A large-volume concrete crack resistance testing device

Abstract

This utility model belongs to the field of concrete mechanical property testing technology, specifically relating to a large-volume concrete crack resistance testing device to solve the problems of difficulty in positioning and shaping the temperature-regulating tube in existing technologies, and the inability to precisely fine-tune its position during the shaping process. It includes a temperature-regulating tube, a shaping and limiting mechanism, an inflation mechanism, and a liquid supply mechanism. When inflation is required, the inflation mechanism inflates the shaping valve to expand and shape the temperature-regulating tube. After the temperature-regulating tube has expanded and shaped, the inflation mechanism and the shaping and limiting mechanism are removed. When temperature regulation is required, the liquid supply mechanism's outlet is connected to the first free end, and its return port is connected to the second free end. This device achieves precise positioning and shaping of the temperature-regulating tube, and allows for precise fine-tuning of its position during the inflation and shaping stage.

Description

Technical Field

[0001] This utility model belongs to the field of concrete mechanical property testing technology, and specifically relates to a large-volume concrete crack resistance testing device. Background Technology

[0002] In bridge engineering, the mechanical properties of the concrete in the negative bending moment zone of steel-concrete composite beams directly determine the overall structural safety and long-term durability. Bending-tension testing is the core technical method for evaluating the mechanical properties of concrete in this region.

[0003] Large-volume bridge decks are affected by temperature differences in the natural environment, exhibiting slow-rate temperature changes and non-uniform temperature gradient distribution. The temperature difference between the surface and core areas is significant, and the temperature change process is gradual and continuous. However, existing flexural tensile tests use small-sized specimens, which, due to their small heat capacity and high heat conduction efficiency, easily achieve a uniform temperature state. This makes it impossible to replicate the actual temperature change rate and gradient distribution in the engineering field, resulting in significant deviations between the concrete flexural tensile mechanical test data under the coupled effect of temperature and engineering practice.

[0004] To simulate the internal temperature gradient of concrete, some existing technologies embed temperature-regulating pipes inside the test block and control the temperature by introducing a temperature-regulating liquid. However, the following prominent problems still exist:

[0005] Temperature control tubes are difficult to position and shape inside the test block: Flexible hoses are prone to displacement, entanglement or partial bending during concrete pouring, causing the path after molding to deviate from the design trajectory, making it impossible to form the predetermined temperature gradient, or even causing fluid blockage inside the tube.

[0006] The position of the temperature regulating pipe cannot be fine-tuned after it is filled with liquid: After the concrete solidifies, the temperature regulating pipe is encased in it. If there is twisting or poor flow, the existing structure cannot be adjusted without damaging the test block, resulting in unreliable test data or the need to remake the test block, which is costly and time-consuming.

[0007] Therefore, existing technologies suffer from the problem that the temperature control tube is difficult to position and shape, and cannot be precisely fine-tuned during the shaping process. Utility Model Content

[0008] To address the problems in existing technologies regarding the difficulty in positioning and shaping the temperature control tube, and the inability to precisely fine-tune it during the shaping process, this invention provides a large-volume concrete crack resistance testing device:

[0009] A large-volume concrete crack resistance testing device.

[0010] Includes a temperature control tube, a shaping and limiting mechanism, an air filling mechanism, and a liquid supply mechanism;

[0011] The shaping and limiting mechanism includes a support plate, a shaping plug, a shaping valve, and a traction rope. The support plate is provided with a first through hole and a second through hole. The first free end of the temperature regulating tube passes through the first through hole and is then sealed by the shaping plug. The second free end of the temperature regulating tube passes through the second through hole and is then sealed by the shaping valve. The traction rope is disposed inside the temperature regulating tube, with one end passing through the first through hole and sealingly connected to the shaping plug, and the other end passing through the second through hole.

[0012] The crack resistance test first involves air filling, followed by temperature adjustment.

[0013] When inflation is required, the shaping valve is opened, and the inflation mechanism inflates the temperature regulating tube to make the temperature regulating tube expand and shape. At the same time, the traction rope can be pulled to finely adjust the position of the temperature regulating tube. After the temperature regulating tube expands and shapes, the inflation mechanism and the shaping limiting mechanism are removed.

[0014] When temperature regulation is required, the outlet of the liquid supply mechanism is connected to the first free end, and the return port of the liquid supply mechanism is connected to the second free end.

