Urban slope stability characteristic analysis method and system based on block gliding risk

Abstract

The invention belongs to the technical field of geological disasters, and discloses an urban slope stability characteristic analysis method and system based on a block gliding risk, and the method comprises the steps: calculating the stability characteristic of each station based on a plane gliding method through measuring the slope size, soil and vegetation characteristics and other data; the relationship between the stability coefficient and each sensitive factor is analyzed, and the research result shows that the slope stability coefficient of each sampling point is basically more than 1.0, and the landslide risk is extremely low; the soil cohesive force has the greatest contribution in maintaining the stability of the slope and is most sensitive to the stability coefficient of the slope; the soil water content can reduce the slope stability coefficient from the aspects of increasing the self weight of the soil body, reducing the soil cohesive force and the like; the soil root system density can improve the overall stability of the slope from the aspects of enhancing the shear strength of soil, reducing soil erosion and the like. Soil is reinforced through vegetation concrete and other technologies, meanwhile, the slope vegetation coverage rate is increased, and regular monitoring of the midsole risky slope state is a good method for reducing the landslide risk of the midsole risky slope.

Description

Technical Field

[0001] The present invention belongs to the technical field of geological disasters, and in particular relates to a method and system for analyzing the stability characteristics of urban slopes based on the risk of block sliding. Background Art

[0002] With the acceleration of global urbanization and the continuous increase in human engineering activities, if the remaining slopes after land excavation in urban construction are not properly handled, slope instability will occur from time to time, causing varying degrees of economic losses and casualties. There are many factors that cause slope instability, mainly natural factors such as rainfall, earthquakes, and weathering, as well as human activities such as mining and road construction. Under the background of global climate change, the frequent occurrence of extreme climate events such as heavy rains and droughts will also have a complex impact on slope stability, increasing the likelihood of secondary disasters such as landslides and mudslides. Through the study and evaluation of slope stability characteristics, various disasters caused by slope instability can be effectively prevented and mitigated, the safety of human activities and the sustainability of economic development can be guaranteed, and a scientific basis can be provided for mining planning and engineering design in urban construction, which has important research significance.

[0003] Slope stability is affected by a variety of natural and human factors, among which vegetation and rainfall are two key natural factors. The root structure of vegetation plays an important role in stabilizing the slope by increasing the shear strength of the soil and reducing surface erosion. Studies have found that different types of vegetation have different effects on improving soil stability. The deep roots of trees are more effective than the shallow roots of herbaceous plants in enhancing soil cohesion. In addition, vegetation coverage can effectively reduce surface runoff and rainfall infiltration, reducing the risk of slope landslides. Rainfall is one of the main natural factors that induce slope instability. Some studies have found the effects of rainfall intensity and duration on soil pore water pressure and slope stability through field observations and numerical simulations. During rainfall, the saturation of the soil increases, resulting in an increase in pore water pressure, reducing the effective stress of the soil, and thus reducing the stability of the slope. Some researchers have developed a variety of early warning systems for rainfall-induced landslides, which can monitor parameters such as rainfall and soil moisture to assess the risk of slope instability in real time. The calculation and evaluation methods of slope stability mainly include the limit equilibrium method based on theoretical analysis and the finite element method based on numerical simulation. The limit equilibrium method calculates the safety factor of the slope by analyzing the mechanical equilibrium state of the potential sliding surface, while the finite element method uses numerical simulation technology to more accurately simulate the stability of slopes under complex geological conditions. In addition, emerging three-dimensional numerical simulation technology and prediction models based on machine learning have been widely used in slope stability assessment.

[0004] Through the above analysis, the problems and defects of the prior art are as follows:

[0005] In urban construction, the instability of the slopes left over from land excavation often occurs, and the existing technology cannot analyze it in time, leading to landslide disasters. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a method for analyzing the stability characteristics of urban slopes based on the risk of block sliding.

[0007] The present invention is implemented in this way: a method for analyzing the characteristics of urban slope stability based on the risk of block sliding includes:

[0008] Step 1, by measuring the slope dimensions, soil and vegetation characteristics data, the stability characteristics of each site are calculated based on the plane sliding method;

[0009] Step 2: Analyze the relationship between the stability coefficient and each sensitive factor.

[0010] Further, the method of measuring slope dimensions, soil and vegetation characteristic data is as follows:

[0011] For each slope, the main sampling or measurement indicators include: geometric dimensions of the slope, soil properties and vegetation characteristics data;

[0012] The geometric dimensions of the slope are directly measured on site; the soil moisture content is measured using a tensiometer method, and the measured pore water pressure is converted using a theoretical formula to obtain the mass moisture content of the soil;

[0013] The soil type ratio and the volume ratio of vegetation roots in the soil were estimated by field sampling and laboratory screening. The dominant vegetation ratio was estimated by field plot survey, i.e., a representative 1m 2 Sample plots were taken and the growth area proportion of different types of vegetation was determined.

