Slope stability monitoring and early warning method based on Poisson's ratio loss direction rate

Abstract

The invention relates to the field of slope protection, fixation and prevention, in particular to a slope stability monitoring and early warning method based on Poisson's ratio loss direction rate, comprising the following steps: step 1, determining Poisson's ratio parameters and critical Poisson's ratio; 2, selecting and arranging excavation displacement monitoring points; step 3, recording displacement monitoring data at each monitoring point; 4, determining a vertical displacement direction rate parameter of the monitoring point; 5, dividing a slope plastic region range; and 6, determining a slope damage direction rate critical value by using a basic principle of damage mechanics, and determining the overall stability condition of the slope. The whole steps are few, operation is easy and convenient, and relevant parameters of the slope stability of the to-be-excavated area can be obtained through a small number of physical parameters.

Description

Technical Field

[0001] The invention relates to the field of slope consolidation and prevention, and in particular to a slope stability monitoring and early warning method based on Poisson's ratio loss direction rate. Background Art

[0002] In recent years, with the vigorous promotion of infrastructure, more and more high and steep slopes have been generated, and the problems of high and steep slope excavation and construction in engineering practice are increasing. High and steep slope disasters are characterized by concealment, suddenness, strong destructiveness and difficulty in prevention and control. Due to the influence of comprehensive factors such as slope geometry, soil parameters and differences in geological conditions, the slope stability evaluation of high and steep slopes has not yet met the requirements of engineering construction safety and disaster reduction and prevention.

[0003] At present, the main research methods for slope stability are limit equilibrium method, finite element method, etc. The basic principle of limit equilibrium method is to treat the rock blocks that make up the landslide as rigid bodies, and then use the theoretical mechanics principles to analyze the conditions when the rock mass is in a limit equilibrium state, without considering its deformation and deformation coordination. It is a commonly used method in landslide stability analysis.

[0004] The drawback of this type of method is that it has extremely strict requirements on the boundary conditions of the landslide and the physical and mechanical parameters of the slope, and it is unable to detect the change of slope stability over time, which has limitations. The finite element method can simulate infinite complex bodies with limited and interrelated units, so that complex geometric bodies can be simplified with corresponding units, so as to model and analyze the results and simplify complex engineering problems that seem difficult to solve. However, its accuracy fluctuates greatly, which is affected by the level of modeling, boundary conditions, and whether the simulation of load conditions is realistic.

[0005] Therefore, those skilled in the art are in urgent need of a slope stability prediction method that can solve the problems existing in the current methods for determining slope stability, such as multiple slope physical parameters, large limitations, large amount of calculation, cumbersome steps, and low prediction accuracy. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention aims to provide a slope stability prediction method with wide application range, simple operation steps, small amount of calculation and accurate prediction.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a slope stability monitoring and early warning method based on Poisson's ratio loss direction rate, comprising the following steps:

[0008] Step 1: Determine the Poisson's ratio parameter and critical Poisson's ratio: Drill and sample, and use uniaxial compression test to obtain the lateral strain ε of the original soil and rock during the entire compression test process. y Value and axial strain ε xvalue, determine the variation law of Poisson's ratio of slope materials, and use the Poisson's ratio formula Determine the Poisson's ratio parameter μ0 and the critical Poisson's ratio μ 界 ;

[0009] Step 2: Select and arrange excavation displacement monitoring points: Through actual investigation and measurement, obtain the geometric characteristics and geomorphic information of the slope, determine the slope excavation method, arrange monitoring points for the excavated slope to be measured, and obtain the lateral displacement and vertical displacement of the monitoring point position during the entire construction process;

[0010] Step 3: Record the displacement monitoring data at each monitoring point: According to the construction plan, the displacement response caused by each excavation of the slope is monitored in real time, and the displacement monitoring data transmitted by the displacement monitoring equipment is preprocessed;

[0011] Step 4: Determine the vertical displacement direction rate parameter of the monitoring point: Based on step 3, Calculate the slope k at each monitoring point during the excavation process ij The displacement direction rate at the completion of the mth step of excavation is: is the direction rate when the mth step of excavation is completed after the monitoring points are arranged, is the lateral displacement when the mth step of excavation is completed after the monitoring points are arranged is the vertical displacement when the mth step of excavation is completed after the monitoring points are arranged;

[0012] Step 5: Divide the scope of the slope plastic zone: Conduct instability criterion on the vertical direction rate of the slope monitoring, and determine the scope of the slope plastic zone by establishing the damage direction rate related to the Poisson's ratio and the vertical displacement direction rate;

[0013] Step 6: Use the basic principles of damage mechanics to determine the critical value of the slope damage direction rate and the overall stability of the slope.

