CN103604696A - Local triaxial test method for bituminous mixture and radial displacement test device for bituminous mixture - Google Patents

Abstract

The invention discloses a radial displacement test device which comprises a ring-shaped chain connection pipe, pulleys, a spring, an adjustment bolt, an adjustment bolt fixing device, a fixing screw I, a fixing screw II, a linear displacement sensor fixing device and linear displacement sensors. The invention also discloses a local triaxial test method for a bituminous mixture. Two linear variable differential transformers (LVDT) are mounted and are used for measuring axial strain; one LVDT for measuring radial strain can be used for measuring radial and axial deformations of the bituminous mixture, namely measuring radial expansion deformation and axial contraction deformation of a bituminous mixture test piece. The local triaxial test method and the radial displacement test device provided by the invention can be used for testing the shear performance of a bituminous pavement and simulating an actual pavement which is horizontally changed along with the type, the temperature and the stress of the mixture; furthermore, a corresponding test method, a principle, operating steps and the like are provided; the test method and the device have extremely high generalization performance.

Description

Asphalt partial triaxial test and radial displacement proving installation thereof

Technical field

The present invention relates to a kind of test method and device of road engineering material, be specifically related to a kind of asphalt partial triaxial test and radial displacement proving installation thereof, the cylindrical bitumen mixture specimen designing for the actual confined pressure that can provide of bituminous pavement, is radially expanded distortion and radial shrinkage is out of shape with the actual road surface of analog computation load-bearing situation by measuring it.

Background technology

The development of the development of bituminous pavement and experimental test technology is closely related.Triaxial apparatus is one of most important test apparatus, the development of road subject has been played to very important effect, yet there is many defects and deficiency in the existing deformation measurement method of triaxial test, transformation triaxial test and deformation measuring device, can overcome these defects and deficiency, for asphalt triaxial test provides a kind of new, more reasonable effectively deformation measurement means.The improvement of three axle test specimen radial deformation measuring methods can be divided into two classes substantially: a class be take electrical measurement or electromagnetic measurement as main, another kind ofly take flash ranging as main.First kind electrical measurement or electromagnetic measurement be take strain gage testing as representative, and it is out of shape the distortion of determining test specimen with the Copper Foil that is arranged on test specimen outer wall, and its shortcoming is can not be applicable to large deformation and use operating difficulties.

Conventional radial deformation measuring method is indirectly to convert and obtain according to actual measurement axial deformation and volume change, and its measuring principle is the product that the volume of cylindrical sample equals cylinder area and cylinder height.Therefore, the problem that the method exists is that what to obtain is average radial distortion, can not reflect radial deformation virtual condition.Some improved measuring methods had been there are afterwards: local displacement sensor LDT and radial strain instrument, resistance strain gage is a kind of sensitive element of resistance-type, generally substrate, sensitive grid, overlayer and lead-in wire four parts, consists of.Being distributed in the substrate that an organic material makes of a resistance wire machinery, become a slice foil gauge.Its test philosophy is: under external force, when measurand surface produces milli machine distortion, foil gauge sensitive grid is also in company with distortion, its resistance value generation respective change.The problem existing mainly contains: the method is contact type measurement, easily produces disturbance; Be difficult to adapt to large deformation; Operating difficulties while measuring in water.The displacement transducer that David M.Cole proposes, its principle is the eddy current principle that adopts Kaman Multi-Vriei, the method deficiency is that measuring accuracy is not high and static drift is serious.Optical measuring instrument is also a kind of improvement displacement measuring instrument wherein, and its principle is outline line by determining vertical markings on pressure chamber's outer cover and the specimen finish reading variation conversion specimen finish on nonadjustable signal, and weak point is that measuring accuracy is not high.In addition, it is a kind of improvement displacement measurement method wherein that microscope is surveyed the method for reading, its principle is that banded aluminium case is around also pasted on rubbery membrana dermalis with thin layer silicone grease around sample, change amount by the distance between micro-aobvious mirror survey read flag with mensuration sample girth, the shortcoming of the method is operating difficulties, and survey is read workload greatly and is contact type measurement.

