CN204495322U - Asphalt creep test radial strain real-time test device - Google Patents

Abstract

The utility model discloses asphalt creep test radial strain real-time test device, comprise and be connected on the several of surface of test piece with AB is gluing measuring point is followed closely, every a pair measuring point nail is radial to be placed, and sensor stationary fixture is enclosed within measuring point and nails on, and clamps LVDT sensor between two sensor stationary fixtures.Sensor interface Real-time Collection LVDT sensor 4 deformation data of SPT standard configuration is coordinated in measuring process, and then utilize the utility model computing method to derive the real-time radial deformation of each section of test specimen 1, test result can be used for the anti-rut behavior of thoroughly evaluating asphalt, and the permanent strain also produced under load repeat function for asphalt (rut disease) study mechanism provides required Data support.

Description

Asphalt creep test radial strain real-time test device

Technical field

The utility model belongs to road engineering technical field, relates to asphalt creep test radial strain real-time test device.

Background technology

Rut is one of main disease form of bituminous pavement, the aspects such as the travel safety during road pavement builds up operation, comfortableness and aesthetic property have material impact, the maintenance process of rut disease also occupies the road maintenance maintenance cost expenditure of suitable vast scale, reaches more than 50%.In China, bituminous pavement generally adopts semi-rigid asphalt pavement, pavement track can the permanent deformation resistance of no generation, order of severity asphalt how used with making bituminous pavement closely related.The power of asphalt permanent deformation resistance has vital effect for bituminous pavement opposing rut disease.

For obtaining the good asphalt of rutting resistance, a large amount of Test model synthetic techniques of software engineering researchers invent, traditional as Marshall method, rut test method, static load creep test method, novel load creep test method as repeated, etc.In these methods, traditional evaluation method due to test process not corresponding with the virtual condition that pavement track produces, only can the ability of lateral comparison different pitches compound opposing rutting deformation, but mechanism of production and the rule of development of pavement structure rut disease under Vehicle Load cannot be described.

Repeat to load creep test method to be developed by American Highway joint study tissue (NCHRP), the method applies to repeat dynamic loads on cylindrical bitumen mixture specimen, vehicular load is simulated in actual road surface to the repeat function of bituminous pavement with this, by measuring axis (vertically) distortion of asphalt, the rutting resistance of asphalt is described with the number of loading (being called flowing number) that the minimum axial direction rate of strain of asphalt is corresponding.Repeating to load creep test method can at the proving installation of standard (the simple Performance Test System of asphalt, Simpleperformance Tester, SPT) complete on, the test conditions such as different temperature, confined pressure, load level can be set, due to process of the test conform to road surface virtual condition, the advantage such as data testing accuracy is high, evaluation result is reasonable, worldwide obtain extensive accreditation, domestic relevant research institution is a considerable amount of testing apparatus of proportioning also.

But, the repeated creep test carried out on SPT at present, its standard test fixture only can obtain axis (vertically) distortion of asphalt under Repeated Loading, radial direction (transverse direction) distortion of process of the test Asphalt Mixture cannot be obtained, directive significance for asphalt mixture material design is not enough, also cannot provide how effective information for the permanent strain mechanism of asphalt and rule of development research.Can asphalt shedder overstock contracting or volumetric expansion such as, in the process of the test that scientific research personnel is concerned about? if occur, appear at which kind of stage? this needs the integrated data learning axis and radial deformation to determine.The further investigation of this drawbacks limit to asphalt mixture shearing flow deformation Analysis on Mechanism.

For the defect of this method of testing, the people such as Nelson Gibson have carried out improvement, adopt digital imaging technology, while SPT carries out repeated creep test, high-definition digital video camera is utilized to carry out imaging to radial deformation, and then utilize MATLAB software programming that digital photos is converted into deformation data, obtain the strain data of asphalt three-dimensional thus.The method technical feasibility, but there is following major defect: (1) digital imaging system is expensive, and due to the light refraction of test specimen environment storehouse cloche and scattering, need to be equipped with special imaging background and light source, otherwise cannot obtain effective digital photos, this facility is also higher to the requirement of experimental enviroment; (2) the method cannot realize axial deformation and gathers with synchronous (in real time) of radial deformation, and need a large amount of artificial treatment in later stage, workload is large; (3) equipment installation site, crevice projection angle etc. all need to fix, and need the special purpose computer being equipped with process digital photos, take up room and have enough to meet the need inconvenience.

