CN102706728A - Multifunctional unsaturated soil triaxial test device capable of circularly applying suction and method thereof - Google Patents

Abstract

The invention discloses a multifunctional unsaturated soil triaxial test device capable of circularly applying suction and a method of the device, relating to the field of soil tests. The test device is an improvement of the conventional saturated soil triaxial test device, a confining pressure unit, an axial force applying unit and an axial displacement measuring unit are kept, and a suction applying unit, a temperature control unit, two pressure chambers, a differential pressure transducer, a reference tube and a data acquisition unit are provided. The test method comprises the following steps: at first, placing a saturated remolded soil sample or an undisturbed soil sample into a triaxial pressure chamber, and applying the suction in the pressure chamber so as to enter into an unsaturated stage; and then carrying out a shear test on the unsaturated soil by applying confining pressure so as to obtain deformation curves under different suctions and confining pressures and intensity parameters of the unsaturated soil. The multifunctional unsaturated soil triaxial test device capable of circularly applying the suction and the method are suitable for moisture removal and absorption, solidification, un-drained shear and drained shear tests of the unsaturated soil under different temperatures, and the intensity tests under different hydraulic powder paths are realized.

Description

Multi-functional circulation applies the unsaturated soil triaxial test devices and methods therefor of suction

Technical field

The present invention relates to the soil test field, relate in particular to the unsaturated soil triaxial test devices and methods therefor that a kind of multi-functional circulation applies suction.

Background technology

In vast arid and semi-arid lands, major part all is a unsaturated soil; And a large amount of geologic hazards is relevant with unsaturated soil.Because the experimental technique and the theoretical level of unsaturated soil can not show a candle to the saturated soil maturation,, analyze this type of problem at present and normally adopt saturated soil theoretical in order to simplify.Along with the researchist is more and more deep to the understanding of unsaturated soil, adopt this type of problem of the theoretical solution of unsaturated soil more reasonable.The essential distinction of unsaturated soil and saturated soil is that saturated soil has the stress history dependence, and unsaturated soil is not only relevant with stress history, and relevant with hydraulics history.Different with saturated soil, unsaturated soil is the three-phase porous medium, comprises solid phase, gas phase and liquid phase.Because the existence of gas phase, the pore water pressure in the unsaturated soil are normally born.

Because unsaturated soil Duo gas phase than saturated soil, more than therefore stress variable, i.e. a suction.Suction is that the surface and the interior liquid and gas of hole of inside soil body solid phase interact and generation, and the strength and stiffness of the soil body are increased.Therefore the theory of saturated soil and experimental technique are also inapplicable, have often underestimated the safety coefficient of the soil body.Simultaneously, owing to there is the effect of capillary hysteresis, for same matric suction, the intensity of passing through dehumidification and the moisture absorption soil body afterwards respectively is also inequality, also relevant with saturation degree, and relevant with drying and watering cycle history.

When the unsaturated soil disaster problem on landslide and so on was brought out in the analysis rainfall, the intensity index of the soil body was one of most important parameter.And these parameters are relevant with suction, so suction is to need the problem that will solve badly to the contribution of intensity.The face of land cracking that the evaporation relevant with unsaturated soil simultaneously causes and the pollutants transfer and the temperature of refuse landfill have substantial connection; The native water state of unsaturated soil is also relevant with temperature, and there be limited evidence currently of has research to relate to the mechanics and the hydraulics character of unsaturated soil under the test different temperatures.Different native water states can cause different intensive parameters, therefore when this type of unsaturated soil problem of analysis, are necessary to study Influence of Temperature.Opposite with unsaturated soil, the measuring accuracy of the indoor triaxial test of saturated soil and controllability have obtained generally acknowledging of domestic and international rock-soil mechanics field.

To the testing equipment of unsaturated soil, domestic and international research personnel have carried out a large amount of research at present.To unsaturation soil suction control technology, major part realizes through axle translation technology.The axle translation be with the hole press to increase on the occasion of, also increase air pressure simultaneously, apply the matric suction of setting through the two difference.But when being generalized to presence states, the hole in the unsaturated soil is pressed and is all born, and this technology is just no longer suitable.No longer need apply atmospheric pressure, during the negative hole pressure condition of true reappearance soil sample at the scene the time, can apply suction is a difficult problem in the unsaturated soil research.And existing method is the soil sample bottom discharge, or soil sample top and bottom draining together, and equilibration time is very long, and degree of accuracy is not high.The test unit of studying test unsaturated soil behavior under different temperatures simultaneously neither be a lot.

Summary of the invention

The object of the invention just is that overcoming prior art exists shortcoming and defect, the unsaturated soil triaxial test devices and methods therefor that provides a kind of multi-functional circulation to apply suction.

This test unit is simple in structure, and is easy to use, can accurately reflect the mechanics and the hydraulics character of unsaturated soil under the different temperatures.

This test method mainly is to adopt dialysis to reach needed suction, and the negative hole in the soil sample is pressed and approached on-the-spot virtual condition, and combines temperature control unit to carry out the test under the different temperatures.Take off moisture absorption around adopting soil sample, shortened the unsaturated soil balance time.

The objective of the invention is to realize like this:

This test unit is the improvement to existing " saturated soil triaxial test equipment "; Keep wherein confined pressure unit, axle power applying unit and axial displacement measuring unit, be provided with suction applying unit, temperature control unit, two pressure chamber, differential pressure pick-up, reference pipe and data acquisition unit.