In order to evaluate the shear behavior of asphalt, lot of domestic and international scholar has carried out triaxial shear test.Conventional triaxial compression test is a kind of fairly perfect method of measuring soil or other bulk solid sample shearing strength, can obtain some important engineering mechanics property of sample, as shearing strength, cohesion and angle of internal friction etc.And for the shear behavior evaluation of asphalt, institute carries out triaxial test method and Practical Project situation also exists larger gap, and triaxial test process is more complicated, and cost is relatively costly.The features such as that the local triaxial test that therefore, this patent proposes has is simple to operate, data are reliable, with low cost.

The device of at present cylindrical rock sample radial deformation being measured mainly contains loop chain type, distortion chip etc.These devices can be divided into two classes: 1. measurement mechanism is fixed on bitumen mixture specimen surface and is measured: this class device can Measurement accuracy test specimen same point is radially expanded distortion, but cannot measure rock sample radial shrinkage distortion (when the rock sample that is increasing substantially confined pressure or some rock (as rock salt) because of conditions such as solution osmosis dissolvings under, rock sample will produce radial shrinkage and be out of shape); 2. measurement mechanism is fixed on some motionless parts (as pressure head) of testing machine and measures: this class device can be measured the radial shrinkage distortion of rock sample, but measure contact point, with rock sample, change, can not accurately reflect the radial variations rule of rock sample same point.

Summary of the invention

The object of the invention is in order more to approach the actual load-bearing situation of bituminous pavement, evaluate the shear behavior of asphalt, advantage in conjunction with uniaxial penetration test and triaxial test, a kind of asphalt partial triaxial test and radial displacement proving installation thereof are provided, this device can utilize test specimen that the confined pressure becoming with test condition (as temperature, loading condition etc.) is provided, simulate truly actual bituminous pavement load-bearing situation, measure the radial and axial deformation measurement of asphalt, measure being radially expanded with axial shrinkage of bitumen mixture specimen and be out of shape.

The technical solution used in the present invention is: a kind of radial displacement proving installation, comprises closed chain adapter, pulley, spring, adjusting bolt, adjusting bolt stationary installation, fixed screw one, fixed screw two, Linear displacement transducer stationary installation and Linear displacement transducer;

Described closed chain is taken over and is connected with pulley by steel bar, form the chain clamp of an opening, in this fixture, be provided with cylindrical bitumen mixture specimen, the two ends of described fixture are separately installed with adjusting bolt stationary installation and Linear displacement transducer stationary installation, adjusting bolt stationary installation with in Linear displacement transducer stationary installation, be respectively equipped with the relative hole in position, described adjusting bolt and Linear displacement transducer are positioned over respectively in above-mentioned two holes, adjusting bolt smooth end is smooth, and contact with Linear displacement transducer top is smooth, adjusting bolt is provided with fixed screw one, Linear displacement transducer is provided with fixed screw two, the opening two ends of described fixture are connected with spring, described pulley comprises interior ring and outer shroud, between interior ring and interior ring, is provided with ball.

As preferably, described closed chain is taken over and is provided with the circular hole that facilitates steel bar to pass.

As preferably, described Linear displacement transducer adopts the high-accuracy linear displacement sensor of UTM configuration.

The pulling force of radial displacement proving installation fixture of the present invention by spring is strapped in right cylinder test specimen surface, by the rolling of bearing and the stretching of spring, keeps harmonious with test piece deformation.There are respectively two holes at the two ends of fixture, and a hole is used for placing displacement transducer, and another hole is screwed into bolt, and bolt smooth end is smooth to be contacted with the smooth of displacement transducer top with assurance.Two Kong Jun have screw, are respectively used to fixed displacement sensor and bolt.Bolt, for regulating the distance with displacement transducer, in the deformation process of test specimen, records the variation of test specimen girth, and then can change the radial strain that draws test specimen by LVDT.