[0014] The above-mentioned slope stability monitoring and early warning method based on Poisson's ratio loss direction rate adopts a stratified sampling method to take original samples in the technical hole according to different strata, and the sampling is taken from 1.5 meters below the ground with a sampling interval of 1-3 meters.

[0015] In the above-mentioned slope stability monitoring and early warning method based on Poisson's ratio loss direction rate, step 2 comprises:

[0016] Step 2-1: Determine the number of excavation levels and the excavation height of each level;

[0017] Step 2-2: Set up monitoring points in the direction of the vertical and parallel free surface of each step excavated;

[0018] Step 2-3: Arrange three rows of monitoring points in the horizontal direction, denoted as k ij(i=1,2,…,m;j=1,2,…,m), represents the jth monitoring point in the i-th row;

[0019] Step 2-4: Use displacement monitoring equipment to obtain the lateral and vertical displacements of the monitoring point during the entire construction process.

[0020] In the above slope stability monitoring and early warning method based on Poisson's ratio loss direction rate, step 5 comprises:

[0021] Step 5-1: Set the toe of the slope as θ, set the parallel to the toe of the slope as the X-axis and the perpendicular to the slope as the Y-axis to establish a rectangular coordinate system, where the corresponding axial strain is ε x , the transverse strain is ε y ;

[0022] Step 5-2: Calculate the vertical displacement direction rate according to Then get

[0023] Step 5-3: Substitute the Poisson's ratio parameter μ0 and critical Poisson's ratio μ obtained in step 1 界 , substitute into the formula of step 5-2 to determine the vertical displacement response rate U0 of the slope at the corresponding stage and the critical vertical displacement response rate U 界 ;

[0024] Step 5-4: Determine the displacement change of each monitoring point according to the change of the displacement response rate of each monitoring point, calculate the direction rate of each point and determine the stability of each monitoring point.

[0025] In the above slope stability monitoring and early warning method based on Poisson's ratio loss direction rate, step 5-4 comprises:

[0026] When the displacement response rate of a monitoring point is between U0-U 间 When the range fluctuates, the area where the monitoring point is located is in a stable state;

[0027] When the displacement response rate of a monitoring point is between U0-U 间 When the monitoring point is outside the range or a mutation occurs, there is a potential plastic zone in the area where the monitoring point is located.

[0028] In the above slope stability monitoring and early warning method based on Poisson's ratio loss direction rate, step 6 comprises:

[0029] Step 6-1: Based on the basic principles of damage mechanics, the damage variable D is used to represent the damage process and damage degree. Among them, E t Initial elastic modulus of rock and soil, E0 elastic modulus of rock and soil after damage;

[0030] Step 6-2: When the slope is not damaged, E t =E0, D = 0, when the slope is completely damaged, E t =0, D=1;

[0031] Step 6-3: According to the range of the slope plastic zone divided in step 5, when the layer belongs to the stable zone, it is recorded as A1, and when the layer is the unstable zone, it is recorded as A2. The number of stable zones and unstable zones is counted and recorded as C1, C 2。 When the slope is not damaged, C2=0, D=0; when the slope is completely damaged, C1=0, D=1;

[0032] Step 6-4: Based on the equivalence of the above calculations in evaluating the damage deformation law during foundation pit excavation, define the damage variable of the slope According to the importance level of the slope, refer to the relevant slope engineering specifications to set the slope safety factor K for the slope and determine the critical value of the damage variable of the slope body. D cr The overall stability criterion of the slope is determined by using the safety factor.

[0033] In the above-mentioned slope stability monitoring and early warning method based on Poisson's ratio loss direction rate, step 6 comprises: performing the following analysis and evaluation on the stability of the slope according to the overall stability criterion of the slope.

[0034] The above slope stability monitoring and early warning method based on Poisson's ratio loss direction rate is used when the slope damage variable D<D cr When the slope damage variable D>D cr The slope is in an unstable state as a whole.