This test method is: earlier saturated remoulded sample or undisturbed soil sample are placed the triaxial cell, in the pressure chamber, apply suction, make it get into the unsaturation stage; Apply confined pressure then unsaturated soil is carried out shear test, obtain deformation curve and intensive parameter thereof under different suction and the different confined pressures.Suction can circulation change, thereby can obtain the strength characteristic of different water power path; Can obtain the mechanical property and the hydraulics character of unsaturated soil under the different temperatures simultaneously through temperature control unit; And wherein the negative hole pressure condition of unsaturated soil near on-the-spot former bit pattern.

One, multi-functional circulation applies the unsaturated soil triaxial test device (abbreviation test unit) of suction

This test unit comprises confined pressure unit, axle power applying unit and axial displacement measuring unit, is provided with suction applying unit, temperature control unit, two pressure chamber, differential pressure pick-up, reference pipe and data acquisition unit.

Its annexation is:

Suction applying unit, confined pressure unit, axle power applying unit are connected with two pressure chambers respectively with temperature control unit, soil sample are applied suction, confined pressure, axle power and the temperature of setting;

Differential pressure pick-up is connected with two pressure chambers respectively with the axial displacement measuring unit, and differential pressure pick-up is connected with the reference pipe, and volume change in the soil sample test process and axial displacement are measured in real time;

Data acquisition unit is connected with temperature control unit with confined pressure unit, axle power applying unit respectively, the confined pressure that control is applied, axle power and temperature value;

The suction applying unit is connected with data acquisition unit, and the quality difference of record inflow and outflow solution comes to suck in the inverse soil sample or the quality of drainage water, judges simultaneously whether corresponding this one-level suction soil sample reaches equilibrium state;

Differential pressure pick-up is connected with data acquisition unit respectively with the axial displacement measuring unit, in process of the test, volume change and axial displacement is gathered in real time.

The principle of work of this test unit:

Adopt dialysis to apply required suction, its principle is to utilize the dialysis power of PEG solution.Because the PEG solution of variable concentrations produces the osmotic suction of different sizes to the moisture of the unsaturation soil sample of film opposite side through the separated retaining effect of semi-permeable diaphragm; And soil sample moisture is in change procedure; Only reached balance at the matric suction that moisture is had RETENTION BY SOILS and the osmotic suction of solution, soil sample moisture just can remain unchanged.Therefore adopt the PEG solution dialysis soil sample of variable concentrations also just to reach the purpose that soil sample is applied and controls suction.

Apply confined pressure, suction respectively through confined pressure unit and suction applying unit,, carry out the fuchsin(e)test of taking off under the different confined pressures of unsaturated soil through the real-time collection of data acquisition unit realization data;

Regulate temperature through temperature control unit, carry out the hydraulics test and the mechanical test of unsaturated soil under the different temperatures;

Connect two pressure chamber's inner rooms and reference pipe through differential pressure pick-up; When undrained shear; The volume change of soil sample can make the liquid level of the solution in two pressure chambers raise or reduce; Through reflecting the variation of soil sample volume with pressure reduction with reference to pipe, through with being connected to come in real time and gathering of data acquisition unit;

Link to each other with the top of two pressure chambers through shaft position sensor, gather in real time through data acquisition unit;

Whole process has realized under different temperatures, suction and the confined pressure condition the real-time monitoring to unsaturation soil sample mechanics and hydraulics behavior, and the difference of unsaturated soil intensity under the test different water mechanics path.

Two, multi-functional circulation this test method of unsaturated soil triaxial test method (abbreviation test method) of applying suction is based on the unsaturated soil triaxial test device that above-mentioned multi-functional circulation applies suction, comprises the following steps:

1. the installation of soil sample

Adopt static pressure method to process three soil sample (cylindrical soil samples by dry density of setting and water percentage soil sample; Be called for short soil sample); Soil sample is vacuumized saturated, then waterproof base plate is put on pressure chamber's base, soil sample is packed in the semi-permeable diaphragm; Compacting is to get rid of the air in the film slightly; Be installed in together on pressure chamber's base with waterproof base plate, be placed with waterproof cover plate, and then the two ends up and down of semi-permeable diaphragm (two ends up and down of soil sample are longer than at two ends about the semi-permeable diaphragm) are tightened respectively on the waterproof base plate and waterproof cover plate on pressure chamber's base with elastic string on the top of soil sample;

2. adopt dialysis to apply needed suction

Charge into certain density PEG solution to two pressure chambers inner room; The suction that each concentration is corresponding specific, the position under the top that makes solution reach inner room is leaned on a little, the certain lightweight oil of injection in the mistress then; Make lightweight oil get into inner room, reach the concordant contact of two Room liquid levels;

3. test

The native water characteristic curve of unsaturated soil under a, the test different temperatures;

The native water characteristic curve of unsaturated soil under b, the different confined pressures of test;

C, carry out the consolidation test of unsaturated soil under the different suction;

D, three drainings carrying out unsaturated soil under different suction and the different confined pressures and undrained shear test;

E, carry out the strength test of unsaturated soil under the different water power path.