An asphalt partial triaxial test that adopts above-mentioned radial displacement proving installation, comprises the following steps:

1) test specimen is placed in to environmental chamber insulation at least 4 hours, makes it be stabilized to the test temperature of regulation;

2), after temperature stabilization, test specimen is installed; Adopt two equal pressure heads of size respectively local restriction to be carried out in test specimen two ends, make the compound regional stress between push-down head relatively even, and the pressure head on test specimen top is carried out to local loading, the compound of pressure head periphery can provide the confined pressure of variation; Test specimen is placed on bearing, and load applies by being less than the pressure head of test specimen diameter, and two LVDT are arranged on the pressure head of test specimen top end face, to measure axial strain; Radial displacement proving installation is installed at test specimen middle part, and installation steps are as follows: (1) measures test specimen, and on the middle section of test specimen, setting-out is marked; (2) will be radially test fixture be arranged on test specimen, installation site should be the middle section of test specimen, to avoid the impact of end restraint, and adjusts the center line of fixture and the mark line of test specimen overlaps, to guarantee that fixture is in the surface level perpendicular to test specimen central shaft; (3) test specimen is put under the loading pressure head of UTM, and be adjusted to center; (4) radial displacement transducer LVDT is put in hoop test fixture, adjust its initial value to correct position, tighten the screws fixation of sensor; (5) prepare test, to measure radial strain, measurement range: 0～50mm;

3) whether normal tune-up data test and acquisition system, detect LVDT reaction, and adjust LVDT to the beginning of line style scope, so that gamut is all effective to accumulation of distortion;

4) close environmental chamber time enough, make the temperature of test specimen and environmental chamber reach stable;

5) be incubated to test temperature, test specimen is applied to pre-constant load;

6) test result analysis.

As preferably, above-mentioned steps 2) in for prevent base and pressure head to the restrictions of the frictional force of test specimen the distortion of test specimen, between test specimen and pressure head, base, place double-deck latex film, between latex film, be coated with railway grease, ensure test specimen end face

Free Transform.

As preferably, above-mentioned steps 4) in, closing environmental chamber time enough is 10 to 15 minutes.

As preferably, above-mentioned steps 5) loading speed that in, test specimen is applied to pre-constant load is got 1mm/min.

The radial strain of test asphalt is difficult, also there is no ripe method of testing at present.And the present invention adopts fine this problem that solved of this hoop strain proving installation.This device is comprised of displacement transducer and chain clamp, wherein there are respectively two holes at the two ends of fixture, be respectively used to place displacement transducer and be screwed into bolt, this fixture is strapped in right cylinder test specimen surface by the pulling force of spring, by the rolling of bearing and the stretching of spring and test piece deformation, be consistent, adopt the high-accuracy linear displacement transducer LVDT test displacement of UTM configuration.Two displacement transducer LVDT test axial strains for process of the test, a displacement transducer LVDT records the variation of test specimen girth, and then changes the radial strain that draws test specimen, and conversion formula is suc as formula 1.

${\mathrm{\&epsiv;}}_c=\frac{\mathrm{\&Delta;}{L}_c}{L_c}=\frac{2\mathrm{\&pi;\&Delta;}({\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="DEST\_PATH\_HDA0000440410130000012.png,DEST\_PATH\_HDA0000440410130000041.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+r_2)}{2\mathrm{\&pi;}({\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="DEST\_PATH\_HDA0000440410130000012.png,DEST\_PATH\_HDA0000440410130000041.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+r_2)}=\frac{\mathrm{\&Delta;}{r}_1}{{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="DEST\_PATH\_HDA0000440410130000012.png,DEST\_PATH\_HDA0000440410130000041.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="DEST\_PATH\_HDA0000440410130000041.png,DEST\_PATH\_HDA0000440410130000062.png"\; state="\{\{state\}\}">r</figure-callout>}}_2}=\frac{r_1}{{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="DEST\_PATH\_HDA0000440410130000012.png,DEST\_PATH\_HDA0000440410130000041.png"\; state="\{\{state\}\}">r</figure-callout>}}_1+{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="DEST\_PATH\_HDA0000440410130000041.png,DEST\_PATH\_HDA0000440410130000062.png"\; state="\{\{state\}\}">r</figure-callout>}}_2}{\mathrm{\&epsiv;}}_r---\left(1\right)$

In formula, ε _cfor girth strain; L _cfor test specimen girth; r ₁and r ₂respectively test specimen radius and bearing radius; ε _rfor radial strain.

