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

Abstract

The invention provides a concrete cracking whole process test device based on the real environment, which includes a base on which: an environmental chamber is separated from the surrounding environment; a concrete specimen accommodating device is arranged in the environmental chamber, including fixing The chuck, the movable chuck, and the fixed side formwork in the middle of the specimen are combined to form a concrete specimen storage space, the fixed chuck is fixed in the environmental chamber, and the movable chuck is movably set; the environmental chamber and the concrete specimen are accommodated A temperature sensor is installed in the space; a real environment simulation system, which at least includes a temperature adjustment device arranged in the environmental box and the concrete specimen holding device to simulate the real environment set in temperature; a loading system, so that the position of the movable chuck Fixed or moved in the axial direction, a displacement/deformation sensor is set on the movable chuck to sense the deformation of the concrete specimen; a stress sensor is set to sense the load borne by the specimen. The device can test the whole process of the development of factors such as temperature and stress of concrete under variable environmental conditions from the perspective of testing.

Description

Experimental device for the whole process of concrete cracking based on real environment

technical field

The invention belongs to the technical field of water conservancy and hydropower engineering, and relates to a method for testing the whole process of cracking of concrete based on a real environment and a test device using the method, more specifically, a device for the simulation test of the whole process of cracking of large-volume concrete.

Background technique

For a long time, "no dam, no crack" has been an unsolved problem in the world. The appearance, performance and safety of the dam structure are affected by the appearance of cracks, and ultimately affect people's lives and properties. How to reduce or even prevent cracks has become a problem that project builders must consider. With the advancement of theoretical and technical research in related fields, the research work on dam concrete cracks has made significant progress, especially the temperature control and crack prevention of large-volume concrete. At present, a relatively complete basic theory and method system has been formed. However, in view of the complexity of water conservancy and hydropower projects, especially the harsh environment in the area, the problem of dam concrete cracks has not been completely resolved.

There are many factors that lead to cracks in concrete, and structural, material and construction factors may all be the cause of cracks. However, for dams, especially those built in areas with large temperature differences and high altitudes, the surrounding meteorological environment has gradually become a temperature-controlled environment. The key factor of anti-crack control. The atmospheric environment not only surrounds the entire concrete project in real time, but also the vagaries of the atmospheric environment have an important impact on the project, especially the temperature, humidity, rainfall, wind speed and solar radiation of the surrounding environment, which seriously affect the generation of concrete cracks However, there is no conclusion yet on how the influence of atmospheric environmental factors on concrete cracks is, and how much their influence is. Therefore, it is necessary to develop a concrete cracking process test device and method based on the real environment.

Contents of the invention

The purpose of the present invention is to improve the limitations and deficiencies in the existing concrete temperature stress simulation and crack research, and provide a method for testing the whole process of the development of factors such as the temperature and stress of concrete under variable environmental conditions from the perspective of testing. device.

Technical solution of the present invention is:

The whole process test device for concrete cracking based on the real environment provided by the present invention includes a base on which:

An environmental chamber, having at least four walls and a top cover, forming a closed space, separated from the surrounding environment;

A concrete specimen accommodation device, which is arranged in the environmental chamber, and includes a fixed chuck, a movable chuck, and a fixed side formwork in the middle of the specimen. The three are combined to form a concrete specimen with an open upper end or an open upper and lower end. The accommodating space of the concrete specimen, the fixed chuck is fixedly arranged in the environmental chamber, and the movable chuck can be moved along the axis of the length direction of the accommodating space of the concrete specimen;

A temperature sensor is set in the environmental chamber or the accommodating space between the environmental chamber and the concrete specimen;

A real environment simulation system, which at least includes a temperature adjustment device, which is a heating and/or cooling device, which is arranged on the environmental box and the concrete specimen holding device to provide at least a real simulation setting in temperature. environment;

A loading system, including a frame, a transmission device and a power device, the frame is arranged on the base, the transmission device includes a linear motion mechanism, and the driven part enters the environment through the side wall of the environmental box The box is fixed to the movable chuck so that the movable chuck is fixed in position or moves in the direction of the axis, the active part in the linear motion mechanism is fixed on the frame; the power device is arranged on the frame, connected The active part in the linear motion mechanism;

A displacement/deformation sensor is arranged on the movable chuck or a part connected with the movable chuck to sense the deformation of the concrete specimen; a stress sensor is arranged on the linear motion mechanism to sense the load borne by the specimen.

Matching with the test device, it also includes a computer, which is connected to a control system through a data line, and the control system includes: a control unit for controlling the action of each actuator in the real environment simulation system of the main testing machine; A control unit that controls the action of the power device in the concrete specimen loading system;

The computer also uses the signal output terminal of the temperature sensor for monitoring environmental parameters through the data line;

The signal output end of the displacement/deformation sensor for monitoring the displacement/deformation of the concrete specimen;

The signal output end of the stress sensor for monitoring the stress of the test piece is connected;

The control signal output terminal of the control system is connected with the control terminal of each actuator.

The temperature control unit accepts the instructions of the computer and controls the actuator, that is, the heating/cooling device to work, so that the temperature of the concrete specimen accommodation space, including the environmental chamber, meets the set parameters.

The displacement/deformation control unit and the loading control unit together control the actuator, that is, the power device in the loading system.

The data processing system in the computer calculates and outputs at least one result of the concrete specimen in the simulated real environment, including constraint stress, free variable, elastic modulus, deformation separation, and creep.

The cross-sectional shape of the accommodating space is as follows: both ends are heads with a larger width and a shorter length, and the middle is a middle section with a smaller width and a longer length, and the head and the middle section are connected and transitioned by a tapered section; The splicing seam between the fixed chuck and the movable chuck and the fixed side template in the middle of the test piece is located in the middle section of the accommodating space.

Further, the test piece accommodating and fixing device may also include an upper formwork, which closes the upper end opening of the concrete test piece accommodating space.

There is a gap at the seam between the side template and the movable clamp and/or the fixed clamp, and the gap includes the gap between the end of the side template and the movable clamp to ensure that the test piece is compressed When the side template does not conflict with the movable chuck, it also includes the gap between the side of the side template and the fixed chuck and the movable chuck.

The side templates are arranged in the environmental box so as to be movable laterally.

In use, the concrete can be directly poured into the concrete specimen accommodating space to form a test piece, and the prepared test piece matching the shape of the test piece accommodating space can also be placed in the concrete test piece accommodating space. in space.

The heating and/or cooling device in the air temperature control system arranged in the environmental chamber may be arranged in a wall of the environmental chamber or in a closed space, the wall of the chamber has a hollow chamber, and/or Or, at least one of the fixed chuck, the movable chuck and the side template in the test piece accommodating and fixing device has a hollow chamber;

Each of the hollow chambers is provided with an inlet and an outlet to communicate with the medium passage of the heating or cooling device, and the actuator can be an electric heating coil arranged on the medium passage of the heating and cooling device or drive the flow of the heating or cooling medium The transfer pump is used to provide heat or cold energy as needed during the test.

In the present invention, the main air temperature control system in the simulated real environment system may have two parts, one part is set on the environmental box, and the other part is set on the test piece accommodating and fixing device. The setting on the environmental chamber is more to simulate the air temperature in the real environment, while the setting on the specimen holding and fixing device can simulate the temperature in the real environment such as a concrete dam in a short time. There is no such comprehensive air temperature control system in the test device in the prior art.

In the present invention, the concrete can be poured directly in the concrete specimen accommodation space of the specimen accommodation and fixing device, so that the concrete can be tested in the simulated real environment from dilute state to solidification and then to the complete process of hardening Expansion deformation and stress changes, so that, for example, the stress and strain of the dam from pouring, solidification to hardening can be tested under different environmental conditions, and comprehensive data can be obtained to provide valuable information for the design and construction of the dam . The testing devices in the prior art have not thought of and can't do the test of this complete process. Of course, the specimen accommodating and fixing device in the test device provided by the present invention can also test the concrete specimens that have been manufactured.

The computer control system provided by the present invention is basically the prior art, in which the following functions are realized: when the test piece is pushed against the movable chuck due to the deformation in the simulated real environment, the stress sensor collects the stress, and through data processing The signal output terminal of the system and data output system is connected with the power device to start the power device to drive the movable chuck to move until the stress sensed on the stress sensor decreases to zero, and the power device stops.

Such a structure can enable the test device to realize tests such as free variables.

In addition, after the free variable, start the power device to drive the movable chuck to move to reduce the amount of deformation, the displacement is obtained by the displacement sensor, and the corresponding stress value is obtained by the stress sensor.