[0035] The slope stability monitoring and early warning method based on Poisson's ratio loss directional rate of the present invention has the following beneficial effects: through drilling and stratified sampling, sample analysis can be performed on the pending excavation area more accurately; on the basis of determining the parameter properties of the rock mass Poisson's ratio, the horizontal displacement and vertical displacement of the measuring points in the vertical and horizontal directions of the excavation free surface are monitored, and the vertical displacement directional rate of each monitoring point is calculated; by establishing a damage directional rate related to the Poisson's ratio and the vertical displacement directional rate, the critical value of the slope damage directional rate is determined using the basic principles of damage mechanics, and then the overall stability of the slope is determined; the overall steps are few, the operation is simple, and the relevant parameters of the slope stability of the pending excavation area can be obtained using a small amount of physical parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 A flow chart of a high and steep slope stability monitoring and early warning method based on Poisson's ratio loss direction rate provided by an embodiment of the present invention;

[0038] Figure 2 The lateral strain ε of the original soil and rock during the entire compression test provided by the embodiment of the present invention is y Value and axial strain ε x Value change curve;

[0039] Figure 3 A schematic diagram of high and steep slope excavation and monitoring point arrangement provided by an embodiment of the present invention;

[0040] Figure 4 A schematic diagram of the oblique excavation arrangement of the high and steep slope monitoring points provided by an embodiment of the present invention;

[0041] Figure 5 A schematic diagram of the layout of the front view of the high and steep slope monitoring points provided by the embodiment of the present invention;

[0042] Figure 6 A simplified model of a landslide provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0044] It should be noted that, based on the present disclosure, those skilled in the art should understand that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement a device and / or practice a method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.

[0045] Example 1

[0046] like Figure 1As shown, a slope stability monitoring and early warning method based on Poisson's ratio loss direction rate includes the following steps.

[0047] Step 1: Determine the Poisson's ratio parameters and critical Poisson's ratio: Borehole sampling. Borehole sampling adopts a stratified sampling method to take original samples in the technical hole according to different strata. The sampling is taken from 1.5 meters below the ground, and the sampling interval is 1-3 meters.

[0048] Using uniaxial compression test, the lateral strain ε of the original soil and rock during the whole compression test was obtained. y Value and axial strain ε x value, determine the variation law of Poisson's ratio of slope materials, and use the Poisson's ratio formula Determine the Poisson's ratio parameter μ0 and the critical Poisson's ratio μ 界 .

[0049] Step 2: Select and arrange excavation displacement monitoring points: Through actual investigation and measurement, obtain the geometric characteristics and geomorphological information of the slope, determine the slope excavation method, arrange monitoring points on the excavated slope to be measured, and obtain the lateral and vertical displacements of the monitoring point positions during the entire construction process.

[0050] include:

[0051] Step 2-1: Determine the number of excavation levels and the excavation height of each level.

[0052] Step 2-2: Set up monitoring points on the vertical and parallel free surfaces of each step excavated.

[0053] Step 2-3: Arrange three rows of monitoring points in the horizontal direction, denoted as k ij (i=1,2,…,m;j=1,2,…,m), represents the jth monitoring point in the i-th row.

[0054] Step 2-4: Use displacement monitoring equipment to obtain the lateral and vertical displacements of the monitoring point during the entire construction process.

[0055] Step 3: Record the displacement monitoring data at each monitoring point: According to the construction plan, the displacement response caused by each excavation of the slope is monitored in real time, and the displacement monitoring data transmitted by the displacement monitoring equipment is preprocessed.

[0056] Step 4: Determine the vertical displacement direction rate parameter of the monitoring point: Based on step 3, Calculate the slope k at each monitoring point during the excavation process ij The displacement direction rate at the completion of the mth step of excavation is: is the direction rate when the mth step of excavation is completed after the monitoring points are arranged, is the lateral displacement when the mth step of excavation is completed after the monitoring points are arranged, is the vertical displacement when the mth step of excavation is completed after the monitoring points are arranged

[0057] Step 5: Divide the scope of the slope plastic zone: Conduct instability criterion on the vertical direction rate of the slope monitoring, and determine the scope of the slope plastic zone by establishing the damage direction rate related to the Poisson's ratio and the vertical displacement direction rate.

