CN104198587A - Method for measuring damage evolution of concrete material under action of static load - Google Patents

Abstract

The invention discloses a method for measuring damage evolution of a concrete material under action of static load. The method has the advantages of being capable of measuring the damage evolution law of the concrete material under different load conditions, obtaining correct measurement results, and achieving extensive practical engineering applicability and theoretical value; besides, instrument equipment used in the method is simple and operation is simple and convenient.

Description

Concrete material damages the measuring method developing under static load effect

Technical field

The damage evolution that the present invention relates to concrete material is measured, and relates in particular to concrete material and under static load effect, damages the measuring method developing.

Background technology

In engineering, concrete is a kind of application structured material very widely at present, and it is used in a large number at covil construction, road and bridge, military blindage, nuclear facilities, offshore platform etc.Concrete material in process, is mainly subject to the effect of static load under arms.Under static load effect, concrete material inside inevitably has damage and forms and be accompanied by damage evolution.And the damage Evolution of concrete material is the basis that builds concrete material constitutive relation and concrete facility is carried out to security monitoring, but also concrete material is not damaged under static load effect the measuring method developing at present.

Summary of the invention

Technical matters to be solved by this invention is to provide a kind of concrete material and under static load effect, damages the measuring method developing.

The present invention solves the problems of the technologies described above adopted technical scheme: concrete material damages the measuring method developing under static load effect, comprises following concrete steps:

(1), according to concrete mix-design, manufactured size is the concrete standard test specimen of 150mm * 150mm * 150mm, and the concrete standard test specimen of making is carried out to standard curing, standard curing condition is: 20 ± 2 ℃ of curing temperatures, humidity more than 95%, 28 days time;

(2), any one group of opposite planar in selected concrete standard test specimen, therein in a plane, at least two measuring points of fetch bit on this plane diagonal line, be designated as measuring point 1,2 ... m, m >=2 and round numbers, again in opposite planar with measuring point 1,2 ... m gets measuring point in corresponding position, and is designated as measuring point 1 ', 2 ' ... m ';

(3), the transducer in nonmetal ultrasonic detector and main frame are connected firmly, stablize, and according to the size of concrete standard test specimen, the emitting voltage of setting nonmetal ultrasonic detector is 1000V, sampling period to be the wide 0.08ms of being of 0.4ms, transmitted wave;

(4), the wherein one group of opposite planar that selected and measuring point place plane is perpendicular is as imposed load face, and one of them plane contacted with ground or work top level, applies successively respectively different static load P in opposite planar ₀, P ₁p _n, n round numbers, wherein P ₀=0, P _n≤ σ S, σ is concrete material mix-design intensity, S is the loading end area of concrete standard test specimen;

(5), when the suffered static load of concrete standard test specimen is P ₀time, even daubing coupling agent on the transducer of nonmetal ultrasonic detector, and the perpendicular direction of the transmitting terminal edge of transducer and measuring point 1 place plane is fixed on measuring point 1, the direction that the receiving end edge of transducer and measuring point 1 ' place plane is perpendicular is fixed on measuring point 1 ', measuring the ultrasound wave longitudinal wave velocity of measuring point 1, is C ₀₁, then according to identical operation, measure successively measuring point 2 ... the ultrasound wave longitudinal wave velocity of m, is designated as C ₀₂c _0m;

(6), when the suffered static load of concrete standard test specimen is respectively P ₁p _ntime, according to the operation of step (5), respectively each measuring point on concrete standard test specimen is carried out to ultrasound examination, and record the measuring point 1,2 of concrete standard test specimen under corresponding static load ... the ultrasound wave longitudinal wave velocity at m place, is designated as: C ₁₁, C ₁₂c _1m..., C _n1, C _n2c _nm, then obtain respectively corresponding static load P ₀, P ₁p _nthe mean value of the ultrasound wave longitudinal wave velocity of lower concrete standard test specimen, is designated as C ₀, C ₁c _n, wherein: $C_0=\frac{C_{01}+C_{02}+...+C_{0m}}{m},C_1=\frac{C_{11}+C_{12}+...+C_{1m}}{m},...,$ $C_n=\frac{C_{n1}+C_{n2}+...+C_{\mathrm{nm}}}{m};$

(7), by the mean value C of the ultrasound wave longitudinal wave velocity of concrete standard test specimen under the different static load effects that obtain ₀, C ₁c _nthe injuring relation formula of difference substitution concrete material in, wherein: k=0,1,2 ... n, obtains the impairment value D of corresponding concrete standard test specimen under different static loads ₀, D ₁d _n, then with the stress value of the concrete standard test specimen under different static load effects for horizontal ordinate, with the impairment value D of corresponding concrete standard test specimen under corresponding stress state ₀, D ₁d _nfor ordinate, with MATLAB mathematical software, carry out the data fitting of B batten, obtain the cubic B-spline smooth curve of stress-damage function, just obtains the damage Evolution of concrete material under static load effect.

In described step (2), measuring point is 3 and divides equally on the diagonal line that is distributed in plane.