[0014] Furthermore, the method for calculating the stability characteristics of each site based on the plane sliding method is as follows:

[0015] The plane sliding method is mainly used to analyze the stability characteristics of different types of soil or gravel along an approximately plane sliding surface; its stability coefficient Fs can be expressed as the ratio between the shear strength R of the potential landslide body and the sliding force T under gravity, that is,

[0016]

[0017] Wherein, c represents the effective cohesion coefficient of soil, in kPa, which is estimated in the model according to the effective cohesion of different types of soil and the proportion of soil types at the field survey points; L represents the length of the sliding surface, in m; W represents the weight of the landslide, in kN, which is calculated by the length L and height H of the potential landslide body, including the soil and interstitial water of the landslide body; α represents the angle between the sliding surface L and the horizontal plane, in radians; Pwp represents the pore water pressure on the sliding surface, in kPa, which is related to the water content m of the soil; γ represents the effective internal friction angle of soil, in radians, and the calculation method is similar to the effective cohesion, that is, it is estimated according to the effective internal friction angle of different types of soil and the proportion of soil types at the field survey points; cr represents the root enhancement coefficient, that is, considering the contribution of vegetation roots to slope stability, and its calculation method refers to Stokes as follows,

[0018]

[0019] Where RAR represents the root volume ratio, dimensionless; It represents the root growth angle relative to the sliding surface, in radians. In this paper, it is assumed that the average root growth angle is vertically downward. T r It represents the root damage strength, in kPa. The calculation method is to first determine the proportion of the first three dominant vegetation types at the sampling point, RV, and then use the tensile test to measure the root damage strength TrV of each dominant vegetation type, that is, the ratio of the maximum tensile force that the root system can withstand to the root diameter. Finally, the area ratio coefficient AR of the vegetation is considered, that is,

[0020] T r =AR·∑RV·TrV#(3)

[0021] According to the above calculation method, the stability coefficient can actually be divided into three parts, namely

[0022] Fs=Fs c +Fs w +Fs t #(4)

[0023] in represents the contribution of soil cohesion to stability, represents the contribution of the slope's deadweight to stability, Represents the contribution of vegetation cover and root system to stability.

[0024] Another object of the present invention is to provide a system for analyzing the characteristics of urban slope stability based on the risk of block sliding, comprising:

[0025] The measurement module is used to calculate the stability characteristics of each site based on the plane sliding method by measuring slope dimensions, soil and vegetation characteristics data;

[0026] The analysis module is used to analyze the relationship between the stability coefficient and each sensitive factor.

[0027] Another object of the present invention is to provide a computer device, which includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the urban slope stability characteristic analysis method based on the risk of block sliding.

[0028] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to execute the steps of the urban slope stability characteristic analysis method based on block sliding risk.

[0029] Another object of the present invention is to provide an information data processing terminal, which is used to implement the urban slope stability characteristic analysis system based on block sliding risk.

[0030] Another object of the present invention is to provide an urban slope stability analysis system based on block sliding risk, characterized in that the system comprises:

[0031] Data collection module, used to collect slope geometry, soil characteristics and vegetation characteristics data, including soil moisture content, soil type, vegetation root volume ratio and dominant vegetation ratio;

[0032] The calculation module calculates the stability coefficient of the slope based on the plane sliding method and determines the contribution of soil cohesion, slope deadweight, vegetation root system, etc. to stability;

[0033] The analysis module is used to analyze the relationship between the slope stability coefficient and various sensitive factors and predict the potential landslide risk of the slope.

[0034] Another object of the present invention is to provide an urban slope stability measurement device, characterized in that it includes:

[0035] Tensiometer sensor, used to measure the pore water pressure in the slope soil and convert it into soil mass water content through theoretical formula;

[0036] Sampling equipment for collecting soil samples and vegetation root samples and determining soil type ratios and vegetation root volume ratios;

[0037] The data processing module performs real-time analysis on the measurement data and provides real-time assessment of slope stability and landslide risk.

[0038] Another object of the present invention is to provide a device for predicting the risk of landslides on urban slopes, characterized in that the device comprises:

[0039] Slope geometry measurement module, used to determine the length, height and slope of the slope;

[0040] Soil and vegetation characteristics detection module, used to analyze soil cohesion coefficient, internal friction angle and vegetation root enhancement coefficient;

[0041] The landslide stability calculation module uses the plane sliding method to calculate the stability coefficient of the slope based on the measured data, and outputs the stability analysis results for landslide risk prediction.

[0042] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0043] First, the present invention uses the plane sliding method to calculate the stability characteristics of each slope, and analyzes the relationship between slope stability and sensitive factors such as soil cohesion, soil moisture content, and vegetation root characteristics. The paper obtains the following conclusions.

[0044] (1) The slope stability coefficients of all sampling points are basically above 1.0, indicating that the landslide risk is extremely small;

[0045] (2) Soil cohesion contributes the most to maintaining slope stability. When the soil cohesion coefficient increases by 20%, its stability coefficient can be increased by up to 31.2%;

[0046] (3) Soil moisture content increases soil deadweight and reduces soil cohesion, and is therefore negatively correlated with the slope stability coefficient;

[0047] (4) Soil root density can improve the overall stability of the slope by enhancing the soil's shear strength and reducing soil erosion.

[0048] Second, the urban slope stability characteristic analysis method based on block sliding risk provided by the present invention solves several key problems in the prior art in industrial applications and has achieved significant technological progress.

[0049] Existing technical problems:

[0050] 1. Insufficient data collection: Traditional slope stability analysis methods usually rely on limited geological survey data, ignoring factors such as vegetation coverage and soil moisture content that have an important impact on slope stability, resulting in a lack of comprehensiveness and accuracy in the analysis results.

[0051] 2. The analysis method is single and lacks accuracy: Most of the existing slope stability analysis methods use simplified models, ignoring the in-depth analysis of sensitive factors, making it difficult to accurately reflect the actual stability of the slope, especially in complex urban environments, resulting in the inability to effectively predict and prevent potential landslide risks.

[0052] 3. Lack of comprehensive evaluation of influencing factors: Traditional methods usually fail to systematically analyze and quantify the factors affecting slope stability, and cannot provide targeted suggestions for slope management, which affects the scientificity and effectiveness of slope protection measures.

[0053] Technical advances of the present invention:

[0054] 1. Comprehensive data collection and processing: This invention forms a comprehensive data set by measuring multiple factors such as slope size, soil characteristics, vegetation cover, etc., providing rich basic data for slope stability analysis. Through the comprehensive processing of these data, the accuracy of slope stability analysis is significantly improved.