In addition to the air temperature adjustment device, the real environment simulation system may also include at least one adjustment device in the environmental chamber: a humidity adjustment device, a solar radiation adjustment device, a rainfall adjustment device, and a wind speed adjustment device. Specifically, at least one of the following sensors is also included: a humidity sensor, a solar radiation sensor, a rainfall sensor and a wind speed sensor, which are connected to the computer and the actuator connected to the control system.

Specifically, holes can be set on the wall of the environmental box to connect pipelines, and the pipelines are connected to at least one of air supply, steam supply, air supply and water spraying devices, and correspondingly constitute humidity adjustment devices, rainfall adjustment devices, etc. device and wind speed regulating device; and/or, a hole is provided on the wall of the environmental chamber, and a lamp for simulating solar irradiation is arranged in the hole to form a solar radiation regulating device.

The individual actuators are associated with the control system so that the set real environment is simulated.

Each of the regulating devices can also be a self-contained system, such as a temperature regulating device, including a heating controller and a temperature controller, which are connected to a heating element and a temperature sensor to realize the heating function. In this way, the structure of the control system can be simplified.

Further, the frame is a rectangular frame composed of two beams and two uprights, one fixed beam is fixed on the base on one side of the fixed chuck, and the two uprights are fixed in parallel to the The fixed crossbeam is located on both sides of the environmental chamber, a micro-movement crossbeam is arranged on the base on one side of the movable chuck, and is connected with the column, and the power device is arranged on the micro-movement crossbeam, thus forming The reaction force frame, the linear motion mechanism is connected to the movable chuck through the micro-movement beam, and the supporting part of the displacement/deformation sensor and the stress sensor is directly or indirectly fixed on the base.

In the frame provided by the present invention, one of the two beams is fixed on the base to form a fixed beam, and the other is only arranged on the base and has no fixed structure with the base to form a micro-moving beam, and the loading system is arranged on the micro-moving beam.

In this way, when the loading system applies force to the test piece, the frame will bear a large stress and may have a small deformation, but this force and deformation will not be transmitted to the base. Therefore, the measurement accuracy of the displacement sensor and the force sensor is not affected by the deformation of the frame, ensuring good measurement accuracy.

The material and cross-sectional size of the column are: to ensure that its stiffness is 5-20 times the maximum strength stress of the concrete without deformation, or the stiffness K is greater than or equal to 2MN/mm; and/or, to ensure that its temperature stability is In the temperature range of the test (eg -20-80°C), the temperature difference deformation is less than 10 microns.

The frame provided by the present invention adopts the column and beam type, and has a stable structure. In addition, the columns therein have sufficient rigidity and temperature difference deformation stability, which can well ensure the accuracy of the test.

Further, a viewing window is provided on the cover of the environmental chamber, so that the test process can be visualized.

The power device is preferably a servo motor, which is connected to a transmission mechanism of a worm gear reducer. Such a power device greatly improves control precision, feedback speed and efficiency.

The linear motion transmission mechanism adopts a screw transmission mechanism.

A lifting mechanism is also set on the base, and a base plate is set in the test piece accommodating and fixing device for placing the test piece or pouring the test piece on it, the base plate is connected with the lifting mechanism, and by running the lifting mechanism, it can Move the test piece in or out from the concrete test piece holding space.

An auxiliary testing machine may also be included in the testing device provided by the present invention, and the auxiliary testing machine includes a test piece accommodating cavity for placing the same test piece as the test piece tested in the main testing machine, and the test piece holds The temperature adjustment device is arranged in the chamber, or at least one of the temperature adjustment device and the following adjustment devices is arranged: a humidity adjustment device, a solar radiation adjustment device, a rainfall adjustment device and a wind speed adjustment device; A temperature sensor is set, and at least one of the following sensors is also set: a humidity sensor, a solar radiation sensor, a rainfall sensor and a wind speed sensor, each of which is connected to the computer, and the control system is connected to the adjustment device to adjust the test. The environmental parameters in the piece accommodating cavity are the same as those of the main test environment box; a displacement/deformation sensor is also set in the test piece accommodating cavity to sense the deformation of the test piece.

The control system also includes a control unit for controlling the actions of various actuators of the real environment simulation system in the auxiliary testing machine.

The same test piece as in the main test device is put into the test piece accommodating cavity, so that the test piece can be deformed freely. The test piece in the same environment in the auxiliary testing machine is used for comparison with the test piece in the main test device. The auxiliary testing machine measures the free deformation of the auxiliary test piece at the same temperature as the main testing machine under the condition that the friction coefficient between the test piece and the machine bottom plate is small enough. Parallel testing machines under the same temperature conditions make the test data complete.

The test device provided by the invention is mainly used for concrete crack mechanism and temperature stress test. Under the condition of various temperature control measures, the test of the development process of concrete's own temperature stress in the whole process from pouring to hardening can be carried out. This process can include the development of parameters such as adiabatic temperature rise, thermal expansion coefficient, elastic modulus and creep over time. It can also simulate the real meteorological environment, and simulate the temperature stress and cracking mechanism under the influence of natural factors. The test device can be set according to different temperature and constraint conditions, including adiabatic, constant temperature, set temperature rise and temperature drop process, etc. Through the simulation test of the whole process of concrete cracking, the crack resistance performance of concrete is evaluated.

Using the above-mentioned test device, the whole process test method of concrete cracking based on the real environment includes the following steps:

(1), concrete is poured in described concrete test piece accommodating space, perhaps concrete test piece is arranged on the fixing device in this concrete test piece accommodating space; The head and the movable chuck are fixed;

(2) Build a real environment simulation system, make at least the temperature parameter in the environment box and/or the concrete specimen holding device reach the real environment requirement to be simulated by the actuator, the environment in the environment box It can be a constant environment, or an environment in which parameters vary within a set range;

(3) Then carry out at least one of the following test steps in the set real environment:

A. Free constraints:

The test device fixes one end of the concrete specimen, and the other end is free to expand and contract. In the real environment provided by the real environment simulation system, the free variable test is carried out on the specimen. Within the set time zone (t), the set The deformation amount ε(t) is collected in time interval,

When the specimen expands or contracts, the set stress sensor will display the stress value, that is, start the power device, so that the linear motion mechanism will move in the same direction as the deformation direction until the stress sensor shows that the stress value is zero, obtained from the displacement/deformation sensor The value of the free variable at this time.

The specific operation of the free constraint is: the test device clamps the two ends of the concrete specimen, one end is fixed, and the other end can control the movement. Under the real environment simulation conditions, the controllable end of the specimen is not loaded, and the time interval is set ( t), according to the data detected by the displacement/deformation sensor and the stress sensor, the power device is activated through the control system, so that the free displacement of the specimen is μ(t), which is the free variable ε(t) of the concrete at time t ).

The purpose of measuring the free variables of concrete is to separate the various deformations of the concrete.

B. Constraint stress:

The test device clamps both ends of the concrete specimen, one end is fixed, and the other end can be moved under control, that is, the end of the specimen connected to the movable clamp is free to expand and contract, when the specimen has an elongation in the real environment or shrinkage, set the time interval (t), according to the data detected by the displacement/deformation sensor and the stress sensor, the power device is activated through the control system, so that the displacement of the movable end of the specimen is reduced, and different degrees of restraint are tested. Concrete stress under the condition, the restraint stress test was carried out on the specimen.

The specific operation is: the test device clamps both ends of the concrete specimen, one end is fixed, and the other end can be controlled to move. Under the conditions of real environment simulation, the free displacement of the movable end of the concrete specimen is μ(t). According to actual needs, the displacement of the movable end of the specimen is reduced through the computer control system, displacement/deformation control system and loading system , at this time, the stress sensor measures the concrete temperature stress σ(t) under the condition of different restraint degrees at each moment, that is, the restraint coefficient f(t).

The reduced displacement of the movable end is:

f(t)×μ(t)(6)

In the formula, t is time, f(t) is the concrete constraint coefficient at time t, and μ(t) is the free displacement of the movable end of the concrete specimen.

C. Modulus of elasticity:

The concrete cracking process test device based on the real environment measures the elastic modulus of concrete, and sets the time interval △t in the computer, that is, measures the elastic modulus of the concrete every △t time.

Specifically, set the time interval Δt in the computer, and at every Δt time interval, according to the data detected by the displacement/deformation sensor and the stress sensor, the power device is activated through the control system, so that the movable end of the specimen is displaced once Change, that is, for the set displacement change value (such as 2 microns), when the length of the test piece is extended or shortened to the set displacement change value (such as 2 microns), a displacement change is made to the movable end of the test piece. The set displacement change value is pressed back or pulled back, and the elastic modulus test is carried out on the specimen according to the stress change caused by the displacement change measured by the stress sensor.

