CN112730082A - Physical simulation test device for slope unloading excavation and use method thereof - Google Patents
Physical simulation test device for slope unloading excavation and use method thereof Download PDFInfo
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Abstract
The invention discloses a physical simulation test device for slope unloading excavation and a using method thereof, wherein the physical simulation test device comprises a prefabricated model frame, a loading system, a counterforce device, an experimental data monitoring module, an acquisition system and a simulation grading excavation system, wherein the output ends of the loading system and the counterforce device are in contact with the prefabricated model frame, the input ends of the experimental data monitoring module and the acquisition system are preset at monitoring positions of the prefabricated model frame, and the loading system and the counterforce device are controlled by the simulation grading excavation system; by monitoring the stress change of each part in the model and the strain of the generalized structural surface and the strain of the potential failure surface in the model in the simulation grading excavation process, the stability of the side slope after excavation can be analyzed in more detail.
Description
Technical Field
The invention relates to the technical field of slope unloading excavation, in particular to a physical simulation test device for slope unloading excavation and a using method thereof, which are experimental sample preparation molds for simulating a high-pressure slope excavation process, detecting information and further analyzing.
Background
Under the influence of the continuous rising of the Qinghai-Tibet plateau, the stability of the natural and artificial excavation high side slopes is extremely outstanding in the southwest and northwest areas of China, particularly in the east side area of the Huaqinghai-Tibet plateau, due to deep cutting of rivers and complex topographic and geological conditions, and constitutes one of the most distinctive engineering geology and rock mechanics problems in China;
when the stability of the slope is evaluated, theoretical calculation analysis methods are carried out, which mainly comprise a transfer coefficient method, a limit balance analysis method and the like, but any calculation method must be established on the basis of deeply ascertaining principle characteristics and making evolution mechanism analysis according with actual conditions. The information necessary for theoretical calculation is required to be obtained from a mechanical model, a mathematical model, a dominant factor and a sensitive factor.
Disclosure of Invention
In order to solve the problems, the invention discloses a physical simulation test device for slope unloading excavation and a using method thereof, which can analyze the stability of the slope after excavation in more detail by monitoring the stress change of each part in a model and the strain of a generalized structural surface and the strain of a potential failure surface in the model in the simulation grading excavation process.
In order to achieve the above purpose, the invention provides the following technical scheme:
the utility model provides a physical simulation test device of slope off-load excavation, includes prefabricated model frame, loading system, counterforce device, experimental data monitoring module and collection system, the hierarchical excavation system of simulation, the loading system with counterforce device's output termination with prefabricated model frame contact, experimental data monitoring module all predetermines with collection system's input the monitoring position of prefabricated model frame, loading system with counterforce device all receives the hierarchical excavation system control of simulation.
As a further description of the above technical solution:
the prefabricated model frame is made of a steel plate with the thickness of 2mm, the width of the mould is 20cm, the front face of the prefabricated model frame is consistent with the excavation face, and the side face of the prefabricated model frame is not sealed.
As a further description of the above technical solution:
the loading system is composed of a hydraulic pump, a pressure gauge, a one-way valve, a pressure reducing valve and hydraulic servo control, and loading and unloading are controlled in a manual control mode.
As a further description of the above technical solution:
the reaction device comprises a reaction frame, a hydraulic servo controller, a connecting steel frame and a base plate, wherein the output end of the hydraulic servo controller is connected with the prefabricated model frame through a cushion block, the hydraulic servo controller is installed on the reaction frame, and the hydraulic servo controller is connected with the reaction frame through the connecting steel frame.
As a further description of the above technical solution:
the test data monitoring module and the test data acquisition system mainly comprise a deformation damage monitoring module, a stress monitoring module, a strain monitoring module, other monitoring modules and a data acquisition system, wherein the deformation damage monitoring module comprises horizontal displacement, vertical displacement and crack monitoring, and the stress monitoring module comprises soil pressure monitoring and data acquisition.
