Method for determining reinforcement position of stratified counter-inclined slope in reservoir area

Abstract

The invention discloses a method for determining the reinforcement position of a layered counter-inclined slope in a reservoir area. The method comprises the following steps: S1, collecting data of the layered counter-inclined slope in the reservoir area; s2, a slope model is established, simulation and damage analysis are conducted on different reinforcing positions, and the damage mode of the slope at each reinforcing position is obtained; s3, fitting relation curves between the area sizes of the damaged areas of the rock strata on the upper portion and the lower portion of the reinforced area and the reinforced positions are obtained; and S4, the two obtained fitting relation curves are drawn in the same coordinate system, and the intersection point of the two fitting relation curves serves as the optimal reinforcing position of the reservoir area layered counter-tilting slope. The numerical simulation and curve fitting technology is combined, the upper and lower rock stratum damage areas are scientifically balanced, and the method has important significance in improving the accuracy and economical efficiency of reservoir area layered counter-dip slope treatment.

Description

Technical Field

[0001] The invention relates to a method for determining a reinforcement position of a layered reverse-dip slope in a reservoir area, and belongs to the technical field of civil engineering. Background Art

[0002] Layered reverse-dip slopes in reservoir areas are a type of rock slope with unique structural characteristics and located in a unique environment. Their strata facets are oriented in the opposite direction of the slope surface and are subject to softening and erosion by reservoir water. They are common in the steep, canyon-like mountainous areas of western my country, particularly in the southwest. Previously, scholars generally believed that reverse-dip slopes were more stable than lateral slopes because they were less likely to form continuous sliding surfaces. Even if they did collapse, the depth was typically within tens of meters, generally preventing large-scale instability. Consequently, reverse-dip slopes received far less attention and recognition than lateral slopes.

[0003] Currently, prestressed anchor cables are the primary method for reinforcing layered reverse-dip slopes in reservoir areas. However, relatively little research has focused on the specific location of reinforcement. When reinforcement is positioned forward, the prestressed anchor cables are subject to the immense compressive forces from the overlying rock strata, making them susceptible to failure. Furthermore, the resulting overturned area of the overlying rock strata is large, rendering the reinforcement ineffective. When reinforcement is positioned backward, a large overturned area forms in the front of the reinforcement area, similarly rendering it ineffective. Therefore, optimal reinforcement placement is crucial for the effective reinforcement of layered reverse-dip slopes in reservoir areas. While existing research has made some progress in slope numerical simulation, strength reduction methods, and failure mode analysis, it has largely focused on evaluating the overall stability of the slope, with few systematic approaches to optimizing reinforcement placement. In particular, theoretical gaps remain regarding the coupled analysis of reservoir water dynamics and rock softening, as well as the quantitative relationship between the failure area and reinforcement location. Furthermore, traditional empirical methods struggle to adapt to complex geological conditions and engineering requirements, potentially leading to resource waste and potential engineering risks. Summary of the Invention

[0004] The purpose of the present invention is to: in response to the above-mentioned problems, provide a method for determining the reinforcement position of the layered anti-dip slope in the reservoir area, combine numerical simulation with fitting curve technology, scientifically balance the upper and lower rock strata damage areas, which is of great significance to improving the accuracy and economy of the management of the layered anti-dip slope in the reservoir area.

[0005] The technical solution adopted in the present invention is as follows:

[0006] A method for determining the reinforcement position of a layered reverse-dip slope in a reservoir area comprises the following steps:

[0007] S1. Collect data on layered reverse slopes in the reservoir area;

[0008] S2. Establish a slope model, conduct simulation and failure analysis at different reinforcement positions, and obtain the failure mode of the slope at each reinforcement position;

[0009] S3, respectively obtain the fitting relationship curves between the size of the damaged area of the upper and lower rock layers of the reinforcement area and the reinforcement position;

[0010] S4. The two obtained fitting relationship curves are plotted in the same coordinate system, and their intersection is used as the optimal reinforcement position of the layered anti-dip slope in the reservoir area.

