CN211856179U - Rock mass contains frozen swelling expansion process monitoring test system of ice crack network - Google Patents
Rock mass contains frozen swelling expansion process monitoring test system of ice crack network Download PDFInfo
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- CN211856179U CN211856179U CN202020177632.6U CN202020177632U CN211856179U CN 211856179 U CN211856179 U CN 211856179U CN 202020177632 U CN202020177632 U CN 202020177632U CN 211856179 U CN211856179 U CN 211856179U
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Abstract
The utility model provides a rock mass contains frozen swelling expansion process monitoring test system of ice crack network belongs to ground mechanics technical field. The system comprises a true triaxial loading device, a temperature control acquisition system, a frost heaving force acquisition control system and an acoustic emission acquisition system. The true triaxial loading device is positioned in the freeze thawing environment box body and is fixed by the self-locking device. The temperature control acquisition system is positioned on the right side of the freezing and thawing environment box body, and the whole temperature system is monitored by a temperature sensor in the box body. The frost heaving force acquisition control system converts signals received by the pressure sensor into electric signals through a frost heaving force measuring sensor arranged in a rock test piece crack, and transmits the electric signals to the computer terminal for analysis. The acoustic emission acquisition system collects acoustic signals of rock mass fracture through the acoustic emission probe and transmits the acoustic signals to the terminal control system. The utility model discloses can reflect the ice crack's in the low temperature rock mass extension process and the damage condition fast and accurately, fix a position the rock mass range of rupture accurately, provide the reference for cold district rock mass engineering construction.
Description
Technical Field
The utility model relates to a ground mechanics technical field especially indicates a rock mass contains frozen swelling expansion process monitoring test system of ice crack network.
Background
Freeze-thaw damage and destruction of low-temperature fractured rock masses are always key scientific problems in engineering construction of rock masses in cold regions. The construction of rock mass engineering in cold regions, low-temperature storage of underground liquefied gas, protection of historic building cultural relics and the like all relate to the problem of freeze-thaw damage of rock masses, and for fractured rock masses, the temperature stress under freeze-thaw cycles and the frost heaving force generated by water-ice phase transition repeatedly stretch fracture tips to cause fracture expansion and penetration, so that surrounding rock fracture is caused, and great threat is formed to the stability of low-temperature underground engineering. Under the action of freeze-thaw cycle, the water-containing cracks in the rock body can be subjected to initiation, development and dissipation of frost heaving force, crack frost heaving expansion and rock body freeze-thaw damage degree are also controlled by the frost heaving force, and for saturated low-permeability rock bodies, larger frost heaving force can be generated in the cracks. The freeze-thaw damage and fracture of fractured rock mass are mainly the result of fracture frost heaving expansion evolution caused by fracture frost heaving force.
The main factors inducing the frost damage of the rock body are the frost heaving effect generated by the moisture in the crack under the low-temperature environment on one hand, and the frost heaving process of the crack can be limited by external load because the engineering rock body is in the ground stress environment on the other hand, so that the evolution process and the magnitude of the frost heaving force of the crack are directly influenced. A large number of geological structural surfaces which are randomly and discontinuously distributed exist in fractured rock mass, such as joints, faults and the like, the structural weak surfaces with different development degrees cause the fractured rock mass to have obvious anisotropic characteristics, part of the structural surfaces are greatly influenced by frost heaving effect, even the expansion and evolution of cracks are accelerated to cause the rock mass to be rapidly damaged, the research on various structural surfaces in the rock mass at home and abroad is more, but the research on the frost heaving process of the ice cracks is lacked, and how to prevent the rock mass from being damaged and destroyed due to the frost heaving expansion of the ice cracks is worth deep thinking. Therefore, the method has important significance for effectively monitoring the frost heaving and expanding process of the ice cracks.
The true triaxial loading test device simulates the stress state borne by any small unit in the rock-soil body under the condition that the rock-soil body is subjected to load. There are two loading modes for a typical true triaxial test: rigid loading in three directions, rigid loading in two directions and flexible loading in one direction. The sample is generally cubic. In the test, the samples were subjected to stresses on the principal stress surfaces perpendicular to each other, that is, the samples were subjected to three principal stresses σ 1, σ 2, and σ 3 independently on three mutually perpendicular surfaces, and the corresponding principal strains 1, 2, and 3, the volume change, and the like were measured. Compared with the conventional triaxial test, namely the axisymmetric triaxial test, the result measured by the true triaxial test method can reflect the real constitutive relation more and is more complex.