The present invention has the following advantages and good effect:

1. confined pressure unit, suction applying unit and temperature control unit are controlled, can add the value of setting in advance;

2. can take off fuchsin(e)test, consolidation test, undrained shear test and draining shear test to what same soil sample was carried out unsaturated soil respectively, and be implemented in unsaturated soil mechanical property and the simultaneous determination of hydraulics character under the different temperatures;

3. can accurately measure and control volume change and axial displacement in suction, confined pressure, temperature and the process of the test of unsaturation soil sample;

4. do not adopt a translation technology, can reproduce the negative hole pressure condition of unsaturated soil under the presence states;

5. can realize that soil sample circulation takes off moisture absorption, carry out the strength test of unsaturated soil under the different water mechanics history;

6. realize the real-time monitoring of all test figures and collection automatically, do not need artificial reading on duty;

7. this device to test principle is directly perceived, simple in structure, precision is high, good stability, no heavy equipment, easy operating, convenient disassembly and cheap, and the installation testing personnel are not had very high technical requirement.

The present invention is applicable to and takes off moisture absorption, fixed, undrained shear and draining shear test under the unsaturated soil different temperatures, and can realize the strength test under the different water power path.

Description of drawings

Fig. 1 is the block diagram of this test unit;

Fig. 2 is the structural representation of this test unit;

Fig. 3 is the data acquisition unit block diagram;

Fig. 4 is the workflow diagram of computing machine.

Among the figure:

0-soil sample;

1-suction applying unit,

1.1-semi-permeable diaphragm, the PEG of 1.2-variable concentrations (polyglycol) solution,

1.3-normal flow pump;

2-confined pressure unit,

2.1-pressure controller, the 2.2-lightweight oil, the 2.3-tensimeter,

2.4-confined pressure valve;

3-axle power applying unit,

3.1-lifting table, 3.2 handwheels,

3.3-axial dynamometer, 3.4-testing machine;

The 4-temperature control unit,

4.1-resistance wire, 4.2-compressor, 4.3-temperature controller;

5-two pressure chambers,

5.1-inner room, 5.2-mistress, 5.3-confined pressure duct,

5.4-suction duct, 5.5-exhaust passage, 5.6-base,

5.7-waterproof base plate, the waterproof cover plate of 5.8-;

The 6-differential pressure pick-up;

7-is with reference to pipe;

8-axial displacement measuring unit,

8.1-the axial displacement dial gauge, 8.2 displacement surveymeters;

9-data acquisition unit,

9.1-confined pressure sensor, 9.2-flow sensor, 9.3-axial force sensor,

9.4-temperature sensor, 9.5-shaft position sensor, 9.6-data collecting instrument,

9.7-computing machine.

Embodiment

Specify below in conjunction with accompanying drawing and embodiment:

One, test unit

1, overall

Like Fig. 1, this test unit comprises confined pressure unit 2, axle power applying unit 3 and axial displacement measuring unit 8;

Be provided with suction applying unit 1, temperature control unit 4, two pressure chamber 5, differential pressure pick-up 6, reference pipe 7 and data acquisition unit 9;

Its annexation is:

Suction applying unit 1, confined pressure unit 2, axle power applying unit 3 are connected with two pressure chambers 5 respectively with temperature control unit 4, soil sample 0 are applied suction, confined pressure, axle power and the temperature of setting;

Differential pressure pick-up 6 is connected with two pressure chambers 5 respectively with axial displacement measuring unit 8, and differential pressure pick-up 6 is connected with reference pipe 7, and volume change and axial displacement in soil sample 0 process of the test are measured in real time;

Data acquisition unit 9 is connected with temperature control unit 4 with confined pressure unit 2, axle power applying unit 3 respectively, the confined pressure that control is applied, axle power and temperature value;

Suction applying unit 1 is connected with data acquisition unit 9, and the quality difference of record inflow and outflow solution comes to suck in the inverse soil sample 0 or the quality of drainage water, judges simultaneously whether corresponding this one-level suction soil sample 0 reaches equilibrium state;

Differential pressure pick-up 6 is connected with data acquisition unit 9 respectively with axial displacement measuring unit 8, in process of the test, volume change and axial displacement is gathered in real time.

2, functional block

1) the suction applying unit 1

Like Fig. 2, suction applying unit 1 comprises PEG (polyglycol) solution 1.2 and normal flow pump 1.3 of semi-permeable diaphragm 1.1, variable concentrations;

Its annexation is:

Semi-permeable diaphragm 1.1 parcel soil samples 0; Charge into certain density PEG solution 1.2 to two pressure chambers inner room 5.1; Corresponding suction is provided, and normal flow pump 1.3 links to each other with inner room 5.1 both sides, two pressure chambers, and side circulation provides the PEG solution 1.2 of constant flow rate; Opposite side flows out solution and writes down its mass change, is used for drawing the quality of soil sample 0 absorption or drainage water;

Normal flow pump 1.3 links to each other with data acquisition unit 9 through signal transmssion line.

