Safety risk evaluation method for granite residual soil in-service slope

Abstract

The invention discloses a safety risk evaluation method for a granite residual soil in-service slope, and relates to the technical field of safety evaluation. Comprising the following steps: determining safety evaluation indexes and assignments of the granite residual soil slope; acquiring granite residual soil slope sample information; according to the obtained granite residual soil side slope sample information, side slope safety risk preliminary evaluation and preliminary screening are carried out, and a risk side slope is obtained; according to the risk slope stability degree and the accident severity degree, the slope safety risk and the stability level are evaluated; constructing a side slope model by using the side slope parameters, and performing stability targeted analysis and evaluation on the side slope with the instability risk; according to the slope stability evaluation result, a corresponding safety protection strategy is adopted, and safety control over the risky slope is carried out; and carrying out targeted monitoring on the risk slope, and verifying the reliability of the safety evaluation method. According to the invention, the safety condition of the slope can be evaluated more comprehensively.

Description

Technical Field

[0001] The invention relates to the technical field of safety assessment, and more particularly to a safety risk assessment method for an in-service slope of granite residual soil. Background Art

[0002] Granite is widely distributed in my country. Under the long-term physical and chemical effects, after the weathering of granite, a lot of debris will be left in the original place, which is thick and mainly clay minerals, that is, granite residual soil. With the construction of highways in granite areas, a large number of granite residual soil slopes are formed by excavation. The safety and stability of granite residual soil slopes are related to the normal operation of highways.

[0003] Granite residual soil is a special rock engineering material with complex and changeable physical and mechanical properties, which is significantly affected by rainfall, groundwater, slope morphology and other factors. Landslides and collapses of granite residual soil slopes can block traffic and endanger the lives and property of drivers. Systematic analysis and evaluation to ensure the stability and safety of slopes is the guarantee for highway construction and safe operation.

[0004] Therefore, it is an urgent problem for those skilled in the art to propose a safety risk assessment method for in-service granite residual soil slopes to solve the difficulties existing in the prior art. Summary of the invention

[0005] In view of this, the present invention provides a safety risk assessment method for an in-service slope of granite residual soil, which is used to solve the problems existing in the prior art.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A safety risk assessment method for an in-service granite residual soil slope comprises the following steps:

[0008] Determine safety evaluation indicators and assign values: Determine safety evaluation indicators and assign values ​​for granite residual soil slopes based on factors affecting slope stability, combined with the engineering properties of granite residual soil and slope characteristics;

[0009] Obtain slope information: Obtain granite residual soil slope sample information through survey and design data, and build a granite residual soil slope sample information database;

[0010] Obtain slope parameters: collect slope parameters of granite residual soil slopes with instability risks through the granite residual soil slope sample information database;

[0011] Initial safety screening of risky slopes: Based on the acquired slope parameters, initial safety risk assessment and screening are performed to obtain risky slopes;

[0012] Safety assessment of risky slopes: Determine the safety risk coefficient based on the obtained risky slope stability and accident severity, evaluate the slope safety risk, and classify the slope stability level;

[0013] Targeted analysis and evaluation of risk slope stability: The slope model is constructed using the slope parameters of the granite residual soil slope with instability risk. The nonlinear static targeted analysis of the slope model is carried out using the FLAC3D strength reduction method to obtain the slope stability coefficient and conduct slope safety evaluation.

[0014] Safety control of risky slopes: Based on the results of slope safety assessment, take corresponding safety protection measures to control the safety of risky slopes;

[0015] Targeted safety verification of risky slopes: Manual or automated monitoring and follow-up inspections are conducted on the controlled risky slopes to verify the reliability of the safety risk assessment method.

[0016] The above method optionally includes the following specific contents for constructing a granite residual soil slope sample information database:

[0017] Combined with the hierarchical database construction method, a database of granite residual soil slopes is established, and based on the survey and design data, a sample information database of granite residual soil slopes along the highway is formed.