The specific operation is: every △t time, according to the data detected by the displacement/deformation sensor and the stress sensor, the power device is activated through the control system, so that the movable end of the test piece makes a displacement change Δμ(t), which is The difference between the length of the previous moment and this moment of the specimen is the deformation Δε(t), which refers to the difference between the length of the specimen at the previous moment and this moment divided by the total length of the specimen, measured by the stress sensor The amount of stress change is Δσ(t), then the elastic modulus of concrete at time t is:

$\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

According to the designed time interval, the computer control system can automatically measure the elastic modulus of concrete at different times, and then the elastic modulus of the concrete in the whole development process can be obtained.

D. Deformation Separation

According to the thermal expansion coefficient of concrete and the temperature change measured by the temperature sensor, the temperature deformation of the concrete is obtained, combined with the measured free deformation, the deformation separation test of the specimen is carried out.

Deformation separation refers to the separation of the measured total deformation. Because the measured total deformation is a mixture of various deformations, including deformation caused by temperature (such as thermal expansion and contraction), deformation caused by drying shrinkage, autogenous volume deformation, deformation caused by force, and so on. The separation here, for example, separates the deformation caused by temperature alone from the measured deformation, so as to understand the deformation of concrete only under the action of temperature, etc.

The specific operation is as follows: First, do free constraints: the test device fixes one end of the concrete specimen, and the other end can be freely expanded and contracted. The real environment provided by the real environment simulation system is set for the free variable test of the specimen. In the area (t), set the time period to collect the deformation amount ε(t).

After the age of 1 day, the thermal expansion coefficient of concrete will basically not change, and it is generally considered to be a constant. This parameter can also be measured by a special thermal expansion coefficient tester, which is considered to be a constant α here. According to the concrete thermal expansion coefficient α and the temperature change ΔT(t) measured by the temperature control system, the temperature deformation of concrete under the real environment simulation conditions can be obtained:

ΔεT(t)＝α· _ΔT (t)(8)

Combined with the measured free deformation ε(t) and separated, other deformations Δε _a (t) can be obtained, mainly including autogenous volume deformation and drying shrinkage deformation:

Δε _a (t) = ε (t) - Δε _T (t) (9)

E. Concrete Creep

According to the elastic modulus of concrete measured in the aforementioned step C and the free deformation measured in the aforementioned step A, the stress of the concrete when not affected by creep can be calculated; according to the data detected by the displacement/deformation sensor and the stress sensor, the power is controlled by the control system. The device operates, so that the deformation of the specimen is zero, and another stress is measured at this time. According to the changes of these two stresses, the concrete creep test is carried out on the specimen.

The specific operation is: according to the obtained concrete elastic modulus E(t) and free deformation ε(t), the concrete stress σ(t) can be calculated under the simulated conditions of the real environment without being affected by creep:

σ(t)=ε(t)·E(t)(10)

According to the data detected by the displacement/deformation sensor and the stress sensor, the power device is activated through the control system, thereby controlling the deformation of the concrete to make it zero. At this time, the measured stress is σ ₀ (t), and the real environment simulation The stress reduction caused by creep under the condition is:

σ _c (t) = σ (t) - σ ₀ (t) (11)

The degree of influence of concrete creep can be obtained by the size of σ _c (t), where t is time.

F. The whole process of concrete cracking

Let the concrete specimen bear the tensile stress in the set temperature change or apply the tensile force in the set simulated real environment until it cracks, and obtain the temperature change of the concrete crack or the tensile strength of the concrete specimen in the set real environment or ultimate stretch value.

The specific operation of the whole process of concrete cracking can be: the concrete temperature changes from the initial temperature to the set temperature, the two ends of the specimen are fixed, and the tensile force is applied to one end. When the tensile stress data suddenly decreases and the displacement suddenly increases, the corresponding time-stress, When a sudden change occurs on the time-deformation/displacement curve, the concrete cracks, and the relevant parameters of the concrete at this time are obtained, including temperature, tensile strength, and ultimate tensile value.

G. Evaluate the whole process of concrete cracking on the specimen

Combining the test data of steps A, B, C, D, E, and F, that is, the test conditions and results, perform performance evaluation on the concrete specimen in the simulated real environment set by the test.

Further, in combination with the test data and results of at least one of A, B, C, D, E, and F above, that is, in combination with relevant environmental parameters of concrete such as temperature, stress, displacement and deformation, the test piece is carried out from the concrete test piece Intact or the whole process from pouring to cracking.

In this step, a variety of environmental factor change models can be set according to the characteristic of complex meteorological environment changes in engineering practice. The environmental factor parameters include ambient temperature, and at least one of humidity, rainfall, wind speed and solar radiation. .

The relevant parameters of concrete temperature, stress, displacement and deformation can be used as cracking indicators under real ambient temperature conditions, providing important test references for engineering design, construction and construction.

As can be seen from the above, the described test device and method can test the free deformation of concrete under real environmental conditions; can test the temperature stress of concrete under different restraint states under real environmental conditions; can test the elastic modulus of concrete under real environmental conditions. It can carry out tests on the process of quantitative development; it can conduct separate tests on various deformations of concrete under real environmental conditions; it can test the creep of concrete under real environmental conditions; The development process and cracking process of parameters, etc., analyze and evaluate the whole process of concrete cracking, and provide reference for the anti-cracking design of concrete.

The simulation of the real environment refers to simulating the real engineering meteorological environment by inputting relevant information such as ambient temperature, humidity, rainfall, wind speed and solar radiation according to the hydrometeorological conditions of the actual project location. In this step, a variety of environmental factor change models can be set according to the characteristic of complex meteorological environment changes in engineering practice.

The method provided by the present invention can also be tested and evaluated at various stages or aspects of the whole process from the concrete pouring test piece until cracking.

In the above method, for the simulation of the real environment, the following methods can be used:

①Ambient temperature

According to the local situation, that is, to simulate the real environment, the average temperature data of the previous month is fitted into a cosine curve. The following formula (1) is the calculation formula after fitting:

Considering the annual change of temperature, the following formula is used for calculation:

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; \&lsqb;</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula, T _a is the temperature, T _am is the annual average temperature, A _a is the annual temperature variation, τ is the time (month), and τ ₀ is the time (month) when the temperature is the highest.

Considering the diurnal variation of temperature, the following formula is used for calculation:

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; \&lsqb;</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 12</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 14</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In the formula, is the daily temperature, T _a is the monthly average temperature, A is the daily variation range of the temperature, and t is the time (hour) in a day, which depends on different seasons in different regions.

② Solar radiation heat

Concrete buildings are often exposed to solar radiation, which has a significant effect on the concrete temperature. The heat radiated by the sun on a unit area per unit time is S, where the part absorbed by the concrete is R, and the rest is reflected, then:

R＝α _s S(3)

In the formula, α _s is the absorption coefficient, also known as the blackness coefficient, and the concrete surface is generally taken as 0.65.

S=S ₀ (1-kn)(4)

In the formula, S ₀ is the solar radiant heat on sunny days, n is the cloud amount, and k is the coefficient, and these three values can be given by the local weather station.

The impact of sunshine is equivalent to the increase of the temperature of the surrounding air by ΔT _a ,

ΔT _a =R/β(5)

In the formula, β is the heat dissipation coefficient of the concrete surface, which can be calculated according to the surface roughness and wind speed.

③Rainfall

Query the rainfall of the meteorological department where the project is located, and simulate rainfall through rainfall equipment and rainfall controllers.

④ wind speed

Query the wind speed of the meteorological department where the project is located, start the wind speed simulation device, and obtain the heat dissipation coefficient of the concrete surface according to the wind speed.

The test device for the whole process of concrete cracking based on the real environment provided by the present invention can carry out the development process of the concrete's own temperature stress in the whole process from pouring to hardening under the condition of various temperature control measures, including adiabatic temperature rise, thermal expansion coefficient, elastic modulus, etc. It can also simulate the real meteorological environment and simulate the temperature stress and cracking mechanism under the influence of natural factors. The device can set different temperature and constraint conditions according to needs, including adiabatic, constant temperature, set temperature rise and fall process, etc. Through the simulation test of the whole process of concrete cracking, the crack resistance performance of concrete is evaluated.

The device and method have the following advantages:

1) This test device adopts the dual structure of environmental chamber and concrete specimen storage space, which can start the test from the pouring of the specimen, and can simulate various real environments, so as to fully understand the complete process from pouring to hardening of concrete, and serve various industries Concrete structures are given comprehensive test data.

2) A high-rigidity reaction frame structure is adopted, which is suitable for long-term concrete creep tests.

3) A floating frame structure is adopted, that is, beams at both ends, one is fixed on the base, and the other is only placed on the base, so the measurement accuracy is higher and the system error is smaller.