The acoustic emission is abbreviated as AE and refers to a general physical phenomenon that strain energy is rapidly released to generate transient stress waves under the stress action of a material due to crack propagation, plastic deformation or phase change, and acoustic emission signals are generated by almost all rock materials during plastic deformation and fracture failure. The intensity of acoustic emission signals generated by the rock material under the action of external force is very weak, so that human ears cannot be directly captured, and the monitoring can be realized only by means of a sensitive electronic instrument. The acoustic emission detection technology is used for researching and deducing materials by detecting and analyzing received acoustic emission signals and dynamically evaluating the integrity of a structure. Compared with other nondestructive detection methods, the acoustic emission detection technology is an unconventional dynamic real-time nondestructive detection method, and can continuously monitor the internal damage and deformation of the rock body in the whole process of damage due to the unique real-time and dynamic detection performance, and the damage failure of the rock is actually the process from the initiation and the expansion of an internal crack to the formation of a macroscopic crack damage. Therefore, there is a necessary link between the destruction of rock mass by frost heaving and the acoustic emission phenomena of the rock. However, most of the existing experimental researches on the triaxial compression acoustic emission characteristics of the rock mainly aim at the uniaxial acoustic emission characteristic rules and the conventional triaxial acoustic emission characteristic rules, and relatively few research results relate to the acoustic emission characteristic rules in the rock failure process under the condition of true triaxial.
Therefore, the utility model discloses an utilize real triaxial loading test system and corresponding test method of acoustic emission system monitoring rock mass frost crack frost heave expansion process, including real triaxial loading system, temperature control system, acoustic emission collection system and frost heave force acquisition control system for when surveying low temperature crack rock mass frost heave damage and destruction under different temperature and different freeze-thaw cycle condition, the expansion situation of the inside ice crack of rock mass. The acoustic emission can accurately position the change range and the fracture information of the rock mass fracture, improves the accuracy of the reconstructed image of the rock in the fracture process under the frost heaving effect, and better reveals the fracture evolution process of the low-temperature fractured rock mass under different conditions.
The patent of the invention comprises the following comparison: a rock fracture frost heaving force testing device under the action of vertical load. The patent application No. 201711009776.X, application publication No. CN 107631940 a. The patent is based on that most of research methods of fracture frost heaving force under the action of the current vertical load are numerical simulation and theoretical models, data support is lacked, and a frost heaving force testing device in fractures with different geometric shapes under the action of the vertical load is provided. The device relates to the technical field of rock mechanics tests, and comprises a heat-insulating bearing base, two drawer-type side wall steel frames, two vertical pressurizing steel plates, a hydraulic jack and two H-shaped empty groove steel supports. The area between the vertical pressurizing steel plate and the adjacent steel plate is a freezing area, a heat insulation cover is covered above the freezing area, a cold air conveying pipe is arranged on the heat insulation cover, a rock block is arranged in the freezing area, a vertical crack is formed in the rock block, and a sheet-shaped pressure sensor and a needle-shaped temperature sensor are arranged at the crack. Before testing, cutting cracks required by the test in a processed cubic rock block, inserting two prefabricated steel plates into the cracks, determining the positions and the number of mounting wire outlet holes according to the test requirements, chiseling the mounting wire outlet holes in the direction perpendicular to the cracks, placing a sheet-shaped pressure sensor and a needle-shaped temperature sensor in the mounting wire outlet holes, ensuring that the sheet-shaped pressure sensor and the needle-shaped temperature sensor are flush with the inner walls of the cracks, injecting cement mortar into the mounting wire outlet holes, placing the mounting wire outlet holes in a constant-temperature constant-humidity maintenance pool, and waiting for the cement mortar to solidify; then the prefabricated steel plate is drawn out, and the two sides of the crack are sealed by waterproof adhesive tapes and cement mortar. In the test, a rock block is placed, purified water is injected into the crack, the vertical pressurizing steel plate is adjusted to just contact with one side surface of the rock block, then the hydraulic jack is controlled to pressurize, and the crack water in the rock block is cooled through the cold air conveying pipe.
By contrast, we found that:
1. the device that the above-mentioned invention patent used is too simple, and the purport of inventing is the measurement rock crack frozen-expansion force, and the inventor is in this aspect of test process and data processing said very little, the utility model discloses change on original true triaxial test loading device, can accurately measure the frozen-expansion force when rock breaks under low temperature environment, can also monitor the frozen-expansion process of rock under low temperature environment, finally handle gained data through computer terminal system, the process is comparatively complete, and the experiment is comparatively rigorous.
