CN109408944A - Expansive soil slope failure by leaking method for analyzing stability based on complete softening intensity - Google Patents
Expansive soil slope failure by leaking method for analyzing stability based on complete softening intensity Download PDFInfo
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Abstract
The invention discloses a kind of expansive soil slope failure by leaking method for analyzing stability based on complete softening intensity, comprising the following steps: live field exploring investigation is carried out to expansive soil slope and obtains soil sample and hydrogeologic data；Expansion soil strength test is carried out to soil sample and obtains physical and mechanical parameter；Depth and saturation height are determined according to hydrogeologic data；According to physical and mechanical parameter and Depth and saturation height, expansive soil slope is modeled, obtains seepage analysis model；The stability analysis come down for the first time to seepage analysis model obtains stability result；Retrogressive failure process simulation is carried out to seepage analysis model and obtains Landslide Features analysis result；Based on the stability for being able to reflect expansive soil slope instability Mechanism and Landslide Features analysis as a result, expansive soil slope is instructed to design and construct.The utility model has the advantages that this method can correctly describe the destructive process of practical expansive soil slope, it is able to reflect expansive soil slope instability Mechanism.
Description
Technical Field
The invention relates to a stability analysis method, in particular to a shallow sliding stability analysis method of an expansive soil side slope based on complete softening strength, and belongs to the field of analysis and application research of geotechnical engineering soil slope stability, especially expansive soil side slope stability.
Background
Because the expansive soil is sensitive to the change of environmental factors, the expansibility and the shear strength of the expansive soil are complex and changeable, and the damage mechanism and the landslide characteristics of the expansive soil slope are different from those of a common soil slope. When the slope stability analysis methods such as the conventional strip division method and the like are adopted to analyze the slope stability of the expansive soil, the calculation result is usually in and out of a larger range from the actual situation in terms of the safety degree and the landslide form, so that the determination of the stability analysis method suitable for the slope of the expansive soil is very important.
The common slope stability analysis method is divided into two types, one is a limit balance method; the other is a finite element method. In order to determine the stability analysis method suitable for the swelling soil slope, numerous scholars improve the limit balance method and the finite element method based on the conventional method and make more efforts.
The method for calculating the expansive soil slope improved by a plurality of scholars is summarized and mainly improved from the following two aspects: firstly, adopting residual strength or dry-wet cycle strength; and secondly, introducing an expansion force, such as applying a conditional force when a limit balance method is adopted and applying a physical force or a facial force when a finite element method is adopted. Although the improved method meets the requirement of the analysis of the stability of the expansive soil slope to a certain extent, the improved method still has defects.
The ultra-consolidation soil has residual strength, the residual strength is adopted only in the analysis of the expansive soil slope stability, no theoretical basis exists, the slope is mainly considered to be damaged for the first time in the analysis of the expansive soil slope stability, and the residual strength is the strength after repeated shearing; the cracks are developed due to dry-wet circulation, and the strength is reduced due to the cracks, so that a student researches the strength of the expansive soil through a dry-wet circulation test, the strength is related to the dry-wet circulation frequency, and the stability analysis adopts the strength under a certain dry-wet circulation frequency. Although the strength can reflect the strength characteristic of the expansive soil under the dry-wet cycle condition, the dry-wet cycle times in the actual environment cannot be defined and can only be artificially controlled indoors; during the analysis of the stability of the expansive soil slope, expansive force is directly introduced in a surface force or physical force mode, the expansive force is applied to the slope as external force, the expansive force belongs to internal force, and the mode of considering the expansive force is not consistent with the actual condition; the landslide of the expansive soil side slope has shallow layer property compared with that of a common soil side slope, the landslide is generated by gradual upward traction after the local damage of a slope toe, and the existing method for analyzing the stability of the expansive soil side slope cannot correctly describe the damage process of the actual expansive soil side slope; for the safety evaluation of the expansive soil side slope, currently, only the safety coefficient during first sliding is used as an evaluation standard of the safety of the expansive soil side slope, actually, the expansive soil side slope landslide has multiple sliding surfaces from bottom to top, and the expansive soil traction type landslide process needs to be researched.
