CN105372171A - Concrete cracking overall process testing device based on true environment - Google Patents

Abstract

The invention provides a concrete cracking overall process testing device based on a true environment. The device comprises a base, wherein an environmental box, a concrete sample containing device, a true environment simulation system and a loading system are arranged on the base; the environmental box is isolated from the surroundings; the concrete sample containing device is arranged in the environmental box and comprises a fixed chuck, a movable chuck and a sample middle fixed side formwork, the fixed chuck, the movable chuck and the sample middle fixed side formwork are spliced to form a concrete sample containing space, the fixed chuck is fixedly arranged in the environmental box, and the movable chuck is movably arranged; the environmental box and the concrete sample containing space are provided with temperature sensors; the true environment simulation system at least comprises a temperature regulation device which is arranged in the environmental box and the concrete sample containing device to simulate the set true environment at temperature; the loading system enables the movable chuck to be fixed or move in the axis direction, and a displacement/deformation sensor is arranged on the movable chuck to sense deformation of a concrete sample; a stress sensor is arranged to sense the load borne by the sample. The device can be used for testing the whole process of development of temperature, stress and other factors of concrete in a changeable environment from the test angle.

Description

Based on the concrete cracking overall process test unit of true environment

Technical field

The invention belongs to Hydraulic and Hydro-Power Engineering technical field, relate to a kind of concrete cracking overall process test method based on true environment and adopt the test unit of the method, more specifically, relate to the device of the cracking whole process simulation test of mass concrete.

Background technology

For a long time, " not splitting without dam " is unsolved world-famous puzzle always, and the appearance in crack affects the outward appearance of dam structure, performance and safety, finally has influence on the people's lives and property.The generation how reducing even crackle preventing just becomes the problem that engineering construction person must consider.Along with association area is theoretical and the progress of technical research, the research work in dam concrete crack achieves obvious progress, and particularly Temperature Controlling of Mass Concrete anticracking work, has defined basic theory and the method system of comparatively perfect at present.But in view of the complicacy of Hydraulic and Hydro-Power Engineering, the particularly abominable of location environment, dam concrete crack problem does not still thoroughly solve.

Cause the factor in concrete generation crack a lot, structure, material and construction factor all likely become the inducement that crack occurs, but for dam, particularly at the dam that large temperature difference high altitude localities is built, around weather environment becomes the emphasis factors that temperature controlled anticracking controls gradually.Atmospheric environment not only surrounds whole concrete works in real time, and the changeable of atmospheric environment also produces important impact to engineering, the particularly temperature of surrounding environment, humidity, rainfall, the factor such as wind speed and solar radiation, drastically influence the generation of distress in concrete, the affecting laws that atmosphere environment impact factor produces distress in concrete how, its influence degree has again much, does not also come to a conclusion at present.Therefore, develop and just become needed for dam concrete engineering construction based on the concrete cracking overall process test unit of true environment and method.

Summary of the invention

The object of the invention is to improve the limitation in the simulation of existing concrete temperature stress and crack research and deficiency, there is provided a kind of from test angle, to the device that the development overall processes of factor under changeable environment condition such as concrete temperature and stress are tested.

Technical solution of the present invention is:

Concrete cracking overall process test unit based on true environment provided by the invention, comprises a base, is provided with on the base:

One environmental cabinet, at least has wall and upper cover, forms a closed space, separates with surrounding environment;

One concrete sample accommodating device, it is arranged in this environmental cabinet, it comprises fixed bolster plate in the middle part of fixed chuck, active chuck, test specimen, three's split forms a concrete sample accommodation space that upper end is uncovered or upper and lower side is all uncovered, described fixed chuck is fixedly installed in this environmental cabinet, and described active chuck can be arranged movably along the axis of the length direction of described concrete sample accommodation space;

At described environmental cabinet or described environmental cabinet and concrete sample accommodation space set temperature sensor;

One true environment simulation system, it at least comprises a temperature control equipment, and it is heating and/or cooling device, and it is arranged on described environmental cabinet and concrete sample accommodating device and at least proposes fixed true environment at temperature patrix to provide;

One loading system, comprise a framework, a gearing and propulsion system, described framework is arranged on described base, this gearing comprises a straight-line motion mechanism, driven member is wherein fixed by the sidewall entered environment case of described environmental cabinet and described active chuck and this active chuck position is fixed or moves at described axis direction, and the driving link in this straight-line motion mechanism is fixing on the frame; Described propulsion system are arranged on said frame, connect this driving link in described straight-line motion mechanism;

Described active chuck or the parts that are connected with active chuck arrange the distortion of displacement/deformation-sensor perception concrete sample; Described straight-line motion mechanism arranges the load that strain gauge perception test specimen bears.

With described test unit suitably, also comprise a computing machine, this computing machine is connected with a control system by data line, and this control system comprises: the control module controlling master trip machine true environment simulation system each topworks action; With the control module controlling concrete sample loading system medium power device action in master trip machine;

Described computing machine is also by the signal output part of the temperature sensor of monitoring of environmental parameter described in data line;

The signal output part of the displacement/deformation-sensor of the displacement/distortion of described monitoring concrete sample;

The signal output part of the strain gauge of described monitoring test specimen stress is connected;

The control signal output terminal of described control system is connected with the control end of each topworks.

Temperature control unit accepts the instruction of computing machine, and control topworks and heating/cooling device work, the temperature making concrete sample accommodation space also can comprise environmental cabinet meets the parameter of setting.

Displacement/deformation control unit controls the propulsion system in topworks and loading system together with Loading Control unit.

Data handling system in computing machine calculate concrete sample in the true environment of described simulation comprise restraint stress, free variable, elastic modulus, distortion are separated, creep at least one result exporting.

The shape of cross section of described accommodation space is: two ends are the shorter heads of width greater depth, and centre is the interlude that width smaller length is longer, and described head is connected transition with interlude by cone section; Splicing seams in the middle part of described fixed chuck and active chuck and test specimen between fixed bolster plate is positioned at the interlude scope of this accommodation space.

Further, the accommodating stationary installation of described test specimen can also comprise a cope match-plate pattern, and its described upper end closing described concrete sample accommodation space is uncovered.

Seam between described side template and described active chuck and/or fixed chuck leaves gap, this gap comprises the gap between the termination of side template and described active chuck, to ensure test specimen side template and active chuck non-contravention when compressing, also comprise the gap between the side of side template and fixed chuck and active chuck.

Described side template can be arranged in this environmental cabinet transverse shifting.

In use, concrete directly can be poured in described concrete sample accommodation space and form test specimen, also can be placed in described concrete sample accommodation space by what make with the test specimen of this test specimen accommodation space form fit.

Being arranged on heating in the described climate control system in described environmental cabinet and/or cooling device can be in the tank wall being arranged on described environmental cabinet or in the space closed, described tank wall has hollow chamber, and/or, arrange described fixed chuck, active chuck and side template in the accommodating stationary installation of test specimen at least one there is hollow chamber;

Each described hollow chamber arranges import and is communicated with the medium channel of described heating or cooling device with outlet, described topworks can be the discharge pump of the electrical heating coil arranged on the medium channel of this heating-cooling device or the media flow driving heating or cooling, in test providing heat energy or cold energy as required.

In the present invention, climate control system main in Reality simulation environmental system, can have two parts, and a part arranges on environment casing, and another part is arranged in the accommodating stationary installation of test specimen.Environmental cabinet is arranged, is more the temperature in Reality simulation environment, and arranges in the accommodating stationary installation of test specimen, the temperature of such as concrete dam in true environment can be simulated at short notice.So comprehensively climate control system is not all had in test unit of the prior art.

In the present invention, can directly concrete be cast directly in the concrete sample accommodation space of the accommodating stationary installation of test specimen, like this, just can test concrete from lean state to solidifying again to the sclerosis dilatational strain of complete procedure and the change of stress in the true environment of simulation, like this, for such as dam from building, be solidified to the stress of hardening process, strain can test under difficult environmental conditions, obtains comprehensive data, for the design of dam, construction provide valuable information.The test yet not accomplishing this complete procedure all do not expected by test unit of the prior art.Certainly, the accommodating stationary installation of test specimen in test unit provided by the invention also can be tested the concrete sample made.

Computer control system provided by the invention is essentially prior art, realize following function wherein: when pushing against described active chuck because test specimen is out of shape in the true environment simulated, strain gauge collects stress, be connected with propulsion system with the signal output part of data output system by data handling system and start propulsion system and drive active chuck to move until the stress drop that strain gauge senses is as low as zero, described propulsion system stop.

Such structure can make this test unit realize the tests such as free variable.

Be exactly after free variable in addition, start propulsion system and drive active chuck move and reduce deflection, obtain displacement by institute's displacement sensors, obtain corresponding stress value by described strain gauge.