[0018] In the above method, optionally, the specific contents of the slope parameters of the granite residual soil slope with instability risk collected through the granite residual soil slope sample information database are:

[0019] The variable query method is used to find the parameter table of slopes with instability risk in the granite residual soil slope sample information database;

[0020] The slope parameters of the granite residual soil slope found in the slope parameter table are: slope height, slope length, slope level, height of each slope level, platform width, cohesion, internal friction angle, dry density, water content, and permeability coefficient.

[0021] The above method is optional, and the specific contents of assessing slope safety risks and classifying slope stability levels are as follows:

[0022] Obtain slope safety risk scores based on risk slope stability and the severity of accidents;

[0023] Based on the safety risk score, the safety risk of the granite residual soil slope is estimated and the stability grade is divided.

[0024] The above method can optionally use the slope parameters of the granite residual soil slope with instability risk to construct the slope model. The specific content is:

[0025] The slope parameters of the granite residual soil slope with the risk of instability were imported into the Rhinocerse 3D modeling software to construct the slope model.

[0026] The above method is optional. The specific contents of using FLAC3D strength reduction method to perform nonlinear static targeted analysis on the slope model are as follows:

[0027] By adjusting the cohesion and internal friction angle of the granite residual soil slope, the gradual process of the granite residual soil slope from stability to instability is simulated until the granite residual soil slope reaches a critical instability state. In this process, the analysis results are obtained by recording the stress distribution and displacement change characteristics inside the granite residual soil slope.

[0028] The above method can optionally include the following specific contents of slope safety assessment through slope stability coefficient:

[0029] Granite residual soil slope with Fs≥1.30 is a stable slope;

[0030] 1.30>Fs≥1.08 granite residual soil slope is basically stable slope;

[0031] 1.08>Fs≥1.00 The granite residual soil slope is an unstable slope;

[0032] The granite residual soil slope with 1.00<Fs is an unstable slope.

[0033] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a method for safety risk assessment of in-service slopes of granite residual soil, which has the following beneficial effects:

[0034] 1) It retains the advantage of simple calculation of limit equilibrium theory and solves the problem that the slope stability evaluation method in the existing technology cannot take into account both simple calculation and high simulation accuracy;

[0035] 2) It can remind operation and maintenance personnel to handle the problem in time, take targeted measures, avoid blind operation, and reduce economic costs when completing operation and maintenance;

[0036] 3) Combining the results obtained by the limit equilibrium method and the strength reduction method, a comprehensive evaluation is made on the safety of the granite residual soil slope. The present invention can more comprehensively evaluate the safety status of the slope and provide a strong guarantee for the stability of the granite residual soil slope. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0038] Figure 1 A flow chart of a safety risk assessment method for an in-service slope of granite residual soil provided by the present invention;

[0039] Figure 2 Installation diagram of a granite residual soil slope displacement meter provided by an embodiment of the present invention;

[0040] Figure 3 Installation diagram of anchor stress meter for granite residual soil slope provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] See also Figure 1 As shown, the present invention discloses a safety risk assessment method for an in-service slope of granite residual soil, comprising the following steps:

[0043] Determine safety evaluation indicators and assign values: Determine safety evaluation indicators and assign values ​​for granite residual soil slopes based on factors affecting slope stability, combined with the engineering properties of granite residual soil and slope characteristics;

[0044] Obtain slope information: Obtain granite residual soil slope sample information through survey and design data, and build a granite residual soil slope sample information database;

[0045] Obtain slope parameters: collect slope parameters of granite residual soil slopes with instability risks through the granite residual soil slope sample information database;

[0046] Initial safety screening of risky slopes: Based on the acquired slope parameters, initial safety risk assessment and screening are performed to obtain risky slopes;

[0047] Safety assessment of risky slopes: Determine the safety risk coefficient based on the obtained risky slope stability and accident severity, evaluate the slope safety risk, and classify the slope stability level;

[0048] Targeted analysis and evaluation of risk slope stability: The slope model is constructed using the slope parameters of the granite residual soil slope with instability risk. The nonlinear static targeted analysis of the slope model is carried out using the FLAC3D strength reduction method to obtain the slope stability coefficient and conduct slope safety evaluation.