[0058] include:

[0059] Step 5-1: Set the toe of the slope as θ, set the parallel to the toe of the slope as the X-axis and the perpendicular to the slope as the Y-axis to establish a rectangular coordinate system, where the corresponding axial strain is ε x , the transverse strain is ε y .

[0060] Step 5-2: Calculate the vertical displacement direction rate according to Then get

[0061] Step 5-3: Substitute the Poisson's ratio parameter μ0 and the critical Poisson's ratio μ obtained in step 1 界 , substitute into the formula of step 5-2 to determine the vertical displacement response rate U0 of the slope at the corresponding stage and the critical vertical displacement response rate U 界 .

[0062] Step 5-4: Determine the displacement change of each monitoring point according to the change of the displacement response rate of each monitoring point, calculate the direction rate of each point and determine the stability of each monitoring point.

[0063] Specifically, when the displacement response rate of a monitoring point is between U0-U 间 When the value fluctuates within the interval, the area where the monitoring point is located is in a stable state.

[0064] When the displacement response rate of a monitoring point is between U0-U 间 When the monitoring point is outside the range or a mutation occurs, there is a potential plastic zone in the area where the monitoring point is located.

[0065] Step 6: Use the basic principles of damage mechanics to determine the critical value of the slope damage direction rate and the overall stability of the slope.

[0066] include:

[0067] Step 6-1: Based on the basic principles of damage mechanics, the damage variable D is used to represent the damage process and damage degree. Among them, E t E0 is the initial elastic modulus of rock and soil, and E0 is the elastic modulus of rock and soil after damage.

[0068] Step 6-2: When the slope is not damaged, E t =E0, D = 0, when the slope is completely damaged, Et =0, D=1.

[0069] Step 6-3: According to the range of the slope plastic zone divided in step 5, when the layer belongs to the stable zone, it is recorded as A1, and when the layer is the unstable zone, it is recorded as A2. The number of stable zones and unstable zones is counted and recorded as C1, C 2。 When the slope is not damaged, C2=0, D=0; when the slope is completely damaged, C1=0, D=1.

[0070] Step 6-4: Based on the equivalence of the above calculations in evaluating the damage deformation law during foundation pit excavation, define the damage variable of the slope According to the importance level of the slope, refer to the relevant slope engineering specifications to set the slope safety factor K for the slope and determine the critical value of the damage variable of the slope body. D cr The overall stability criterion of the slope is determined by using the safety factor.

[0071] According to the overall stability criterion of the slope, the stability of the slope is analyzed and evaluated as follows.

[0072] When the slope damage variable D<D cr When the slope damage variable D>D cr The slope is in an unstable state as a whole.

[0073] Example 2

[0074] This embodiment is an embodiment in which specific implementation parameters are substituted. Figure 1 The flowchart of the high and steep slope stability monitoring and early warning method based on Poisson's ratio loss direction rate is shown, and a high and steep slope stability monitoring and early warning method is introduced.

[0075] The high and steep slope stability monitoring and early warning method may include the following steps.

[0076] S1, Poisson's ratio parameter μ and critical Poisson's ratio μ 界 of determination.

[0077] In this embodiment, for the high and steep slope to be excavated, original soil (rock) samples are taken in the technical hole according to different strata. The sampling should be carried out from 1.5m below the ground, with a spacing of 1.5m. Layered sampling is adopted, and strata with a layer thickness greater than 0.5m must be sampled separately. When the soil (rock) properties are complex or the soil (rock) layer thickness is not large, the density can be appropriately increased; when the soil (rock) properties are single or the soil (rock) layer thickness is large, the sampling spacing can also be increased. After sampling, a uniaxial compression test is carried out using instruments such as the YE-600 hydraulic material testing machine, the JN-16 static resistance strain gauge, and the resistance strain gauge (BX-120) to obtain the lateral strain ε of the original soil and rock during the entire compression test.y and axial strain ε x Values, such as Figure 2 As shown. According to the Poisson's ratio formula The Poisson's ratio parameter μ0 in the elastic stage and the Poisson's ratio parameter μ at the critical point between the destruction stage are calculated. 界 .

[0078] For example, the high and steep slope to be excavated is sampled in layers, and the Poisson's ratio μ0 = 0.28 of each rock layer in the elastic stage and the Poisson's ratio parameter μ0 of the critical point between the failure stage are determined by uniaxial compression test. 界 =0.42.