[0011] S1 provides basic data support for subsequent modeling and analysis. If the data is inaccurate or incomplete, it may affect the accuracy of the entire model and the final selection of reinforcement positions. Therefore, this step is the basis of the entire method, and the accuracy and completeness of the data need to be ensured. S2 involves the establishment of a numerical model. By setting different reinforcement positions in the model, the failure mode of the slope under different reinforcement positions is simulated. Find out the impact of different reinforcement positions on the stability of the slope, understand which position may cause the failure of the slope, and the specific mode of failure. S3 analyzes the failure mode obtained in step S2, calculates the failure area of the upper and lower rock layers, and fits these area data with the corresponding reinforcement positions to form a mathematical relationship curve. Through this fitting, the relationship between the failure area and the reinforcement position can be quantified, providing a mathematical basis for determining the optimal position in the next step. S4 finds their intersection by superimposing the fitting curves of the upper and lower failure areas. Insufficient upper reinforcement leads to high-level collapse, while excessive reinforcement will cause low-level shear. At the intersection, the damaged areas of the upper and lower parts are equal, which means that at this reinforcement position, the damage to the upper and lower rock strata can be balanced, thereby achieving the best reinforcement effect. The optimal position is determined by mathematical methods, avoiding the subjectivity of empirical judgment. The data of S1 is the basis for subsequent modeling, the simulation results of S2 are used for the analysis of S3, and the curve of S3 is combined with S4 to find the optimal point. This solution uses numerical simulation and mathematical fitting to find the reinforcement position that can balance the damage to the upper and lower rock strata, thereby optimizing resource utilization while ensuring the reinforcement effect. The use of quantitative analysis methods instead of traditional empirical judgments improves scientificity and accuracy. The breakthrough lies in the combination of numerical simulation and mathematical fitting technology to transform complex engineering problems into mathematical optimization problems, making decisions more objective and reliable.

[0012] Alternatively, S1. Obtain the geological parameters of the layered anti-dip slope rock strata, rock physical and mechanical properties, rock strength softening coefficient, and the fluctuation pattern of the reservoir water level. The acquisition of rock stratum geological parameters breaks through the traditional homogenization assumption and can accurately characterize the unique spatial combination characteristics of the anti-dip rock strata, laying the foundation for the construction of an asymmetric failure model; the refined testing of rock physical and mechanical properties solves the problem of insufficient consideration of rock anisotropy in traditional empirical value methods and can quantify the control effect of soft rock interlayers on toppling deformation; the dynamic determination of rock strength softening coefficient incorporates the strength attenuation caused by reservoir water immersion and air drying cycles into the calculation, making up for the major defect of traditional static strength theory that cannot reflect the long-term hydrological degradation effect; the integration of monitoring data on the fluctuation pattern of reservoir water level establishes the spatiotemporal coupling relationship between the non-steady seepage field and the rock softening process, solving the problem of quantitative simulation of the toppling failure triggering mechanism caused by a sudden drop in water level causing a sudden increase in permeability. This enables the numerical model to simultaneously reflect the instability mechanism of the reverse slope in three dimensions: geological structure stabilization, material difference guidance, and hydraulic action triggering. Compared with the traditional single mechanical parameter analysis method, the degree of consistency between the model and the actual working conditions is greatly improved.

[0013] Optionally, S2 includes:

[0014] S21. Establish a numerical calculation model for layered reverse slopes in the reservoir area;

[0015] S22. calibrating the obtained geological parameters of the slope rock layer and the physical and mechanical properties of the rock to obtain initial calculation parameters of the slope rock layer and the rock layer surface;

[0016] S23. Prestressed anchor cables are used for reinforcement at different locations within the slope. The strength reduction method is used to destroy the slope rock layer, and the failure mode of the slope at each reinforcement location is obtained.

[0017] S21 breaks through the traditional continuous medium assumption and can accurately reproduce the differential deformation mechanism of soft and hard interlayered rock masses, realizing the geometric asymmetry modeling of the reverse angle between the anti-dip structural surface and the slope surface. S22's closed-loop optimization algorithm based on measured data significantly reduces human experience errors and improves the calibration accuracy of the tensile strength of the rock formation. S23, through the coordinated control of the two variables of anchor position and strength reduction, efficiently reveals the dynamic competition relationship of the failure mechanism under different reinforcement schemes, significantly improving the optimization efficiency of the engineering scheme. It reduces the overall prediction deviation of the toppling failure depth, while optimizing the uniformity of the anchor force distribution, providing a more scientific decision-making basis for deep reinforcement.

[0018] Alternatively, S21 uses discrete element software to build a slope model. This software accurately simulates the discontinuous characteristics of rock masses, breaking through the limitations of traditional continuum models. It directly captures the complex mechanical behavior of contact, separation, and rotation between rock blocks in layered, reverse-dip slopes, significantly improving the visualization and quantitative analysis capabilities of the dynamic evolution of toppling failures.