[0055] 2. Application of multi-factor analysis model: This paper adopts the plane sliding method combined with multi-sensitive factor analysis to perform detailed calculation and evaluation of slope stability. By quantitatively analyzing the relationship between the stability coefficient and the sensitive factor, the influence of each factor on the slope stability is clarified, and high-risk areas can be identified more accurately.

[0056] 3. Slope management measures with strong guidance: Based on the analysis results of sensitive factors, the present invention can put forward targeted slope management suggestions, such as improving the drainage system, increasing vegetation coverage, etc., which greatly enhances the scientific nature and effect of slope management and reduces the probability of geological disasters such as landslides.

[0057] 4. Efficient and practical urban applications: This method is particularly suitable for complex urban environments. It can quickly and efficiently analyze the stability of urban slopes and provide decision support for urban planning and construction projects. Compared with traditional methods, it significantly improves the accuracy and reliability of slope stability analysis, which helps to ensure the safety and sustainability of urban infrastructure.

[0058] In summary, the present invention has made significant progress in solving the problems of incomplete data collection, single analysis method and lack of comprehensive evaluation of influencing factors in the prior art, and provides a more scientific, comprehensive and effective solution for urban slope stability analysis.

[0059] Third, the expected benefits and commercial value of the technical solution of the present invention after transformation are:

[0060] The present invention calculates the stability of the slope by utilizing the risk of block sliding. The expected benefits and commercial value of the technical solution after transformation are mainly reflected in civil engineering and geological disaster prevention and control, providing a method for rapid calculation and judgment of slope stability. First, in civil engineering, the present invention can be applied to the slope stability assessment in the construction of highways, railways, water conservancy and other projects, providing reliable data support for engineering design and construction. Secondly, in terms of low-quality disasters, the present invention can be used for monitoring and early warning to reduce the loss of life and property when disasters occur.

[0061] The technical solution of the present invention fills the technical gap in the industry at home and abroad:

[0062] The present invention combines effective cohesion, slope weight and vegetation root reinforcement. Compared with the traditional slope stability assessment method, this method considers more comprehensive factors. Compared with the currently popular finite element numerical simulation method, although the calculation accuracy of this method is not as good as the former, the calculation efficiency is higher and it is suitable for the predictive evaluation of large-scale and multiple slopes.

[0063] (3) The technical solution of the present invention overcomes technical prejudice:

[0064] The technical solution of the present invention overcomes the limitations and biases of traditional slope stability assessment methods. Traditional methods usually focus on analyzing a single factor, such as the mechanical properties of the soil, the geometry of the slope, or groundwater conditions, and lack comprehensive consideration of other important influencing factors. These methods often cannot fully reflect the true stability of the slope and are prone to deviations. The present invention combines three key factors: effective cohesion, the weight of the slope itself, and the enhancement of the vegetation root system, providing a more comprehensive assessment perspective.

[0065] At the same time, the present invention also overcomes the high threshold problem of modern finite element numerical simulation methods. Although the finite element method can provide accurate slope stability analysis, it requires high professional knowledge and modeling skills of the user, and it is difficult for non-professionals to master it. The method of the present invention is simple and easy to use, and the evaluation process does not require complex numerical modeling and advanced software support, which reduces the difficulty of application and enables non-professional users to effectively perform slope stability evaluation, thereby expanding the scope of application of the technology.

[0066] Fourth, the technical solution of the present invention solves many problems in the existing urban slope stability analysis technology in industrial applications and has achieved significant technical progress, which is mainly reflected in the following aspects:

[0067] 1. Accuracy and comprehensiveness of data collection: Traditional slope stability assessment methods usually rely on simple geometric measurements and soil analysis, and tend to ignore the impact of slope vegetation on stability. The present invention uses a systematic measurement device to accurately collect slope geometry, soil properties, and vegetation characteristics data, especially considering the enhancement of slope stability by vegetation roots, thereby enhancing the accuracy and completeness of the assessment.

[0068] 2. Stability calculation based on plane sliding method: The present invention adopts plane sliding method, combining soil cohesion, internal friction angle, pore water pressure and other factors to comprehensively calculate the stability coefficient of the slope. Compared with the traditional method, the calculation model of the present invention refines the contribution of each factor and can accurately assess the sliding risk of the slope under different conditions, which is particularly suitable for the stability analysis of urban slopes under complex geological conditions.

[0069] 3. Real-time monitoring and dynamic adjustment: By introducing a sensor network, slope data can be collected in real time, and real-time analysis and risk prediction of slope stability can be performed through an online calculation module. This real-time monitoring and dynamic adjustment function enables the present invention to quickly reflect changes in the slope environment, effectively improving the accuracy of slope monitoring and emergency handling capabilities.

[0070] 4. Multi-factor comprehensive analysis and risk assessment: This invention not only considers the physical characteristics of the slope, but also incorporates the vegetation root system and hydrological factors into the stability analysis model, greatly enriching the elements of slope landslide risk assessment. Through comprehensive analysis of various sensitive factors (such as soil moisture content, vegetation root system, etc.), high-risk areas can be accurately identified, improving the reliability and scientificity of urban slope protection.

[0071] In summary, the present invention significantly improves the accuracy of data collection, the comprehensiveness and real-time performance of stability assessment in slope stability analysis, and provides more reliable and intelligent technical support for urban construction and slope protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 It is a flow chart of a method for analyzing characteristics of urban slope stability based on block sliding risk provided by an embodiment of the present invention.

[0073] Figure 2 It is a structural block diagram of an urban slope stability characteristic analysis system based on block sliding risk provided by an embodiment of the present invention.

[0074] Figure 3 This is a sampling location distribution diagram provided by an embodiment of the present invention.