Described true environment simulation system is except described weather adjustment device, the at least one regulating device arranged in described environmental cabinet can also be comprised: humidity control apparatus, solar radiation regulating device, rainfall regulating device, wind-speed adjusting device, correspondingly, also comprise as at least one in lower sensor: humidity sensor, solar radiation sensor, rainfall sensor and air velocity transducer, it is connected with described computing machine, the described topworks that described control system connects.

Particularly, can on the tank wall of described environmental cabinet apertured, connecting line, this pipeline connect supply gas, at least one sent in vapour, air-supply and water injector, correspondingly form humidity control apparatus, rainfall regulating device and wind-speed adjusting device; And/or apertured on the tank wall of described environmental cabinet, arranges the light fixture formation solar radiation regulating device that simulated solar irradiates in hole.

Each topworks associates with described control system the true environment making to simulate setting.

Regulating device described in each can also be establish one's own system, and such as temperature control equipment comprises heating controller, temperature controller, and it connects heating element and temperature sensor and realizes heating function.Like this, can the structure of simplified control system.

Further, described framework is the framework of the rectangle comprising two crossbeams and two column formations, a fixed cross beam is fixed on the described base of described fixed chuck side, two described columns described fixed cross beam that is connected abreast is positioned at described environmental cabinet both sides, a fine motion crossbeam is arranged on the described base of described active chuck side, be connected with described column, described propulsion system are arranged on this fine motion crossbeam, form reaction frame thus, described straight-line motion mechanism is connected with active chuck through this fine motion crossbeam, the support section of described displacement/deformation-sensor and described strain gauge is fixed on described base directly or indirectly.

Framework provided by the invention, two one, crossbeams are fixed on described base and form fixed cross beam, and another is just arranged on described base does not have fixed sturcture to form fine motion crossbeam with this base, and loading system is arranged on fine motion crossbeam.

Like this, when loading system exerts a force to test specimen, framework can bear very large stress and may have very little distortion, but this power and distortion can not pass to base.Therefore, the measuring accuracy of displacement transducer and force snesor, not by the impact of frame deformation, ensures good measuring accuracy.

The material of described column and sectional dimension are: ensure that its rigidity is the 5-20 power doubly of bearing the maximum strength stress of concrete and indeformable, or stiffness K is more than or equal to 2MN/mm; And/or its temperature deformation is less than 10 microns when ensureing that its temperature stability is in the temperature range (such as-20-80 DEG C) tested.

Described framework provided by the invention, adopts upright post cross-beam type, Stability Analysis of Structures, and column wherein has enough rigidity and temperature deformation stability in addition, can the precision of warranty test well.

Further, the described case lid of described environmental cabinet arranges form, makes process of the test visual.

The preferred servomotor of described propulsion system, connects worm reduction gear gear train.Such propulsion system make the large raising of control accuracy, feedback speed, efficiency.

The gear train of described rectilinear motion adopts screw-drive mechanism.

At described base, one hoisting gear is also set, a base plate is set in the accommodating stationary installation of described test specimen for placing test specimen or pouring into a mould test specimen thereon, this base plate connects this hoisting gear, by running this hoisting gear, test specimen can be moved into from concrete sample accommodation space or shift out.

An ancillary test machine can also be comprised in test unit provided by the invention, this ancillary test machine comprises a test specimen accommodating cavity for the identical test specimen of the test specimen placed with test in described master trip machine, in this test specimen accommodating cavity, described temperature control equipment is set, or at least one in described temperature control equipment and following regulating device is set: humidity control apparatus, solar radiation regulating device, rainfall regulating device and wind-speed adjusting device; Set temperature sensor in this test specimen accommodating cavity, also arrange as at least one in lower sensor: humidity sensor, solar radiation sensor, rainfall sensor and air velocity transducer, sensor described in each is connected with described computing machine, and this control system connects described regulating device and regulates the accommodating the cavity environment parameter of described test specimen identical with described master trip environmental cabinet; Displacement/deformation-sensor is also set in this test specimen accommodating cavity with the distortion of perception test specimen.

Described control system also comprises the control module controlling true environment simulation system various described topworks action in described ancillary test machine.

Test specimen accommodating cavity put into by the test specimen the same with master trip device, makes test specimen can Free Transform.Test specimen in ancillary test machine in same environment, for contrasting with the test specimen in master trip device.Ancillary test machine is under test specimen and the enough little condition of machine bed plate friction factor, measures the Free Transform with auxiliary test specimen under the synthermal condition of master trip machine.Synthermal condition parallel experiment machine, makes test figure possess integrality.

Test unit provided by the invention, is mainly used in distress in concrete mechanism and temperature stress test.Under multiple temperature control measures condition can be carried out, concrete from the test of evolution being poured into himself temperature stress sclerosis overall process, the process that this process can comprise adiabatic temperature rise, thermal expansivity, elastic modulus and the parameter such as to creep develops in time; The all right true weather environment of analog simulation, emulates the temperature stress under natural cause impact and Cracking Mechanism.This test unit can arrange different temperature and constraint degree condition as required, comprises the process etc. of thermal insulation, constant temperature, setting temperature rise temperature drop.Tested by concrete cracking whole process simulation, evaluate concrete cracking resistance.

Use above-mentioned test unit, based on the concrete cracking overall process test method of true environment, comprise the following steps:

(1), by pouring concrete in described concrete sample accommodation space, or concrete sample to be arranged in this concrete sample accommodation space in stationary installation; The two ends of described test specimen are connected with described fixed chuck and active chuck respectively;

(2) a true environment simulation system is built, the at least temperature parameter in described environmental cabinet and/or concrete sample accommodating device is made to reach the true environment requirement setting and will simulate by described topworks, environment in this environmental cabinet can be a constant environment, or at the environment that setting range intrinsic parameter changes;

(3) then under the true environment of setting, at least one following test procedure is carried out:

A. freely retrain:

Concrete sample one end is fixed by test unit, other end retractable, provide the true environment of setting in true environment simulation system under, free variable test is carried out to this test specimen, in the time zone (t) of setting, the setting period gathers deflection ε (t)

When expanding or shrinking appears in test specimen, namely the strain gauge arranged demonstrates stress value, namely propulsion system are started, straight-line motion mechanism is moved in the direction that deformation direction is identical until strain gauge display stress value is zero, obtains the numerical value of free variable now from displacement/deformation-sensor.

The concrete operations freely retrained are: the two ends of concrete sample clamp by test unit, one end is fixed, one end can control mobile, under true environment simulated conditions, described test specimen can not added load by control end, setting-up time interval (t), according to the data that displacement/deformation-sensor and strain gauge detect, propulsion system action is made by control system, thus, the free displacement making described test specimen is μ (t), is concrete free variable ε (t) of t.

Measuring concrete free variable object is for the various distortion of concrete is separated.

B. restraint stress:

The two ends of concrete sample clamp by test unit, one end is fixed, one end can control mobile, namely one end free-extension be connected with active chuck of test specimen is first allowed, after test specimen has an elongation or amount of contraction in described true environment, setting-up time interval (t), according to the data that displacement/deformation-sensor and strain gauge detect, propulsion system action is made by control system, thus, the displacement of test specimen movable terminal is reduced, tests the concrete stress in different degree of restraint situation, restraint stress test is carried out to this test specimen.

Concrete operations are: the two ends of concrete sample clamp by test unit, and one end is fixed, and one end can control mobile.Under true environment simulated conditions, the free displacement of described concrete sample movable terminal is μ (t), according to actual needs, by computer control system, displacement/Deformation control system and loading system, the displacement of test specimen movable terminal is reduced, at this moment described strain gauge record different degree of restraint of each moment be constraint factor f (t) situation under concrete temperature stress σ (t).

The displacement that movable terminal reduces is:

f(t)×μ(t)(6)

In formula, t is the time, and f (t) is concrete constraint factor during t, and μ (t) is the free displacement of concrete sample movable terminal.

C. elastic modulus:

Concrete elastic modulus measured by concrete cracking overall process test unit based on true environment, and set interval △ t in the computing machine of computing machine, namely every △ t time measurement once concrete elastic modulus.

Particularly, set interval △ t in a computer, every the △ t time interval, according to the data that displacement/deformation-sensor and strain gauge detect, propulsion system action is made by control system, thus, test specimen movable terminal is made to do a change in displacement, namely for the change in displacement value (such as 2 microns) of setting, when piece lengths extends or shortening length reaches setting change in displacement value (such as 2 microns), a change in displacement is done to test specimen movable terminal, this setting change in displacement value is pushed back or pulled back, the STRESS VARIATION that this change in displacement causes is measured according to strain gauge, elasticity modulus test is carried out to this test specimen.

