CN109425729B - Multi-machine joint control concrete variable constraint equipment and method - Google Patents
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- 239000010453 quartz Substances 0.000 claims abstract description 12
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 12
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Abstract
A multi-machine joint control concrete variable constraint device and method, the device includes template system, temperature system, collecting system, load measuring system, control system and computer system; the template system comprises a free template and a plurality of constraint templates, wherein two quartz rods penetrate through the upper template, and a displacement sensor is arranged between the two quartz rods; the temperature system comprises a water tank, and a temperature control device and a second temperature sensor are arranged in the water tank; the load measuring system comprises a plurality of driving devices corresponding to the constraint templates, the driving devices are connected with a transmission shaft, the transmission shaft is fixedly connected with the center of the movable template, and a load sensor is arranged between the pull rod and the transmission shaft; the input end of the acquisition system is connected with the displacement sensor, the first temperature sensor, the second temperature sensor and the load sensor, the output end of the control system is connected with the driving device, the temperature control device and the water pump, and the acquisition system and the control system are both connected with the computer system.
Description
Technical Field
The invention belongs to the technical field of water conservancy and hydropower, and particularly relates to multi-machine joint control concrete variable constraint equipment and a method.
Background
During the hardening process of concrete, cement hydrates to generate a large amount of hydration heat, which causes the concrete structure to generate a huge temperature deformation. If these volumetric deformations are not limited, no stresses are generated inside the concrete. It is a practical situation that cast-in-place concrete is often restrained by the foundation, adjacent concrete structures or members from free deformation.
When a structure is deformed, there is a possibility of interaction between structures and between components inside the structure, resulting in "constraint".
Constraints can be divided into external constraints and internal constraints according to the constraint action mode. For example, the newly cast concrete member is externally constrained by the surrounding members or the foundation, and the constraint caused by the difference in deformation between points inside the concrete member due to the temperature and humidity variation is referred to as internal constraint.
Constraints can be classified into unconstrained, partially constrained, and fully constrained according to the degree of constraint. The unconstrained concrete member can deform freely without being limited by external conditions, and the stress is not generated inside the concrete member; partial constraint means that the concrete member cannot be freely deformed, and partial deformation is constrained; by fully constrained is meant that the concrete cannot deform, i.e. all deformation is limited.
Generally speaking, the larger the degree of constraint, the greater the stress of the concrete, and the more likely the concrete cracks occur.
At present, concrete constraint degree tests in a test room mostly adopt complete constraint conditions, and the conditions are easy to realize in software. However, in practical engineering, the concrete structure is often in a variable constraint state, and the experimental results obtained in a laboratory are harsh, so that the concrete structure is directly used in engineering, and a large amount of raw materials can be consumed, so that the concrete structure is uneconomical.
Disclosure of Invention
The invention aims to provide multi-machine joint control concrete variable constraint equipment and a multi-machine joint control concrete variable constraint method, which can accurately evaluate the concrete cracking risk under different constraint degree conditions and provide a parameter foundation for temperature control optimization design of a large-volume concrete structure.