[0075] Figure 4 This is a schematic diagram of a potential landslide body taking into account the strengthening effect of vegetation roots provided by an embodiment of the present invention.

[0076] Figure 5 It is a graph of slope stability coefficient and contribution ratio of each site provided by an embodiment of the present invention.

[0077] Figure 6 3 is a diagram showing the influence of soil cohesion on slope stability provided by an embodiment of the present invention.

[0078] Figure 7 It is a calculation result diagram of the influence of soil moisture content on slope stability provided by an embodiment of the present invention.

[0079] Figure 8 It is a graph showing the contribution ratio of each part of the slope stability coefficient to the soil moisture content provided by an embodiment of the present invention.

[0080] Fig. 9 This is a diagram showing the influence of vegetation roots on slope stability provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0081] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with implementation cases. 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.

[0082] like Figure 1 As shown, a method for analyzing the characteristics of urban slope stability based on the risk of block sliding provided by an embodiment of the present invention comprises the following steps:

[0083] S101, by measuring slope dimensions, soil and vegetation property data, the stability characteristics of each site are calculated based on the plane sliding method;

[0084] S102, analyzing the relationship between the stability coefficient and each sensitive factor.

[0085] The urban slope stability characteristic analysis method based on block sliding risk provided by the embodiment of the present invention first measures the size, soil and vegetation characteristic data of the slope. The measurement process includes the accurate collection of factors such as the height, slope, soil type, density, water content and vegetation coverage of the slope. These data provide a basis for subsequent stability calculations, making the calculation results more accurate and reliable.

[0086] Next, the stability characteristics of each site were calculated based on the plane sliding method. The plane sliding method is a classic slope stability analysis method that calculates the stability coefficient by assuming that the potential sliding surface is a plane and considering the forces acting on the sliding body, including gravity, shear force, and water pressure. This coefficient is used to judge the safety of the slope. If the coefficient is lower than a certain critical value, it means that the slope is at risk of sliding.

[0087] After obtaining the stability characteristics of each site, the relationship between the stability coefficient and each sensitive factor is further analyzed. Sensitive factors usually include soil type, water content, vegetation coverage, etc. Through statistical analysis and regression analysis, the influence of each sensitive factor on the stability coefficient is explored to determine which factors have the greatest impact on slope stability, thereby providing guidance for slope management and maintenance.

[0088] Finally, based on the above analysis results, targeted slope management measures are proposed. For example, for slopes with high water content and low vegetation coverage, it is recommended to add drainage facilities and vegetation restoration to improve the stability of the slope. Through this analysis method, the stability of urban slopes can be effectively evaluated, potential landslide disasters can be prevented, and the safety of urban infrastructure can be guaranteed.

[0089] The method for measuring slope dimensions, soil and vegetation characteristic data provided by the embodiment of the present invention is as follows:

[0090] For each slope, the main sampling or measurement indicators include: geometric dimensions of the slope, soil properties and vegetation characteristics data;

[0091] The geometric dimensions of the slope are directly measured on site; the soil moisture content is measured using a tensiometer method, and the measured pore water pressure is converted using a theoretical formula to obtain the mass moisture content of the soil;

[0092] The soil type ratio and the volume ratio of vegetation roots in the soil were estimated by field sampling and laboratory screening. The dominant vegetation ratio was estimated by field plot survey, i.e., a representative 1m 2 Sample plots were taken and the growth area proportion of different types of vegetation was determined.

[0093] The method for calculating the stability characteristics of each site based on the plane sliding method provided in the embodiment of the present invention is as follows:

[0094] The plane sliding method is mainly used to analyze the stability characteristics of different types of soil or gravel along an approximately plane sliding surface; its stability coefficient Fs can be expressed as the ratio between the shear strength R of the potential landslide body and the sliding force T under gravity, that is,

[0095]

[0096] Wherein, c represents the effective cohesion coefficient of soil, in kPa, which is estimated in the model according to the effective cohesion of different types of soil and the proportion of soil types at the field survey points; L represents the length of the sliding surface, in m; W represents the weight of the landslide, in kN, which is calculated by the length L and height H of the potential landslide body, including the soil and interstitial water of the landslide body; α represents the angle between the sliding surface L and the horizontal plane, in radians; Pwp represents the pore water pressure on the sliding surface, in kPa, which is related to the water content m of the soil; γ represents the effective internal friction angle of soil, in radians, and the calculation method is similar to the effective cohesion, that is, it is estimated according to the effective internal friction angle of different types of soil and the proportion of soil types at the field survey points; cr represents the root enhancement coefficient, that is, considering the contribution of vegetation roots to slope stability, and its calculation method refers to Stokes as follows,

[0097]

[0098] Where RAR represents the root volume ratio, dimensionless; It represents the root growth angle relative to the sliding surface, in radians. In this paper, it is assumed that the average root growth angle is vertically downward. T r It represents the root damage strength, in kPa. The calculation method is to first determine the proportion of the first three dominant vegetation types at the sampling point, RV, and then use the tensile test to measure the root damage strength TrV of each dominant vegetation type, that is, the ratio of the maximum tensile force that the root system can withstand to the root diameter. Finally, the area ratio coefficient AR of the vegetation is considered, that is,

[0099] T r =AR·∑RV·TrV#(3)

[0100] According to the above calculation method, the stability coefficient can actually be divided into three parts, namely

[0101] Fs=Fs c +Fs w +Fs t #(4)

[0102] in represents the contribution of soil cohesion to stability, represents the contribution of the slope's deadweight to stability, Represents the contribution of vegetation cover and root system to stability.

[0103] like Figure 2 As shown, an urban slope stability characteristic analysis system based on block sliding risk provided by an embodiment of the present invention includes:

[0104] The measurement module is used to calculate the stability characteristics of each site based on the plane sliding method by measuring slope dimensions, soil and vegetation characteristics data;

[0105] The analysis module is used to analyze the relationship between the stability coefficient and each sensitive factor.