Concrete operations are: every the △ t time, according to the data that displacement/deformation-sensor and strain gauge detect, propulsion system action is made by control system, thus, test specimen movable terminal is made to do change in displacement Δ μ (t), it refers to the difference of the length in a moment and this moment on test specimen, draw distortion Δ ε (t), it refers to that the difference of the length in a moment and this moment on test specimen is divided by test specimen total length, be Δ σ (t) according to the STRESS VARIATION amount that strain gauge is measured, then the modulus of elasticity of concrete of t is:

$E\left(t\right)=\frac{\mathrm{\Δ}\mathrm{\σ}\left(t\right)}{\mathrm{\Δ}\mathrm{\ϵ}\left(t\right)}---\left(7\right)$

According to the time interval of design, computer control system automatically can measure not modulus of elasticity of concrete in the same time, can obtain the elastic modulus of concrete in whole evolution.

The separation of being D. out of shape

According to the temperature variation that thermal expansion coefficient of concrete and temperature sensor record, draw concrete temperature deformation, in conjunction with the Free Transform recorded, to the test of the separation that this test specimen is out of shape.

The separation of distortion refers to and is separated recording total deformation.Because recording total deformation is that various deformation mixes, the distortion (as expanding with heat and contract with cold) having temperature to cause, has the distortion that drying shrinkage causes, has autogenous volumetric deformation, has stressed distortion caused etc.Here separation, such as separates, that part of distortion that only temperature causes to understand concrete deformation only under temperature action etc. from recording distortion the inside.

Concrete operations are: first do free constraint: concrete sample one end is fixed by test unit, other end retractable, the true environment of setting is provided by true environment simulation system, free variable test is carried out to this test specimen, in the time zone (t) of setting, the setting period gathers deflection ε (t).

After the 1 day length of time of concrete, its thermal expansivity would not change substantially again, and be commonly considered as a constant, this parameter also can be recorded by special hot expansion coefficient tester, thinks constant α here.According to temperature variation Δ T (t) that thermal expansion coefficient of concrete α and temperature control system record, concrete temperature deformation under true environment simulated conditions can be drawn:

Δε _T(t)＝α·ΔT(t)(8)

In conjunction with Free Transform ε (t) recorded, be separated, other distortion Δs ε can be drawn _at (), mainly comprises autogenous volumetric deformation and dry-shrinkage deformed:

Δε _a(t)＝ε(t)-Δε _T(t)(9)

E. concrete creep

The Free Transform that the modulus of elasticity of concrete recorded according to abovementioned steps C and abovementioned steps A record, can calculate not by concrete stress during Creep Effect; According to the data that displacement/deformation-sensor and strain gauge detect, make propulsion system action by control system, thus what make test specimen is deformed into zero, at this moment records another stress, according to these two STRESS VARIATION, this test specimen is carried out to the test of concrete creep.

Concrete operations are: according to modulus of elasticity of concrete E (t) drawn and Free Transform ε (t), can to calculate under true environment simulated conditions by concrete stress σ (t) during Creep Effect:

σ(t)＝ε(t)·E(t)(10)

According to the data that displacement/deformation-sensor and strain gauge detect, make propulsion system action by control system, thus control concrete deformation, make it be deformed into zero, at this moment recording stress is σ ₀(t), then the stress caused of creeping under true environment simulated conditions is reduced to:

σ _c(t)＝σ(t)-σ ₀(t)(11)

Pass through σ _ct the size of () can draw the influence degree of concrete creep, wherein t is the time.

F. concrete cracking overall process

Allow concrete sample in the temperature variation of setting, bear tension or in the Reality simulation environment of setting, apply pulling force until cracking, obtain concrete cracking temperature variations or in the true environment of setting the tensile strength of concrete sample or limit stretch value.

The concrete operations of concrete cracking overall process can be: concrete temperature changes to design temperature from initial temperature, test specimen two ends are fixed, one end applies pulling force, when tension data reduce suddenly, displacement increases suddenly, corresponding time m-stress, time m-distortion/displacement curve on there is sudden change time, concrete cracking, obtain at this moment concrete correlation parameter, comprise temperature, tensile strength, limit stretch value.

G. concrete cracking overall process evaluation is carried out to this test specimen

The test figure of integrating step A, B, C, D, E, F and test condition and result, carry out assessment of performance to concrete sample in the Reality simulation environment of test setting.

Further, in conjunction with the test figure one of at least of A, B, C, D, E, F above and result, namely in conjunction with concrete relevant environmental parameter as temperature, stress, displacement and distortion, to this test specimen carry out from concrete sample intact or from building until cracking overall process make evaluation.

In this step, can for weather environment change this feature complicated in engineering reality, arrange multiple environmental factor variation model, described environmental factor parameter comprises environment temperature, comprises at least one in humidity, rainfall, wind speed and solar radiation in addition.

Concrete correlation parameter temperature, stress, displacement and distortion can as the cracking indexs under real-world temperature condition, for engineering design, construction and construction provide important test reference.

From the above, described test unit and method can be tested Free Transform concrete under real environmental conditions; Can test the temperature stress of the different restrained condition of concrete under real environmental conditions; Can test elastic modulus evolution concrete under real environmental conditions; Separation test can be carried out to various deformation concrete under real environmental conditions; Can test concrete creeping under real environmental conditions; Can according to test under real environmental conditions draw concrete temperature, stress, the isoparametric evolution of strain and dehiscence process, assay is carried out to concrete cracking overall process, for concrete Crack Control Design provides reference.

The simulation of described true environment, refers to according to the on-site hydrometeorological condition of Practical Project, the relevant informations such as input environment temperature, humidity, rainfall, wind speed and solar radiation, engineering weather environment that is virtually reality like reality.In this step, for weather environment change this feature complicated in engineering reality, multiple environmental factor variation model can be set.

Method provided by the invention, can also until each stage of such overall process that ftractures or various aspects carry out testing and evaluating from pouring concrete test specimen.

In the above-mentioned methods, for the simulation of true environment, can adopt with the following method:

1. environment temperature

For locality situation and determine, i.e. the locality of Reality simulation environment, above monthly mean temperature data is fitted to a cosine curve, following formula (1) is the computing formula after matching:

Consider climate simulation, adopt following formula to calculate:

$T_a=T_{am}+A_a\cos \[\frac{\mathrm{\π}}{6}\left(\mathrm{\τ}-{\mathrm{\τ}}_0\right)\]---\left(1\right)$

In formula, T _afor temperature, T _amfor average temperature of the whole year, A _afor temperature year luffing, τ is time (moon), τ ₀for the time (moon) of maximum temperature.

Consider temperature diurnal variation, adopt following formula to calculate:

$T_a^d=T_a+Acos\[\frac{\mathrm{\π}}{12}(t-14)\]---\left(2\right)$

In formula, for daily temperature, T _afor monthly mean temperature, A is temperature diurnal variation amplitude, t be moment in 1 day (time) determine according to the Various Seasonal of different regions.

2. solar radiant heat

Concrete structure is often exposed under solar radiation, and it has material impact to concrete temperature.The heat that in unit interval inherent unit area, solar radiation comes is S, and wherein set the part that absorbed by concrete as R, remainder is reflected, then:

R＝α _s·S(3)

In formula, α _sfor absorption coefficient, also referred to as coefficient of blackness, concrete surface generally gets 0.65.

S＝S ₀(1-kn)(4)

In formula, S ₀for fine day solar radiant heat, n is cloud amount, and k is coefficient, and these three numerical value can be provided by local weather station.

The temperature that the impact at sunshine is equivalent to surrounding air increases Δ T _a,

ΔT _a＝R/β(5)

In formula, β is concrete surface coefficient of heat emission, can calculate according to surface roughness and wind speed.

3. rainfall

The rainfall amount of inquiry engineering location meteorological department, carrys out simulated rainfall by rainfall equipment and rainfall amount controller.

4. wind speed

The wind speed of the inquiry on-site meteorological department of engineering, threshold wind velocity analogue means, and concrete surface coefficient of heat transfer can be drawn according to wind speed.

Under concrete cracking overall process test unit based on true environment provided by the invention can carry out multiple temperature control measures condition, concrete is from the evolution being poured into himself temperature stress sclerosis overall process, the process that the parameter such as comprise adiabatic temperature rise, thermal expansivity, elastic modulus and creep develops in time, the all right true weather environment of analog simulation, emulates the temperature stress under natural cause impact and Cracking Mechanism.This device can arrange different temperature and constraint degree condition as required, comprises thermal insulation, constant temperature, setting temperature rise temperature drop process etc.Tested by concrete cracking whole process simulation, evaluate concrete cracking resistance.