The principle of work of suction applying unit 1 is:

Adopt dialysis to apply suction, at a certain temperature, the PEG solution 1.2 of every kind of concentration all has the suction value of a correspondence.Semi-permeable diaphragm 1.1 is a kind ofly can only see through micromolecular material, and the effect of semi-permeable diaphragm 1.1 is exactly to separate PEG solution 1.2 and test soil sample 0, and hydrone can pass through, and the PEG molecule of macromolecule can't pass through.Because the suction during original state in the soil sample 0 is different with the suction in pressure chamber's inner room 5.1, in order to reach balance, beginning dehumidification or moisture absorption in the soil sample 0 are until reaching balance.When soil sample 0 no longer during water outlet, promptly suction in the soil sample 0 and the suction in the PEG solution 1.2 reach balance, thereby have realized applying of suction.In order to guarantee the dialysis effect, the PEG solution 1.2 in pressure chamber's inner room 5.1 is through the successively supply of normal flow pump 1.3.Semi-permeable diaphragm 1.1 can adopt bag filter, if its specification is MWCO value 3500, representes that molecular weight is higher than 3500 macromolecular compound and can't passes promptly and can be held back by this kind bag filter.PEG solution 1.2 is the abbreviation of polyethylene glycol, should adopt PEG6000 solution.During different temperatures, on the rating curve of the concentration of this type PEG solution 1.2 and suction, can check in the suction value of corresponding variable concentrations.Soil sample 0 adopts peripheral draining or suction, and it is short to reach the required time of balance, has practiced thrift the time of whole test greatly.

The function of suction applying unit 1 is:

Soil sample 0 is applied the suction of setting; Can reproduce the negative hole pressure condition of unsaturated soil under the on-the-spot original position state; Carry out the triaxial test of unsaturated soil under the given suction, and measure the quality of soil sample 0 absorption or drainage water, can measure the volume change of triaxial test simultaneously through normal flow pump 1.3.

2) the confined pressure unit 2

Described confined pressure unit 2 (being a functional unit of existing " saturated soil triaxial test equipment ") comprises pressure controller 2.1, lightweight oil 2.2, tensimeter 2.3 and confined pressure valve 2.4;

Its annexation is:

In the mistress of pressure chamber 5.2, be full of lightweight oil 2.2, pressure controller 2.1, confined pressure valve 2.4 and lightweight oil 2.2 are communicated with successively, and pressure controller 2.1 is provided with tensimeter 2.3.

The principle of work of confined pressure unit 2 is:

2.1 pairs of lightweight oils 2.2 of pressure controller are exerted pressure and are produced the confined pressure of setting, and confined pressure valve 2.4 and tensimeter 2.3 are used for setting and showing the numerical value of confined pressure respectively, and tensimeter 2.3 links to each other with data acquisition unit 9 through signal transmssion line, controls and monitors.

The function of confined pressure unit 2 is:

Soil sample 0 is applied required confined pressure, and that carries out unsaturated soil under the different confined pressures takes off moisture absorption, fixed and shear test.

3) axle power applying unit 3

Axle power applying unit 3 (being functional units of existing " saturated soil triaxial test equipment ") comprise lifting table 3.1, handwheel 3.2, axial dynamometer 3.3 and testing machine 3.4;

Its annexation is:

From top to bottom, testing machine 3.4, lifting table 3.1, two pressure chamber 5 and axial dynamometer 3.3 are connected successively, apply a power for soil sample 0;

Testing machine 3.4 is provided with handwheel 3.2, plays the unloading effect.

The principle of work of axle power applying unit 3 is:

It is the strain control type that axle power applies, and drives lifting table 3.1 through testing machine 3.4 with certain speed and rises, and the axial strain of soil sample 0 is increasing always, and realization applies soil sample 0 axial force, destroys until soil sample 0.The axle power value that obtains applying through axial dynamometer 3.3, and gather through being connected in real time with data acquisition unit 9.

The function of axle power applying unit 3 is:

Soil sample 0 is applied a power, carry out three draining shearings and undrained shear test under different confined pressures, temperature and the suction condition.

Lifting table 3.1, handwheel 3.2, axial dynamometer 3.3 and testing machine 3.4 are general part.

4) temperature control unit 4

Temperature control unit 4 is a kind of general air conditioner structures, comprises resistance wire 4.1, compressor 4.2 and temperature controller 4.3;

Its annexation is:

Resistance wire 4.1 is built in the two mistress of pressure chamber 5.2 inwalls, and compressor 4.2 is communicated with two mistress of pressure chamber 5.2 through flexible pipe, and temperature controller 4.3 is connected with compressor 4.2 with resistance wire 4.1 respectively, the control temperature.

The principle of work of temperature control unit 4 is:

Through temperature controller 4.3 set the temperature that will reach; If the temperature in the solution heats than the low 4.1 pairs of liquid of built-in resistance wire that then feed back to of setting value; Lower the temperature if the temperature in the solution then feeds back to compressor 4.2 than setting value height, and keep temperature constant.

The function of temperature control unit 4 is:

Can set needed temperature, and keep constant temperature.

5) two pressure chambers 5

Two pressure chambers 5 comprise inner room 5.1, mistress 5.2, confined pressure duct 5.3, two suction ducts 5.4, exhaust passage 5.5, base 5.6, waterproof base plate 5.7 and waterproof cover plates 5.8;

Its annexation is:

Inner room 5.1 is installed in respectively on the base 5.6 with mistress 5.2, and the open upper end of inner room 5.1 is communicated with mistress 5.2;

Confined pressure duct 5.3 is arranged on the base 5.6 that is communicated with mistress 5.2, is used for applying confined pressure;

One termination in two suction ducts 5.4 is arranged on the base 5.6 that is communicated with inner room 5.1; Another termination in two suction ducts 5.4 is communicated with normal flow pump 1.3, is used for the variation of moisture and the volume change in the triaxial test process in circulation-supplied PEG solution 1.2 and the measurement soil sample 0;

Exhaust passage 5.5 is arranged on the top of two pressure chambers 5, is used for getting rid of indoor air.