As a further description of the above technical solution:
s1: generalizing a geological prototype, and selecting strong unloading rock masses, weak unloading rock masses and micro new rock masses according to corresponding lithology;
s2: simulating an excavation unloading scheme, simplifying actual excavation, and excavating according to the actual excavation scheme sequence;
s3: determining the similar normal maturity and the material ratio, and determining the material ratio by adopting a direct shear test;
s4: carrying out a test and collecting data, and arranging monitoring points;
s5: analysis was performed according to the experimental structure and the protocol was summarized.
As a further description of the above technical solution:
the test steps in S4 are:
(6) preparing similar materials, and filling the prefabricated model frame to form a model slope;
(7) installing and burying a soil pressure monitoring instrument while filling;
(8) after the simulated slope consolidation reaches a certain strength, demolding the model, transferring the model into a loading frame, installing a strain monitoring instrument, and setting displacement monitoring;
(9) installing a simulation grading excavation system, and performing simulation grading excavation by using the system;
monitoring and collecting various data are carried out at the same time of and after the simulation excavation.
As a further description of the above technical solution:
between the S4 and the S5: during and after the excavation is simulated, various data are monitored and collected, after initial loading is carried out to simulate the internal stress of an original slope body before excavation, the soil pressure and the strain in the model need to be collected for the first time, and the soil pressure and the strain are used as the original position and the stress condition of the model and used for subsequent analysis.
In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:
1. by monitoring the stress change of each part in the model and the strain of the generalized structural surface and the strain of the potential failure surface in the model in the simulation grading excavation process, the stability of the side slope after excavation can be analyzed in more detail.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a schematic diagram of a graded excavation structure;
FIG. 2 is a schematic diagram of a physical simulation test apparatus for slope unloading excavation;
FIG. 3 is a diagram showing the generalized results;
FIG. 4 is a table of physical and mechanical parameters of similar materials;
FIG. 5 is a table of physical and mechanical parameters of similar materials;
FIG. 6 shows the final ratio results;
FIG. 7 is a schematic view of the installation and burying positions of stress monitoring points;
FIG. 8 is a schematic view of a specific installation position of a strain monitor;
FIG. 9 is a schematic flow chart of the whole process of the experiment;
fig. 10 is a time flow chart of the unloading stage.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.
Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
It is noted that relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
This embodiment is a structure of physical simulation test device of side slope off-load excavation, including prefabricated model frame, loading system, counterforce device, experimental data monitoring module and collection system, the hierarchical excavation system of simulation, loading system with counterforce device's output termination with prefabricated model frame contact, experimental data monitoring module all predetermines with collection system's input the monitoring position of prefabricated model frame, loading system with counterforce device all receives the hierarchical excavation system control of simulation, prefabricated model frame is made by the steel sheet of thickness 2mm, and the mould width is 20cm, and the front is unanimous with the excavation face, and the side does not close the board, loading system comprises hydraulic pump, manometer, check valve, relief pressure valve and hydraulic servo control, controls adding the uninstallation through manual control's mode, counterforce device includes reaction frame, counter force device, The test system comprises a hydraulic servo control, a connecting steel frame and a base plate, wherein the output end of the hydraulic servo control is connected with the prefabricated model frame through a cushion block, the hydraulic servo control is installed on the reaction frame and is connected with the reaction frame through the connecting steel frame, the test data monitoring module and the acquisition system mainly comprise a deformation damage monitoring module, a stress monitoring module, a strain monitoring module, other monitoring modules and a data acquisition system, the deformation damage monitoring module comprises horizontal displacement, vertical displacement and crack monitoring, and the stress monitoring module comprises soil pressure monitoring and data acquisition;
it is worth noting that: the loading system, the counter-force device, the experimental data monitoring module, the acquisition system, the simulation grading excavation system and the like in the scheme are all common circuits or objects in the prior art, the innovation of the scheme is not on a single circuit, but a plurality of modules and circuits are matched for use, so that the purposes of monitoring the stress change of each part in the model and the strain of a generalized structural surface and the strain of a potential failure surface in the model in the simulation grading excavation process and analyzing the stability of the excavated side slope in more detail can be achieved;