[0049] Safety control of risky slopes: Based on the results of slope safety assessment, take corresponding safety protection measures to control the safety of risky slopes;

[0050] Targeted safety verification of risky slopes: Manual or automated monitoring and follow-up inspections are conducted on the controlled risky slopes to verify the reliability of the safety risk assessment method.

[0051] Specifically, the specific contents of determining the safety evaluation index and value assignment of granite residual soil slope are as follows:

[0052] According to the factors affecting the stability of granite residual soil slope, the safety assessment of granite residual soil slope is determined as engineering geological conditions, geometric characteristics of slope section, surface water and groundwater conditions, damage conditions of slope and reinforcement, etc.; each assessment index is assigned a value according to the expert evaluation method. The assessment indexes and their values ​​are shown in Table 1.

[0053] Table 1 Safety evaluation index system for granite residual soil slope

[0054]

[0055]

[0056]

[0057] Using Security Risk Score R S Assess the safety risk level of the slope:

[0058] R S =F×T S =F×I S ×C S

[0059] F is the normalization factor, which is 0.21 for granite residual soil slope.

[0060] I S is the stability score, I S =A+B1+B2+C1+C2+D, and take values ​​according to Table 1.

[0061] C S The landslide consequence score is a score calculated by quantitatively evaluating the severity of the consequences of a landslide on the slope. The value is determined according to Table 2.

[0062] Table 2 Landslide consequence score coefficients for granite residual soil slope

[0063]

[0064] Furthermore, the specific contents of constructing the granite residual soil slope sample information database are as follows:

[0065] Combined with the hierarchical database construction method, a database of granite residual soil slopes is established, and based on the survey and design data, a sample information database of granite residual soil slopes along the highway is formed.

[0066] Furthermore, the specific contents of the slope parameters of granite residual soil slopes with instability risk collected through the granite residual soil slope sample information database are as follows:

[0067] The variable query method is used to find the parameter table of slopes with instability risk in the granite residual soil slope sample information database;

[0068] The slope parameters of the granite residual soil slope found in the slope parameter table are: slope height, slope length, slope level, height of each slope level, platform width, cohesion, internal friction angle, dry density, water content, and permeability coefficient.

[0069] Furthermore, the specific contents of assessing slope safety risks and classifying slope stability levels are as follows:

[0070] Obtain slope safety risk scores based on risk slope stability and the severity of accidents;

[0071] Based on the safety risk score, the safety risk of the granite residual soil slope is estimated and the stability grade is divided.

[0072] According to the security risk score R S , assess the safety risk of granite residual soil slope and classify the stability level, see Table 3.

[0073] Table 3 Safety risk assessment table of granite residual soil

[0074] <![CDATA[Safety risk value R S > Security Risk Assessment Stability classification ≤45 Good slope stability I >45，≤60 The slope is partially damaged, but the stability is not affected Ⅱ >45，≤60 The overall condition is average, but there is a risk of local instability. Ⅲ >60 Poor slope stability Ⅳ

[0075] Furthermore, the specific contents of constructing the slope model using the slope parameters of the granite residual soil slope with instability risk are as follows:

[0076] The slope parameters of the granite residual soil slope with the risk of instability were imported into the Rhinocerse 3D modeling software to construct the slope model.

[0077] Furthermore, the specific contents of the nonlinear static targeted analysis of the slope model using the FLAC3D strength reduction method are as follows:

[0078] By adjusting the cohesion and internal friction angle of the granite residual soil slope, the gradual process of the granite residual soil slope from stability to instability is simulated until the granite residual soil slope reaches a critical instability state. In this process, the analysis results are obtained by recording the stress distribution and displacement change characteristics inside the granite residual soil slope.

