CN1458523A - New technological method-2 for detecting shear wave speed in geotechnical static and dynamic triaxial instrument - Google Patents
New technological method-2 for detecting shear wave speed in geotechnical static and dynamic triaxial instrument Download PDFInfo
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- CN1458523A CN1458523A CN 03129928 CN03129928A CN1458523A CN 1458523 A CN1458523 A CN 1458523A CN 03129928 CN03129928 CN 03129928 CN 03129928 A CN03129928 A CN 03129928A CN 1458523 A CN1458523 A CN 1458523A
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Abstract
Front and back cover plates and a pair of composite piezoelectrical ceramic rods are fixed into one integral and set inside a casing to constitute the sensor and connected hermetically via O-ring and casing. The front cover plate is one stepped cylinder with two fanned columns in the top, and the circular back cover plate has also two fanned columns in the diagonal line positions. Each of the composite piezoelectrical ceramic rods is constituted by several laminated PZT rings in parallel connection, and is sandwiched between the fanned columns of the front and the back cover plates. When two composite piezoelectrical ceramic rods stretch and withdraw simultaneously, one torque is formed in the front and the back cover plates to produce torsion vibration. The present invention has the advantages of low operation frequency, small volume and great radiation energy of the sensor, is suitable for shear wave speed in various soil sample, and can inhibit longitudinal wave interference and distinguish the first arrival time of shear wave.
Description
Technical field
The present invention relates to a kind of Geotechnical Engineering measuring technology.
Background technology
In Geotechnical Engineering, the shear wave velocity of soil layer is an important soil nature parameter, has obtained the attention of height and application widely.Bending unit method commonly used is carried out the test of shear wave velocity at present quiet the geotechnique, the dynamic triaxial apparatus.There is following shortcoming in this method: 1. bending unit need insert the certain degree of depth of test specimen (being generally 3mm), thereby cause disturbance certain in the insertion depth scope, also cause simultaneously the uncertainty of shearing wave spread length, the error that only this item causes can reach 16%; 2. the interference of near-field effect and stray wave makes the initial time of shearing wave have bigger subjectivity, and the measuring error of bringing thus can reach 30%; What 3. bending unit produced is a kind of polarized wave, and the sensitive direction that must will transmit and receive the unit during test is arranged unanimity, could effectively receive test signal; 4. because flexure element needs often to insert in the soil, and insulation and waterproof problem are more difficult, this has also limited the serviceable life of this device.In addition, the plain edition shearing wave sensor that adopts in ultrasonic engineering generally is to utilize single-sheet thickness shear type PZT wafer to make.There is following problem indoor in such sensor when carrying out the measurement of soil sample shear wave velocity: 1. thickness shear is a kind of dither pattern (being used to make the wafer vibration frequency of sensor thickness shear-vibration pattern usually greater than 400kHz), electromechanical coupling factor is lower, the sensor emittance is little, and the shearing wave propagation distance is very short; 2. the characteristic impedance of PZT wafer is much larger than the characteristic impedance of soil sample, and this makes and be difficult to coupling between the two, thereby has further reduced to enter the shearing wave energy of the soil body; 3. can't suppress compressional wave disturbs, especially for medium as clay, the high loss of this class of saturated loosening sand, compressional wave disturbs very serious, and this makes this method only be fit to the shear wave velocity of test dry sand, and needs to cooperate filtering technique to discern skill mutually with certain shaking.Therefore, almost can't in dynamic and static triaxial test, utilize this class sensor.
Summary of the invention
The purpose of this invention is to provide a kind of simple in structure, frequency of operation is low (5kHz-30kHz), the scissoring vibration emittance is big and can match with various quiet, moving triaxial shear equipments and test the new technology of shear wave velocity, thereby overcome bending unit method and the existing shortcoming of plain edition shear wave velocity sensor.
Specifying shown in accompanying drawing 1～accompanying drawing 3 of, dynamic triaxial apparatus build-in test shear wave velocity novel technical method-2 quiet the geotechnique.Adopt front shroud (1), back shroud (2), piezoelectric composite ceramics rod that sensor is formed in (3) and shell (4).Wherein, front shroud (1) is that ladder is cylindrical, and cover plate top diagonal bits is equipped with two fan-shaped cylinders (13), and the size of front shroud (1) and back shroud (2) is according to the ceramic rod that adopts (3) being mated.Back shroud (2) is circular, at the diagonal position of one side two fan-shaped cylinders is arranged also, and with erection bolt (5) front shroud (1), piezoelectric composite ceramics rod being fastened as one to place in the shell (4) to (3) and back shroud (2) becomes the shear wave velocity sensor.Outer at front shroud (1) top is provided with semi-circular recesses, by O RunddichtringO (11) in the groove and shell (4) seal combination.Cable fairlead (12) and drainage path (8) are set in the inside of front shroud (1).The piezoelectric composite ceramics rod is made up of two piezoelectric composite ceramics rods (3).The piezoelectric composite ceramics rod is by superimposed composition of several pieces PZT piezoelectric ceramics annulus of thickness vibration mode, the two sides of every piezoelectric ceramics annulus is silver-plated, mode according to parallel connection connects and composes the piezoelectric composite ceramics rod then, and two piezoelectric composite ceramics rods of same connected mode are formed the piezoelectric composite ceramics rod to (3).The piezoelectric composite ceramics rod is clipped between the fan-shaped cylinder of front and rear cover plate (1,2) (3).When two piezoelectric composite ceramics rods are flexible simultaneously, just front shroud (1) formed moment of torsion, thereby produce twisting vibration.The piezoelectric composite ceramics rod is fixed in front shroud (1) outside to two electrode cables (7) of (3) by cable fairlead (12) and pinout connector (6).Top at upper case (4) is provided with semi-circular recesses, so that cooperate with three afterburning equipment, lower case (4) bottom is established a base fixed orifice (9) and fixed with the set bolt (10) and the base of triaxial apparatus.Pinout connector (6) adopts the mode of internal and external casing, and outer tube and shell (4) are fixing, and the extruding inner sleeve makes the O-ring seal distortion and its cable (7) is sealed.