in order to solve the problem of influence of continuous rising of Qinghai-Tibet plateau, the stability of natural and artificial excavation of high slope is prominent in the southwest and northwest areas of China, especially in the east area of the Huaqinghai-Tibet plateau, rivers are deeply cut, the topographic and geological conditions are complex, and the problem of stability of natural and artificial excavation of high slope is one of the most distinctive engineering geology and rock mechanics problems in China. The problem that information necessary for theoretical calculation is required to be obtained from a mechanical model, a mathematical model, a leading factor and a sensitive factor;
the invention is further elucidated below:
s1: generalizing a geological prototype, and selecting strong unloading rock masses, weak unloading rock masses and micro new rock masses according to corresponding lithology;
s2: simulating an excavation unloading scheme, simplifying actual excavation, and excavating according to the actual excavation scheme sequence;
s3: determining the similar normal maturity and the material ratio, and determining the material ratio by adopting a direct shear test;
s4: carrying out tests and data acquisition, arranging monitoring points, carrying out monitoring acquisition of various data at the same time of simulating excavation and after initial loading to simulate the internal stress of an original slope body before excavation, carrying out initial acquisition on the soil pressure and strain in the model, and taking the soil pressure and strain as the original position and stress condition of the model for later analysis;
(1) preparing similar materials, and filling the prefabricated model frame to form a model slope;
(2) installing and burying a soil pressure monitoring instrument while filling;
(3) after the simulated slope consolidation reaches a certain strength, demolding the model, transferring the model into a loading frame, installing a strain monitoring instrument, and setting displacement monitoring;
(4) installing a simulation grading excavation system, and performing simulation grading excavation by using the system;
(5) monitoring and collecting various data at the same time of simulating excavation and after;
s5: analyzing according to the experimental structure and summarizing the scheme;
the following further description is made by taking specific experiments as examples:
s1: the lithology of the exposed stratum of the left dam abutment of a certain hydropower station is mainly yingan rock and granite, the unloading action of the rock mass is stronger on the whole, and the slope rock mass has strong unloading rock mass, weak unloading rock mass and micro-new rock mass. In order to simulate the loading of the ground stress conveniently, the loading and unloading system is adopted to simulate the ground stress and the excavation in the test without considering the slope excavation body. In combination with the research purpose of the test, the operability of the test is considered, the side slope of the left dam abutment is properly simplified, and the final generalized result is shown in figure 3. Simplifying the structure surface in the side slope of the left dam abutment, selecting part of controlled structure surfaces fp13-1, YM8 and L72 according to site surface survey and adit survey, simulating the structure surfaces by river sand with the width of about 2mm, and simulating the excavation and the excavation before the excavation for simulating the excavation unloading by using the loading and unloading of a loading system in a test;
s2: and simplifying the actual excavation, excavating four times according to the sequence of the actual excavation scheme, and simulating the ground stress and excavation by using a loading and unloading system in the test.
According to the data of the earth stress field of the dam site area provided by the Guiyang institute, the actually measured maximum principal earth stress of the dam site area is in the NE-NEE direction as a whole, is basically consistent with the macroscopic judgment of the regional structure earth stress field, and locally exists in the NWW direction near the dam axis. According to the analysis of a pore diameter deformation stress relief method, the inclination direction is S inclination, the inclination angle is changed between 13 degrees and 78 degrees, and the inclination angle is more than 50 degrees and more than 60 degrees. The total ground stress of the dam site area tends to increase along with the buried depth, and meanwhile, the dam site area has an abnormal phenomenon because of the influence of the integrity degree, the structure and the landform of a rock body, and is shown as a section with crack development and poor rock body integrity, and the section is slightly low due to stress release. In the shallow portion of rock mass, because the not equidimension off-load of rock mass, ground stress has the release of not equidimension, and rock mass integrality is relatively poor, and the biggest main stress value is mostly about 10MPa, and is lower relatively. The ground stress value within the range of 50-220 m is 10-20 MPa (increasing along with the buried depth), and belongs to medium ground stress; the ground stress value is estimated to be more than 20MPa at the deep part (the part such as an underground factory building, the buried depth is 500-600 m), and the ground stress belongs to a high ground stress area. The maximum main ground stress direction sum value is simplified, the ground stress direction adopted in the test is NE direction, the inclination direction is S inclination, and the inclination angle is 50 degrees. The ground stress value within the range of 0-50 m is 0-10 MPa (increasing along with the buried depth), and the ground stress value within the range of 50-220 m is 10-20 MPa (increasing along with the buried depth).
