Method for testing and characterizing the performance of earth-rockfill dam termite nest wall materials and the disaster-causing mechanism

Abstract

The application discloses a kind of earth-rock dam termite nest wall material performance test and disaster-causing mechanism characterization method, it is related to water conservancy engineering geotechnical test and termite disaster prevention and control technical field, comprising the following steps: from the white ant nest hole of the earth-rock dam to be measured in occurrence collected complete nest wall undisturbed soil sample as test sample, determine its natural moisture content, liquid plastic limit, particle size distribution and density etc.Basic physical parameters;Carry out disintegration, scouring test respectively simulate static water immersion and dynamic water scouring condition, obtain water physical parameter;Three kinds of microtest are carried out to obtain structural characteristics;Compare results to identify different water response, determine the stage false strength disaster-causing characteristic;The application establishes the full-dimensional test system of basic physical parameter, water physical property and microstructure, reveals the different response mechanism and stage false strength disaster-causing law of static water continuous disintegration, dynamic water erosion resistance in nest wall material, provides scientific theoretical basis and technical support for earth-rock dam termite hazard prevention and control.

Description

Technical Field

[0001] This invention relates to the field of geotechnical testing for water conservancy projects and termite disaster prevention and control, specifically to a method for testing the performance of termite nest wall materials in earth-rock dams and characterizing their disaster-causing mechanisms. Background Technology

[0002] Earth-rock dams are the most numerous and widely distributed type of dam in my country's water conservancy system, undertaking core functions such as flood control, irrigation, water supply, and power generation. Their safe operation is directly related to national economy, people's livelihood, and public safety. Termite infestation is one of the most significant biological hazards threatening the long-term safety and stability of earth-rock dams. The complex nesting systems built by termites inside the dam body can damage the integrity of the soil structure, weaken the dam's seepage resistance, and thus lead to leakage, piping, and even dam failure.

[0003] However, current research on termite nest wall materials for earth-rock dams, both domestically and internationally, still suffers from significant shortcomings: First, existing standards such as the "Standard for Geotechnical Testing Methods" lack a specific testing system for termite nest walls, a special type of biologically modified soil. Conventional geotechnical testing methods cannot accurately characterize its unique engineering properties, resulting in highly discrete and incomparable test results. Second, existing testing methods for hydrological properties, a key factor affecting the stability of nest wall structures, have significant deficiencies. Disintegration tests use general calculation formulas without considering the systematic errors of non-standard testing instruments, leading to distorted disintegration rate calculations. Scour tests lack specialized devices adapted to nest wall materials, failing to simulate the actual dynamic water scour conditions inside the dam. Finally, existing research has failed to systematically elucidate the differentiated response mechanisms of nest wall materials under static water immersion and dynamic water scour, and there is insufficient understanding of the staged false strength phenomenon during instability. This makes it impossible to accurately describe the dynamic evolution of nest cavity formation and soil erosion, resulting in a lack of solid theoretical support for termite damage control in earth-rock dams, with control technologies remaining at the empirical level for a long time. Summary of the Invention

[0004] The purpose of this invention is to provide a method for testing the performance of termite nest wall materials in earth-rock dams and characterizing their disaster-causing mechanisms, in order to solve the problems in the existing technology of lacking specific testing methods for termite nest walls, distorted hydrophysical property test results, and unclear differential response mechanisms and staged false intensity disaster-causing patterns.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for testing the performance of termite nest wall materials in earth-rock dams and characterizing their disaster-causing mechanisms, comprising the following steps:

[0006] S1. Collect undisturbed soil samples of the termite nests in the earth-rock dam to be tested, and use the undisturbed soil samples of the nest walls as nest wall material samples. Determine the natural moisture content, liquid limit, plastic limit, particle size distribution and density of the nest wall material samples.

[0007] S2. Disintegration test and erosion test are performed on the nest wall material sample to obtain the disintegration amount and impact coefficient; wherein the disintegration test uses the modified disintegration rate calculation formula to calculate the disintegration amount at different times;

[0008] S3. The nest wall material sample is subjected to scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and mercury porosimetry (MIP) to obtain its microstructure, chemical composition, and pore structure characteristics.