Compared with prior art, advantage of the present invention is the damage Evolution that the method can be measured concrete material in different loads situation, and measurement result is more accurate, has practical engineering application and theory value widely; And the instrument and equipment using in method is simple, simple to operation.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of the loading surface on concrete standard test specimen and test surfaces in the present invention;

Fig. 2 is the damage Evolution of the measured concrete material obtaining of the present invention.

Embodiment

Below in conjunction with accompanying drawing, embodiment is described in further detail the present invention.

As shown in the figure, concrete material damages the measuring method developing under static load effect, comprises following concrete steps:

(1), according to concrete mix-design, manufactured size is the concrete standard test specimen of 150mm * 150mm * 150mm, and the concrete standard test specimen of making is carried out to standard curing, standard curing condition is: 20 ± 2 ℃ of curing temperatures, humidity more than 95%, 28 days time;

(2), one group of the front and back opposite planar in selected concrete standard test specimen, on frontal plane, get three measuring points that are evenly distributed on this plane diagonal line, be designated as measuring point 1,2,3, on back plane, measuring point is got in the position corresponding with measuring point 1,2,3 again, and is designated as measuring point 1 ', 2 ', 3 ';

(3), the transducer in nonmetal ultrasonic detector and main frame are connected firmly, stablize, and according to the size of concrete standard test specimen, the emitting voltage of setting nonmetal ultrasonic detector is 1000V, sampling period to be the wide 0.08ms of being of 0.4ms, transmitted wave;

(4), selected and measuring point place plane perpendicular upper next organize opposite planar as imposed load face, and lower plane is contacted with work top level, in upper plane, apply successively respectively different static load 0kN, 100kN, 200kN, 300kN, 400kN, 500kN, 600kN, the mix-design intensity σ of concrete material is 30MPa, and the loading end area S of concrete standard test specimen is 0.0225m ²;

(5), when the suffered static load of concrete standard test specimen is 0kN, even daubing coupling agent on the transducer of nonmetal ultrasonic detector, and the perpendicular direction of the transmitting terminal edge of transducer and measuring point 1 place plane is fixed on measuring point 1, the direction that the receiving end edge of transducer and measuring point 1 ' place plane is perpendicular is fixed on measuring point 1 ', measure the ultrasound wave longitudinal wave velocity 4.624km/s of measuring point 1, the ultrasound wave longitudinal wave velocity of then measuring successively measuring point 2,3 according to identical operation is respectively 4.639km/s, 4.652km/s;

(6), when the suffered static load of concrete standard test specimen is respectively 100kN, 200kN, 300kN, 400kN, 500kN, during 600kN, according to the operation of step (5), respectively each measuring point on concrete standard test specimen is carried out to ultrasound examination, and record the measuring point 1 of concrete standard test specimen under corresponding static load, 2, the ultrasound wave longitudinal wave velocity at 3 places, be respectively: 4.416km/s, 4.447km/s, 4.433km/s, 4.122km/s, 4.198km/s, 4.164km/s, 3.746km/s, 3.761km/s, 3.785km/s, 3.248km/s, 3.268km/s, 3.275km/s, 2.657km/s, 2.690km/s, 2.635km/s, 1.935km/s, 1.949km/s, 1.925km/s, then obtain respectively the mean value of the ultrasound wave longitudinal wave velocity of concrete standard test specimen under corresponding static load, be respectively: 4.638km/s, 4.432km/s, 4.161km/s, 3.746km/s, 3.264km/s, 2.661km/s, 1.936km/s,

(7), by the injuring relation formula of mean value 4.638km/s, the 4.432km/s of the ultrasound wave longitudinal wave velocity of concrete standard test specimen under the different static load effects that obtain, 4.161km/s, 3.746km/s, 3.264km/s, 2.661km/s, 1.936km/s difference substitution concrete material in, wherein: k=0,1,2 ... 7, obtain the impairment value 0,0.0869,0.1951,0.3414,0.5047,0.6708,0.8258 of corresponding concrete standard test specimen under different static loads, then stress value 0MPa, 4.444MPa, 8.888MPa, 13.333MPa, 17.778MPa, 22.222MPa, the 26.667MPa of the concrete standard test specimen under different static load effects of take is horizontal ordinate, the impairment value of corresponding concrete standard test specimen under corresponding stress state of take is ordinate, the data fitting of carrying out B batten with MATLAB mathematical software, obtains the cubic B-spline smooth curve of stress-damage function, just obtains the damage Evolution of concrete material under static load effect.

Be below the derivation to the injuring relation formula of concrete material, it is basis that < < theory of stress wave > >, < < damage mechanics > > material are take in this derivation:

Ultrasound wave is propagated in concrete medium by three kinds of forms, compressional wave, shear wave and surface wave, and vertical velocity of wave propagation is the fastest, therefore this method is mainly studied the propagation law of compressional wave in concrete material.Suppose that concrete material is uniform dielectric, so its dynamic elastic modulus E _dwith the longitudinal wave velocity C propagating therein ₁relation can represent with following formula:

$C_1=\sqrt{\frac{E_d(1-\mathrm{\&nu;})}{\mathrm{\&rho;}(1-2\mathrm{\&nu;})(1+\mathrm{\&nu;})}}---\left(1\right),$

Wherein: E _dfor the dynamic modulus of elasticity of concrete material, C ₁for the longitudinal wave velocity of propagating in concrete, the density that ρ is concrete material, the Poisson ratio that ν is concrete material.