4) The automatic lifting device of the test piece is added to save energy and facilitate the operation of the test piece after forming and testing the test piece;

5) Added the function of adjusting the constraints of the specimen during the test, adjusting the fine-tuning mechanism during the test can gradually reduce the constraints of the specimen to zero;

6) Real-time tracking and recording data, the sampling interval can be set freely;

Therefore, this device is an ideal cost-effective test equipment widely used in mining, mining, underground engineering, metallurgical construction, national defense and civil air defense, colleges and universities, transportation and other industries.

The present invention will be further described in detail through the accompanying drawings and examples below.

Description of drawings

Figure 1 is a schematic structural view of the test device provided by the present invention.

Fig. 2 is a structural schematic diagram of the external structure of the main testing machine in the testing device provided by the present invention.

Fig. 3 is a structural schematic diagram of the internal structure of the main testing machine provided by the present invention.

FIG. 4 is a schematic diagram of a partially enlarged structure of part A of FIG. 3 .

FIG. 5 is a top structural schematic view of the main testing machine shown in FIG. 3 after the box cover 22 and the upper template 314 of the environmental box are removed.

FIG. 6 is a schematic diagram of a partially enlarged structure of part A of FIG. 5 .

Fig. 7 is a schematic diagram of the structure of the displacement sensor.

Fig. 8 is a schematic diagram of the structure of the medium circulation circuit in the side formwork.

Figure 9 is a schematic diagram of the medium heating process.

Fig. 10 is a structural schematic diagram of an embodiment of the heating device.

Fig. 11 is a control principle diagram of the whole process test of concrete cracking based on the real environment of the present invention.

Fig. 12 is another control principle diagram.

Fig. 13 is a functional schematic diagram of the present invention.

Figure 14 is the air temperature and concrete stress process line based on the real environment.

detailed description

The concrete cracking whole process test device based on the real environment provided by the present invention is shown in FIG. 1 , including a main testing machine A and an auxiliary testing machine B. Also be provided with computer D, computer D is connected with a control system D1 through data line L, and this control system D1 comprises:

1. The control unit for controlling various actuators of the real environment simulation system in the main testing machine A and auxiliary testing machine B;

2. The control unit of the actuator in the main testing machine A that controls the loading of the concrete specimen is the control unit of the power device in the loading system.

Data line L of computer D also connects:

1. The signal output terminals of the temperature sensors monitoring the environmental parameters in the main testing machine A and auxiliary testing machine B;

2. The signal output terminals of the displacement/deformation sensors for monitoring the displacement/deformation of concrete specimens in main testing machine A and auxiliary testing machine B;

3. The signal output terminal of the stress sensor monitoring the stress of the test piece in the main testing machine A.

The main functions of computer D are:

1. Set the parameters of the real environment to be simulated and the changing rules of each parameter through the computer D, and control the actions of each execution unit that simulates the real environment accordingly, and also accept the environmental parameters fed back by the sensors that monitor the environmental parameters and based on this Control the operation of the actuator through the control unit;

2. Set various test parameters in the test through the computer D, for example: the monitoring time interval of the displacement/deformation sensor and the stress sensor;

3. Setting the relationship between the control unit instructing the action of the power plant and the displacement/deformation sensor and the stress sensor;

4. Output various test results in each test through the data processing system and data output system in the computer D.

A computer control system, including a data acquisition system and a data processing and output system comprising at least temperature, displacement/deformation and stress composed of the aforementioned sensors; the signal output terminals of each of the sensors and the data processing of the computer control system The system is connected to the corresponding signal input end of the data output system, and the signal output end of the data processing system and the data output system is connected to the signal input end of an actuator, which includes the power device in the loading system and the air conditioning device The heating and/or cooling device, to adjust the environment of the environmental chamber and/or the concrete specimen holding space consistent with the set real environment and/or start or stop the power device; the data processing system and data output system Connecting to calculate and output at least one result of the concrete specimen in the simulated real environment, including constraint stress, free variable, elastic modulus, deformation separation, and creep.

Through the computer D and the control system D1 and the actuators set in the main testing machine A and the auxiliary testing machine B to simulate the real environment, a set real environment is simulated on the test piece and in the environment where the test piece is located. In the environment, the deformation of the specimen in different temperatures and other environments is obtained through the computer D and the control system D1 through the displacement/deformation sensor, and then the loading system set and controlled by the computer D and the control system D1 is applied to the specimen in the main testing machine A. Tension or pressure, complete the whole process of tests such as free restraint, restraint stress, elastic modulus, deformation separation, concrete creep and concrete cracking, and obtain various performance parameters of concrete in various simulated environments, auxiliary testing machine B The same test block in is in a free and unconstrained state, and the deformation of the test block can be used as a comparison.

The test device and test method provided by the present invention are described in detail below.

Fig. 2 shows a kind of main testing machine, and it comprises base 1, and environment box 2 is set on base 1, is also provided with a frame 4 on base 1, is also provided with test piece accommodating fixture 3 in environment box 2 ( See Figure 3, Figure 5).

As shown in Figure 3, the environmental box 2 includes a box body 21 with an open upper end and a box cover 22 for closing the open upper end, so as to form a closed space separated from the surrounding environment, in order to pass the real environment simulation The system builds the real environment required for the test.

The environment box 2 isolates the internal heat from being transmitted to the reaction frame 4 and the base 1, and also isolates the external heat from being transmitted to the inside, which ensures the ease of temperature control and avoids the thermal expansion and contraction of the equipment base 1. influence on the measurement results.

As shown in Figures 3 and 5, the test piece accommodating and fixing device 3 is arranged in the environmental chamber 2, and includes a fixed chuck 311, a movable chuck 312, and a fixed side template 313 in the middle of the test piece, and the three are combined to form a A concrete specimen accommodating space 31 with an open upper end or an open upper and lower end. The cross-sectional shape of the accommodating space 31 is: the two ends are a head with a larger width and a shorter length, and the middle is a head with a smaller width and a shorter length. The long middle section, the head and the middle section are connected and transitioned by a cone section; the joint between the fixed chuck 311 and the movable chuck 312 and the fixed side template 313 in the middle of the test piece is located at the end of the accommodating space 31 In the range of the middle section, there is a lateral gap a1 between the side of the side template 313 and the movable chuck 312, and an end gap a2 between the end surface of the side template 31 and the movable chuck 312 (as shown in FIG. 6 ). The shape of the concrete test piece accommodating space 31 is basically equal to the shape of the test piece C.

The structure of a test piece holding and fixing device 3 is as follows: the fixed chuck 311 is fixedly arranged on the base 1, and the movable chuck 312 can move relative to the base 1 along the axis of the length direction of the concrete test piece accommodating space. It is arranged on the base 1; the specimen accommodating and fixing device 3 also includes an upper template 314, which closes the upper opening of the concrete specimen accommodating space 31. For the example of the specimen accommodating and fixing device whose upper and lower ends are open, a bottom plate, ie a lower template (not shown in the figure), is provided on the lower bottom surface of the accommodating space 31 . The upper and lower templates and the two side templates are 304 stainless steel templates with a thickness of 70mm, a total of 4 pieces.

In use, concrete can be poured directly onto the bottom plate in the concrete test piece accommodating space 31 to form the test piece C, or the made test piece C that matches the shape of the test piece accommodating space can be placed in the container Set on the bottom plate in the space 31. A support seat 31-1 (see Fig. 5) is provided under the base plate.

As shown in Figures 5 and 6, in order to ensure the repeated positioning accuracy of the side formwork 313, its installation and fixing method adopts a T-shaped groove guide method, and a side formwork slider 313-1 is fixed on the outer surface of the side formwork 313, and the T-shaped slot fixing block 313-2 is fixed at the corresponding position in the center, and the side mold slider 313-1 is slidably fixed in the T-shaped slot on the T-shaped slot fixing block 313-2, so that the side template 313 can be vertical to the container The lateral movement of the longitudinal axis of the space 31, a screw 313-3 is installed on the side wall of the environmental box, the screw 313-3 is screwed on the side mold slider 313-1, and an adjustment handwheel is fixed on the screw 313-3 313-4. Rotate and adjust the handwheel 313-4, and drive the side template 313 to slide left and right in the environmental chamber 2 along the T-shaped groove through the side mold slider.

As shown in FIG. 6 , the maximum adjustment distance a1 between the side of the side formwork 313 and the movable chuck 312 is 10 mm, and the side formwork 313 can be adjusted to the outside to the maximum distance during demoulding. The gap a2 between the end of the side template 313 and the movable chuck is 5 mm to ensure that the side template 313 does not conflict with the movable chuck 312 when the specimen is compressed. There is no gap between the upper formwork 314 and the lower formwork, that is, the bottom plate and the side formwork 313, to ensure that the cement does not squeeze out when the test piece C is made, and the gap a2 between the end of the side formwork 313 and the movable chuck is used when making the test piece C. A very thin copper sheet can be used for padding.

