Method for analyzing stability of unsaturated sandy-soil-shaped two-long granite slope

Abstract

The invention provides an unsaturated sandy soil-shaped two-long granite slope stability analysis method, and relates to the technical field of unsaturated soil mechanics and engineering geology, and the method comprises the following steps: correcting a BC water retention function model through a first correction parameter, and constructing to obtain an unsaturated sandy soil water retention function model; correcting the BC permeability coefficient model according to the second correction parameter, and constructing to obtain an unsaturated sand permeability coefficient model; and analyzing the stability of the two-long granite slope by combining the unsaturated sand water holding function model and the unsaturated sand permeability coefficient model to obtain a stability analysis result. According to the method, the traditional BC water holding function and permeability coefficient model is improved by using the first correction parameter and the second correction parameter, and the residual value is used for replacing a film flow parameter which is difficult to predict in the previous model, so that the suction range is expanded, and the unsaturated slope formation mechanism is analyzed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of unsaturated soil mechanics and engineering geology, and is applied to the stability analysis of unsaturated sandy monzonitic granite slope under rainfall conditions. BACKGROUND

[0002] Compared with traditional ground oil tanks, underground storage has the advantages of high safety factor, small land occupation, less resource consumption, less pollution, less investment, long service life, low operation and management cost, and fast loading and unloading, and is more and more widely used. At present, the construction of oil storage in China is in a very important development period. Underground water-sealed oil storage has a series of characteristics such as high side wall, large span, no lining, long-term coupling of multi-phase medium, long-term disturbance of multiple factors, no maintenance conditions, etc., which determines that the underground water-sealed oil storage is different from the general underground engineering. The stability analysis of the slope at the entrance of the underground water-sealed oil storage, as the first step of the construction of the water-sealed storage, plays a crucial role. At present, in actual engineering, only the stability analysis under natural and rainstorm conditions is carried out, and the stability analysis of the unsaturated sandy monzonitic granite slope under unsaturated conditions is rarely carried out.

[0003] The influence of rainfall on slope stability has been paid special attention by domestic and foreign experts. Guzzetti obtained the rainfall threshold value inducing slope through processing massive slope data; Floris established a modified critical rainfall slope model. Crozier proposed a formula for calculating the effective rainfall in the early stage. Domestic scholars have also made many achievements in studying the influence of rainfall on slope stability. For example, Wu Shuren et al. completed the slope early warning research of the Three Gorges Reservoir through statistical analysis of the slope disaster data of the Three Gorges Reservoir in recent years, and through the slope state early warning and slope time and space prediction criterion; Wu Gang et al. found the action process of groundwater on the slope after rainfall infiltration through the stage-by-stage study of the Wulipo slope in Dujiangyan.

[0004] In the prior art, although the VG (van Genuchten) model can predict the relationship between the water content and the matrix suction in the high suction stage, and can better simulate the SWCC (soil-water characteristic curve) of fine-grained soil. However, since the strongly weathered granite with large particle size starts to discharge pore water when the suction changes little, the prediction result of the VG model is not intuitive. The BC model is proposed by Brooks-Corey in 1964, and is more suitable for coarse-grained soil. Such soil can discharge pore water when the suction changes little, and the calculation effect is poor for sandy monzonitic granite.

[0005] In view of the problems in the prior art, the present invention provides a method for analyzing the stability of unsaturated sandy monzonitic granite slopes. Summary of the Invention

[0006] In order to better fit the actual situation of unsaturated sandy monzonitic granite slopes, the slope stability of unsaturated sandy monzonitic granite under rainfall conditions is analyzed. The present invention provides a method for analyzing the stability of unsaturated sandy monzonitic granite slopes, which method comprises:

[0007] The BC water retention function model is modified by the first correction parameter to construct the unsaturated sand water retention function model;

[0008] The BC permeability coefficient model is modified according to the second correction parameter to construct the unsaturated sand permeability coefficient model;

[0009] The stability of the monzonitic granite slope is analyzed by combining the unsaturated sand water retention function model and the unsaturated sand permeability coefficient model to obtain a stability analysis result.

[0010] According to one embodiment of the present invention, the BC water holding function model is:

[0011]

[0012] Where: S e is saturation; b is the inlet pressure value; ψ is the matrix suction; λ is the pore size distribution index;

[0013] The first correction parameter is:

[0014]

[0015] Where: C(ψ) is the first correction parameter; c is the proportional factor; ψ a is the matrix suction corresponding to the completely dry point; ψ c are fitting parameters related to the residual values.

[0016] According to one embodiment of the present invention, the unsaturated sand water retention function model is:

[0017]

[0018] Where: S e is the saturation; C(ψ) is the first correction parameter; ψ b is the inlet pressure value; ψ is the matrix suction; λ is the pore size distribution index.