Description of drawings
Fig. 1 is each component-assembled figure of the present invention.1-front shroud wherein; The 2-back shroud; 3-piezoelectric composite ceramics rod is right; The 4-shell; The 5-erection bolt; The 6-pinout connector; The 7-electrode cable; The 8-drainage path; 9-base fixed orifice; The 10-set bolt; The 11-O RunddichtringO; 12-cable fairlead.
Fig. 2 is the connection diagram of piezoelectric composite ceramics bar structure and electrode.
Fig. 3 is the three-dimensional effect diagram of forward and backward covering plate structure.13-fan-shaped cylinder wherein; The 14-bolt hole.
Fig. 4 carries out the embodiment Experimental equipment of shear wave velocity measurement in quiet, dynamic triaxial apparatus for the present invention.15-triaxial cell wherein, 16-is two shear wave velocity sensors up and down, 17-soil sample test specimen, 18-latex film, 19-sound wave emissions receiving instrument, 20-draining valve, 21-triaxial apparatus gusset, 7-electrode cable.
Specific embodiment
With reference to accompanying drawing 1～4.Wherein front shroud (1) adopts the hard metal of lightweight, and back shroud (2) adopts heavy metals such as stainless steel or copper, and the diameter of forward and backward cover plate is φ 39.1mm, and the diameter phi 70mm of shell (4), upper sensor height are 50mm, and lower sensor is 70mm.At first the electrode of piezoelectric composite ceramics rod to (3) connected, cable (7) is stretched out the outside of front shroud (1) by cable fairlead (12).Using erection bolt (5) to pass the piezoelectric composite ceramics rod then is fixed together front and rear cover plate to the bolt hole (14) of (3) and fan-shaped cylinder.In the groove of front shroud (1), put O type circle, front shroud, back shroud, piezoelectric composite ceramics rod are opposite in the shell (4).At last outgoing cable (7) being passed cable draws joint (6) fixing seal finish assembling on front shroud.
Sensor (16) is positioned in the triaxial cell (15), and the device of composition dynamic triaxial apparatus build-in test shear wave velocity as shown in Figure 4.During test, the soil sample test specimen (17) of φ 39.1mm * 80mm is put latex film (18) be positioned between the lower sensor.Pressurization in the pressure chamber, draining valve (20) about opening on the rows of sensors water lines carries out discharging consolidation, through behind the official hour, with sensor emission one alternate electrical signal of sound wave emissions receiving instrument (19) to top or bottom, make sensor emission Jian Qiebo, Jian Qiebo is by behind the soil sample test specimen, received and become the electric charge of alternation, this electric signal to amplify through sound wave emissions receiving instrument (19) the shearing wave conversion of signals by the sensor of the other end to receive.Being recorded from being transmitted into the time interval of reception by the sound wave emissions receiving instrument, promptly is the time of shearing wave by soil sample, and the length of test specimen is known, and then the shear wave velocity of soil sample can be determined.
Beneficial effect of the present invention is: the piezoelectric ceramics annulus with thickness vibration mode forms the piezoelectric composite ceramics rod, and Further composition piezoelectric composite ceramics rod is opposite to and makes the shear wave velocity sensor in the same sensor. This sensor has and shakes The advantages such as dynamic frequency is low, volume is little, emittance is big, penetration thickness is big and the shearing wave waveform is pure, antijamming capability is strong. Be specially adapted to test the shear wave velocity of weak soil and saturated sand soil sample. For test diameter 3.91cm sample sensing The vibration frequency of device can be accomplished 10kHz, can greatly improve the measuring distance of shear wave velocity, need not consider emission during measurement Relative angle between sensor and the receiving sensor. Owing to adopt the torsional shear vibration mode, establishment compressional wave do Disturb, can identify very easily the first arrival time of shearing wave. Its sealing device can be normal in the water of 1Mpa pressure Work, and seepage does not take place, and also dismounting is easy to maintenance, and cost of manufacture is cheap. The present invention easily with existing various quiet, Moving triaxial shear equipment matches, and forms shear wave velocity and quiet, moving three axles shearing joint test equipment, thereby forms a kind of new The geotechnological joint test device of type.
