CN208520679U - Measure the combined type torsion shear apparatus and system of soil body shear wave velocity - Google Patents
Measure the combined type torsion shear apparatus and system of soil body shear wave velocity Download PDFInfo
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- CN208520679U CN208520679U CN201821105364.6U CN201821105364U CN208520679U CN 208520679 U CN208520679 U CN 208520679U CN 201821105364 U CN201821105364 U CN 201821105364U CN 208520679 U CN208520679 U CN 208520679U
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Abstract
The combined type torsion shear apparatus and system of soil body shear wave velocity are measured, from top to bottom successively includes constraint cover, live spindle and vibration unit；The vibration unit includes contact base plate and the piezo electric stack that is fixed in contact base plate；The lower end of live spindle is plugged in the center of contact base plate, and the upper end of live spindle is fixedly connected with constraint cover.The utility model is simple and reasonable, assembly is simple and convenient to operate, and has good promotional value in geotechnical engineering and monitoring structural health conditions field.
Description
Technical field
The utility model relates to soil mechanics Triaxial testers, system, especially a kind of in Large-scale Triaxial Experiments instrument
Measurement soil body shear wave velocity combined type torsion shear apparatus and system.
Background technique
Soil body shear wave velocity is very important mechanics parameter in geotechnical engineering design, Architectural site partition is divided,
Saturated sand liquefaction judgement, soil matrix shake, which fall into sedimentation and the quantization of Soil Anisotropic degree etc., to have great importance.Soil
The indoor test technology of body shear wave velocity specifically includes that resonant column method, flexure element method, supercritical ultrasonics technology etc..Wherein, flexure element method
Since its test philosophy is clear, method simple, intuitive, it has been used in a variety of earthwork test Instruments, wherein with triaxial tester
The most extensively.However, in Large-scale Triaxial Experiments sample compacting and condition of high ground stress loading procedure, the piezoelectric materials such as flexure element
It is highly vulnerable to breakage, flexure element fado is caused to be applied to fine grained soil and small-sized triaxial tester, existing three axis for installing flexure element additional are set
The standby maximum specimen size for being currently known support is 150mm × 300mm (diameter × height).Therefore, during the test, excite
The range of choice of frequency will receive stronger limitation, and then constrain the research of frequency dispersion problem.Flexure element need to be inserted into test soil sample
In, therefore there are certain disturbances to test soil sample, in addition, generally according to emitting voltage signal and being connect when using flexure element method
It receives voltage signal and calculates shear wave velocity, however, emitting voltage signal is specific ideal signal, itself can not reflect the spy of soil
Property, there are larger differences on attribute for reception signal and transmitting signal after earth propagation, and then to cross-correlation method true
Surely the application sheared in wave propagation time causes theoretic obstacle.
Utility model content
It can be used for that the structurally reasonable of Large-scale Triaxial Experiments instrument, assembly be simple, behaviour the purpose of the utility model is to provide a kind of
Make the combined type experimental rig and system for measuring soil body shear wave velocity that be convenient and can solve flexure element method there are various drawbacks.
The utility model solves technical solution used by prior art problem: the combined type of measurement soil body shear wave velocity is turned round
Shear test device from top to bottom successively includes constraint cover, live spindle and vibration unit；The vibration unit includes contact bottom
Plate and the piezo electric stack being fixed in contact base plate；The lower end of live spindle is plugged and fixed in the center of contact base plate, rotation master
The upper end of axis is fixedly connected with constraint cover.
The upper surface of the contact base plate is fixed with piezo electric stack protection block, offers in the side of piezo electric stack protection block
It is placed in slot, so that piezo electric stack is plugged and fixed in the merging slot.
The merging slot is set to the top of piezo electric stack protection block, and makes the interior of the open end direction constraint cover for being placed in slot
Side wall；It is provided with caging bolt hole on the side wall of the constraint cover, and makes the opening for being placed in slot described in the caging bolt hole face
End；The upper end of the piezo electric stack is fixed with protective cap, and is inserted into protective cap by piezo electric stack towards the caging bolt hole
It is placed in slot；The end of caging bolt is butted on protective cap by caging bolt hole, so that piezo electric stack, contact base plate and constraint
Cover is fixed on one.
The lower section of the constraint cover, which is equipped with, to match with the upper end of live spindle and the piezo electric stack protection block
Limiting slot, so that the upper end of the live spindle and the piezo electric stack protection block and constraint cover grafting, and pass through fixing piece
It is fixed together.
It is symmetrically arranged with two piezo electric stack protection blocks in the contact base plate, is symmetrically opened up in each piezo electric stack protection block
There are two being placed in slot, and the axis of the merging slot is made to be parallel to the upper surface of contact base plate.
The top surface edge of the contact base plate is chamfering structure, and contact base plate side wall is equipped with the draining through contact base plate
Through-hole.