[0019] According to one embodiment of the present invention, the BC permeability coefficient model is:

[0020]

[0021] wherein: k(ψ) is the permeability coefficient; k s is the saturated permeability coefficient; ψ b is the air entry pressure value; ψ is the matric suction; η = 2 + 3λ; λ is the pore size distribution index;

[0022] The second correction parameter is:

[0023]

[0024] wherein: Γ(ψ) is the second correction parameter; ψ r is the residual value; s, t are fitting parameters.

[0025] According to an embodiment of the present application, the unsaturated sandy soil permeability coefficient model is:

[0026]

[0027] wherein: k(ψ) is the permeability coefficient; k s is the saturated permeability coefficient; Γ(ψ) is the second correction parameter; ψ b is the air entry pressure value; ψ is the matric suction; η = 2 + 3λ; λ is the pore size distribution index.

[0028] According to an embodiment of the present application, the residual value is a matric suction value corresponding to an intersection point of a first tangent line of an inflection point on a capillary stage of a water retention curve and a second tangent line passing through a completely dry point, wherein the inflection point coordinates are (ψ i , S i ), the first tangent line is l1, the completely dry point coordinates are (a, 0), and the second tangent line is l2.

[0029] According to an embodiment of the present application, the residual value is solved by the following steps:

[0030] Deriving the unsaturated sandy soil water retention function model to obtain a first derivative water retention function model;

[0031] In the capillary stage of the water retention curve, the first correction coefficient is equal to one, and the first derivative water retention function model is simplified to obtain a first derivative capillary stage model;

[0032] Deriving the first derivative capillary stage model to obtain a second derivative capillary stage model;

[0033] Solving the inflection point coordinates by simultaneously solving the second derivative capillary stage model and the unsaturated sandy soil water retention function model;

[0034] In the adsorption stage of the water retention curve, the volume moisture content is constant, so the first derivative water retention function model is simplified to obtain a first derivative adsorption stage model;

[0035] The first tangent equation is obtained in combination with the inflection point coordinates and the first derivative capillary stage model;

[0036] The second tangent equation is obtained in combination with the complete drying point coordinates and the first derivative adsorption stage model;

[0037] The residual value is obtained by simultaneously solving the first tangent equation and the second tangent equation.

[0038] According to one embodiment of the present application, the stability analysis result is obtained by the following steps:

[0039] Based on the unsaturated sand water retention function model and the unsaturated sand permeability coefficient model, the rainfall simulation result is obtained by simulating the rainfall condition through numerical simulation;

[0040] According to the rainfall simulation result, the deformation analysis result of the monzogranite slope is obtained by using the coupled stress / pore water pressure;

[0041] According to the rainfall simulation result, the stability coefficient result of the monzogranite slope is obtained by using the limit equilibrium method;

[0042] According to the rainfall simulation result, the pore water pressure distribution analysis result of the monzogranite slope under natural and rainfall conditions is obtained, and the pore pressure redistribution result is obtained;

[0043] The deformation analysis result, the stability coefficient result and the pore pressure redistribution result are taken as the stability analysis result.

[0044] According to another aspect of the present application, a storage medium containing a series of instructions for executing the method steps as described above is also provided.

[0045] According to another aspect of the present application, an unsaturated sand monzogranite slope stability analysis device is also provided, which executes any one of the methods described above, and the device comprises:

[0046] The water retention function module modifies the BC water retention function model by a first correction parameter to construct an unsaturated sand water retention function model;

[0047] The permeability coefficient module modifies the BC permeability coefficient model according to a second correction parameter to construct an unsaturated sand permeability coefficient model;

[0048] The stability analysis module combines the unsaturated sand soil water retention function model and the unsaturated sand soil permeability coefficient model to analyze the stability of the monzonite granite slope, and obtains a stability analysis result.

[0049] The application provides a monzonite granite slope stability analysis method for unsaturated sand soil, which has the following advantages compared with the prior art.

[0050] 1) In order to better adapt to the actual situation of the unsaturated sand soil monzonite granite slope of the underground water sealing cave, the application provides a monzonite granite slope stability analysis method for unsaturated sand soil, which improves the traditional BC water retention function and permeability coefficient model by using a first correction parameter and a second correction parameter, replaces the thin film flow parameter which is difficult to predict in the previous model by a residual value, and expands the suction range, so as to analyze the formation mechanism of the unsaturated slope.

[0051] 2) The modified unsaturated sand soil water retention function model is approximately linear in the large adsorption stage, and can better adapt to the actual situation of the unsaturated sand soil monzonite granite slope.

[0052] 3) In practical application, the modified unsaturated sand soil water retention function model can be combined with the GeoStudio software. The SLOPE / W, SEEP / W and SIGMA / W modules in the GeoStudio are coupled to realize rainfall simulation calculation by numerical simulation, so as to realize the analysis of the stability coefficient, stress and deformation of the unsaturated sand soil monzonite granite slope under rainfall.

