CN108982263B - Single-pile cyclic t-z model parameter measuring method - Google Patents
Single-pile cyclic t-z model parameter measuring method Download PDFInfo
- Publication number
- CN108982263B CN108982263B CN201810778084.XA CN201810778084A CN108982263B CN 108982263 B CN108982263 B CN 108982263B CN 201810778084 A CN201810778084 A CN 201810778084A CN 108982263 B CN108982263 B CN 108982263B
- Authority
- CN
- China
- Prior art keywords
- pile
- soil
- pile body
- box
- oil cylinder
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- 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
- G01N3/32—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces
- G01N3/36—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces generated by pneumatic or hydraulic means
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
Abstract
The invention discloses a single-pile circulation t-z model parameter measuring device based on soil deformation and shear band development, which comprises a rack, an experimental box, a hydraulic loading system, a PIV system and the like; the experimental box is used for containing soil bodies and is made of organic glass; the hydraulic loading system is arranged above the experimental box and has two functions: (1) the device is used for applying consolidation stress to the soil body so as to simulate different soil body stress states; (2) applying vertical cyclic load to the pile; the PIV system is used for observing the displacement field change of soil particles around the pile and the formation and development of a pile-soil interface shear band in the vertical cyclic loading process of the pile body. The device can realize the measurement of the side frictional resistance and the displacement of the pile body of the pile under the action of cyclic load, and accordingly obtain relevant mechanical parameters of a t-z model of the pile-soil action.
Description
Technical Field
The invention relates to a single-pile cyclic t-z model parameter measuring device based on soil deformation and shear zone development, which can measure the relation between load and displacement of a single pile under the cyclic action and obtain an important t-z model curve in engineering; meanwhile, by means of a PIV observation system, the law of deformation of soil around the pile and the development of the shear band can be obtained, and the mechanism of pile soil interface cycle weakening can be microscopically explained.
Background
When the pile bears the vertical load, the vertical resistance mainly comes from the side friction resistance of the pile and the soil and the pile end resistance, and the side friction resistance plays an important role for the long pile commonly used in the current engineering. The relation between the pile side resistance and the displacement is described by a t-z model proposed in the American API specification, and the method is widely applied to engineering design. At present, relevant scholars design an experimental device and an experimental method for testing and calibrating a t-z curve based on a direct shear unit experiment, but the method has the influence of a boundary effect, so that the actual exertion condition of the pile side frictional resistance cannot be accurately reflected.
In addition, the change rule and the internal mechanism of the side friction resistance of the pile under the vertical cyclic load need to be further researched. Generally, after the pile side is subjected to cyclic loading, soil in a certain range on the pile side can be locally sheared and gradually forms a shear band, the shear band determines the vertical bearing performance of the pile and determines the parameter value of a t-z model, but at present, the formation and development of the pile side shear band are less cognitive.
Disclosure of Invention
The invention aims to provide a device for measuring single-pile circulation t-z model parameters based on soil deformation and shear band development aiming at the defects of the prior art. The device is characterized in that: the relation between pile body lateral resistance and pile body vertical displacement on the one hand can be realized, and on the other hand can the monitoring of the soil body displacement field around the pile body when the pile body receives cyclic load.
The invention adopts the following technical scheme:
a single-pile circulation t-z model parameter measuring device based on soil deformation and shear zone development comprises a rack, a hydraulic loading system, an experiment box and a PIV system; the experimental box is an organic glass box for containing soil; the hydraulic loading system is arranged above the experiment box and used for applying initial soil pressure to simulate the stress state of a soil body and providing vertical cyclic load for the pile body to simulate the vertical cyclic load borne by the pile body in actual use; the PIV system is used for observing the change of the soil displacement field around the pile.
In the technical scheme, the frame comprises a base, a main reaction column, a main reaction beam, a secondary reaction column and a secondary reaction beam, wherein the main reaction column and the secondary reaction column are vertically fixed on the base; the pile body is a half pile formed by longitudinally splitting a conventional pile body along an axis, the section of the pile body is tightly attached to the inner wall of the experiment box and is driven into a soil body, the lower end of the pile body penetrates through the bottom of the experiment box and the base and is suspended, the lower part of the main oil cylinder is connected with the pile head loading end, an upper plate is placed on the soil body of the experiment box, and the lower end of the secondary oil cylinder is connected with the upper plate. The main oil cylinder is used for applying vertical circulating load to the pile body so as to simulate the load effect (vehicle load and the like) on the pile body in actual use. The secondary oil cylinder is used for applying pressure to soil in the box and is used for simulating the soil in different consolidation states.