In order to achieve the purpose, the invention adopts the following technical scheme:
a multi-machine joint control concrete variable constraint device comprises a template system, a temperature system, a collecting system, a load measuring system, a control system and a computer system;
the template system comprises a free template and a plurality of constrained templates, wherein the free template and the constrained templates respectively comprise an upper template with a temperature control channel, a lower template and two symmetrical side templates to form a cylinder with a rectangular cross section; end templates with temperature control channels are respectively arranged at two ends of the side template of the free template, and a sealed free pouring space is enclosed among the upper template, the lower template, the side template and the end templates of the free template; a fixed template and a movable template are respectively arranged at two ends of the side template of each constraint template, and a sealed constraint pouring space is formed by enclosing the upper template, the lower template, the side templates, the fixed template and the movable template of each constraint template; two quartz rods penetrate through each upper template, and a displacement sensor is arranged between the two quartz rods; the centers of the upper template, the lower template, the side templates, the end templates, the fixed template, the movable template, the free pouring space and the constraint pouring space are all provided with a first temperature sensor; the free template is provided with a displacement data server which is connected with a displacement sensor of the free template; each constraint template is provided with a displacement data receiver which is connected with a displacement sensor of the constraint template; the displacement data server is connected with each displacement data receiver in a wired or wireless mode;
the temperature system comprises a water tank with a water pump, the water tank is provided with a water outlet pipe and a water return pipe, the water outlet pipe is respectively connected to the water inlet ends of the temperature control channels of the upper template, the lower template, the side template and the end template, and the water return pipe is respectively connected to the water outlet ends of the temperature control channels of the upper template, the lower template, the side template and the end template; a temperature control device and a second temperature sensor are arranged in the water tank;
the load measuring system comprises a plurality of driving devices corresponding to the constraint templates, and the driving devices are connected with a transmission shaft and can push and pull the transmission shaft; the tail end of the transmission shaft is fixedly connected with the center of the movable template through a pull rod, and a load sensor is arranged between the pull rod and the transmission shaft;
the input end of the acquisition system is connected with the displacement sensor, the first temperature sensor, the second temperature sensor and the load sensor, and the output end of the acquisition system is connected with the input end of the computer system;
the input end of the control system is connected with the output end of the computer system, and the output end of the control system is connected with the driving device, the temperature control device and the water pump.
Furthermore, heat insulation layers are arranged on the outer sides of the upper template, the lower template, the side templates and the end templates.
Furthermore, the upper template is detachable.
Further, the driving device is a motor.
Further, the wireless mode is bluetooth or WIFI.
A multi-machine joint control concrete variable constraint method utilizes the multi-machine joint control concrete variable constraint equipment, and comprises the following steps:
pouring the stirred concrete into the constrained pouring space and the free pouring space respectively to form a constrained concrete test piece and a free concrete test piece respectively; covering the upper template, and enabling a lead of the pre-embedded first temperature sensor to penetrate out of a preformed hole of the upper template and be connected with the acquisition system;
the computer system sets the preset temperature of the concrete test piece, starts a test, enables water in the water tank to reach the preset temperature through the temperature control device, enables the water to circulate in the temperature control channel through the water pump, regulates and controls the temperatures of the upper template, the lower template, the side templates and the end template, and finally enables the temperatures of the restrained concrete test piece and the free concrete test piece to reach the preset temperature T; measuring temperature data through the first temperature sensor and the second temperature sensor;
after the concrete is initially set, measuring deformation data through the displacement sensor;
under the one-dimensional condition, the deformation of the free concrete specimen in the free state is delta lfThe deformation amount delta l of the confined concrete specimen in the confined staterDegree of constraint of concrete gammaRDefined by the ratio of the amount of deformation occurring in the constrained state to the amount of deformation in the free state, i.e.
And (3) realizing variable constraints:
A. displacement sensor for monitoring free template measures shrinkage deformation delta epsilon of free concrete specimen under any temperature historysh；
B. Monitoring the deformation delta epsilon of the confined concrete specimen in delta t time;
if it satisfies
|Δε|＝|(1-γR)Δε sh|+Δεlim (2)
In the formula, Δ εlimIs a set constraint specimen allowable deformation limit value;
applying load to the restrained concrete sample until the deformation of the restrained concrete sample reaches
Δεres＝(1-γR)Δεsh (3)
And repeating the steps A and B to obtain the development process of the concrete constraint stress under the condition of any constraint degree.
Further, the step of realizing multi-machine joint control:
D. displacement sensor for monitoring free template measures shrinkage deformation delta epsilon of free concrete specimen under any temperature historysh；
E. The displacement data server computer for controlling the free concrete test piece transmits the displacement data of the free concrete test piece to displacement data receiver computers for restraining the control of the concrete test piece in a WiFi mode through a TCP/UDP protocol;
F. and the displacement data receiver computer of each constrained concrete test piece imports the data into the computer system according to the received shrinkage deformation of the free concrete test piece, and the computer system drives the driving device through the control system to regulate and control the deformation of each constrained concrete test piece.
