A method and system for calculating dynamic water infiltration of a soil-rock mixed accumulation landslide

Abstract

This invention relates to a method and system for calculating dynamic water infiltration in landslides of soil-rock mixed deposits, belonging to the field of disaster prevention and mitigation in civil engineering. It proposes a dynamic water infiltration rate considering both dynamic water intensity and the landslide slope angle. Based on this, equivalent permeability coefficients for the unsaturated and saturated infiltration stages of the deposit are constructed, considering the volume content of boulders. Subsequently, formulas for calculating the dynamic water infiltration depth in these two stages are derived, finally yielding a mathematical model of the infiltration depth throughout the entire dynamic water infiltration process of soil-rock mixed deposit landslides. This invention considers both unsaturated and saturated processes of dynamic water infiltration and takes into account the influence of three factors: dynamic water intensity, landslide slope angle, and boulder volume content. The calculation results are accurate, providing a theoretical basis for the stability analysis of soil-rock mixed deposit landslides and offering significant guidance for the prevention and control of such landslides.

Description

Technical Field

[0001] This invention relates to the field of slope seepage in civil engineering disaster prevention and mitigation, specifically a method and system for calculating dynamic water infiltration in landslides of soil-rock mixed deposits. Background Technology

[0002] Dynamic water infiltration generally refers to the process of dynamic water entering the soil vertically from the soil surface. The first stage of infiltration is the surface wetting stage, where the topsoil moisture content is low and the infiltration rate is high. With continuous rainfall or irrigation, the topsoil moisture content increases until the infiltration rate at the soil surface equals the rainfall intensity. Once the soil surface is saturated, the second stage begins, where the infiltration rate gradually decreases over time, and water begins to accumulate on the surface, even leading to runoff. After a relatively long period, the third stage begins, where the infiltration rate tends to stabilize. This stage is the profile-controlled stage, where the permeability is determined by soil properties.

[0003] Dynamic water (including reservoir water, rainfall, and snowmelt) is one of the main external factors inducing landslide disasters. The infiltration of dynamic water into the slope not only alters the seepage field of the landslide body itself but also changes the basic properties of the landslide soil, leading to landslide disasters under the combined influence of multiple factors. Therefore, studying methods for calculating dynamic water infiltration can better analyze the changing patterns of landslide soil parameters during the infiltration process. Currently, many models have been developed for studying dynamic water infiltration in soil-rock mixed deposit landslides, with the GA model being widely used. However, this model has significant shortcomings. On the one hand, it treats all infiltration surfaces as horizontal, failing to consider the influence of slope angle on dynamic water infiltration; on the other hand, it assumes the soil within the moist front is completely saturated, ignoring the existence of unsaturated infiltration, which is inconsistent with reality.

[0004] To address the aforementioned problems, this invention proposes a method for calculating the dynamic water infiltration in landslides involving mixed soil and rock deposits. This method divides the entire dynamic water infiltration process into an unsaturated infiltration stage and a saturated infiltration stage. It constructs a method for calculating the dynamic water infiltration depth in both stages, considering three factors: dynamic water intensity, landslide dip angle, and rock volume content. Finally, a mathematical model of the infiltration depth throughout the entire dynamic water infiltration process of landslides involving mixed soil and rock deposits is obtained. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention aims to provide a method and system for calculating dynamic water infiltration in landslides of mixed soil and rock deposits. Its fundamental feature lies in: constructing a dynamic water infiltration rate considering both dynamic water intensity and the landslide slope angle; constructing equivalent permeability coefficients for the unsaturated and saturated infiltration stages of the deposit considering the volumetric content of boulders; deriving calculation formulas for the dynamic water infiltration depth in these two stages; and finally obtaining a mathematical model of the infiltration depth throughout the entire dynamic water infiltration process of a mixed soil and rock deposit landslide. This invention has a clear approach and mature technology, completely overcoming the limitations of existing models that cannot consider the influence of slope angle on dynamic water infiltration and neglect the impact of the unsaturated infiltration stage. Furthermore, it incorporates the volumetric content of boulders in the landslide body, making it applicable to the analysis of infiltration patterns in mixed soil and rock deposit landslides under all dynamic water influences, and possessing promising application prospects.