[0053] Other features and advantages of the application will be set forth in the specification, and in part will become apparent from the specification, or can be learned by practice of the application. The objectives and other advantages of the application can be realized and attained by the structure particularly pointed out in the specification, claims and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0054] The accompanying drawings are included to provide a further understanding of the application, and constitute a part of the specification, which together with the application, serve to explain the application, and do not constitute a limitation of the application. In the drawings:

[0055] Figure 1 A step flow chart of a monzonite granite slope stability analysis method for unsaturated sand soil according to one embodiment of the application is shown;

[0056] Figure 2 A water retention curve diagram corresponding to the traditional BC water retention function model is shown;

[0057] Figure 3 A curve diagram corresponding to the first correction parameter when the scale factor takes different values according to one embodiment of the application is shown.

[0058] Figure 4 A water retention curve diagram corresponding to a non-saturated sand soil water retention function model according to an embodiment of the present application is shown;

[0059] Figure 5 A SEEP / W pore water pressure analysis diagram according to an embodiment of the present application is shown;

[0060] Figure 6 A SIGMA / W coupled stress / pore water pressure displacement analysis diagram according to an embodiment of the present application is shown;

[0061] Figure 7 A SLOPE / W stability factor calculation diagram according to an embodiment of the present application is shown;

[0062] Figure 8 A natural state stress analysis diagram according to an embodiment of the present application is shown;

[0063] Figure 9 A rainfall condition stress analysis diagram according to an embodiment of the present application is shown;

[0064] Figure 10 A slope toe deformation curve diagram according to an embodiment of the present application is shown;

[0065] Figure 11 A natural state slope stability diagram according to an embodiment of the present application is shown;

[0066] Figure 12 A rainfall condition slope stability diagram according to an embodiment of the present application is shown;

[0067] Figure 13 A pore water pressure distribution diagram under a natural state according to an embodiment of the present application is shown;

[0068] Figure 14 A pore water pressure distribution diagram under a 0.3m rainfall according to an embodiment of the present application is shown.

[0069] In the drawings, the same components are designated by the same reference numerals. In addition, the drawings are not drawn to scale. DETAILED DESCRIPTION

[0070] In order to make the objects, technical solutions, and advantages of the present application clearer, the following further describes embodiments of the present application with reference to the drawings.

[0071] The influence of rainfall on slope stability has been paid special attention by experts at home and abroad. Guzzetti(Guzzetti P. Peruccacci S. Rossi M. et al. Rainfall thesholds for the initiation of landslides in central and southern Europe[J]. Meteorol Aroms Phys., 2007, 12(98): 239-297.)(Guzzetti P. Peruccacci S. Rossi M. et al. The rainfall intensity-duration control of shallow landslides and debris flow[J]. Landslides. 2008, 7(3): 3-17.) obtained the rainfall threshold value of slope by processing a large amount of slope data; Floris(Floris B. Evaluation of landslides reactivation: A modified rainfall threshold model based on historical racords of rainfall and landslides[J]. Geomorphology, 2008, 18(9): 40-57.) established a modified rainfall threshold model for slope. Crozier(Crozier MJ. Eyles RJ. Assessing the problbility of rapid mass movement[C]The New Zealand Institution of Engineers. Proceeding of Technical Groups. Proc. Third Australian-New Zealand Conference on Geomechanics. Wellington: [s.n.], 1984: 247-251) proposed the formula for calculating the effective rainfall before the slope failure.Many domestic scholars have made many achievements in the study of the influence of rainfall on the stability of slopes. For example, Wu Shuren (Wu Shuren, Jin Yimin, Shi Jusong, Zhang Yongshuang, Han Jinliang, He Feng, Dong Cheng. Preliminary study on landslide early warning criteria: Taking the Three Gorges Reservoir Area as an example [J]. Journal of Jilin University (Earth Science Edition), 2004(04): 596-600. DOI:10.13278 / j.cnki.jjuese.2004.04.020.) and others analyzed the slope disaster data of the Three Gorges Reservoir in recent years, and completed the slope early warning research of the Three Gorges Reservoir through slope state early warning and slope time and space prediction criteria; Wu Gang (Wu Gang. Research on the formation and evolution mechanism of the Wulipo landslide in Dujiangyan [D]. Chengdu University of Technology, 2016.) and others studied the Wulipo slope of Dujiangyan in stages and found the role of groundwater in the slope after rainfall infiltration.

[0072] The curve representing the relationship between the change of suction and the change of water content in unsaturated soil is called the water retention curve (WRC or SWRC) or the soil-water characteristic curve (SWCC). The water retention curve can be used to predict the hydraulic-mechanical properties of unsaturated soil, such as permeability, strength, and volume change, and is an important tool for studying the properties of unsaturated soil. Many scholars have proposed numerous different types of unsaturated soil water retention curve models, including: ① empirical or semi-empirical water retention curve models based on curve shape or statistical analysis, such as the classic BC model, VG model, and FX model; ② water retention curve models considering particle size gradation or pore structure characteristics; ③ water retention curve models considering soil deformation; ④ water retention curve models based on thermodynamics, fractals, or surface science; and ⑤ water retention curve models considering adsorption and capillary water retention mechanisms. These models can all well describe the water retention curve under specific conditions and play an important role in the study of unsaturated soil coupling constitutive models.