Thereby can obtain the initial velocity of wave E in concrete material ₀, wherein: C ₀for the initial longitudinal wave velocity of propagating in concrete, ρ ₀for the initial density of concrete material, ν ₀initial Poisson ratio for concrete material, and concrete material is in being subject to static load process, the density of this research supposition concrete material is constant, and effects of Poisson's ratio is little on the impact of concrete damage, the damage evolution of concrete in being subject to static load process just shows as the evolution of concrete dynamic modulus of elasticity so, if concrete is subject in static load process, the impairment value that concrete is caused is D, can draw: $C=\sqrt{\frac{E_0(1-D)(1-{\mathrm{\&nu;}}_0)}{{\mathrm{\&rho;}}_0(1-{2\mathrm{\&nu;}}_0)(1+{\mathrm{\&nu;}}_0)}}---\left(3\right)$

(2) formula substitution (3) formula, just can draw the relational expression of concrete impairment value D:

$D=1-{\left(\frac{C}{C_0}\right)}^2---\left(4\right)$

Wherein: C ₀for the initial longitudinal wave velocity of propagating in concrete, C be concrete in different static load situations, the ultrasound wave longitudinal wave velocity of propagating in concrete material.

Claims (2)

1. concrete material damages the measuring method developing under static load effect, it is characterized in that comprising following concrete steps:

(1), according to concrete mix-design, manufactured size is the concrete standard test specimen of 150mm * 150mm * 150mm, and the concrete standard test specimen of making is carried out to standard curing, standard curing condition is: 20 ± 2 ℃ of curing temperatures, humidity more than 95%, 28 days time;

(2), any one group of opposite planar in selected concrete standard test specimen, therein in a plane, at least two measuring points of fetch bit on this plane diagonal line, be designated as measuring point 1,2 ... m, m >=2 and round numbers, again in opposite planar with measuring point 1,2 ... m gets measuring point in corresponding position, and is designated as measuring point 1 ', 2 ' ... m ';

(3), the transducer in nonmetal ultrasonic detector and main frame are connected firmly, stablize, and according to the size of concrete standard test specimen, the emitting voltage of setting nonmetal ultrasonic detector is 1000V, sampling period to be the wide 0.08ms of being of 0.4ms, transmitted wave;

(4), the wherein one group of opposite planar that selected and measuring point place plane is perpendicular is as imposed load face, and one of them plane contacted with ground or work top level, applies successively respectively different static load P in opposite planar ₀, P ₁p _n, n round numbers, wherein P ₀=0, P _n≤ σ S, σ is concrete material mix-design intensity, S is the loading end area of concrete standard test specimen;

(5), when the suffered static load of concrete standard test specimen is P ₀time, even daubing coupling agent on the transducer of nonmetal ultrasonic detector, and the perpendicular direction of the transmitting terminal edge of transducer and measuring point 1 place plane is fixed on measuring point 1, the direction that the receiving end edge of transducer and measuring point 1 ' place plane is perpendicular is fixed on measuring point 1 ', measuring the ultrasound wave longitudinal wave velocity of measuring point 1, is C ₀₁, then according to identical operation, measure successively measuring point 2 ... the ultrasound wave longitudinal wave velocity of m, is designated as C ₀₂c _0m;

(6), when the suffered static load of concrete standard test specimen is respectively P ₁p _ntime, according to the operation of step (5), respectively each measuring point on concrete standard test specimen is carried out to ultrasound examination, and record the measuring point 1,2 of concrete standard test specimen under corresponding static load ... the ultrasound wave longitudinal wave velocity at m place, is designated as: C ₁₁, C ₁₂c _1m..., C _n1, C _n2c _nm, then obtain respectively corresponding static load P ₀, P ₁p _nthe mean value of the ultrasound wave longitudinal wave velocity of lower concrete standard test specimen, is designated as C ₀, C ₁c _n, wherein:

(7), by the mean value C of the ultrasound wave longitudinal wave velocity of concrete standard test specimen under the different static load effects that obtain ₀, C ₁c _nthe injuring relation formula of difference substitution concrete material in, wherein: k=0,1,2 ... n, obtains the impairment value D of corresponding concrete standard test specimen under different static loads ₀, D ₁d _n, then with the stress value of the concrete standard test specimen under different static load effects for horizontal ordinate, with the impairment value D of corresponding concrete standard test specimen under corresponding stress state ₀, D ₁d _nfor ordinate, with MATLAB mathematical software, carry out the data fitting of B batten, obtain the cubic B-spline smooth curve of stress-damage function, just obtains the damage Evolution of concrete material under static load effect.

2. concrete material as claimed in claim 1 damages the measuring method developing under static load effect, it is characterized in that in described step (2), measuring point is 3 and divides equally on the diagonal line that is distributed in plane.