These apparatus and method tool has the following advantages:

1) this test unit adopts environmental cabinet and concrete sample accommodation space dual structure, can test from test specimen is built, in addition various true environment can be simulated, can fully understand that pouring concrete arrives the situation of sclerosis complete procedure, for industry-by-industry xoncrete structure provides comprehensive test figure.

2) have employed the reaction frame structure of high rigidity, be suitable for the permanent creep test of concrete.

3) have employed floating frame structure, i.e. two end floor beams, one is fixed on base, and one is only positioned on base, and measuring accuracy is higher, and systematic error is less.

4) add test specimen automatic lifting device, after making specimen molding and test, test specimen processing procedure saves muscle power, convenient operation;

5) add the function of test specimen in process of the test adjustment constraint, adjust this micro-adjusting mechanism in process of the test and test specimen constraint can be made to be gradually reduced to zero;

6) real-time follow-up record data, sampling time interval can freely be arranged;

Therefore, this device is the testing equipment being widely used in the desirable high performance-price ratio of the industries such as mine, mining industry, underground works, metallurgical construction, national defence people's air defense, universities and colleges, communications and transportation.

Below by drawings and Examples, the present invention is described in further detail.

Accompanying drawing explanation

Fig. 1 is the structural representation of test unit provided by the invention.

Fig. 2 is the structural representation of the external structure of master trip machine in test unit provided by the invention.

Fig. 3 is the structural representation of the inner structure of master trip machine provided by the invention.

Fig. 4 is the A portion partial enlargement structural representation of Fig. 3.

Plan structure schematic diagram after the case lid 22 that Fig. 5 is the removal environmental cabinet of the machine of master trip shown in Fig. 3 and cope match-plate pattern 314.

Fig. 6 is the A portion partial enlargement structural representation of Fig. 5.

Fig. 7 is that displacement transducer arranges structural representation.

Fig. 8 is side template medium recycle circuit structural representation.

Fig. 9 is dielectric heating schematic flow sheet.

Figure 10 is the structural representation of an embodiment of heating arrangement.

Figure 11 is the control principle drawing of the concrete cracking overall process test that the present invention is based on true environment.

Figure 12 is another kind of control principle drawing.

Figure 13 is functional schematic of the present invention.

Figure 14 is temperature based on true environment and concrete stress graph.

Embodiment

Concrete cracking overall process test unit based on true environment provided by the invention as shown in Figure 1, comprises an a master trip machine A and ancillary test machine B.Also be provided with computing machine D, computing machine D is connected with a control system D1 by data line L, and this control system D1 comprises:

1. in master trip machine A and ancillary test machine B, control the control module of the various topworks of true environment simulation system;

2. in master trip machine A, control the control module of the propulsion system in the control module of topworks that concrete sample loads and loading system.

The data line L of computing machine D also connects:

1. the signal output part of the temperature sensor of monitoring of environmental parameter in master trip machine A and ancillary test machine B;

2. in master trip machine A and ancillary test machine B, monitor the signal output part of the displacement/deformation-sensor of the displacement/distortion of concrete sample;

3. in master trip machine A, monitor the signal output part of the strain gauge of test specimen stress.

The major function of computing machine D is:

1. the parameters of true environment and the Changing Pattern of parameters that will simulate are set by computing machine D, the action of each performance element of control simulation true environment accordingly, also will accept the environmental parameter of each sensor feedback of monitoring of environmental parameter and control the operation of topworks accordingly by control module;

2. the various test parameterss in test are set by computing machine D, such as: the monitoring time interval of displacement/deformation-sensor and strain gauge;

3. the incidence relation of propulsion system action described in control module instruction and described displacement/deformation-sensor and described strain gauge is set;

4. export various test findings in each test by the data handling system in computing machine D and data output system.

One computer control system, comprises the collection be made up of aforementioned each sensor and has temperature, the data acquisition system (DAS) of displacement/distortion and stress and data processing and output system at least; The signal output part of sensor described in each is connected with the corresponding signal input end of the data handling system of computer control system and data output system, described data handling system is connected with the signal input part of a topworks with the signal output part of data output system, this topworks comprises the propulsion system in loading system and the heating in weather adjustment device and/or cooling device, with adjusting ambient case and/or the environment of concrete sample accommodation space and the true environment of setting consistent and/or start or stop described propulsion system; Described data handling system connect with data output system and calculate concrete sample in the true environment of described simulation comprise restraint stress, free variable, elastic modulus, distortion are separated, creep at least one result exporting.

On test specimen with in the environment residing for test specimen, a true environment set is simulated by computing machine D and control system D1 and the topworks of the Reality simulation environment arranged in master trip machine A and ancillary test machine B, in this context, the distortion of test specimen in the environment such as different temperatures is obtained by displacement/deformation-sensor by computing machine D and control system D1, the loading system arranged by computing machine D and control system D1 again and control applies pulling force or pressure to test specimen in master trip machine A, complete and such as freely retrain, restraint stress, elastic modulus, the separation of distortion, the test of concrete creep and concrete cracking overall process, draw concrete various performance parameter in various simulated environment, identical test block in ancillary test machine B is in freely unconfined state, the distortion of this test block etc. can be as a comparison.

Just test unit provided by the invention and test method are described in detail below.

Fig. 2 illustrates a kind of master trip machine, and it comprises base 1, and base 1 arranges environmental cabinet 2, and base 1 is also provided with a framework 4, is also provided with the accommodating stationary installation 3 (see Fig. 3, Fig. 5) of test specimen in environmental cabinet 2.

As shown in Figure 3, environmental cabinet 2 comprises the uncovered casing in upper end 21 and closes the uncovered case lid 22 in described upper end, an enclosure space separated with surrounding environment is formed, to be built up the true environment of the setting that test needs wherein by true environment simulation system with this.

The isolated inner heat of environmental cabinet 2 transmits to reaction frame and framework 4 and base 1, and also isolated outside heat internally transmits simultaneously, ensure that temperature controlled easy control, avoids the impact of rising-heat contracting-cold on measurement result of plant bottom case 1 simultaneously.

As shown in Figure 3 and Figure 5, the accommodating stationary installation 3 of described test specimen, be arranged in this environmental cabinet 2, comprise fixed bolster plate 313 in the middle part of fixed chuck 311, active chuck 312, test specimen, three's split forms a concrete sample accommodation space 31 that upper end is uncovered or upper and lower side is all uncovered, the shape of cross section of this accommodation space 31 is: two ends are the shorter heads of width greater depth, and centre is the interlude that width smaller length is longer, and described head is connected transition with interlude by cone section; Splicing seams in the middle part of described fixed chuck 311 and active chuck 312 and test specimen between fixed bolster plate 313 is positioned at the interlude scope of this accommodation space 31, side and the active chuck 312 of side template 313 leave sideshake a1, leave end clearance a2 (as shown in Figure 6) between the end face of side template 31 and active chuck 312.The shape of concrete sample accommodation space 31 is substantially equal to be the shape of test specimen C.

The structure of the accommodating stationary installation 3 of a kind of test specimen is: fixed chuck 311 is fixedly installed on base 1, and active chuck 312 can be arranged on base 1 relative to base 1 along the axis of the length direction of described concrete sample accommodation space movably; The accommodating stationary installation 3 of test specimen also comprises a cope match-plate pattern 314, and its described upper end closing described concrete sample accommodation space 31 is uncovered.For the example of the accommodating stationary installation of the test specimen that upper and lower side is all uncovered, in this accommodation space 31, bottom surface establishes a base plate and lower bolster (not shown).304 Stainless Molding Boards totally 4 pieces of bolster and two side templates to be thickness be 70mm.

In use, concrete directly can be poured on the base plate in described concrete sample accommodation space 31 and form test specimen C, also can by being placed on the base plate of accommodation space 31 with the test specimen C of this test specimen accommodation space form fit of making.Supporting seat 31-1 (see Fig. 5) is set below base plate.

As shown in Figure 5 and Figure 6, in order to ensure the repetitive positioning accuracy of side template 313, it is installed fixed form and adopts T-slot guidance mode, side form slide block 313-1 is set firmly at side template 313 lateral surface, in environmental cabinet 2, relevant position sets firmly T-slot fixed block 313-2, side form slide block 313-1 is fixed in the T-slot on T-slot fixed block 313-2 slidably, make side template 313 can being displaced sideways at the longitudinal axis perpendicular to accommodation space 31, environmental cabinet sidewall is installed a screw rod 313-3, screw rod 313-3 is screwed onto on side form slide block 313-1, screw rod 313-3 sets firmly a control hand wheel 313-4.Rotate control hand wheel 313-4, drive side template 313 to horizontally slip in environmental cabinet 2 along T-slot by side form slide block.