[0015] Furthermore,

[0016] The shaping and limiting mechanism further includes a first fixing member, which is disposed on the bearing plate and is used to fix the first free end of the temperature regulating tube.

[0017] Furthermore, the shaping and limiting mechanism also includes a second fixing member, which is disposed on the bearing plate and is used to fix the second free end of the temperature regulating tube.

[0018] Furthermore, the traction rope is a steel wire rope.

[0019] Furthermore, the end of the traction rope protruding from the shaped plug is sealed to the shaped plug through a sealing element.

[0020] Furthermore, the end of the traction rope near the shaping valve is in a suspended, free state.

[0021] Furthermore, the liquid supply mechanism includes a temperature-regulating tank and a liquid supply pump;

[0022] The first free end of the temperature regulating tube is connected to the outlet of the liquid supply pump, and the second free end of the temperature regulating tube is connected to the inner cavity of the temperature regulating tank.

[0023] The liquid in the temperature control tank is pumped into the first free end of the temperature control tube by the liquid supply pump, and then flows back to the temperature control tank from the second free end.

[0024] Furthermore, the liquid supply mechanism includes a heating rod, which is installed in the temperature control tank and its heating end extends into the temperature control tank.

[0025] Furthermore, the liquid supply mechanism also includes a cooling tank and a cooling pump;

[0026] The liquid in the cooling tank is pumped into the temperature regulating tank via the cooling pump.

[0027] Furthermore, the liquid supply mechanism also includes a temperature control switch;

[0028] The temperature control switch is installed in the temperature regulating tank, and its temperature measuring end extends into the temperature regulating tank;

[0029] When the temperature control switch detects that the temperature of the temperature regulating liquid is higher than the upper limit threshold, the temperature control switch controls the cooling pump to start, so as to drive the coolant at low temperature into the temperature regulating tank.

[0030] When the temperature control switch detects that the temperature of the temperature-regulating liquid is lower than the lower threshold, the temperature control switch controls the heating rod to start, so as to heat the temperature-regulating liquid in the temperature-regulating tank.

[0031] The beneficial effects of this utility model are:

[0032] This device utilizes a shaping and limiting mechanism that works in conjunction with an inflation mechanism. Before concrete pouring, a traction rope provides axial pre-tension and positioning for the temperature-regulating tube, while a bearing plate provides radial constraint on the side. The inflation mechanism inflates the tube uniformly through a shaping valve, ensuring the flexible temperature-regulating tube maintains its preset geometric path and cross-sectional shape under the pressure of the concrete slurry. This effectively prevents displacement, entanglement, or partial bending of the temperature-regulating tube during pouring. Simultaneously, the traction rope can be pulled to fine-tune the position of the temperature-regulating tube. After the temperature-regulating tube has been inflated and shaped, the inflation mechanism and the entire shaping and limiting mechanism can be completely removed, with the subsequent circulation of the temperature-regulating liquid handled solely by the liquid supply mechanism. Since the traction rope establishes the initial path of the temperature-regulating tube during the shaping stage, and a certain degree of interface freedom is maintained between the temperature-regulating tube and the test block after removing the limiting mechanism, the device allows for fine-tuning of the temperature-regulating tube's position only during the inflation and shaping process by pulling the traction rope. After the concrete solidifies, the temperature-regulating tube's position is fixed, and no further adjustments are needed. Attached Figure Description

[0033] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0034] Figure 1 This is a front view of the shaping and limiting mechanism in the large-volume concrete crack resistance testing device provided by this utility model embodiment;

[0035] Figure 2 This is a schematic diagram of the assembly state of the shaping and limiting mechanism and the temperature regulating tube provided in this embodiment of the utility model;

[0036] Figure 3 This is an exploded view of the temperature regulating tube, the shaping plug, the shaping valve, and the traction rope provided in the embodiment of this utility model.

[0037] Figure 4 This is a schematic diagram of the anti-cracking experimental device provided in this embodiment of the invention during temperature control.

[0038] Icons: 100, Temperature control tube; 110, First free end; 120, Second free end; 200, Shaping and limiting mechanism; 210, Support plate; 220, Shaping plug; 230, Shaping valve; 240, Traction rope; 250, First fixing component; 260, Second fixing component; 400, Liquid supply mechanism; 410, Temperature control tank; 420, Liquid supply pump; 430, Heating rod; 440, Cooling tank; 450, Cooling pump. Detailed Implementation

[0039] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] The terms “first”, “second”, etc., are used to distinguish similar objects, not to describe or indicate a specific order or sequence.