[0079] S2, selection and layout of excavation displacement monitoring points.

[0080] Through actual investigation and measurement, the geometric characteristics and geomorphic information of the slope, that is, the slope foot, are obtained to determine the slope excavation method, excavation level m, and excavation height h of each level. Since the uniaxial compression test studies the mechanical properties and deformation characteristics of the soil by applying pressure perpendicular to the axis of the rock sample, and the direction of the maximum principal stress of the slope is parallel to the slope surface where the slope angle is large, during the multi-level excavation construction of the high and steep slope, monitoring points are arranged in the direction of the vertical and parallel steps obtained by each level of excavation. A total of three rows of monitoring points are arranged in the horizontal direction, and the monitoring points are recorded as k ij (i=1,2,…,m;j=1,2,…,m), represents the jth monitoring point in the i-th row. The displacement monitoring equipment is mainly based on the slope monitoring cloud platform, supplemented by the total station, to obtain the lateral displacement and vertical displacement of the monitoring point position during the entire construction process.

[0081] In this embodiment, the slope foot θ = 30°, the excavation level m = 5, the excavation height of each level h = 4m, and the excavation monitoring diagram is as follows Figure 3 , Figure 4 , Figure 5 shown.

[0082] S3, recording the displacement monitoring data at each monitoring point.

[0083] According to the construction plan, the displacement response caused by each excavation of the slope is monitored in real time. The displacement monitoring data transmitted by the displacement monitoring equipment is preprocessed and the kth excavation at the mth step is recorded. ij The lateral displacement of each monitoring point is The vertical displacement is During this process, monitoring instruments and equipment should be maintained in a timely manner, and fixed personnel should be assigned to monitor and organize data to reduce monitoring errors including horizontal and vertical displacements.

[0084] In this embodiment, the specific monitoring data are shown in Table 1, unit (mm).

[0085] Table 1 Specific test data

[0086]

[0087]

[0088] S4, determination of vertical displacement direction rate parameters of each monitoring point on the slope.

[0089] According to the formula Calculate the slope k at each monitoring point during the excavation process ij Displacement direction rate at the completion of the mth step of excavation.

[0090] in: is the monitoring point k ij Direction rate when the mth step of excavation is completed after layout; is the monitoring point k ij The lateral displacement when the mth step of excavation is completed after layout; is the monitoring point k ij Vertical displacement when the mth step of excavation is completed after layout.

[0091] In this embodiment, the vertical displacement direction rate parameters of each monitoring point are shown in Table 2.

[0092] Table 2 Vertical displacement direction rate parameters of each monitoring point

[0093]

[0094] S5, vertical rate instability criterion for slope monitoring and division of plastic zone.

[0095] When the slope is in the stable elastic stage, the Poisson's ratio of the soil of the slope should be a constant value, and its value is only related to the soil material of the slope. Assume that the simplified model of the landslide is as follows Figure 5 , where the slope angle is θ, the X-axis is parallel to the slope foot, and the Y-axis is perpendicular to the slope surface. A rectangular coordinate system is established, where the corresponding axial strain is ε x , the transverse strain is ε y , now select a point on the surface of the simplified model for analysis.

[0096] Since the Poisson's ratio of the slope is obtained when the soil is only subjected to axial force but no confining pressure, for the points in the simplified landslide model above, which are subjected to the force of the slope surface, it is equivalent to that there is no lateral strain in the soil in contact with the landslide surface, and the lateral strain caused by the downward sliding force is completely perpendicular to the slope surface.

[0097]

[0098] Its vertical displacement rate is:

[0099]

[0100] Then we get:

[0101]

[0102] When the selected landslide is fixed, its slope angle θ is a constant value, and the vertical displacement direction rate at this time is only related to the size of the Poisson's ratio and is a constant value. As the sliding force gradually increases, the structure and properties of the slope will change, and the Poisson's ratio of the slope will gradually increase, so the vertical displacement direction rate at this time will also increase or change suddenly.

[0103] Based on this, the elastic stage Poisson's ratio parameter μ0 and the critical point Poisson's ratio parameter μ between the destruction stage obtained by S1 are 界 , the vertical displacement response rate U0 and U 界 .