[0073] In the prior art, the VG model can predict the relationship between water content and matrix suction at high suction, and can better simulate the SWCC of fine-grained soil. However, since the strongly weathered granite with large particle size starts to drain pore water when the suction changes little, the prediction result using the VG model is not intuitive. The BC model was proposed by Brooks-Corey in 1964 and is more suitable for coarse-grained soil. This type of soil can drain pore water when the suction changes little, and the calculation result is poor for sandy-like monzonitic granite.

[0074] In order to better fit the actual situation of the unsaturated sandy soil-like monzonitic granite slope, the application modifies the BC water retention function model by combining the first correction parameter C(ψ) on the basis of the traditional BC model, and obtains the modified unsaturated sandy soil water retention function model; the second correction coefficient Γ(ψ) is introduced, and the residual value is determined by using the water retention curve, so that the film flow parameter which is difficult to predict in the previous model is replaced. It is found through comparison that the modified unsaturated sandy soil water retention function model is approximately linear at a higher suction stage, and can better reflect the relationship between the water content and the matrix suction in the unsaturated sandy soil-like monzonitic granite.

[0075] Figure 1 A step flow chart of an unsaturated sandy soil-like monzonitic granite slope stability analysis method according to an embodiment of the application is shown.

[0076] As Figure 1 shown, in step S1, the BC water retention function model is modified by the first correction parameter, and the unsaturated sandy soil water retention function model is constructed.

[0077] In practice, the equation proposed by Brooks and Corey is one of the earliest methods to simulate the soil-water characteristic curve. On the basis of a large number of washing and moisture content test data, Brooks and Corey proposed a two-part power function expression (BC water retention function model) related to the "pore size distribution index" λ of soil. According to the air pressure value ψ b , the mathematical model presents a non-smooth or open form. In an embodiment, the traditional BC water retention function model is:

[0078]

[0079] Wherein: S e is the saturation; ψ b is the air pressure value; ψ is the matrix suction; and λ is the pore size distribution index.

[0080] As Figure 2 known: the water retention function with a relatively large λ value indicates that the soil body drains quickly and is more sensitive to suction changes.

[0081] In order to describe the water retention curve at the high matrix suction stage, Fredlund et al. (1994) introduced the correction parameter C(ψ) and established the FX water retention function model, which extended the description of the water retention curve at the capillary stage to the adsorption stage. For the FX water retention function model, Wang et al. (2016) added a proportional factor c to C(ψ) to improve the FX model and describe the double-drop water retention curve. The improved C(ψ) expression is as formula (2):

[0082]

[0083] wherein: C(ψ) is a first correction parameter; c is a proportional factor; ψ a is a matrix suction corresponding to a completely dry point; ψ c is a fitting parameter related to a residual value.

[0084] In the prior art and practice, the correction coefficient C(ψ) shown in formula (2) is used to improve the FX model, but through a large number of practical researches, the inventors of the present application find that when the first correction coefficient C(ψ) is used to correct the traditional BC water retention function model, it can linearly decrease in the residual region (a larger adsorption stage), so as to meet the actual law and be more in line with the actual situation of the research object (unsaturated sand-like monzonitic granite slope) of the present application.

[0085] Specifically, Figure 3 The parameter ψ c is drawn, and a curve of the first correction parameter C(ψ) when the proportional factor c takes different values, the curve has a characteristic value, that is, ψ c / c. When the matrix suction is less than the characteristic value, the value of C(ψ) is close to 1; when the matrix suction is greater than the characteristic value, C(ψ) linearly decreases to 0. The present application uses the characteristics of the first correction parameter C(ψ) to correct the traditional BC water retention function model, so that it can linearly decrease in the residual region (a larger adsorption stage), thereby meeting the actual law.

[0086] The present application substitutes the first correction parameter C(ψ) into formula (1), so that the traditional BC model is extended to a larger suction stage, and then the expression of the corrected unsaturated sand water retention function model is as formula (3).

[0087] In one embodiment, the unsaturated sand water retention function model is:

[0088]

[0089] wherein: S e is a saturation; C(ψ) is a first correction parameter; ψ b is an air entry pressure value; ψ is a matrix suction; and λ is a pore size distribution index.

[0090] The water retention curve of the corrected unsaturated sand water retention function model provided by the present application is as shown in Figure 4 . It can be known from Figure 4 that the corrected water retention curve is in an approximate linear relationship in the residual region (a larger adsorption stage), which indicates that compared with the traditional BC model, the unsaturated sand water retention function model provided by the present application can better reflect the relationship between the water content of a sand layer with good permeability and the matrix suction.

[0091] In summary, the present invention creatively uses the first correction parameter C(ψ), which was originally used to correct the FX model, to correct the traditional BC model. The unsaturated sand water retention function model obtained after correction is exactly consistent with the actual situation of the research object of the present invention (unsaturated sandy monzonitic granite slope).