The principle of work of two pressure chambers 5 is:

In inner room 5.1, inject PEG solution 1.2, be used to apply the suction of soil sample 0; In mistress 5.2, inject the confined pressure that lightweight oil 2.2 is used to apply soil sample 0, soil sample 0 is placed on the inner room base 5.6; In two pressure chambers 5, inner room 5.1 and mistress's 5.2 pressure equates, has offset the distortion of inner room 5.1, thereby more can accurately measure the volume change of soil sample 0 (unsaturated soil); Top at inner room 5.1 is provided with scale mark, is used to control the maximum height of injecting solution.

The function of two pressure chambers 5 is:

Place soil sample 0, realize that soil sample 0 takes off moisture absorption, fixed and shear test under different temperatures and different confined pressures.

6) differential pressure pick-up 6

Differential pressure pick-up 6 is a kind of general parts.

One end links to each other with inner room 5.1, and the other end links to each other with reference pipe 7.When the undrained shear of soil sample 0 (unsaturated soil); Because soil sample 0 volume change can make the liquid level of the PEG solution 1.2 in the inner room 5.1 change; With can produce corresponding variation with reference to the pressure differential of pipe in 7, through can the convert volume change of soil sample 0 (unsaturated soil) in the test of this pressure differential.Through linking to each other, can monitor body in real time and become simultaneously with data acquisition unit 9.

7) with reference to pipe 7

With reference to pipe 7 are glass tubes that are full of PEG solution 1.2, and the liquid level of PEG solution 1.2 is constant, so pressure is also constant, has played the effect of a reference.The very thin lightweight oil of one deck is arranged on the liquid level, avoid evaporating.Inner room 5.1 can obtain the pressure differential of inner room 5.1 and reference pipe 7 through linking to each other with differential pressure pick-up 6.

8) the axial displacement measuring unit 8

Axial displacement measuring unit 8 (being a functional unit of existing " saturated soil triaxial test equipment ") comprises axial displacement dial gauge 8.1 and displacement surveymeter 8.2;

Its annexation is:

Offset table 8.1 links to each other with data acquisition unit 9 through signal transmssion line, and displacement surveymeter 8.2 contacts with 5 tops, two pressure chamber.

The function of axial displacement measuring unit 8 is:

Can monitor unsaturated soil in real time and take off the axial displacement that takes place in moisture absorption, the fixed and shear test process.

9) data acquisition unit 9

As shown in Figure 3, data acquisition unit 9 comprises confined pressure sensor 9.1, flow sensor 9.2, axial force sensor 9.3, temperature sensor 9.4, shaft position sensor 9.5, data collecting instrument 9.6 and computing machine 9.7;

Its annexation is:

Have six passages to be connected with confined pressure sensor 9.1, flow sensor 9.2, axial force sensor 9.3, temperature sensor 9.4, shaft position sensor 9.5 and differential pressure pick-up 6 respectively on the data collecting instrument 9.6, data collecting instrument 9.6 is connected with computing machine 9.7;

Confined pressure sensor 9.1 is arranged on the tensimeter 2.3;

Flow sensor 9.2 is arranged on the normal flow pump 1.3;

Axial force sensor 9.3 is arranged on the axial dynamometer 3.3;

Temperature sensor 9.4 is arranged on the temperature controller 4.3;

Shaft position sensor 9.5 is arranged on the dial gauge 8.1;

Be connected with data collecting instrument 9.6 through signal transmssion line respectively.

The function of data acquisition unit 9 is:

Through confined pressure, the temperature in confined pressure sensor 9.1, temperature sensor 9.4 controls and the two pressure chambers 5 of measurement; Can draw soil sample 0 real-time axial force and axial displacement respectively through axial force sensor 9.3, shaft position sensor 9.5; Can obtain in the soil sample 0 absorbing or the quality of drainage water through flow sensor 9.2, and can obtain the volume change of triaxial test simultaneously; Can obtain the volume change of unsaturated soil in the undrained shear process through differential pressure pick-up 6.

(1) the confined pressure sensor 9.1

Confined pressure sensor 9.1 is a kind of general parts, selects Senex production for use, pressure limit: 0～1Mpa, precision: 0.1%FS.Its function is: the confined pressure of appearance 0 in the measurement.

(2) flow sensor 9.2

Flow sensor 9.2 is a kind of general parts, selects Ponolflow-VA for use, measurement range :-5m/s～6.5m/s, resolution: lmm/s, precision: 0.5%.Its function is: flow velocity, instantaneous delivery and the integrated flux of measuring solution.

(3) axial force sensor 9.3

Axial force sensor 9.3 is a kind of general parts, selects KAP-S type pull pressure sensor for use, and specification is: 5N～50kN.Its function is: the axle power of measuring soil sample 0.

(4) temperature sensor 9.4

Temperature sensor 9.4 is a kind of general parts; Select Pt100 type platinum resistance (Beijing, ) for use.Its function is: measure soil sample 0 temperature of solution on every side.

