Testing device and method for soft rock lossless water immersion and multi-direction deformation monitoring

Abstract

The invention discloses a testing device and method for soft rock lossless water immersion and multidirectional deformation monitoring, the testing device comprises a box body, an opening and closing door is hinged to the box body, a control panel is arranged on the box body, and a refrigerating unit, an electric heating pipe, a weighing sensor, a laser sensor and a temperature and humidity sensor are arranged in the box body. A mist inlet communicated with the inside and the outside of the box body is formed in the wall surface of the box body, an atomization humidifier is arranged outside the box body, and the atomization humidifier is connected to the mist inlet through a pipeline; the refrigerating unit and the electric heating pipe are used for adjusting the temperature in the box body, the weighing sensor is used for weighing the weight of the soft rock sample, the laser sensor is used for measuring the shape change condition of the soft rock sample, and the temperature and humidity sensor is used for measuring the temperature and humidity in the box body. According to the invention, nondestructive water immersion of the soft rock sample is realized, real-time and accurate acquisition of weight and multidirectional expansion deformation data of the soft rock sample in a water absorption process is realized, and the expansion characteristics of the soft rock in all directions can be accurately evaluated.

Description

Technical Field

[0001] The present invention relates to the technical field of rock mechanics tests, and particularly relates to a test device and method for non-destructive water immersion and multi-directional deformation monitoring of soft rock. Background Art

[0002] The water-rock interaction is one of the hot and difficult issues in the current research field of engineering rock mechanics. The physical and chemical interactions between water and rock will change the mineral composition and microscopic structure of the rock, affect the mechanical and deformation properties of the rock, and have an ignorable impact on the stability of engineering rock masses such as roadway surrounding rocks and coal pillar dams of underground reservoirs. Among them, soft rock is a rock that is greatly affected by the water-rock interaction and is rich in unstable clay minerals with strong water absorption and strong expansibility, resulting in the characteristics of low bearing capacity and easy softening and disintegration when encountering water. Therefore, carrying out research on the hydration expansion characteristics of soft rock is of great significance for engineering safety. However, traditional rock water immersion test devices usually adopt a direct immersion method, which will cause the soft rock specimen to easily disintegrate and break during the water absorption process. At the same time, it is difficult to accurately collect the mass change and deformation data of the soft rock specimen, especially the expansion characteristics cannot be effectively measured. Therefore, there is an urgent need for a device and method that can continuously monitor the multi-directional deformation and water absorption mass during the water absorption process of the soft rock specimen while ensuring the integrity of the soft rock specimen, and quantitatively analyze its expansion sensitivity, so as to more accurately evaluate the deformation law during the hydration process of the soft rock. Summary of the Invention

[0003] Object of the Invention: Aiming at the above shortcomings, the present invention provides a test device and method for non-destructive water immersion and multi-directional deformation monitoring of soft rock, which can avoid the disintegration and damage of soft rock caused by direct water immersion in the traditional test method, and at the same time, through multi-sensor fusion, realize the real-time and accurate measurement of the water absorption and expansion characteristics of the soft rock specimen from the initial water absorption to the saturation stage.

[0004] Technical Solution: To solve the above problems, the present invention adopts a test device for non-destructive water immersion and multi-directional deformation monitoring of soft rock, including a box body, on which an opening and closing door is hinged, a control panel is arranged on the box body, a refrigeration unit, an electric heating tube, a weighing sensor, a laser sensor, and a temperature and humidity sensor are arranged inside the box body, a fog inlet communicating the inside and outside of the box body is arranged on the box body wall, and an atomizing humidifier is arranged outside the box body, and the atomizing humidifier is connected to the fog inlet through a pipeline; the refrigeration unit and the electric heating tube are used to adjust the temperature inside the box body, the weighing sensor is used to weigh the weight of the soft rock specimen, the laser sensor is used to measure the shape change of the soft rock specimen, and the temperature and humidity sensor is used to measure the temperature and humidity inside the box body; the control panel is electrically connected to the refrigeration unit, the electric heating tube, the weighing sensor, the laser sensor, and the temperature and humidity sensor.

