An apparatus and method for measuring the expansion stress caused by an expansion agent.

Abstract

This invention provides an apparatus and method for measuring the expansion stress caused by an expanding agent. The reaction frame includes a base, with vertically arranged supports fixed at both ends of the base. A pressure plate is supported between the tops of the vertical supports. A bolt is installed in the middle of the pressure plate. The bottom end of the bolt connects to a cylindrical mold, the interior of which is the reaction space for the expanding agent. A sleeve is pre-set at the outer end of the cylindrical mold, with a space reserved between the cylindrical mold and the sleeve. Two iron blocks of the same thickness are pre-set on the inner wall of the cylindrical mold. The outer end faces of the two iron blocks are each connected to a thin rod of the same size. The outer top of the thin rod is connected to a strain gauge that can directly measure stress and contacts the inner wall of the sleeve. A feeding port is pre-set at the top of the cylindrical mold. By using the equivalent cross-sectional area of ​​the iron blocks and thin rods to calculate the expansion stress caused by the expanding agent, the problem of inaccurate measurement of expansion stress is solved in previous direct measurement processes where the strain gauge was burned due to excessive temperature caused by the expansion agent reaction.

Description

Technical Field

[0001] This invention relates to the field of expansion stress measurement technology, and in particular to an apparatus and method for measuring the expansion stress caused by an expansion agent. Background Technology

[0002] An expansive agent is a material that expands under specific conditions and is commonly used in construction, engineering, and mining. When an expansive agent comes into contact with other substances, its volume increases dramatically, potentially generating expansion stress. In construction, expansive agents are often used to fill and seal cracks, fissures, and cavities; in mining and oilfield extraction, they can be used for fracturing; and in concrete manufacturing, they can increase the volume of concrete and improve its performance. To ensure safety and reliability, the potential expansion stress caused by expansive agents must be measured and assessed to avoid possible losses or hazards. In construction sites, for example, in the early prediction of the fabrication of expansion piles and expansion anchors, predictions of pull-out forces and expansion stresses are used to determine the optimal expansive agent content, thereby achieving economic benefits.

[0003] In existing technologies, there are two main methods for measuring the expansion stress caused by expanding agents in the laboratory: mechanical measurement and electronic measurement. Mechanical measurement typically uses sensors such as strain gauges or deformability meters to detect the deformation of the object and thus calculate the expansion stress. Electronic measurement, on the other hand, uses electronic sensing devices to directly measure the expansion stress. In existing measurement methods, the expansion agent reaction releases a large amount of heat, causing a sharp rise in temperature. The strain gauge sensing devices used in the past cannot withstand high temperatures and are often burned out in high-temperature environments, making it impossible to accurately measure the expansion stress. Furthermore, the damage to the instruments results in significant economic losses. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides an apparatus and method for measuring the expansion stress caused by an expansion agent. This apparatus uses the cross-sectional area of ​​an iron block and a thin rod as an equivalent substitute to calculate the expansion stress caused by the expansion agent, thus solving the problem that in the previous direct measurement process, the expansion agent reaction caused the strain gauge to burn out due to excessive temperature, which made it impossible to accurately measure the expansion stress.

[0005] To achieve the above-mentioned technical features, the present invention aims to provide a device for measuring the expansion stress caused by an expanding agent in a laboratory setting. The device includes a reaction frame, a base, and vertically arranged supports fixed to the top of both ends of the base. A pressure plate is supported between the tops of the vertical supports, and a wedge block is provided at the connection between the pressure plate and the vertical supports. A bolt is provided in the middle of the pressure plate, and downward pressure is applied during the tightening process. The bottom end of the bolt is connected to a cylindrical mold, the interior of which is a reaction space for the expanding agent. A sleeve is pre-set at the outer end of the cylindrical mold, and a space is reserved between the cylindrical mold and the sleeve. Two iron blocks of the same thickness are pre-set on the inner wall of the cylindrical mold, and thin rods of the same size are connected to the outer end faces of the two iron blocks. The outer top of the thin rods is connected to strain gauges that can directly measure stress and contact the inner wall of the sleeve. A feeding port is pre-set at the top of the cylindrical mold.