The protective cap is hemispherical end cap.
The combined type torsion shear test system of soil body shear wave velocity is measured, including combined type torsion shear apparatus, signal occur
Device, power amplifier, charge amplifier, oscillograph and at least two acceleration transducers；The signal generator is put with power
Big device is connected, and the piezo electric stack in combined type torsion shear apparatus is connected with power amplifier；Acceleration transducer respectively with electricity
Lotus amplifier is connected, and charge amplifier is connected with oscillograph.
The utility model has the beneficial effects that: the utility model experimental rig using constraint cover, live spindle and
The fabricated structure of vibration unit, assembly is simple, and is convenient for the replacement of all parts；Pass through what is be arranged in vibration unit
Contact base plate and test soil sample carry out plane contact, avoid disturbance caused when flexure element Embedded test soil sample；Meanwhile it will
Piezo electric stack is placed in the inside of piezo electric stack protection block, contacts piezo electric stack directly with test soil sample, avoids piezoresistive material
Expect the problem of the destructible in Large-scale Triaxial Experiments sample compacting and condition of high ground stress loading procedure；The test system of the utility model
System can acquire vibration of the shearing wave after test soil sample is propagated during testing shear wave velocity by acceleration transducer
Dynamic signal, collected vibration signal attribute are closer to, are cut by method of characteristic point or cross-correlation method with can be convenient
Cut velocity of wave.The utility model is simple and reasonable, assembly is simple and convenient to operate, in geotechnical engineering and monitoring structural health conditions field
With good promotional value.
Detailed description of the invention
Fig. 1 is the structural schematic diagram before the experimental rig installation of the utility model.
Fig. 2 is the structural schematic diagram after the experimental rig installation of the utility model.
Fig. 3 is the structural schematic diagram of piezo electric stack protection block in the utility model.
Fig. 4 is the structural schematic diagram of piezo electric stack in the utility model.
Fig. 5 is the caging bolt of the experimental rig of the utility model and the structural relation schematic diagram of piezo electric stack.
Fig. 6 is the surface structure schematic diagram after the experimental rig installation of the utility model.
Fig. 7 is the attachment structure schematic diagram of the pilot system of the utility model.
Fig. 8 is the test grading curve of the test soil sample prepared.
Fig. 9 is the test result curve graph that the utility model determines shearing wave propagation time using method of characteristic point.
Figure 10 is the test result curve graph that the utility model determines shearing wave propagation time using cross-correlation method.
In figure: 1- constraint cover, 2- live spindle, 3- vibration unit, 4- piezo electric stack, 5- acceleration transducer, 6- connect
Bottom out plate, 7- piezo electric stack protection block, 8- test soil sample, 9- caging bolt hole, 10- triaxial tester, 11- signal generator,
12- power amplifier, 13- charge amplifier, 14- oscillograph, 1a- limiting slot, 4a- hemispherical end cap, 6a- drainage hole, 7a-
It is placed in slot, 9a- caging bolt, 10a- axial loading system.
Specific embodiment
The utility model is illustrated below in conjunction with the drawings and the specific embodiments:
It is forward and backward that Fig. 1 and Fig. 2 is that the combined type torsion shear apparatus of the measurement soil body shear wave velocity of the utility model is installed
Structural schematic diagram.The combined type torsion shear apparatus of soil body shear wave velocity is measured, from top to bottom successively includes constraint cover 1, rotation
Turn main shaft 2 and vibration unit 3；Vibration unit 3 uses Demountable: including contact base plate 6, being fixed in contact base plate 6
Piezo electric stack protection block 7 and the piezo electric stack 4 in piezo electric stack protection block 7；The lower end of live spindle 2 be plugged and fixed in
The upper end at the center of contact base plate 6, live spindle 2 is fixedly connected with constraint cover 1；Specifically, as shown in Figure 1: in containment shroud
The lower section of body 1 is equipped with the limiting slot 1a to match with the upper end of live spindle 2 and piezo electric stack protection block 7, so that rotation is led
The upper end of axis 2 and piezo electric stack protection block 7 and constraint 1 grafting of cover, and be fixed together by fixing pieces such as bolts.
As shown in Figs. 1-2, two piezo electric stack protections are preferably symmetrically fixed with by bolt in the upper surface of contact base plate 6
Block 7.Merging slot 7a is offered in the side of each piezo electric stack protection block 7, so that piezo electric stack 4 is plugged and fixed in the merging slot
In 7a, such structure design avoids piezo electric stack 4 and directly contacts with test soil sample 8, avoids piezoelectric material in large size three
The problem of destructible in shaft experiment sample compacting and condition of high ground stress loading procedure.