Utility model content

The purpose of this utility model is providing asphalt creep test radial strain real-time test device, solve axis (vertically) distortion that current standard test fixture only can obtain asphalt under Repeated Loading, the problem that the radial direction (transverse direction) that cannot obtain process of the test Asphalt Mixture is out of shape.

The technical scheme that the utility model asphalt creep test radial strain real-time test device adopts comprises being connected on the several of surface of test piece following closely measuring point with AB being gluing, every a pair measuring point nail is radial to be placed, sensor stationary fixture is enclosed within measuring point and nails on, and clamps LVDT sensor between two sensor stationary fixtures.

Further, described test specimen is diameter 100mm, the standard asphalt compound test specimen of high 150mm.

Further, described measuring point nail is positive hexagon, diameter 10mm, high 15mm.

Further, described sensor stationary fixture is made up of two V-type fixed sturctures and two linking springs, the V-type opening confront crosswise of two V-type fixed sturctures is placed, forming middle part is the shape that positive six prismatic mouth, V-type both wings two ends intersect, infall is rotatably connected, the two ends opposite side intersected is provided with hole, and the two ends of spring are arranged in hole respectively, and the V-type top of V-type fixed sturcture is provided with hemispherical groove.

Further, described LVDT sensor selection standard LVDT sensor, long 20mm, steel pipe encapsulates.

The beneficial effect of this utility model is based on SPT pilot system, realizes real-time synchronization that is axial in process of the test, radial deformation and measures.

Accompanying drawing explanation

Fig. 1 is strain transducer and the assembly drawing of fixture on bitumen mixture specimen;

Radial section schematic diagram when Fig. 2 is test specimen test;

Fig. 3 is steel measuring point pin structure skeleton view;

Fig. 4 is sensor stationary fixture sectional view;

Fig. 5 is that bitumen mixture specimen radial strain calculates schematic diagram.

In figure, 1. test specimen, 2. measuring point nail, 3. sensor stationary fixture, 4.LVDT sensor, 301.V type fixed sturcture, 302. springs, 303. hemispherical groove.

Embodiment

Below in conjunction with the drawings and specific embodiments, the utility model is described in detail.

The utility model can the device of radial strain in Real-Time Monitoring asphalt repeated creep test process, be strain transducer and the assembly drawing of fixture on bitumen mixture specimen as depicted in figs. 1 and 2, the several to measuring point nail 2 of test specimen 1 surface are connected on AB is gluing, every a pair measuring point nail 2 is radial to be placed, sensor stationary fixture 3 is enclosed within measuring point nail 2, clamps LVDT sensor 4 between two sensor stationary fixtures 3.

This device is in the upper use of asphalt simple performance experiment system (SPT), the surface of standard asphalt compound test specimen 1 differing heights of diameter 100mm × high 150mm can be fixed on, sensor interface Real-time Collection LVDT sensor 4 deformation data of SPT standard configuration is coordinated in measuring process, and then utilize the utility model computing method to derive the real-time radial deformation of each section of test specimen 1, test result can be used for the anti-rut behavior of thoroughly evaluating asphalt, also permanent strain (rut disease) study mechanism produced under load repeat function for asphalt provides required Data support.

Asphalt repeated creep test radial strain real-time test device based on SPT of the present utility model, this device every suit comprises two steel measuring point nail 2, two sensor stationary fixtures 3 and 1 standard LVDT displacement transducer 4; As shown in Figure 3, steel measuring point nail 2 be positive hexagon, diameter 10mm × high 15mm, utilizes that AB is gluing is connected on test specimen 1 surface, for locating and placement sensor stationary fixture 3;

As shown in Figure 4, sensor stationary fixture 3 overall dimensions be 10mm thick × 20mm is wide × 30mm is high, be made up of 2 linking springs 302 and 2 steel V-type fixed sturctures 301, two V-type fixed sturcture 301 subtends are settled, both wings are all with hole, for laying linking springs 302, V-type fixed sturcture 301 top is with hemispherical groove 303, and 2 sensor stationary fixtures 3 can locate LVDT sensor 4;

The long 20mm of standard LVDT sensor 4, steel pipe encapsulates, and the standard interface being out of shape acquisition system with SPT is connected.Apply this device and can monitor the overall process that asphalt repeats to load certain cross-section radial distortion in creep test process, if 3 cover or number cover with the use of, then can obtain the radial deformation Changing Pattern testing omnidistance Asphalt Mixture test specimen arbitrary section, the rule of development of asphalt mixture volume distortion from the different load phase of acquisition, for the permanent strain study mechanism of asphalt provides required basic data.