[0006] In the field operation, it includes a rod-shaped metal pressure pump. The upper end of the rod-shaped metal pressure pump is connected to a pressure display gauge, and the lower end is connected to an electric heater. The lower end of the rod-shaped metal pressure pump is designed as a four-section mold box. The mold box contains reaction materials with different contents of expansion agent. Block aluminum foil is connected around the same position of the mold box. The rear end of the block aluminum foil is connected to a grating. Water injection pipe and liquid nitrogen injection plastic pipe are connected to both sides of the mold box.

[0007] The cylindrical mold is made of transparent material, allowing observation of the expansion agent reaction process.

[0008] The wedge block has a wedge-shaped structure and is used to apply a force to limit the displacement of the pressure plate by pressing the wedge block during the experiment. The pressure plate has a threaded hole machined in the center for mounting bolts. Tightening the bolts downwards provides a force to fix the cylindrical mold and apply force to limit the displacement of the cylindrical mold.

[0009] The iron blocks have the same elastic modulus. The maximum expansion stress generated by the reaction of the expansion agent in the cylindrical mold acts on the iron blocks. The expansion stress caused by the expansion agent is measured by equivalent substitution of the iron blocks. The surface of the iron blocks is coated with heat insulation material.

[0010] The iron block and the inner wall of the cylindrical mold are slidably connected by a slide rail structure that can lock the height. The cross-sectional area of ​​the thin rod and the elastic modulus of the iron block are fixed parameters. During the measurement process, the expansion stress is measured by using different equivalent cross-sectional areas. The strain gauge is connected to a computer monitor via a signal line, and the strain gauge is used to directly measure the stress acting on the thin rod. The sleeve has a pre-set groove on its inner wall at the location of the slide rail structure. The movement of the iron block can drive the thin rod to move up and down in the groove, thereby measuring the maximum expansion stress of the expansion agent reaction. The feeding port is clamped with a water stop valve to seal the cylindrical mold. When feeding, the water stop valve is opened to add the expanding agent into the cylindrical mold.

[0011] The electric heater is a device that converts electrical energy into heat energy, which can heat the entire device, vaporize liquid nitrogen, melt ice, and allow the reaction in the mold box to continue. The mold box is made of absolutely rigid metal, and the block aluminum foil connected around it is made of absolutely rigid metal with a known elastic modulus. The aluminum foil has excellent heat insulation properties, which can avoid the problem of inaccurate measurement caused by temperature.

[0012] The pressure measured by the pressure gauge is the deformation pressure of the rod-shaped metal pressure pump itself and the pressure of the surrounding rock. When the pressure drops sharply, it indicates that there are cracks in the surrounding rock. The water injection pipe is used for water injection, and the liquid nitrogen injection plastic pipe is used for liquid nitrogen injection. Liquid nitrogen can cause the temperature of the entire device to drop sharply, causing the water to freeze and stopping the reaction. The grating is a sensitive testing device that can sense and measure the inhomogeneity of the surrounding rock as the rod-shaped metal pressure pump penetrates deep into the cave.

[0013] A method for stress measurement using a device for measuring the expansion stress caused by an expanding agent, the experimental process in the laboratory includes the following steps: Step 1.1: Make a cylindrical mold and place it on the reaction frame; Step 1.2: Connect the iron block, thin rod and strain gauge, pull the iron block along the slide rail structure and put the thin rod into the slide groove of the cylindrical mold, and observe the reading of the strain gauge display at this time; Step 1.3: Perform zero-point adjustment by tightening the bolts until the strain gauge display reading is 0. Step 1.4: Open the water stop valve, prepare a certain amount of water-cement ratio sample and inject it into the cylindrical mold through the feeding port, and put in the expansion agent sample to start the reaction. Observe and record the strain gauge reading, and calculate the expansion stress caused by the expansion agent by equivalent substitution of cross-sectional area.