[0106] Another object of the present invention is to provide a computer device, which includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the urban slope stability characteristic analysis method based on the risk of block sliding.

[0107] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, enables the processor to execute the steps of the urban slope stability characteristic analysis method based on block sliding risk.

[0108] Another object of the present invention is to provide an information data processing terminal, which is used to implement the urban slope stability characteristic analysis system based on block sliding risk.

[0109] The present invention is specifically implemented:

[0110] 1. This paper selects multiple slopes after land excavation in urban construction in Chongqing as research objects, adopts the plane sliding method considering the deadweight of the landslide body and the root enhancement coefficient, analyzes and calculates the stability of each slope, evaluates the stability of each slope, and discusses the potential impact of factors such as soil characteristics, rainfall, and vegetation on the stability of the landslide body. The research results of the paper can provide technical support for the geological safety and ecological protection of slopes after urban construction excavation.

[0111] 2 Overview of the study area

[0112] Chongqing is located in the transition zone between the Qinghai-Tibet Plateau and the eastern plain of the Yangtze River, specifically in the hilly area on the eastern edge of the Sichuan Basin. The main urban area of ​​Chongqing is a typical mountain city, mainly located on the southern edge of Dabashi, connected to Zhongliang Mountain in the west and Nanshan Mountain in the east, with the main stream of the Yangtze River and the tributaries of the Jialing River passing through. The strata of Chongqing are mainly sandstone and mudstone. Under the influence of the rainy summer caused by the tropical monsoon climate, landslides, bank collapses and other geological disasters frequently occur in Chongqing.

[0113] 2.1 Data Source This paper takes the main urban area of ​​Chongqing as an example, and selects 11 typical slopes in 8 main urban areas such as Yuzhong District and Jiangbei District for measurement according to the actual situation during the sampling period to evaluate their stability characteristics. The location of each slope is shown in Figure 3As shown in Figure 1, for each slope, the main sampling or measurement indicators include: geometric dimensions of the slope, soil properties and vegetation characteristics. The locations of each measuring point and the main measurement data are shown in Table 1. The geometric dimensions of the slope are directly measured on site; the soil moisture content is measured using the tensiometer method (TEROS21), and the measured pore water pressure is converted into the mass moisture content of the soil through a theoretical formula

[23] ; the soil type ratio and the volume ratio of vegetation roots in the soil are estimated by field sampling and laboratory screening methods; the dominant vegetation ratio is measured by the field plot survey method, that is, a representative 1m2 plot is selected, and then the growth area ratio of different types of vegetation is measured.

[0114] Table 1 Basic information and main measurement data of each sampling point

[0115]

[0116]

[0117] 2.2 Research Methods The high and steep slopes formed by the accumulation of soil and gravel after urban construction excavation often have safety risks due to the presence of sliding planes. The plane sliding method is mainly used to analyze the stability characteristics of different types of soil or gravel along the approximately plane sliding surface. Its stability coefficient (Fs) can be expressed as the ratio between the shear strength (R) of the potential landslide body and the sliding force (T) under the action of gravity, that is,

[0118]

[0119] Wherein, c represents the effective cohesion coefficient of soil, in kPa, which is estimated in the model according to the effective cohesion of different types of soil and the proportion of soil types at the field survey points; L represents the length of the sliding surface, in m; W represents the weight of the landslide, in kN, which is calculated by the length (L) and height (H) of the potential landslide body, including the soil and interstitial water of the landslide body; α represents the angle between the sliding surface L and the horizontal plane, in radians; Pwp represents the pore water pressure on the sliding surface, in kPa, which is related to the water content m of the soil, and its calculation method is determined according to the research results of Sasahara Katsuo; γ represents the effective internal friction angle of soil, in radians, and its calculation method is similar to that of effective cohesion, that is, it is estimated according to the effective internal friction angle of different types of soil and the proportion of soil types at the field survey points; cr represents the root enhancement coefficient, that is, considering the contribution of vegetation roots to slope stability, and its calculation method refers to Stokes et al. as follows,

[0120] cr=T r ·RAR·cos 2 φ#(2)

[0121] In the formula, RAR represents the root system volume ratio, which is dimensionless; φ represents the angle of the root system growth relative to the sliding surface, with the unit of radian. In this paper, it is assumed that the average growth angle of the root system is vertically downward, so T r represents the root system failure strength, with the unit of kPa. The calculation method is as follows: First, determine the proportion (RV) of the top three dominant vegetation types at the sampling point, then measure the root system failure strength (TrV) of each dominant vegetation type through a tensile test, that is, the ratio of the maximum tensile force that the root system can withstand to the root diameter. Finally, consider the area proportion coefficient (AR) of the vegetation, that is

[0122] T r =AR·∑RV·TrV#(3)

[0123] According to the above calculation method, the stability coefficient can actually be split into three parts, that is

[0124] Fs=Fs c +Fs w +Fs t #(4)

[0125] Among them represents the contribution of soil cohesion to stability, represents the contribution of the self-weight of the slope body to stability, represents the contribution of vegetation cover and root systems to stability. Using Figure 4 the measured data of multiple sampling points in Chongqing City, the calculation results of the stability coefficient of each slope and the sensitivity factor analysis are as follows.