[0042] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent in such process, method, article, or apparatus / device.

[0043] This embodiment provides a large-volume concrete crack resistance testing device; please refer to [other documentation / reference]. Figures 1 to 4The device includes a temperature regulating tube 100, a shaping and limiting mechanism 200, an inflation mechanism, and a liquid supply mechanism 400. The shaping and limiting mechanism 200 includes a support plate 210, a shaping plug 220, a shaping valve 230, and a traction rope 240. The support plate 210 has a first insertion hole and a second insertion hole. The first free end 110 of the temperature regulating tube 100 passes through the first insertion hole and is then sealed by the shaping plug 220. The second free end 120 of the temperature regulating tube 100 passes through the second insertion hole and is then sealed by the shaping valve 230. The traction rope is disposed inside the temperature regulating tube 100, with one end passing through the... The first end is sealed to the shaping plug 220 after the first insertion hole, and the other end passes through the second insertion hole; the crack resistance test requires first performing an inflation operation and then a temperature adjustment operation; when an inflation operation is required, the inflation mechanism is used to inflate the shaping valve 230 to expand and shape the temperature adjustment tube 100. After the temperature adjustment tube 100 expands and shapes, the inflation mechanism and the shaping limiting mechanism 200 are removed; when a temperature adjustment operation is required, the outlet of the liquid supply mechanism 400 is connected to the first free end 110, and the return port of the liquid supply mechanism 400 is connected to the second free end 120.

[0044] In this embodiment, the temperature regulating tube 100 is made of a flexible polymer material, and its wall has elastic deformation capability. The support plate 210 serves as a positioning base and is made of metal plate or rigid plastic plate. The diameters of the first and second through holes are slightly larger than the outer diameter of the temperature regulating tube 100, so that the temperature regulating tube 100 can pass through smoothly while obtaining preliminary radial constraint. The shaping plug 220 is molded from elastic rubber material. Preferably, the front end of the shaping plug 220 has a tapered guide structure, and the rear end is provided with a threaded interface or snap-fit ​​interface for connection with the traction rope 240. Preferably, the shaping valve 230 is a one-way inflation valve, and its air inlet is provided with a standard quick-connect connector for cooperation with the inflation mechanism, and the air outlet is connected to the inner cavity of the temperature regulating tube 100. The traction rope 240 is made of steel wire rope with a diameter of 1mm to 2mm, and its surface can be coated with polytetrafluoroethylene coating to reduce the coefficient of friction with the inner wall of the temperature regulating tube 100.

[0045] In the preparation stage before concrete pouring, the operator first inserts the traction rope 240 into the temperature regulating pipe 100. One end of the traction rope 240 is fixedly connected to the shaping plug 220 through a sealing element, while the other end remains free. Then, the first free end 110 of the temperature regulating pipe 100 is passed through the first through hole of the support plate 210. The shaping plug 220 is inserted into the first free end 110 and axial pressure is applied to form an interference fit seal with the pipe opening. Next, the second free end 120 of the temperature regulating pipe 100 is passed through the second through hole of the support plate 210, and the shaping valve 230 is installed on the second free end 120. At this point, the free end of the traction rope 240 passes through the first through hole and is exposed. The operator applies axial tension through the traction rope 240 to keep the temperature regulating pipe 100 on both sides of the support plate 210 along a predetermined straight or curved path. After the shaping valve 230 is opened, the air filling mechanism fills the temperature regulating tube 100 with compressed air. Under the action of internal air pressure, the temperature regulating tube 100 expands radially, and the tube wall generates circumferential tensile stress, so that the cross-sectional shape of the temperature regulating tube 100 changes from a flat and relaxed state to a regular circle or ellipse. At the same time, the bending stiffness of the tube body is significantly improved, so that it can resist the lateral pressure and buoyancy of the concrete slurry during the concrete pouring process and maintain the preset spatial path unchanged.