2. The device has only measured rock crack frozen swelling power under the vertical load effect, and has neglected the frozen swelling effect of other external load rocks under triaxial pressure promptly, the utility model discloses with a true triaxial loading device has simulated the actual stress environment of low temperature crack rock mass, can regulate and control the triaxial pressure of rock at any time through three hand pump, it is comparatively reasonable.
3. The low temperature environment of above-mentioned device encloses synthetic freezing district through each part, relies on the freezing conveyer pipe input air conditioning of upper portion again, and the regulation and control of temperature is comparatively difficult and lack the control, can't guarantee sufficient low temperature environment, the utility model discloses a freezing district is made to freezing and thawing environment box, and the space seals and easily controls, and the temperature in the box is controlled through external connection's temperature acquisition controller, monitors through the inside temperature sensor of box, and the design is comparatively reasonable, and gained data is also more accurate.
4. Above-mentioned device relies on the frozen expansive force in the rock mass crack of installation pressure sensor measurement crack, and the great and unable accurate positioning frozen expansive force source of experimental data error, and the utility model discloses install frozen expansive force measurement sensor in the rock, the extension in multichannel simultaneous monitoring rock mass crack has enlarged the scope of frozen expansive force monitoring, can also predict frozen expansive evolution process, and experimental precision is higher.
5. The device can not give the frozen swelling power acquisition control system, lacks the description to later stage data processing, the utility model discloses there are temperature control acquisition system, acoustic emission collector, frozen swelling power acquisition controller and a computer terminal equipment at the external connection of loading device part to finally explain holistic experimental method, explained whole experimental operation control system well, the process is comparatively complete, and it is comparatively clear and definite to implement.
SUMMERY OF THE UTILITY MODEL
The utility model discloses a cold district rock mass freeze thawing unstability prediction provides the foundation, perfect more and to cold district engineering rock mass the monitoring of the expansion evolution process of inside ice crack under the frost heaving effect, effectual prevention rock mass leads to the rock mass to damage because of the frost heaving expansion of ice crack destroys, a rock mass contains ice crack network frost heaving expansion process monitoring test system is provided, can simulate the stress environment of cold district rock mass comparatively accurately, and monitor the rock mass frost heaving information of breaking under the freeze thawing circulation of difference and freezing temperature, the prediction rock mass condition of breaking.
The system comprises a true triaxial loading device, a temperature control acquisition system, a frost heaving force acquisition control system and an acoustic emission acquisition system, wherein the true triaxial loading device is positioned inside a freezing and thawing environment box body and is fixed by a self-locking device, the temperature control acquisition system is positioned on the right side of the freezing and thawing environment box body, the whole temperature system is monitored by a temperature sensor in the freezing and thawing environment box body, the frost heaving force acquisition control system is used for converting a signal into an electric signal to be transmitted to a computer terminal for analysis, and the acoustic emission acquisition system is used for collecting a sound signal generated by rock mass fracture and transmitting the sound signal to a computer through an acoustic emission probe.
The real triaxial loading device comprises a cable, a four-claw connecting mechanism, a loading device top plate, a loading device side plate, a pin, an acoustic emission probe, a loading device bottom plate, a hand pump and a hand pump rod, wherein the loading device top plate, the loading device side plate and the loading device bottom plate form a closed loading space, the acoustic emission probe is arranged in the loading space, each panel of the loading device is connected with the four-claw connecting mechanism through the pin, the cable is connected with each control acquisition system, the three hand pumps are respectively connected with the four-claw connecting mechanism in three directions, and the hand pump rod is arranged on the hand pump.
The side face of the freezing and thawing environment box body is provided with a visual heat preservation window, the front face of the freezing and thawing environment box body is provided with an environment box body left door and an environment box body right door, the side face of the freezing and thawing environment box body is provided with a hole for penetrating a cable, a hole opening part is provided with a plug, a temperature sensor is arranged inside the side face of the freezing and thawing environment box body, and the temperature sensor is connected with.
The temperature control acquisition system, the frost heaving force acquisition control system and the sound emission acquisition system are connected with a computer.
A groove is arranged on the side plate of the loading device, and an acoustic emission probe is arranged in the groove.
The top plate of the loading device is embedded with a water replenishing pipe.