Further, the history of the predetermined temperature is calculated as follows:
aiming at the local conditions of the experiment, the monthly average temperature data are fitted into a cosine curve, and the following formula (4) is a calculation formula after fitting:
in the formula, TaIs air temperature, TamIs the average annual temperature, AaThe annual variation of air temperature, tau is time (month), tau0The time (month) when the air temperature is highest;
taking into account the daily change in air temperature, the calculation is performed by using the following formula (5):
in the formula (I), the compound is shown in the specification,
the daily temperature, TaThe average temperature per month, A is the daily variation range of the temperature, and t is the time (time) in 1 day, which is determined according to different seasons in different regions.
The invention has the beneficial effects that: the multi-machine joint control concrete variable constraint equipment and the method can acquire the constraint stress development process of the concrete under the condition of different constraint degrees, solve the defect of single constraint degree of similar test equipment in a conventional laboratory, and improve the richness of the measurement data of the temperature stress tester.
Drawings
FIG. 1 is a schematic structural diagram of the multi-unit joint control concrete variable constraint equipment.
Detailed Description
The following description is given by way of example only, and not by way of limitation, of the scope of the invention.
As shown in figure 1, the invention provides a multi-machine joint control concrete variable constraint device which comprises a template system, a temperature system, a collecting system, a load measuring system, a control system and a computer system.
The template system comprises a free template A and a plurality of constrained templates B, wherein the free template A and the constrained templates B respectively comprise an upper template 1 with a temperature control channel, a lower template 2 and two symmetrical side templates 3, and form a cylinder shape with a rectangular cross section. End templates 4 with temperature control channels are respectively arranged at two ends of the side template 3 of the free template A, and a sealed free pouring space C is formed among the upper template 1, the lower template 2, the side template 3 and the end templates 4 of the free template A in a surrounding manner. And two ends of the side template 3 of each constraint template B are respectively provided with a fixed template 5 and a movable template 6, and a sealed constraint pouring space D is formed among the upper template 1, the lower template 2, the side templates 3, the fixed template 5 and the movable template 6 of the constraint template B in a surrounding manner. This cope match-plate pattern 1 is detachable, and this cope match-plate pattern 1, lower bolster 2, side form 3 and the 4 outsides of tip templates are equipped with the heat preservation. Two quartz rods 7 penetrate through each upper template 1, and a displacement sensor 8 is arranged between the two quartz rods. The displacement control method adopted by the invention comprises the following steps: the displacement sensor 8 is fixed at one end of the quartz rod 7 (the thermal expansion coefficient of the quartz rod is smaller and is about 1 mu m/DEG C), the quartz rod 7 is directly embedded into the pouring space by adopting an embedded part, so that the quartz rod drives the displacement sensor to deform synchronously with the concrete sample, the actual deformation of the concrete sample measured by the displacement sensor 8 is ensured, unnecessary measurement errors are avoided, the limitation of the aggregate particle size of the concrete sample is avoided, and the measurement method is reasonable. The center of the upper template 1, the center of the lower template 2, the center of the side template 3, the center of the end template 4, the center of the fixed template 5, the center of the movable template 6, the center of the free pouring space C and the center of the constrained pouring space D are all provided with first temperature sensors. The free template A is provided with a displacement data server E which is connected with a displacement sensor 8 of the free template A. Each constraint template B is provided with a displacement data receiver F which is connected with a displacement sensor 8 of the constraint template B. The displacement data server E is connected with each displacement data receiver F in a wired or wireless mode, and the wireless mode can be Bluetooth or WIFI.