[0046] After the concrete is poured and cured to the predetermined strength, the operator opens the shaping valve 230 to release pressure, then pulls out the shaping plug 220 from the first free end 110, removes the shaping valve 230 from the second free end 120, and simultaneously slides the bearing plate 210 off the temperature regulating pipe 100. At this point, the inflation mechanism and the shaping limiting mechanism 200 are completely removed, and the temperature regulating pipe 100 is embedded only in its own shape inside the concrete specimen. Both the first free end 110 and the second free end 120 of the temperature regulating pipe 100 are exposed on the surface of the specimen. Then, the outlet of the liquid supply mechanism 400 is connected to the first free end 110, and the return port of the liquid supply mechanism 400 is connected to the second free end 120. Activating the liquid supply mechanism 400 will circulate the temperature regulating liquid into the temperature regulating pipe 100, applying the set temperature field to the concrete specimen.

[0047] The inflation process provides temporary structural rigidity to the flexible temperature-regulating tube 100. When the internal air pressure is higher than the external environmental pressure, the tube wall experiences bidirectional tensile stress, significantly increasing the tube's flexural modulus. The shaping and limiting mechanism 200 provides end constraints and radial positioning during inflation, ensuring that the expanded temperature-regulating tube 100 does not deviate from its path due to axial contraction. After expansion and shaping, the internal steel wire rope of the temperature-regulating tube 100 provides axial pre-tensioning and guidance during inflation, preventing uncontrollable serpentine bending of the tube during inflation. After the concrete solidifies, the temperature-regulating tube is completely encased and fixed, and its position no longer changes; this device only allows for minor position adjustments via traction ropes during the inflation and shaping stage.

[0048] In this embodiment, the shaping and limiting mechanism 200 further includes a first fixing member 250, which is disposed on the bearing plate 210 and is used to fix the first free end 110 of the temperature regulating tube 100.

[0049] In this embodiment, the first fixing member 250 adopts an elastic claw structure or a clamping structure. The elastic claw structure includes at least three circumferentially distributed claws, the root of each claw is hinged to the support plate 210, the end of the claw is provided with a rubber gasket, and a locking nut is sleeved on the outside of the claw. When the locking nut is tightened, the claws contract concentrically to clamp the temperature regulating tube 100. The clamping structure uses an open metal ring in conjunction with a fastening bolt, and the inner diameter of the open ring matches the outer diameter of the temperature regulating tube 100. The first fixing member 250 is installed outside the first through hole of the support plate 210, and its central axis coincides with the central axis of the first through hole. After the operator passes the first free end 110 of the temperature regulating tube 100 through the first through hole and installs the shaping plug 220, the axial position of the first free end 110 is locked by the first fixing member 250.

[0050] In this embodiment, the shaping and limiting mechanism 200 further includes a second fixing member 260, which is disposed on the support plate 210 and used to fix the second free end 120 of the temperature regulating tube 100. The structure of the second fixing member 260 is the same as that of the first fixing member 250, adopting an elastic claw structure or a clamp structure, and is installed on the outside of the second through hole of the support plate 210. The difference from the first fixing member 250 is that the second fixing member 260 can be used to fix the shaping valve 230, or it can be used to fix the non-shaping valve 230 part of the tube body of the temperature regulating tube 100.

[0051] In this embodiment, the traction rope 240 is a steel wire rope. The traction rope 240 is preferably a galvanized steel wire rope with a galvanized layer on its surface to meet the corrosion resistance requirements of the alkaline environment of concrete. Both ends of the steel wire rope are fused to prevent the wires from unraveling. Simultaneously, the high bending stiffness of the steel wire rope makes it less prone to knotting or tangling within the temperature regulating pipe 100, allowing the steel wire rope to be easily inserted and withdrawn even when there are bent sections in the temperature regulating pipe 100.

[0052] In this embodiment, the end of the traction rope protruding from the shaped plug 220 is sealed to the shaped plug 220 via a sealing element. In this embodiment, the sealing element adopts a combined sealing structure, including an O-ring rubber seal and a metal clamping nut. The shaped plug 220 has a stepped hole axially formed at its center, the larger diameter section of which accommodates the anchor head at the end of the wire rope. The O-ring seal is installed on the stepped surface of the stepped hole, the wire rope passes through the central hole of the O-ring seal, and the metal clamping nut is screwed into the threaded hole at the end of the shaped plug 220, compressing the O-ring seal and causing it to expand radially to grip the wire rope.