[0009] S4. By comparing the results of the disintegration test and the scouring test, the differential response characteristics of the nest wall material sample are identified: the structural integrity of the sample is slowly lost under static water conditions and the surface peeling is limited under dynamic water conditions. Based on this, the staged pseudo-strength characteristics of the nest wall material that still maintains its structural morphology after instability are determined.

[0010] Further, in step S2, the disintegration test uses a 5cm cube reshaped sample made from the nest wall material sample according to the measured physical parameters. The sample is completely immersed in room temperature water, and the float scale readings are recorded at 1, 3, 10, 30, and 60 minutes. The disintegration rate is calculated using the following formula:

[0011]

[0012] in, The percentage of sample disintegration at time t. This is the scale reading at time t when the buoy is flush with the waterline. This is the instantaneous stable reading of the scale at the point where the float is level with the water surface at the start of the test; This refers to the stable readings of the scale at the water level of the empty buoy and net before the start of the experiment.

[0013] Furthermore, in step S2, the scouring test uses a 60cm sample of the nest wall material. 3 For the ring sample, a simple flushing device consisting of a constant pressure water tank, a nozzle, and a sample holder was used. The nozzle was kept 15 cm away from the sample surface, and the sample surface was flushed with a constant flow of water at a rate of 16.62 L / h for 10 minutes.

[0014] Furthermore, the scouring test uses a drying method to determine the dry mass loss of the sample before and after scouring, and the impact resistance coefficient is calculated using the following formula:

[0015]

[0016] in, Impact resistance coefficient (L / g); The flushing flow rate (L / min); The flushing time is in minutes. The mass of dried mud and sand (g).

[0017] Furthermore, in step S3, scanning electron microscopy (SEM) is used to observe the particle arrangement, cement distribution, and fiber bridging structure of the nest wall material sample at magnifications of ×300x and ×1000x, respectively.

[0018] Fourier Transform Infrared (FTIR) Spectroscopy Analysis 400-4000 cm⁻¹ -1 Functional group characteristics within the wavenumber range are used to identify the chemical composition of organic cements;

[0019] Mercury intrusion porosimetry (MIP) was used to determine the porosity, pore size distribution, median pore size, and tortuosity parameters of the nest wall material sample.

[0020] Furthermore, in step S4, the differentiated response characteristics are as follows: the amount of disintegration continues to increase within 60 minutes of immersion in still water and does not completely disintegrate; within 10 minutes of rinsing with moving water, the mass loss rate is less than 10% and there is no structural damage.

[0021] Furthermore, in step S4, the staged pseudo-strength characteristic is as follows: the internal organic cement network of the nest wall material sample gradually hydrolyzes and disintegrates under static water conditions, while the smooth surface of the nest wall and the residual cement structure inhibit particle peeling under dynamic water conditions.

[0022] Compared with existing technologies, this invention provides a method for testing the performance and characterizing the disaster-causing mechanism of termite nest wall materials in earth-rock dams. By establishing a comprehensive standardized testing system for the basic physical parameters, hydrophysical properties, and microstructure of termite nest wall materials in earth-rock dam engineering scenarios, it fills the gap in existing standards for specific testing methods for this special biologically modified soil, improving the accuracy and comparability of test results. Furthermore, it corrects the disintegration rate calculation formula under non-standard instruments, solving the problem of calculation distortion caused by instrument differences in traditional formulas. It also realistically simulates the dynamic water scouring conditions inside the dam body using a simple scouring device, achieving precise quantification of the hydrophysical properties of the nest wall material. The invention reveals the differentiated response mechanism of the nest wall material—"continuous disintegration in static water and resistance to scouring in dynamic water"—clarifies the disaster-causing law of its staged false strength during instability, and elucidates the dynamic evolution process of nest cavity formation and soil erosion. This provides a solid theoretical basis for the early identification, risk assessment, and formulation of control measures for termite damage in earth-rock dams. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0024] Figure 1This is a diagram of a termite nest and sampled nest wall material in an embodiment of the present invention.