As shown in Figure 6, the maximal regulated distance a1 between side template 313 side and active chuck 312 is 10mm, side template 313 can be transferred to laterally apart from maximum during the demoulding.Gap a2 between side template 313 end and active chuck is 5mm, ensures test specimen side template 313 and active chuck 312 non-contravention when compressing.Cope match-plate pattern 314 and lower bolster i.e. gapless between base plate and side template 313, ensure that test specimen C cement when making is not extruded, the gap a2 of side template 313 end and active chuck when making test specimen C with one section of very thin copper sheet pad firmly.

As shown in Figure 3, also comprise a stripper apparatus, the bottom surface of this base plate connects a jacking gear, this jacking gear connects and one ejects reducing motor 32, can be ejected reducing motor 32 and base plate is ejected accommodation space 31 and takes out concrete sample C easily by this.

Particularly, the demoulding adopts screw mandrel ejecting structure, is arranged on the two ends bottom test specimen, sprocket wheel chain is driven to be transferred to feed screw nut by ejecting reducing motor 32, the lifting of nut rotary screw drives push rod lifting, for being ejected by test specimen C, maximumly ejects distance 150mm.Push rod and end template and base plate place are provided with dust seal, prevent dust and foreign material from dropping in gap.The push rod via hole at base plate or lower bolster place adopts stainless-steel tube and bed die Type of Welding, ensures that liquid can not seepage.Need rotary side template control hand wheel 313-4 that side template 313 is removed some gaps before test specimen ejects.

The shape of test specimen accommodation space 31 makes test specimen be bone-shaped in collet segment shape, has Rouno Cormer Pregrinding Wheel transition, ensures that test specimen ruptures in effective length.

Be arranged on the framework 4 on described base 1, as shown in Fig. 2, Fig. 3, Fig. 4 and Fig. 5, framework 4 comprises two root post 41, fixed cross beam 42 and fine motion crossbeams 43, form a rectangle frame, the longitudinal direction of column 41 and accommodation space, namely the axis direction of concrete sample is parallel, and two crossbeams are separately fixed at the two ends of two columns.Fixed cross beam 42 is fixed on base 1, and fine motion crossbeam is arranged on base, but and does not have fixed sturcture between base.

The material of column 41 and sectional dimension are: ensure that its rigidity is the 5-20 power doubly of bearing the maximum strength stress of concrete and indeformable, or stiffness K is more than or equal to 2MN/mm; Further, the material of column and sectional dimension also ensure that its temperature stability is for its temperature deformation when-20-80 DEG C is less than 10 microns in temperature.

One straight-line motion mechanism is arranged on this fine motion crossbeam 43, concrete, as shown in Figure 4 and Figure 5, straight-line motion mechanism is the screw mechanism 44 that a ball screw nut component is formed, nut 441 in screw mechanism is fixed on constraint axle 443 by nut sleeve 442 through the crossbeam 43 that floats, constraint axle 443 is connected on the end face of active chuck 312 through the sidewall of environmental cabinet 2, makes this active chuck 312 position fix or move at described axis direction; The screw rod 444 be spirally connected with nut 441 is rotatably mounted on fine motion crossbeam 43.

Between constraint axle 443 and environmental cabinet 2, displacement/deformation-sensor 443-3 is set, particularly, constraint axle 443 is arranged and measures top board 443-1, environmental cabinet 2 lateral wall arranges supporting seat 443-2, this supporting seat 443-2 arranges displacement/deformation-sensor 443-3, and the sensing part of this displacement/deformation-sensor 443-3 is against to be measured on top board 443-1.Nut 441 connects strain gauge 441-1, and the sensing part on it is against on supporting seat or constraint axle 443 and senses stress.

This setup of displacement/deformation-sensor 443-3 it can be made to be subject to impact that propulsion system load test specimen and reduce accuracy of detection.This is because the fine motion crossbeam 43 in framework 4 is not connected with base 1, the counter-force of propulsion system tension and compression test specimen can not pass on base 1, and displacement/deformation-sensor 443-3 is fixed on environmental cabinet and equals to be fixed on base 1, so can not be affected.

As shown in figs. 4 and 7, displacement/deformation-sensor 443-3 is arranged on the two ends of test specimen, is arranged symmetrically, respectively in 2 precision ± 1 μm, tunnel, as the same in same ancillary test B machine./ deformation-sensor scope is moved in master trip seat in the plane: ± 100 μm, and/deformation-sensor scope is moved in ancillary test seat in the plane: ± 2000 μm.

Supporting seat 443-2 is arranged on base 1, and when laboratory ambient temperature is constant, the relative position of displacement/deformation-sensor measuring junction and test specimen stiff end can not change, error free in theory.

Specific to a specific embodiment, described constraint axle 443, active chuck 312 and fixed chuck 311 all adopt the invar steel of high rigidity, and this material linear expansion coefficient is minimum is only (-20-100 DEG C) 1.4x10 ^-6/ DEG C, be only 0.000924mm/ DEG C to the impact of whole device, can deduct this error in experimental result, result is more accurate; Active chuck 312 adopts high precision railroad below and between base 1, has ensured measuring accuracy.

One loading system, comprises propulsion system, and these propulsion system are arranged on described framework 4, concrete, and propulsion system are as shown in Figure 4, Figure 5, are arranged on fine motion crossbeam 43.The servomotor 446 that the reductor 445 that propulsion system comprise spiral gear-worm and gear, reduction gear ratio reaches 650 is connected with reductor, these propulsion system are controlled by the Loading Control unit that computer calculate machine connects, and make it start and stop and limiting it turning to.And Loading Control unit is the signal sent according to set displacement/deformation-sensor and strain gauge, the requirement according to concrete test controls the startup of servomotor 446 and stops isoparametric.

The pitch of the screw rod 444 be spirally connected with nut 441 is 12mm.Straight-line motion mechanism so, individual pulse displacement is only 0.007 μm, and servomotor band close-loop feedback, substantially increases and add unloading precision, also can easily tackle even if threshold value is arranged on 1 μm.

The preferred servomotor of described propulsion system, connects worm reduction gear gear train.Such propulsion system make the large raising of control accuracy, feedback speed, efficiency.

Because do long term creep strain test (loading force is constant) with this test unit, adopt full servomotor Hardened gear face worm reduction gear type of drive, the accuracy controlled than stepper motor loading stress improves greatly.In experimentation, concrete deformation is very little, and servomotor 446 and reductor 445 match and use, and servomotor 446 speed is stepless adjustable, and loading step-length can select arbitrarily, therefore Bit andits control accuracy is higher than stepper motor; Kind of drive ball-screw, higher than common leading screw precision, transmission efficiency is much higher (95%) also, and transmission adopts rolling friction, long service life.

Described framework 4 adopts 45 steel makings, is designed to the syndeton of the fine motion crossbeam floated in fixed cross beam one end, one end, and when stressed, its distortion can not produce interference to displacement measurement, can not introduce measuring error.

Because of reaction frame and described framework floating end and fine motion cross beam movement during loading, and stiff end and fixed cross beam and test specimen fixed reference end motionless, displacement/deformation-sensor measure top board and test specimen stiff end relative position motionless, so can not measuring error be introduced.

Framed structure adopts upright post cross-beam type, and weight about 4 tons, can adapt to the rigidity requirement of long term creep strain testing requirements testing machine itself, (stiffness K >=2MN/mm).

Particularly, when loading frame bears 200KN load, maximum stress point is about 60MPa, is far smaller than material yield strength and tensile strength.When loading frame bears 200KN load, in framework, fixed cross beam and fine motion crossbeam bend laterally, two heel posts elongate and curve inwardly due to the effect of moment of flexure, axial total deformation is 0.04655+0.04670=0.09325mm, and rigidity is 200000/0.09325=2144772N/mm=2.14MN/mm.When loading frame bears 200KN load, framework minimum safety factor is 6.49.

Described framework provided by the invention, adopts upright post cross-beam type, Stability Analysis of Structures, and column wherein has enough rigidity and temperature deformation stability in addition, can the precision of warranty test well.

The constraint axle 443 at fixed chuck 311, active chuck 312 and two ends all adopts invar steel 4J36 to manufacture, the diameter 150mm of constraint axle 443, the elastic modulus of invar steel is large, linear expansion coefficient is very little, average linear expansion coefficient within the scope of 20-100 DEG C only has 1.4x10^-6/ DEG C, to measurement influential part length be 660mm, therefore be 0.000924mm/ DEG C to the Influence on test result of experiment, and it is substantially constant-80-100 DEG C time, can calculate or measure experimental result impact, measurement result is more accurate.

The described case lid of described environmental cabinet arranges form, makes process of the test visual.

Figure 11 gives the control principle drawing that the concrete cracking overall process based on true environment in an embodiment in test unit provided by the invention is tested.