Disclosure of Invention
The invention mainly aims to overcome the defects in the prior art and provide a method for analyzing the shallow sliding stability of the expansive soil slope based on the complete softening strength, which can correctly describe the damage process of the actual expansive soil slope, reflect the instability mechanism of the expansive soil slope and reflect the characteristics of smoothness, shallowness, traction, long-term property, seasonality, directionality and the like of the expansive soil slope.
In order to achieve the purpose, the invention adopts the technical scheme that:
the expansive soil slope shallow layer sliding stability analysis method based on the complete softening strength comprises the following steps of:
1) carrying out on-site field survey investigation on the expansive soil slope to obtain a soil sample and hydrogeological data;
2) performing an expansive soil strength test on the soil sample to obtain physical and mechanical parameters; wherein the expansive soil strength test comprises an undisturbed shear strength test and a complete softening strength test;
3) determining the fracture depth and the height of the infiltration line according to the hydrogeological data;
4) modeling the expansive soil slope according to physical and mechanical parameters, the depth of the crack and the height of the infiltration line to obtain a seepage analysis model;
5) carrying out stability analysis on the seepage analysis model for the first landslide to obtain a stability result;
6) carrying out traction type progressive destruction process simulation on the seepage analysis model to obtain a landslide characteristic analysis result;
7) and guiding the design and construction of the expansive soil slope based on a stability result capable of reflecting the instability mechanism of the expansive soil slope and a landslide characteristic analysis result.
The invention is further configured to: the field on-site survey investigation in the step 1) comprises the steps of arranging the hydrogeological data on the field and sampling the soil on the field.
The invention is further configured to: the undisturbed shear strength test in the step 2) is specifically that an undisturbed expansive soil sample which is not weathered is taken to perform a shear strength test under the condition of saturated consolidation and no drainage, and shear strength parameters under the condition of saturated consolidation and no drainage of the soil sample are obtained according to test results and are respectively in an undisturbed stateCohesion force c0And the original internal friction angle
The invention is further configured to: the complete softening strength test in the step 2) is specifically to take an original-state expansive soil sample which is not weathered to perform a complete softening strength test, and obtain shear strength parameters of the soil sample under the complete softening condition according to test results, wherein the shear strength parameters are respectively complete softening cohesive force cfAnd a fully softened internal friction angle
The invention is further configured to: determining the fracture depth in the step 3), namely determining the development depth of the fracture area as the fracture depth h according to the hydrogeological datacSpecifically, the maximum depth which can be expected to be reached by the crack in the design service life is taken as the crack depth h for the temporary slopecFor a permanent slope, the maximum depth which can be reached by the crack is taken as the crack depth hc(ii) a Or for existing slopes with the formation time of the surveyed soil layer reaching the development age, acquiring the fracture depth according to the actually measured data as the surface layer fractures develop to be mature so as to meet the representative requirement of the survey data; for newly excavated or newly filled side slopes, if the survey data is not representative because the cracks in the survey soil layer are still in the development stage, the crack depth is 4m according to the survey statistical data of the nearby soil layer.
The invention is further configured to: determining the height of the wetting line in the step 3), specifically,
for the existing side slope with the formation time of the survey soil layer reaching the development age, monitoring and determining the height position actually reached by the saturation line as the height of the saturation line by burying a monitoring instrument on site;
for newly excavated or newly filled side slopes, the approximate estimated height position is taken as the height of the saturation line through survey statistical data of nearby soil layers;
wherein, the height of the infiltration line is the position of the toe of the slope or the position of the top of the slope which is actually reached along the distribution of the slope.