[0079] Specifically, stress distribution characteristics: The stress distribution of granite residual soil is affected by many factors, including the difference between original soil and remolded soil, the size of confining pressure, and the change of axial strain. The failure deviator stress q and initial stiffness of original soil are usually greater than those of remolded soil, and the failure deviator stress q also increases with the increase of confining pressure. Under the same confining pressure, the failure deviator stress and initial stiffness of original soil are greater than those of remolded soil. In addition, the structural stress sharing ratio η decreases rapidly with the increase of axial strain, and then gradually increases at a slower rate. The minimum peak point appears when the axial strain ε1 = 1% ~ 1.5%, which is the strain value of remolded soil in the yield stage. The initial stiffness of original soil in low stress state is much greater than that of remolded soil, and for the test constant n, the remolded sample is larger than the original sample. The normalized tangent stiffness of original soil under different stress paths gradually decreases with the increase of axial strain, and the initial normalized tangent stiffness under low confining pressure is significantly greater than the initial normalized tangent stiffness 1 under high confining pressure.

[0080] Displacement change characteristics: The displacement change of the granite residual soil slope is affected by many factors, including slope excavation, soil stress path, and soil structure. The Midas GTS simulation results show that the soil on the inner and outer sides of the slope move inward, while the soil rebounds on the side close to the roadbed in the vertical direction. The soil at a certain distance away from the slope undergoes displacement and settlement. After the slope excavation is completed, the stress of the soil decreases overall.

[0081] Specifically, the original shear strength parameters of the slope, cohesion and internal friction angle, are simultaneously reduced by a factor of F to obtain a set of new shear strength parameters, cohesion and internal friction angle. The new shear strength parameters, cohesion and internal friction angle, are then input as new shear strength parameters, and then analyzed and calculated. This reduction is repeated until the limit equilibrium state is reached and shear instability failure occurs. At this time, the corresponding reduction factor is the slope stability factor Fs.

[0082] Furthermore, the specific contents of slope safety evaluation through slope stability coefficient are as follows:

[0083] Granite residual soil slope with Fs≥1.30 is a stable slope;

[0084] 1.30>Fs≥1.08 granite residual soil slope is basically stable slope;

[0085] 1.08>Fs≥1.00 The granite residual soil slope is an unstable slope;

[0086] The granite residual soil slope with 1.00<Fs is an unstable slope.

[0087] Specifically, the classification standard of granite residual soil slope stability coefficient is shown in Table 4.

[0088] Table 4 Classification standard of stability coefficient of granite residual soil slope

[0089]

[0090] In a specific embodiment, a highway ZK96+341.0~ZK96+706.2 was selected as an engineering example for evaluation. The height of the slope of ZK96+341.0~ZK96+706.2 is 30m, and it is a granite residual soil slope. There are four levels in total, and the slope rates are 1:1, 1:1.25, 1:1.25, and 1:1.25 respectively. The first level slope is protected by anchor frame beams, the second and third level slopes are protected by anchor cable frames, and the fourth level slope is protected by spraying grass. There is groundwater seepage in the lower part of the slope, the water output is small, and there are obvious signs of moisture on the slope, which can easily lead to weak interlayers. The surface drainage system is perfect, and there is no runoff and slope water collection on the slope. The slope was excavated and exposed, and no weak interlayer was found.

[0091] The evaluation indexes of granite residual soil slope are A=60, B1=40, B2=40, C1=0, C2=5, D=30, I S =A+B1+B2+C1+C2+D=175; the granite residual soil slope is high and there is a risk of stability, C S The value is 1.25; its security risk score R S =0.21×1.25×175=45.9. The slope is judged to be partially damaged, but it does not affect the stability or the overall condition is general. There is a risk of local instability. It is advisable to conduct targeted stability analysis of the risk slope. The calculated stability coefficient of the granite residual soil slope Fs=1.28. According to regulations, the stability of the granite residual soil slope is a basically stable slope, and daily maintenance and necessary monitoring measures should be strengthened. In order to verify the feasibility and rationality of the protection measures and safety evaluation measures, the displacement and stress of the granite residual soil slope were selected for intelligent monitoring (see Figure 2 and Figure 3 ), and carried out long-term tracking monitoring. The monitoring results showed that the slope displacement and anchor stress curves were stable, and the slope was in a stable state as a whole. This conclusion was consistent with the evaluation results of the safety risk assessment method, which verified the rationality of the safety risk assessment method.