[0025] Figure 2 This is a diagram illustrating the geotechnical test process in an embodiment of the present invention; wherein, Figure 2 Figure a shows the process of the density test using the wax sealing method. Figure 2 b is a diagram of the particle analysis test process using the hydrometer method. Figure 2 c is a diagram of the test process for the limit moisture content;

[0026] Figure 3 This is the particle size distribution curve of the termite nest wall in an embodiment of the present invention;

[0027] Figure 4 This is a diagram illustrating the preparation of the disintegration test specimen in an embodiment of the present invention; wherein, Figure 4 a represents a cubic sample prepared using a mold. Figure 4 b means the sample is completely immersed in a transparent container filled with room temperature water;

[0028] Figure 5 A diagram illustrating the disintegration test process in an embodiment of the present invention;

[0029] Figure 6 A diagram illustrating the scouring test process in an embodiment of the present invention;

[0030] Figure 7 Image showing the completed scouring process of the termite nest wall material in this embodiment of the invention;

[0031] Figure 8 The SEM microstructure of the natural termite nest wall in this embodiment of the invention, wherein, Figure 8 a is a magnified image of 300x. Figure 8 b is a magnified image of 1000x;

[0032] Figure 9 This is the cumulative pore volume distribution curve of the natural termite nest wall material tested by mercury intrusion porosimetry in an embodiment of the present invention;

[0033] Figure 10 The image shows the Fourier transform infrared (FTIR) spectrum test results of the natural termite nest wall material in this embodiment of the invention. Detailed Implementation

[0034] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] Example 1

[0036] This embodiment takes a termite nest found within an earth-rock dam as the research object, and uses the method described in this invention to conduct comprehensive performance testing and disaster-causing mechanism analysis on its nest wall material. The specific steps are as follows:

[0037] Step 1, as follows Figure 1 As shown, intact soil samples of the termite nest wall were collected from a termite nest at a depth of 8-12m inside the earth-rock dam. The soil samples were yellowish-brown in color and contained no obvious impurities. The collected undisturbed soil samples were sealed and transported back to the laboratory as nest wall material samples. Their basic physical parameters were determined according to the "Standard for Geotechnical Testing Methods" (GB / T50123-2019), as shown in Table 1 below.

[0038] Table 1. Basic physical properties of soil samples from the nest wall

[0039]

[0040] Natural moisture content: determined by the drying method, the result was 17.9%;

[0041] Liquid limit: such as Figure 2 As shown in c, the liquid limit and plastic limit were determined using the combined liquid limit and plastic limit test method. The liquid limit was 30.5%, the plastic limit was 12.7%, and the plasticity index was 17.8, which indicates that the soil is of medium plasticity.

[0042] Particle size distribution: such as Figure 2 As shown in b, using a combination of sieving and hydrometer methods, the content of particles larger than 0.075 mm was 61.5%, and no particles larger than 2 mm were detected, classifying it as clayey sand; the coefficient of uniformity was 24, the coefficient of curvature was 1.2, and the gradation was good.

[0043] Density: such as Figure 2 As shown in figure a, the wet density, determined using the wax-sealing method, is 1.74 g / cm³. 3 The dry density is 1.48 g / cm³. 3 Based on the soil particle specific gravity of 2.66, the void ratio is calculated to be approximately 0.80.

[0044] Step 2, Disintegration Test:

[0045] Since the original soil of the nest wall was fragmented and could not meet the requirements of the specimen, a remolded soil sample was prepared according to the basic physical parameters determined in step 1; for example... Figure 4 As shown, a cubic sample with a side length of 5 cm was prepared using a mold. The sample was completely immersed in a transparent container filled with room temperature water, and timing was started immediately.

[0046] like Figure 5 As shown, the initial stable readings of the scale at the water surface of the empty float and screen of the disintegration apparatus used in this experiment are not the fixed value of 100 in the traditional formula. Therefore, the modified disintegration rate calculation formula is used for calculation, and the formula is expressed as:

[0047]

[0048] in, The percentage of sample disintegration at time t. This is the scale reading at time t when the buoy is flush with the waterline. This is the instantaneous stable reading of the scale at the point where the float is level with the water surface at the start of the test; This refers to the stable readings of the scale at the water level of the empty buoy and net before the start of the experiment.