Further, Fig. 3 shows the specific structure of each piezo electric stack protection block 7: preferably putting into slot 7a and is set to pressure
The top of pile stack protection block 7 symmetrically opens up in each piezo electric stack protection block 7 there are two slot 7a is placed in, is placed in the axis of slot 7a
Line is parallel to the upper surface of contact base plate 6 and guarantees the open end of merging slot 7a towards the inner sidewall of constraint cover 1.Meanwhile such as
Shown in Fig. 1, it is provided with caging bolt hole 9 on the side wall of constraint cover 1, and makes opening for 9 face of caging bolt hole merging slot 7a
Mouth end；The upper end of piezo electric stack 4 can fix a hemispherical end cap 4a as protective cap (as shown in Figure 4) by epoxy resin, and
It is inserted into hemispherical end cap 4a piezo electric stack 4 in merging slot 7a towards caging bolt hole 9；Spiral shell will be limited using torque wrench
Bolt 9a is screwed by caging bolt hole 9, so that the end of caging bolt 9a is butted on hemispherical end cap 4a by caging bolt hole 9
(as shown in Figure 5) obtains the experimental rig of Fig. 6 so that piezo electric stack 4, contact base plate 6 and constraint cover 1 are fixed on one.Half
Spherical end cap 4a's is arranged in while providing protective effect for piezo electric stack 4 end and piezoelectricity but also in caging bolt 9a
It is more uniformly stressed when 4 abutting contact of storehouse.
The top surface edge of contact base plate 6 is chamfering structure, and 6 side wall of contact base plate is equipped with the draining through contact base plate 6
Through-hole 6a.As shown in Figure 1, it is preferred that drainage hole 6a is set at chamfering structure.
The combined type torsion shear test system for measuring soil body shear wave velocity, as shown in fig. 7, comprises combined type shown in Fig. 1-2
Torsion shear apparatus, signal generator 11, power amplifier 12, charge amplifier 13, oscillograph 14 and two acceleration sensings
Device 5；Signal generator 11 is connected with power amplifier 12, piezo electric stack 4 and power amplification in combined type torsion shear apparatus
Device 12 is connected；Two acceleration transducers 5 are connected with charge amplifier 13 respectively, and charge amplifier 13 is connected with oscillograph 14.
Wherein, signal generator 11 generates piezo electric stack 4 after power amplifier 12 for generating voltage pulse as excitation signal
Extensional vibration.Acceleration transducer 5 is for the vibration signal at the different elevation measuring points of collecting test soil sample 8 and by vibration signal
It is changed into electric signal, shows and be stored in simultaneously the propagation time calculating on oscillograph 14 for shearing wave after charge amplifier 13
Data are provided.In this course, live spindle 2 has extremely small rotation.The utility model uses the master of live spindle
Syllabus damps to reduce.
Shear wave velocity measurement is carried out using the combined type torsion shear test system of the measurement soil body shear wave velocity of the utility model
When, it can follow the steps below:
S1, system installation: by the conventional methods in " earthwork test rule " (SL237-1999) in large-scale three axis examination
Preparation test soil sample 8 on instrument 10 is tested, grading curve is as shown in Figure 8.By the upper of the constraint cover 1 of combined type torsion shear apparatus
Portion is connected with the axial loading system 10a of triaxial tester 10, and turns round the upper/lower terminal for testing soil sample 8 with combined type respectively
6 lower surface of contact base plate of shear test device and the pedestal of triaxial tester 10 fit closely, by combined type torsion shear test system
In two acceleration transducers 5 along vertical direction be separately fixed at test 8 side of soil sample different elevations at and two acceleration
The distance of degree sensor 5 is set as 0.351m, then in 80kPa etc. to consolidating 30min under confining pressure.