The PIV system comprises a computer, a laser emitter, a synchronizer, a CCD camera and a scattering light column, wherein the computer controls the synchronizer to adjust a light source of the laser emitter, light is scattered by the scattering light column and uniformly projected on a soil body, the CCD camera shoots changes of soil particles around a pile of the whole pile body and feeds shooting information back to the computer.
And vaseline is smeared on all contact surfaces of the pile body and the experimental box.
The previous t-z observation device can not overcome the influence of end resistance, thereby causing larger error to the experimental result.
When the load was applyed to the master cylinder for t, the stake end displacement that corresponds this moment was z, and the shearing force size between the stake soil is tau, then has:
l, the length of the pile body after the suspension section is removed is m;
d: pile radius, in m.
The shearing force tau between the piles and the soil can be obtained according to the formula, and the soil body of the shearing zone meets Hooke's law, so that:
τ＝kz
wherein: k: the rigidity coefficient of the shear zone soil is kN/m3；
z: the displacement of the pile tip is in m.
The stiffness coefficient of the shear band soil under the action of cyclic loading can be obtained by the method.
The device can measure the pile side displacement and resistance of the pile under the action of the cyclic load, calibrate the t-z model parameters to obtain a t-z curve, and observe the deformation of the soil body on the pile side and the formation and development of the shear zone, explore the influence of the cyclic load on the rigidity coefficient of the soil body in the shear zone from the angle of the soil body deformation, and further disclose the action mechanism of the pile soil.
Drawings
FIG. 1 is a simplified model of a shear band;
FIG. 2 is a schematic diagram of the experimental box structure of the present invention (front view);
FIG. 3 is a schematic view of the overall structure of the present invention (left side view);
FIG. 4 is a schematic diagram (cross-sectional view) of the experimental box structure of the present invention;
FIG. 5 is a schematic diagram of a PIV apparatus;
FIG. 6 is a schematic diagram (top view) of the experimental box structure of the present invention;
FIG. 7 is a schematic view (top view) of the pile body of the present invention;
the device comprises a main reaction beam 1, a main oil cylinder 2, a main reaction column 3, a main reaction column 4, a soil body 5, a pile body 6, a ball 7, a base 7, an upper plate 8, a VDT 9, L, a VDT 10, a VDT L fixing device 11, an axial force meter 11, a secondary reaction beam 12, a secondary oil cylinder 13, an axial force meter 14, a secondary reaction column 15, a CCD camera 16, a camera support 17, a synchronizer 18, a laser emitter 19, a light scattering column support 20 and a light scattering column 21.
Detailed Description
Referring to fig. 2-7, the device for measuring the single-pile circulation t-z model parameters based on soil deformation and shear band development comprises a frame, a hydraulic loading system, an experiment box and a PIV system; the frame comprises a base 7, a main reaction column 3, a main reaction beam 1, a secondary reaction column 15 and a secondary reaction beam 12, wherein the main reaction column 3 and the secondary reaction column 15 are both vertically fixed on the base 7, the main reaction beam 1 is erected and fixed on the main reaction column 3, the secondary reaction beam 12 is erected and fixed on the secondary reaction column 15, the experimental box is an organic glass box for containing soil and is fixed on the base, and an upper plate is placed above the soil; the pile body 5 is a half pile formed by longitudinally splitting a conventional pile body along an axis, the section of the pile body is tightly attached to the inner wall of the experiment box and is driven into a soil body, the lower end of the pile body penetrates through the bottom of the experiment box and the base and is suspended, the bottom of the pile body and the bottom of the experiment box can be provided with a ball 6 hydraulic loading system which comprises a main oil cylinder 2 and a secondary oil cylinder 13 which are fixedly arranged below the main counter-force beam 1 and the secondary counter-force beam 12 respectively, the main oil cylinder is connected with a pile head loading end and used for loading vertical cyclic load to the pile body, and the secondary oil cylinder is connected with the upper plate and used for applying pressure to the soil. The PIV system is used for observing the change of a soil displacement field around a pile, and comprises a computer, a laser emitter 19, a synchronizer 18, a CCD camera 16 and a scattering light column 21, wherein the computer controls the synchronizer 18 to adjust a light source of the laser emitter 19, light is scattered by the scattering light column 21 and uniformly hits on a soil body, the CCD camera 16 shoots the change of soil particles around the pile of the whole pile body, and shooting information is fed back to the computer.
All contact surfaces of the pile body and the experimental box are coated with vaseline, and in addition, a ball can be embedded into a contact part of the bottom of the experimental box and the pile body so as to reduce the influence of frictional resistance on the experiment as much as possible.