[0049] Before the experiment began, stable readings of the scales at the water level of the empty float and the net were measured. =76; After immersing the sample in water, measure the instantaneous stable reading of the scale at the water surface of the float at the start of the test. =17. Record the scale readings at the float level with the water surface at 1, 3, 10, 30, and 60 minutes respectively. And calculate the amount of disintegration at the corresponding time. The results are shown in Table 2 below:

[0050] Table 2 Results of the disintegration test on the nest wall soil samples

[0051]

[0052] Table 2 shows that the nest wall material exhibited a clear trend of continuous disintegration under static water immersion conditions. At the beginning of the experiment (1 minute), the soil sample was in the water absorption stage, maintaining its basic morphology and initial wet strength. The float reading difference was -1, and the disintegration rate was -1.69%, indicating that the sample initially gained weight from water absorption. At 3 minutes, fine cracks began to appear on the sample surface, and air bubbles continuously escaped from the cracks, with a disintegration rate of 5.08%. As the immersion time increased, the cracks gradually expanded, and particles gradually peeled off from the sample edges and surface. At 10 minutes, the disintegration rate was 16.95%, at 30 minutes it reached 27.12%, and at 60 minutes it increased to 50.85%, with the disintegration process stabilizing. These results indicate that under the influence of water molecule penetration, the internal cementing network of the nest wall material gradually breaks down, the structural integrity is slowly lost, and it exhibits continuous disintegration characteristics.

[0053] scouring test:

[0054] Use a simple flushing device, such as Figure 6 As shown, the device mainly consists of a constant pressure water tank, a nozzle, and a sample holder. Remolded soil samples were prepared according to the physical parameters measured in step 1, and then passed through a 60cm... 3 After sampling with a ring cutter, the sample is fixed in the rinsing tank, keeping the distance between the nozzle and the sample surface at 15 cm. The sample surface is rinsed with a constant flow of water at a rate of 16.62 L / h for 10 min.

[0055] The dry weight loss of the soil sample before and after erosion was determined using the oven-drying method. The initial dry weight was 88.5 g, and the dry weight after erosion was 80.9 g, resulting in a dry weight loss of 7.6 g, or approximately 8.6%. The erosion resistance coefficient was calculated using the formula:

[0056]

[0057] in, Impact resistance coefficient (L / g); The flushing flow rate (L / min); The flushing time is in minutes. The mass of dried mud and sand (g).

[0058] like Figure 7 As shown, after scouring, the sample surface was observed to show only slight abrasion marks, with no obvious erosion pits or structural damage, and the overall shape of the sample remained intact. Analysis suggests that this phenomenon is related to the smooth inner wall formed by termites bonding and repeatedly applying saliva during nest building. Water encounters less resistance when flowing along the smooth surface, making it difficult for particles to be detached, thus exhibiting limited scouring loss.

[0059] Step 3, Scanning Electron Microscopy (SEM) Test:

[0060] The dried nest wall material samples were prepared for electron microscopy, and their microstructure was observed at magnifications of 300x and 1000x, respectively. Figure 8 It is evident that the overall structure of the nest wall material is relatively dense, but there are numerous irregular pores between the particles, with varying pore sizes and some interconnected pores. The particle surface is clearly coated with organic cementitious material, which is widely distributed and relatively continuous. This is the result of termites binding and piling up soil particles using secretions such as saliva during nest building. Further magnified observation reveals that fine and coarse particles are alternately distributed, with surface contact and cemented contact being the main modes of contact between particles. The cemented film thickness is uneven, and the organic cementitious material forms a thin film or flocculent coating around the particle surface and fills the gaps between particles, forming a relatively stable cemented skeleton. Locally, cemented bridging structures are visible connecting adjacent particles, enhancing the bonding strength between particles. In addition, a small number of fibrous bridging structures can be observed in the image, indicating that the nest wall material contains fibers left over from termites consuming plants, which also serve as a reinforcement mechanism.