The invention is further configured to: the modeling of the expansive soil slope in the step 4) is specifically,
4-1) establishing a slope geometric model;
4-2) carrying out partition processing on the side slope in the side slope geometric model according to the fracture depth;
dividing the slope into 3 layers along the depth direction, wherein the first layer is a crack fully-developed layer with the depth of 2hcA/3; the second layer is a layer with insufficient crack development, and the depth is hcA/3; the third layer is a non-fracture area; the first layer and the second layer form a fracture zone;
4-3) carrying out soil body strength assignment on different subareas;
for the fracture zone, take the completely softened cohesion cfAnd a fully softened internal friction angleAssigning the shear strength parameter of the soil body of the full development layer of the crack, and taking the undisturbed cohesion c0And complete softening-like cohesion force cfAverage value of and original internal friction angleAngle of internal friction with fully softened stateThe average value of the values is assigned to the shear strength parameter of the soil body of the fracture insufficient development layer, and then the cohesive force of the fracture insufficient development layerInternal friction angle of crack underdeveloped layer
For non-fractured regions, the original cohesive force c is taken0And the original internal friction angleAssigning the shear strength parameter of the soil body in the non-fracture area;
wherein the original cohesive force c0And the original internal friction angleShear strength parameter under the condition of saturated consolidation and no drainage of the soil sample, and completely softened cohesive force cfAnd a fully softened internal friction angleThe shear strength parameter is the shear strength parameter of the soil sample under the condition of complete softening;
4-4) setting the position of the saturation line according to the height of the saturation line, calculating the slip moment of the soil body below the saturation line by adopting saturated volume weight, and calculating the anti-slip moment of the soil body below the saturation line by adopting floating volume weight;
and 4-5) carrying out soil body strength assignment and saturation line position setting on the slope geometric model, and reconstructing to obtain a seepage analysis model.
The invention is further configured to: the stability analysis is to consider deep sliding, shallow sliding, local sliding and integral sliding, select a sliding arc type for a slope toe in the seepage analysis model, and check and calculate dangerous sliding arcs of the expansive soil slope instability; further checking and calculating the unstable infiltration line position of the expansive soil slope based on different infiltration line heights and different sliding arc types; wherein, deep sliding means that the sliding surface is deep below the depth of the crack, and shallow sliding means that the sliding surface is limited within the depth of the crack.
The invention is further configured to: simulating a traction type progressive destruction process in the step 6), specifically, removing a landslide body after the first landslide occurs; wherein the first landslide is formed into stable seepage at the toe due to rainwater gathering; and after the slope foot slides, performing secondary stability analysis, and so on until the slide slope develops to the top of the slope.
Compared with the prior art, the invention has the beneficial effects that:
the method provided by the invention starts from the aspects of partitioning the side slope soil layer, dereferencing the soil body strength parameter, determining the saturation line and the like, analyzes the stability of the expansive soil side slope by adopting a seepage model which can reflect the complete softening strength and reasonable seepage of the crack influence to carry out the calculation of a limit balance method, can simulate the progressive failure process of the expansive soil side slope, can reflect the instability mechanism of the expansive soil side slope according to the calculation result, and can embody the characteristics of smoothness, shallowness, traction, long-term property, seasonality, directivity and the like of the expansive soil side slope landslide.
The foregoing is only an overview of the technical solutions of the present invention, and in order to more clearly understand the technical solutions of the present invention, the present invention is further described below with reference to the accompanying drawings.
Drawings
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a schematic illustration of determining fracture depth in the method of the present invention;
FIG. 3 is a schematic illustration of determining a variation of a wetting line in the method of the present invention;
FIG. 4 is a schematic illustration of determining the height of a wetting line in the method of the present invention;
FIG. 5 is a schematic illustration of a side slope section in the method of the present invention;
fig. 6 is a schematic view of the progressive slope destruction of the method of the present invention.
Detailed Description
The invention is further described with reference to the accompanying drawings.