And taking the ground stress at the middle position of each simplified excavation line as the ground stress loading value of the excavation line, and knowing that the ground stress values at the positions of the first-level excavation line, the second-level excavation line and the third-level excavation line are 2, 4.4 and 6Mpa according to the depth of the point. Considering the direction of the ground stress, and the axial direction of the dam is N17.27 degrees E, the component forces of the ground stress at each stage of excavation line in the axial direction of the dam are respectively 1.14 MPa, 2.5 MPa and 3.42MPa, and the direction is horizontally towards the inner side of the slope along the axial direction of the dam. Stress similarity constant C of the testσThen 1000, so in the physical simulation test the stress values near each excavation line are 1.14, 2.5, 3.42Kpa, directed horizontally into the slope along the dam axis; the stress values in the direction perpendicular to the excavation line along the dam axis and in the direction inwards of the slope are 0.86, 1.47, 2.54Kpa in the vicinity of each excavation line. The pressure of the hydraulic servo control piston and the stress at the excavation line are as follows:
Phydraulic servo control×SPiston area＝σStress at the excavation line×SArea of the pad
In the above formula, PHydraulic servo controlFor the hydraulic servo-control of the pressure in the cylinders, SPiston areaFor hydraulically servo-controlling the area of the piston, σStress at the excavation lineFor hydraulic servo control by means of a backing platePressure, S, applied at each excavation lineArea of the padIs the area of the pad. Wherein the piston area is 15.9cm2，SStress at the excavation line1.14 Kpa, 2.5 Kpa, 3.42Kpa, S respectivelyArea of the pad188, 350 and 574cm respectively2. Thus, PHydraulic servo controlRespectively 13.5, 55.1 and 123.5 Kpa.
In the initial state, the left dam abutment slope is pressurized to 13.5 Kpa, 55.1 Kpa and 123.5Kpa respectively through a three-stage loading system so as to simulate the situation before the left dam abutment slope is excavated. Then, the pressure of the first-stage loading system is reduced to 0 at the speed of 10Kpa/min, and the first-stage excavation is simulated. And after the pressure relief of the grade is finished, observing the development condition of the structural surface and the cracks of the side slope, and starting the next excavation after the deformation of the side slope is stable. Similarly, the same method is used for simulating excavation for the second-stage excavation and the third-stage excavation;
s3: for physical simulation tests of rock materials, determination of similar constants and selection and proportion of similar materials have great influence on physical and mechanical properties of the materials, and are also the key of success or failure of the simulation tests.
The similarity constant of the test is mainly determined according to three similarity theories, firstly, the geometric similarity ratio C is compared with the geometric similarity ratio C according to the actual size of the left dam abutment and the test conditionLWith a set value of 1000, the model size is: the horizontal length is 65.8cm, the vertical height is 50cm, the thickness is 20cm, and then the severe similarity constant C of each rock mass is testedγTo be 1, according to a similar theory: cσ＝Cγ·CLThe stress similarity constant C of the test can be obtainedσThen it is 1000. The stress similarity of the test mainly considers the similar shear strength of rock masses, the material proportion is determined by mainly adopting a direct shear test in the material proportion test, and the specific model test meets the requirements on the physical and mechanical parameters of similar materials, as shown in fig. 4 and 5;
s4: the model test steps mainly comprise:
(1) determining a similar constant and a similar material matching coefficient, determining the similar constant to be 1000 according to the geological prototype generalized condition and the actual physical mechanical parameters as described above, and then searching the optimal matching by adopting the test result in the 'similar constant and material matching', and finally obtaining a matching result as shown in FIG. 6;
(2) preparing similar materials, filling the prefabricated model frame to form a model side slope, manually stirring to prepare the similar materials for determining the proportion, filling the model according to the rock mass division and the model generalization condition of a typical section, wherein the model actual side slope mainly comprises three rock masses: strong unloading rock mass, weak unloading rock mass and micro-new rock mass, filling similar materials for test in a prefabricated model frame, and smearing lubricating oil on the low side and the edge of a prefabricated model box for smooth treatment in order to facilitate demoulding;
(3) the soil pressure monitoring instrument is installed and buried while filling, and as mentioned above, the test mainly needs to monitor and collect a series of indexes and data such as soil pressure, strain and the like, wherein the soil pressure box is installed and buried in the model when the model is laid. The specific installation and burying positions are shown in fig. 7. 5 rock mass stress monitoring points are arranged at the positions below the long and large cracks, the adit faults and the dikes and are arranged at the middle position of the model;