[0053] The portion of the wire rope protruding from the shaping plug 220 can be used by the operator to grip and apply traction. The exposed section is also fitted with a protective sleeve to prevent the wire at the end of the rope from piercing the operator's fingers. During the dismantling phase after testing, the operator can quickly separate the shaping plug 220 from the wire rope by cutting the exposed section, without needing to disassemble the seal, thus improving operational efficiency.

[0054] In this embodiment, the end of the traction rope near the shaping valve 230 is in a suspended, free state. In this embodiment, the end of the traction rope near the shaping valve 230 is not fixed in any way, nor is an anchoring structure provided. More preferably, the end of the wire rope is treated with a molten ball to form a smooth ball with a diameter approximately 1.5 times the diameter of the wire rope, preventing the single filaments at the end of the wire rope from scratching the inner wall of the temperature regulating tube 100.

[0055] The design of the suspended free state is based on the following considerations: During inflation, the operator applies tension to the wire rope from one end of the shaping plug 220, and the wire rope is in a prestressed state of single-end tension within the temperature regulating tube 100. At this time, the end of the wire rope near the shaping valve 230 is unrestrained and can move freely within the temperature regulating tube 100. After the concrete is poured, the path of the temperature regulating tube 100 is fixed by the concrete. Due to the difference between the linear expansion coefficient of the wire rope and the linear expansion coefficient of the temperature regulating tube 100, if both ends of the wire rope are fixed during temperature changes, thermal stress accumulation will occur, which may lead to local wrinkles or indentations in the temperature regulating tube 100. The suspended free state allows the wire rope to freely expand and contract with temperature changes, eliminating the influence of thermal stress on the shape of the temperature regulating tube 100. When it is necessary to use a steel wire rope to finely adjust the posture of the temperature regulating tube 100, the operator applies or releases the tension on the steel wire rope from one end of the shaping plug 220. The end of the steel wire rope near the shaping valve 230 is the free end and can slide inside the temperature regulating tube 100. This single-end traction method is easier to control the traction force and displacement than traction from both ends at the same time. The operator can judge the state changes of the temperature regulating tube 100 by feel and achieve fine adjustment.

[0056] In this embodiment: the liquid supply mechanism 400 includes a temperature control tank 410 and a liquid supply pump 420; the liquid in the temperature control tank 410 is pumped into the second free end 120 of the temperature control tube 100 by the liquid supply pump 420, and then flows back to the temperature control tank 410.

[0057] In this embodiment, the temperature-regulating tank 410 preferably adopts a double-layer stainless steel structure, with an outer insulation layer and an inner liquid storage chamber. A level gauge is installed on the side wall of the temperature-regulating tank 410. The liquid supply pump 420 is a miniature magnetic drive pump. The inlet of the liquid supply pump 420 is connected to the outlet of the temperature-regulating tank 410 via a hose, and the outlet is connected to the second free end 120 of the temperature-regulating tube 100 via a hose. The first free end 110 of the temperature-regulating tube 100 is connected to the outlet of the liquid supply pump 420 via a hose.

[0058] During the temperature control operation, the supply pump 420 draws temperature control liquid from the temperature control tank 410. After being pressurized by the supply pump 420, the temperature control liquid enters the temperature control tube 100, flows through the entire temperature control tube 100, and then flows out, returning to the temperature control tank 410 via the return hose. This flow direction design ensures that the flow direction of the temperature control liquid in the temperature control tube 100 is opposite to the airflow direction during the inflation operation.

[0059] This embodiment further specifies that the liquid supply mechanism 400 includes a heating rod 430, which is installed in the temperature regulating tank 410, with its heating end extending into the temperature regulating tank 410. In this embodiment, the heating rod 430 is a single-ended heating element with a stainless steel sheath. A temperature sensor feeds back the real-time temperature inside the temperature regulating tank 410 to the controller. The controller calculates the deviation between the set temperature and the actual temperature, and outputs a corresponding thyristor trigger signal based on the magnitude, accumulation, and trend of the deviation to adjust the average heating power of the heating rod 430.

[0060] In practical applications, when simulating the mechanical properties of concrete under high-temperature conditions, the operator sets the target temperature via the controller, and the heating element 430 automatically starts heating. Once the set temperature is reached, the system enters a heat preservation state, with the heating element 430 intermittently operating to maintain a constant temperature. The temperature-regulating fluid is typically a mixture of water and ethylene glycol.