[0014] A method for stress measurement using a device for measuring the expansion stress caused by an expanding agent, during on-site experimental procedures, includes the following steps: Step 2.1, Ingredient preparation: Prepare different contents of expansion agent, namely 10%, 15%, 20%, and 25%, and place them in the mold box made of rod-shaped metal pressure pump; Step 2.2: Install the pressure gauge and electric heater, and connect the water injection pipe and liquid nitrogen injection plastic pipe to each mold box; Step 2.3: Insert the assembled device into the exploratory hole, inject water into the mold box through the water injection pipe, start the reaction, and record the pressure display gauge and grating readings.

[0015] The present invention has the following beneficial effects: In the laboratory; 1. The expansion stress caused by the expansion agent is calculated by equivalent substitution of the cross-sectional area of ​​the iron block and thin rod. This solves the problem that in the previous direct measurement process, the expansion agent reaction caused the strain gauge to burn out due to excessive temperature, thus making it impossible to accurately measure the expansion stress.

[0016] 2. The measurement process can achieve the ideal effect of controlling variables. By standardizing the use of cylindrical mold dimensions, the half-size of the cylindrical mold, the water-cement ratio during the reaction of the expanding agent, and the quality of the expanding agent can be controlled to achieve the control of variables in the experiment.

[0017] 3. The entire device is relatively convenient and can be installed indoors. It is not affected by factors such as terrain or space, achieving an ideal effect of being economical and practical.

[0018] On site: 1. The reaction can be controlled in real time by temperature effect. When the reaction needs to be stopped, liquid nitrogen can be injected to freeze the water. If the reaction needs to continue, the temperature can be raised by an electric heater, the liquid nitrogen will vaporize, the frozen water will melt, and the reaction will continue.

[0019] 2. By prefabricating different segments and different contents of expansion agent for exploratory tunneling, the most suitable expansion agent content can be found for the prefabrication of expansion piles and expansion anchors in the later stage.

[0020] 3. By using a pressure display instrument, rock strata cracking can be predicted. During the cave exploration process, when rock strata cracking is encountered, the pressure reading on the display instrument decreases sharply. By observing and measuring with a grating, the displacement data obtained is more accurate.

[0021] 4. By using the aluminum foil around the wall of the segmented mold box, the device can be used as a tool for early prediction. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Figure 1 This is a plan view of the present invention.

[0024] Figure 2 This is a structural diagram of the cylindrical mold, cylinder, and connecting components of the present invention.

[0025] Figure 3 This is a plan view of the slide groove of the present invention.

[0026] Figure 4 This is a structural diagram of the bidirectional zipper of the present invention.

[0027] Figure 1-4In the middle: 1. Base, 2. Vertical support, 3. Pressure plate, 4. Wedge block, 5. Bolt, 6. Cylindrical mold, 7. Sleeve, 8. Thin rod, 9. Iron block, 10. Strain gauge, 11. Slide rail structure, 12. Feed port, 13. Water stop valve; Figure 5 This is a diagram of the device of the present invention.

[0028] Figure 6 This is a diagram of the grating and aluminum foil connection device of the present invention.

[0029] Figure 5-6 In the middle: pressure display gauge 21, electric heater 22, rod-shaped metal pressure pump 23, liquid nitrogen injection plastic tube 24, water injection conveying tube 25, block aluminum foil 26, grating 41; 10% expanding agent sample 31, 15% expanding agent sample 32, 20% expanding agent sample 33, 25% expanding agent sample 34. Detailed Implementation

[0030] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0031] Example 1: See Figure 1-4 A device for measuring the expansion stress caused by an expanding agent, in a laboratory setting, includes a reaction frame. The reaction frame includes a base 1, with vertically arranged vertical supports 2 fixed at both ends of the base 1. A pressure plate 3 is supported between the tops of the vertical supports 2. A wedge block 4 is provided at the connection between the pressure plate 3 and the vertical supports 2. A bolt 5 is provided in the middle of the pressure plate 3. The bolt 5 applies downward pressure during the rotation and tightening process. The bottom end of the bolt 5 is connected to a cylindrical mold 6. The interior of the cylindrical mold 6 is a reaction space for the expanding agent. A sleeve 7 is pre-set at the outer end of the cylindrical mold 6. A space is reserved between the cylindrical mold 6 and the sleeve 7. Two iron blocks 9 of the same thickness are pre-set on the inner wall of the cylindrical mold 6. The outer end faces of the two iron blocks 9 of the same thickness are each connected to a thin rod 8 of the same size. The outer top end of the thin rod 8 is connected to a strain gauge 10 that can directly measure the stress and is in contact with the inner wall of the sleeve 7. A feeding port 12 is pre-set at the top of the cylindrical mold 6. This device uses the equivalent cross-sectional area of ​​an iron block or thin rod to calculate the expansion stress caused by the expansion agent, thus solving the problem that in the previous direct measurement process, the expansion agent reaction caused the strain gauge to burn out due to excessive temperature, making it impossible to accurately measure the expansion stress.