As shown in Figure 3, it also includes a demoulding device, a lifting device is connected to the lower bottom surface of the bottom plate, and the lifting device is connected to a ejection reduction motor 32, and the bottom plate can be pushed out of the accommodation space through the ejection reduction motor 32 31 and take out the concrete specimen C conveniently.

Specifically, the demoulding adopts the automatic ejector device of the screw rod, which is installed at both ends of the bottom of the test piece. The ejection reduction motor 32 drives the sprocket chain to the screw nut, and the nut rotates the screw rod up and down to drive the ejector rod up and down. The test piece C is ejected, and the maximum ejection distance is 150mm. A dust-proof seal is installed at the place of the ejector rod and the bottom template, that is, the bottom plate, to prevent dust and sundries from falling into the gap. The hole of the ejector rod at the bottom plate or the lower formwork adopts the welding form of stainless steel pipe and the bottom form to ensure that the liquid will not leak. Before the test piece is ejected, it is necessary to rotate the side formwork adjustment handwheel 313-4 to remove some gaps from the side formwork 313.

The shape of the test piece accommodating space 31 makes the shape of the test piece at the chuck part in the shape of a bone, with a large fillet transition to ensure that the test piece breaks within the effective length.

The frame 4 arranged on the base 1, as shown in Fig. 2, Fig. 3, Fig. 4 and Fig. 5, the frame 4 includes two columns 41, a fixed beam 42 and a micro-moving beam 43, forming a rectangular frame, The upright column 41 is parallel to the longitudinal direction of the accommodation space, that is, the axial direction of the concrete specimen, and the two beams are respectively fixed at the two ends of the two upright columns. The fixed beam 42 is fixed on the base 1, and the micro-moving beam is arranged on the base, but there is no fixed structure between the base and the base.

The material and cross-sectional size of the column 41 are: to ensure that its stiffness is 5-20 times the maximum strength stress of the concrete without deformation, or the stiffness K is greater than or equal to 2MN/mm; in addition, the material and cross-sectional size of the column also ensure that Its temperature stability is that its temperature difference deformation is less than 10 microns when the temperature is -20-80°C.

A linear motion mechanism is arranged on the micro-movement beam 43. Specifically, as shown in FIGS. 442 is fixed on the restraining shaft 443 through the floating beam 43, and the restraining shaft 443 is connected to the end surface of the movable chuck 312 through the side wall of the environmental box 2, so that the movable chuck 312 is fixed in position or moves in the axial direction; The screw rod 444 screwed with the nut 441 is rotatably fixed on the micro-movement beam 43 .

A displacement/deformation sensor 443-3 is set between the constraint shaft 443 and the environmental box 2, specifically, a measurement top plate 443-1 is set on the constraint shaft 443, and a support base 443-2 is set on the outer wall of the environmental box 2, in which A displacement/deformation sensor 443-3 is arranged on the support base 443-2, and the sensing part of the displacement/deformation sensor 443-3 abuts against the measuring top plate 443-1. A stress sensor 441 - 1 is connected to the nut 441 , and the sensing component on it abuts against the supporting base or the constraining shaft 443 to sense the stress.

The arrangement of the displacement/deformation sensor 443-3 prevents the detection accuracy from being affected by the loading of the power device on the test piece. This is because the micro-movement beam 43 in the frame 4 is not fixedly connected to the base 1, the reaction force of the tension and compression test piece of the power unit will not be transmitted to the base 1, and the displacement/deformation sensor 443-3 is fixed on the environmental box. It is on base 1, so it will not be affected.

As shown in Figure 4 and Figure 7, the displacement/deformation sensors 443-3 are installed at both ends of the test piece in a symmetrical arrangement, each with an accuracy of ±1 μm in two channels, and the same is true in the auxiliary test machine B. The range of the displacement/deformation sensor of the main testing machine: ±100μm, the range of the displacement/deformation sensor of the auxiliary testing machine: ±2000μm.

The support base 443-2 is installed on the base 1, and when the ambient temperature of the laboratory remains constant, the relative position between the measuring end of the displacement/deformation sensor and the fixed end of the specimen will not change, and there is no error in theory.

Specific to a specific embodiment, the constraining shaft 443, movable chuck 312, and fixed chuck 311 are all made of high-rigidity Invar steel, and the coefficient of linear expansion of this material is only (-20-100°C) 1.4x10 ^{- 6} /°C, the impact on the whole device is only 0.000924mm/°C, this error can be deducted from the experimental results, and the results are more accurate; the high-precision slide rail device is used between the bottom of the movable chuck 312 and the base 1 to ensure the test accuracy .

A loading system, including a power device, the power device is arranged on the frame 4 , specifically, the power device is arranged on the micro-movement beam 43 as shown in FIG. 4 and FIG. 5 . The power unit includes a helical gear-worm gear, a speed reducer 445 with a reduction ratio of 650, and a servo motor 446 connected to the speed reducer. The power unit is controlled by a computer-connected loading control unit to make it start and stop and limit its steering . The loading control unit controls parameters such as the start and stop of the servo motor 446 according to the signals sent by the set displacement/deformation sensor and the stress sensor, and according to the requirements of the specific test.

The pitch of the screw rod 444 screwed with the nut 441 is 12mm. Such a linear motion mechanism has a single pulse displacement of only 0.007μm, and the servo motor has closed-loop feedback, which greatly improves the loading and unloading accuracy, and can easily handle it even if the threshold is set at 1μm.

The power device is preferably a servo motor, which is connected to a transmission mechanism of a worm gear reducer. Such a power device greatly improves control precision, feedback speed and efficiency.

Because this test device is used for long-term creep test (loading force is constant), the drive mode of full servo motor hard tooth surface worm gear reducer is used, which greatly improves the accuracy of loading stress control compared with stepping motor. During the experiment, the deformation of the concrete is very small, the servo motor 446 is used in conjunction with the reducer 445, and the speed of the servo motor 446 is steplessly adjustable, and the loading step can be selected arbitrarily, so the displacement control accuracy is higher than that of the stepping motor; the transmission mode The ball screw has higher precision than ordinary screw, and the transmission efficiency is much higher (95%). The transmission adopts rolling friction and has a long service life.

The frame 4 is made of 45 steel, and it is designed as a connection structure of a micro-moving beam with one end fixed and the other floating. Its deformation will not interfere with displacement measurement and will not introduce measurement errors when stressed.

When loading, because the reaction force frame, that is, the floating end of the frame, that is, the micro-movement crossbeam moves, while the fixed end, that is, the fixed crossbeam and the fixed reference end of the specimen do not move, and the displacement/deformation sensor measures the relative position of the top plate and the fixed end of the specimen, so No measurement error will be introduced.

The frame structure adopts the column and beam type, with a weight of about 4 tons, which can meet the long-term creep test requirements and the stiffness requirements of the testing machine itself (stiffness K≥2MN/mm).

Specifically, when the loading frame bears a load of 200KN, the maximum stress point is about 60MPa, which is much smaller than the yield strength and tensile strength of the material. When the loading frame bears a load of 200KN, the fixed beam and the micro-moving beam in the frame bend outward, and the columns on both sides elongate and bend inward due to the bending moment. The total axial deformation is 0.04655+0.04670=0.09325mm, and the stiffness is 200000/0.09325 = 2144772 N/mm = 2.14 MN/mm. When the loaded frame bears a load of 200KN, the minimum safety factor of the frame is 6.49.

The frame provided by the present invention adopts the column and beam type, and has a stable structure. In addition, the columns therein have sufficient rigidity and temperature difference deformation stability, which can well ensure the accuracy of the test.

The fixed chuck 311, the movable chuck 312 and the restraining shaft 443 at both ends are all made of Invar steel 4J36. The diameter of the restraining shaft 443 is 150 mm. Invar steel has a large elastic modulus and a small linear expansion coefficient. The average linear expansion coefficient within the range is only 1.4x10^-6/°C, and the length of the part that affects the measurement is 660mm, so the effect on the experimental result is 0.000924mm/°C, and it is basically unchanged at -80-100°C. The influence on the experimental results can be calculated or measured, and the measurement results are more accurate.

A window is provided on the lid of the environmental chamber to visualize the test process.

Fig. 11 shows the control principle diagram of the whole process test of concrete cracking based on the real environment in one embodiment of the test device provided by the present invention.

As shown in Figure 11, the test device provided by the present invention also includes a computer D and a control system D1, and the control system D1 includes: the control unit for controlling the actions of various actuators in the real environment simulation system in the main test machine A and the auxiliary test machine B and, the control unit in the main testing machine A that controls the action of the actuator for loading the concrete specimen is the control unit of the power device in the loading system.