[0005] Further, a water return device is also provided inside the box body. The suction end of the water return device is located at the bottom of the box body and is used to suck the accumulated water in the box body. The atomizing humidifier is connected to the water return device through a pipeline.

[0006] Further, the water return device includes a water pump, a drainage pipeline, and a filtering device. The water pump is connected to the bottom of the box body through the drainage pipeline, and the filtering device is arranged inside the drainage pipeline.

[0007] Further, a detachable water storage tank is provided inside the atomizing humidifier, and the drainage pipeline of the water return device is connected to the detachable water storage tank.

[0008] Further, an anti-condensation device in the form of an inclined deflector plate structure is also provided inside the box body, and the anti-condensation device is arranged at the fog outlet end of the fog inlet.

[0009] Further, the laser sensor includes a top laser sensor and four lateral laser sensors, which are respectively used to measure the shape change conditions above and in the front, rear, left, and right sides of the soft rock specimen. The monitoring accuracy of the laser sensor is better than ±0.01 mm.

[0010] Further, a circulation fan is also provided inside the box body.

[0011] Further, a heat insulation layer is provided on the surface of the box body, and a transparent observation window is provided on the opening and closing door.

[0012] The present invention also provides a test method for the above-mentioned test device for non-destructive immersion and multi-directional deformation monitoring of soft rock, including the following steps:

[0013] Step 1: Pretreat the soft rock specimen and place it on the weighing sensor.

[0014] Step 2: Set the target temperature and humidity on the control panel, adjust the temperature through the refrigeration unit and the electric heating tube, and use the atomizing humidifier to provide atomized moisture into the box body.

[0015] Step 3: Start the laser sensor and the weighing sensor, aim at the top and side of the soft rock specimen, and collect the mass and multi-directional deformation data of the soft rock specimen in real time during the water absorption process.

[0016] Step 4: Receive, process, and analyze the mass and multi-directional deformation data of the soft rock specimen through the control panel, and calculate the moisture content, free swelling rate, and swelling evaluation index of the soft rock specimen in real time. The free swelling rate includes the linear swelling rate and the volume free swelling rate, and the swelling evaluation index includes the mass-based free swelling ratio and the mass-volume ratio.

[0017] Step 5: Analyze the variation laws of the above indexes in different time periods, determine the water absorption stage of the soft rock, and give a prompt on the control panel.

[0018] Further, the pretreatment includes processing the soft rock specimen into a preset shape and drying it to eliminate internal residual moisture.

[0019] Beneficial effects: Compared with the prior art, the remarkable advantages of the present invention are as follows: (1) Through atomized humidification, the water mist is evenly diffused and attached to the surface of the specimen, avoiding the disintegration and damage of the soft rock caused by the direct immersion process, realizing the non-destructive immersion of the soft rock specimen, ensuring the integrity of the soft rock during the test, and facilitating the effective measurement of its swelling characteristics; (2) Through the collaborative work of multi-directional laser sensors and weighing sensors, the real-time and accurate acquisition of the weight and multi-directional swelling deformation data of the soft rock specimen during the water absorption process is realized, and the anisotropic swelling characteristics of the soft rock can be accurately evaluated; (3) Through the cooperation of the anti-condensation device and the water return device to form a water cycle, the condensed water and excess droplets are effectively recovered, filtered and then returned to the water storage tank of the atomizing humidifier, reducing the frequency of manual water replenishment, improving the water resource utilization rate and the continuous operation time of the device; (4) When processing data, evaluation indexes such as the mass-based free swelling ratio and the mass-volume ratio are introduced, and the swelling sensitivity at different stages is quantified in combination with real-time data, which is applicable to various soft rock engineering such as roadways and slopes, and provides a scientific basis for the support and protection design of surrounding rocks. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the overall structure of the test device of the present invention;