Adopt following steps to carry out the installation of radial strain proving installation: 1. to measure test specimen, mark test specimen middle section; 2. radial strain test clip is installed in test specimen middle section, and is adjusted the center line of fixture and the mark line of test specimen overlaps, to guarantee that fixture is in the surface level perpendicular to test specimen central shaft; 3. test specimen is put under the loading pressure head of UTM, and be adjusted to center; 4. radial strain displacement transducer LVDT is put in hoop test fixture, adjusted its initial value to correct position, tighten the screws fixation of sensor.

The test principle of this device: local triaxial test improves on traditional triaxial test and uniaxial penetration test basis.Any stress state of bituminous pavement, can represent by uniaxial compression test at first, and in this and actual road surface, any point stressing conditions also has bigger difference, and any point all has confined pressure restriction.Therefore, by triaxial compression test, represent, this can people for applying confined pressure, to simulate bituminous pavement situation.The suffered confined pressure of the confined pressure that triaxial compression test applies and bituminous pavement any point is still had any different, if the confined pressure in test is directly provided by test specimen, truth that can actual reflection road surface, can adopt partial triaxial test.Local triaxial test has advantages of triaxial compression test and uniaxial penetration test, can simulate actual road surface side to constraint condition, has clear and definite stress-strain state.Local triaxial test principle is exactly the constraint that two ends apply homalographic on test specimen, and in the pressurization of test specimen upper end steel pressure head, with the actual forced status in simulated roadway, then by the derivation of mechanics formula, obtains the shear behavior of asphalt.The diameter of pressure head (d) is less than the diameter (D) of test specimen, and the ratio of both diameters is d/D, and this ratio is less, more can act on the actual conditions on road surface by simulating load, because test specimen can provide enough confined pressures during test.Yet, consider nominal maximum aggregate size in test specimen, i.e. the size effect of particle diameter and pressure head, pressure head again can not be too little, otherwise test figure there will be larger variability.Pressure head, base and the sample dimensions parameter of local triaxial test should meet following two conditions:

(1) even for meeting ess-strain: S _mises| _r=d/2substantially even, i.e. S _mises| _r=d/2place decays to less.

(2) for enough confined pressures: σ is provided ₃₃| _r=D/2go to zero, S _mises| _r=D/2decayed to enough littlely, level is to regarding infinitely great as.

Wherein: σ ₃₃for normal stress radially; $S_{\mathrm{Mises}}=\sqrt{\frac{1}{2}[{({\mathrm{\&sigma;}}_1-{\mathrm{\&sigma;}}_2)}^2+{({\mathrm{\&sigma;}}_2-{\mathrm{\&sigma;}}_3)}^2+{({\mathrm{\&sigma;}}_3-{\mathrm{\&sigma;}}_1)}^2]}$ Be called Mises stress, σ _ifor principle stress, i=1,2,3.

Along with the increase of pressure head diameter, Mises stress distribution scope is increasing.In order to keep along radial direction, substantially even from 0 to d/2 scope internal stress, necessarily require in the stress decay at r=d/2 place less; For enough confined pressures are provided, at the Mises of edge (r=D/2) of test specimen stress, should decay to enough little simultaneously.

In addition, also can be by increasing uniaxial compression test and drawing the coulomb Mohrcircle of asphalt in conjunction with three axle penetration tests, as shown in Figure 1,2,3, 4.In actual test, adopt the test specimen of φ 100mm * H100mm to carry out unconfined compression test.