[0019] The optional initial calculation parameters of S22 include: ρ-rock density; j coh - bond strength; ten - tensile strength; j kn -normal stiffness; j fric - friction angle; R-ratio of normal stiffness to shear stiffness; a zero - initial value of fracture hydraulic width; a res - residual value of fracture hydraulic width; a max - Maximum hydraulic width of the fracture. The coordinated calibration of rock density and strength parameters accurately quantifies the dynamic balance between the self-weight stress field of the rock layer and the anti-destruction capacity of the structural surface; the joint introduction of normal stiffness, friction angle and stiffness ratio realizes the gradient description of the closure and sliding behavior of the structural surface, overcoming the shear deformation distortion problem caused by the single stiffness assumption; the dynamic evolution parameter of the hydraulic width of the fracture from the initial value to the residual value, for the first time, incorporates the positive feedback mechanism of reservoir water infiltration-fracture expansion into the calculation, and fully depicts the chain effect of hydraulic fracturing and rock mass degradation. Through the systematic integration of mechanical and hydraulic coupling variables, the model can simultaneously reflect the progressive destruction characteristics of the anti-dip slope under the interweaving action of multiple factors such as self-weight, structural surface sliding, and hydraulic erosion, significantly improving the reliability of the prediction of the toppling depth and the assessment of the anchoring demand.

[0020] Available options include:

[0021] S31: deriving the failure mode of the slope at each reinforcement position calculated in step S2, and calculating the failure area of the rock layers above and below the reinforcement area;

[0022] S32: Fitting the relationship between the area of the damaged region and the reinforcement position to obtain a fitting relationship curve.

[0023] S31 breaks through the generality of traditional overall stability evaluation by calculating the damage area of the upper and lower rock layers of the reinforcement zone separately, accurately revealing the differentiated control effects of the anchor position on toppling deformation and shear slip, and providing key quantitative indicators for subsequent dual-objective optimization. S32 transforms discrete reinforcement position and damage area data into a continuous function relationship, establishes a spatial mapping model for anchoring efficiency, breaks through the trial-and-error limitations of empirical methods, determines the optimal solution through mathematical extreme points, and achieves a leap from qualitative judgment to quantitative decision-making on reinforcement effects. It enables the selection of anchor positions to shift from being driven by subjective experience to being driven by objective data, while taking into account the dual needs of upper anti-toppling and lower anti-slip, significantly improving the scientific and economic efficiency of the reinforcement plan.

[0024] Alternatively, in S31, CAD software is used to calculate the damaged areas of the rock strata above and below the reinforcement zone. This software performs vectorized boundary extraction and area calculation on the damaged areas, overcoming the accuracy limitations of traditional manual delineation. Geometric topological analysis accurately distinguishes the complex intersecting boundaries of the upper and lower damage domains of the reinforcement zone, ensuring the objectivity and repeatability of the regional damage area statistics.

[0025] Alternatively, in S32, the ordinate is the rock failure area and the abscissa is the reinforcement location;

[0026] The relationship between the damaged area of the upper rock layer and the reinforcement position is:

[0027] A upper =-mL+m

[0028] The relationship between the damaged area of the lower rock layer and the reinforcement position is:

[0029] A lower =oL 2 +pL+q

[0030] Where A upper A is the damaged area of the upper rock layer in the reinforcement area; lower is the damaged area of the rock layer below the reinforcement area; m, n, o, p, q are all constants; L is the reinforcement position, that is, the horizontal distance from the slope toe to the center of the reinforcement area.

[0031] The linear attenuation relationship of the upper rock failure area directly reflects the inhibitory effect of the backward shift of the anchor position on the toppling deformation, and its slope parameter m quantifies the gain efficiency of the unit increase in anchor depth on the stability of the high-level rock mass. The quadratic function relationship of the lower rock failure area reveals the complex nonlinear coupling mechanism between the anchor position and shear slip failure. The upward-opening parabolic characteristic indicates that there is a critical anchor depth that minimizes the lower failure area.

[0032] The best reinforcement position in S4 is: A upper =A lower =-mL+n=oL 2 +pL+q.

[0033] The simultaneous solution of these two objectives essentially constructs a dual-objective optimization problem: controlling toppling failure and suppressing shear failure. The reinforcement location corresponding to their intersection mathematically strictly satisfies the equilibrium state of the upper and lower failure potential energies, breaking through the limitations of traditional single-objective optimization methods, which often focus on one objective while neglecting the other. This allows engineering decision-making to shift from purely numerical simulation iteration to analytical optimization, significantly improving the design efficiency and theoretical interpretability of reinforcement solutions.