In addition, the observation device can also comprise software and a data acquisition system, such as a computer, a data acquisition instrument and the like, wherein the data acquisition instrument is connected with each sensor for data acquisition, and the computer analyzes and processes the data and issues an instruction according to user setting.
The test process using the device of the invention is briefly described below by taking a sand sample as an example:
when the loading device works, the servo loading system is disassembled, vaseline is smeared on one smooth side of the pile, the pile is placed in the glass box, the central axis of the pile is aligned with the scribed line on the glass box, the lower end of the pile penetrates through the hole in the bottom of the experiment box, the pile is manually fixed, sandy soil is added into the glass box, the pile is fixed by the sandy soil at the moment, and the upper plate is placed on the sandy soil. And installing a servo loading system, applying consolidation load and enabling the soil body to be deformed stably.
②, the PIV system is started to realize the real-time monitoring of the displacement field of soil particles around the pile when the pile is subjected to cyclic load.
③ the servo motor controls the main oil cylinder to apply vertical cyclic load to the pile, the L VDT can be used to obtain the displacement of the pile body, the oil cylinder can be used to read the lateral friction of the pile, and the t-z curve can be obtained.
After the test, the test box was carefully cleaned and prepared for the next set of tests.
Claims (3)
1. A single-pile circulation t-z model parameter measurement method based on soil deformation and shear zone development is characterized in that the method is realized based on a device which comprises a rack, a hydraulic loading system, an experiment box and a PIV system; the experimental box is an organic glass box for containing soil; the hydraulic loading system is arranged above the experiment box and used for applying initial soil pressure to simulate the stress state of a soil body and providing vertical cyclic load for the pile body to simulate the vertical cyclic load borne by the pile body in actual use; the PIV system is used for observing the change of the soil displacement field around the pile; the hydraulic loading system comprises a main oil cylinder (2) and a secondary oil cylinder (13) which are fixedly arranged below the main reaction beam (1) and the secondary reaction beam (12) respectively; the pile body (5) is a half pile formed by longitudinally splitting a conventional pile body along an axis, the section of the pile body is tightly attached to the inner wall of the experiment box and is driven into a soil body, the lower end of the pile body penetrates through the bottom of the experiment box and the base and is suspended, the lower part of the main oil cylinder is connected with the pile head loading end, an upper plate (8) is placed on the soil body (4) of the experiment box, and the lower end of the secondary oil cylinder is connected with the upper plate;
the method comprises the following steps:
when the load was applyed to the master cylinder for t, the stake end displacement that corresponds this moment was z, and the shearing force size between the stake soil is tau, then has:
l, the length of the pile body after the suspension section is removed is m;
d: pile radius, in m;
the shearing force tau between the piles and the soil can be obtained according to the formula, and the soil body of the shearing zone meets Hooke's law, so that:
τ＝kz
wherein: k: the rigidity coefficient of the shear zone soil is kN/m3；
z: displacement of the pile tip in m;
the stiffness coefficient of the shear band soil under the action of cyclic loading can be obtained by the method.
2. The single pile cycle t-z model parameter measurement method based on soil deformation and shear band development as claimed in claim 1, wherein the PIV system comprises a computer, a laser emitter (19), a synchronizer (18), a CCD camera (16) and a scattered light column (21), the synchronizer (18) is controlled by the computer to adjust the light source of the laser emitter (19), light is scattered by the scattered light column (21) and uniformly hits on the soil, the CCD camera (16) shoots the change of soil particles around the pile of the whole pile body and feeds the shot information back to the computer.