The invention provides a method for analyzing the sliding stability of a shallow layer of an expansive soil slope based on complete softening strength, which comprises the following steps of:
1) and carrying out on-site survey investigation on the expansive soil slope to obtain a soil sample and hydrogeological data.
The field survey comprises the steps of arranging hydrogeological data of a field and sampling soil of the field.
2) Performing an expansive soil strength test on the soil sample to obtain physical and mechanical parameters; wherein the expansive soil strength test comprises an undisturbed shear strength test and a complete softening strength test;
an original state shear strength test is carried out, specifically, an original state expansive soil sample which is not weathered is taken to carry out a shear strength test under the condition of saturated consolidation and no drainage, and shear strength parameters under the condition of saturated consolidation and no drainage of the soil sample are obtained according to test results, and are respectively original state cohesive force c0And the original internal friction angle
A complete softening strength test, specifically, taking an original-state expansive soil sample which is not weathered to perform the complete softening strength test, and acquiring the shear strength parameters of the soil sample under the complete softening condition according to the test results, wherein the shear strength parameters are respectively the complete softening cohesion cfAnd a fully softened internal friction angleThe soil sample is subjected to a complete softening strength test to obtain the complete softening strength parameter required by calculation.
3) And determining the fracture depth and the height of the infiltration line according to the hydrogeological data.
Determining the depth of the fracture, namely determining the development depth of the fracture area as the depth h of the fracture according to the hydrogeological datacSpecifically, the maximum depth which can be expected to be reached by the crack in the design service life is taken as the crack depth h for the temporary slopecFor a permanent slope, the maximum depth which can be reached by the crack is taken as the crack depth hc(ii) a The temporary side slope is a side slope which is not used after being used for a short time after being excavated, and the permanent side slope is a side slope which is used for a long time;
or,
for existing slopes with the formation time of the surveyed soil layer reaching the development age, as the surface layer cracks develop to be mature, the survey data have representative requirements, and then the crack depth is taken according to the actually measured data, as shown in fig. 2; for newly excavated or newly filled side slopes, if the survey data is not representative because the cracks in the survey soil layer are still in the development stage, the crack depth is 4m according to the survey statistical data of the nearby soil layer.
Under the influence of seepage, the seepage formed by rainfall infiltration in a slope body is an important influence factor for landslide of the expansive soil side slope. Rainwater at the toe of the slope gathers and reduces the intensity of the soil body on the one hand, and on the other hand, the rainwater generates obvious seepage force when stable seepage is formed, so that the toe of the slope is easy to slide to form a local landslide, and the schematic diagram of the change of a seepage line is shown in fig. 3; the position of the saturation line is related to the rainfall intensity in time, and under the conditions of high intensity and long time, the height of the saturation line can reach the top of the slope, and the saturation line is along the whole slope surface; under the general condition of rainfall intensity and duration, rainwater toe gathers and forms the seepage flow, and the infiltration line height is located near the toe, therefore the position of infiltration line has certain mobility and randomness.
Determining the height of the wetting line, as shown in FIG. 4wIn particular, the method comprises the following steps of,
for the existing side slope with the formation time of the survey soil layer reaching the development age, monitoring and determining the height position actually reached by the saturation line as the height of the saturation line by burying a monitoring instrument on site;
for newly excavated or newly filled side slopes, the approximate estimated height position is taken as the height of the saturation line through survey statistical data of nearby soil layers;
wherein, the height of the infiltration line is the position of the toe of the slope or the position of the top of the slope which is actually reached along the distribution of the slope.
4) And modeling the expansive soil slope according to the physical and mechanical parameters, the fracture depth and the height of the infiltration line to obtain a seepage analysis model.