[0034] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0035] 1. The present invention provides a method for determining the reinforcement location of layered reverse-dip slopes in reservoir areas. Through a technical chain of numerical simulation, failure analysis, mathematical fitting, and optimization decision-making, this method transforms complex geological engineering problems into quantifiable mathematical optimization problems. By balancing the failure zones of the upper and lower rock layers, the reinforcement location effectively suppresses the extrusion failure of the upper rock layer while controlling the toppling and instability of the lower rock layer, ultimately achieving an optimal solution for overall stability and economic efficiency.

[0036] 2. The present invention provides a method for determining the reinforcement location of layered reverse-dip slopes in a reservoir area. By using simultaneous equations, the complex geotechnical engineering problem is converted into a mathematical optimization problem that can be analytically solved. This allows the selection of reinforcement locations to have both physical mechanism clarity and computational efficiency, while providing an extensible formulaic framework for adaptive adjustment under multiple working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the overall process of the present invention;

[0038] Figure 2 are the structural parameters and strength softening coefficient of the layered reverse slope in the reservoir area of the present invention;

[0039] Figure 3 Schematic diagram of the calculation model of different reinforcement positions of layered reverse-dip slope in the reservoir area in the present invention;

[0040] Figure 4 This is a schematic diagram of determining the reinforcement position of the layered reverse-dip slope in the reservoir area in the present invention. DETAILED DESCRIPTION

[0041] The present invention will be described in detail below with reference to the accompanying drawings.

[0042] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0043] This embodiment provides a method for determining the reinforcement position of layered reverse-dip slopes in a reservoir area, such as Figure 1 As shown, the following steps are included:

[0044] S1. Taking the layered reverse-dip slope of Maocaopo No. 4 in the Wuxia section of the Three Gorges Reservoir as an example, the geological parameters of the rock strata, the physical and mechanical properties of the rock, its strength-softening coefficient, and the water level and its fluctuation pattern of the reservoir area are obtained. The strength-softening coefficients of the slope rock strata and rock layer are obtained based on indoor mechanical tests and the water level and fluctuation pattern of the Three Gorges Reservoir area.

[0045] S2:

[0046] S21. According to the results of the on-site investigation, a numerical calculation model of the layered reverse slope in the Maocaopo No. 4 reservoir area was established. Figure 2 As shown;

[0047] S22. By calibrating the obtained geological parameters of the slope rock layer and the physical and mechanical properties of the rock, initial calculation parameters of the slope rock layer and the rock layer surface are obtained, as shown in Table 1 and Table 2;

[0048] S23, use prestressed anchor cables to reinforce different locations in the slope, such as Figure 3 As shown in the figure, the strength reduction method is used to make the slope rock layer fail, and the failure mode of the slope at each reinforcement position is obtained.

[0049] Table 1 Strength parameters of the layered reverse slope rock strata in the No. 4 reservoir area of Maocaopo

[0050]

[0051] Where, ρ is rock density; j coh - bond strength; ten - tensile strength; j kn -normal stiffness; j fric - friction angle; R-ratio of normal stiffness to shear stiffness; a zero - Initial value of fracture hydraulic width; a res - residual value of fracture hydraulic width; a max - Maximum hydraulic width of the fracture.

[0052] Table 2 Strength parameters of rock layer in the layered reverse slope of the Maocaopo No. 4 reservoir area

[0053] parameter <![CDATA[T1d 2 ]]> <![CDATA[T1d 3 ]]> <![CDATA[T1d 4 、T1j 1 、T1j 2 , <![CDATA[j kn (GPa / m)]]> 14 49 14 R 0.4 0.55 0.4 <![CDATA[j coh (MPa)]]> 5.3 11.5 5.3 <![CDATA[j ten (MPa)]]> 0.9 2.3 0.9 <![CDATA[j fric (°)]]> 20 28 20 <![CDATA[a zero (m)]]> 0.003 0.003 0.003 <![CDATA[a res (m)]]> 0.001 0.001 0.001 <![CDATA[a max (m)]]> 0.015 0.015 0.015

[0054] S3. Fitting the relationship between the size of the damaged area of the upper and lower rock layers of the reinforcement area and the reinforcement position, including the following steps:

[0055] S31, importing the final failure mode of the layered reverse slope in the reservoir area calculated in step S2 into CAD software, and calculating the failure area of the upper and lower rock layers of the reinforcement area respectively using the CAD software;

[0056] S32. The obtained relationship between the size of the damaged area of the upper and lower rock layers of the reinforcement area and the reinforcement position is plotted in the same coordinate system, with the vertical axis being the rock layer damaged area and the horizontal axis being the reinforcement position, such as Figure 3 shown.