(4) after the simulated slope consolidation reaches a certain strength, demolding the model, transferring the model into a loading frame, installing a strain monitoring instrument, setting displacement monitoring, demolding the model after the slope model consolidation reaches a certain strength, transferring the model into the loading frame, installing the strain monitoring instrument, setting displacement monitoring, as mentioned above, after filling each layer of model and installing various monitoring devices, still needing a period of time, and transferring the model into the loading frame after the strength of the simulated slope reaches the strength which meets the stress similarity ratio and is preset by a proportioning material. At this time, the strain monitoring instrument is installed, the specific installation position is shown in figure 8, and 4 strain monitoring points are arranged on the long and large fissure, the adit fault and the dike. 2 strain gauges are arranged at each monitoring point and are arranged in a vertical crossing manner;
(5) the method comprises the steps of installing a simulation grading excavation system, using the simulation grading excavation system to simulate grading excavation, using the simulation grading excavation system to simulate ground stress by respectively loading 13.5 Kpa, 55.1 Kpa and 123.5Kpa on a base plate on an excavation surface by using hydraulic servo control after a simulation device is installed, attaching a strain gauge at a position designed on the surface of a model when the stress and the strain of the model tend to reach stress balance, slowly unloading by using the hydraulic servo control so as to simulate an excavation process, excavating three times according to an actual excavation scheme sequence, using the loading and unloading system to simulate grading excavation, monitoring and collecting various data during and after the simulation excavation, carrying out monitoring and collecting of the soil pressure and the strain in the model after initial loading to simulate the internal stress of an original slope before excavation, carrying out primary collection to serve as the original position and the stress condition of the model, for later analysis. Data including soil pressure, strain, displacement, structural planes, crack development distribution and the like are recorded and collected while the simulated excavation is carried out. The soil pressure and strain are continuously monitored and collected in the whole test process; and regularly photographing during the simulated excavation of the development distribution conditions of the displacement, the structural plane and the cracks, recording every 5 minutes of the simulated excavation, and additionally photographing for the development of local cracks.
S5: after simplifying the original side slope, the model has a 3-level excavation body, firstly simulating excavation to the elevation 2902m, then simulating excavation to the elevation 2810m, and finally simulating excavation to the elevation 2587m, wherein after the simulated excavation is finished each time, the development distribution of the caused soil pressure, strain, displacement, structural plane and fracture is not changed when continuous data acquisition and recording are carried out, and then the next step of side slope simulated excavation is carried out;
(1) various data were monitored and collected at the same time as and after the simulated excavation, and this test took a total of 7 hours and 40 minutes from 9:00:23 to 16:40:00, using "time point" as the time difference from 9:00:23 in min. The whole process flow of the test is shown in FIG. 9. Wherein, 0min-220min is used for preheating the static data acquisition instrument and checking the test instrument; 220-240 min is a simulated ground stress loading stage, and the loading stage is observation time except loading time; pasting a strain gauge on the model structure surface within 240-380 min, and waiting for the stabilization of data of the data instrument and the stabilization of viscose solidification; 380min-460min is an unloading stage, and the end of the unloading stage is the end of the test;
(2) the loading stage is not loaded in stages, the unloading stage needs to be loaded in three stages according to the requirements of a simulation test, the loading force is respectively 13.5 Kpa, 55.1 Kpa and 123.5Kpa, the loading mode adopts a manual drive loading system to unload at a constant speed, the unloading rate is 10Kpa, and the time flow chart is shown in FIG. 10;
(3) the main task of the whole test stage is to collect stress-time change data and strain-time change data, and record the macroscopic phenomenon of the model in the test by using a camera, and the main purpose is to analyze the stress-time change rule and the strain-time change rule by using office software, analyze the failure phenomenon by arranging photos, and analyze the failure mechanism of unloading excavation response by combining the stress-strain rule and the existing failure phenomenon;
s6: and in the test process, the strain is measured only in unloading, and in the simulated excavation process, fp13-1 is influenced by the simulated three-stage excavation, is influenced most by the simulated first excavation and is finally opened by about 1 mm. At one-level excavation face rear portion locking section position, in the three-level excavation process of simulation, constantly taking place to warp, along with the development of time, probably take place bigger displacement. YM8 is continuously opened while the displacement of L72 is continuously fluctuated in the process of simulating three-stage excavation.