By Fig. 4, we derive by simple geometric relationship, and the relation that can derive side force P and C, φ is as follows:

$\frac{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="DEST\_PATH\_HDA0000440410130000041.png,DEST\_PATH\_HDA0000440410130000062.png"\; state="\{\{state\}\}">P</figure-callout>}}{2}\&CenterDot;\cos \mathrm{\&phi;}=C+(\frac{P}{2}-\frac{\mathrm{<figure-callout\; id="2"\; label="P"\; filenames="DEST\_PATH\_HDA0000440410130000041.png,DEST\_PATH\_HDA0000440410130000062.png"\; state="\{\{state\}\}">P</figure-callout>}}{2}\sin \mathrm{\&phi;})\&CenterDot;\tan \mathrm{\&phi;}---\left(2\right)$

(1) formula is simplified:

$P=2C\&CenterDot;\sqrt{\frac{1+\sin \mathrm{\&phi;}}{1-\sin \mathrm{\&phi;}}}---\left(3\right)$

In addition, owing to supposing not consider gravity and other power of asphalt, therefore, for the force mode that is subject to of Fig. 1, can think three axle stress models.By Mohrcircle, as shown in Figure 5, can release the computing formula of its three axle when stressed, as follows.

$F-P=\frac{2P\sin \mathrm{\&phi;}}{1-\sin \mathrm{\&phi;}}+2C\&CenterDot;\sqrt{\frac{1+\sin \mathrm{\&phi;}}{1-\sin \mathrm{\&phi;}}}---\left(4\right)$

Now, side force (3) formula substitution (4) formula is obtained:

$F=\frac{4C}{1-\sin \mathrm{\&phi;}}\sqrt{\frac{1+\sin \mathrm{\&phi;}}{1-\sin \mathrm{\&phi;}}}---\left(5\right)$

(4) F of formula can obtain by local triaxial test.Therefore,, by (3) and (5) formula, can obtain:

$\left\{\begin{array}{c}C=\frac{P}{2}\sqrt{\frac{P}{F-P}}\\ \mathrm{\&phi;}=\arcsin (1-\frac{2P}{F})\end{array}\right.---\left(6\right)$

The cohesion that C in above formula (2)-(6) is asphalt mixture; The side force that P provides for asphalt, can be obtained by unconfined compression test; φ is asphalt Nei Mocha angle; F is the vertical force applying, and can obtain by local triaxial test.

Therefore, the contrast of triaxial test and local triaxial test: while test specimen being applied to confined pressure in triaxial test, need three axle confined pressure chambers, to having relatively high expectations of instrument, and it is more difficult to measure test specimen radial deformation; And local triaxial test only need load and displacement measuring device.In addition, triaxial test step is comparatively loaded down with trivial details, as test specimen is made, need unbearable cutting etc., on test operation, need to wrap up test specimen and test in the water-bath of steady temperature with latex film, regulate water temperature complex steps and wayward, triaxial chamber still needs the air bath of steady temperature outward; And the making of the test specimen of local triaxial test is relatively simple, test specimen only need be incubated and can test in the air bath of steady temperature.The most important thing is that local triaxial test can access approaches actual pavement destruction state parameter.

Beneficial effect: in conjunction with the advantage of triaxial test and uniaxial penetration test, the new test method (local triaxial test) that the present invention adopts utilizes the compound of pressure head periphery that the confined pressure of variation can be provided, can simulate well actual road surface situation, with the more realistic road surface of triaxial compression test contrast situation.Local triaxial test tool has the following advantages: (1) can simulate actual road surface side to constraint condition, when test specimen is carried out to local loading, compound beyond pressure head forms effect of contraction to loading the compound of pressure head bottom, and this effect of contraction can change with mix type, temperature and stress level, can simulate the effect of contraction on actual road surface, with this, replace artificial fixing lateral restriction; (2) similar triaxial test, has advantages of as clearly in triaxial test stress state, can measure some strain regimes, has again uniaxial penetration test that the advantage of the actual confined pressure in similar road surface is provided; (3) ess-strain is substantially even, can calculate strain by measuring simply distortion; (4) the test specimen failure mode in local triaxial test and actual pavement destruction similar in form, therefore, this test method can effectively be simulated actual pavement state; (5) from aspects such as test specimen making, testing equipment and operation stepss, local triaxial test is simple more than triaxial compression test, is beneficial to popularization.

The present invention proposes partial triaxial test and radial displacement proving installation, can be used for bituminous pavement shearing performance test, can simulate the actual road surface changing with mix type, temperature and stress level, and having provided corresponding test method, principle, operation steps etc., this test method and device thereof have good generalization and novelty.