[0057] A upper =--81.511L+53560(Relationship between the upper rock layer damage area and the reinforcement position)(1)

[0058] Alower =0.1251L 2 -1.2174L-499.11 (Relationship between the damaged area of the lower rock layer and the reinforcement position) (2)

[0059] S4. The two obtained fitting curves are plotted in the same coordinate system. The intersection point is the optimal reinforcement position of the layered anti-dip slope in the reservoir area, such as Figure 4 shown.

[0060] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The present invention extends to any new features or any new combinations disclosed in this specification. Furthermore, any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the foregoing exemplary embodiments, and that any detailed technical features not disclosed in this embodiment are prior art and can be readily derived from the prior art by those skilled in the art.

Claims

1. A method for determining the reinforcement position of layered reverse-dip slopes in a reservoir area, characterized by: The following steps are involved: S1. Collect data on layered reverse slopes in the reservoir area; S2. Establish a slope model, conduct simulation and failure analysis at different reinforcement positions, and obtain the failure mode of the slope at each reinforcement position; S3, respectively obtain the fitting relationship curves between the size of the damaged area of the upper and lower rock layers of the reinforcement area and the reinforcement position; S4. The two obtained fitting relationship curves are plotted in the same coordinate system, and their intersection is used as the optimal reinforcement position of the layered anti-dip slope in the reservoir area.

2. The method for determining the reinforcement position of a layered reverse-dip slope in a reservoir area according to claim 1, wherein: S1. Obtain the geological parameters of the layered reverse slope rock strata in the reservoir area, the physical and mechanical properties of the rock, the rock strength softening coefficient, and the rising and falling patterns of the reservoir water level.

3. The method for determining the reinforcement position of a layered reverse-dip slope in a reservoir area according to claim 1, characterized in that: S2 includes: S21. Establish a numerical calculation model for layered reverse slopes in the reservoir area; S22. calibrating the obtained geological parameters of the slope rock layer and the physical and mechanical properties of the rock to obtain initial calculation parameters of the slope rock layer and the rock layer surface; S23. Prestressed anchor cables are used for reinforcement at different locations within the slope. The strength reduction method is used to destroy the slope rock layer, and the failure mode of the slope at each reinforcement location is obtained.

4. The method for determining the reinforcement position of a layered reverse-dip slope in a reservoir area according to claim 3, characterized in that: S21 uses discrete element software to establish a slope model.

5. The method for determining the reinforcement position of a layered reverse-dip slope in a reservoir area according to claim 3, characterized in that: The initial calculation parameters of S22 include: ρ-rock density; j coh - bond strength; ten - tensile strength; j kn -normal stiffness; j fric - friction angle; R-ratio of normal stiffness to shear stiffness; a zero - initial value of fracture hydraulic width; a res - residual value of fracture hydraulic width; a max - Maximum hydraulic width of the fracture.

6. The method for determining the reinforcement position of a layered reverse-dip slope in a reservoir area according to claim 1, characterized in that: S3 includes: S31: deriving the failure mode of the slope at each reinforcement position calculated in step S2, and calculating the failure area of the rock layers above and below the reinforcement area; S32: Fitting the relationship between the damaged area and the reinforcement position to obtain a fitting relationship curve.

7. The method for determining the reinforcement position of a layered reverse-dip slope in a reservoir area according to claim 6, characterized in that: In S31, the CAD software is used to calculate the damaged area of the rock layers above and below the reinforcement area.

8. The method for determining the reinforcement position of a layered reverse-dip slope in a reservoir area according to claim 6, characterized in that: In S32, the vertical axis is the rock layer damage area, and the horizontal axis is the reinforcement position. The relationship between the upper rock layer damage area and the reinforcement position is: THE upper =-mL+n The relationship between the damaged area of the lower rock layer and the reinforcement position is: A lower =oL 2 +pL+q Where A upper A is the damaged area of the upper rock layer in the reinforcement area; lower is the damaged area of the rock layer below the reinforcement area; m, n, o, p, q are all constants; L is the reinforcement position, that is, the horizontal distance from the slope toe to the center of the reinforcement area.

9. The method for determining the reinforcement position of a layered reverse-dip slope in a reservoir area according to claim 8, characterized in that: In S4, the best reinforcement position is: A upper =A lower =-mL+n=oL 2 +pL+q.

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