[0061] In this embodiment: the liquid supply mechanism 400 further includes a cooling tank 440 and a cooling pump 450; the input end of the cooling pump 450 is connected to the cooling tank 440, and the output end of the cooling pump 450 is connected to the temperature regulating tank 410; the liquid in the cooling tank 440 is sent to the temperature regulating tank 410 via the cooling pump 450.

[0062] In this embodiment, the cooling tank 440 is used to store the low-temperature temperature-regulating liquid. A coil-type evaporator is installed inside the cooling tank 440, which is connected to an external compression refrigeration unit. The cooling pump 450 is preferably a low-temperature magnetically driven pump, with the pump body and piping covered with an insulation layer. The output end of the cooling pump 450 is connected to the liquid inlet of the temperature-regulating tank 410 via a solenoid valve. The solenoid valve is a normally closed two-position two-way valve with a brass or stainless steel body and low-temperature resistant fluororubber seals.

[0063] During the test preparation phase, operators inject temperature-regulating fluid into cooling tank 440 and start the refrigeration unit to cool the fluid to a preset low temperature. The temperature of the temperature-regulating fluid in cooling tank 440 is monitored by an independent temperature sensor. When the temperature reaches the set value, the refrigeration unit automatically shuts down to save energy. When simulating a low-temperature environment is required, operators activate cooling pump 450 and the solenoid valve. The low-temperature temperature-regulating fluid in cooling tank 440 is pumped into temperature-regulating tank 410, where it mixes with the existing temperature-regulating fluid. The temperature of the mixture is measured by a temperature sensor in temperature-regulating tank 410. When the temperature drops to the target value, cooling pump 450 and the solenoid valve are shut off.

[0064] The cooling system and heating system of this embodiment work together to enable the temperature control tank 410 to quickly respond to the temperature curve set by the user within a wide temperature range.

[0065] In this embodiment, the liquid supply mechanism 400 further includes a temperature control switch; the temperature control switch is installed in the temperature regulating tank 410, and its temperature measuring end extends into the temperature regulating tank 410; when the temperature control switch detects that the temperature of the temperature regulating liquid is lower than the lower threshold, the temperature control switch controls the cooling pump 450 to start, so as to drive the temperature regulating liquid in the low temperature state into the temperature regulating tank 410; when the temperature control switch detects that the temperature of the temperature regulating liquid is higher than the upper threshold, the temperature control switch controls the heating rod 430 to start, so as to heat the temperature regulating liquid in the temperature regulating tank 410.

[0066] The specific values ​​of the lower and upper thresholds are set according to the test requirements. The difference between them, known as the hysteresis, is used to prevent frequent start-stop of the control system. Typical settings are: lower threshold 5°C, upper threshold 7°C, and hysteresis 2°C. When the temperature inside the temperature control tank 410 rises above 7°C, the temperature control switch starts the cooling pump 450, and the low-temperature temperature control liquid is replenished from the cooling tank 440 into the temperature control tank 410, causing the temperature of the temperature control tank 410 to begin to decrease. When the temperature drops below 5°C, the temperature control switch shuts off the cooling pump 450. Similarly, when the temperature rises above the set upper threshold, the heating rod 430 starts heating; when the temperature drops below the lower threshold, the heating rod 430 stops heating.

[0067] The control logic of the temperature control switch can employ an interlocking mechanism, meaning that the heating element 430 and the cooling pump 450 cannot operate simultaneously, preventing energy waste and equipment damage. The interlocking circuit is implemented through series connection of relay contacts. The normally closed auxiliary contact of the cooling pump 450 is connected in series in the control circuit of the heating element 430, and the normally closed auxiliary contact of the heating element 430 is connected in series in the control circuit of the cooling pump 450. In some experiments requiring the simulation of periodic temperature fluctuations, the temperature control switch can also employ a non-interlocking mechanism, allowing the heating element 430 and the cooling pump 450 to operate simultaneously for a faster rate of temperature change. However, this method consumes more energy and is generally only used in experiments with specific requirements.

[0068] The temperature control switch in this embodiment enables automatic maintenance of the temperature in the temperature control tank 410, eliminating the need for continuous monitoring and manual intervention by test personnel. In long-term tests, such as a 72-hour continuous concrete temperature fatigue test, the automatic control function of the temperature control switch significantly reduces labor costs, eliminates temperature fluctuations caused by manual operation, and improves the repeatability of test data.