The temperature system comprises a water tank 9 with a water pump, the water tank is provided with a water outlet pipe and a water return pipe, the water outlet pipe is respectively connected to the water inlet ends of the temperature control channels of the upper template 1, the lower template 2, the side templates 3 and the end templates 4, and the water return pipe is respectively connected to the water outlet ends of the temperature control channels of the upper template 1, the lower template 2, the side templates 3 and the end templates 4. A temperature control device and a second temperature sensor are arranged in the water tank 9. The temperature system of the invention is based on a computer control system, and can carry out temperature closed-loop control on a temperature control device (a heating and refrigerating device) according to a set temperature course: sending liquid into the water tank, utilizing the heating and refrigerating assembly to adjust the liquid to the required temperature, utilizing the pressurizing assembly (water pump) to input the liquid into the temperature control channel, and enabling the temperature of the concrete test piece to develop according to a preset curve. In order to ensure uniform temperature transfer, the same-stroke circulating liquid is arranged in the temperature control channel; PID accurately calculates and controls the heating and refrigerating device, ensures fine cold and hot compensation, and controls the flow of the circulating liquid of the input temperature control channel, so that the temperature of the circulating liquid meets various requirements of tests. The template is internally divided into two layers, a water layer is arranged on the concrete test piece contact layer, a heat insulation layer is arranged on the air contact part, the heat insulation layer can isolate the temperature of the test piece from the temperature in the environment box, the mutual influence is reduced, and the temperature is easy to control.
The load measuring system comprises a plurality of driving devices 10, such as motors, corresponding to the constraint templates B, wherein the driving devices 10 are connected with a transmission shaft 11, and can push and pull the transmission shaft 11. The end of the transmission shaft 11 is fixedly connected with the center of the movable template 6 through a pull rod 12, and a load sensor 13 is arranged between the pull rod 12 and the transmission shaft 11. After the motor receives a control instruction of a computer system, the motor drives the transmission shaft to apply tension/pressure to the end part of the movable template, so that the displacement measurement data can meet the test requirements, and the load sensor directly reflects the stress state of the confined concrete sample.
The input end of the collecting system 14 is connected to the displacement sensor 8, the first temperature sensor, the second temperature sensor and the load sensor 13, and the output end of the collecting system 14 is connected to the input end of the computer system 15.
The input end of the control system 16 is connected to the output end of the computer system 15, and the output end of the control system 16 is connected to the driving device 10, the temperature control device and the water pump.
The invention also provides a multi-machine joint control concrete variable constraint method, which utilizes the multi-machine joint control concrete variable constraint equipment and comprises the following steps:
pouring the stirred concrete into the constrained casting space D and the free casting space C respectively to form a constrained concrete test piece and a free concrete test piece respectively; covering the upper template 1, and enabling a lead of the pre-embedded first temperature sensor to penetrate out of a preformed hole of the upper template 1 and be connected with the acquisition system 14;
the computer system 15 sets the preset temperature of the concrete sample, starts the test, enables the water in the water tank 9 to reach the preset temperature through the temperature control device, enables the water to circulate in the temperature control channel through the water pump, regulates and controls the temperatures of the upper template 1, the lower template 2, the side templates 3 and the end template 4, and finally enables the temperatures of the restrained concrete sample and the free concrete sample to reach the preset temperature T; measuring temperature data through the first temperature sensor and the second temperature sensor;
after the concrete is initially set, measuring deformation data through the displacement sensor 8;
under the one-dimensional condition, the deformation of the free concrete specimen in the free state is delta lfThe deformation amount delta l of the confined concrete specimen in the confined staterDegree of constraint of concrete gammaRDefined by the ratio of the amount of deformation occurring in the constrained state to the amount of deformation in the free state, i.e.