The expansive soil slope is modeled, specifically,
4-1) establishing a slope geometric model;
4-2) carrying out partition processing on the side slope in the side slope geometric model according to the fracture depth;
dividing the slope into 3 layers along the depth direction, as shown in FIG. 5, the first layer is a crack fully-developed layer with a depth of 2hcA/3; the second layer is a layer with insufficient crack development, and the depth is hcA/3; the third layer is a non-fracture area; the first layer and the second layer form a fracture zone;
4-3) carrying out soil body strength assignment on different subareas;
for the fracture zone, take the completely softened cohesion cfAnd a fully softened internal friction angleAssigning the shear strength parameter of the soil body of the full development layer of the crack, and taking the undisturbed cohesion c0And complete softening-like cohesion force cfAverage value of and original internal friction angleAngle of internal friction with fully softened stateThe average value of the values is assigned to the shear strength parameter of the soil body of the fracture insufficient development layer, and then the cohesive force of the fracture insufficient development layerInternal friction angle of crack underdeveloped layer
For non-fractured regions, the original cohesive force c is taken0And the original internal friction angleAssigning the shear strength parameter of the soil body in the non-fracture area;
wherein the original cohesive force c0And the original internal friction angleShear strength parameter under the condition of saturated consolidation and no drainage of the soil sample, and completely softened cohesive force cfAnd a fully softened internal friction angleThe shear strength parameter is the shear strength parameter of the soil sample under the condition of complete softening;
4-4) setting the position of the saturation line according to the height of the saturation line, calculating the slip moment of the soil body below the saturation line by adopting saturated volume weight, and calculating the anti-slip moment of the soil body below the saturation line by adopting floating volume weight;
and 4-5) carrying out soil body strength assignment and saturation line position setting on the slope geometric model, and reconstructing to obtain a seepage analysis model.
And 4) calculating the slope stability by adopting a limit balance method after modeling.
5) And carrying out stability analysis on the seepage analysis model for the first landslide to obtain a stability result.
The stability analysis is to consider deep sliding, shallow sliding, local sliding and integral sliding, select a sliding arc type for a slope toe in the seepage analysis model, and check and calculate dangerous sliding arcs of the expansive soil slope instability; further checking and calculating the unstable infiltration line position of the expansive soil slope based on different infiltration line heights and different sliding arc types; wherein, deep sliding means that the sliding surface is deep below the depth of the crack, and shallow sliding means that the sliding surface is limited within the depth of the crack.
Because the sliding body for deep sliding is large in volume and large in sliding moment, if the strength index difference between a crack area and a non-crack area is not very obvious, dangerous deep sliding can exist. Deep sliding may also occur if there are other soil layers below that have low strength, or significant deep soft zones. Thus, while expansive soil slope instability is generally shallow, deep glide planes are still considered. The deep sliding calculation is common to the method and the traditional method, and the method can calculate the deep sliding and is more remarkable in that the shallow sliding can be calculated.
6) And (5) carrying out traction type progressive destruction process simulation on the seepage analysis model to obtain a landslide characteristic analysis result.
Simulating a traction type progressive destruction process, specifically, removing a landslide body after the first landslide occurs; wherein the first landslide is formed into stable seepage at the toe due to rainwater gathering; and after the slope foot slides, performing secondary stability analysis, and so on until the slide slope develops to the top of the slope. As shown in fig. 6, fig. 6- (a) is a schematic view of a first landslide, fig. 6- (b) is a schematic view of a second landslide, fig. 6- (c) is a schematic view of a third landslide, fig. 6- (d) is a schematic view of a fourth landslide, fig. 6- (e) is a schematic view of a fifth landslide, fig. 6- (f) is a schematic view of a sixth landslide, fig. 6- (g) is a schematic view of a seventh landslide, and fig. 6- (h) is a schematic view of an overall view of a landslide. Landslide of the expansive soil slope is a typical traction type damage process, the stability analysis of the first landslide in the step 5) is the analysis of the first damage of the slope toe of the slope, and the first damage provides a foundation for the traction damage in the subsequent step 6); the simulation of the progressive destruction process is a part of the whole stability analysis, namely firstly destroying, and then destroying by traction, wherein the first destroying and the destroying by traction are the whole process of the side slope destruction of the expansive soil; and 6) obtaining the overall safety coefficient and the final landslide form of the expansive soil side slope, and using the result in the step 7) for guiding design construction.