The method for applying the system comprises the following steps:
s1: preparation of the test: preparing natural rock blocks with joint cracks or artificially prefabricated crack rock blocks, and manually cutting the natural rock blocks or the artificially prefabricated crack rock blocks into cubes with proper sizes;
s2: water saturation: saturating the test piece with water, and sleeving a black rubber mold on the rock block before the test piece is saturated with water to prevent water from leaking out until the rock block reaches a water saturation state;
s3: installing a frost heaving force measuring sensor: mounting a frost heaving force measuring sensor in the rock test piece crack;
s4: placing the water-saturated rock blocks on a loading device bottom plate, closing a loading device side plate and a loading device top plate to form a closed loading space, and then placing the whole device in a freeze-thaw environment box body to be connected with a four-claw connecting mechanism through pins to form a self-locking device;
s5: an anti-freezing acoustic emission probe is arranged in a small hole of a side plate of the loading device outside the loading device;
s6: connecting all the measuring sensors to the corresponding acquisition devices through cables;
s7: pressurizing by a hand pump: pressurizing the loading device to a designed value by using a hand pump;
s8: cooling and replenishing water: gradually cooling the freezing and thawing environment box body to a preset temperature through an external temperature control system, and simultaneously replenishing water to the rock mass through a water replenishing pipe in a top plate of the loading device until water in the rock mass is frozen;
s9: record experimental data: recording acoustic emission and frost heaving force information in the icing process of the rock mass, and fitting a stress-strain image in a computer;
s10: dismounting device: the connection between the cable and the sensor is released, the four-claw connecting mechanism is opened, and the cubic loading sleeve is detached;
s11: the test was repeated: changing the rock block, respectively setting different preset stress and preset temperature, repeating the test process to obtain a plurality of groups of data for comparison;
s12: and (5) sorting the data to obtain a conclusion.
The utility model discloses an above-mentioned technical scheme's beneficial effect as follows:
1. the true triaxial test and the acoustic emission technology can quickly and accurately reflect the expansion process and damage condition of ice cracks in low-temperature rock masses, accurately position the rock mass fracture range, and effectively prevent the damage and damage of fractured rock masses under the action of low-temperature frost heaving by analyzing the multi-freeze-thaw cycle action and the fracture information of rock masses under different low temperatures through the test, thereby providing reference for the engineering construction of rock masses in cold regions.
2. The utility model adopts the self-locking system, the loading is more convenient, the loading speed can be controlled manually, the stress can be changed, the test process is more accurate, simple and convenient;
3. the utility model discloses test system is simple and convenient, easily installs, and high mechanization, experimental method science is rigorous, the operation of being convenient for.
Drawings
FIG. 1 is a schematic view of the overall structure of the network frost heaving expansion process monitoring test system for the ice-containing cracks in the rock mass;
FIG. 2 is a schematic structural view of a true triaxial loading device of the rock mass ice crack containing network frost heaving expansion process monitoring test system of the utility model;
FIG. 3 is a schematic structural view of a freezing and thawing environment box body of the network frost heaving expansion process monitoring test system for rock mass containing ice cracks of the utility model;
FIG. 4 is a schematic structural view of a four-jaw connecting mechanism of the network frost heaving expansion process monitoring test system for the ice crack contained in the rock mass of the utility model;
FIG. 5 is a schematic structural view of a side plate of a loading device of the network frost heaving expansion process monitoring test system for ice cracks in rock mass;
FIG. 6 is a schematic diagram of the structure of the top plate of the loading device of the network frost heaving expansion process monitoring test system for the rock mass containing ice cracks;
fig. 7 is the utility model discloses a rock mass contains frozen swelling expansion process monitoring test system's of ice crack network loading device bottom plate structure sketch map.
Wherein: 1-freezing and thawing environment box body; 2-a cable; 3-a four-claw connecting mechanism; 4-loading the device top plate; 5-loading device side plate; 6-visual heat preservation window; 7-left door of the environmental box; 8-pin; 9-acoustic emission probe; 10-a loading device base plate; 11-hand pump; 12-hand pump rod; 13-plug; 14-environmental enclosure right door; 15-a temperature sensor; 16-a temperature control acquisition system; 17-a computer; 18-a table; 19-a frost heaving force acquisition control system; 20-an acoustic emission acquisition system; 21-groove; 22-water replenishing pipe.
Detailed Description
In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following detailed description will be given with reference to the accompanying drawings and specific embodiments.
The utility model provides a rock mass contains frozen swelling expansion process monitoring test system of ice crack network.