[0126] 3 Research Results

[0127] 3.1 Analysis of the slope stability characteristics of each sampling point According to the sampling results of typical slopes in each main urban area of Chongqing City, based on the above planar sliding method, the stability coefficient (Fs) values of each slope are calculated. According to the situation, when Fs > 1.0, it indicates that the slope has no landslide risk; when 0.75 < Fs < 1.0, it indicates that it is in a low-risk state; when 0.50 < Fs < 0.75, it indicates that it is in a medium-risk state; when Fs < 0.5, it indicates that it is in a high-risk state. Regarding the calculation results of the stability coefficient of each typical slope in Chongqing City currently ( Figure 5), only the slope stability coefficient (Fs = 0.95) of Banan No. 1 is slightly less than 1, which is in a low-risk state. The stability coefficients of the other slopes are all greater than 1, and there is no landslide risk. The reasons for the low slope stability coefficient of Banan No. 1 site are mainly as follows. First and foremost, the slope is high, which makes the slope steeper. Among all the sampling points, the angle between the sliding surface and the horizontal plane of this site is the largest, so the risk of landslide under the action of its own weight is relatively high. Secondly, the vegetation coverage rate and root volume ratio on the slope are relatively low, only better than the sample point in Yuzhong District. However, the slope inclination angle of the sample point in Yuzhong District is relatively gentle, and the stability coefficient is still relatively high (Fs = 2.09). Generally speaking, the probability of landslide at Banan No. 1 site is still small.

[0128] Further analysis of the contribution of soil cohesion (Fs_c), slope deadweight (Fs_w) and vegetation root system (Fs_t) to the stability coefficient of each site showed the following results: Figure 5 As shown in Figure b, at most sites, soil cohesion and slope deadweight have the most important influence on slope stability, and the contribution at the Yuzhong District site even reaches 99.8%. However, at the sites of Yubei 2, Nan'an, Shapingba, Jiulongpo, and Dadukou where vegetation growth is relatively dense, due to the high vegetation coverage and high root system proportion, the contribution to the slope stability coefficient is also large, and the slope stability coefficients at these sites are all relatively high.

[0129] 3.2 Characteristics of soil cohesion on slope stability Soil cohesion is the cohesive force between soil particles, which comes from the chemical bond force, adsorption force and electromagnetic force between soil particles. Soil with high cohesion has strong shear strength, which helps to prevent soil sliding and improve the stability of the slope. Soil cohesion is mainly affected by soil type and water content. Figure 5 It can be seen from the content that soil cohesion has a crucial impact on slope stability. In this model, we only increase or decrease soil cohesion by about 10% to 20%, and the stability coefficient of the slope will change significantly. The model calculation results are as follows: Figure 6 When the soil cohesion coefficient increases by 20%, its stability coefficient can be increased by 31.2% at most and 13.5% at least compared with a 20% decrease. The key influencing factor is the contribution ratio of soil cohesion to the overall stability coefficient (Fs_c / Fs). Figure 5 , the Fs_c / Fs value of the Yuzhong site can reach about 68%, so its improvement value is relatively high, on the contrary, the Fs_c / Fs value of the Yubei 2 site is only about 29%. In addition, at the Banan 1 site, if the soil cohesion can be increased by 10%, its overall stability coefficient Fs value can reach 1.05, that is, crossing the landslide risk line.

[0130] Regarding how to improve soil cohesion, we can mainly consider two aspects: soil water content and soil itself. Studies have shown that maintaining soil water content within a certain appropriate range (the specific value is related to soil type) can enhance its cohesion characteristics. In addition, from an engineering perspective, physical and chemical methods can be used to improve soil properties. Common methods include adding wire mesh or directly concrete it. The more appropriate one is vegetation concrete technology, which can improve soil properties on the one hand and allow vegetation to grow on the other hand to maintain landscape and ecological needs.

[0131] 3.3 Characteristics of the influence of soil moisture on slope stability Soil moisture directly affects the physical properties of soil, such as density, pore water pressure and shear strength, and therefore has an important impact on slope stability. Generally speaking, the soil moisture content in the field varies between 5% and 60%, so this paper selects this range to discuss the characteristics of the influence of soil moisture on slope stability. The diamond solid point in the figure represents the actual moisture content of the measuring point and its corresponding stability coefficient. The results are shown in Figure 7 As shown. Generally speaking, higher soil moisture content usually shows lower shear strength, which is prone to soil sliding, thereby reducing the stability of the slope. This can also be reflected in the calculation results of the model in this paper. From the calculation results of the calculation model used this time, the stability coefficients of various slopes continue to decrease with the increase of soil moisture content. There are mainly the following reasons. First, in soils with high moisture content, the soil voids will be filled with water, which will increase the weight of the soil itself on the one hand, and increase the weight of the soil itself on the other hand. Both will lead to a decrease in the slope stability coefficient. In addition, the increase in soil moisture content will also affect soil cohesion, but the effect on slope stability is nonlinear. Both low and excessively high soil moisture content will reduce slope stability.

[0132] From the perspective of the contribution of each part of the stability coefficient to the change characteristics of the later period of soil moisture increase, the contribution of water content to reducing the slope stability coefficient by reducing soil cohesion (Fs_c) is the largest, accounting for more than 72% of all influencing factors ( Figure 8 a), the range of Fs_c value itself decreasing with the increase of water content is also the largest, which can reach about 60%. Relatively speaking, the effect of water content on soil deadweight is relatively small, accounting for about 3.5% in total, and its own range of change is only about 4%. Water content cannot affect the stability of the slope through the soil root system, but from the model formula (1), it is mainly due to the increase of water content, which leads to the increase of soil weight itself and the decrease of its stability coefficient.

[0133] From the above analysis, it can be seen that the influence of soil moisture content on the slope stability coefficient is quite significant. For the Banan No. 1 measuring point, under extremely low moisture content, its slope stability coefficient can be increased to above 1.0, reaching a risk-free state. When the current moisture content exceeds 57%, its stability coefficient will be reduced to below 0.75, reaching a medium-risk state, and safety protection measures need to be taken. The natural factor affecting soil moisture content is rainfall. Chongqing is located in the mid-subtropical monsoon climate zone. The annual rainfall in the city is about 1002-1666mm, of which the rainfall in the flood season from May to October can account for more than 70%. This is also one of the important reasons for the large number of landslides and other geological disasters in this mountainous city during the flood season. According to statistics by Xie Yangyi and others, landslides directly caused by heavy rainfall in Chongqing account for about 97.2% of the total landslides.