[0021] Figure 2 It is a side view of the test device of the present invention;

[0022] Figure 3 It is a flow chart of the test method for the soft rock specimen of the present invention;

[0023] Figure 4 It is a moisture content-time curve graph of the soft rock of the present invention;

[0024] Figure 5 It is a swelling rate-time curve graph of the soft rock of the present invention;

[0025] Figure 6 It is a mass-based free swelling ratio curve graph of the soft rock of the present invention. Detailed Embodiments

[0026] As Figure 1 and Figure 2As shown in the figure, a test device for non-destructive water immersion and multi-directional deformation monitoring of soft rock in this embodiment includes a box body 1. A heat preservation layer is provided outside the box body 1, which can effectively block the influence of temperature fluctuations in the external environment, further improve the constant temperature and humidity accuracy inside the box body, and meet the strict requirements of the environment for long-term continuous tests. A hinged opening and closing door 3 is provided on the box body 1, and a transparent observation window is provided on the opening and closing door 3, which is convenient for specimen loading, equipment maintenance and real-time observation of the internal state of the box, effectively improving the monitoring efficiency and timely discovering and handling abnormal situations. A control panel 4 is provided on the front of the upper part of the box body 1. Inside the box body 1, there are a refrigeration unit 5, an electric heating tube 6, a circulation fan 7, a water return device 9, a weighing sensor 10, a laser sensor 12 and a temperature and humidity sensor 13.

[0027] The refrigeration unit 5 and the electric heating tube 6 are used to adjust the temperature inside the box body 1, so that the inside of the box body can switch between two modes of cooling and heating. The circulation fan 7 is used to make the air inside the box body flow evenly and avoid too large local temperature gradient. At the same time, during the humidification or dehumidification process, the water vapor can be evenly diffused inside the box. The temperature and humidity control system composed of the refrigeration unit 5, the electric heating tube 6 and the internal circulation fan 7 can stably maintain the preset environment for a long time and reduce the influence of other factors during the water absorption process.

[0028] The weighing sensor 10 is used to weigh the weight of the soft rock specimen 11. During the water absorption process of the soft rock, the change of the specimen weight can be measured in real time; through the relationship between the weighing data and time, the dynamic moisture content curve of the soft rock can be calculated, which is convenient for studying the water absorption characteristics of the soft rock under the interaction of water and rock.

[0029] The laser sensor 12 is used to measure the shape change of the soft rock specimen 11. Specifically, a top laser sensor and four lateral laser sensors are arranged inside the box body 1, which are used to measure the shape changes above and in the front, back, left and right sides of the soft rock specimen 11 respectively, collect the swelling amounts of the specimen at different angles, and thus obtain complete multi-directional free swelling rate information. The monitoring accuracy of the laser sensor 12 is better than ±0.01 mm. Due to the non-contact measurement method, it can avoid local disturbances caused by touching the surface of the specimen.

[0030] The temperature and humidity sensor 13 is used to measure the temperature and humidity inside the box body 1.

[0031] The control panel 4 is electrically connected to the refrigeration unit 5, the electric heating tube 6, the weighing sensor 10, the laser sensor 12 and the temperature and humidity sensor 13 to realize real-time monitoring and adjustment of the temperature and humidity inside the box, the mass and deformation of the specimen, and ensure the stable progress of the test.

[0032] On the wall of the box body 1, there is a fog inlet 8 that connects the inside and outside of the box body. An atomizing humidifier 14 is provided outside the box body 1, and the atomizing humidifier 14 is connected to the fog inlet 8 through a pipeline. The water return device 9 includes a water pump, a drainage pipeline, and a filtering device. The water pump is connected to the bottom of the box body through the drainage pipeline, and the filtering device is arranged in the drainage pipeline. The atomizing humidifier 14 is provided with a detachable water storage tank, and the drainage pipeline of the water return device 9 is connected to the detachable water storage tank. The solution components in the water storage tank can be replaced to simulate complex engineering conditions such as groundwater chemical erosion and saline environment, and expand the applicability of the test scenario.