As shown in figure 1, the system comprises a true triaxial loading device, a temperature control acquisition system 16, a frost heaving force acquisition control system 19 and an acoustic emission acquisition system 20, wherein the true triaxial loading device is positioned inside a freeze-thaw environment box body 1 and is fixed by a self-locking device, the temperature control acquisition system is positioned on the right side of the freeze-thaw environment box body 1, the whole temperature system is monitored by a temperature sensor 15 in the freeze-thaw environment box body 1, the frost heaving force acquisition control system 19 converts signals into electric signals through a frost heaving force measurement sensor arranged in a crack of a rock test piece and transmits the electric signals to a computer 17 terminal for analysis, and the acoustic emission acquisition system 20 collects acoustic signals of rock body cracking through an acoustic emission probe 9 and transmits the acoustic signals to.
As shown in fig. 2, the true triaxial loading device includes a cable 2, a four-jaw connection mechanism 3, a loading device top plate 4, a loading device side plate 5, a pin 8, an acoustic emission probe 9, a loading device bottom plate 10, a hand pump 11 and a hand pump rod 12, the loading device top plate 4, the loading device side plate 5 and the loading device bottom plate 10 form a closed loading space, the acoustic emission probe 9 is arranged in the loading space, as shown in fig. 4, the four-jaw connection mechanism 3 is arranged above the loading device top plate 4, the cable 2 is connected with the true triaxial loading device and a temperature control acquisition system 16, the loading device bottom plate 10 is connected with the four-jaw connection mechanism 3 through the pin 8, as shown in fig. 7, the loading device bottom plate 10 is connected with the hand pump 11, and the hand pump rod 12 is arranged on the hand.
As shown in fig. 3, a visual heat preservation window 6 is arranged on the side surface of the freeze-thaw environment box body 1, a left environmental box body door 7 and a right environmental box body door 14 are arranged on the front surface of the freeze-thaw environment box body 1, a cable penetrates through the opening in the side surface of the freeze-thaw environment box body 1, a plug 13 is arranged at the opening, a temperature sensor 15 is arranged inside the side surface of the freeze-thaw environment box body 1, and the temperature sensor is connected with a temperature.
As shown in fig. 5, the loading device side plate 5 is provided with a groove 21, and the acoustic emission probe 9 is provided in the groove 21.
As shown in fig. 6, a water replenishing pipe 22 is inserted into the top plate 4 of the loading device.
In specific design, the size in confined loading space is 300mm, loading device relies on three hand pumps in the box to provide pressure for the test piece through cable junction four-jaw coupling mechanism, temperature control collection system is located the box right side for make low temperature freeze thawing environment for the box, whole temperature system relies on the temperature sensor in the box to monitor, air conditioning passes through the air conditioning conveyer pipe and provides, visual heat preservation window is all settled to the box both sides, can be used to observe freeze thawing environment in the box. The frost heaving force acquisition control system is connected with an external control system through a frost heaving force measuring sensor arranged in a rock test piece crack, and converts signals received by the pressure sensor into electric signals and transmits the electric signals to the computer terminal for analysis. The acoustic emission acquisition control system collects acoustic signals of rock mass fracture through an acoustic emission probe on the loading device, and then the acoustic signals are connected with an external acoustic emission acquisition controller through a cable and converted into electric signals to be transmitted to the terminal control system. The acoustic emission probe is installed in a small hole in the loading base plate. The loading base plate is positioned in the side plate, the acoustic emission mounting hole is a 2-by-4 channel, and the loading plate is provided with a groove for placing a cable. The acoustic emission probe and the entire loading device are all antifreeze for testing.
The acoustic emission monitoring system is used for analyzing acoustic emission activities of the low-temperature fractured rock mass in the whole damage and damage process under the true triaxial compression condition, and acoustic emission characteristics of the rock under different conditions are discussed by analyzing acoustic emission signals corresponding to different stages of rock frost-swell damage. And then, by analyzing acoustic emission data recorded in the test, drawing a fitting graph of each acoustic emission parameter and stress and strain, and discussing the acoustic emission characteristics of the rock under the true triaxial condition to reveal rock failure precursor characteristics under the true triaxial loading condition and master the process of fracture information and crack propagation.
The frost heaving force monitoring system has the advantages that the frost heaving force monitoring range is a plurality of channels, and changes of a plurality of cracks in a rock body can be monitored simultaneously, so that the expansion evolution of an ice crack network is predicted.