(5) differential pressure pick-up 6

Differential pressure pick-up 6 is a kind of general parts, selects Senex production for use, pressure limit: 0～1Mpa, precision: 0.1%FS.Its function is: measure the pressure reduction of two pressure chamber's inner rooms and reference pipe, thereby can obtain the volume change value in soil sample 0 process of the test.

(6) shaft position sensor 9.5

Shaft position sensor 9.5 is a kind of general parts; Select ZKL-W type displacement transducer (LVDT) for use; Range 0～800mm, diameter for its function is: the axial deformation of soil sample 0 in the experiment with measuring process.

(7) data collecting instrument 9.6

Data collecting instrument 9.6 is a kind of general parts, the TSW-3 that selects for use Nanjing to produce.

(8) computing machine 9.7

The Hardware configuration of computing machine 9.7 is: Intel (R) Celeron (R) CPU 4201.6GHZ; The 512MB internal memory.

Its acquisition software adopts the Si Mingte data acquisition software SUPY1.0 of Si Mingte company exploitation.Data can be set, and are accurate to 0.1, can show curve data in real time.

Like Fig. 4, its workflow is:

1. start acquisition software A;

2. setting data storing path B;

3. set acquisition interval time C;

4. turn-on data acquisition channel D;

5. import soil sample physical parameter E;

6. data zero clearing F;

7. begin to test G.

Two, test method

Present embodiment is example with the silt, and the process of the unsaturated soil triaxial test of using the present invention to circulate to apply suction is:

1. the installation of soil sample

Adopt static pressure method to process three soil samples 0 (cylindrical soil sample is called for short soil sample) by dry density of setting and water percentage soil sample 0, soil sample 0 is vacuumized saturated, the saturated quality afterwards of weighing draws saturation moisture content and porosity.Then waterproof base plate 5.7 is put on pressure chamber's base 5.6; Soil sample 0 is packed in the semi-permeable diaphragm 1.1; Compacting is to get rid of the air in the film slightly; Be installed in together on pressure chamber's base 5.6 with waterproof base plate 5.7, be placed with waterproof cover plate 5.8 on the top of soil sample 0, and then the two ends up and down of semi-permeable diaphragm 5.1 (two ends up and down of soil sample are longer than at two ends about the semi-permeable diaphragm) are tightened respectively on waterproof base plate on pressure chamber's base 5.6 5.7 and waterproof cover plate 5.8 with elastic string;

2. adopt dialysis to apply needed suction

Inner room 5.1 charges into certain density PEG solution 1.2 toward two pressure chambers; The suction that each concentration is corresponding specific; Make top that solution 1.2 reaches inner room 5.1 a little by under the position; In mistress 5.2, inject certain lightweight oil 2.2 then, make lightweight oil 2.2 get into inner room, two Room liquid levels are combined;

3. test:

The native water characteristic curve of unsaturated soil under a, the test different temperatures

Set needed temperature through temperature control unit 4.Under different temperature, carry out the fuchsin(e)test of taking off of soil sample 0.Every kind of temperature is all to the concentration that PEG solution should be arranged and the calibration curve of suction.Corresponding to each grade suction value that sets, prepare the solution 1.2 of respective concentration.A suction duct 5.4 of 5 bottoms, two pressure chamber is opened, adopt normal flow pump 1.3 that solution 1.2 is full of two pressure chambers 5.After solution 1.2 is full of, open two suction ducts 5.4, the end that normal flow pump 1.3 is connected with inner room 5.1 is constantly supplied solution, and the other end constantly flows out.And discharge can be monitored in real time, so just can obtain the quality of drainage water in the soil sample 0.When discharge was constant, then this grade suction reached balance, can obtain the water cut or the saturation degree of corresponding this one-level suction through saturated water cut.Then the solution in two pressure chambers 5 is discharged, adopt above-mentioned same method to inject the solution 1.2 of next stage suction institute corresponding concentration.So repeatedly, test can not only obtain main dehumidification curve and main sucting wet curve, can also obtain the sweep trace of the inside simultaneously.Because soil sample 0 peripheral draining or suction, required equilibration time is short, can save the time of whole test like this.

Through temperature control unit 4, set the next stage temperature, repeat above-mentioned process of the test, can obtain native water characteristic relation complete under the different temperatures.

The native water characteristic curve of unsaturated soil under b, the different confined pressures of test

Corresponding to each grade suction value that sets, the solution 1.2 of preparation respective concentration.A suction duct 5.4 of 5 bottoms, two pressure chamber is opened, adopt normal flow pump 1.3 that solution is injected two pressure chambers inner room 5.1.When reaching the maximum scale line of inner room 5.1, stop to inject.Then the exhaust passage at 5 tops, two pressure chamber is opened, in pressure chamber 5, fill lightweight oil 2.2.Lightweight oil 2.2 has individual surface of contact with solution 1.2 at maximum scale line place.2 pairs of pressure chambers 5 apply the confined pressure that sets through the confined pressure unit.Open two suction ducts 5.4 in the inner room 5.1, the end that normal flow pump 1.3 is connected with inner room 5.1 is constantly supplied solution, and the other end constantly flows out.And discharge can be monitored in real time, so just can obtain discharging or absorbing in the soil sample 0 quality of water.When discharge was constant, then this grade suction reached balance, can obtain the water cut or the saturation degree of corresponding this one-level suction through saturated water cut.Then solution in two pressure chambers 5 1.2 and lightweight oil 2.2 are discharged, adopt above-mentioned same method to carry out the test of next stage suction.So repeatedly, test can not only obtain main dehumidification curve and main sucting wet curve, can also obtain the sweep trace of the inside simultaneously.Because soil sample 0 peripheral draining or suction, required equilibration time is short, can save the time of whole test like this.