The computer D is connected to the control system D1 through the data line L, and at the same time, the computer D is also connected to the signal output end of the temperature sensor for monitoring environmental parameters and the signal output of the displacement/deformation sensor for monitoring the displacement/deformation of the concrete specimen through the data line L connected to the signal output terminal of the stress sensor for monitoring the stress of the test piece;

The control signal output terminals of the control system D1 are connected to the control terminals of the actuators.

The control units of the actuators include: a temperature control unit, a displacement/deformation control unit and a loading control unit. The computer D gives instructions, and the control system D1 controls the actions of each actuator, namely: heating or cooling, and the action of the loading mechanism to set Directional loading or unloading allows the specimen C to deform freely or controllably, while the start, direction and stop of the action of the actuator are controlled by the instructions issued by the computer D to the loading control system after receiving the signal from the displacement/deformation sensor. The data processing system in the computer D performs data processing on the information obtained from each sensor according to the specific test, calculates the test structure and/or draws the output of the parameter curve.

The heating or cooling device in the environmental chamber 2 controlled by the temperature control unit and in the sample holding and fixing device 3 can be that a space is set inside the fixed chuck 311, the movable chuck 312 and the side template 313 that form the holding and fixing device. The cavity is connected with the outside world through the cavity, and the heating medium or cooling medium is passed into the cavity. Taking a side template 313 as an example, as shown in Figure 8, a diversion grid is set in the inner cavity of the side template 313 to form a tortuous flow channel, and the inner diversion grid also acts as a reinforcing rib to ensure long-term No deformation after loading and unloading test. The upper template 314 also has such a structure. As shown in FIG. 3 , the cavity is provided with a medium inlet 313-5 at one end, and a medium outlet 313-6 at the other end. The medium inlet and outlet are connected to the medium heating or cooling device, as shown in Fig. 9 and Fig. 10 . The connecting pipe 313-5 on the medium inlet of the side template 313 is connected to the outlet of a pump 313-7, and the inlet connecting pipe of the pump 313-7 is connected to the outlet of a constant temperature box 313-8, wherein a cooling pipe 313-9 is arranged to connect to the cooling device. The compressor refrigerant in the refrigeration unit adopts R502, which is non-toxic and harmless, and has no pollution to the environment. In the incubator 313-8, the heating and cooling medium is 40% ethylene glycol aqueous solution, and the freezing point temperature is -25°C. The inlet of the incubator 313-8 is connected to the medium outlet of the side template 313 to take over. A heating coil 313-10 is provided on the inlet pipe of the pump 313-7.

The heating/cooling device shown in Figure 9, according to the test needs, transports heating medium or cooling medium to the cavities at the side formwork, upper formwork, fixed chuck, movable chuck and even the wall of the environmental chamber 2, etc. The pump 313-7 in the heating or cooling device, the refrigeration device connected to the refrigeration pipe 313-9 and the heating coil 313-10 are actuators, which are controlled by the temperature parameters set in the computer D. In order to simplify the structure of the computer, the temperature control unit can also be completely or partially separated from the computer D, and its flow chart can be changed from FIG. 11 to FIG. 12 .

The heating system of the heating coil 313-10 is shown in Figure 10. The heating pipe, that is, the inlet pipe 313-12 on the pump 313-7 is connected to a temperature sensor a, and the signal output end of the temperature sensor a is connected to the signal of the temperature controller b. Input and output terminals, the temperature data transmission end of the temperature controller b is connected to the corresponding signal IO terminal of the heating controller c, and according to the temperature data transmitted by the temperature controller b, the heating controller c outputs a suitable voltage to the heating coil 313-10 , current, so that the heating coil 313-10 generates heat, which reflects the set temperature to the outside, and provides a simulation of the set real environment.

If a low temperature is to be provided, the heating device stops working, the cooling device starts, the refrigerant circulates in the refrigeration pipe 313-9, and the medium d ethylene glycol aqueous solution in the cooling thermostat is operated, and the pump 313-7 works to feed the fixed chuck and movable chuck The cooling medium can be transported into the cavity of the side template and the cavity of the side template, and can also be transported to the heat exchanger set in the environmental box at the same time. The pump 313-7 acts as an actuator, its start and stop and speed are controlled by the temperature control unit to provide the required temperature.

In order to measure the temperature of the test piece, a temperature sensor can be inserted in the test piece, and generally the temperature sensor for monitoring the test piece is inserted at the axis of the test piece. For this reason, there can be one template temperature measuring hole on each template such as the side template 313 and the fixed chuck and movable chuck. In the embodiment shown in FIG. 1 , a temperature measuring hole 313-11 is set on the side template. The upper template 314-1 is also arranged with three test piece temperature measuring holes 314-2, which are used to insert the temperature sensor into the inside or surface of the test piece C. The temperature sensors are distributed at 1/4, 1/2 and 3/2 of the length of the test piece. 4 places.

An upper template handle 314-2 is arranged on the upper template.

The upper template is placed flat on the top of the test piece, and can be disassembled and installed freely. The medium inlet 313-5 and medium outlet 313-6 at the connection of the circulating fluid are connected by a hose, and the hose does not need to be disassembled during disassembly and installation, ensuring a reliable seal and no leakage .

In order to ensure uniform temperature transfer, the grid structure inside the template restricts the flow form of the liquid inside. The four hollow templates on the top, bottom, left, and right of the test piece are filled with circulating fluid in the same process; PID accurate calculation controls the heating and cooling devices to ensure fine cooling. Thermal compensation, to control the flow rate of circulating fluid input to the template, so that the temperature of the circulating fluid can meet various requirements of the test.

Make the temperature of the environmental chamber meet the various requirements of the test. The shell of the environment box is made of stainless steel, filled with thermal insulation material, tightly sealed without deformation, and the thickness is 150mm.

The thermal insulation environment box wraps the test piece, template, chuck and part of the restraint shaft inside.

In addition to refrigeration units and heating devices, it can also include air humidification devices, namely humidifiers, rainfall devices, namely spray devices, and wind speed devices, namely fan devices. The schematic diagram is shown in Figure 12.

The real environment simulation system also includes solar radiation devices, namely light bulbs.

To simulate the natural environment of the atmosphere, the above-mentioned devices are arranged in the environmental box, for example, a hole is established on the wall of the environmental box 2, and a pipeline is connected, and the pipeline is connected to at least one of the air supply, steam supply, air supply and water spraying devices. . Holes are arranged on the wall of the environmental box, and lamps for simulating solar irradiation are arranged in the holes to form a solar radiation regulating system. Set up a humidity sensor, wind speed sensor, and solar radiation sensor in the environmental chamber.

Correspondingly, in order to simulate the real environment, in addition to the temperature control unit, a humidity control unit is also set to control the opening and closing of the humidifier or the humidification intensity; a rainfall control unit is set to control the opening and closing and flow of the spray device; a wind speed control unit is set Control the opening and closing and rotating speed of the fan, and set the solar radiation device control unit to control the opening and closing and brightness of the light bulb. These control devices can also be set in the auxiliary testing machine B at the same time.

The above-mentioned control units of the actuators can all be included in the control system D1, and its flow charts are shown in Fig. 11 and Fig. 12 .

If you want to increase the simulation of solar radiation, you can open holes in the environmental box and set up light bulbs.

The relationship between each control unit and the computer D is explained as follows by taking solar radiation as an example: the switch of the light bulb is the actuator. Switch, the solar radiation control unit is controlled by the real environmental parameters set in the computer D to perform operations such as closing and opening and intensity adjustment.

Computer D gives instructions to each control unit, or starts or stops each actuator or adjusts its degree according to the comparison results of each parameter of the real environment simulation system set and the data collected by relevant sensors. In this way, various real environments can be simulated in the environmental chamber, so that various tests of the specimen can be carried out in a specific environment.

Computer D can carry out the test functions shown in Figure 13 by collecting information including temperature sensors, displacement/deformation sensors and stress sensors: restraint stress, free variable, elastic modulus, deformation separation and concrete creep, if the test block is By directly pouring concrete into the testing machine, the whole process from solidification to cracking can be tested and evaluated on the concrete.

In the present invention, the main air temperature control system in the simulated real environment system may have two parts, one part is set on the environmental box, and the other part is set on the test piece accommodating and fixing device. The setting on the environmental chamber is more to simulate the air temperature in the real environment, while the setting on the specimen holding and fixing device can simulate the temperature in the real environment such as a concrete dam in a short time. There is no such comprehensive air temperature control system in the test device in the prior art.

