Slope stability evaluation and landslide early warning system and method based on strain monitoring

Abstract

The invention discloses a slope stability evaluation and landslide early warning system and method based on strain monitoring, and relates to the technical field of geotechnical engineering safety monitoring, in the slope stability evaluation system, strain monitoring optical cables are arranged in a plurality of drill holes formed in a slope in a penetrating mode and are fully coupled with slope soil; laser is emitted to the strain monitoring optical cable through a Brillouin optical time domain reflectometer, and a Brillouin scattering light signal is received from the strain monitoring optical cable; brillouin frequency shift is determined according to the Brillouin scattered light signals, then transverse shear force is determined according to the Brillouin frequency shift, the slope stability coefficient of the slope is calculated according to the change of the transverse shear force, and whether landslide is likely to happen or not is further judged in combination with soil humidity measured by the humidity monitoring optical cable, and early warning is conducted in time. Compared with an existing slope monitoring technology, the slope monitoring system has the advantages of being high in precision, wide in monitoring range, resistant to electromagnetic interference, resistant to corrosion and the like, and real-time effective monitoring of different deformation stages of a slope can be achieved.

Description

Technical Field

[0001] The present application relates to the technical field of geotechnical engineering safety monitoring, and in particular to a slope stability assessment and landslide early warning system and method based on strain monitoring. Background Art

[0002] Geological disasters have long plagued human safety production activities and are very likely to cause huge casualties and property losses. The monitoring, early warning and analysis of large deformation disasters, slopes and landslides caused by slope engineering excavation through landslide geological disaster prevention and control technology and landslide disaster prevention and mitigation technology has always been a long-term and arduous challenge faced by the geotechnical engineering community.

[0003] The deformation of the sliding zone or sliding surface is a precursor to the destruction of the landslide. Timely monitoring of landslide deformation and assessment of its stability can provide early warning to prevent casualties and property losses. The current slope monitoring methods such as GPS, 3D laser scanning technology, InSAR and other technologies are susceptible to weather influences and large displacement errors. Therefore, how to provide a slope stability assessment and landslide early warning technology with many advantages such as high monitoring accuracy, wide monitoring range, anti-electromagnetic interference, and anti-corrosion is very necessary for the development of this field. Summary of the invention

[0004] The purpose of this application is to provide a slope stability assessment and landslide early warning system and method based on strain monitoring, which can realize real-time and effective monitoring of different deformation stages of the slope.

[0005] To achieve the above objectives, this application provides the following solutions:

[0006] In a first aspect, the present application provides a slope stability assessment system based on strain monitoring, comprising: a strain monitoring optical cable, a Brillouin optical time domain reflectometer and a computer terminal; the strain monitoring optical cable is arranged to pass through a plurality of boreholes opened on the slope and is fully coupled with the slope soil; a plurality of boreholes are opened at equal intervals on the center line of the slope, and the opening direction of the boreholes is perpendicular to the surface of the slope; the Brillouin optical time domain reflectometer is connected to one end of the strain monitoring optical cable, and the Brillouin optical time domain reflectometer is used to emit a laser into the strain monitoring optical cable and receive a Brillouin scattered light signal from the strain monitoring optical cable; the signal output end of the Brillouin optical time domain reflectometer is signal-connected to the computer terminal; the computer terminal is used to: determine the Brillouin frequency shift according to the Brillouin scattered light signal, determine the axial strain according to the relationship between the Brillouin frequency shift and the axial strain of the strain monitoring optical cable, determine the lateral displacement according to the axial strain, determine the lateral shear force according to the lateral displacement, and calculate the slope stability coefficient of the slope according to the change of the lateral shear force.

[0007] Optionally, it also includes: a temperature compensation optical cable and a first spectrum demodulator; the temperature compensation optical cable is parallel to the extension direction of the strain monitoring optical cable, and is also arranged to pass through a number of boreholes opened on the slope, and is fully coupled with the slope soil; the first spectrum demodulator is connected to one end of the temperature compensation optical cable, and the signal output end of the first spectrum demodulator is connected to the computer terminal; the computer terminal is used to perform temperature compensation on the Brillouin scattering light signal according to the monitoring signal of the temperature compensation optical cable on the ambient temperature change.

[0008] Optionally, two adjacent boreholes are connected via a trench opened on the midline of the slope surface, and after extending from the first borehole, the strain monitoring optical cable lies on the trench surface and extends into the second borehole.

[0009] Optionally, steel bar anchors are fixed at both ends of the trench near the drilled holes. After the strain monitoring optical cable extends out of the first drilled hole, it is wrapped and fixed on the first steel bar rivet, extends along the surface of the trench, and then is wrapped and fixed on the second steel bar rivet and extends into the second drilled hole.