[0134] 3.4 Characteristics of the influence of vegetation roots on slope stability Vegetation roots mainly improve slope stability by enhancing soil shear strength and reducing soil erosion. The root system directly reinforces the soil structure through physical action, increases the friction between soil particles, and thus improves the overall stability of the soil

[31] . In the sampling sites, the root volume ratio in the soil was basically between 0.01% and 10%. The results of the sensitivity analysis of slope stability to the root system showed that as the density of soil roots increased, the slope stability also increased, but the relationship between the two was not significant. Taking the Yuzhong District site as an example, when the root volume density increased from 0.03% to 10%, the stability coefficient only increased from 2.1 to 4.7. However, this model only considers the influence of the root system on improving the tensile capacity of the soil. In fact, the root system can also affect the stability of the slope in other ways, which is not considered in this model. For example, the root system can increase the porosity of the soil, improve the infiltration and drainage conditions of water, thereby reducing the saturation of the soil and reducing the probability of landslides. The transpiration of vegetation helps reduce soil moisture content, further improving slope stability. In addition, high root density can also reflect high vegetation coverage from another perspective, which can reduce water permeability during heavy rains and prevent landslides. Fig. 9 .

[0135] 3.5 Thoughts on improving slope stability According to the above research conclusions of the present invention, although the slope stability coefficients of all sampling points are relatively high, and only one measuring point has a stability coefficient slightly less than 1, landslides still occur from time to time in Chongqing and even in my country. Based on the calculation results of the present invention and the sensitivity analysis results of various parameters, we propose thoughts on improving the slope stability coefficient.

[0136] 3.5.1 First of all, in terms of engineering measures, soil can be reinforced through support structures and drainage systems. For example, retaining walls, anchors, soil nail walls and other support structures can be used to provide additional anti-slip force to prevent soil sliding. An effective drainage system can lower the groundwater level and reduce the saturation of the soil, thereby improving the stability of the slope. Common drainage measures include setting up drainage pipes, blind ditches, seepage wells, etc. The vegetation concrete technology that has emerged in recent years can significantly enhance soil cohesion while causing minimal interference to vegetation growth. It is one of the important ways to improve the slope stability coefficient.

[0137] 3.5.2 Secondly, increasing vegetation coverage can effectively reduce the velocity of surface water flow and reduce erosion. The root system of plants can enhance the shear strength of soil, especially deep-rooted plants. For slopes in different regions, select appropriate plant species to ensure that plants can grow well in the slope environment.

[0138] 3.5.3 For important slopes, regular monitoring and maintenance should be implemented, including the installation of inclinometers, rain gauges, groundwater level meters and other equipment to regularly monitor slope deformation, rainfall and groundwater level, so as to promptly detect potential stability problems. At the same time, development and construction activities near the slopes should be restricted, and excavation, filling, construction and other activities above or near the slopes should be reduced to avoid increasing the slope load or damaging the original geological structure.

[0139] 4 Conclusion

[0140] Based on the slope characteristic data of multiple stations in the main urban area of ​​Chongqing, the present invention uses the plane sliding method to calculate the stability characteristics of each slope, and analyzes the relationship between slope stability and sensitive factors such as soil cohesion, soil moisture content, and vegetation root characteristics. The paper reaches the following conclusions.

[0141] (1) The slope stability coefficients of all sampling points are basically above 1.0, indicating that the landslide risk is extremely small;

[0142] (2) Soil cohesion contributes the most to maintaining slope stability. When the soil cohesion coefficient increases by 20%, its stability coefficient can be increased by up to 31.2%;

[0143] (3) Soil moisture content increases soil deadweight and reduces soil cohesion, and is therefore negatively correlated with the slope stability coefficient;

[0144] (4) Soil root density can improve the overall stability of the slope by enhancing the soil's shear strength and reducing soil erosion.

[0145] The specific application fields of the present invention mainly include:

[0146] (1) Civil Engineering: In civil engineering projects such as roads, railways, bridges and tunnels, the present invention can be used for stability assessment during slope design and construction stages, helping engineers develop safer and more reliable design solutions.

[0147] (2) Geological disaster prevention and control: The present invention can be applied to areas prone to geological disasters such as landslides and mud-rock flows to monitor slope stability and provide early warnings, thereby improving disaster prevention and emergency response capabilities and reducing casualties and property losses.

[0148] (3) Water conservancy projects: In water conservancy projects such as reservoirs, dams, and riverbanks, the present invention can be used to evaluate the stability of slopes and dam bodies to ensure the long-term safety and stability of the engineering structures.

[0149] (4) Urban planning and construction: In the planning of urban expansion and new construction areas, the present invention can be used to evaluate the stability of different plots of land, provide a scientific basis for the site selection and foundation design of buildings, and reduce safety hazards caused by geological instability.

[0150] (5) Mining and reclamation: In mining activities, the present invention can be used to evaluate the stability of slopes generated during the mining process and to ensure slope safety during land reclamation and environmental restoration after mine closure.

[0151] (6) Agriculture and forestry management: In the management of agricultural terraces, orchards and woodlands, the present invention can be used to assess the risks of soil erosion and slope instability, and help formulate reasonable soil conservation and vegetation management strategies.