And (3) realizing variable constraints:
C. the displacement sensor 8 for monitoring the free template A measures the shrinkage deformation delta epsilon of the free concrete specimen under any temperature historysh；
D. Monitoring the deformation delta epsilon of the confined concrete specimen in delta t time;
if it satisfies
|Δε|＝|(1-γR)Δεsh|+Δεlim (2)
In the formula, Δ εlimIs a set constraint specimen allowable deformation limit value;
applying load to the restrained concrete sample until the deformation of the restrained concrete sample reaches
Δεres＝(1-γR)Δεsh (3)
And repeating the steps A and B to obtain the development process of the concrete constraint stress under the condition of any constraint degree.
The method comprises the following steps of realizing multi-machine joint control:
D. the displacement sensor 8 for monitoring the free template A measures the shrinkage deformation delta epsilon of the free concrete specimen under any temperature historysh；
E. The displacement data server E computer for controlling the free concrete test piece transmits the displacement data of the free concrete test piece to the displacement data receiver F computer for controlling each restrained concrete test piece in a WiFi mode through a TCP/UDP protocol;
F. the displacement data receiver F computer of each constrained concrete sample imports the data into the computer system 15 according to the received shrinkage deformation of the free concrete sample, and the computer system 15 drives the driving device 10 through the control system 16 to regulate and control the deformation of each constrained concrete sample.
The history of the predetermined temperature is calculated as follows:
aiming at the local conditions of the experiment, the monthly average temperature data are fitted into a cosine curve, and the following formula (4) is a calculation formula after fitting:
in the formula, TaIs air temperature, TamIs the average annual temperature, AaThe annual variation of air temperature, tau is time (month), tau0The time (month) when the air temperature is highest;
taking into account the daily change in air temperature, the calculation is performed by using the following formula (5):
in the formula (I), the compound is shown in the specification,
the daily temperature, TaThe average temperature per month, A is the daily variation range of the temperature, and t is the time (time) in 1 day, which is determined according to different seasons in different regions.
The invention has the following advantages:
1. the invention can simulate the stress development process of concrete under different constraint degrees, improves the application range of the variable constraint degree of simulation engineering in a laboratory, and provides reference for concrete engineering construction and crack prevention.
2. The invention can input different temperature boundaries of concrete according to the concrete temperature control technical requirements of actual engineering, and simulate various concrete curing conditions.
3. The invention can carry out free deformation measurement tests on concrete under different curing conditions.
4. The invention can perform the constraint stress test on the concrete under the condition of different constraint degrees.
5. The invention can control the deformation process of the constrained test piece of a plurality of hosts based on the deformation data of the free test piece, and realize the parallel test of the concrete constrained test with different constrained degrees.
6. The invention can analyze and evaluate the whole cracking process of the concrete according to the development process of the concrete constraint stress obtained by tests under different constraint degrees, and provides reference for the anti-cracking design of the concrete.
The invention is defined by the claims. Based on this, it should be understood that various obvious changes and modifications can be made by those skilled in the art, which are within the main spirit and scope of the present invention.