In the present invention, concrete can be poured directly in the concrete specimen accommodation space of the specimen accommodation and fixing device, so that the expansion of concrete in the whole process from dilute state to solidification to hardening can be tested in the simulated real environment Changes in deformation and stress, such tests can be used to test the stress and strain of the dam from pouring, solidification to hardening under different environmental conditions, obtain comprehensive data, and provide valuable information for the design and construction of the dam information. The testing device in the prior art has not thought of and can't do the test of this whole process. Of course, the specimen accommodating and fixing device in the test device provided by the present invention can also test the concrete specimens that have been manufactured.

As shown in Figure 1, the auxiliary testing machine F in the testing device provided by the present invention comprises an environment box, namely comprises a specimen accommodating chamber for placing the same specimen as the specimen tested in the main testing machine , as an embodiment, the temperature adjustment device is set in the specimen accommodating cavity, and a humidity adjustment device, a solar radiation adjustment device, a rainfall adjustment device and a wind speed adjustment device are also set; a temperature sensor is set in the test piece accommodating cavity, A humidity sensor, a solar radiation sensor, a rainfall sensor and a wind speed sensor are also provided, each of the sensors is connected to the computer, and the control system D1 is connected to the adjustment device to adjust the environmental parameters in the test piece accommodating chamber and the main The test environment chamber is the same; a displacement/deformation sensor is also arranged in the specimen accommodating cavity to sense the deformation of the specimen.

The environmental parameters in the auxiliary test box are the same as those of the main test box, where a bottom surface for placing the test piece is set, so that the test piece can be deformed freely, and a real environment simulation system is provided in it, and the simulation system includes at least one air conditioning system, which is set A heating or cooling device in the environmental chamber and/or on the test piece; also includes a temperature sensor and a displacement/deformation sensor, the temperature sensor is arranged on the test piece and/or in the environmental chamber; the displacement/ The deformation sensor is arranged on the test piece, which is the same as the main test box; the signal output terminals of each sensor are associated with the computer.

Auxiliary testing machine and under the condition that the friction coefficient between the test piece and the bottom plate of the machine is small enough, measure the free deformation of the auxiliary test piece under the same temperature condition as the main testing machine, and parallel the testing machine under the same temperature condition to make the test data complete.

The test device provided by the present invention, the concrete cracking whole process test device and method based on the real environment are realized in the following ways:

(1) After the completion of the concrete test specimen and the preparation of the corresponding equipment, start the computer control system, that is, the computer, and set the relevant parameters; start the real environment simulation system, and fill in the monthly average temperature, water temperature, cloud amount, and sunny day of the project location Parameters such as solar radiation heat, cloud cover, latitude and concrete surface heat release coefficient, start the simulation of relevant environmental factors according to the test needs, ambient temperature/humidity/rainfall/wind speed/solar radiation;

(2) According to the temperature, displacement and deformation of the concrete measured by each sensor, the computer can obtain the concrete free variables under the simulated conditions of the real environment. The specific operation of measuring the free deformation can be: the specimen is fixed between the fixed chuck and the movable chuck During the period, due to temperature changes, when the specimen expands or contracts, the set stress sensor will display the stress value, and the control system will start the power device to make the linear motion mechanism move in the same direction as the deformation direction until the stress sensor displays the stress value. is zero, the free deformation at this time is obtained from the displacement/deformation sensor, and the measured free variable is prepared for the separation of multiple deformations of concrete (temperature deformation, autogenous volume deformation and creep, etc.);

(3) Control the free deformation of the movable end of the specimen through the computer, control system such as temperature control unit, displacement/deformation control unit, loading control unit and corresponding sensors. According to the free deformation and the reduced deformation of the control, it can be measured The temperature stress of concrete under different constraints at each moment under the real environment simulation conditions, including the stress when the displacement is reduced to zero, that is, the temperature stress under full constraint conditions;

(4) Through computer, control system such as temperature control unit, displacement/deformation control unit, loading control unit and corresponding sensors, the free deformation of the movable end of the specimen is controlled once, and the displacement/deformation is performed at regular intervals. Once changed, the corresponding stress change is collected at the same time to obtain the elastic modulus at that moment, and so repeated, the elastic modulus of the concrete in the entire development process under the real environment simulation conditions can be obtained;

(5) According to the concrete thermal expansion coefficient α and the temperature change ΔT(t) obtained by the data acquisition system, the pure temperature deformation of concrete under the simulated conditions of the real environment can be obtained, combined with the measured free deformation, other deformations can be obtained, mainly Including autogenous volume deformation and drying shrinkage deformation;

(6) According to the measured concrete elastic modulus and free deformation, the concrete stress can be calculated under the simulated conditions of the real environment without being affected by creep, and the computer control system, displacement/deformation control unit, loading control unit and corresponding sensors can be started , to control the deformation of the concrete so that the deformation is zero, and the difference between the measured stress and the stress when not affected by creep is the stress caused by creep under the simulated conditions of the real environment;

(7) Start the data processing system and combine all the test data and data curves. When there is a sudden change in the stress and displacement curves, it means that the concrete is cracked. The relevant temperature, stress, displacement and deformation parameters of the concrete at this moment can be used as the real ambient temperature. Cracking index under certain conditions provides test reference for the evaluation of concrete crack resistance.

The specific operation of the free constraint is: the test device clamps the two ends of the concrete specimen, one end is fixed, and the other end can control the movement. Under the real environment simulation conditions, the controllable end of the concrete is not loaded, and the time interval ( The computer control system, displacement/deformation control system and loading system of t) make its free displacement μ(t), which is the free variable ε(t) of concrete at time t.

The specific operation of the constrained stress is: the test device clamps both ends of the concrete specimen, one end is fixed, and the other end can control the movement. Under the real environment simulation conditions, the free displacement of the movable end of the concrete specimen is μ(t), according to According to actual needs, the displacement of the movable end of the test piece is reduced through the computer control system, the displacement/deformation control unit and the loading system. At this time, the stress sensor measures different degrees of constraint at each moment, which is the condition of the constraint coefficient f(t) Concrete temperature stress σ(t) under ;

The reduced displacement of the movable end is:

f(t)×μ(t)(6)

In the formula, t is time, f(t) is the concrete constraint coefficient at time t, and μ(t) is the free displacement of the movable end of the concrete specimen.

The specific operation of the elastic modulus is as follows: specifically, set a time interval in the computer control system, and make a displacement change to the movable end of the test piece through the displacement control system at every time interval, and measure the displacement change according to the stress sensor to cause The stress change of the specimen was tested for elastic modulus.

Every △t time, the displacement/deformation control system makes a displacement change Δμ(t) on the test piece and the loading system on the movable end, and the deformation Δε(t) is obtained, and the stress change measured by the stress sensor is Δσ (t), then the elastic modulus of concrete at time t is:

$\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; \&sigma;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; \&epsiv;</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

According to the designed time interval, the computer control system automatically measures the elastic modulus of concrete at different times, and the elastic modulus of the concrete in the entire development process can be obtained.

The specific operation of the separation of the deformation is as follows: firstly, free constraint: the test device fixes one end of the concrete specimen, and the other end can be freely expanded and contracted, and the real environment provided by the real environment simulation system is used to perform a free variable test on the specimen. In the set time zone (t), the deformation amount ε(t) is collected for a set period of time.

After the age of 1 day, the thermal expansion coefficient of concrete will basically not change, and it is generally considered to be a constant. This parameter can also be measured by a special thermal expansion coefficient tester, which is considered to be a constant α here. According to the concrete thermal expansion coefficient α and the temperature change ΔT(t) measured by the temperature control system, the temperature deformation of concrete under the real environment simulation conditions can be obtained:

ΔεT(t)＝α· _ΔT (t)(8)

Combined with the measured free deformation ε(t) and separated, other deformations Δε _a (t) can be obtained, mainly including autogenous volume deformation and drying shrinkage deformation:

Δε _a (t) = ε (t) - Δε _T (t) (9)

The specific operation of the concrete creep is as follows: according to the measured concrete elastic modulus E(t) and free deformation ε(t), the concrete stress σ(t) when not affected by creep under the real environment simulation conditions can be calculated:

σ(t)=ε(t)·E(t)(10)

Start the concrete displacement control system to control the deformation of the concrete so that the deformation is zero. At this time, the measured stress is σ ₀ (t), and the stress reduction caused by creep under the real environment simulation conditions is:

σ _c (t) = σ (t) - σ ₀ (t) (11)

The degree of influence of concrete creep can be obtained by the size of σ _c (t), where t is time.

The specific operation of the whole process of concrete cracking is: the concrete temperature changes from the initial temperature to the set temperature, the two ends of the specimen are fixed, or the tensile force is applied, when the tensile stress data suddenly decreases, the displacement suddenly increases, and the corresponding time-stress , When a sudden change occurs on the time-deformation/displacement curve, the concrete cracks, and the relevant parameters of the concrete at this time are obtained, including temperature, tensile strength, and ultimate tensile value.