[0152] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated design hardware. It can be understood by a person of ordinary skill in the art that the above-mentioned devices and methods can be implemented using computer executable instructions and / or contained in a processor control code, such as a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. Such code is provided on the carrier medium. The device and its modules of the present invention can be implemented by hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, and can also be implemented by a combination of the above-mentioned hardware circuits and software, such as firmware.

[0153] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A method for analyzing the characteristics of urban slope stability based on the risk of block sliding, characterized in that: The following steps are involved: Step 1, by measuring the slope dimensions, soil and vegetation characteristics data, the stability characteristics of each site are calculated based on the plane sliding method; Step 2: Analyze the relationship between the stability coefficient and each sensitive factor.

2. The urban slope stability characteristic analysis method based on block sliding risk according to claim 1 is characterized in that: The method for measuring slope dimensions, soil and vegetation characteristics data is as follows: For each slope, the main sampling or measurement indicators include: slope geometry, soil properties and vegetation characteristics data; The geometric dimensions of the slope are directly measured on site; the soil moisture content is measured using a tensiometer method, and the measured pore water pressure is converted using a theoretical formula to obtain the mass moisture content of the soil; The soil type ratio and the volume ratio of vegetation roots in the soil were estimated by field sampling and laboratory screening. The dominant vegetation ratio was estimated by field plot survey, i.e., a representative 1m 2 Sample plots were taken and the growth area proportion of different types of vegetation was determined.

3. The urban slope stability characteristic analysis method based on block sliding risk according to claim 1 is characterized in that: The method for calculating the stability characteristics of each site based on the plane sliding method is as follows: The plane sliding method is mainly used to analyze the stability characteristics of different types of soil or sand and gravel along an approximately plane sliding surface; Its stability coefficient Fs can be expressed as the ratio between the shear strength R of the potential landslide body and the sliding force T under gravity, that is, Wherein, c represents the effective cohesion coefficient of soil, in kPa, which is estimated in the model according to the effective cohesion of different types of soil and the proportion of soil types at the field survey points; L represents the length of the sliding surface, in m; W represents the weight of the landslide, in kN, which is calculated by the length L and height H of the potential landslide body, including the soil and interstitial water of the landslide body; α represents the angle between the sliding surface L and the horizontal plane, in radians; Pwp represents the pore water pressure on the sliding surface, in kPa, which is related to the water content m of the soil; γ represents the effective internal friction angle of soil, in radians, and the calculation method is similar to the effective cohesion, that is, it is estimated according to the effective internal friction angle of different types of soil and the proportion of soil types at the field survey points; cr represents the root enhancement coefficient, that is, considering the contribution of vegetation roots to slope stability, and its calculation method refers to Stokes as follows, Where RAR represents the root volume ratio, dimensionless; It represents the root growth angle relative to the sliding surface, in radians. In this paper, it is assumed that the average root growth angle is vertically downward. T r It represents the root damage strength, in kPa. The calculation method is to first determine the proportion of the first three dominant vegetation types at the sampling point, RV, and then use the tensile test to measure the root damage strength TrV of each dominant vegetation type, that is, the ratio of the maximum tensile force that the root system can withstand to the root diameter. Finally, the area ratio coefficient AR of the vegetation is considered, that is, T r =AR·∑RV·TrV#(3) According to the above calculation method, the stability coefficient can actually be divided into three parts, namely Fs=Fs c +Fs w +Fs t #(4) in represents the contribution of soil cohesion to stability, represents the contribution of the slope's deadweight to stability, Represents the contribution of vegetation cover and root system to stability.

4. An urban slope stability analysis system based on block sliding risk based on the method of claim 1, characterized in that: The system includes: Data collection module, used to collect slope geometry, soil characteristics and vegetation characteristics data, including soil moisture content, soil type, vegetation root volume ratio and dominant vegetation ratio; The calculation module calculates the stability coefficient of the slope based on the plane sliding method and determines the contribution of soil cohesion, slope deadweight, vegetation root system, etc. to stability; The analysis module is used to analyze the relationship between the slope stability coefficient and various sensitive factors and predict the potential landslide risk of the slope.

5. An urban slope stability measurement device based on the method of claim 1, characterized in that: include: Tensiometer sensor, used to measure the pore water pressure in the slope soil and convert it into soil mass water content through theoretical formula; Sampling equipment for collecting soil samples and vegetation root samples and determining soil type ratios and vegetation root volume ratios; The data processing module performs real-time analysis on the measurement data and provides real-time assessment of slope stability and landslide risk.

6. A device for predicting the risk of landslide of urban slopes based on the method of claim 1, characterized in that: The device comprises: Slope geometry measurement module, used to determine the length, height and slope of the slope; Soil and vegetation characteristics detection module, used to analyze soil cohesion coefficient, internal friction angle and vegetation root enhancement coefficient; The landslide stability calculation module uses the plane sliding method to calculate the stability coefficient of the slope based on the measured data, and outputs the stability analysis results for landslide risk prediction.

7. A system for analyzing characteristics of urban slope stability based on block sliding risk, which implements the method for analyzing characteristics of urban slope stability based on block sliding risk as claimed in any one of claims 1 to 3, characterized in that: The urban slope stability characteristic analysis system based on block sliding risk includes: The measurement module is used to calculate the stability characteristics of each site based on the plane sliding method by measuring slope dimensions, soil and vegetation characteristics data; The analysis module is used to analyze the relationship between the stability coefficient and each sensitive factor.

8. A computer device, characterized in that: The computer device includes a memory and a processor, the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the urban slope stability characteristic analysis method based on block sliding risk as described in any one of claims 1-3.

9. A computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the steps of the method for analyzing the stability characteristics of urban slopes based on the risk of block sliding as described in any one of claims 1 to 3.

10. An information data processing terminal, characterized in that: The information data processing terminal is used to implement the urban slope stability characteristic analysis system based on block sliding risk as described in claim 7.

Images