Claims (1)
1. A multi-machine joint control concrete variable constraint method is characterized by comprising the following steps: the multi-machine joint control concrete variable constraint equipment comprises a template system, a temperature system, an acquisition system, a load measurement system, a control system and a computer system;
the template system comprises a free template and a plurality of constrained templates, wherein the free template and the constrained templates respectively comprise an upper template with a temperature control channel, a lower template and two symmetrical side templates to form a cylinder with a rectangular cross section; end templates with temperature control channels are respectively arranged at two ends of the side template of the free template, and a sealed free pouring space is enclosed among the upper template, the lower template, the side template and the end templates of the free template; a fixed template and a movable template are respectively arranged at two ends of the side template of each constraint template, and a sealed constraint pouring space is formed by enclosing the upper template, the lower template, the side templates, the fixed template and the movable template of each constraint template; two quartz rods penetrate through each upper template, and a displacement sensor is arranged between the two quartz rods; the centers of the upper template, the lower template, the side templates, the end templates, the fixed template, the movable template, the free pouring space and the constraint pouring space are all provided with a first temperature sensor; the free template is provided with a displacement data server which is connected with a displacement sensor of the free template; each constraint template is provided with a displacement data receiver which is connected with a displacement sensor of the constraint template; the displacement data server is connected with each displacement data receiver in a wired or wireless mode; the free pouring space and the constraint pouring space are both in a cylindrical shape with a rectangular section;
the temperature system comprises a water tank with a water pump, the water tank is provided with a water outlet pipe and a water return pipe, the water outlet pipe is respectively connected to the water inlet ends of the temperature control channels of the upper template, the lower template, the side template and the end template, and the water return pipe is respectively connected to the water outlet ends of the temperature control channels of the upper template, the lower template, the side template and the end template; a temperature control device and a second temperature sensor are arranged in the water tank;
the load measuring system comprises a plurality of driving devices corresponding to the constraint templates, wherein each driving device is connected with the corresponding transmission shaft and can push and pull the corresponding transmission shaft; the tail end of each transmission shaft is fixedly connected with the center of the corresponding movable template through a pull rod, and a load sensor is arranged between each pull rod and the corresponding transmission shaft;
the input end of the acquisition system is connected with the displacement sensor, the first temperature sensor, the second temperature sensor and the load sensor, and the output end of the acquisition system is connected with the input end of the computer system;
the input end of the control system is connected with the output end of the computer system, and the output end of the control system is connected with the driving device, the temperature control device and the water pump;
the method for changing and constraining the concrete under multi-machine joint control comprises the following steps:
pouring the stirred concrete into the constrained pouring space and the free pouring space respectively to form a constrained concrete test piece and a free concrete test piece respectively; covering the upper template, and enabling a lead of the pre-embedded first temperature sensor to penetrate out of a preformed hole of the upper template and be connected with the acquisition system;
the computer system sets the preset temperature of the concrete test piece, starts a test, enables water in the water tank to reach the preset temperature through the temperature control device, enables the water to circulate in the temperature control channel through the water pump, regulates and controls the temperatures of the upper template, the lower template, the side templates and the end template, and finally enables the temperatures of the restrained concrete test piece and the free concrete test piece to reach the preset temperature T; measuring temperature data through the first temperature sensor and the second temperature sensor;
after the concrete is initially set, measuring deformation data through the displacement sensor;
under the one-dimensional condition, the deformation of the free concrete specimen in the free state is delta lfThe deformation amount delta l of the confined concrete specimen in the confined staterDegree of constraint of concrete gammaRDefined by the ratio of the amount of deformation occurring in the constrained state to the amount of deformation in the free state, i.e.
And (3) realizing variable constraints:
A. displacement sensor for monitoring free template measures shrinkage deformation delta epsilon of free concrete specimen under any temperature historysh；
B. Monitoring the deformation delta epsilon of the confined concrete specimen in delta t time;
if it satisfies
|Δε|＝|(1-γR)Δεsh|+Δεlim (2)
In the formula, Δ εlimIs a set constraint specimen allowable deformation limit value;
applying load to the restrained concrete sample until the deformation of the restrained concrete sample reaches
Δεres＝(1-γR)Δεsh (3)
Repeating the step A and the step B to obtain the development process of the concrete constraint stress under the condition of any constraint degree;
C. displacement sensor for monitoring free template measures shrinkage deformation delta epsilon of free concrete specimen under any temperature historysh；
D. The displacement data server computer for controlling the free concrete test piece transmits the displacement data of the free concrete test piece to displacement data receiver computers for restraining the control of the concrete test piece in a WiFi mode through a TCP/UDP protocol;
E. and the displacement data receiver computer of each constrained concrete test piece imports the data into the computer system according to the received shrinkage deformation of the free concrete test piece, and the computer system drives the driving device through the control system to regulate and control the deformation of each constrained concrete test piece.
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| CN105424494B (en) * | 2015-09-09 | 2018-01-19 | 中国水利水电科学研究院 | Concrete water flowing cools down overall process experimental rig and method |
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