Accompanying drawing explanation

Fig. 1,2,3,4 makes the stressed schematic diagram of used time two dimension for the semi-infinite space is subject to Circular Loading;

Fig. 5 is triaxial test Mohrcircle force analysis figure;

Fig. 6 is radial displacement proving installation structural representation of the present invention;

Fig. 7 is the front view (FV) of radial displacement proving installation middle pulley of the present invention;

Fig. 8 is that closed chain of the present invention is taken over sectional view;

Fig. 9 is radially front view (FV) of the single pulley of the present invention;

Figure 10 is the single pulley radial section of the present invention figure;

Figure 11 is a pair of pulley sectional view of the present invention;

Figure 12 is adjusting bolt stationary installation sectional view of the present invention;

Figure 13 is Linear displacement transducer stationary installation sectional view of the present invention.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention will be further described.

As shown in Fig. 6-13, a radial displacement proving installation, comprises closed chain adapter 1, pulley 2, spring 3, adjusting bolt 4, adjusting bolt stationary installation 5, fixed screw 1, fixed screw 27, Linear displacement transducer stationary installation 8 and Linear displacement transducer 9, described closed chain is taken over 1 and is connected with pulley 2 by steel bar 14, form the chain clamp of an opening, in this fixture, be provided with cylindrical bitumen mixture specimen, the two ends of described fixture are separately installed with adjusting bolt stationary installation 5 and Linear displacement transducer stationary installation 8, adjusting bolt stationary installation 5 with in Linear displacement transducer stationary installation 8, be respectively equipped with the relative hole in position, described adjusting bolt 4 and Linear displacement transducer 9 are positioned over respectively in above-mentioned two holes, adjusting bolt 4 smooth end are smooth, and with smooth contact the in Linear displacement transducer 9 tops, adjusting bolt 4 is provided with fixed screw 1, Linear displacement transducer 9 is provided with fixed screw 27, the opening two ends of described fixture are connected with spring 3, described pulley 2 comprises interior ring 11 and outer shroud 12, between interior ring 11 and interior ring 12, is provided with ball 13.Described closed chain is taken over 1 and is provided with the circular hole 10 that facilitates steel bar 14 to pass.Described Linear displacement transducer 9 adopts the high-accuracy linear displacement sensor of UTM configuration.

An asphalt partial triaxial test that adopts above-mentioned radial displacement proving installation, comprises the following steps:

1) test specimen is placed in to environmental chamber insulation at least 4 hours, makes it be stabilized to the test temperature of regulation;

2), after temperature stabilization, test specimen is installed; Adopt two equal pressure heads of size respectively local restriction to be carried out in test specimen two ends, make the compound regional stress between push-down head relatively even, and the pressure head on test specimen top is carried out to local loading, the compound of pressure head periphery can provide the confined pressure of variation; Test specimen is placed on bearing, and load applies by being less than the pressure head of test specimen diameter, and two LVDT are arranged on the pressure head of test specimen top end face, to measure axial strain; Radial displacement proving installation is installed at test specimen middle part, and installation steps are as follows: (1) measures test specimen, and on the middle section of test specimen, setting-out is marked; (2) will be radially test fixture be arranged on test specimen, installation site should be the middle section of test specimen, to avoid the impact of end restraint, and adjusts the center line of fixture and the mark line of test specimen overlaps, to guarantee that fixture is in the surface level perpendicular to test specimen central shaft; (3) test specimen is put under the loading pressure head of UTM, and be adjusted to center; (4) radial displacement transducer LVDT is put in hoop test fixture, adjust its initial value to correct position, tighten the screws fixation of sensor; (5) prepare test, to measure radial strain, measurement range: 0～50mm; For prevent base and pressure head to the restrictions of the frictional force of test specimen the distortion of test specimen, between test specimen and pressure head, base, place double-deck latex film, between latex film, be coated with railway grease, ensure test specimen end face Free Transform;

3) whether normal tune-up data test and acquisition system, detect LVDT reaction, and adjust LVDT to the beginning of line style scope, so that gamut is all effective to accumulation of distortion;

4) close environmental chamber time enough 10 to 15 minutes, make the temperature of test specimen and environmental chamber reach stable;

5) be incubated to test temperature, test specimen is applied to pre-constant load, loading speed is got 1mm/min;

6) test result analysis.