[0032] Furthermore, the cylindrical mold 6 is made of a transparent material, allowing observation of the expansion agent reaction process.

[0033] Furthermore, the wedge block 4 adopts a wedge-shaped structure, which is used to apply a force to limit the displacement of the pressure plate 3 by pressing the wedge block 4 during the experiment.

[0034] Furthermore, the center of the pressure plate 3 is machined with a threaded hole for mounting bolts 5, and the force for fixing the cylindrical mold 6 and applying force to limit the displacement of the cylindrical mold 6 is provided by tightening the bolts 5 downward.

[0035] Furthermore, the iron blocks 9 have the same elastic modulus, and the maximum expansion stress generated by the reaction of the expansion agent in the cylindrical mold 6 acts on the iron blocks 9. The expansion stress caused by the expansion agent is measured by equivalent substitution of the iron blocks 9, and the surface of the iron blocks 9 is coated with heat insulation material.

[0036] Furthermore, the iron block 9 and the inner wall of the cylindrical mold 6 are slidably connected by a slide rail structure 11 that can lock the height.

[0037] Furthermore, the cross-sectional area of ​​the thin rod 8 and the elastic modulus of the iron block 9 are fixed parameters. During the measurement process, the expansion stress is measured by substituting different equivalent cross-sectional areas.

[0038] Furthermore, the strain gauge 10 is connected to a computer display via a signal line, and the strain gauge 10 is used to directly measure the stress acting on the thin rod 8.

[0039] Furthermore, a groove is pre-set on the inner wall of the sleeve 7, located at the position of the slide rail structure 11. The movement of the iron block 9 can drive the thin rod 8 to move up and down in the groove, thereby measuring the maximum expansion stress of the expansion agent reaction.

[0040] Furthermore, the feeding port 12 is clamped by a water stop valve 13 to seal the cylindrical mold 6. When feeding, the water stop valve 13 is opened to add the expanding agent into the cylindrical mold 6.

[0041] Furthermore, the cylindrical mold 6 can be made with different radii to facilitate control of the volume variation in the expansion agent reaction experiment.

[0042] Example 2: A method for stress measurement using a device for measuring the expansion stress caused by an expanding agent, the experimental process in the laboratory includes the following steps: Step 1.1: Make cylindrical mold 6 and place cylindrical mold 6 on the reaction frame; Step 1.2: Connect the iron block 9, thin rod 8 and strain gauge 10, pull the iron block 9 along the slide rail structure 11, and put the thin rod 8 into the slide groove of the cylindrical mold 6. Observe the reading of the strain gauge 10 display at this time. Step 1.3: Perform zero-point adjustment by tightening bolt 5 until the strain gauge 10 display shows a reading of 0. Step 1.4: Open the water stop valve 13, prepare a certain amount of water-cement ratio sample and inject it into the cylindrical mold 6 through the feeding port 12, and put in the expansion agent sample to start the reaction. Observe and record the strain gauge display reading, and calculate the expansion stress caused by the expansion agent by equivalent substitution of cross-sectional area.

[0043] Other samples with different proportions were added using the same method, and their expansion stress was measured.