[0006] The technical solution adopted by the present invention to solve the aforementioned technical problem is as follows: In a first aspect, the present invention provides a method for calculating dynamic water infiltration in landslides of mixed rock deposits, the method comprising the following: The entire process of dynamic water infiltration is divided into an unsaturated infiltration stage and a saturated infiltration stage. In the unsaturated infiltration stage, the dynamic water infiltration depth is calculated according to the following formula. : ; in, and These are the soil permeability coefficients at saturated water content and at initial water content, respectively. , This is an empirical coefficient, with a value ranging from 1.1 to 1.3; Indicates the volume content of the stone blocks; The slope angle of the landslide involving a mixture of soil and rock; For dynamic water intensity; During the saturated infiltration stage, the depth of dynamic water infiltration is... This can be obtained by solving the following equation:

[0007] parameter , , and The formula for calculation is:

[0008] In the above, For soil matrix suction; and These are the saturated volumetric moisture content and the initial volumetric moisture content, respectively. and t represents the saturation stage time; in the equation, the lower limit 0 on the left represents the infiltration depth of the entire unsaturated infiltration stage, and the lower limit 0 on the right represents the time of the entire unsaturated infiltration stage. The infiltration depth of dynamic water during the entire process of landslide in soil-rock mixture is the dynamic water infiltration depth during the saturated infiltration stage. The depth of dynamic water infiltration during the unsaturated infiltration stage sum.

[0009] Secondly, the present invention provides a dynamic water infiltration calculation system for landslides of mixed rock deposits, the system comprising: The module for calculating the dynamic water infiltration depth in the unsaturated infiltration stage is used to combine the soil saturated moisture content permeability coefficient and the initial moisture content permeability coefficient, the volume content of boulders, the landslide inclination angle of the soil-rock mixture, and the dynamic water intensity to obtain the dynamic water infiltration depth in the unsaturated infiltration stage, and at the same time determine the dynamic water infiltration time in the unsaturated infiltration stage. The dynamic water infiltration depth calculation module for the saturated infiltration stage is used to combine the permeability coefficient of soil saturated water content and the permeability coefficient under initial water content, the volume content of boulders, saturated volume water content, initial volume water content, soil matrix suction, and the dynamic water infiltration depth and time of the unsaturated infiltration stage determined by the dynamic water infiltration depth calculation module for the unsaturated infiltration stage, to obtain the dynamic water infiltration depth of the saturated infiltration stage. The infiltration depth calculation module for the entire process of dynamic water infiltration determines the infiltration depth of the entire process by combining the dynamic water infiltration depth in the unsaturated infiltration stage and the dynamic water infiltration depth in the saturated infiltration stage.

[0010] Furthermore, the system also includes a display module, which displays the calculation results and intermediate variables of each module, and can also display the infiltration process.

[0011] Compared with the prior art, the beneficial effects of the present invention are: 1. The method for calculating dynamic water infiltration in landslides of soil-rock mixed deposits in this invention has a wide range of applications. It is applicable to the analysis of infiltration patterns in landslides of soil-rock mixed deposits under the influence of all dynamic water. The method is simple, easy to understand and calculate.

[0012] 2. A novel dynamic water infiltration rate model was constructed that considers both dynamic water intensity and landslide inclination angle of the accumulation body. This model completely overcomes the limitations of existing models that cannot consider the influence of slope inclination angle on dynamic water infiltration, thus improving the accuracy of the calculation results.

[0013] 3. Innovative formulas for calculating the infiltration depth of dynamic water in the unsaturated and saturated infiltration stages were derived. The influence of dynamic water intensity, landslide dip angle and rock volume content were considered simultaneously. This solved the problem that existing models only considered the influence of a single infiltration stage. A more accurate mathematical model of the infiltration depth of dynamic water in the entire process of landslides in soil-rock mixtures was obtained, providing important scientific ideas for disaster prevention and mitigation in civil engineering. Attached Figure Description

[0014] Figure 1 This is a flowchart illustrating the method for calculating dynamic water infiltration in a landslide involving a soil-rock mixture, as described in this invention. Figure 2 The graph shows the dynamic water infiltration depth versus time obtained using Matlab software. Figure 3 Numerical model diagram of a landslide involving a soil-rock mixture; Figure 4 A comparison chart showing the relationship between dynamic water infiltration depth and time between the results of the moisture content monitoring meter (No. 1) and the numerical calculation results.

[0015] Figure 5 This is a comparison chart showing the relationship between dynamic water infiltration depth and time between the results of the moisture content monitoring meter (No. 2) and the numerical calculation results.

[0016] Figure 6 A comparison chart showing the relationship between dynamic water infiltration depth and time between the results of the moisture content monitoring meter (No. 3) and the numerical calculation results. Detailed Implementation

[0017] The present invention will be further described below with reference to the embodiments and accompanying drawings. The specific embodiments are only used to further illustrate the present invention and do not limit the scope of protection of this application.

[0018] For slopes / landslides, the infiltration plane is an inclined surface. This invention comprehensively considers the landslide dip angle, the unsaturated infiltration stage, and the saturated infiltration stage, while also incorporating the volume content factor of boulders in the soil into the calculation process. It proposes equivalent permeability coefficients for the unsaturated and saturated infiltration stages, constructs a unified infiltration rate formula that considers the landslide dip angle and dynamic water intensity, and then obtains the dynamic water infiltration depth of the two infiltration stages. Finally, the infiltration depth of the entire dynamic water infiltration process is obtained by summing them.

[0019] The present invention provides a method for calculating dynamic water infiltration in landslides involving mixed soil and rock deposits, which specifically includes the following steps: Step 1: Construct the dynamic water infiltration rate considering the dynamic water intensity and the landslide inclination angle of the accumulation body. The specific formula used is as follows: (a) Based on the slope angle of the soil-rock mixture landslide and dynamic water intensity If all the dynamic water infiltrates into the slope during the unsaturated infiltration stage, then the infiltration rate of the dynamic water on the vertical slope surface is expressed as: ; According to Darcy's law, the infiltration rate of dynamic water on a slope is... The depth of dynamic water infiltration in the direction perpendicular to the slope is , Let be the vertical infiltration depth of the dynamic water. Then, the simplified infiltration rate of the dynamic water on the slope is k (cos + / ); In the unsaturated infiltration stage, assuming that the infiltration rate of dynamic water on the vertical slope is equal to the infiltration rate of dynamic water on the sloping surface, the dynamic water infiltration rate on the landslide slope is obtained. for: (1) In the formula, For soil matrix suction, This represents the vertical depth of water infiltration. The equivalent permeability coefficient, In the unsaturated infiltration stage, the equation can be used directly. Obtain the infiltration depth of the unsaturated infiltration stage During the saturation infiltration stage, based on the formula This formula, combined with other formulas, yields the integral formula for infiltration depth. The equivalent permeability coefficient differs between the unsaturated and saturated infiltration stages.

[0020] Step 2: Construct the formula for calculating the dynamic water infiltration depth in the unsaturated infiltration stage. The specific formula used is as follows: (a) For a landslide containing a certain volume of boulders, the equivalent permeability coefficient in the unsaturated infiltration stage. The calculation formula is: (2) In the formula and These are the soil permeability coefficients at saturated water content and at initial water content, respectively. , This is an empirical coefficient, with a value ranging from 1.1 to 1.3; This indicates the volume content of boulders, which is the ratio of the volume of boulders to the total volume of the soil and rock mass. (b) Depth of dynamic water infiltration during the unsaturated infiltration stage With time The relationship is: (3) In the formula; and These are the saturated volumetric moisture content and the initial volumetric moisture content, respectively. (c) Substituting equations (3) and (2) into equation (1), we get Then Substituting into equation (3), we obtain the dynamic water infiltration depth in the unsaturated infiltration stage. : (4) Step 3: Construct the formula for calculating the dynamic water infiltration depth in the saturated infiltration stage. The specific formula used is as follows: (a) According to formula (1), the infiltration rate during the saturated infiltration stage. The calculation formula is: (5) In the formula; This is the equivalent permeability coefficient during the saturated infiltration stage; (b) Relationship between dynamic water infiltration depth and infiltration time during the saturated infiltration stage: (6) (c) Multiply and integrate Equations (5) and (6) to obtain the dynamic water infiltration depth in the saturated infiltration stage. Mathematical equation: (7) In the equation, the parameters , , and The calculation method is as follows: (8) and These are empirical values, with a range of -2 × 10⁻⁶. 3 ~-4×10 3 And 0.8~0.82; In the equation, the lower limit 0 on the left represents the infiltration depth of the entire unsaturated infiltration stage, and the lower limit 0 on the right represents the time of the entire unsaturated infiltration stage.

[0021] Step 4: The method for determining the infiltration depth of dynamic water infiltration throughout the entire process of a landslide involving a soil-rock mixture is as follows: (a) Solve equation (7) using Matlab or Python software, and combine equation (8) and equation (4) to obtain the infiltration depth of dynamic water infiltration during the entire process of landslide in soil-rock mixture. Calculation formula: (9).

[0022] Example 1 Assuming dynamic water intensity The slope angle is 40°. The soil saturation permeability coefficient is 30°. The initial soil permeability coefficient is 8. The empirical coefficient is 2.3. , and -3×10 3 0.8 and 1.2, volume content of boulders The saturated volumetric water content is 25%. The initial volumetric moisture content was 31%. It is 13%, soil matrix suction. It is 300.

[0023] according to Figure 1 The process described in this invention, which involves measuring the infiltration depth of dynamic water infiltration during the entire process of a landslide involving a soil-rock mixture, includes the following specific steps: Step 1, the infiltration rate of dynamic water on the landslide slope.

[0024] Step 2: Calculate the depth of dynamic water infiltration in the unsaturated infiltration stage according to formula (4). Approximately 35.40 mm, Step 3: According to formula (7), the depth of dynamic water infiltration in the saturated infiltration stage is obtained using Matlab software. The calculation formula is: (10) in, The calculation formula is: (11) Substituting the data, we can obtain The value is 0.083, which is then substituted into formula (10) to obtain the result; (12) Furthermore, according to formula (12), the relationship between the infiltration depth of dynamic water in the saturated infiltration stage and time t is expressed by a function. express;

[0025] Step 4, Formula for calculating the infiltration depth of dynamic water infiltration during the entire process of landslides involving mixed soil and rock deposits: (13) Finally obtained Figure 2 This is the curve showing the relationship between the depth of dynamic water infiltration and time, where t represents the time of the entire process of dynamic water infiltration in a landslide involving a soil-rock mixture.

[0026] Example 2 according to Figure 1 The process described in this invention uses a landslide involving a mixed soil and rock deposit in Hunan Province as a case study. ANSYS software was used to model and mesh the landslide, resulting in the numerical model shown below. Figure 3 As shown. The landslide elevation is 50 m, the longitudinal length is 60 m, the number of grids is 1275, and the physical and mechanical parameters of the landslide mass are set to a unit weight of 20.8 kN / m³. 3 The cohesion is 25.22 kPa, the internal friction angle is 12.23°, and the landslide dip angle is 28°. Assume dynamic water strength... The slope angle is 30. The soil saturation permeability coefficient is 30°. The initial soil permeability coefficient is 6. It is 2.5, empirical coefficient. , and -3×10 3 0.81 and 1.25, volume content of the stone The saturated volumetric moisture content is 30%. The initial volumetric moisture content was 34%. The soil matrix suction is 10%. The value is 600. Formula (9) was compiled using Python software and embedded into the software to calculate the relationship between dynamic water infiltration depth and time at different monitoring locations, as shown below. Figures 4-6 As shown.

[0027] Depend on Figures 4-6 It can be seen that the numerical calculation results of the dynamic water infiltration depth at different locations are basically consistent with the monitoring values ​​of the moisture content monitor, indicating that the results obtained by the dynamic water infiltration calculation model proposed in this patent are highly accurate; in addition, the dynamic water infiltration depth at different locations shows certain differences, which may be caused by the change in the content of boulders at different locations.

[0028] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A method for calculating dynamic water infiltration in landslides of mixed rock deposits, characterized in that, This method Includes the following: The entire process of dynamic water infiltration is divided into an unsaturated infiltration stage and a saturated infiltration stage. In the unsaturated infiltration stage, the dynamic water infiltration depth is calculated according to the following formula. : ； in, and These are the soil permeability coefficients at saturated water content and at initial water content, respectively. , This is an empirical coefficient, with a value ranging from 1.1 to 1.3; Indicates the volume content of the stone blocks; The slope angle of the landslide involving a mixture of soil and rock; For dynamic water intensity; During the saturated infiltration stage, the depth of dynamic water infiltration is... This can be obtained by solving the following equation: ， parameter , , and The formula for calculation is: ， In the above, For soil matrix suction; and These are the saturated volumetric moisture content and the initial volumetric moisture content, respectively. and t represents the saturation stage time; in the equation, the lower limit 0 on the left represents the infiltration depth of the entire unsaturated infiltration stage, and the lower limit 0 on the right represents the time of the entire unsaturated infiltration stage. The infiltration depth of dynamic water during the entire process of landslide in soil-rock mixture is the dynamic water infiltration depth during the saturated infiltration stage. The depth of dynamic water infiltration during the unsaturated infiltration stage sum.

2. The calculation method according to claim 1, characterized in that, The value ranges from 1.1 to 1.

3. and The value range is -2×10 3 ~-4×10 3 And 0.8~0.

82.

3. A system for calculating dynamic water infiltration in landslides of mixed rock deposits, characterized in that, The system includes: The module for calculating the dynamic water infiltration depth in the unsaturated infiltration stage is used to combine the soil saturated moisture content permeability coefficient and the initial moisture content permeability coefficient, the volume content of boulders, the landslide inclination angle of the soil-rock mixture, and the dynamic water intensity to obtain the dynamic water infiltration depth in the unsaturated infiltration stage, and at the same time determine the dynamic water infiltration time in the unsaturated infiltration stage. The dynamic water infiltration depth calculation module for the saturated infiltration stage is used to combine the permeability coefficient of soil saturated water content and the permeability coefficient under initial water content, the volume content of boulders, saturated volume water content, initial volume water content, soil matrix suction, and the dynamic water infiltration depth and time of the unsaturated infiltration stage determined by the dynamic water infiltration depth calculation module for the unsaturated infiltration stage, to obtain the dynamic water infiltration depth of the saturated infiltration stage. The infiltration depth calculation module for the entire process of dynamic water infiltration determines the infiltration depth of the entire process by combining the dynamic water infiltration depth in the unsaturated infiltration stage and the dynamic water infiltration depth in the saturated infiltration stage.

4. The system according to claim 3, characterized in that, The system also includes a display module, which displays the calculation results and intermediate variables of each module, and can display the infiltration process.

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