It should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.In the present embodiment not clear and definite each ingredient all available prior art realized.

Claims (7)

1. a radial displacement proving installation, is characterized in that: comprise closed chain adapter, pulley, spring, adjusting bolt, adjusting bolt stationary installation, fixed screw one, fixed screw two, Linear displacement transducer stationary installation and Linear displacement transducer;

Described closed chain is taken over and is connected with pulley by steel bar, form the chain clamp of an opening, in this fixture, be provided with cylindrical bitumen mixture specimen, the two ends of described fixture are separately installed with adjusting bolt stationary installation and Linear displacement transducer stationary installation, adjusting bolt stationary installation with in Linear displacement transducer stationary installation, be respectively equipped with the relative hole in position, described adjusting bolt and Linear displacement transducer are positioned over respectively in above-mentioned two holes, adjusting bolt smooth end is smooth, and contact with Linear displacement transducer top is smooth, adjusting bolt is provided with fixed screw one, Linear displacement transducer is provided with fixed screw two, the opening two ends of described fixture are connected with spring, described pulley comprises interior ring and outer shroud, between interior ring and interior ring, is provided with ball.

2. radial displacement proving installation according to claim 1, is characterized in that: described closed chain is taken over and is provided with the circular hole that facilitates steel bar to pass.

3. radial displacement proving installation according to claim 1, is characterized in that: described Linear displacement transducer adopts the high-accuracy linear displacement sensor of UTM-25 multifunctional material system configuration.

4. an asphalt partial triaxial test that adopts claim 1 radial displacement proving installation, is characterized in that: comprise the following steps:

1) test specimen is placed in to environmental chamber insulation at least 4 hours, makes it be stabilized to the test temperature of regulation;

2), after temperature stabilization, test specimen is installed; Adopt two equal pressure heads of size respectively local restriction to be carried out in test specimen two ends, make the compound regional stress between push-down head relatively even, and the pressure head on test specimen top is carried out to local loading, the compound of pressure head periphery can provide the confined pressure of variation; Test specimen is placed on bearing, and load applies by being less than the pressure head of test specimen diameter, and two LVDT are arranged on the pressure head of test specimen top end face, to measure axial strain; Radial displacement proving installation is installed at test specimen middle part, and installation steps are as follows: (1) measures test specimen, and on the middle section of test specimen, setting-out is marked; (2) will be radially test fixture be arranged on test specimen, installation site should be the middle section of test specimen, to avoid the impact of end restraint, and adjusts the center line of fixture and the mark line of test specimen overlaps, to guarantee that fixture is in the surface level perpendicular to test specimen central shaft; (3) test specimen is put under the loading pressure head of UTM, and be adjusted to center; (4) radial displacement transducer LVDT is put in hoop test fixture, adjust its initial value to correct position, tighten the screws fixation of sensor; (5) prepare test, to measure radial strain, measurement range: 0～50mm;

3) whether normal tune-up data test and acquisition system, detect LVDT reaction, and adjust LVDT to the beginning of line style scope, so that gamut is all effective to accumulation of distortion;

4) close environmental chamber time enough, make the temperature of test specimen and environmental chamber reach stable;

5) be incubated to test temperature, test specimen is applied to pre-constant load;

6) test result analysis.

5. asphalt partial triaxial test according to claim 4, it is characterized in that: above-mentioned steps 2) for prevent base and pressure head to the restrictions of the frictional force of test specimen the distortion of test specimen, between test specimen and pressure head, base, place double-deck latex film, between latex film, be coated with railway grease, ensure test specimen end face Free Transform.

6. asphalt partial triaxial test according to claim 4, is characterized in that: above-mentioned steps 4), closing environmental chamber time enough is 10 to 15 minutes.

7. asphalt partial triaxial test according to claim 4, is characterized in that: the loading speed that above-mentioned steps 5), test specimen is applied to pre-constant load is got 1mm/min.

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