[0044] Example 3: See Figure 5-6 In the field operation, the rod-shaped metal pressure pump 23 is connected to the pressure display gauge 21 at the upper end and the electric heater 22 at the lower end. The lower end of the rod-shaped metal pressure pump 23 is designed as a four-section mold box. The mold box contains reaction materials with different contents of expansion agent. Block aluminum foil 26 is connected around the same position of the mold box. The rear end of the block aluminum foil 26 is connected to the grating 41. Water injection pipe 25 and liquid nitrogen injection plastic pipe 24 are connected to both sides of the mold box.

[0045] Furthermore, the electric heater 22 is a device that converts electrical energy into heat energy, which can heat the entire device, vaporize liquid nitrogen, melt ice, and allow the reaction in the mold box to continue.

[0046] Furthermore, the mold box is made of an absolutely rigid metal, and the block aluminum foil 26 connected around it is an absolutely rigid metal with a known elastic modulus. The aluminum foil has excellent heat insulation properties, which can avoid the problem of inaccurate measurement caused by temperature.

[0047] Furthermore, the pressure measured by the pressure display gauge 21 is the deformation pressure of the rod-shaped metal pressure pump 23 itself and the pressure of the surrounding rock. When the pressure decreases sharply, it indicates that there are cracks in the surrounding rock.

[0048] Furthermore, the water injection pipe 25 is used for water injection, and the liquid nitrogen injection plastic pipe 24 is used for liquid nitrogen injection. Liquid nitrogen can cause the temperature of the entire device to drop sharply, causing the water to freeze and stopping the reaction. Furthermore, the grating 41 is a sensitive testing device that can sense and measure the inhomogeneity of the surrounding rock as the rod-shaped metal pressure pump 23 penetrates the burrow.

[0049] Furthermore, by obtaining the pressure, non-uniformity, optimal expansion agent content, and lateral deformation of the surrounding rock, expansion piles and expansion anchors can be pre-tested.

[0050] Furthermore, the aluminum foil in the 23 segments of the rod-shaped metal pressure pump can be used as an early prediction tool to test the pull-out force.

[0051] Example 4: A method for stress measurement using a device for measuring the expansion stress caused by an expanding agent, during on-site experimental procedures, includes the following steps: Step 2.1, Prepare the ingredients by preparing different contents of expansion agent, namely 10%, 15%, 20% and 25%, and place them in the mold box made by the rod-shaped metal pressure pump 23; Step 2.2: Install the pressure gauge 21 and the electric heater 22, and connect the water injection pipe 25 and the liquid nitrogen injection plastic pipe 24 to each mold box; Step 2.3: Insert the assembled device into the exploratory hole, inject water into the mold box through the water injection pipe 25, start the reaction, and record the readings of the pressure display gauge 21 and the grating 41.