[0092] like Figure 1 As shown, in step S2, the BC permeability coefficient model is corrected according to the second correction parameter to construct an unsaturated sand permeability coefficient model.

[0093] In one embodiment, the traditional BC permeability coefficient model is:

[0094]

[0095] Where: k(ψ) is the permeability coefficient; k s is the saturated permeability coefficient; ψ b is the inlet pressure value; ψ is the matrix suction; η=2+3λ; λ is the pore size distribution index.

[0096] The present invention introduces a second correction parameter Γ(ψ) to correct the traditional BC permeability coefficient model, where:

[0097]

[0098] Among them: K r 、k r are the first and second unsaturated permeability coefficients.

[0099] In one embodiment, the second correction parameter is:

[0100]

[0101] Where: Γ(ψ) is the second correction parameter; ψ r is the residual value; s and t are fitting parameters that control the slope of the permeability curve in the residual zone.

[0102] In one embodiment, the unsaturated sand permeability coefficient model is:

[0103]

[0104] Where: k(ψ) is the permeability coefficient; k s is the saturated permeability coefficient; Γ(ψ) is the second correction parameter; ψ b is the inlet pressure value; ψ is the matrix suction; η=2+3λ; λ is the pore size distribution index.

[0105] In the prior art and practice, the correction coefficient Γ(ψ) shown in formula (6) was used to improve the VG model. However, after extensive practical research, the inventors of the present invention found that when the second correction coefficient Γ(ψ) was used to modify the traditional BC permeability coefficient model using the thin film flow mechanism, it was possible to distinguish between the capillary (water) stage and the adsorption (water) stage, thereby satisfying the actual law and being more in line with the actual situation of the research object of the present invention (unsaturated sandy monzonitic granite slope).

[0106] In summary, the present invention creatively uses the second correction parameter Γ(ψ), which was originally used to correct the VG model, to correct the traditional BC model. The unsaturated sand permeability coefficient model obtained after correction can just meet the actual situation of the research object of the present invention (unsaturated sandy monzonitic granite slope).

[0107] In one embodiment, the residual value ψ r is the matrix suction value corresponding to the intersection of the first tangent line passing through the capillary stage inflection point on the water retention curve and the second tangent line passing through the completely dry point, where the inflection point coordinates are (ψ i , S i ), the first tangent is l1, the coordinates of the completely dry point are (a, 0), and the second tangent is l2. Specifically, a is a constant whose value depends on the properties of the research object (e.g., unsaturated sand). In one embodiment, a is 20.

[0108] In one embodiment, the residual value is solved through steps S21 - S28 .

[0109] In step S21, the unsaturated sand water retention function model is differentiated to obtain a first-order derivative water retention function model.

[0110] Specifically, in order to obtain the residual value coordinates, the unsaturated sand water retention function model must be differentiated first. The first-order derivative water retention function model is shown in formula (8):

[0111]

[0112] In step S22 , in the capillary stage of the water retention curve, the first correction coefficient is equal to one, and the first-order conductance water retention function model is simplified to obtain a first-order conductance capillary stage model.

[0113] Specifically, when ψ<ψ r When , the unsaturated sand water retention function model degenerates into the traditional BC water retention function model, that is, C(ψ) is 1, then Equation (8) is simplified to the first-order derivative capillary stage model shown in Equation (9):

[0114]

[0115] In step S23, the first derivative capillary stage model is differentiated to obtain a second derivative capillary stage model.

[0116] Specifically, the second derivative of the water retention curve at the inflection point (ψ i , S i ) of the capillary stage is 0, and the second derivative capillary stage model is:

[0117]

[0118] In step S24, the second derivative capillary stage model and the unsaturated sand permeability coefficient model are solved to obtain the inflection point coordinates. Specifically, the simultaneous equations (10) and (3) can obtain the inflection point coordinates (ψ i , S i ).

[0119] In step S25, in the adsorption stage of the water retention curve, the volumetric water content is constant, and the first derivative water retention function model is simplified to obtain a first derivative adsorption stage model.

[0120] Specifically, when entering the adsorption water stage, the soil is in a residual saturated state, and the volumetric water content is constant, i.e., S' = 0, and the first derivative adsorption stage model is:

[0121]

[0122] In step S26, the first tangent equation is obtained in combination with the inflection point coordinates and the first derivative capillary stage model.

[0123] In step S27, the second tangent equation is obtained in combination with the complete dry point coordinates and the first derivative adsorption stage model.

[0124] Specifically, l1 is tangent to the water retention curve of the unsaturated sand water retention function model at the point (ψ i , S i ), and l2 is tangent to the water retention curve of the unsaturated sand water retention function model at the point (a, 0), so the derivative of the water retention curve of the unsaturated sand water retention function model at (ψ i , S i ) and (a, 0) is the slope of the straight line, and thus the straight line equations of l1 and l2 are formula (12) and formula (13) respectively:

[0125]

[0126]

[0127] In step S28, the residual value is obtained by simultaneously solving the first tangent equation and the second tangent equation. Specifically, the residual value ψ r.