True triaxial loading test system, true triaxial loading device adopted the self-locking system, roof, bottom plate and curb plate each other the gomphosis are a cube device, inside is used for placing the rock test piece, the curb plate is as the loading backing plate of acoustic emission for install the acoustic emission probe and place the cable conductor, it is fixed through the pin joint between four-jaw coupling mechanism and each board, loading device passes through three hand pump and connects four-jaw coupling mechanism around controlling respectively, control, pressure from top to bottom, triaxial pressure can artificial regulation and control, can more complete simulation cold district rock mass's stress condition.
The method for applying the system comprises the following steps:
s1: preparation of the test: preparing natural rock blocks with joint cracks or artificially prefabricated crack rock blocks, and manually cutting the natural rock blocks or the artificially prefabricated crack rock blocks into cubes with proper sizes;
s2: water saturation: saturating the test piece with water, and sleeving a black rubber mold on the rock block before the test piece is saturated with water to prevent water from leaking out until the rock block reaches a water saturation state;
s3: installing a frost heaving force measuring sensor: mounting a frost heaving force measuring sensor in the rock test piece crack;
s4: placing the water-saturated rock blocks on a loading device bottom plate, closing a loading device side plate and a loading device top plate to form a closed loading space, and then placing the whole device in a freeze-thaw environment box body to be connected with a four-claw connecting mechanism through pins to form a self-locking device;
s5: an anti-freezing acoustic emission probe is arranged in a small hole of a side plate of the loading device outside the loading device;
s6: connecting all the measuring sensors to the corresponding acquisition devices through cables;
s7: pressurizing by a hand pump: pressurizing the loading device to a designed value by using a hand pump;
s8: cooling and replenishing water: gradually cooling the freezing and thawing environment box body to a preset temperature through an external temperature control system, and simultaneously replenishing water to the rock mass through a water replenishing pipe in a top plate of the loading device until water in the rock mass is frozen;
s9: record experimental data: recording acoustic emission and frost heaving force information in the icing process of the rock mass, and fitting a stress-strain image in a computer;
s10: dismounting device: the connection between the cable and the sensor is released, the four-claw connecting mechanism is opened, and the cubic loading sleeve is detached;
s11: the test was repeated: changing the rock block, respectively setting different preset stress and preset temperature, repeating the test process to obtain a plurality of groups of data for comparison;
s12: and (5) sorting the data to obtain a conclusion. In each test, the data obtained by monitoring the acoustic emission and the frost heaving force in the test are recorded, the fitting graph of each parameter of the acoustic emission, stress and strain is drawn, and the process from the temperature reduction of a rock body to the ice formation of water in a rock crack until the rock body is cracked is monitored. After all experiments are finished, the influence of different conditions on the expansion of the rock ice cracks is judged by analyzing the frost heaving fracture change of the rock body under different low-temperature environments, and the frost heaving expansion process of the rock ice cracks under different conditions is discussed.
The frost heaving force measuring sensor is a film pressure sensor, the sensor is calibrated before testing, a force measuring area of the film pressure sensor is sleeved with a film, and a waterproof film is adhered to the surface of a crack by waterproof glue so as to facilitate the film sensor to be pulled out and utilized for multiple times;
the method for the true triaxial loading test has the advantages that the hand pump for applying pressure is controlled by the hand pump rod, and different stresses in three directions of a rock body can be provided.
The true triaxial loading experiment method is characterized in that an acoustic emission probe is installed in a small hole in a loading plate, and a cable connected with the probe is connected with the outside through a groove in the loading plate.
The utility model discloses, utilize freeze thawing environment box 1 simulation low temperature environment, the low temperature environment in the box simulates through the outer temperature control collection system 16 of box and makes. The triaxial stress required by the rock test piece is regulated by three hand pumps 11 in a true triaxial loading device in the box. The self-locking system is adopted in the true triaxial loading device required by the test, a top plate, a bottom plate and side plates of the loading device are mutually embedded into a cubic device, a rock test piece is placed inside the cubic device, the side plates are used as loading base plates for acoustic emission and used for installing an acoustic emission probe and placing a cable, the four-jaw connecting mechanism is fixedly connected with the plates through pins to fix the test piece on the experiment table, and a hand pump is used for connecting the four-jaw connecting mechanism to apply pressure to the test piece. The cracking information generated by the frozen swelling effect inside the rock test piece is transmitted to the acoustic emission acquisition system 20 through the anti-freezing acoustic emission probe in the loading base plate, and then is integrated to the computer 17 for analysis. The frost heaving force information generated by the frost heaving effect in the rock test piece is sensed by a frost heaving force measuring sensor arranged on the surface part, then transmitted to a frost heaving force acquisition control system 19, and then summarized to a computer terminal for analysis. The data of the collector is controlled through the frost heaving force, the change of the frost heaving force in the test piece is observed at any time, and the deformation and the damage of the rock mass are monitored in time. Through the data of the acoustic emission collector, the fracture information and the crack propagation process of the rock block under the frozen expansion effect are recorded, the fracture range of the rock block can be accurately positioned, and the observation of the fracture range is facilitated.