[0033] Inside the box body 1, there is also an anti-condensation device 2 in the structure of an inclined deflector plate. The anti-condensation device 2 is arranged at the fog outlet end of the fog inlet 8 to prevent the condensed water droplets from directly dripping onto the surface of the soft rock specimen 11, prevent the local disintegration and damage of the rock specimen caused by the impact of the water droplets, and guide the condensed water flow towards the bottom of the box body 1. After the water vapor ejected from the fog inlet 8 is condensed, it flows along the anti-condensation device 2 towards the bottom of the box body 1, and the accumulated water is pumped out by the water pump of the water return device 9 and enters the water storage tank of the atomizing humidifier 14 after filtration, realizing the recycling of the excess water.

[0034] As Figure 3 shown, the test method of the above test device for non-destructive immersion and multi-directional deformation monitoring of soft rock includes the following steps:

[0035] Step 1: Pretreat the soft rock specimen 11 and place it on the weighing sensor 10. First, select a suitable soft rock specimen, measure its initial height H0 and initial diameter D0. In this example, the soft rock specimen is taken from the in-situ rock mass on site and prepared into a cylindrical specimen with a diameter of 50 mm and a height of 100 mm, and the height-diameter ratio is 2. Put the soft rock specimen 11 into the oven, set a constant temperature (such as 105 °C), and dry it continuously for 24 hours to eliminate the internal residual moisture and maintain the test consistency. Then place it in the dryer to cool to room temperature for subsequent operations. After the drying treatment, place the soft rock specimen 11 on the weighing sensor 10 inside the box body 1 to measure and record the initial mass m0 of the rock specimen.

[0036] Step 2: Set the temperature and humidity inside the box body 1 to 20 °C and 99% respectively. Start the refrigeration unit 5 and the electric heating tube 6 to quickly reach and maintain this temperature and humidity inside the box body 1. The atomizing humidifier 14 uniformly injects atomized water into the box body 1 through the fog inlet 8. The anti-condensation device 2 at the top of the box body 1 can drain the condensed water to the side wall through the inclined deflector plate structure and flow to the micro water pump and the drainage / water return device at the bottom, preventing the water droplets from directly dripping onto the specimen surface and causing disintegration; if there is excess water, it will be filtered and returned to the water storage tank of the atomizing humidifier to realize the recycling of water.

[0037] Step 3: Start the laser sensor 12 and the weighing sensor 10, align them with the top and sides of the soft rock specimen 11, and collect the mass and multi-directional deformation data of the soft rock specimen 11 during the water absorption process in real time.

[0038] For the convenience of calculating the linear expansion rate, the initial displacements corresponding to these five directions are defined as zero:

[0039] x h (0) = 0, x1(0) = 0, x2(0) = 0, x3(0) = 0, x4(0) = 0,

[0040] where x h (t) represents the displacement of the vertical direction (measured by the top probe) relative to the initial position; x1(t) to x4(t) represent the displacement amounts in the four lateral directions respectively. Combining with m(t) recorded by the weighing sensor, the mass change of the specimen during water absorption and the multi-directional linear deformation data can be obtained in real time. Through the control panel 4, these data can be continuously recorded and analyzed during the entire water absorption process.

[0041] Step 4: Receive, process, and analyze the mass and multi-directional deformation data of the soft rock specimen 11 through the control panel 4, and calculate the water content, free swelling rate, and swelling evaluation index in real time. The free swelling rate includes the linear swelling rate and the volume free swelling rate, and the swelling evaluation index includes the mass-based free swelling ratio and the mass-volume ratio.

[0042] Calculation formula for water content ω(t):

[0043]

[0044] In the formula, m0 and m(t) are the initial mass of the rock specimen and the mass recorded by the weighing sensor at time t respectively.