[0128] The present invention introduces the first correction parameter C(ψ) and the second correction parameter Γ(ψ) to obtain the unsaturated sand water retention function model and the unsaturated sand permeability coefficient model, and the residual value ψ r The method replaces the thin film flow parameters that are difficult to predict in previous models. It not only conforms to the actual situation of the research object of the present invention (unsaturated sandy monzonitic granite slope), but also has a simple calculation process and high convenience.

[0129] like Figure 1 As shown, in step S3, the stability of the monzonitic granite slope is analyzed by combining the unsaturated sand water retention function model and the unsaturated sand permeability coefficient model to obtain the stability analysis result.

[0130] In one embodiment, stability analysis results are obtained through steps S31 - S35 .

[0131] In step S31, based on the unsaturated sand water retention function model and the unsaturated sand permeability coefficient model, a rainfall condition is simulated by numerical simulation to obtain a rainfall simulation result.

[0132] Specifically, it is assumed that the monzonitic granite slope is in a stable state for a long time before the rainy season. In order to completely restore the occurrence environment of the monzonitic granite slope, it is assumed that the slope is in an unsaturated state at the initial stage of rainfall. The unsaturated sand water retention function model is input into the numerical simulation software (such as GeoStudio software), combined with the unsaturated sand permeability coefficient model, and the permeability coefficient is calculated according to the above formula. The SLOPE / W, SEEP / W and SIGMA / W modules in GeoStudio are used for rainfall simulation calculations. Among them, the SLOPE / W module performs stability analysis based on the limit equilibrium method; the SIGMA / W module performs stress-strain analysis based on finite elements; and SEEP / W can perform pore water pressure, total water head, and pressure head redistribution calculations. The three can be coupled with each other to realize the calculation of the slope stability coefficient, stress, and deformation distribution caused by rainfall. The model establishment is as follows Figure 5-7 .

[0133] In step S32, based on the rainfall simulation results, coupled stress / pore water pressure is used to perform deformation analysis on the monzonitic granite slope to obtain deformation analysis results.

[0134] Specifically, in step S32, slope deformation analysis is performed under rainfall conditions. After the SEEP / W simulation is completed, slope deformation after rainfall is analyzed and calculated. First, the rainfall simulation results are imported into the SIGMA / W module, and slope deformation analysis is performed using coupled stress / pore water pressure. The analysis results are as follows: Figure 8-10 .

[0135] In step S33, according to the rainfall simulation result, the limit equilibrium method is used to analyze the stability of the monzonite granite slope, and the stability coefficient result is obtained.

[0136] Specifically, in step S33, the slope stability coefficient under the rainfall condition is calculated, the rainfall simulation result is introduced into the SLOPE / W module to calculate the slope stability coefficient, and the analysis result is as shown in Figure 11-12 .

[0137] As shown in Figure 11-12 , according to the SLOPE / W calculation result, the rainfall will reduce the stability coefficient of the unsaturated sandy monzonite granite slope. The reason is that for the unsaturated sandy monzonite granite slope, within a certain range of volume water content, the matric suction has an increasing effect on the strength of the soil, the size of the effect has a certain functional relationship with the water content, and there is a critical value of water content. When the water content is less than the critical value, the increasing effect on the strength gradually decreases with the increase of the water content. When the critical value is exceeded, the increase of the water content will reduce the slope stability coefficient. Therefore, in the slope treatment design, the slope support strength should be fully considered, and the influence of matric suction on the slope stability should be avoided as much as possible.

[0138] In step S34, according to the rainfall simulation result, the pore water pressure distribution of the monzonite granite slope under natural and rainfall conditions is analyzed, and the pore pressure redistribution result is obtained.

[0139] Specifically, in step S34, the pore pressure redistribution of the unsaturated slope is carried out, and the SEEP / W is used to analyze the pore water pressure distribution under natural and rainfall conditions. The soil-water characteristic curve is input through the SEEP / W unsaturated material, and the unsaturated state permeability coefficient is calculated through formula (5). The pore pressure distribution is as shown in Figure 13 , Figure 14 .

[0140] In step S35, the deformation amount analysis result, the stability coefficient result and the pore pressure redistribution result are taken as the stability analysis result.

[0141] In summary, through step S3, the author analyzes the mechanism of the apparent cohesion on the unsaturated sandy monzonite granite slope: for the unsaturated sandy monzonite granite slope, within a certain range of volume water content, the matric suction has an increasing effect on the strength of the soil, the size of the effect has a certain functional relationship with the water content, and there is a critical value of water content. When the water content is less than the critical value, the increasing effect on the strength gradually decreases with the increase of the water content. When the critical value is exceeded, the increase of the water content will reduce the slope stability coefficient. Therefore, in the slope treatment design, the slope support strength should be fully considered, and the influence of matric suction on the slope stability should be avoided as much as possible.