3. The method for measuring the parameters of the single-pile circulation t-z model based on the soil deformation and the shear zone development as claimed in claim 1, wherein vaseline is smeared on all contact surfaces of the pile body and the experimental box.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810778084.XA CN108982263B (en) | 2018-07-16 | 2018-07-16 | Single-pile cyclic t-z model parameter measuring method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810778084.XA CN108982263B (en) | 2018-07-16 | 2018-07-16 | Single-pile cyclic t-z model parameter measuring method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108982263A CN108982263A (en) | 2018-12-11 |
| CN108982263B true CN108982263B (en) | 2020-08-04 |
Family
ID=64548674
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810778084.XA Active CN108982263B (en) | 2018-07-16 | 2018-07-16 | Single-pile cyclic t-z model parameter measuring method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108982263B (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109868849B (en) * | 2019-01-28 | 2020-07-07 | 重庆大学 | Pile-soil interaction visual test device and test method thereof |
| CN110376063B (en) * | 2019-07-22 | 2020-06-02 | 山东华鉴工程检测有限公司 | Testing device and method for measuring displacement field of soil body around loaded structure |
| CN111307857A (en) * | 2019-11-21 | 2020-06-19 | 江苏亚特尔地源科技股份有限公司 | Visual energy pile model test system and non-contact measurement method thereof |
| CN111829894B (en) * | 2020-06-24 | 2022-02-08 | 山东大学 | Rock-soil multi-field measurement test system and method |
| CN114739353B (en) * | 2022-03-07 | 2023-10-27 | 浙江理工大学 | Pile-soil interaction visual anti-interference experimental device and experimental method |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU1352315A1 (en) * | 1986-04-24 | 1987-11-15 | Московский Инженерно-Строительный Институт Им.В.В.Куйбышева | Device for investigating dynamic properties of grounds |
| CN102628767B (en) * | 2012-03-23 | 2014-01-22 | 河海大学 | Device and method for testing mechanical properties of pile-soil contact surface |
| CN103217348B (en) * | 2013-04-12 | 2016-01-20 | 同济大学 | Simulate the test unit of soil-aggregate subgrade mechanical behavior under reciprocal traffic traveling load |
| RO130870B1 (en) * | 2014-06-20 | 2019-12-30 | Universitatea Tehnică "Gheorghe Asachi" Din Iaşi | Apparatus for determining mechanical characteristics |
| CN105910920A (en) * | 2016-06-22 | 2016-08-31 | 青岛理工大学 | Temperature control pile-soil interface direct shear test device |
| CN106988352B (en) * | 2017-04-28 | 2020-11-17 | 浙江科技学院 | Testing method for horizontal bearing capacity of single pile under consideration of soil body pre-consolidation and cyclic load |
| CN207379851U (en) * | 2017-11-11 | 2018-05-18 | 广州环保投资集团有限公司 | Cyclic load load testing machine based on transparent soil model |
| CN108037022A (en) * | 2017-12-19 | 2018-05-15 | 浙江大学 | A kind of stake Soil Interface shearing test device and test method based on picture catching |
-
2018
- 2018-07-16 CN CN201810778084.XA patent/CN108982263B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN108982263A (en) | 2018-12-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN108982263B (en) | Single-pile cyclic t-z model parameter measuring method | |
| CN109342189B (en) | Tension-torsion combined multi-axis fracture experiment system and experiment method | |
| CN108982264B (en) | P-y curve measuring device based on soil body shear band development | |
| CN107238457A (en) | A kind of low thrust measurement apparatus | |
| CN106525577A (en) | Device and method for testing dynamic mechanical properties of materials under tensile/shear combined loading | |
| CN206095789U (en) | Unipolar tensile strength survey device of full -automatic horizontal soil | |
| CN106092756A (en) | A kind of hollow ring shear apparatus applying confined pressure | |
| CN103913380A (en) | All-in-one machine for testing soil engineering tension-compression strength | |
| CN108982265B (en) | Experimental device for pile soil shearing action is observed and is measured based on PIV technique | |
| CN108444816B (en) | Rock mass structural plane cyclic shear tester and test method | |
| CN105716956A (en) | Creep test device and control system thereof | |
| CN201331403Y (en) | Moment rigidity tester for hub bearing unit | |
| CN102053040B (en) | Dynamic bearing ratio detecting method and instrument | |
| CN107843553A (en) | A kind of coal body and Anchor Agent interface binding intensity method of testing | |
| CN103278445B (en) | Positive extrusion test method for plastic forming friction coefficient and friction factor | |
| CN209727611U (en) | Pulse moves rock fracture under hydraulic pressure and responds visual Simulation experimental system | |
| CN110018056A (en) | A kind of sandstone reservoir wellbore stability evaluation experimental device and method | |
| Tehrani et al. | Laboratory study of the effect of pile surface roughness on the response of soil and non-displacement piles | |
| CN109653262A (en) | A kind of multilayer sleeve opening pile can be used for measuring a resistance and the internal soil plug of assessment | |
| CN212110919U (en) | Concrete axle draws testing arrangement | |
| CN108716892A (en) | A kind of cylindrical roller deformation device and its measurement method with optical measurement | |
| CN109374441B (en) | Multifunctional ring shear apparatus testing device based on TSZ full-automatic testing machine and use method thereof | |
| CN207623143U (en) | The intelligent experimental rig that a kind of detection soil body horizontal direction tension is split | |
| CN110044738A (en) | The fatigue experimental device and its application method that weld seam Multiaxial stress controllably applies | |
| DE102017123275A1 (en) | Method and apparatus for dynamic load testing |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |