A method for transforming ecological terraces in arid sandy land

Abstract

This invention relates to the fields of ecological environment management and agricultural water and soil engineering, specifically a method for transforming ecological terraces in arid sandy land. The method includes: acquiring particle size distribution and shear characteristics data of the substrate sand, determining the sidewall inclination angle and vertical depth of the inverted wedge-shaped trench; constructing a calculation logic for shear strengthening of the inverted wedge shear key, generating the total shear strength of the composite structure; acquiring the moisture characteristic curves of the backfill improved soil and the substrate sand, determining the air intake value and saturated hydraulic conductivity; determining the backfill thickness and particle size distribution of the improved soil layer, completing layered backfilling to construct a discontinuous capillary retardation interface; preset a safety factor threshold; collecting real-time monitoring data of the arid sandy land ecological terraces; obtaining stability assessment results, and generating corresponding irrigation control strategies or emergency drainage strategies based on the assessment results. This invention effectively solves the problem of insufficient shear strength caused by loose sandy substrate, significantly improving the slope's anti-sliding capacity and overall structural stability.

Description

Technical Field

[0001] This invention relates to the fields of ecological environment management and agricultural water and soil engineering technology, specifically a method for transforming ecological terraces in arid sandy land. Background Technology

[0002] In the current environment of ecological governance and agricultural development and utilization of arid and sandy land, the construction of terraces is the main means of realizing the transformation of land resources, which usually involves earthwork reshaping of sandy slopes to form planting surfaces.

[0003] Existing solutions generally employ simple slope leveling or surface soil replacement. Due to the dispersed particles and lack of cohesion in the matrix sand, its physical structure is loose, with limited internal friction angles and natural angles of repose. Traditional methods lack deep mechanical interlocking mechanisms and effective hydraulic impediment design, resulting in insufficient shear strength and poor water and fertilizer retention capacity of the slope. Under irrigation or rainfall conditions, the soil is highly susceptible to shear slippage and rapid water leakage. Furthermore, operation and maintenance rely heavily on passive maintenance, lacking real-time monitoring and dynamic control of moisture content, pore water pressure, and slope displacement, leading to repeated collapses and instability risks during the treatment process, making it difficult to maintain structural safety throughout the entire life cycle. Therefore, how to improve the shear strength and water retention of sandy soil through physical and mechanical reconstruction and hydraulic interface design, and establish an active stability control system to prevent recurrent landslides, has become an urgent technical problem to be solved. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides a method for transforming ecological terraces in arid sandy land. Specifically, the technical solution of the present invention includes:

[0005] Step 1: Obtain particle size distribution and shear characteristics data of the matrix sand, and determine the internal friction angle and natural angle of repose of the matrix through experiments; based on the internal friction angle and natural angle of repose of the matrix, determine the sidewall inclination angle and vertical depth of the inverted wedge groove; construct the shear strengthening calculation logic of the inverted wedge shear key, generate the total shear strength of the composite structure, and excavate and trim the inverted wedge groove on the dry sand slope according to the sidewall inclination angle and vertical depth of the inverted wedge groove;

[0006] Step 2: Obtain the moisture characteristic curves of the backfill improved topsoil and the matrix sand, and determine the air intake value and saturated hydraulic conductivity; based on the air intake value and saturated hydraulic conductivity, perform capillary resistance efficiency calculation to obtain the capillary resistance efficiency index; based on the capillary resistance efficiency index, determine the backfill thickness and particle size distribution of the improved topsoil layer, and complete the layered backfilling in the inverted wedge-shaped groove to construct a discontinuous capillary resistance interface.

[0007] Step 3: Preset safety factor threshold; collect real-time monitoring data of the arid sandy ecological terraces, including at least the topsoil moisture content, interfacial pore water pressure, and slope micro-displacement; calculate the real-time safety factor based on the real-time monitoring data using the life-cycle stability assessment logic; compare the real-time safety factor with the safety factor threshold to obtain the stability assessment result, and generate corresponding irrigation control strategies or emergency drainage strategies based on the assessment result.

[0008] Optionally, step one specifically includes:

[0009] S11. The internal friction angle and micro-cohesion of the matrix sand were collected by triaxial shear test, and the natural angle of repose of the matrix sand was determined by angle of repose meter.

[0010] S12. Determine the natural slip surface of the soil based on the internal friction angle of the matrix, and set the sidewall inclination angle and vertical depth of the inverted wedge-shaped groove, wherein the sidewall inclination angle is configured to be greater than the angle of the natural slip surface of the soil to form a forced interlocking.

[0011] S13. Based on the modified model of the Mohr-Coulomb failure criterion, the shear strengthening calculation of the inverted wedge shear key is performed. The geometric interlocking coefficient, which is determined in advance by finite element simulation inversion, is introduced to characterize the transmission efficiency of the soil compression modulus to the wedge effect. The additional shear component is maximized by optimizing the side wall inclination angle.

[0012] Optionally, in S13, the calculation logic for the total shear strength of the composite structure is as follows: multiply the normal stress generated by the overlying soil and crop load by the tangent of the internal friction angle of the matrix to obtain the first component; multiply twice the cohesion of the backfill improved soil by the vertical depth of the inverted wedge groove, and then divide by the distribution spacing of the shear keys along the slope to obtain the second component; multiply the normal stress, the geometric interlocking coefficient, and twice the sine of the sidewall inclination angle to obtain the third component; add the first, second, and third components to obtain the total shear strength of the composite structure.

[0013] Optionally, step two specifically includes:

[0014] S21. Measure the moisture characteristic curves of the backfill improved soil and the matrix sand, and obtain the saturated permeability coefficient of the backfill improved soil and the saturated permeability coefficient of the matrix sand.

[0015] S22. Based on the unsaturated soil seepage theory, a capillary resistance efficiency calculation model is established to quantify the ability of the backfill improved soil and the matrix sand to store water under unsaturated conditions by utilizing the suction difference generated by the particle size difference.

[0016] S23. Based on the capillary resistance efficiency calculation model, calculate the capillary resistance efficiency index, and adjust the particle size distribution of the backfill soil to change the pore size distribution index, so as to maximize the capillary resistance efficiency index within the crop water suction range.

[0017] Optionally, in S23, the calculation logic for the capillary resistance efficiency index is as follows: First, calculate the numerator, which is the product of the saturated permeability coefficient of the backfill improved soil and the power function of the effective saturation degree of the soil, where the exponent of the power function of the effective saturation degree of the soil is the pore size distribution index of the backfill improved soil; second, calculate the denominator, which is the product of the saturated permeability coefficient of the matrix sand and the power function of the effective saturation degree of the sand, where the exponent of the power function of the effective saturation degree of the sand is the pore size distribution index of the matrix sand; finally, calculate the common logarithm of the ratio of the numerator to the denominator to obtain the capillary resistance efficiency index.

[0018] Among them, the pore size distribution index is obtained in advance by fitting the particle size distribution curve, and the effective saturation is calculated by substituting the matrix suction at the current interface into the moisture characteristic curve equation.

[0019] Optionally, the method may also include steps for gravitational potential energy dissipation and steady-state control of the flow field, specifically including:

[0020] S41. Based on the terrace slope and the design flood peak flow, calculate the distribution of potential energy and shear force along the flow path;

[0021] S42. Construct a continuous labyrinth-type energy dissipation structure at the bottom of the water conveyance canal. The labyrinth-type energy dissipation structure includes several waterfall units arranged in a fish-scale pit pattern.

[0022] S43. Based on the principle of energy density conservation and the theory of turbulent dissipation, perform dynamic calculations on the labyrinth-type energy dissipation structure to determine the energy dissipation density of a single-stage waterfall, and adjust the height and density of the single-stage waterfall unit so that the outflow velocity is lower than the critical non-scouring velocity of the soil.

[0023] Optionally, in S43, the calculation logic for the energy dissipation density of a single-stage waterfall is as follows: multiply the fluid density, the square of the unit inflow velocity, and the comprehensive energy dissipation coefficient determined in advance through fluid dynamics simulation, and divide by two to obtain the kinetic energy dissipation term; multiply the fluid density, gravitational acceleration, the height of the single-stage waterfall, and the preset potential energy dissipation efficiency coefficient to obtain the potential energy dissipation term; add the kinetic energy dissipation term and the potential energy dissipation term to obtain the energy dissipation density.

[0024] The calculation logic for the outflow velocity is as follows: the sum of the square of the inflow velocity of the calculation unit and twice the gravitational acceleration multiplied by the height of the single-stage drop, minus twice the energy dissipation density divided by the fluid density, and the square root of the difference is taken to obtain the outflow velocity.

[0025] Optionally, step three specifically includes:

[0026] S31. Real-time collection of moisture content, interfacial pore water pressure and slope micro-displacement of backfill improved soil layer.

[0027] S32. Based on the infinite slope stability analysis method and the effective stress principle, perform a full life cycle stability assessment;

[0028] S33. Calculate the permeation stress components parallel to the slope surface, and combine them with the total shear strength of the composite structure generated in step one to calculate the real-time safety factor that varies with time.

[0029] The calculation logic for the real-time safety factor is as follows: Calculate the anti-sliding force term, which is the total shear strength minus the product of the interfacial pore water pressure and the tangent of the matrix internal friction angle; calculate the sliding force term, which is the product of the soil wet density, gravitational acceleration, vertical thickness of the soil layer above the sliding surface, the cosine of the terrace slope angle, and the sine of the terrace slope angle, plus the seepage stress component; divide the anti-sliding force term by the sliding force term to obtain the real-time safety factor.

[0030] Optionally, step three also includes evaluating the real-time safety factor to obtain the first prediction result. The specific logic includes:

[0031] When the real-time safety factor is greater than 1.5, the system is determined to be in a steady state, and the stability assessment result is labeled as safe.

[0032] When the real-time safety factor is greater than 1.2 and less than or equal to 1.5, the system is determined to be in an early warning state, and the stability assessment result is labeled as a risk warning.

[0033] S34. Extract the irrigation control strategies corresponding to the risk warning labels. The irrigation control strategies include suspending irrigation operations on the ecological terraces in arid sandy areas.

[0034] Optionally, step three also includes evaluating the real-time safety factor to obtain a second prediction result, the specific logic of which includes:

[0035] When the real-time safety factor is less than or equal to 1.2, the system is determined to be in a critical unstable state, and the stability assessment result is labeled as dangerous.

[0036] S35. Extract the emergency drainage strategy corresponding to the hazard label. The emergency drainage strategy includes automatically opening the emergency overflow valve for rapid pressure relief and using the bypass channel to discharge supersaturated water to reduce the interfacial pore water pressure.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. This invention constructs an inverted wedge-shaped shear key structure and utilizes the geometric feature that the inclination angle of the sidewall is greater than that of the natural slip surface of the soil to achieve forced interlocking and mechanical reconstruction of the soil. This design transforms the shear displacement of the soil into normal compression, stimulates the shear dilatation effect of the soil, effectively solves the problem of insufficient shear strength caused by the loose matrix of sandy soil, and significantly improves the anti-slip capacity and overall structural stability of the slope.

[0039] 2. This invention constructs a discontinuous capillary retardation interface based on the theory of unsaturated soil seepage, and utilizes the difference in particle size between the improved topsoil and the substrate sand to generate suction difference; by calculating the capillary retardation efficiency index to optimize the topsoil gradation and backfill thickness, the water is effectively locked in the crop root layer in an unsaturated state, which overcomes the technical problem of water leakage and fertilizer retention in arid sandy land, greatly improves water resource utilization efficiency and realizes active regulation of soil moisture.

[0040] 3. This invention establishes a closed-loop control system for stability throughout the entire life cycle. By monitoring the water content, pore water pressure, and slope micro-displacement in real time, the system dynamically calculates the real-time safety factor. Based on the evaluation results, the system automatically executes strategies such as suspending irrigation or opening the emergency overflow valve to release pressure, realizing the transformation from passive maintenance to active intervention. This effectively avoids the risk of sudden landslides caused by excessive pore water pressure and ensures the long-term safe operation of the terraced fields.

[0041] 4. This invention introduces a labyrinth-type energy dissipation structure into the water conveyance system. The fish-scale pit-shaped drop unit induces the water flow to generate swirling to dissipate the kinetic energy of the flood peak. Combining the energy density conservation and turbulent dissipation theory, the outflow velocity is precisely controlled to keep it below the critical non-scouring velocity of the soil, ensuring the integrity of the terrace structure under extreme rainfall conditions and effectively preventing soil erosion caused by high-speed water flow. Attached Figure Description

[0042] The present invention will be further explained below with reference to the accompanying drawings and embodiments:

[0043] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0045] Example 1:

[0046] Please see Figure 1 A method for transforming ecological terraces in arid sandy land, the specific steps of which include:

[0047] Step 1: Obtain particle size distribution and shear characteristics data of the matrix sand, and determine the internal friction angle and natural angle of repose of the matrix through experiments; based on the internal friction angle and natural angle of repose of the matrix, determine the sidewall inclination angle and vertical depth of the inverted wedge groove; construct the shear strengthening calculation logic of the inverted wedge shear key, generate the total shear strength of the composite structure, and excavate and trim the inverted wedge groove on the dry sand slope according to the sidewall inclination angle and vertical depth of the inverted wedge groove;

[0048] Step 2: Obtain the moisture characteristic curves of the backfill improved topsoil and the matrix sand, and determine the air intake value and saturated hydraulic conductivity; based on the air intake value and saturated hydraulic conductivity, perform capillary resistance efficiency calculation to obtain the capillary resistance efficiency index; based on the capillary resistance efficiency index, determine the backfill thickness and particle size distribution of the improved topsoil layer, and complete the layered backfilling in the inverted wedge-shaped groove to construct a discontinuous capillary resistance interface.

[0049] Step 3: Preset safety factor threshold; collect real-time monitoring data of the arid sandy ecological terraces, including at least the topsoil moisture content, interfacial pore water pressure, and slope micro-displacement; calculate the real-time safety factor based on the real-time monitoring data using the life-cycle stability assessment logic; compare the real-time safety factor with the safety factor threshold to obtain the stability assessment result, and generate corresponding irrigation control strategies or emergency drainage strategies based on the assessment result.

[0050] This embodiment provides a method for transforming ecological terraces in arid sandy land. This method aims to solve the technical problems of loose soil structure, poor water retention capacity and insufficient slope stability in the construction of existing arid sandy land terraces. This embodiment constructs an adaptive ecological terrace system through mechanical reconstruction of physical structure, hydraulic interface resistance design and closed-loop monitoring throughout the entire cycle.

[0051] Step 1: Construction of the mechanical interlocking model and structural remodeling of the inverted wedge-shaped shear key

[0052] Obtain particle size distribution and shear properties data of matrix sand; determine the internal friction angle and natural angle of repose of the matrix through experiments; the internal friction angle of the matrix refers to the measure of the maximum shear capacity generated by the mutual friction and interlocking between particles inside the soil, which is obtained from triaxial shear tests; the natural angle of repose refers to the maximum slope angle that can maintain natural stability when loose sand is piled up, which is obtained from the measurement of the angle of repose instrument.

[0053] Based on the above parameters, the sidewall inclination angle and vertical depth of the inverted wedge-shaped groove are determined; the shear strengthening calculation logic of the inverted wedge shear key is constructed to generate the total shear strength of the composite structure; according to the calculated sidewall inclination angle and vertical depth, the inverted wedge-shaped groove is excavated and trimmed on the arid sandy slope; the core of this step is to use the geometric characteristics of the inverted wedge structure to convert the shear displacement of the soil into normal compression, thereby generating additional resistance;

[0054] Step 2: Construction of discontinuous capillary retardation interfaces

[0055] Obtain the moisture characteristic curves of the backfill improved topsoil and the matrix sand to determine the air intake value and saturated hydraulic conductivity; the moisture characteristic curve SWCC describes the relationship between soil moisture content and matrix suction; the air intake value refers to the critical suction value when air begins to enter the saturated soil pores and replace water.

[0056] Based on the air intake value and saturated hydraulic conductivity, capillary resistance efficiency is calculated to obtain the capillary resistance efficiency index. Based on this index, the backfill thickness and particle size distribution of the improved topsoil layer are determined, and layered backfilling is completed in the inverted wedge-shaped groove. This step aims to utilize the particle size difference between the backfill topsoil and the substrate sand to construct a discontinuous capillary resistance interface, locking water in the crop root layer under unsaturated conditions.

[0057] Step 3: Closed-loop regulation of life-cycle stability

[0058] Preset a safety factor threshold; collect real-time monitoring data of arid sandy ecological terraces, including at least the topsoil moisture content, interfacial pore water pressure, and slope micro-displacement; use the life-cycle stability assessment logic to calculate the real-time safety factor based on the real-time monitoring data; compare the real-time safety factor with the safety factor threshold to obtain the stability assessment result, and generate corresponding irrigation control strategies or emergency drainage strategies based on the assessment result.

[0059] Through the synergistic effect of the above three steps, this scheme achieves forced soil interlocking using an inverted wedge structure in terms of mechanics, significantly improving shear strength; solves the problem of water leakage and fertilizer retention in sandy areas by utilizing capillary resistance effect in terms of hydraulics; and achieves proactive intervention in the stability of terraced fields through real-time monitoring and feedback in terms of management, thereby completely changing the situation of repeated collapses in traditional sandy land management.

[0060] Example 2:

[0061] Step one specifically includes:

[0062] S11. The internal friction angle and micro-cohesion of the matrix sand were collected by triaxial shear test, and the natural angle of repose of the matrix sand was determined by angle of repose meter.

[0063] S12. Determine the natural slip surface of the soil based on the internal friction angle of the matrix, and set the sidewall inclination angle and vertical depth of the inverted wedge-shaped groove, wherein the sidewall inclination angle is configured to be greater than the angle of the natural slip surface of the soil to form a forced interlocking.

[0064] S13. Based on the modified model of the Mohr-Coulomb failure criterion, the shear strengthening calculation of the inverted wedge shear key is performed. The geometric interlocking coefficient, which is determined in advance by finite element simulation inversion, is introduced to characterize the transmission efficiency of the soil compression modulus to the wedge effect. The additional shear component is maximized by optimizing the side wall inclination angle.

[0065] This embodiment further specifies step one, and describes in detail the logic of parameter acquisition and structural design;

[0066] S11, Analysis of matrix physical parameters

[0067] The internal friction angle of the matrix sand was collected by triaxial shear test. With small cohesive forces Simultaneously, the natural angle of repose of the matrix sand was measured using an angle of repose meter. These parameters form the physical basis for subsequent geometric design.

[0068] S12, Geometric Interlocking Structure Design

[0069] Based on the internal friction angle of the matrix Determine the natural slip surface of the soil; set the inclination angle of the sidewalls of the inverted wedge-shaped groove. With vertical depth ;

[0070] In this embodiment, the sidewall inclination angle It is configured with an angle greater than the angle of the soil's natural slip surface; the purpose of this design is to break the natural equilibrium state of the soil and form a forced interlock; the specific correlation logic is: the internal friction angle of the matrix determines the natural slip surface of the soil, and the geometric design of the inverted wedge groove must break through this natural slip angle so that the soil must overcome additional geometric resistance when shearing tends to occur.

[0071] S13, Shear Key Shear Strengthening Calculation

[0072] A modified model based on the Mohr-Coulomb failure criterion was used to perform shear strengthening calculations for inverted wedge shear keys. In this calculation, a geometric engagement coefficient, pre-determined through finite element simulation inversion, was introduced. ;

[0073] The specific steps of finite element simulation inversion include: establishing a two-dimensional plane strain numerical model of the inverted wedge shear key, in which the soil constitutive relation adopts a hardened soil model or a modified Mohr-Coulomb model; and applying normal stresses of different gradients at the top of the model. Simulate overburden load; simulate soil shear displacement process, extract the normal stress increment distribution on the shear surface; calculate the ratio of the normal stress caused by theoretical geometric expansion to the actual normal stress obtained from the simulation, and fit this ratio to a dimensionless geometric engagement coefficient. ;

[0074] Geometric bite coefficient It is a dimensionless parameter used to characterize the efficiency of soil compression modulus in transmitting the wedge effect; by introducing this coefficient and optimizing the sidewall inclination angle... The recommended optimization scope is: This can maximize the additional shear resistance component;

[0075] By quantifying the matrix parameters and introducing the geometric interlocking coefficient, an inverted wedge-shaped groove structure that conforms to both the principle of mechanical strengthening and the economic efficiency of engineering can be precisely designed, ensuring that the soil dilatation effect can be effectively activated, thereby significantly improving the slope's anti-sliding capacity.

[0076] Example 3:

[0077] In S13, the calculation logic for the total shear strength of the composite structure is as follows: multiply the normal stress generated by the overlying soil and crop load by the tangent of the matrix internal friction angle to obtain the first component; multiply twice the cohesion of the backfill improved soil by the vertical depth of the inverted wedge groove, and then divide by the distribution spacing of the shear keys along the slope to obtain the second component; multiply the normal stress, the geometric interlocking coefficient, and twice the sine of the sidewall inclination angle to obtain the third component; add the first, second, and third components to obtain the total shear strength of the composite structure.

[0078] This embodiment elaborates in detail the specific calculation logic of the total shear strength of the composite structure in step S13;

[0079] To quantify the effect of the inverted wedge structure on improving the shear strength of the soil, this embodiment constructs the total shear strength of the composite structure. The calculation model is based on classical soil mechanics shear strength theory and incorporates the mechanical wedge self-locking principle to calculate the total shear strength. The calculation formula is as follows:

[0080]

[0081] in, Normal stress, measured in Pascals (Pa); its value is derived from field calculations of the overlying soil and crop loads; in the life-cycle stability assessment, this normal stress... Defined as a time-varying variable Its value is updated in real time according to the change in the moisture content of the topsoil layer, and the calculation logic is as follows: This reflects the effect of soil weight gain caused by rainfall infiltration on enhancing frictional resistance; it is one of the main driving forces causing soil shear slip, and also the source of normal pressure that generates frictional resistance.

[0082] : Internal friction angle of the matrix, in radians (rad); its value is derived from triaxial shear tests in geological surveys;

[0083] : Cohesion of backfill improved soil, in Pascals (Pa); its value is derived from experimental data of improved soil;

[0084] The vertical depth of the inverted wedge groove, in meters (m); its value is derived from design parameters.

[0085] : The spacing of shear keys along the slope, in meters (m); its value is derived from design parameters;

[0086] Geometric interlocking coefficient, dimensionless; its value is derived from finite element simulation inversion and is used to correct the difference between the theoretical wedge effect and the actual soil deformation; during inversion, the compression modulus of the matrix sand is used. Poisson's ratio and the inclination angle of the sidewall of the inverted wedge groove As input variables, a least squares regression analysis was used to establish... and The functional relationship is used to quantify the attenuation effect of soil stiffness on the transmission of wedge forces;

[0087] The inverted wedge groove sidewall inclination angle is the angle between the sidewall and the vertical line, measured in radians (rad). Its value is a geometric variable used for design optimization.

[0088] First component : Represents the frictional resistance of the matrix sand itself, following the traditional Mohr-Coulomb criterion;

[0089] Second component : Represents the cohesion contribution provided by the improved backfill soil; by integrating the cohesion along the depth and distributing it evenly across the shear key spacing, the improvement of the overall strength by the improved soil is quantified.

[0090] Third component This represents the additional wedge effect produced by the inverted wedge structure; when the overlying soil is under pressure, the inverted wedge geometry forces the soil to undergo shear dilatation during shearing, transforming the vertical load into normal compression. The term is used to maximize this component;

[0091] This computational model no longer relies solely on surface friction. Instead, by introducing a second and third component, it explicitly calculates the contributions of improved soil cohesion and wedge geometry effects, enabling accurate prediction of the shear strength of composite soils and providing a reliable quantitative basis for engineering design.

[0092] Example 4:

[0093] Step two specifically includes:

[0094] S21. Measure the moisture characteristic curves of the backfill improved soil and the matrix sand, and obtain the saturated permeability coefficient of the backfill improved soil and the saturated permeability coefficient of the matrix sand.

[0095] S22. Based on the unsaturated soil seepage theory, a capillary resistance efficiency calculation model is established to quantify the ability of the backfill improved soil and the matrix sand to store water under unsaturated conditions by utilizing the suction difference generated by the particle size difference.

[0096] S23. Based on the capillary resistance efficiency calculation model, calculate the capillary resistance efficiency index, and adjust the particle size distribution of the backfill soil to change the pore size distribution index, so as to maximize the capillary resistance efficiency index within the crop water suction range.

[0097] This embodiment further specifies step two, and describes in detail the design logic of the discontinuous capillary retardation interface.

[0098] S21, Hydraulic parameter determination

[0099] The saturated permeability coefficient (SWCC) of the backfill improved topsoil and the matrix sand was determined; from this, the saturated permeability coefficient of the backfill improved topsoil was obtained. Saturated permeability coefficient of matrix sand ;

[0100] S22. Establishment of the capillary resistance model

[0101] Based on the theory of unsaturated soil seepage, a calculation model for capillary resistance efficiency is established.

[0102] The purpose of this model is to quantify the ability of the backfill soil to store water under unsaturated conditions by utilizing the suction difference generated by the difference in particle size between the fine particles of the backfill soil and the coarse particles of the substrate sand. Under unsaturated conditions, the suction of the fine-particle soil is much greater than that of the coarse-particle soil, and water is locked in the fine-particle layer by capillary force until the suction drops to the threshold value.

[0103] S23, Parameter Optimization and Gradation Adjustment

[0104] Based on the capillary resistance efficiency calculation model, the capillary resistance efficiency index is calculated; and the particle size distribution of the backfill soil is adjusted to change the pore size distribution index, so that the capillary resistance efficiency index is maximized within the crop water suction range; this step realizes the transformation from passive water blocking to active regulation.

[0105] By accurately measuring and calculating hydraulic parameters, the optimal soil structure can be designed to maximize the retention time of water in the crop root zone, thus greatly improving the water resource utilization efficiency in arid and sandy areas.

[0106] Example 5:

[0107] In S23, the calculation logic of the capillary resistance efficiency index is as follows: First, calculate the numerator, which is the product of the saturated permeability coefficient of the backfill improved soil and the power function of the effective saturation degree of the soil, where the exponent of the power function of the effective saturation degree of the soil is the pore size distribution index of the backfill improved soil; second, calculate the denominator, which is the product of the saturated permeability coefficient of the matrix sand and the power function of the effective saturation degree of the sand, where the exponent of the power function of the effective saturation degree of the sand is the pore size distribution index of the matrix sand; finally, calculate the common logarithm of the ratio of the numerator to the denominator to obtain the capillary resistance efficiency index.

[0108] The pore size distribution index is obtained in advance by fitting the particle size distribution curve, and the effective saturation is calculated by substituting the matrix suction at the current interface into the moisture characteristic curve equation. This embodiment elaborates on the specific calculation logic of the capillary resistance efficiency index in step S23;

[0109] To evaluate the water retention capacity of different soil layer combinations, this embodiment introduces the capillary retention efficiency index. This index is derived from the Richards equation and a simplified derivation of the unsaturated soil permeability coefficient function; it is the capillary resistance efficiency index. The calculation formula is as follows:

[0110]

[0111] in, , : These represent the saturated permeability coefficients of the backfill improved topsoil and the matrix sand, respectively, in meters per second (m / s); their values ​​are derived from constant head permeability tests.

[0112] , : Represents the matrix suction at the current interface. Below, the effective saturation of the topsoil and sand; this is a dimensionless value of 0-1; its value is determined by the current suction force. The moisture characteristic curve equations for each material are substituted into the equations for calculation. Specifically, the Brooks-Corey model is used for the moisture characteristic curve equations, and its mathematical expression is as follows:

[0113] when hour, ;

[0114] when hour, ;

[0115] in This is the intake air value. The pore size distribution index is derived from the moisture characteristic curve data obtained in step two. To follow the matrix suction The effective saturation function is changing.

[0116] , : These represent the pore size distribution indices of the backfill improved topsoil and the matrix sand, respectively, and are dimensionless; their values ​​are obtained in advance based on the particle size distribution curve fitting.

[0117] : Matrix suction at the interface, in kilopascals (kPa), is a continuous variable at the interface;

[0118] Numerator calculation: Calculate the unsaturated permeability coefficient of the backfill improved soil, i.e. ;

[0119] Denominator calculation: Calculate the unsaturated permeability coefficient of the matrix sand, i.e. ;

[0120] Exponent generation: The commonly used logarithm for calculating the ratio of the numerator to the denominator;

[0121] This index intuitively reflects the difference in hydraulic conductivity on both sides of the interface; when At higher levels, This indicates that moisture is effectively trapped in the topsoil layer; when When the exponent decreases near saturation, drainage is permitted; this formula provides a clear mathematical optimization objective for the selection and gradation design of topsoil materials.

[0122] Example 6:

[0123] The method also includes steps for gravitational potential energy dissipation and steady-state control of the flow field, specifically including:

[0124] S41. Based on the terrace slope and the design flood peak flow, calculate the distribution of potential energy and shear force along the flow path;

[0125] S42. Construct a continuous labyrinth-type energy dissipation structure at the bottom of the water conveyance canal. The labyrinth-type energy dissipation structure includes several waterfall units arranged in a fish-scale pit pattern.

[0126] S43. Based on the principle of energy density conservation and the theory of turbulent dissipation, perform dynamic calculations on the labyrinth-type energy dissipation structure to determine the energy dissipation density of a single-stage waterfall, and adjust the height and density of the single-stage waterfall unit so that the outflow velocity is lower than the critical non-scouring velocity of the soil.

[0127] Based on the above static modification, this embodiment further adds dynamic control steps for rainstorm conditions, namely gravitational potential energy dissipation and steady-state control of the flow field.

[0128] S41, Flow Field Energy Analysis

[0129] According to the terraced slope With design peak flow Calculate the potential energy and shear force distribution along the flow path; this is to determine the scouring and destructive forces that the water flow may produce on the soil.

[0130] S42, Energy dissipation structure construction

[0131] A continuous labyrinthine energy dissipation structure is constructed at the bottom of the water conveyance channel; this structure includes several drop units arranged in a fish-scale pit pattern; the fish-scale pit pattern can induce local hydraulic jumps and swirls in the water flow, thereby increasing energy dissipation.

[0132] S43, Dynamic Calculation and Structural Optimization

[0133] Based on the principle of energy density conservation and the theory of turbulent dissipation, dynamic calculations were performed on a labyrinthine energy dissipation structure. These calculations relied on a CFD fluid simulation platform, and the simulation model employed an RNG model. Using both turbulence and VOF multiphase flow models, the inlet boundary condition is set to the velocity corresponding to the design peak flow, and the wall boundary condition is a no-slip wall. The energy dissipation density of a single-stage drop structure is determined; the height of the single-stage drop structure is adjusted. With density This results in the outflow velocity after energy dissipation. Below the critical non-scouring velocity of the soil ;

[0134] By actively constructing a maze-shaped energy dissipation structure, the destructive kinetic energy of the flood peak is converted into heat energy and dissipated, ensuring the structural integrity of the terraced water conveyance system under extreme rainfall conditions and preventing soil erosion caused by water flow.

[0135] Example 7:

[0136] In S43, the calculation logic for the energy dissipation density of a single-stage waterfall is as follows: multiply the fluid density, the square of the unit inflow velocity, and the comprehensive energy dissipation coefficient determined in advance through fluid dynamics simulation, and divide by two to obtain the kinetic energy dissipation term; multiply the fluid density, gravitational acceleration, the height of the single-stage waterfall, and the preset potential energy dissipation efficiency coefficient to obtain the potential energy dissipation term; add the kinetic energy dissipation term and the potential energy dissipation term to obtain the energy dissipation density.

[0137] The calculation logic for the outflow velocity is as follows: the sum of the square of the inflow velocity of the calculation unit and twice the gravitational acceleration multiplied by the height of the single-stage drop, minus twice the energy dissipation density divided by the fluid density, and the square root of the difference is taken to obtain the outflow velocity.

[0138] This embodiment elaborates in detail the specific calculation logic of energy dissipation density and outflow velocity in step S43;

[0139] A potential energy dissipation efficiency coefficient is introduced, and the potential energy dissipation term is obtained by multiplying the fluid density, gravitational acceleration, single-stage drop height and the potential energy dissipation efficiency coefficient. The potential energy dissipation efficiency coefficient is 0.7-0.9 and is used to characterize the proportion of potential energy converted into turbulent heat energy during the drop process.

[0140] To precisely control the water flow velocity, this embodiment establishes a calculation model based on energy density conservation, and calculates the energy dissipation density of a single-stage waterfall. The calculation formula is as follows:

[0141]

[0142] in, The potential energy dissipation efficiency coefficient; Energy dissipation density, measured in Pascals (Pa) or Joules per cubic meter (J / m³).

[0143] Fluid density, in kilograms per cubic meter (kg / m³);

[0144] Unit inflow velocity, in meters per second (m / s);

[0145] The comprehensive energy dissipation coefficient is dimensionless (0-1). This coefficient is related to the depth-to-width ratio and arrangement of the fish-scale pits, and its value is derived from CFD fluid dynamics simulation. The specific acquisition logic is as follows: extract the total energy at the inlet section of the drop structure from the simulation results. Total energy of the outlet section Calculate the energy difference Based on the kinetic energy dissipation formula Inverse solution yields This characterizes the turbulent dissipation efficiency under a specific fish-scale pit arrangement.

[0146] Gravitational acceleration, measured in meters per second squared (m / s²).

[0147] Single-stage drop height, in meters (m), derived from design parameters;

[0148] In this formula, the first term The term representing kinetic energy dissipation mainly originates from vortex viscous dissipation and impact dissipation; the second term... Represents the potential energy dissipation term, outflow velocity The calculation formula is as follows:

[0149]

[0150] This formula calculates the initial kinetic energy and Related plus potential energy increment Subtract the energy dissipated by the structure. The remaining energy is converted into outflow velocity;

[0151] Using this calculation model, engineers can work backwards to derive the requirements for non-scouring. The required drop height and pit density enable precise quantitative design of the energy dissipation structure, avoiding insufficient or excessive energy dissipation caused by construction based on experience.

[0152] Example 8:

[0153] Step three specifically includes:

[0154] S31. Real-time collection of moisture content, interfacial pore water pressure and slope micro-displacement of backfill improved soil layer.

[0155] S32. Based on the infinite slope stability analysis method and the effective stress principle, perform a full life cycle stability assessment;

[0156] S33. Calculate the permeation stress components parallel to the slope surface, and combine them with the total shear strength of the composite structure generated in step one to calculate the real-time safety factor that varies with time.

[0157] The calculation logic for the real-time safety factor is as follows: Calculate the anti-sliding force term, which is the total shear strength minus the product of the interfacial pore water pressure and the tangent of the matrix internal friction angle; calculate the sliding force term, which is the product of the soil wet density, gravitational acceleration, vertical thickness of the soil layer above the sliding surface, the cosine of the terrace slope angle, and the sine of the terrace slope angle, plus the seepage stress component; divide the anti-sliding force term by the sliding force term to obtain the real-time safety factor.

[0158] This embodiment further specifies step three, and describes in detail the parameter acquisition and calculation logic of the whole life cycle stability assessment.

[0159] S31, Multidimensional Status Monitoring

[0160] Real-time collection of moisture content of the backfilled and improved topsoil layer Interfacial pore water pressure and slope micro-displacement These data were acquired through a pre-embedded sensor array, forming the data foundation for stability assessment. Preprocessing operations were performed on the collected raw data, including: using a moving average filtering algorithm to remove high-frequency noise interference from the water content and pore water pressure data; and using a 3D model to filter out the slope micro-displacement data. The criteria eliminate abnormal mutation values ​​to ensure that the data input into subsequent calculation models has temporal continuity and authenticity;

[0161] S32. Evaluation Methodology

[0162] Based on the infinite slope stability analysis method and the effective stress principle, a full life cycle stability assessment is performed.

[0163] S33, Stress Component Calculation

[0164] Calculate the seepage stress components parallel to the slope surface The calculation formula is: ,in The density of water, For real-time moisture content, Residual moisture content This represents the saturated moisture content.

[0165] Simultaneously, update the normal stress term in the total shear strength of the composite structure, replacing the static normal stress in step one. Replace with real-time normal stress ;

[0166] Calculate the real-time safety factor as it changes over time by combining the updated real-time total shear strength. ;

[0167] S34, Real-time safety factor calculation logic

[0168] Real-time security factor The calculation formula is as follows:

[0169]

[0170] Among them, the numerator term, the anti-slip force term, is composed of the total shear strength. Subtract the shear strength reduction term caused by pore water pressure ;in Sourced from real-time monitoring;

[0171] The denominator term, the sliding force term, consists of two parts; the first part is the sliding force generated by gravity, i.e., the wet density of the soil. Gravitational acceleration Vertical thickness of soil layer above slip surface With the sine value of the terrace slope angle The product of the four components; the second part is the component of seepage stress generated by the seepage flow. ;

[0172] Soil wet density varies with real-time moisture content;

[0173] Vertical soil thickness, i.e., the thickness of the soil layer in the direction of gravity, is derived from design parameters;

[0174] Terraced field slope angle, in radians (rad).

[0175] This formula dynamically couples mechanical parameters. Hydraulic parameters , and physical parameters It can reflect subtle changes in slope stability in real time during rainfall or irrigation, providing a precise mathematical basis for subsequent intelligent decision-making.

[0176] Example 9:

[0177] Step three also includes evaluating the real-time safety factor to obtain the first prediction result. The specific logic includes:

[0178] When the real-time safety factor is greater than 1.5, the system is determined to be in a steady state, and the stability assessment result is labeled as safe.

[0179] When the real-time safety factor is greater than 1.2 and less than or equal to 1.5, the system is determined to be in an early warning state, and the stability assessment result is labeled as a risk warning.

[0180] The aforementioned safety factor thresholds of 1.5 and 1.2 are determined based on the grading standards for the stability of special geological slopes in the "Technical Specification for Slope Engineering" (GB 50330-2013), combined with the measured shear strength values ​​of the inverted wedge shear key composite structure of this invention. Specifically, the safety factor threshold of 1.5 corresponds to the upper limit when the soil is in a fully elastic deformation stage and has sufficient reserve strength, while the safety factor threshold of 1.2 corresponds to the lower limit when the soil enters the plastic yield critical point and seepage stress begins to dominate the slope displacement. This correspondence is verified through regression analysis of triaxial shear test data and slope micro-displacement monitoring curves under different moisture content conditions, ensuring the consistency between system state discrimination and mechanical response characteristics.

[0181] S34. Extract the irrigation control strategies corresponding to the risk warning labels. The irrigation control strategies include suspending irrigation operations on the ecological terraces in arid sandy areas.

[0182] This embodiment details the first-stage evaluation logic and response strategies based on the real-time security factor;

[0183] When the calculated real-time safety factor When the system is in a steady state, the stability assessment result is labeled as safe, and the system continues to operate normally.

[0184] When the real-time security factor When the system is in an early warning state, the stability assessment result is labeled as a risk warning.

[0185] Once a risk warning label is triggered, the system automatically extracts the corresponding irrigation control strategy; this strategy includes suspending irrigation operations on arid sandy ecological terraces.

[0186] By setting early warning intervals, the system can identify potential risks such as excessive pore pressure or excessive soil weight before the slope becomes truly unstable, and take measures such as suspending irrigation—a low-cost, high-response measure—to cut off the hydraulic driving factors that induce landslides at the source, thus achieving preventive maintenance.

[0187] Example 10:

[0188] Step three also includes evaluating the real-time safety factor to obtain a second prediction result. The specific logic includes:

[0189] When the real-time safety factor is less than or equal to 1.2, the system is determined to be in a critical unstable state, and the stability assessment result is labeled as dangerous.

[0190] S35. Extract the emergency drainage strategy corresponding to the hazard label. The emergency drainage strategy includes automatically opening the emergency overflow valve for rapid pressure relief and using the bypass channel to discharge supersaturated water to reduce the interfacial pore water pressure.

[0191] This embodiment details the second-stage danger assessment logic and response strategy based on the real-time safety factor;

[0192] When the real-time security factor When the system is in a critical unstable state, the stability assessment result is labeled as dangerous.

[0193] Once a hazard label is triggered, the system retrieves the corresponding emergency drainage strategy; this strategy includes automatically opening the emergency overflow valve for rapid pressure relief and using the bypass channel to discharge supersaturated water.

[0194] When preventative measures such as suspending irrigation fail to stop the safety factor from continuing to decline, the system can escalate its response level and directly reduce the interfacial pore water pressure through a physical drainage mechanism using an overflow valve. According to the foregoing Calculation formula, reduce This will directly increase the size of the anti-sliding force term, thereby rapidly increasing the safety factor and preventing catastrophic landslides.

[0195] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for reconstructing an ecological terrace in a dry sand land, characterized by, The specific steps include: Step 1: Obtain particle size distribution and shear characteristics data of the matrix sand, and determine the internal friction angle and natural angle of repose of the matrix through experiments; based on the internal friction angle and natural angle of repose of the matrix, determine the sidewall inclination angle and vertical depth of the inverted wedge groove; construct the shear strengthening calculation logic of the inverted wedge shear key, generate the total shear strength of the composite structure, and excavate and trim the inverted wedge groove on the dry sand slope according to the sidewall inclination angle and vertical depth of the inverted wedge groove; Step 2: Obtain the moisture characteristic curves of the backfill improved topsoil and the matrix sand, and determine the air intake value and saturated hydraulic conductivity; based on the air intake value and saturated hydraulic conductivity, perform capillary resistance efficiency calculation to obtain the capillary resistance efficiency index; based on the capillary resistance efficiency index, determine the backfill thickness and particle size distribution of the improved topsoil layer, and complete the layered backfilling in the inverted wedge-shaped groove to construct a discontinuous capillary resistance interface. Step 3: Preset safety factor threshold; collect real-time monitoring data of the arid sandy ecological terraces, including at least the topsoil moisture content, interfacial pore water pressure, and slope micro-displacement; calculate the real-time safety factor based on the real-time monitoring data using the life-cycle stability assessment logic; compare the real-time safety factor with the safety factor threshold to obtain the stability assessment result, and generate corresponding irrigation control strategies or emergency drainage strategies based on the assessment result.

2. The method for transforming ecological terraces in arid sandy land according to claim 1, characterized in that, Step one specifically includes: S11. The internal friction angle and micro-cohesion of the matrix sand were collected by triaxial shear test, and the natural angle of repose of the matrix sand was determined by angle of repose meter. S12. Determine the natural slip surface of the soil based on the internal friction angle of the matrix, and set the sidewall inclination angle and vertical depth of the inverted wedge-shaped groove, wherein the sidewall inclination angle is configured to be greater than the angle of the natural slip surface of the soil to form a forced interlocking. S13. Based on the modified model of the Mohr-Coulomb failure criterion, the shear strengthening calculation of the inverted wedge shear key is performed. The geometric interlocking coefficient, which is determined in advance by finite element simulation inversion, is introduced to characterize the transmission efficiency of the soil compression modulus to the wedge effect. The additional shear component is maximized by optimizing the side wall inclination angle.

3. The method for transforming ecological terraces in arid sandy land according to claim 2, characterized in that, In S13, the calculation logic for the total shear strength of the composite structure is as follows: multiply the normal stress generated by the overlying soil and crop load by the tangent of the matrix internal friction angle to obtain the first component; multiply twice the cohesion of the backfill improved soil by the vertical depth of the inverted wedge groove, and then divide by the distribution spacing of the shear keys along the slope to obtain the second component; multiply the normal stress, the geometric interlocking coefficient, and twice the sine of the sidewall inclination angle to obtain the third component; add the first, second, and third components to obtain the total shear strength of the composite structure.

4. The method for transforming ecological terraces in arid sandy land according to claim 1, characterized in that, Step two specifically includes: S21. Measure the moisture characteristic curves of the backfill improved soil and the matrix sand, and obtain the saturated permeability coefficient of the backfill improved soil and the saturated permeability coefficient of the matrix sand. S22. Based on the unsaturated soil seepage theory, a capillary resistance efficiency calculation model is established to quantify the ability of the backfill improved soil and the matrix sand to store water under unsaturated conditions by utilizing the suction difference generated by the particle size difference. S23. Based on the capillary resistance efficiency calculation model, calculate the capillary resistance efficiency index, and adjust the particle size distribution of the backfill soil to change the pore size distribution index, so as to maximize the capillary resistance efficiency index within the crop water suction range.

5. The method for transforming ecological terraces in arid sandy land according to claim 4, characterized in that, In S23, the calculation logic of the capillary resistance efficiency index is as follows: First, calculate the numerator, which is the product of the saturated permeability coefficient of the backfill improved soil and the power function of the effective saturation degree of the soil, where the exponent of the power function of the effective saturation degree of the soil is the pore size distribution index of the backfill improved soil; second, calculate the denominator, which is the product of the saturated permeability coefficient of the matrix sand and the power function of the effective saturation degree of the sand, where the exponent of the power function of the effective saturation degree of the sand is the pore size distribution index of the matrix sand; finally, calculate the common logarithm of the ratio of the numerator to the denominator to obtain the capillary resistance efficiency index. Among them, the pore size distribution index is obtained in advance by fitting the particle size distribution curve, and the effective saturation is calculated by substituting the matrix suction at the current interface into the moisture characteristic curve equation.

6. The method for transforming ecological terraces in arid sandy land according to claim 1, characterized in that, The method also includes steps for gravitational potential energy dissipation and steady-state control of the flow field, specifically including: S41. Based on the terrace slope and the design flood peak flow, calculate the distribution of potential energy and shear force along the flow path; S42. Construct a continuous labyrinth-type energy dissipation structure at the bottom of the water conveyance canal. The labyrinth-type energy dissipation structure includes several waterfall units arranged in a fish-scale pit pattern. S43. Based on the principle of energy density conservation and the theory of turbulent dissipation, perform dynamic calculations on the labyrinth-type energy dissipation structure to determine the energy dissipation density of a single-stage waterfall, and adjust the height and density of the single-stage waterfall unit so that the outflow velocity is lower than the critical non-scouring velocity of the soil.

7. The method for transforming ecological terraces in arid sandy land according to claim 6, characterized in that, In S43, the calculation logic for the energy dissipation density of a single-stage waterfall is as follows: multiply the fluid density, the square of the unit inflow velocity, and the comprehensive energy dissipation coefficient determined in advance through fluid dynamics simulation, and divide by two to obtain the kinetic energy dissipation term; multiply the fluid density, gravitational acceleration, single-stage waterfall height, and the preset potential energy dissipation efficiency coefficient to obtain the potential energy dissipation term. Adding the kinetic energy dissipation term to the potential energy dissipation term yields the energy dissipation density. The calculation logic for the outflow velocity is as follows: the sum of the square of the inflow velocity of the calculation unit and twice the gravitational acceleration multiplied by the height of the single-stage drop, minus twice the energy dissipation density divided by the fluid density, and the square root of the difference is taken to obtain the outflow velocity.

8. The method for transforming ecological terraces in arid sandy land according to claim 1, characterized in that, Step three specifically includes: S31. Real-time collection of moisture content, interfacial pore water pressure and slope micro-displacement of backfill improved soil layer. S32. Based on the infinite slope stability analysis method and the effective stress principle, perform a full life cycle stability assessment; S33. Calculate the permeation stress components parallel to the slope surface, and combine them with the total shear strength of the composite structure generated in step one to calculate the real-time safety factor that varies with time. The calculation logic for the real-time safety factor is as follows: Calculate the anti-sliding force term, which is the total shear strength minus the product of the interfacial pore water pressure and the tangent of the matrix internal friction angle; calculate the sliding force term, which is the product of the soil wet density, gravitational acceleration, vertical thickness of the soil layer above the sliding surface, the cosine of the terrace slope angle, and the sine of the terrace slope angle, plus the seepage stress component; divide the anti-sliding force term by the sliding force term to obtain the real-time safety factor.

9. The method for transforming ecological terraces in arid sandy land according to claim 8, characterized in that, Step three also includes evaluating the real-time safety factor to obtain the first prediction result. The specific logic includes: When the real-time safety factor is greater than 1.5, the system is determined to be in a steady state, and the stability assessment result is labeled as safe. When the real-time safety factor is greater than 1.2 and less than or equal to 1.5, the system is determined to be in an early warning state, and the stability assessment result is labeled as a risk warning. S34. Extract the irrigation control strategies corresponding to the risk warning labels. The irrigation control strategies include suspending irrigation operations on the ecological terraces in arid sandy areas.

10. A method for transforming ecological terraces in arid sandy land according to claim 9, characterized in that, Step three also includes evaluating the real-time safety factor to obtain a second prediction result. The specific logic includes: When the real-time safety factor is less than or equal to 1.2, the system is determined to be in a critical unstable state, and the stability assessment result is labeled as dangerous. S35. Extract the emergency drainage strategy corresponding to the hazard label. The emergency drainage strategy includes automatically opening the emergency overflow valve for rapid pressure relief and using the bypass channel to discharge supersaturated water to reduce the interfacial pore water pressure.

Images