The specific operation of the evaluation is: combined with the previous test data and results of A, B, C, D, and E, when the concrete temperature changes to the set level, when the tensile stress data suddenly decreases, the displacement suddenly increases, and there is a sudden change on the corresponding curve , concrete cracking, at this time, the relevant parameters of concrete temperature, stress, displacement and deformation can be used as the whole process evaluation of concrete cracking for this specimen.

For the real environment, it can be set as follows:

①Ambient temperature

It depends on the local conditions, that is, to simulate the real environment, and fit the average temperature data of the previous month into a cosine curve. The following formula (1) is the calculation formula after fitting:

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; m</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; \&lsqb;</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 6</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&tau;</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

In the formula, T _a is the temperature, T _am is the annual average temperature, A _a is the annual temperature variation, τ is the time (month), and τ ₀ is the time (month) when the temperature is the highest.

Considering the diurnal variation of temperature, the following formula is used for calculation:

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; A</span>}\mathrm{<span\; class="notranslate">\; c</span>}\mathrm{<span\; class="notranslate">\; o</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}<span\; class="notranslate">\; \&lsqb;</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}}{\mathrm{<span\; class="notranslate">\; 12</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 14</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&rsqb;</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In the formula, is the daily temperature, T _a is the monthly average temperature, A is the daily variation range of the temperature, and t is the time (hour) in a day, which depends on different seasons in different regions.

② Solar radiation heat

Concrete buildings are often exposed to solar radiation, which has a significant effect on the concrete temperature. The heat radiated by the sun on a unit area per unit time is S, where the part absorbed by the concrete is R, and the rest is reflected, then:

R＝α _s S(3)

In the formula, α _s is the absorption coefficient, also known as the blackness coefficient, and the concrete surface is generally taken as 0.65.

S=S ₀ (1-kn)(4)

In the formula, S ₀ is the solar radiant heat in sunny days, n is the cloud amount, and k is the coefficient, and these three values are given by the local meteorological station;

The impact of sunshine is equivalent to the increase of the temperature of the surrounding air by ΔT _a ,

ΔT _a =R/β(5)

In the formula, β is the heat dissipation coefficient of the concrete surface, which is calculated according to the surface roughness and wind speed.

③Rainfall

Query the rainfall of the meteorological department where the project is located, and simulate rainfall through rainfall equipment and rainfall controllers.

④ wind speed

Query the wind speed of the meteorological department where the project is located, and start the wind speed simulation device to obtain the heat dissipation coefficient of the concrete surface according to the wind speed.

A specific test example is as follows:

The above-mentioned test method and test device were used to test the concrete test block to verify the effectiveness and rationality of the test device and method based on the real environment for the whole process of concrete cracking. The temperature of the test environment is the measured value of the temperature of an actual project in the past year, input into the computer, and start the test device, so that the test environment changes completely according to the measured temperature, and the stress change of the concrete test block is tested under this ambient temperature condition , to study the whole process of concrete cracking based on the real environment.

From the test data obtained from the test, it can be seen that the ambient temperature conforms to the actual sinusoidal change law of the project and can truly reflect the actual engineering environment; the test temperature stress based on this ambient temperature condition can reflect the real stress change law, and the Based on the effect of thermal expansion and cold contraction, when the ambient temperature rises, the compressive stress of concrete increases; when the ambient temperature decreases, the compressive stress of concrete decreases and the tensile stress increases, as shown in Figure 14.

Claims (6)

1. A concrete cracking whole process test device based on real environment, is characterized in that: comprise a base, be provided with on this base: An environmental chamber, having at least four walls and a top cover, forming a closed space, separated from the surrounding environment; A concrete specimen accommodation device, which is set in the environmental chamber, including fixed chucks, movable chucks, and fixed side formwork in the middle of the specimen, the three are combined to form a concrete specimen with an open upper end or an open upper and lower end The accommodating space, the fixed chuck is fixedly arranged in the environmental chamber, and the movable chuck can be arranged to move along the axis of the length direction of the concrete specimen accommodating space; A temperature sensor is set in the environmental chamber or the accommodating space between the environmental chamber and the concrete specimen; A real environment simulation system, which at least includes a temperature regulating device, which is a heating and/or cooling device, which is arranged in the environmental box and the concrete specimen holding device to simulate the set real environment in temperature; A loading system, including a frame, a transmission device and a power device, the frame is arranged on the base, the transmission device includes a linear motion mechanism, and the driven part enters the environment through the side wall of the environmental box The box is fixed to the movable chuck so that the movable chuck is fixed in position or moves in the direction of the axis, the active part in the linear motion mechanism is fixed on the frame; the power device is arranged on the frame, connected The active part in the linear motion mechanism; A displacement/deformation sensor is arranged on the movable chuck or a part connected with the movable chuck to sense the deformation of the concrete specimen; a stress sensor is arranged on the linear motion mechanism to sense the load borne by the specimen. 2. The test device according to claim 1, characterized in that: the cross-sectional shape of the accommodating space is as follows: the two ends are heads with a larger width and shorter length, and the middle is a middle head with a smaller width and longer length. Section, the head and the middle section are connected and transitioned by a cone section; the joint between the fixed chuck and the movable chuck and the fixed side template in the middle of the test piece is located in the middle section of the accommodating space; and/ Or, the test piece accommodating and fixing device further includes an upper template, which closes the upper end opening of the concrete test piece accommodating space; and/or, There is a gap at the seam between the side template and the movable clamp and/or the fixed clamp, and the gap includes the gap between the end of the side template and the movable clamp to ensure that the test piece is compressed when the side formwork does not interfere with the movable jaws, and/or includes a gap between the sides of the side formwork and the fixed jaws and movable jaws; and/or, The side templates are arranged in the environmental box so as to be movable laterally. 3. The test device according to claim 1 or 2, characterized in that: the real environment simulation system also includes setting at least one adjustment device in the environmental chamber: humidity adjustment device, solar radiation adjustment device, rainfall adjustment Correspondingly, the device and the wind speed regulating device further include at least one of the following sensors: a humidity sensor, a solar radiation sensor, a rainfall sensor and a wind speed sensor. 4. The test device according to one of claims 1 to 3, characterized in that: the heating and/or cooling device in the air temperature control system arranged in the environmental chamber is: In the box wall or in the closed space, the box wall has a hollow chamber, and/or, at least one of the fixed chuck, the movable chuck and the side formwork in the specimen accommodating and fixing device is provided with a hollow chamber ; Each of the hollow chambers is provided with an inlet and an outlet to communicate with the medium passage of the heating or cooling device, and the actuator is an electric heating coil or a driving heating or cooling device arranged on the medium passage of the heating and/or cooling device. Transfer pump for medium flow, used to provide heating or cooling as required during the test. 5. The test device according to claim 3, characterized in that: holes are provided on the wall of the environmental chamber to connect pipelines, and the pipelines are connected to at least one of air supply, steam supply, air supply and water spraying devices. A kind of, correspondingly constitute a humidity adjustment device, a rainfall adjustment device and a wind speed adjustment device; and/or, a hole is provided on the wall of the environmental box, and a lamp for simulating solar irradiation is arranged in the hole to form a solar radiation adjustment device. 6. The test device according to any one of claims 1 to 5, characterized in that: the frame is a rectangular frame comprising two beams and two columns, and a fixed beam is fixed on one side of the fixed chuck On the base, two of the uprights are fixed in parallel with the fixed beams on both sides of the environmental chamber, and a micro-moving beam is set on the base on the side of the movable chuck, and the uprights connected, the power device is arranged on the micro-moving beam, thereby forming a reaction force frame, the linear motion mechanism passes through the micro-moving beam and is connected with the movable chuck, and the displacement/deformation sensor and the stress sensor the support portion is fixed directly or indirectly to the base; and/or, In the frame formed by the two beams and the two uprights, the material and cross-sectional size of the uprights are such that the stiffness is guaranteed to be 5-20 times the maximum strength stress of the concrete without deformation, or The stiffness K is greater than or equal to 2MN/mm; and/or, the temperature stability is guaranteed to be less than 10 microns when the temperature difference deformation is within the temperature range of the test -20-80°C; and/or, A window is arranged on the lid of the environmental chamber so that the test process is visualized; and/or, The power unit is a servo motor connected to a worm gear reducer; and/or, The linear motion mechanism adopts a screw transmission mechanism; and/or, A lifting mechanism is also set on the base, and a base plate is set in the test piece accommodating and fixing device for placing the test piece or pouring the test piece on it, the base plate is connected with the lifting mechanism, and by running the lifting mechanism, it can Move the specimen into or out of the concrete specimen holding space.