[0142] The application firstly adopts the modified parameters C(ψ) and Γ(ψ) to optimize the traditional BC water retention function and the permeability coefficient model, expands the suction range, and analyzes the stability of the unsaturated sand-like monzonitic granite slope under the rainfall condition, which conforms to the actual situation of the research object (the unsaturated sand-like monzonitic granite slope).

[0143] The application provides a kind of unsaturated sand-like monzonitic granite slope stability analysis method, which can also be combined with a computer readable storage medium, and the computer program is stored on the storage medium, and a computer program is executed to run a kind of unsaturated sand-like monzonitic granite slope stability analysis method.

[0144] The computer readable storage medium can include any entity or device that can carry computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium.

[0145] It should be noted that the content contained in the computer readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction, for example, in some jurisdictions, according to legislation and patent practice, the computer readable storage medium does not include electrical carrier signals and telecommunication signals.

[0146] According to another aspect of the application, an unsaturated sand-like monzonitic granite slope stability analysis device is also provided, which executes an unsaturated sand-like monzonitic granite slope stability analysis method, and the device comprises a water retention function module, a permeability coefficient module and a stability analysis module.

[0147] In one embodiment, the water retention function module modifies the BC water retention function model by a first modified parameter to construct an unsaturated sand water retention function model; the permeability coefficient module modifies the BC permeability coefficient model according to a second modified parameter to construct an unsaturated sand permeability coefficient model; and the stability analysis module analyzes the stability of the monzonitic granite slope in combination with the unsaturated sand water retention function model and the unsaturated sand permeability coefficient model to obtain a stability analysis result.

[0148] In summary, the application provides an unsaturated sand-like monzonitic granite slope stability analysis method, which has the following advantages compared with the prior art.

[0149] 1) In order to better fit the actual situation of the unsaturated sandy soil-like monzonitic granite slope of the underground water-sealed cave mouth slope, the application provides an unsaturated sandy soil-like monzonitic granite slope stability analysis method, a first correction parameter and a second correction parameter are used to improve a traditional BC water holding function and a permeability coefficient model, a residual value is used to replace a film flow parameter which is difficult to predict in a previous model, and a range of suction is expanded, so that the formation mechanism of the unsaturated slope is analyzed.

[0150] 2) The corrected unsaturated sandy soil water holding function model is approximately linear in a large adsorption stage, and can better fit the actual situation of the unsaturated sandy soil-like monzonitic granite slope.

[0151] 3) In actual application, the corrected unsaturated sandy soil water holding function model can be combined with the GeoStudio software. The SLOPE / W, SEEP / W and SIGMA / W modules in the GeoStudio are used to perform rainfall simulation calculation through numerical simulation, the three modules are coupled, and the stability coefficient, stress and deformation of the unsaturated sandy soil-like monzonitic granite slope under rainfall are analyzed.

[0152] It should be understood that the embodiments disclosed in the present application are not limited to the specific structure, processing steps or materials disclosed herein, but should extend to equivalent alternatives of these features understood by those skilled in the relevant art. It should also be understood that the terms used herein are for the purpose of describing specific embodiments only and are not meant to be limiting.

[0153] In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more; the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", "front end", "rear end", "head", "tail" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" and the like are only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0154] In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0155] Certain terminology is used in this application file to refer to particular system components. As will be appreciated by one skilled in the art, the same component can be referred to by different names, and so the application file does not intend to distinguish between components that differ in name but not in function. In this application file, the terms "comprise," "include" and "have" are used in an open-ended fashion, and thus should be interpreted to mean "including, but not limited to...." Also, the term "substantially" or "essentially" or "approximately" as can be employed in the specification and claims of this application file, refers to industry-accepted tolerances for the respective term. The term "coupled" as can be employed in the specification and claims of this application file, encompasses both direct coupling and indirect coupling via another component, element, circuit, or module where, for indirect coupling, the intermediary component, element, circuit, or module does not alter the information of a signal but can adjust its current level, voltage level, and / or power level. Coupling by way of an intermediary component, element, circuit, or module (e.g., where one element is coupled to another element by way of an intermediary component, element, circuit, or module) includes both direct and indirect coupling between the two elements in the same manner as "coupled."

[0156] As used in the specification and claims, the phrase "one embodiment," or "an embodiment," means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the application. The appearances of the phrase "in one embodiment" or "an embodiment" in various places in the specification are not necessarily all referring to the same embodiment.

[0157] Embodiments of the application are presented by way of example and not limitation. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments were chosen and described in order to best explain the principles of the application and its practical application, and to enable others skilled in the art to understand the application for various embodiments with various modifications as are suited to the particular use contemplated.

[0158] Although the present disclosure has been disclosed by way of the embodiments described above, the above description is not exhaustive and does not limit the present disclosure to the disclosed embodiments. Any modifications and variations of the disclosed embodiments that are apparent to those of ordinary skill in the art are intended to be within the scope of the present disclosure. The scope of the patent protection is defined by the appended claims.