As shown in Figure 5, the bitumen mixture specimen radial strain computing method based on this proving installation are: set bitumen mixture specimen 1 radius as r (standard radius is 50mm); Sensor stationary fixture 3 length is 2a, and its mid-depth point is A, is d with the distance on test specimen 1 surface; LVDT sensor 4 is long is 2l, central point is B, sensor stationary fixture 3 is C with the intersection point of LVDT sensor 4 end, the center being in conplane test specimen 1 with LVDT sensor 4 is O, the angle of cut of line segment OC and OA, OB is respectively α, β, then utilize basic triangle relation to derive to utilize the test specimen radius of above Parametric Representation if when the radius when certain cross section of test specimen in process of the test 1 increases to (r+ Δ r), the length variations of LVDT sensor 4 is Δ l, because LVDT sensor 4 length is very little compared with test specimen 1 radius, the change of angle beta can be ignored, so the computing formula that can obtain test specimen 1 radial strain is the real-time area that also can calculate test specimen 1 cross section is $S=\mathrm{\π}{(\sqrt{\frac{{(l+\mathrm{\Δl})}^2}{{\sin }^2\mathrm{\β}}-a^2}-d)}^2.$

Because process of the test bitumen mixture specimen 1 axial strain Changing Pattern can be gathered automatically by SPT system, when supporting the use many covers (3 covers and more than) proving installation of the present utility model and radial strain computing method, can further by polynomial fitting method, obtain axial, the radial strain change curve of the whole height of test specimen, thus obtain the Changing Pattern of test overall process Asphalt Mixture cubic deformation.

The utility model is based on SPT pilot system, for standard weight be added with carry creep test only can measure axial strain, cannot the shortcoming of Simultaneous Determination test specimen radial deformation, devise radial deformation data real time acquisition device, and propose computing method, coordinate the axial deformation harvester that SPT carries, achieve real-time synchronization that is axial in process of the test, radial deformation to measure, can be used for the anti-rut behavior evaluating asphalt, the Analysis on Mechanism that also can be Bitumen Mixture Permanent Deformation provides required basic data support.Test fixture advantages of simple, the test operation process of the utility model design are simple, the computing method clear concept of proposition, solve classic method support equipment complicated, cannot the defects such as synchronization gain test data, Data Post be loaded down with trivial details, there is theory and actual application value.

The above is only to better embodiment of the present utility model, not any pro forma restriction is done to the utility model, every any simple modification above embodiment done according to technical spirit of the present utility model, equivalent variations and modification, all belong in the scope of technical solutions of the utility model.

Claims (5)

1. asphalt creep test radial strain real-time test device, it is characterized in that: comprise and be connected on the several to measuring point nail (2) of test specimen (1) surface with AB is gluing, every a pair measuring point nail (2) radial direction is placed, sensor stationary fixture (3) is enclosed within measuring point nail (2), clamps LVDT sensor (4) between two sensor stationary fixtures (3).

2. according to asphalt creep test radial strain real-time test device described in claim 1, it is characterized in that: described test specimen (1) is the standard asphalt compound test specimen of diameter 100mm, high 150mm.

3. according to asphalt creep test radial strain real-time test device described in claim 1, it is characterized in that: described measuring point nail (2) is positive hexagon, diameter 10mm, high 15mm.

4. according to asphalt creep test radial strain real-time test device described in claim 1, it is characterized in that: described sensor stationary fixture (3) is made up of two V-type fixed sturctures (301) and two linking springs (302), the V-type opening confront crosswise of two V-type fixed sturctures (301) is placed, forming middle part is positive six prismatic mouths, the shape that V-type both wings two ends intersect, infall is rotatably connected, the two ends opposite side intersected is provided with hole, the two ends of spring (302) are arranged in hole respectively, the V-type top of V-type fixed sturcture (301) is provided with hemispherical groove (303).

5. according to asphalt creep test radial strain real-time test device described in claim 1, it is characterized in that: described LVDT sensor (4) selection standard LVDT sensor, long 20mm, steel pipe encapsulates.