Claims (2)
1. quiet the geotechnique, the novel technical method-2 of dynamic triaxial apparatus build-in test shear wave velocity, it is characterized in that adopting front shroud (1), back shroud (2), the piezoelectric composite ceramics rod is formed sensor to (3) and shell (4), wherein, front shroud (1) is that ladder is cylindrical, cover plate top diagonal bits is equipped with two fan-shaped cylinders (13), its size is according to the ceramic rod that adopts (3) being mated, back shroud (2) is circular, diagonal position in one side also has two fan-shaped cylinders, with erection bolt (5) with front shroud (1), the piezoelectric composite ceramics rod fastens as one to (3) and back shroud (2) and places in the shell (4), by O RunddichtringO (11) in the semi-circular recesses of front shroud (1) outer, top and shell (4) seal combination, cable fairlead (12) and drainage path (8) are set in the inside of front shroud (1), the piezoelectric composite ceramics rod is made up of two piezoelectric composite ceramics rods (3), the piezoelectric composite ceramics rod is clipped in front and rear cover plate (1 to (3), 2) between the fan-shaped cylinder, the piezoelectric composite ceramics rod is fixed in front shroud (1) to two electrode cables (7) of (3) by cable fairlead (12) and pinout connector (6).
2. according to the novel technical method-2 of described, the dynamic triaxial apparatus build-in test shear wave velocity quiet of claim 1 the geotechnique, it is characterized in that in several pieces PZT piezoelectric ceramics annulus superimposed form of described piezoelectric composite ceramics rod by thickness vibration mode, the two sides of every piezoelectric ceramics annulus is silver-plated, mode according to parallel connection connects and composes the piezoelectric composite ceramics rod then, and two piezoelectric composite ceramics rods of same connected mode are formed the piezoelectric composite ceramics rod to (3).
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 03129928 CN1204401C (en) | 2003-05-23 | 2003-05-23 | New technological method-2 for detecting shear wave speed in geotechnical static and dynamic triaxial instrument |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 03129928 CN1204401C (en) | 2003-05-23 | 2003-05-23 | New technological method-2 for detecting shear wave speed in geotechnical static and dynamic triaxial instrument |
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| Publication Number | Publication Date |
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| CN1458523A true CN1458523A (en) | 2003-11-26 |
| CN1204401C CN1204401C (en) | 2005-06-01 |
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| CN 03129928 Expired - Fee Related CN1204401C (en) | 2003-05-23 | 2003-05-23 | New technological method-2 for detecting shear wave speed in geotechnical static and dynamic triaxial instrument |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101520340B (en) * | 2009-03-27 | 2010-07-28 | 中国民航大学 | Penetration soil layer original position elastic wave testing device |
| CN105388219A (en) * | 2015-10-26 | 2016-03-09 | 东南大学 | Piezoelectric ring excitation device for testing granular material shear wave velocity and indoor testing device |
| CN108398180A (en) * | 2018-03-21 | 2018-08-14 | 大连理工大学 | A kind of experimental rig, system and test method measuring coarse-grained soil shear wave velocity |
| CN108663265A (en) * | 2018-07-12 | 2018-10-16 | 大连理工大学 | Measure combined type torsion shear apparatus, the system and method for soil body shear wave velocity |
| CN109187168A (en) * | 2018-10-25 | 2019-01-11 | 南京工业大学 | A kind of stabilization and accurate temperature controlled anisotropy Resonant Column system and method |
| CN112630416A (en) * | 2020-12-07 | 2021-04-09 | 温州大学 | Test device for simulating power generation performance of piezoelectric device under different vehicle loads based on triaxial apparatus |
-
2003
- 2003-05-23 CN CN 03129928 patent/CN1204401C/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101520340B (en) * | 2009-03-27 | 2010-07-28 | 中国民航大学 | Penetration soil layer original position elastic wave testing device |
| CN105388219A (en) * | 2015-10-26 | 2016-03-09 | 东南大学 | Piezoelectric ring excitation device for testing granular material shear wave velocity and indoor testing device |
| CN108398180A (en) * | 2018-03-21 | 2018-08-14 | 大连理工大学 | A kind of experimental rig, system and test method measuring coarse-grained soil shear wave velocity |
| CN108398180B (en) * | 2018-03-21 | 2023-04-18 | 大连理工大学 | Test device, system and test method for measuring shear wave velocity of coarse-grained soil |
| CN108663265A (en) * | 2018-07-12 | 2018-10-16 | 大连理工大学 | Measure combined type torsion shear apparatus, the system and method for soil body shear wave velocity |
| CN109187168A (en) * | 2018-10-25 | 2019-01-11 | 南京工业大学 | A kind of stabilization and accurate temperature controlled anisotropy Resonant Column system and method |
| CN112630416A (en) * | 2020-12-07 | 2021-04-09 | 温州大学 | Test device for simulating power generation performance of piezoelectric device under different vehicle loads based on triaxial apparatus |
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| Publication number | Publication date |
|---|---|
| CN1204401C (en) | 2005-06-01 |
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