Claims

1. A device for measuring the expansion stress caused by an expanding agent, characterized in that: In the laboratory, a reaction frame is included, which includes a base (1). Vertical supports (2) are fixed at the top of both ends of the base (1). A pressure plate (3) is installed between the tops of the vertical supports (2). A wedge block (4) is provided at the connection between the pressure plate (3) and the vertical support (2). A bolt (5) is provided in the middle of the pressure plate (3). The bolt (5) applies downward pressure during the rotation and tightening process. The bottom end of the bolt (5) is connected to a cylindrical mold (6). The inside of the cylindrical mold (6) is a reaction space for the expansion agent. A sleeve (7) is preset at the outer end of the cylindrical mold (6). A space is reserved between the cylindrical mold (6) and the sleeve (7). Two iron blocks (9) of the same thickness and elastic modulus are preset on the inner wall of the cylindrical mold (6). The surface of the iron blocks (9) is coated with heat insulation material. The outer end faces of the two iron blocks (9) of the same thickness are each connected to a thin rod (8) of the same size. The cross-sectional area of ​​8) and the elastic modulus of the iron block (9) are determined parameters. During the measurement process, the cross-sectional area of ​​the iron block (9) and the thin rod (8) are used to replace the expansion stress caused by the expansion agent. The iron block (9) and the inner wall of the cylindrical mold (6) are connected by a sliding rail structure (11) that can lock the height. The inner wall of the sleeve (7) is pre-set with a sliding groove. The movement of the iron block (9) can drive the thin rod (8) to move up and down in the sliding groove, thereby measuring the maximum expansion stress of the expansion agent reaction. The outer top of the thin rod (8) is connected to a strain gauge (10) that can directly measure the stress and is in contact with the inner wall of the sleeve (7). The strain gauge (10) is connected to the computer monitor through a signal line. The top of the cylindrical mold (6) is pre-set with a feeding port (12). The feeding port (12) is clamped with a water stop valve (13) to seal the cylindrical mold (6). In the field operation, a rod-shaped metal pressure pump (23) is used. The upper end of the rod-shaped metal pressure pump (23) is connected to a pressure display gauge (21), and the lower end is connected to an electric heater (22). The lower end of the rod-shaped metal pressure pump (23) is designed as a four-section mold box. Different reaction materials with different expansion agent contents are placed in the mold box. Block aluminum foil (26) is connected around the same position of the mold box. The rear end of the block aluminum foil (26) is connected to a grating (41). Water injection pipe (25) and liquid nitrogen injection plastic pipe (24) are connected to both sides of the mold box. The electric heater (22) can heat the entire field measurement. The components vaporize liquid nitrogen and melt ice to allow the reaction in the mold box to continue; the water injection pipe (25) is used for water injection, and the liquid nitrogen injection plastic pipe (24) is used for liquid nitrogen injection. Liquid nitrogen can lower the temperature of the on-site measuring components and freeze the water to stop the reaction; the pressure display gauge (21) measures the deformation pressure of the rod-shaped metal pressure pump (23) and the pressure of the surrounding rock. When the pressure drops sharply, it indicates that there are cracks in the surrounding rock; the grating (41) is used to sense and measure the inhomogeneity of the surrounding rock during the process of the rod-shaped metal pressure pump (23) going deep into the cave.

2. The device for measuring the expansion stress caused by the expanding agent according to claim 1, characterized in that: The cylindrical mold (6) is made of transparent material, allowing observation of the expansion agent reaction process.

3. The device for measuring the expansion stress caused by the expanding agent according to claim 1, characterized in that: The wedge block (4) adopts a wedge-shaped structure and is used to apply a force to limit the displacement of the pressure plate (3) by tightening the wedge block (4) during the experiment. The pressure plate (3) has a threaded hole for installing bolts (5) at its center. The force is used to fix the cylindrical mold (6) and apply a force to limit the displacement of the cylindrical mold (6) by tightening the bolts (5) downward.

4. A method for stress measurement using the apparatus for measuring the expansion stress caused by an expanding agent as described in any one of claims 1-3, characterized in that, The experimental process in the laboratory includes the following steps: Step 1.1, make a cylindrical mold (6) and place the cylindrical mold (6) on the reaction frame; Step 1.2: Connect the iron block (9), thin rod (8) and strain gauge (10), pull the iron block (9) along the slide rail structure (11) and put the thin rod (8) into the groove of the sleeve (7), and observe the reading of the strain gauge (10) display instrument at this time; Step 1.3, perform zero-point adjustment, tighten bolt (5) until the strain gauge (10) display shows a reading of 0; Step 1.4: Open the water stop valve (13), prepare a certain amount of water-cement ratio sample and inject it into the cylindrical mold (6) through the feeding port (12), and put in the expansion agent sample to start the reaction. Observe and record the strain gauge reading. Calculate the expansion stress caused by the expansion agent by equivalent substitution of the cross-sectional area of ​​the iron block (9) and the thin rod (8).

5. A method for stress measurement using the apparatus for measuring the expansion stress caused by the expanding agent as described in claim 1, characterized in that, The on-site operation experiment process includes the following steps: Step 2.1, Prepare the ingredients by preparing different contents of expansion agent, namely 10%, 15%, 20% and 25%, and place them in the mold box made by the rod-shaped metal pressure pump (23); Step 2.2: Install the pressure gauge (21) and the electric heater (22), and connect the water injection pipe (25) and the liquid nitrogen injection plastic pipe (24) to each mold box; Step 2.3: Insert the assembled device into the burrow, inject water into the mold box through the water injection pipe (25), start the reaction, and record the readings of the pressure display (21) and the grating (41).

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