[0061] Fourier Transform Infrared Spectroscopy (FTIR) Test:

[0062] FTIR testing was performed on the nest wall material samples. Figure 10 It can be seen that the analysis of 400-4000cm -1 Functional group characteristics within the wavenumber range. Test results show that at 3620 cm⁻¹... -1An obvious hydroxyl (-OH) stretching vibration peak appears at , which reflects the content of structural water and organic hydroxyl groups; 2929 cm -1 -1, a weak double C-H stretching vibration peak appears nearby, indicating that the material contains a small amount of organic matter; 1636 cm -1 -1, an amide C=O peak appears at , which reflects the presence of a small amount of protein-based organic matter; 1439 cm -1 -1, the CO3 2- 2- asymmetric stretching at this position and 874 cm -1 -1, the CO3 2- 2- bending vibration at this position together indicate that the material has undergone slight carbonization; 1026 cm -1 -1 and 777 cm -1 -1, strong absorption peaks appear, which are asymmetric stretching vibration peaks of Si-O-T (T=Si / Al), reflecting that the clay aggregate content is abundant.

[0063] Mercury intrusion porosimetry (MIP) test:

[0064] The mercury intrusion method was used to determine the pore structure characteristic parameters of the nest wall material. The results show that the porosity of the nest wall material is 36.11%, the median pore diameter is 2452.92 nm, the average pore diameter is 169.15 nm, and the tortuosity is 20.1764. The pore size distribution range is relatively wide, as can be seen from Figure 9 , the pore size distribution of the nest wall material presents a significant multi-peak characteristic with an extremely wide span, indicating that the pores in the nest wall material are composed of pore groups of different size levels. Among them, the main peak is located at 1889 nm, where the peak value of logarithmic differential mercury intrusion is the largest (close to 0.16), which belongs to the range of "macropores" (1000 nm < r). Meanwhile, several other obvious peaks are also marked in the figure, such as 25 nm (transition pore region), 7494 nm, 27429 nm, and 52530 nm. These peaks together constitute the pore size distribution characteristics of the material with an extremely wide span and complex structure; the existence of small peaks in the gel pore and transition pore regions indicates that the material also contains fine pores internally. Corresponding to the above content, the frequent fluctuations on the curve combined with the high tortuosity parameter of 20.1764 indicate that the pore connection channels inside the termite nest wall are not single and straight, the pore structure is complex and uneven, forming a multi-level complex pore network matching the cementation mechanism of saliva and particle accumulation during termite nesting.

[0065] Step 4: Comparing the results of the disintegration test and the scouring test, it can be seen that the termite nest wall material of the earth-rock dam shows significant differentiated hydraulic response characteristics: under static water immersion conditions, the material continues to disintegrate, the disintegration amount reaches 50.85% within 60 min and does not completely disintegrate, and the structural integrity is slowly lost; while under dynamic water scouring conditions, the mass loss rate is only 8.6% within 10 min, there is no structural damage, and the surface peeling is limited.

[0066] The formation mechanism was analyzed based on the microscopic test results: Under static water conditions, water molecules gradually penetrate into the interior of the material, destroying the hydrogen bond connections between the organic cement and clay particles, leading to the gradual hydrolysis of the organic cement network and a decrease in the interparticle bonding strength, thus triggering continuous disintegration; while under dynamic water conditions, the smooth inner wall formed by termite nests reduces the shear force of water flow on the wall surface, and the remaining cement structure can still maintain a certain degree of particle bonding, inhibiting the large-scale peeling of particles.

[0067] This differentiated response characteristic causes the termite nest wall material to exhibit a distinct staged pseudo-strength feature during instability: the internal cementing network of the material gradually breaks down, and the overall strength is significantly reduced, but it can still maintain a certain structural shape and will not immediately collapse. This feature allows termite nests to gradually expand and form cavities under the seepage action of the dam, while not blocking the seepage channels due to rapid collapse, thus preventing disasters such as leakage and piping.

[0068] in conclusion

[0069] This embodiment employs the testing and characterization methods described in this invention to comprehensively determine the basic physical parameters, hydrophysical properties, and microstructural characteristics of a termite nest wall material in an earth-rock dam. It accurately reveals the differentiated response mechanism of "continuous disintegration in static water and erosion resistance in dynamic water" and the phased pseudo-intensity disaster-causing pattern, verifying the scientific validity and effectiveness of the method of this invention. This method can provide standardized technical means for engineering testing and disaster analysis of various termite nest wall materials in earth-rock dams, and provide a reliable theoretical basis for the prevention and control of termite damage in earth-rock dams.