[0045] Calculation formula for linear swelling rate δ i (t):

[0046]

[0047] In the formula, X i (t) is the displacement amount in this direction, and L i0 is the initial dimension in this direction (height H0 and radius R0).

[0048] Calculation formula for volume free swelling rate δ v (t):

[0049]

[0050] In the formula, V(t) is the volume of the specimen at time t, which can be calculated according to the average displacement amount in each direction, and V0 is the initial volume of the specimen.

[0051] Calculation formula for mass-based free swelling ratio (MSR):

[0052]

[0053] In the formula, the mass-based free swelling ratio MSR(t) represents the degree of swelling caused by unit water absorption, coupling the water content increase and swelling rate of the rock sample, and can be used to evaluate the water swelling sensitivity of different rock samples or the same rock sample under different environments, and predict the volume deformation degree caused by the water-rock interaction in highly swelling rock strata.

[0054] Calculation formula for mass-volume ratio (VMR):

[0055]

[0056] In the formula, the mass-volume ratio VMR(t) is the volume increment (cm 3 / g) brought by unit mass increment.

[0057] Step Five: Analyze the variation laws of the above indicators in different time periods, determine the water absorption stage of the soft rock, and give a prompt on the control panel 4. Set in the control panel 4 to record the readings every 1 minute within 48 hours before the test. When 48 hours later, the difference between the mass readings for three consecutive times is not greater than 0.1 g or the difference in deformation data is not greater than 0.01 mm, it indicates that the water absorption and swelling of the rock have ended. During the water absorption process, if the swelling rate δ i (t) in a certain direction shows a significant increase, it indicates that the mineral structure or fissures in this direction are more sensitive to water; if the mass-based free swelling ratio (MSR) or mass-volume ratio (VMR) rapidly increases in a certain stage, then this stage can be determined as the swelling sensitive period. The operator can view the real-time deformation curves in each direction and the overall volume swelling curve through the display interface, such as Figures 4 - 6 , and combine with the preset threshold or analysis model to evaluate the dynamic response of the soft rock to hydration. For the specimens that enter the stable period later, their subsequent creep or stable behavior can also be continuously observed for a long time, providing a reference for the analysis of the surrounding rock safety in the long-term water environment in engineering.

[0058] In summary, through atomization humidification, the water mist is evenly diffused and attached to the surface of the specimen, avoiding the disintegration and damage of soft rock caused by the direct immersion process, realizing the non-destructive immersion of soft rock specimens, ensuring the integrity of soft rock during the test, and facilitating the effective measurement of its swelling characteristics. Through the collaborative work of multi-directional laser sensors and weighing sensors, the real-time and accurate acquisition of the weight and multi-directional swelling deformation data of soft rock specimens during the water absorption process is achieved, and the anisotropic swelling characteristics of soft rock can be accurately evaluated. Through the cooperation of the anti-condensation device and the return water device to form a water cycle, the condensed water and excess droplets are effectively recovered, filtered and then returned to the water storage tank of the atomizing humidifier, reducing the frequency of manual water replenishment, improving the water resource utilization rate and the continuous operation time of the device. When processing data, evaluation indicators such as mass-based free swelling ratio and mass-volume ratio are introduced, and the swelling sensitivity at different stages is quantified in combination with real-time data, which is applicable to various soft rock engineering such as roadways and slopes, and provides a scientific basis for the support and protection design of surrounding rocks.

Claims

1. A test device for non-destructive immersion and multi-directional deformation monitoring of soft rock, characterized in that, It includes a box body (1), on which an opening and closing door (3) is hinged. A control panel (4) is provided on the box body (1). A refrigeration unit (5), an electric heating tube (6), a weighing sensor (10), a laser sensor (12), and a temperature and humidity sensor (13) are provided inside the box body (1). An atomizing inlet (8) communicating the inside and outside of the box body is provided on the wall surface of the box body (1). An atomizing humidifier (14) is provided outside the box body (1), and the atomizing humidifier (14) is connected to the atomizing inlet (8) through a pipeline; the refrigeration unit (5) and the electric heating tube (6) are used to adjust the temperature inside the box body (1), the weighing sensor (10) is used to weigh the soft rock specimen (11), the laser sensor (12) is used to measure the shape change of the soft rock specimen (11), and the temperature and humidity sensor (13) is used to measure the temperature and humidity inside the box body (1); the control panel (4) is electrically connected to the refrigeration unit (5), the electric heating tube (6), the weighing sensor (10), the laser sensor (12), and the temperature and humidity sensor (13).