[0104] According to the change of displacement response rate of each monitoring point, the displacement change of each monitoring point is determined, the direction rate of each point is calculated, and the stability of each monitoring point is determined. That is, the displacement response rate of the monitoring point is between U0-U 间 When the displacement response rate of a monitoring point fluctuates within the interval, the area where the monitoring point is located is in a relatively stable state; when the displacement response rate of the monitoring point is outside the interval or even changes suddenly, it indicates that there may be a potential plastic zone in the area where the monitoring point is located.

[0105] In this embodiment, the vertical displacement response rate of the slope at the corresponding stage can be obtained as U=0.78, U 界 =0.89, compared with the vertical displacement direction rate of each monitoring point obtained in step S4, it can be seen that the monitoring point k 13 , k 21 ...k 93 There may be a potential plastic zone in the area.

[0106] S6, Determination of critical value of slope damage direction rate.

[0107] According to the basic principles of damage mechanics, the damage process and damage degree can be expressed by the damage variable D.

[0108]

[0109] Where: D is the damage variable; E t E0 is the initial elastic modulus of rock and soil, and E0 is the elastic modulus of rock and soil after damage.

[0110] From the above formula, we can see that when the slope is not damaged, E t =E0, D = 0, when the slope is completely damaged, E t =0, D=1.

[0111] According to the division of the development of the slope plastic zone divided by S5, when the layer belongs to the stable zone, it is recorded as A1, and when the layer is the unstable zone, it is recorded as A2; the number of stable zones and unstable zones is counted and recorded as C1 and C2 respectively. When the slope is not damaged, C2 = 0, D = 0, when the slope is completely damaged, C1 = 0, D = 1.

[0112] The above two equations are equivalent in evaluating the damage deformation law during foundation pit excavation, so the damage variable of the slope is defined as

[0113] According to the importance level of the slope, refer to the relevant slope engineering specifications to set a slope safety factor K for the slope, and then determine the critical value of the damage variable of the slope body. D cr It is the overall stability criterion of the slope determined by the safety factor.

[0114] In this embodiment, according to the development of the slope plastic zone divided by S5, C1=6, C2=21, at this time the damage variable D=0.777, the slope safety factor K in this paper=1.25, based on this damage variable critical value

[0115] S7, determination of overall slope stability and slip surface.

[0116] According to the overall stability criterion of the slope, the stability of the slope is analyzed and evaluated as follows: When the slope damage variable D<D cr When the slope damage variable D>D cr It indicates that the slope is in an unstable state as a whole.

[0117] In this embodiment, it can be seen from S6 that D<D cr , so the slope as a whole is in a relatively stable state.

[0118] The above embodiments are only for illustrating the inventive concept and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made based on the essence of the content of the present invention should be included in the protection scope of the present invention.

Claims

1. A slope stability monitoring and early warning method based on Poisson's ratio loss direction rate, characterized in that: The following steps are involved: Step 1: Determine the Poisson's ratio parameter and critical Poisson's ratio: Drill and sample, and use uniaxial compression test to obtain the lateral strain ε of the original soil and rock during the entire compression test process. y Value and axial strain ε x value, determine the variation law of Poisson's ratio of slope materials, and use the Poisson's ratio formula Determine the Poisson's ratio parameter μ0 and the critical Poisson's ratio μ 界 ; Step 2: Select and arrange excavation displacement monitoring points: Through actual investigation and measurement, obtain the geometric characteristics and geomorphic information of the slope, determine the slope excavation method, arrange monitoring points for the excavated slope to be measured, and obtain the lateral displacement and vertical displacement of the monitoring point position during the entire construction process; Step 3: Record the displacement monitoring data at each monitoring point: According to the construction plan, the displacement response caused by each excavation of the slope is monitored in real time, and the displacement monitoring data transmitted by the displacement monitoring equipment is preprocessed; Step 4: Determine the vertical displacement direction rate parameter of the monitoring point: Based on step 3, Calculate the slope k at each monitoring point during the excavation process ij The displacement direction rate at the completion of the mth step of excavation is: is the direction rate when the mth step of excavation is completed after the monitoring points are arranged, is the lateral displacement when the mth step of excavation is completed after the monitoring points are arranged, is the vertical displacement when the mth step of excavation is completed after the monitoring points are arranged; Step 5: Divide the scope of the slope plastic zone: Conduct instability criterion on the vertical direction rate of the slope monitoring, and determine the scope of the slope plastic zone by establishing the damage direction rate related to the Poisson's ratio and the vertical displacement direction rate; Step 6: Use the basic principles of damage mechanics to determine the critical value of the slope damage direction rate and the overall stability of the slope.