7) And guiding the design and construction of the expansive soil slope based on a stability result capable of reflecting the instability mechanism of the expansive soil slope and a landslide characteristic analysis result.
The method has the innovation points that starting from the aspects of side slope soil layer partition, soil body strength parameter value taking, saturation line determination and the like, the ultimate balance method calculation is carried out by adopting a seepage model capable of reflecting the complete softening strength and reasonable seepage of crack influence, the stability of the expansive soil side slope is analyzed, and finally the analysis result of the stability, including the safety coefficient and the landslide characteristic, can be obtained, correctly describe the damage process of the actual expansive soil side slope and reflect the instability mechanism of the expansive soil side slope, so that the method is beneficial to guiding the design and construction of the expansive soil side slope and solves the problem that the analysis result of the traditional analysis method cannot correctly reflect the safety and the landslide characteristic of the actual expansive soil side slope during the stability analysis of the expansive soil side slope.
The foregoing illustrates and describes the principles, general features, and advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (9)
1. A method for analyzing the shallow sliding stability of an expansive soil slope based on complete softening strength is characterized by comprising the following steps:
1) carrying out on-site field survey investigation on the expansive soil slope to obtain a soil sample and hydrogeological data;
2) performing an expansive soil strength test on the soil sample to obtain physical and mechanical parameters; wherein the expansive soil strength test comprises an undisturbed shear strength test and a complete softening strength test;
3) determining the fracture depth and the height of the infiltration line according to the hydrogeological data;
4) modeling the expansive soil slope according to physical and mechanical parameters, the depth of the crack and the height of the infiltration line to obtain a seepage analysis model;
5) carrying out stability analysis on the seepage analysis model for the first landslide to obtain a stability result;
6) carrying out traction type progressive destruction process simulation on the seepage analysis model to obtain a landslide characteristic analysis result;
7) and guiding the design and construction of the expansive soil slope based on a stability result capable of reflecting the instability mechanism of the expansive soil slope and a landslide characteristic analysis result.
2. The method for analyzing the shallow sliding stability of the expansive soil slope based on the full softening strength as claimed in claim 1, wherein: the field on-site survey investigation in the step 1) comprises the steps of arranging the hydrogeological data on the field and sampling the soil on the field.
3. The method for analyzing the shallow sliding stability of the expansive soil slope based on the full softening strength as claimed in claim 1, wherein: the original-state shear strength test in the step 2) is specifically to take an original-state expansive soil sample which is not weathered to perform a shear strength test under the condition of saturated consolidation and no drainage, and obtain shear strength parameters under the condition of saturated consolidation and no drainage of the soil sample according to test results, wherein the shear strength parameters are original-state cohesion c0And the original internal friction angle
4. The method for analyzing the shallow sliding stability of the expansive soil slope based on the full softening strength as claimed in claim 1, wherein: the complete softening strength test in the step 2) is specifically to take an original expansive soil sample which is not weathered to perform the complete softening strength test, and obtain the shear strength parameters of the soil sample under the complete softening condition according to the test results, wherein the shear strength parameters are respectively completeFull softening type cohesion force cfAnd a fully softened internal friction angle
5. The method for analyzing the shallow sliding stability of the expansive soil slope based on the full softening strength as claimed in claim 1, wherein: determining the fracture depth in the step 3), namely determining the development depth of the fracture area as the fracture depth h according to the hydrogeological datacSpecifically, the maximum depth which can be expected to be reached by the crack in the design service life is taken as the crack depth h for the temporary slopecFor a permanent slope, the maximum depth which can be reached by the crack is taken as the crack depth hc(ii) a Or for existing slopes with the formation time of the surveyed soil layer reaching the development age, acquiring the fracture depth according to the actually measured data as the surface layer fractures develop to be mature so as to meet the representative requirement of the survey data; for newly excavated or newly filled side slopes, if the survey data is not representative because the cracks in the survey soil layer are still in the development stage, the crack depth is 4m according to the survey statistical data of the nearby soil layer.