[0092] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0093] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A safety risk assessment method for an in-service granite residual soil slope, characterized in that: The following steps are involved: Determine safety evaluation indicators and assign values: Determine safety evaluation indicators and assign values ​​for granite residual soil slopes based on factors affecting slope stability, combined with the engineering properties of granite residual soil and slope characteristics; Obtain slope information: Obtain granite residual soil slope sample information through survey and design data, and build a granite residual soil slope sample information database; Obtain slope parameters: collect slope parameters of granite residual soil slopes with instability risks through the granite residual soil slope sample information database; Initial safety screening of risky slopes: Based on the acquired slope parameters, initial safety risk assessment and screening are performed to obtain risky slopes; Safety assessment of risky slopes: Determine the safety risk coefficient based on the obtained risky slope stability and accident severity, evaluate the slope safety risk, and classify the slope stability level; Targeted analysis and evaluation of risk slope stability: The slope model is constructed using the slope parameters of the granite residual soil slope with instability risk. The nonlinear static targeted analysis of the slope model is carried out using the FLAC3D strength reduction method to obtain the slope stability coefficient and conduct slope safety evaluation. Safety control of risky slopes: Based on the results of slope safety assessment, take corresponding safety protection measures to control the safety of risky slopes; Targeted safety verification of risky slopes: Manual or automated monitoring and follow-up inspections are conducted on the controlled risky slopes to verify the reliability of the safety risk assessment method.

2. The method for safety risk assessment of an in-service granite residual soil slope according to claim 1 is characterized in that: The specific contents of constructing the granite residual soil slope sample information database are as follows: Combined with the hierarchical database construction method, a database of granite residual soil slopes is established, and based on the survey and design data, a sample information database of granite residual soil slopes along the highway is formed.

3. The method for safety risk assessment of an in-service granite residual soil slope according to claim 1 is characterized in that: The specific contents of the slope parameters of granite residual soil slopes with instability risk collected through the granite residual soil slope sample information database are as follows: The variable query method is used to find the parameter table of slopes with instability risk in the granite residual soil slope sample information database; The slope parameters of the granite residual soil slope found in the slope parameter table are: slope height, slope length, slope level, height of each slope level, platform width, cohesion, internal friction angle, dry density, water content, and permeability coefficient.

4. The method for safety risk assessment of an in-service granite residual soil slope according to claim 1 is characterized in that: The specific contents of assessing slope safety risks and classifying slope stability levels are as follows: Obtain slope safety risk scores based on risk slope stability and the severity of accidents; Based on the safety risk score, the safety risk of the granite residual soil slope is estimated and the stability grade is divided.

5. The method for safety risk assessment of an in-service granite residual soil slope according to claim 1, characterized in that: The specific contents of constructing the slope model using the slope parameters of the granite residual soil slope with instability risk are as follows: The slope parameters of the granite residual soil slope with the risk of instability were imported into the Rhinocerse 3D modeling software to construct the slope model.

6. The method for safety risk assessment of an in-service granite residual soil slope according to claim 1, characterized in that: The specific contents of the nonlinear static targeted analysis of the slope model using the FLAC3D strength reduction method are as follows: By adjusting the cohesion and internal friction angle of the granite residual soil slope, the gradual process of the granite residual soil slope from stability to instability is simulated until the granite residual soil slope reaches a critical instability state. In this process, the analysis results are obtained by recording the stress distribution and displacement change characteristics inside the granite residual soil slope.

7. The method for safety risk assessment of an in-service granite residual soil slope according to claim 1, characterized in that: The specific contents of slope safety evaluation through slope stability coefficient are as follows: Granite residual soil slope with Fs≥1.30 is a stable slope; 1.30>Fs≥1.08 granite residual soil slope is basically stable slope; 1.08>Fs≥1.00 The granite residual soil slope is an unstable slope; The granite residual soil slope with 1.00<Fs is an unstable slope.

Images