Through confined pressure unit 2, set the next stage confined pressure, repeat above-mentioned process of the test, can obtain native water characteristic relation complete under the different confined pressures.

In conjunction with above under the different temperatures unsaturated soil take off fuchsin(e)test, can control confined pressure and temperature simultaneously, obtain the complete native water characteristic curve of unsaturated soil under different temperatures and the different confined pressures.

C, carry out the consolidation test of unsaturated soil under the different suction

With the similar suction that sets that applies of b test, begin to apply confined pressure after the isoequilibrium.Normal flow pump 1.3 is supplied the solution 1.2 of respective concentration always, keeps solution 1.2 on the maximum scale line, to contact with lightweight oil 2.2 always.Can obtain the variation of soil sample 0 volume through the fluctuations in discharge of normal flow pump 1.3 opposite sides of real-time monitoring.

Apply the next stage confined pressure then, the process above repeating also can be done the test of unloading resilience simultaneously.The isotropy compression test of unsaturated soil under like this can controlled different suction.

Can also change temperature through temperature control unit 4 simultaneously, obtain the compression test under the different temperatures.

D, three drainings carrying out unsaturated soil under different suction and the different confined pressures and undrained shear test

The method that adopts the front to describe applies needed confined pressure and suction, carries out three drainings and the disdrainage test of unsaturated soil.

Three not drainings of unsaturated soil are cut soon: when soil sample 0 when confined pressure and suction reach balance, axial displacement surveymeter 8.2 contacts 8.1 zero clearings of displacement dial gauge with two pressure chambers 5.Starting characteristics test machine 3.4, lifting table 3.1 rises, and under different confined pressures, soil sample 0 is carried out undrained quick shear test.Shear strain rate is selected according to different soil properties, can be with reference to normal triaxial.Measure inner room 5.1 and, can obtain the body change of soil sample 0 through differential pressure pick-up 6 with reference to the pressure differential of managing 7.Can gather a power, axial displacement and body in real time through data acquisition unit 9 becomes.

Three draining shear tests of unsaturated soil: when soil sample 0 when confined pressure and suction reach balance, axial displacement surveymeter 8.2 contacts 8.1 zero clearings of displacement dial gauge with two pressure chambers 5.Starting characteristics test machine 3.4, lifting table 3.1 rises, and under different confined pressures, soil sample 0 is carried out the draining shear test.Shear strain rate is selected according to different soil properties, can be with reference to normal triaxial.Measure inner room 5.1 and, can obtain the body change of soil sample 0 through differential pressure pick-up 6 with reference to the pressure differential of managing 7.Can gather a power, axial displacement and body in real time through data acquisition unit 9 becomes.

As described above, can carry out the test under the different temperatures.

E, carry out the strength test of unsaturated soil under the different water power path

Different with saturated soil, the character of unsaturated soil is not only relevant with stress history, but also relevant with hydraulics history.For same suction, the hydraulics path that reaches this suction is different, also can cause different mechanical character.Such as, reaching the suction value of setting respectively through dehumidification and moisture absorption path, the intensity of unsaturated soil is different with deformation characteristic under two kinds of paths.Therefore this device can repeatedly take off the moisture absorption cyclic test, obtains the intensive parameter under the different water power path, for later unsaturated soil subject development provides some experimental basis.

Claims (7)

1. a multi-functional unsaturated soil triaxial test device that applies suction comprises confined pressure unit (2), axle power applying unit (3) and axial displacement measuring unit (8);

It is characterized in that:

Be provided with suction applying unit (1), temperature control unit (4), two pressure chamber (5), differential pressure pick-up (6), reference pipe (7) and data acquisition unit (9);

Its annexation is:

Suction applying unit (1), confined pressure unit (2), axle power applying unit (3) are connected with two pressure chambers (5) respectively with temperature control unit (4), soil sample (0) are applied suction, confined pressure, axle power and the temperature of setting;

Differential pressure pick-up (6) is connected with two pressure chambers (5) respectively with axial displacement measuring unit (8), and differential pressure pick-up (6) is connected with reference pipe (7), and volume change and axial displacement in soil sample (0) process of the test are measured in real time;

Data acquisition unit (9) is connected with temperature control unit (4) with confined pressure unit (2), axle power applying unit (3) respectively, the confined pressure that control is applied, axle power and temperature value;

Suction applying unit (1) is connected with data acquisition unit (9), and the quality difference of record inflow and outflow solution is come the quality of middle suction of inverse soil sample (0) or drainage water, judges simultaneously whether corresponding this one-level suction soil sample (0) reaches equilibrium state;

Differential pressure pick-up (6) is connected with data acquisition unit (9) respectively with axial displacement measuring unit (8), in process of the test, volume change and axial displacement is gathered in real time.