6. The method for analyzing the shallow sliding stability of the expansive soil slope based on the full softening strength of claim 5, wherein: determining the height of the wetting line in the step 3), specifically,
for the existing side slope with the formation time of the survey soil layer reaching the development age, monitoring and determining the height position actually reached by the saturation line as the height of the saturation line by burying a monitoring instrument on site;
for newly excavated or newly filled side slopes, the approximate estimated height position is taken as the height of the saturation line through survey statistical data of nearby soil layers;
wherein, the height of the infiltration line is the position of the toe of the slope or the position of the top of the slope which is actually reached along the distribution of the slope.
7. The method for analyzing the shallow sliding stability of the expansive soil slope based on the full softening strength of claim 6, wherein: modeling the expansive soil side slope in the step 4), specifically, 4-1) establishing a side slope geometric model;
4-2) carrying out partition processing on the side slope in the side slope geometric model according to the fracture depth;
dividing the slope into 3 layers along the depth direction, wherein the first layer is a crack fully-developed layer with the depth of 2hcA/3; the second layer is a layer with insufficient crack development, and the depth is hcA/3; the third layer is a non-fracture area; the first layer and the second layer form a fracture zone;
4-3) carrying out soil body strength assignment on different subareas;
for the fracture zone, take the completely softened cohesion cfAnd a fully softened internal friction angleAssigning the shear strength parameter of the soil body of the full development layer of the crack, and taking the undisturbed cohesion c0And complete softening-like cohesion force cfAverage value of and original internal friction angleAngle of internal friction with fully softened stateThe average value of the values is assigned to the shear strength parameter of the soil body of the fracture insufficient development layer, and then the cohesive force of the fracture insufficient development layerInternal friction angle of crack underdeveloped layer
For non-fractured regions, the original cohesive force c is taken0And the original internal friction angleAssigning the shear strength parameter of the soil body in the non-fracture area;
wherein the original cohesive force c0And the original internal friction angleShear strength parameter under the condition of saturated consolidation and no drainage of the soil sample, and completely softened cohesive force cfAnd a fully softened internal friction angleThe shear strength parameter is the shear strength parameter of the soil sample under the condition of complete softening;
4-4) setting the position of the saturation line according to the height of the saturation line, calculating the slip moment of the soil body below the saturation line by adopting saturated volume weight, and calculating the anti-slip moment of the soil body below the saturation line by adopting floating volume weight;
and 4-5) carrying out soil body strength assignment and saturation line position setting on the slope geometric model, and reconstructing to obtain a seepage analysis model.
8. The method for analyzing the shallow sliding stability of the expansive soil slope based on the full softening strength as claimed in claim 1, wherein: the stability analysis is to consider deep sliding, shallow sliding, local sliding and integral sliding, select a sliding arc type for a slope toe in the seepage analysis model, and check and calculate dangerous sliding arcs of the expansive soil slope instability; further checking and calculating the unstable infiltration line position of the expansive soil slope based on different infiltration line heights and different sliding arc types; wherein, deep sliding means that the sliding surface is deep below the depth of the crack, and shallow sliding means that the sliding surface is limited within the depth of the crack.
9. The method for analyzing the shallow sliding stability of the expansive soil slope based on the full softening strength of claim 8, wherein: simulating a traction type progressive destruction process in the step 6), specifically, removing a landslide body after the first landslide occurs; wherein the first landslide is formed into stable seepage at the toe due to rainwater gathering; and after the slope foot slides, performing secondary stability analysis, and so on until the slide slope develops to the top of the slope.
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