As shown in figure 11, test unit provided by the invention also comprises a computing machine D and control system D1, and control system D1 comprises: the control module controlling the action of true environment simulation system various topworkies in master trip machine A and ancillary test machine B; And, control the control module of the propulsion system in the control module of topworks's action that concrete sample loads and loading system in master trip machine A.

Described computing machine D is connected with control system D1 by data line L, meanwhile, computing machine D is also connected by data line L and the signal output part of the temperature sensor of monitoring of environmental parameter, the signal output part of monitoring the displacement/deformation-sensor of concrete sample displacement/distortion, the signal output part of strain gauge of monitoring test specimen stress;

The control signal output terminal of described control system D1 is connected with the control end of each topworks.

The control module of described each topworks comprises: temperature control unit, displacement/deformation control unit and Loading Control unit, computing machine D provides instruction, namely control system D1 controls the action of each topworks: heating or cooling, load maintainer action is with direction initialization load or unload, allow test specimen C Free Transform or be controllably out of shape, and initial, the direction of action of topworks's action and stopping are controlled by computing machine D accepts the signal of displacement/deformation-sensor and the instruction sent Loading Control System.Data handling system in computing machine D carries out data processing for the information obtained from each sensor according to concrete test, calculates test structure and/or draw out parametric line to export.

Heating in the environmental cabinet 2 having temperature control unit to control and in the accommodating stationary installation 3 of test specimen or cooling device can be, cavity is set in the composition fixed chuck 311 of accommodating stationary installation, active chuck 312 and side template 313 inside, in cavity, passes into heating medium or heat eliminating medium by this cavity and extraneous connecting line.For a side template 313, as shown in Figure 8, in the internal cavities of side template 313, arrange water conservancy diversion grid, form tortuous flow path, internal diversion grid plays reinforcement effect simultaneously, indeformable after ensureing to add unloading test for a long time.And for example cope match-plate pattern 314 is also such structure, and as shown in Figure 3, this cavity at one end arranges medium inlet 313-5, arranges media outlet 313-6 at the other end.Medium inlet and outlet connecting media heat or cooling device, as shown in Figure 9 and Figure 10.Adapter 313-5 on the medium inlet of side template 313 connects the outlet of a pump 313-7, the inlet connection of pump 313-7 connects the outlet of a constant temperature oven 313-8, wherein refrigerator pipes 313-9 is set, connect refrigerating plant, compressor refrigerant in refrigerating plant adopts R502 nontoxic, environmentally safe.In constant temperature oven 313-8, heated cooling medium is established to adopt 40% glycol water, freezing point temperature-25 DEG C.The medium outlet of the entrance connection side template 313 of constant temperature oven 313-8.The inlet tube of pump 313-7 arranges heater coil 313-10.

Heating/cooling device as shown in Figure 9, needs to side template, cope match-plate pattern to such an extent as to carry heating medium or heat eliminating medium in the cavity at the places such as tank wall in fixed chuck, active chuck and even environmental cabinet 2 according to test.Pump 313-7 in this heating or cooling device, the refrigerating plant connecting refrigerator pipes 313-9 and heater coil 313-10 are topworks, and it is controlled by the temperature parameter set in computing machine D.In order to simplify the structure of computing machine, also temperature control unit can be separated whole or in part from computing machine D, its process flow diagram just can become Figure 12 from Figure 11.

The heating system of heater coil 313-10 as shown in Figure 10, jointing temp sensor a on inlet tube 313-12 on heating tube i.e. pump 313-7, the signal output part of this temperature sensor a connects the signal input output end of temperature controller b, the corresponding signal IO of the temperature data transmission end connection heating controller c of this temperature controller b holds, according to the temperature data that temperature controller b transmits, heating controller c exports the voltage, the electric current that are applicable to heater coil 313-10, heater coil 313-10 is generated heat, external embodiment design temperature, provides the simulation of the true environment of setting.

If provide low temperature, heater stop works, cooling device starts, circulating refrigerant in refrigerator pipes 313-9, medium d glycol water in cooling constant temperature oven, pump 313-7 works, in the cavity of fixed chuck, active chuck and side template, carry heat eliminating medium, carries in the heat interchanger that also can simultaneously arrange in environmental cabinet.Pump 313-7 is as topworks, and it starts and stops and rotating speed is subject to the control of temperature control unit, provides required temperature.

In order to measure the temperature of test specimen, can temperature sensor be plugged in test specimen, the general axial line place temperature sensor of monitoring test specimen being plugged in test specimen.For this reason, side template 313 and fixed chuck and live splint each template first-class all can there is template thermometer hole 1, in embodiment as shown in Figure 1, side template is established a thermometer hole 313-11.Cope match-plate pattern 314-1 is separately furnished with three test specimen thermometer hole 314-2, and inner or surperficial for temperature sensor being inserted to test specimen C, temperature sensor is distributed in piece lengths 1/4,1/2 and 3/4 place.

Cope match-plate pattern is provided with cope match-plate pattern handle 314-2.

Cope match-plate pattern placing flat, above test specimen, can freely remove and install, and circulation fluid junction medium inlet 313-5 and media outlet 313-6 adopt flexible pipe to be connected, and need not dismantle flexible pipe when removing and installing, and ensures the reliable no leakage of sealing.

For ensureing that temperature transmission is even, the lattice structure of template inside, confined liquid is at the nowed forming of inside, and four pieces of hollow template inside up and down of test specimen are same journey circulation fluid; PID accurate Calculation controls heating and refrigerating plant, ensures meticulous cold and hot compensation, the flow of control inputs template circulation fluid, makes the temperature of circulation fluid meet the various requirement of test.

The temperature of environmental cabinet is made to meet the various requirement of test.Environmental cabinet housing adopts stainless steel, inner fill insulant material, and seal tight without distortion, thickness is 150mm.

Test specimen, template, chuck and partially restrained axle are wrapped in inside by thermal environment case.

Except containing refrigeration unit, heating arrangement, can also comprise air humidifying device and humidifier, rainer and spray equipment, air flow system and fan assembly, its schematic diagram as shown in figure 12.

True environment simulation system also comprises solar radiation device and bulb.

Simulated atmosphere physical environment, above-mentioned each device is arranged in environmental cabinet, and such as, apertured on the tank wall of environmental cabinet 2, connecting line, the connection of this pipeline is supplied gas, at least one sent in vapour, air-supply and water injector.Apertured on the tank wall of described environmental cabinet, arranges the light fixture formation solar radiation regulating system that simulated solar irradiates in hole.Humidity sensor, air velocity transducer and solar radiation sensor are set in environmental cabinet.

Accordingly, in order to Reality simulation environment, except temperature control unit, be also provided with humidity controlling unit and control the keying of humidifier or add wet strength; Keying and flow that rainfall control module controls spray equipment are set; Keying and the rotating speed of blast velocity control unit controls fan are set, keying and brightness that solar radiation device control units controls bulb are set.These control device also can be arranged in ancillary test machine B simultaneously.

The control module of above-mentioned topworks can be included in control system D1, and its process flow diagram as is illustrated by figs. 11 and 12.

If increase the simulation of solar radiation, can perforate on environmental cabinet, bulb is set.

The incidence relation of each control module and computing machine D is described as follows for solar radiation: the switch of bulb is topworks, correspondingly, in environmental cabinet, solar radiation sensor is set, in control system D1 or arrange solar radiation control module association switch individually, this solar radiation control module is controlled by again the true environment parameter that sets in computing machine D and performs the operation such as closed and disconnected and strong and weak adjustment.

The comparing result that computing machine D gathers according to the parameters of the true environment simulation system of setting and related sensor, to each control module instruction, or starts or stops each topworks or adjusts its degree.Thus, various true environment can be simulated in environmental cabinet, allow the various tests of test specimen carry out in specific environment.

Computing machine D comprises the information of temperature sensor, displacement/deformation-sensor and strain gauge by gathering, test function as shown in fig. 13 that can be carried out: restraint stress, free variable, elastic modulus, distortion separation and concrete creep, if test block be directly by pouring concrete in testing machine, the overall process that ftractures of test and evaluation just can carry out from being solidified to to(for) concrete.

In the present invention, climate control system main in Reality simulation environmental system, can have two parts, and a part arranges on environment casing, and another part is arranged in the accommodating stationary installation of test specimen.Environmental cabinet is arranged, is more the temperature in Reality simulation environment, and arranges in the accommodating stationary installation of test specimen, the temperature of such as concrete dam in true environment can be simulated at short notice.So comprehensively climate control system is not all had in test unit of the prior art.