2. by the described a kind of multi-functional unsaturated soil triaxial test device that applies suction of claim 1, it is characterized in that:

Described suction applying unit (1) comprises the PEG solution (1.2) and the normal flow pump (1.3) of semi-permeable diaphragm (1.1), variable concentrations;

Semi-permeable diaphragm (1.1) parcel soil sample (0); Charge into certain density PEG solution (1.2) to two pressure chambers inner rooms (5.1); Corresponding suction is provided, and normal flow pump (1.3) links to each other with two pressure chamber's inner room (5.1) both sides, and side circulation provides the PEG solution (1.2) of constant flow rate; Opposite side flows out solution and writes down its mass change, is used for drawing the quality of soil sample (0) absorption or drainage water;

Normal flow pump 1.3 links to each other with data acquisition unit (9) through signal transmssion line.

3. by the described a kind of multi-functional unsaturated soil triaxial test device that applies suction of claim 1, it is characterized in that:

Described temperature control unit (4) is a kind of general air conditioner structure, comprises resistance wire (4.1), compressor (4.2) and temperature controller (4.3);

Resistance wire (4.1) is built in the two mistress of pressure chamber (5.2) inwalls, and compressor (4.2) is communicated with two mistress of pressure chamber (5.2) through flexible pipe, and temperature controller (4.3) is connected with compressor (4.2) with resistance wire (4.1) respectively, the control temperature.

4. by the described a kind of multi-functional unsaturated soil triaxial test device that applies suction of claim 1, it is characterized in that:

Described pair of pressure chamber (5) comprises inner room (5.1), mistress (5.2), confined pressure duct (5.3), two suction ducts (5.4), exhaust passage (5.5), base (5.6), waterproof base plate (5.7) and waterproof cover plate (5.8);

Inner room (5.1) and mistress (5.2) are installed in respectively on the base (5.6), and the open upper end of inner room (5.1) is communicated with mistress (5.2);

Confined pressure duct (5.3) is arranged on the base (5.6) that is communicated with mistress (5.2), is used for applying confined pressure;

One termination in two suction ducts (5.4) is arranged on the base (on 5.6) that is communicated with inner room (5.1); Another termination in two suction ducts (5.4) is communicated with normal flow pump (1.3), is used for circulation-supplied PEG solution (1.2) and the variation of the middle moisture of measurement soil sample (0) and the volume change in the triaxial test process;

Exhaust passage (5.5) is arranged on the top of two pressure chambers (5), is used for getting rid of indoor air.

5. by the described a kind of multi-functional unsaturated soil triaxial test device that applies suction of claim 1, it is characterized in that:

Described data acquisition unit (9) comprises confined pressure sensor (9.1), flow sensor (9.2), axial force sensor (9.3), temperature sensor (9.4), shaft position sensor (9.5), data collecting instrument (9.6) and computing machine (9.7);

Have six input channels to be connected with confined pressure sensor (9.1), flow sensor (9.2), axial force sensor (9.3), temperature sensor (9.4), shaft position sensor (9.5) and differential pressure pick-up (6) respectively on the data collecting instrument (9.6), the output terminal of data collecting instrument (9.6) is connected with computing machine 9.7;

Confined pressure sensor (9.1) is arranged on the tensimeter (2.3);

Flow sensor (9.2) is arranged on the normal flow pump (1.3);

Axial force sensor (9.3) is arranged on the axial dynamometer (3.3);

Temperature sensor (9.4) is arranged on the temperature controller (4.3);

Shaft position sensor (9.5) is arranged on the dial gauge (8.1).

6. by the described a kind of multi-functional unsaturated soil triaxial test device that applies suction of claim 1, it is characterized in that:

Described computing machine 9.7 its acquisition softwares adopt the Si Mingte data acquisition software SUPY1.0 of Si Mingte company exploitation, and its workflow is:

1. start acquisition software (A);

2. setting data storing path (B);

3. set the acquisition interval time (C);

4. turn-on data acquisition channel (D);

5. import soil sample physical parameter (E);

6. data zero clearing (F);

7. begin test (G).

7. based on by the described a kind of multi-functional unsaturated soil triaxial test device that applies suction of claim 1

Test method, it is characterized in that this test method comprises the following steps:

1. the installation of soil sample

Adopt static pressure method to process three soil samples by dry density of setting and water percentage soil sample; Soil sample is vacuumized saturated, then waterproof base plate is put on pressure chamber's base, soil sample is packed in the semi-permeable diaphragm; Compacting is to get rid of the air in the film slightly; Be installed in together on pressure chamber's base with waterproof base plate, be placed with waterproof cover plate, and then the two ends up and down of semi-permeable diaphragm are tightened respectively on the waterproof base plate and waterproof cover plate on pressure chamber's base with elastic string on the top of soil sample;

2. adopt dialysis to apply needed suction

Charge into certain density PEG solution to two pressure chambers inner room; The suction that each concentration is corresponding specific, the position under the top that makes solution reach inner room is leaned on a little, the certain lightweight oil of injection in the mistress then; Make lightweight oil get into inner room, reach the concordant contact of two Room liquid levels;

3. test

The native water characteristic curve of unsaturated soil under a, the test different temperatures;

The native water characteristic curve of unsaturated soil under b, the different confined pressures of test;

C, carry out the consolidation test of unsaturated soil under the different suction;

D, three drainings carrying out unsaturated soil under different suction and the different confined pressures and undrained shear test;

E, carry out the strength test of unsaturated soil under the different water power path.