[0069] The technical solution of this utility model has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the protection scope of this utility model is obviously not limited to these specific embodiments. Without departing from the principle of this utility model, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of this utility model.

Claims

1. A large-volume concrete crack resistance testing device, characterized in that: It includes a temperature control tube (100), a shaping and limiting mechanism (200), an air filling mechanism, and a liquid supply mechanism (400). The shaping and limiting mechanism (200) includes a support plate (210), a shaping plug (220), a shaping valve (230), and a traction rope (240). The support plate (210) is provided with a first insertion hole and a second insertion hole. The first free end (110) of the temperature regulating tube (100) passes through the first insertion hole and is then sealed by the shaping plug (220). The second free end (120) of the temperature regulating tube (100) passes through the second insertion hole and is then sealed by the shaping valve (230). The traction rope (240) is disposed inside the temperature regulating tube (100), with one end passing through the first insertion hole and being sealed to the shaping plug (220), and the other end passing through the second insertion hole. The crack resistance test first involves air filling, followed by temperature adjustment. When inflation is required, the shaping valve (230) is opened, and the inflation mechanism inflates the temperature regulating tube (100) to expand and shape it. At the same time, the traction rope (240) is pulled to finely adjust the position of the temperature regulating tube (100). After the temperature regulating tube (100) expands and shapes, the inflation mechanism and the shaping limiting mechanism (200) are removed. When temperature regulation is required, the outlet of the liquid supply mechanism (400) is connected to the first free end (110), and the return port of the liquid supply mechanism (400) is connected to the second free end (120).

2. The large-volume concrete crack resistance testing device according to claim 1, characterized in that: The shaping and limiting mechanism (200) further includes a first fixing member (250), which is disposed on the bearing plate (210) and is used to fix the first free end (110) of the temperature regulating tube (100).

3. The large-volume concrete crack resistance testing device according to claim 2, characterized in that: The shaping and limiting mechanism (200) further includes a second fixing member (260), which is disposed on the support plate (210) and is used to fix the second free end (120) of the temperature regulating tube (100).

4. The large-volume concrete crack resistance testing device according to claim 3, characterized in that: The traction rope (240) is a steel wire rope.

5. The large-volume concrete crack resistance testing device according to claim 4, characterized in that: The end of the traction rope that protrudes from the shaping plug (220) is sealed to the shaping plug (220) by a sealing element.

6. The large-volume concrete crack resistance testing device according to claim 5, characterized in that: The end of the traction rope near the shaping valve (230) is in a suspended and free state.

7. The large-volume concrete crack resistance testing device according to claim 6, characterized in that: The liquid supply mechanism (400) includes a temperature control tank (410) and a liquid supply pump (420). The first free end (110) of the temperature regulating tube (100) is connected to the outlet of the liquid supply pump (420), and the second free end (120) of the temperature regulating tube (100) is connected to the inner cavity of the temperature regulating tank (410). The liquid in the temperature control tank (410) is pumped into the first free end (110) of the temperature control tube (100) by the liquid supply pump (420), and then flows back to the temperature control tank (410) from the second free end (120).

8. The large-volume concrete crack resistance testing device according to claim 7, characterized in that: The liquid supply mechanism (400) includes a heating rod (430) which is installed in the temperature control tank (410) and its heating end extends into the temperature control tank (410).

9. The large-volume concrete crack resistance testing device according to claim 8, characterized in that: The liquid supply mechanism (400) also includes a cooling tank (440) and a cooling pump (450). The liquid in the cooling tank (440) is sent to the temperature regulating tank (410) via the cooling pump (450).

10. The large-volume concrete crack resistance testing device according to claim 9, characterized in that: The liquid supply mechanism (400) also includes a temperature control switch; The temperature control switch is installed in the temperature regulating tank (410), and its temperature measuring end extends into the temperature regulating tank (410); When the temperature control switch detects that the temperature of the temperature regulating liquid is higher than the upper limit threshold, the temperature control switch controls the cooling pump (450) to start, so as to drive the coolant at low temperature into the temperature regulating tank (410). When the temperature control switch detects that the temperature of the temperature regulating liquid is lower than the lower threshold, the temperature control switch controls the heating rod (430) to start, so as to heat the temperature regulating liquid in the temperature regulating tank (410).

Images