In the present invention, can directly by pouring concrete in the concrete sample accommodation space of the accommodating stationary installation of test specimen, like this, just can test concrete from lean state to solidifying again to the sclerosis dilatational strain of overall process and the change of stress in the true environment of simulation, such test for such as dam from build, be solidified to sclerosis overall process stress, strain can test under difficult environmental conditions, obtain comprehensive data, for the design of dam, construction provide valuable information.The test yet not accomplishing this overall process all do not expected by test unit of the prior art.Certainly, the accommodating stationary installation of test specimen in test unit provided by the invention also can be tested the concrete sample made.

As shown in Figure 1, ancillary test machine F in test unit provided by the invention, comprise an environmental cabinet, namely a test specimen accommodating cavity is comprised for the identical test specimen of the test specimen placed with test in described master trip machine, as an embodiment, in this test specimen accommodating cavity, described temperature control equipment is set, humidity control apparatus, solar radiation regulating device, rainfall regulating device and wind-speed adjusting device are also set; Set temperature sensor in this test specimen accommodating cavity, humidity sensor, solar radiation sensor, rainfall sensor and air velocity transducer are also set, sensor described in each is connected with described computing machine, and this control system D1 connects described regulating device and regulates the accommodating the cavity environment parameter of described test specimen identical with described master trip environmental cabinet; Displacement/deformation-sensor is also set in this test specimen accommodating cavity with the distortion of perception test specimen.

Environmental parameter in ancillary test case is identical with master trip case, the bottom surface that one is placed test specimen is wherein set, make test specimen can Free Transform, wherein be provided with true environment simulation system, this simulation system at least comprises a temperature regulating system, and it is arranged on heating in described environmental cabinet and/or on test specimen or cooling device; Also comprise temperature sensor and displacement/deformation-sensor, described temperature sensor is arranged on described test specimen and/or in environmental cabinet; Described displacement/deformation-sensor is arranged on test specimen, identical with master trip case; Sensor described in each signal output part be associated with computing machine.

Ancillary test machine and under test specimen and the enough little condition of machine bed plate friction factor, measure the Free Transform with auxiliary test specimen under the synthermal condition of master trip machine, synthermal condition parallel experiment machine, makes test figure possess integrality.

Test unit provided by the invention, is realized in the following manner based on the concrete cracking overall process test unit of true environment and method:

(1) under concrete test test specimen completes and relevant device is ready to complete condition, start-up simulation machine control system and computing machine, carry out relative parameters setting; Open true environment simulation system, fill in the parameters such as the on-site monthly mean temperature of engineering, water temperature, cloud amount, fine day solar radiant heat, cloud amount, latitude and concrete surface coefficient of heat emission, the simulation starting Related Environmental Factors is needed, environment temperature/humidity/rainfall/wind speed/solar radiation according to test;

(2) computing machine records concrete temperature according to each sensor, displacement and distortion, draw the concrete free variable under true environment simulated conditions, the concrete operations of measuring Free Transform can be: test specimen is fixed between fixed chuck and active chuck, due to changes such as temperature, when expanding or shrinking appears in test specimen, namely the strain gauge arranged demonstrates stress value, namely control system starts propulsion system, straight-line motion mechanism is made to move until strain gauge display stress value is zero in the direction that deformation direction is identical, Free Transform amount is now obtained from displacement/deformation-sensor, surveying free variable is the (temperature deformation of concrete various deformation, autogenous volumetric deformation with creep) carry out being separated making preparation,

(3) by computing machine, control system as temperature control unit, displacement/deformation control unit, Loading Control unit and respective sensor, the Free Transform of test specimen movable terminal is controlled, according to Free Transform and the distortion controlling reduction, concrete temperature stress under can recording true environment simulated conditions in different degree of restraint situation of each moment, comprise stress when making displacement be reduced to zero, the temperature stress namely under staff cultivation condition;

(4) by computing machine, control system as temperature control unit, displacement/deformation control unit, Loading Control unit and respective sensor, the Free Transform of test specimen movable terminal is once controlled, every certain time interval, displacement/distortion is made and once changes, gather corresponding STRESS VARIATION simultaneously, draw the elastic modulus in this moment, so repeatedly, concrete can be obtained under true environment simulated conditions at the elastic modulus of whole evolution;

(5) according to temperature variation Δ T (t) that thermal expansion coefficient of concrete α and data acquisition system (DAS) obtain, concrete pure temperature deformation under can drawing true environment simulated conditions, in conjunction with the Free Transform recorded, can show that other are out of shape, mainly comprise autogenous volumetric deformation and dry-shrinkage deformed;

(6) according to the modulus of elasticity of concrete recorded and Free Transform, can calculate under true environment simulated conditions by concrete stress during Creep Effect, start-up simulation machine control system, displacement/deformation control unit, Loading Control unit and corresponding sensor, concrete deformation is controlled, make it be deformed into zero, the difference of stress when at this moment recording stress and be not subject to Creep Effect is then the stress caused of creeping under true environment simulated conditions;

(7) data handling system is started, in conjunction with all test figures and data and curves, when occurring Stress and displacement curve occurring sudden change, represent concrete cracking, the concrete associated temperature in this moment, stress, displacement and deformation parameter can as the cracking indexs under real-world temperature condition, for crack-resistant performance of concrete evaluation provides test reference.

The described concrete operations freely retrained are: the two ends of concrete sample clamp by test unit, one end is fixed, one end can control mobile, under true environment simulated conditions, concrete can not added load by control end, by the computer control system of setting-up time interval (t), displacement/Deformation control system and loading system, make its free displacement be μ (t), be concrete free variable ε (t) of t.

The concrete operations of described restraint stress are: the two ends of concrete sample clamp by test unit, one end is fixed, one end can control mobile, under true environment simulated conditions, the free displacement of concrete sample movable terminal is μ (t), according to actual needs, by computer control system, displacement/deformation control unit and loading system, the displacement of test specimen movable terminal is reduced, at this moment described strain gauge record different degree of restraint of each moment be constraint factor f (t) situation under concrete temperature stress σ (t);

The displacement that movable terminal reduces is:

f(t)×μ(t)(6)

In formula, t is the time, and f (t) is concrete constraint factor during t, and μ (t) is the free displacement of concrete sample movable terminal.

Described elastic modulus concrete operations are: particularly, set interval in computer control system, every the time interval, by displacement control system, a change in displacement is done to test specimen movable terminal, measure according to strain gauge the STRESS VARIATION that this change in displacement causes, elasticity modulus test is carried out to this test specimen.

Every the △ t time, by displacement/Deformation control system, to movable terminal, change in displacement Δ μ (t) is done to test specimen and loading system, draw distortion Δ ε (t), be Δ σ (t) according to the STRESS VARIATION amount that strain gauge is measured, then the modulus of elasticity of concrete of t is:

$E\left(t\right)=\frac{\mathrm{\Δ}\mathrm{\σ}\left(t\right)}{\mathrm{\Δ}\mathrm{\ϵ}\left(t\right)}---\left(7\right)$

According to the time interval of design, computer control system automatically measures not modulus of elasticity of concrete in the same time, can obtain the elastic modulus of concrete in whole evolution.

The separation concrete operations of described distortion are: first do free constraint: concrete sample one end is fixed by test unit, other end retractable, the true environment of setting is provided by true environment simulation system, free variable test is carried out to this test specimen, in the time zone (t) of setting, the setting period gathers deflection ε (t).

After the 1 day length of time of concrete, its thermal expansivity would not change substantially again, and be commonly considered as a constant, this parameter also can be recorded by special hot expansion coefficient tester, thinks constant α here.According to temperature variation Δ T (t) that thermal expansion coefficient of concrete α and temperature control system record, concrete temperature deformation under true environment simulated conditions can be drawn:

Δε _T(t)＝α·ΔT(t)(8)

In conjunction with Free Transform ε (t) recorded, be separated, other distortion Δs ε can be drawn _at (), mainly comprises autogenous volumetric deformation and dry-shrinkage deformed:

Δε _a(t)＝ε(t)-Δε _T(t)(9)

Described concrete creep concrete operations are: according to modulus of elasticity of concrete E (t) recorded and Free Transform ε (t), can to calculate under true environment simulated conditions by concrete stress σ (t) during Creep Effect:

σ(t)＝ε(t)·E(t)(10)

Start concrete displacement control system, control concrete deformation, make it be deformed into zero, at this moment recording stress is σ ₀(t), then the stress caused of creeping under true environment simulated conditions is reduced to:

σ _c(t)＝σ(t)-σ ₀(t)(11)

Pass through σ _ct the size of () can draw the influence degree of concrete creep, wherein t is the time.

The concrete operations of described concrete cracking overall process are: concrete temperature changes to design temperature from initial temperature, test specimen two ends are fixed or are applied pulling force, when tension data reduce suddenly, displacement increases suddenly, corresponding time m-stress, time m-distortion/displacement curve on there is sudden change time, concrete cracking, obtain at this moment concrete correlation parameter, comprise temperature, tensile strength, limit stretch value.