[0070] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for testing the performance of termite nest wall materials in earth-rock dams and characterizing their disaster-causing mechanisms, characterized in that, Includes the following steps: S1. Collect undisturbed soil samples of the termite nests in the earth-rock dam to be tested, and use the undisturbed soil samples of the nest walls as nest wall material samples. Determine the natural moisture content, liquid limit, plastic limit, particle size distribution and density of the nest wall material samples. S2. Disintegration test and erosion test are performed on the nest wall material sample to obtain the disintegration amount and impact coefficient; wherein the disintegration test uses the modified disintegration rate calculation formula to calculate the disintegration amount at different times; S3. The nest wall material sample is subjected to scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and mercury porosimetry (MIP) to obtain its microstructure, chemical composition, and pore structure characteristics. S4. By comparing the results of the disintegration test and the scouring test, the differential response characteristics of the nest wall material sample are identified: the structural integrity of the sample is slowly lost under static water conditions and the surface peeling is limited under dynamic water conditions. Based on this, the staged pseudo-strength characteristics of the nest wall material that still maintains its structural morphology after instability are determined.

2. The method for testing the performance of termite nest wall materials in earth-rock dams and characterizing their disaster-causing mechanisms according to claim 1, characterized in that, In step S2, the disintegration test uses a 5cm cube reshaped sample made from the nest wall material sample according to the measured physical parameters. The sample is completely immersed in room temperature water, and the float scale readings are recorded at 1, 3, 10, 30, and 60 minutes. The disintegration rate is calculated using the following formula: in, The percentage of sample disintegration at time t. This is the scale reading at time t when the buoy is flush with the waterline. This is the instantaneous stable reading of the scale at the point where the float is level with the water surface at the start of the test; This refers to the stable readings of the scale at the water level of the empty buoy and net before the start of the experiment.

3. The method for testing the performance of termite nest wall materials in earth-rock dams and characterizing their disaster-causing mechanisms according to claim 1, characterized in that, In step S2, the scouring test uses a 60cm sample of the nest wall material. 3 For the ring sample, a simple flushing device consisting of a constant pressure water tank, a nozzle, and a sample holder was used. The nozzle was kept 15 cm away from the sample surface, and the sample surface was flushed with a constant flow of water at a rate of 16.62 L / h for 10 minutes.

4. The method for testing the performance of termite nest wall materials in earth-rock dams and characterizing their disaster-causing mechanisms according to claim 3, characterized in that, The scouring test uses the drying method to determine the dry mass loss of the sample before and after scouring, and the impact resistance coefficient is calculated using the following formula: in, Impact resistance coefficient (L / g); The flushing flow rate is (L / min). The flushing time is in minutes. The mass of dried mud and sand (g).

5. The method for testing the performance of termite nest wall materials in earth-rock dams and characterizing their disaster-causing mechanisms according to claim 1, characterized in that, In step S3, scanning electron microscopy (SEM) is used to observe the particle arrangement, cement distribution, and fiber bridging structure of the nest wall material sample at magnifications of ×300x and ×1000x, respectively. Fourier Transform Infrared (FTIR) Spectroscopy Analysis 400-4000 cm⁻¹ -1 Functional group characteristics within the wavenumber range are used to identify the chemical composition of organic cements; The porosity, pore size distribution, median pore size, and tortuosity parameters of the nest wall material sample were determined by mercury porosimetry (MIP).

6. The method for testing the performance of termite nest wall materials in earth-rock dams and characterizing their disaster-causing mechanisms according to claim 1, characterized in that, In step S4, the differentiated response characteristics are as follows: the amount of disintegration continues to increase within 60 minutes of immersion in still water and does not completely disintegrate; within 10 minutes of rinsing with moving water, the mass loss rate is less than 10% and there is no structural damage.

7. The method for testing the performance of termite nest wall materials in earth-rock dams and characterizing their disaster-causing mechanisms according to claim 1, characterized in that, In step S4, the staged false strength characteristic is as follows: the internal organic cement network of the nest wall material sample gradually hydrolyzes and disintegrates under static water conditions, while the smooth surface of the nest wall and the residual cement structure inhibit particle peeling under dynamic water conditions.

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