The utility model discloses the system sets up acoustic emission sampling frequency and load, deformation sampling frequency at rock mass test piece surface mounting acoustic emission probe, real-time supervision acoustic emission information in the loading process of true triaxial compression, and system automatic acquisition records load, deformation, acoustic emission energy, count and amplitude isoparametric in the test process, and the change in real-time supervision rock mass crack catches and contains ice crack extension process, location ice crack position information.
The utility model discloses the system is at rock mass crack installation frozen expansive force measuring transducer, and the change of accurate perception rock mass crack frozen expansive force through the evolution process of acquisition controller real-time supervision frozen expansive force predicts the rock position of breaking in advance.
The method using the system is implemented as follows:
s1: test preparation. Preparing a plurality of natural rock blocks with joint cracks or artificially prefabricated crack rock blocks, and manually cutting the natural rock blocks or the artificially prefabricated crack rock blocks into cubes with the sizes of 300mm multiplied by 300 mm;
s2: the rock mass is saturated with water. Sleeving a black rubber mold on the rock before water saturation to ensure that water does not leak outwards until the rock is in a water-saturated state;
s3: and (5) an installation stage. Mounting a frost heaving force measuring sensor in a rock test piece crack, wherein the measuring sensor needs to be mounted by a plurality of channels;
s4: placing the water-saturated rock blocks on a loading bottom plate, closing a loading side plate and a top plate to form a closed loading sleeve, and then placing the whole device in a freeze-thaw environment box body to be connected with a four-claw connecting mechanism through pins to form a self-locking device;
s5: an anti-freezing acoustic emission probe is installed in a small hole of a loading base plate on the outer side of the loading device, an acoustic emission probe installation channel is 2-4 channels, each side plate is provided with a plurality of acoustic emission probes, and the acoustic emission probes are used for monitoring simultaneously;
s6: all the measuring sensors are connected to the corresponding acquisition devices through cables, and the cables are connected into the loading devices through grooves in the loading base plates;
s7: and (5) pressurizing by a hand pump. Three hand pump rods are controlled, and the three hand pumps are used for pressurizing the test piece in three directions respectively until the stress of the rock test piece in the three directions reaches an ideal design value;
s8: and (5) cooling and replenishing water. Gradually cooling the freezing and thawing environment box body to a preset temperature through an external temperature control system, monitoring the temperature environment in the box body through a temperature sensor in the box body, stopping when the temperature reaches the preset temperature, and simultaneously replenishing water to the rock test piece through a water replenishing pipe in the loading top plate until water in the rock is frozen;
s9: test data were recorded. Recording acoustic emission and frost heaving force information of the test piece in the icing process, fitting a stress strain image in a computer, monitoring the expansion change of the rock mass ice crack in real time, and positioning the cracking range.
S10: and (5) disassembling the device. And (3) detaching each measuring sensor and the cable, detaching the four-claw connecting mechanism and the loading device sleeve, opening the loading top plate and the loading side plate, and taking out the rock test piece.
S11: the test was repeated. Replacing the prepared saturated rock test piece, respectively setting different preset triaxial pressures and preset temperatures, repeating the test steps, and finally obtaining a plurality of groups of data for comparative analysis;
s12: and (5) sorting the data to obtain a conclusion. In each test, the data obtained by monitoring the acoustic emission and the frost heaving force in the test are recorded in real time, the fitting graph of each parameter of the acoustic emission and the frost heaving force, stress and strain is drawn, and the process from the temperature reduction of a rock body to the ice formation of water in a rock crack until the rock body is cracked is monitored. After all experiments are finished, the influence of different conditions on the expansion of the rock ice cracks is judged by analyzing the frost heaving fracture change of the rock body under different low-temperature environments, and the frost heaving expansion process of the rock ice cracks under different conditions is discussed.
The utility model discloses acoustic emission acquisition control system sets for the basic value of acoustic emission's load, energy isoparametric in advance, and data record good load, deformation, energy, count and amplitude isoparametric through obtaining in the testing process draws the stress strain figure under each parameter, can be vivid each stage and the process that corresponds the rock mass and break, and real-time supervision rock mass ice crack's frost heaving extension scope obtains the information of breaking.