2. The slope stability monitoring and early warning method based on Poisson's ratio loss direction rate according to claim 1 is characterized by: The drilling sampling adopts a stratified sampling method to take original samples in the technical hole according to different strata. The sampling is taken from 1.5 meters below the ground, and the sampling interval is 1-3 meters.

3. The slope stability monitoring and early warning method based on Poisson's ratio loss direction rate according to claim 1 is characterized in that: The step 2 comprises: Step 2-1: Determine the number of excavation levels and the excavation height of each level; Step 2-2: Set up monitoring points in the direction of the vertical and parallel free surface of each step excavated; Step 2-3: Arrange three rows of monitoring points in the horizontal direction, denoted as k ij (i=1,2,…,m;j=1,2,…,m), represents the jth monitoring point in the i-th row; Step 2-4: Use displacement monitoring equipment to obtain the lateral and vertical displacements of the monitoring point during the entire construction process.

4. The slope stability monitoring and early warning method based on Poisson's ratio loss direction rate according to claim 1 is characterized in that: The step 5 comprises: Step 5-1: Set the toe of the slope as θ, set the parallel to the toe of the slope as the X-axis and the perpendicular to the slope as the Y-axis to establish a rectangular coordinate system, where the corresponding axial strain is ε x , the transverse strain is ε y ; Step 5-2: Calculate the vertical displacement direction rate according to Then get Step 5-3: Substitute the Poisson's ratio parameter μ0 and critical Poisson's ratio μ obtained in step 1 界 , substitute into the formula of step 5-2 to determine the vertical displacement response rate U0 of the slope at the corresponding stage and the critical vertical displacement response rate U 界 ; Step 5-4: Determine the displacement change of each monitoring point according to the change of the displacement response rate of each monitoring point, calculate the direction rate of each point and determine the stability of each monitoring point.

5. The slope stability monitoring and early warning method based on Poisson's ratio loss direction rate according to claim 4 is characterized in that: The step 5-4 comprises: When the displacement response rate of a monitoring point is between U0-U 间 When the range fluctuates, the area where the monitoring point is located is in a stable state; When the displacement response rate of a monitoring point is between U0-U 间 When the monitoring point is outside the range or a mutation occurs, there is a potential plastic zone in the area where the monitoring point is located.

6. The slope stability monitoring and early warning method based on Poisson's ratio loss direction rate according to claim 1 is characterized in that: The step 6 comprises: Step 6-1: Based on the basic principles of damage mechanics, the damage variable D is used to represent the damage process and damage degree. Among them, E t Initial elastic modulus of rock and soil, E0 elastic modulus of rock and soil after damage; Step 6-2: When the slope is not damaged, E t =E0, D = 0, when the slope is completely damaged, E t =0, D=1; Step 6-3: According to the range of the slope plastic zone divided in step 5, when the layer belongs to the stable zone, it is recorded as A1, and when the layer is the unstable zone, it is recorded as A2. The number of stable zones and unstable zones is counted and recorded as C1, C 2。 When the slope is not damaged, C2=0, D=0; when the slope is completely damaged, C1=0, D=1; Step 6-4: Based on the equivalence of the above calculations in evaluating the damage deformation law during foundation pit excavation, define the damage variable of the slope According to the importance level of the slope, refer to the relevant slope engineering specifications to set the slope safety factor K for the slope and determine the critical value of the damage variable of the slope body. D cr The overall stability criterion of the slope is determined by using the safety factor.

7. The slope stability monitoring and early warning method based on Poisson's ratio loss direction rate according to claim 6 is characterized in that: The step 6 includes: performing the following analysis and evaluation on the stability of the slope according to the overall stability criterion of the slope.

8. The slope stability monitoring and early warning method based on Poisson's ratio loss direction rate according to claim 7 is characterized in that: When the slope damage variable D<D cr When the slope damage variable D>D cr The slope is in an unstable state as a whole.

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