S2, determine shearing wave propagation time: enabling signal generator 11 generates voltage pulse as excitation signal, excitation letter
Number frequency be 2kHz.As shown in figure 5, being inputted at M, Q two in four piezo electric stacks 4 in combined type torsion shear apparatus
Voltage signal phase it is identical, at N, P two input voltage signal phase it is identical, at M, N (or P, Q) two input voltage signal
Opposite in phase, i.e. phase difference of pi.The voltage signal that signal generator 11 generates makes to be placed in vibration unit 3 after power amplifier 12
The piezo electric stack 4 in portion generates extensional vibration, so that the piezoelectricity while piezo electric stack 4 at M, Q two synchronizes elongation at N, P two
Storehouse 4 is synchronous to be shortened, and vice versa, and constraint cover 1 provides reaction force, under the collective effect of four piezo electric stacks 4, vibration
Unit 3 is whole to generate twisting vibration, and vibration is propagated in the form of turning round and cutting wave by test soil sample 8, and two of test 8 side of soil sample
Acceleration transducer 5 acquires vibration signal respectively and is transformed into electric signal, after charge amplifier 13 simultaneously display and
It is stored on oscillograph 14, according to record as a result, calculating separately shearing wave using method of characteristic point (peak-peak) and cross-correlation method
Propagation time Δ t, calculated result is shown in Fig. 9~Figure 10.Wherein, Fig. 9 is that shearing wave propagation time is determined using method of characteristic point
Test result curve graph.It is collected that its result illustrates two acceleration transducers 5 (being denoted as sensor-to go up, under sensor -)
The result in time domain of vibration signal, respectively according to first peak value of upper and lower two acceleration transducers 5 vibration signal collected
The point corresponding time difference can determine the propagation time；Figure 10 is the test knot that shearing wave propagation time is determined using cross-correlation method
Fruit curve graph.Show that upper and lower two acceleration transducers 5 (are denoted as sensor-to go up, under sensor -) the vibration letter of acquisition
Normalized Cross Correlation Function corresponding to number:Wherein, X (t) and Y (t) difference
For sensor-is upper, under sensor-in vibration signal collected within the t period, T is the testing time, and τ is upper and lower two acceleration
Spend the time difference of the vibration signal collected of sensor 5, CC/CCmaxThe maximum value corresponding time be the propagation time.Feature
Point method and the calculated result of cross-correlation method are closer to (shearing wave propagation time Δ t is respectively 1.522ms and 1.500ms).
S3, shear wave velocity calculate: according to L/ Δ t, wherein L=0.351m obtains method of characteristic point and cross-correlation method is calculated
Shear wave velocity be respectively 230.6m/s and 234.0m/s.
It, cannot the above content is specific optimal technical scheme further detailed description of the utility model is combined
Assert that the specific implementation of the utility model is only limited to these instructions.For the ordinary skill of the utility model technical field
For personnel, without departing from the concept of the premise utility, a number of simple deductions or replacements can also be made, should all regard
To belong to the protection scope of the utility model.
Claims (8)
1. measuring the combined type torsion shear apparatus of soil body shear wave velocity, which is characterized in that from top to bottom successively include containment shroud
Body, live spindle and vibration unit；The vibration unit includes contact base plate and the piezo electric stack that is fixed in contact base plate；Rotation
The lower end for turning main shaft is plugged and fixed in the center of contact base plate, and the upper end of live spindle is fixedly connected with constraint cover.
2. the combined type torsion shear apparatus of measurement soil body shear wave velocity according to claim 1, which is characterized in that described
The upper surface of contact base plate is fixed with piezo electric stack protection block, offers merging slot in the side of piezo electric stack protection block, so that
Piezo electric stack is plugged and fixed in the merging slot.
3. the combined type torsion shear apparatus of measurement soil body shear wave velocity according to claim 2, which is characterized in that described
It is placed in the top that slot is set to piezo electric stack protection block, and makes to be placed in the open end of slot towards the inner sidewall of constraint cover；Containment shroud
It is provided with caging bolt hole on the side wall of body, and makes the open end for being placed in slot described in the caging bolt hole face；The piezo electric stack
Upper end be fixed with protective cap, and make protective cap towards the caging bolt hole by piezo electric stack be inserted into merging slot in；Limit spiral shell
The end of bolt is butted on protective cap by caging bolt hole, so that piezo electric stack, contact base plate and constraint cover are fixed on one.
4. the combined type torsion shear apparatus of measurement soil body shear wave velocity according to claim 1 or 2, which is characterized in that
The lower section of the constraint cover is equipped with the limiting slot to match with the upper end of live spindle and the piezo electric stack protection block, with
Upper end and the piezo electric stack protection block and the constraint cover grafting for making the live spindle, and are fixed on one by fixing piece
It rises.
5. the combined type torsion shear apparatus of measurement soil body shear wave velocity according to claim 3, which is characterized in that described
Two piezo electric stack protection blocks are symmetrically arranged in contact base plate, symmetrically opened up in each piezo electric stack protection block there are two merging
Slot, and the axis of the merging slot is made to be parallel to the upper surface of contact base plate.
6. the combined type torsion shear apparatus of measurement soil body shear wave velocity according to claim 1, which is characterized in that described
The top surface edge of contact base plate is chamfering structure, and contact base plate side wall is equipped with the drainage hole through contact base plate.
7. the combined type torsion shear apparatus of measurement soil body shear wave velocity according to claim 3, which is characterized in that described
Protective cap is hemispherical end cap.
8. the pilot system of the combined type torsion shear apparatus using measurement soil body shear wave velocity described in claim 1, special
Sign is, including combined type torsion shear apparatus, signal generator, power amplifier, charge amplifier, oscillograph and at least two
A acceleration transducer；The signal generator is connected with power amplifier, the piezo electric stack in combined type torsion shear apparatus
It is connected with power amplifier；Acceleration transducer is connected with charge amplifier respectively, and charge amplifier is connected with oscillograph.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| 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 |
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