In conclusion, by monitoring the stress change of each part in the model and the strain of the generalized structural surface and the strain of the potential failure surface in the model in the simulation grading excavation process, the stability of the excavated side slope can be analyzed in more detail.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.
Claims (8)
1. The utility model provides a physical simulation test device of side slope off-load excavation which characterized in that: including prefabricated model frame, loading system, counterforce device, experimental data monitoring module and collection system, the hierarchical excavation system of simulation, the loading system with counterforce device's output termination with prefabricated model frame contact, experimental data monitoring module all presets with collection system's input the monitoring position of prefabricated model frame, loading system with counterforce device all receives the hierarchical excavation system control of simulation.
2. The physical simulation test device for slope unloading excavation according to claim 1, characterized in that: the prefabricated model frame is made of a steel plate with the thickness of 2mm, the width of the mould is 20cm, the front face of the prefabricated model frame is consistent with the excavation face, and the side face of the prefabricated model frame is not sealed.
3. The physical simulation test device for slope unloading excavation according to claim 2, characterized in that: the loading system is composed of a hydraulic pump, a pressure gauge, a one-way valve, a pressure reducing valve and hydraulic servo control, and loading and unloading are controlled in a manual control mode.
4. The physical simulation test device for slope unloading excavation according to claim 3, characterized in that: the reaction device comprises a reaction frame, a hydraulic servo controller, a connecting steel frame and a base plate, wherein the output end of the hydraulic servo controller is connected with the prefabricated model frame through a cushion block, the hydraulic servo controller is installed on the reaction frame, and the hydraulic servo controller is connected with the reaction frame through the connecting steel frame.
5. The physical simulation test device for slope unloading excavation according to claim 4, characterized in that: the test data monitoring module and the test data acquisition system mainly comprise a deformation damage monitoring module, a stress monitoring module, a strain monitoring module, other monitoring modules and a data acquisition system, wherein the deformation damage monitoring module comprises horizontal displacement, vertical displacement and crack monitoring, and the stress monitoring module comprises soil pressure monitoring and data acquisition.
6. A method of using a physical simulation test device for slope unloading excavation is characterized in that:
s1: generalizing a geological prototype, and selecting strong unloading rock masses, weak unloading rock masses and micro new rock masses according to corresponding lithology;
s2: simulating an excavation unloading scheme, simplifying actual excavation, and excavating according to the actual excavation scheme sequence;
s3: determining the similar normal maturity and the material ratio, and determining the material ratio by adopting a direct shear test;
s4: carrying out a test and collecting data, and arranging monitoring points;
s5: analysis was performed according to the experimental structure and the protocol was summarized.
7. The physical simulation test device for slope unloading excavation according to claim 6, characterized in that:
the test steps in S4 are:
(1) preparing similar materials, and filling the prefabricated model frame to form a model slope;
(2) installing and burying a soil pressure monitoring instrument while filling;
(3) after the simulated slope consolidation reaches a certain strength, demolding the model, transferring the model into a loading frame, installing a strain monitoring instrument, and setting displacement monitoring;
(4) installing a simulation grading excavation system, and performing simulation grading excavation by using the system;
(5) monitoring and collecting various data are carried out at the same time of and after the simulation excavation.
8. The physical simulation test device for slope unloading excavation according to claim 7, characterized in that:
between the S4 and the S5: during and after the excavation is simulated, various data are monitored and collected, after initial loading is carried out to simulate the internal stress of an original slope body before excavation, the soil pressure and the strain in the model need to be collected for the first time, and the soil pressure and the strain are used as the original position and the stress condition of the model and used for subsequent analysis.
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