Claims

1. A method for analyzing the stability of unsaturated sandy monzonitic granite slopes, characterized in that: The method comprises: The BC water retention function model is modified by the first correction parameter to construct the unsaturated sand water retention function model; The BC permeability coefficient model is modified according to the second correction parameter to construct the unsaturated sand permeability coefficient model; The stability of the monzonitic granite slope is analyzed by combining the unsaturated sand water retention function model and the unsaturated sand permeability coefficient model to obtain a stability analysis result.

2. The method for analyzing the stability of an unsaturated sandy monzonitic granite slope according to claim 1, wherein: The BC water holding function model is: Where: S e is saturation; b is the inlet pressure value; ψ is the matrix suction; λ is the pore size distribution index; The first correction parameter is: Where: C(ψ) is the first correction parameter; c is the proportional factor; ψ a is the matrix suction corresponding to the completely dry point; ψ c are fitting parameters related to the residual values.

3. The method for analyzing the stability of an unsaturated sandy monzonitic granite slope according to claim 2, wherein: The unsaturated sand water holding function model is: Where: S e is the saturation; C(ψ) is the first correction parameter; ψ b is the inlet pressure value; ψ is the matrix suction; λ is the pore size distribution index.

4. A method for analyzing the stability of an unsaturated sandy monzonitic granite slope according to any one of claims 1 to 3, characterized in that: The BC permeability coefficient model is: Where: k(ψ) is the permeability coefficient; k s is the saturated permeability coefficient; ψ b is the inlet pressure value; ψ is the matrix suction; η=2+3λ; λ is the pore size distribution index; The second correction parameter is: Where: Γ(ψ) is the second correction parameter; ψ r is the residual value; s and t are fitting parameters.

5. The method for analyzing the stability of an unsaturated sandy monzonitic granite slope according to claim 4, wherein: The unsaturated sand permeability coefficient model is: Where: k(ψ) is the permeability coefficient; k s is the saturated permeability coefficient; Γ(ψ) is the second correction parameter; ψ b is the inlet pressure value; ψ is the matrix suction; η=2+3λ; λ is the pore size distribution index.

6. The method for analyzing the stability of an unsaturated sandy monzonitic granite slope according to claim 4 or 5, wherein: The residual value is the matrix suction value corresponding to the intersection of the first tangent line passing through the capillary stage inflection point on the water retention curve and the second tangent line passing through the completely dry point, wherein the inflection point coordinate is (ψ i , S i ), the first tangent is l1, the coordinates of the completely dry point are (a, 0), and the second tangent is l2.

7. The method for analyzing the stability of an unsaturated sandy monzonitic granite slope according to claim 6, wherein: The residual value is solved by the following steps: Derivative the unsaturated sand water retention function model to obtain a first-order derivative water retention function model; In the capillary stage of the water retention curve, the first correction coefficient is equal to one, and the first-order derivative water retention function model is simplified to obtain a first-order derivative capillary stage model; Derivative the first-order derivative capillary stage model to obtain a second-order derivative capillary stage model; The second-order derivative capillary stage model and the unsaturated sand water retention function model are combined to solve and obtain the inflection point coordinates; In the adsorption stage of the water retention curve, the volumetric water content is constant, and the first-order conduction water retention function model is simplified to obtain the first-order conduction adsorption stage model; Combining the inflection point coordinates and the first-order derivative capillary phase model, a first tangent equation is obtained; Combining the coordinates of the completely dry point and the first-order derivative adsorption stage model, a second tangent equation is obtained; The first tangent equation and the second tangent equation are solved simultaneously to obtain the residual value.

8. A method for analyzing the stability of an unsaturated sandy monzonitic granite slope according to any one of claims 1 to 7, characterized in that: The stability analysis results are obtained by the following steps: Based on the unsaturated sand water retention function model and the unsaturated sand permeability coefficient model, a rainfall condition is simulated by numerical simulation to obtain a rainfall simulation result; Based on the rainfall simulation results, coupled stress / pore water pressure was used to analyze the deformation of the monzonitic granite slope and obtain deformation analysis results; Based on the rainfall simulation results, the limit equilibrium method was used to analyze the stability of the monzonitic granite slope and obtain the stability coefficient results; Based on the rainfall simulation results, the pore water pressure distribution of the monzonitic granite slope under natural and rainfall conditions was analyzed to obtain the pore pressure redistribution results; The deformation analysis result, the stability coefficient result and the pore pressure redistribution result are used as the stability analysis result.

9. A storage medium, characterized in that: It contains a series of instructions for executing the method steps according to any one of claims 1 to 8.

10. An unsaturated sandy monzonitic granite slope stability analysis device, characterized in that: The method according to any one of claims 1 to 8 is performed, wherein the device comprises: The water holding function module modifies the BC water holding function model by using the first correction parameter to construct an unsaturated sand water holding function model; The permeability coefficient module modifies the BC permeability coefficient model according to the second correction parameter to construct an unsaturated sand permeability coefficient model; The stability analysis module combines the unsaturated sand water retention function model and the unsaturated sand permeability coefficient model to analyze the stability of the monzonitic granite slope and obtain a stability analysis result.

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