The utility model discloses in when utilizing hand pump loading pressure, the predetermined value is set for to the stress of the three direction of rock test piece, three hand pump control around the rock test piece respectively, control, the stress of upper and lower three direction, during the pressurization, utilize three hand pump to load the minimum stress value sigma 3 in three direction stress, later utilize two remaining hand pumps with all the other two stress loading to middle stress value sigma 2, load the maximum stress value sigma 1 with last stress with a remaining hand pump at last, accomplish to this pressurization.
The utility model discloses frost heaving force measuring transducer is film pressure sensor, and the precision is higher, must mark the sensor before experimental, entangles film pressure sensor force measuring area with the film, pastes waterproof glue for the waterproof film in the crack surface, can repetitious usage.
The utility model discloses in set up different triaxial stress value and temperature for survey the rock mass and ice crack's under different compression environment and different low temperature environment extension evolution process, provide better foundation for cold district's rock mass prevention breaks.
The foregoing is a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the present invention, and these improvements and decorations should also be regarded as the protection scope of the present invention.
Claims (6)
1. The utility model provides a rock mass contains frozen swelling expansion process monitoring test system of ice crack network which characterized in that: including true triaxial loading device, temperature control collection system (16), frost heaving force collection control system (19) and acoustic emission collection system (20), true triaxial loading device is located inside freeze thawing environment box (1), it is fixed by self-lock device, temperature control collection system is located freeze thawing environment box (1) right side, whole temperature system relies on temperature sensor (15) in freeze thawing environment box (1) to monitor, frost heaving force collection control system (19) is through the frost heaving force measuring transducer of installing at rock test piece crack, convert the signal into the signal of telecommunication and carry for computer (17) terminal analysis, acoustic emission collection system (20) collect the cracked acoustic signal of rock mass through acoustic emission probe (9) and carry for computer (17).
2. The system for monitoring and testing the frost heave expansion process of the rock mass containing ice crack network according to claim 1, is characterized in that: the true triaxial loading device comprises a cable (2), a four-claw connecting mechanism (3), a loading device top plate (4), a loading device side plate (5), a pin (8), an acoustic emission probe (9), a loading device bottom plate (10), a hand pump (11) and a hand pump rod (12), wherein the loading device top plate (4), the loading device side plate (5) and the loading device bottom plate (10) form a closed loading space, the acoustic emission probe (9) is arranged in a loading base plate of the loading device side plate (5), the four-claw connecting mechanism (3) is arranged above the loading device top plate (4), the cable (2) is connected with a temperature control acquisition system (16), a freezing force acquisition control system (19) and a sound emission acquisition system (20), the loading device bottom plate (10) is connected with the four-claw connecting mechanism (3) through the pin (8), and three hand pumps (11) in the loading space are respectively connected with and control three directions of the loading device, the hand pump (11) is provided with a hand pump rod (12).
3. The system for monitoring and testing the frost heave expansion process of the rock mass containing ice crack network according to claim 1, is characterized in that: freezing and thawing environment box (1) side sets up visual heat preservation window (6), openly sets up environment box left door (7) and environment box right-hand member (14), and freezing and thawing environment box (1) side trompil is used for passing the cable, and trompil department sets up end cap (13), and freezing and thawing environment box (1) side internally mounted temperature sensor (15), temperature sensor connect temperature control collection system (16).
4. The system for monitoring and testing the frost heave expansion process of the rock mass containing ice crack network according to claim 1, is characterized in that: the temperature control acquisition system (16), the frost heaving force acquisition control system (19) and the acoustic emission acquisition system (20) are connected with a computer (17).
5. The rock mass ice-containing fracture network frost heave expansion process monitoring test system according to claim 2, characterized in that: a groove (21) is formed in the loading device side plate (5), and an acoustic emission probe (9) is arranged in the groove (21).
6. The rock mass ice-containing fracture network frost heave expansion process monitoring test system according to claim 2, characterized in that: and a water replenishing pipe (22) is embedded into the top plate (4) of the loading device.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111198136A (en) * | 2020-02-17 | 2020-05-26 | 北京科技大学 | Rock mass ice crack network frost heaving expansion process monitoring test system and method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111198136A (en) * | 2020-02-17 | 2020-05-26 | 北京科技大学 | Rock mass ice crack network frost heaving expansion process monitoring test system and method |
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