2. The test device for non-destructive immersion in water and multi-directional deformation monitoring of soft rock according to claim 1, characterized in that, A water return device (9) is also provided inside the box body (1). The water absorption end of the water return device (9) is located at the bottom of the box body (1) and is used to absorb the accumulated water inside the box body (1). The atomizing humidifier (14) is connected to the water return device (9) through a pipeline.

3. The test device for non-destructive immersion and multi-directional deformation monitoring of soft rock according to claim 2, characterized in that, The water return device (9) includes a water pump, a drainage pipeline, and a filtering device. The water pump is connected to the bottom of the box body through the drainage pipeline, and the filtering device is arranged inside the drainage pipeline.

4. The test device for non-destructive immersion in water and multi-directional deformation monitoring of soft rock according to claim 3, wherein, A detachable water storage tank is provided inside the atomizing humidifier (14), and the drainage pipeline of the water return device (9) is connected to the detachable water storage tank.

5. The test device for non-destructive immersion in water and multi-directional deformation monitoring of soft rock according to claim 1, wherein, An anti-condensation device (2) in the form of an inclined diversion plate structure is also provided inside the box body (1), and the anti-condensation device (2) is arranged at the fog outlet end of the atomizing inlet (8).

6. The test device for non-destructive immersion in water and multi-directional deformation monitoring of soft rock according to claim 1, characterized in that, The laser sensor (12) includes a top laser sensor and four lateral laser sensors, which are respectively used to measure the shape change of the soft rock specimen (11) above and in the front, rear, left, and right directions. The monitoring accuracy of the laser sensor (12) is better than ±0.01 mm.

7. The test device for non-destructive immersion in water and multi-directional deformation monitoring of soft rock according to claim 1, characterized in that A circulation fan (7) is also provided inside the box body (1).

8. The test device for non-destructive immersion in water and multi-directional deformation monitoring of soft rock according to claim 1, wherein A heat preservation layer is provided on the surface of the box body (1), and a transparent observation window is provided on the opening and closing door (3).

9. A testing method for the testing device for non-destructive immersion and multi-directional deformation monitoring of soft rock according to any one of claims 1-8, characterized in that, It includes the following steps: Step 1: Pretreat the soft rock specimen (11) and place it on the weighing sensor (10). Step 2: Set the target temperature and humidity on the control panel (4), regulate the temperature through the refrigeration unit (5) and the electric heating tube (6), and use the atomizing humidifier (14) to provide atomized moisture into the box body (1). Step 3: Start the laser sensor (12) and the weighing sensor (10), aim at the top and sides of the soft rock specimen (11), and collect the mass and multi-directional deformation data of the soft rock specimen (11) during the water absorption process in real time. Step 4: Receive, process, and analyze the quality and multi-directional deformation data of the soft rock specimen (11) through the control panel (4), and calculate in real time the moisture content, free swelling ratio, and swelling evaluation index of the soft rock specimen (11). The free swelling ratio includes the linear swelling ratio and the volume free swelling ratio, and the swelling evaluation index includes the mass-based free swelling ratio and the mass-volume ratio; Step 5: Analyze the variation laws of the above indicators in different time periods, determine the water absorption stage of the soft rock, and give a prompt on the control panel (4).

10. The test method according to claim 9, wherein The pre-treatment includes processing the soft rock specimen (11) into a preset shape and drying it to eliminate the internal residual moisture.

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