for tunnel model with duct piece connectors with rigidity in controllable changes |
| CN103956109A (en) * | 2014-04-28 | 2014-07-30 | 西南交通大学 | Tunnel model test method with changeable rigidity of lining structure joint |
| CN109632470A (en) * | 2018-12-11 | 2019-04-16 | 上海市基础工程集团有限公司 | For section of jurisdiction plate connector mechanical property test device |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111707511A (en) * | 2020-06-09 | 2020-09-25 | 同济大学 | Method for manufacturing preset crack tunnel segment for joint mechanical test |
| CN113374503A (en) * | 2021-07-29 | 2021-09-10 | 中铁隧道集团一处有限公司 | Method for embedding and arranging assembly type lining monitoring and measuring components |
| CN113374503B (en) * | 2021-07-29 | 2024-04-05 | 中铁隧道集团一处有限公司 | Method for embedding and arranging assembled lining monitoring and measuring components |
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Application publication date: 20200421 |