The concrete operations evaluated are: the test figure and the result that combine A, B, C, D, E above, concrete temperature changes to setting degree, when tension data reduce suddenly, displacement increases suddenly, homologous thread there is sudden change time, concrete cracking, at this moment concrete correlation parameter temperature, stress, displacement and distortion can carry out concrete cracking overall process evaluation as to this test specimen.

Can set with the following method for true environment:

1. environment temperature

For locality situation and determine, namely Reality simulation environment is local, and above monthly mean temperature data is fitted to a cosine curve, following formula (1) is the computing formula after matching:

$T_a=T_{am}+A_a\cos \[\frac{\mathrm{\π}}{6}\left(\mathrm{\τ}-{\mathrm{\τ}}_0\right)\]---\left(1\right)$

In formula, T _afor temperature, T _amfor average temperature of the whole year, A _afor temperature year luffing, τ is time (moon), τ ₀for the time (moon) of maximum temperature.

Consider temperature diurnal variation, adopt following formula to calculate:

$T_a^d=T_a+Acos\[\frac{\mathrm{\π}}{12}(t-14)\]---\left(2\right)$

In formula, for daily temperature, T _afor monthly mean temperature, A is temperature diurnal variation amplitude, t be moment in 1 day (time) determine according to the Various Seasonal of different regions.

2. solar radiant heat

Concrete structure is often exposed under solar radiation, and it has material impact to concrete temperature.The heat that in unit interval inherent unit area, solar radiation comes is S, and wherein set the part that absorbed by concrete as R, remainder is reflected, then:

R＝α _s·S(3)

In formula, α _sfor absorption coefficient, also referred to as coefficient of blackness, concrete surface generally gets 0.65.

S＝S ₀(1-kn)(4)

In formula, S ₀for fine day solar radiant heat, n is cloud amount, and k is coefficient, and these three numerical value are provided by local weather station;

The temperature that the impact at sunshine is equivalent to surrounding air increases Δ T _a,

ΔT _a＝R/β(5)

In formula, β is concrete surface coefficient of heat emission, calculates according to surface roughness and wind speed.

3. rainfall

The rainfall amount of inquiry engineering location meteorological department, carrys out simulated rainfall by rainfall equipment and rainfall amount controller.

4. wind speed

The wind speed of the inquiry on-site meteorological department of engineering, threshold wind velocity analogue means, to draw concrete surface coefficient of heat transfer according to wind speed.

A concrete test example is as follows:

Use above-mentioned test method and test unit to test concrete test block, verify based on the concrete cracking overall process test unit of true environment and the validity of method and rationality.Test ambient temperature value is the temperature measured value of nearly a year of certain Practical Project, input computing machine, enable test unit, make experimental enviroment completely according to this actual measurement temperature Change, test is under this ambient air temperature condition, the STRESS VARIATION situation of concrete test block, studies the concrete cracking overall process based on true environment.

As can be seen from testing the test figure drawn, ambient air temperature meets the sinusoidal variations rule of engineering reality, energy actual response Practical Project environment; Can reflect real variation of stress based on the test temperature stress under this ambient air temperature condition, with Temperature cycling fluctuation, based on the effect of expanding with heat and contract with cold, environment temperature rising, concrete compressive stress increase; Environment temperature reduces, concrete compressive stress reduces tension and increases, and sees Figure 14.

Claims (6)

1., based on a concrete cracking overall process test unit for true environment, it is characterized in that: comprise a base, be provided with on the base:

One environmental cabinet, at least has wall and upper cover, forms a closed space, separates with surrounding environment;

One concrete sample accommodating device, it is arranged in this environmental cabinet, comprise fixed bolster plate in the middle part of fixed chuck, active chuck, test specimen, three's split forms a concrete sample accommodation space that upper end is uncovered or upper and lower side is all uncovered, described fixed chuck is fixedly installed in this environmental cabinet, and described active chuck can be arranged movably along the axis of the length direction of described concrete sample accommodation space;

At described environmental cabinet or described environmental cabinet and concrete sample accommodation space set temperature sensor;

One true environment simulation system, it at least comprises a temperature control equipment, and be heating and/or cooling device, it is arranged in described environmental cabinet and concrete sample accommodating device to propose fixed true environment at temperature patrix;

One loading system, comprise a framework, a gearing and propulsion system, described framework is arranged on described base, this gearing comprises a straight-line motion mechanism, driven member is wherein fixed by the sidewall entered environment case of described environmental cabinet and described active chuck and this active chuck position is fixed or moves at described axis direction, and the driving link in this straight-line motion mechanism is fixing on the frame; Described propulsion system are arranged on said frame, connect this driving link in described straight-line motion mechanism;

Described active chuck or the parts that are connected with active chuck arrange the distortion of displacement/deformation-sensor perception concrete sample; Described straight-line motion mechanism arranges the load that strain gauge perception test specimen bears.

2. test unit according to claim 1, it is characterized in that: the shape of cross section of described accommodation space is: two ends are the shorter heads of width greater depth, centre is the interlude that width smaller length is longer, and described head is connected transition with interlude by cone section; Splicing seams in the middle part of described fixed chuck and active chuck and test specimen between fixed bolster plate is positioned at the interlude scope of this accommodation space; And/or the accommodating stationary installation of described test specimen also comprises a cope match-plate pattern, its described upper end closing described concrete sample accommodation space is uncovered; And/or,

Seam between described side template and described active chuck and/or fixed chuck leaves gap, this gap comprises the gap between the termination of side template and described active chuck, to ensure test specimen side template and active chuck non-contravention when compressing, and/or comprise the gap between the side of side template and fixed chuck and active chuck; And/or,

Described side template can be arranged in this environmental cabinet transverse shifting.

3. test unit according to claim 1 and 2, it is characterized in that: described true environment simulation system also comprises at least one regulating device arranged in described environmental cabinet: humidity control apparatus, solar radiation regulating device, rainfall regulating device, wind-speed adjusting device, correspondingly, also comprise as at least one in lower sensor: humidity sensor, solar radiation sensor, rainfall sensor and air velocity transducer.

4. according to the test unit one of claims 1 to 3 Suo Shu, it is characterized in that: be arranged on heating in the described climate control system in described environmental cabinet and/or cooling device is: be arranged in the tank wall of described environmental cabinet or in the space closed, described tank wall has hollow chamber, and/or, arrange described fixed chuck, active chuck and side template in the accommodating stationary installation of test specimen at least one there is hollow chamber;

Each described hollow chamber arranges import and is communicated with the medium channel of described heating or cooling device with outlet, described topworks is the discharge pump of the electrical heating coil arranged on the medium channel of this heating and/or cooling device or the media flow driving heating or cooling, in test providing heat energy or cold energy as required.

5. test unit according to claim 3, it is characterized in that: apertured on the tank wall of described environmental cabinet, connecting line, the connection of this pipeline is supplied gas, at least one sent in vapour, air-supply and water injector, correspondingly forms humidity control apparatus, rainfall regulating device and wind-speed adjusting device; And/or apertured on the tank wall of described environmental cabinet, arranges the light fixture formation solar radiation regulating device that simulated solar irradiates in hole.

6. according to the test unit one of claim 1 to 5 Suo Shu, it is characterized in that: described framework is the framework of the rectangle comprising two crossbeams and two column formations, a fixed cross beam is fixed on the described base of described fixed chuck side, two described columns described fixed cross beam that is connected abreast is positioned at described environmental cabinet both sides, a fine motion crossbeam is arranged on the described base of described active chuck side, be connected with described column, described propulsion system are arranged on this fine motion crossbeam, form reaction frame thus, described straight-line motion mechanism is connected with active chuck through this fine motion crossbeam, the support section of described displacement/deformation-sensor and described strain gauge is fixed on described base directly or indirectly, and/or,

In the described framework that two described crossbeams and two described columns are formed, the material of described column and sectional dimension are: ensure that its rigidity is the 5-20 power doubly of bearing the maximum strength stress of concrete and indeformable, or stiffness K is more than or equal to 2MN/mm; And/or its temperature deformation is less than 10 microns when ensureing that its temperature stability is in the temperature range-20-80 DEG C tested; And/or,

The described case lid of described environmental cabinet arranges form, makes process of the test visual; And/or,

Described propulsion system are servomotor, connect worm reduction gear; And/or,

Described straight-line motion mechanism adopts screw-drive mechanism; And/or,

At described base, one hoisting gear is also set, a base plate is set in the accommodating stationary installation of described test specimen for placing test specimen or pouring into a mould test specimen thereon, this base plate connects this hoisting gear, by running this hoisting gear, can will move in test specimen or shift out concrete sample accommodation space.