[0010] Optionally, the strain monitoring optical cable is arranged in an S-shape in an S-shaped trench opened on the surface of the slope and is fully coupled with the soil on the surface of the slope; the plane formed by the S-shaped trench is parallel to the surface of the slope and has the center line of the slope as the center line.

[0011] In a second aspect, the present application provides a slope stability assessment method based on strain monitoring, comprising the following steps:

[0012] A laser is emitted into the strain monitoring optical cable, and a Brillouin scattered light signal is received from the strain monitoring optical cable.

[0013] A Brillouin frequency shift is determined based on the Brillouin scattered light signal.

[0014] The axial strain is determined based on the relationship between the Brillouin frequency shift and the axial strain of the strain monitoring optical cable.

[0015] A lateral displacement is determined based on the axial strain, and a lateral shear force is determined based on the lateral displacement.

[0016] The slope stability coefficient of the slope is determined according to the change of the lateral shear force.

[0017] In the third aspect, the present application provides a landslide warning system based on strain monitoring, comprising: a slope stability assessment system based on strain monitoring, a humidity monitoring optical cable and a second spectrum demodulator as described above; the humidity monitoring optical cable is parallel to the extension direction of the strain monitoring optical cable, and is also arranged to pass through a number of drill holes opened on the slope, and is fully coupled with the slope soil; the second spectrum demodulator is connected to one end of the humidity monitoring optical cable, and the second spectrum demodulator is used to determine the soil moisture of the slope through the signal of the humidity monitoring optical cable; the signal output end of the second spectrum demodulator is connected to a computer terminal; the computer terminal is used to judge whether a landslide is likely to occur and to provide a timely landslide warning based on the soil moisture of the slope and the slope stability coefficient of the slope.

[0018] Optionally, the humidity monitoring optical cable, the temperature compensation optical fiber and the strain monitoring optical cable are arranged in an S-shape in an S-shaped trench opened on the surface of the slope, and are fully coupled with the soil on the surface of the slope; the plane formed by the S-shaped trench is parallel to the surface of the slope, and has the center line of the slope as the center line.

[0019] Optionally, the humidity monitoring optical cable, the temperature compensating optical fiber and the strain monitoring optical cable are covered with protective covers, the humidity monitoring optical cable, the temperature compensating optical fiber and the strain monitoring optical cable are distributed in three points in the cross section, and the gaps in the protective covers are filled with slope soil.

[0020] In a fourth aspect, the present application provides a landslide early warning method based on strain monitoring, comprising the following steps:

[0021] The slope stability coefficient of the slope is determined by the slope stability assessment system based on strain monitoring as described above.

[0022] The soil moisture of the slope is determined by a second spectrum demodulator and a moisture monitoring optical cable.

[0023] Based on the soil moisture of the slope and the slope stability coefficient of the slope, it is determined whether a landslide is likely to occur and a landslide warning can be issued in a timely manner.

[0024] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0025] The present application provides a slope stability assessment and landslide warning system and method based on strain monitoring. The slope stability assessment system includes: a strain monitoring optical cable, a Brillouin optical time-domain reflectometer and a computer terminal; the strain monitoring optical cable is arranged through a plurality of boreholes opened on the slope and is fully coupled with the slope soil; the Brillouin optical time-domain reflectometer is connected to one end of the strain monitoring optical cable, and the Brillouin optical time-domain reflectometer is used to emit a laser into the strain monitoring optical cable and receive a Brillouin scattered light signal from the strain monitoring optical cable; the Brillouin frequency shift is determined according to the Brillouin scattered light signal, the axial strain is determined according to the relationship between the Brillouin frequency shift and the axial strain of the strain monitoring optical cable, the lateral displacement is determined according to the axial strain, and the lateral shear force is determined according to the lateral displacement, and the slope stability coefficient of the slope is calculated according to the change of the lateral shear force. In the landslide warning system, the soil moisture measured by the humidity monitoring optical cable is combined to judge whether a landslide is likely to occur and to give a landslide warning in time. The slope stability assessment system based on strain force monitoring and analysis in this application can penetrate into the slope soil layer and accurately analyze the displacement activities of each soil layer. By calculating the lateral shear force and displacement of its sliding zone, the stability of the slope is determined and can be used for early warning. Compared with existing slope monitoring technologies such as GPS, three-dimensional laser scanning technology, InSAR, etc., it has many advantages such as high accuracy, wide monitoring range, anti-electromagnetic interference, and anti-corrosion. It can realize real-time and effective monitoring of different deformation stages of the slope. The system realizes scientific evaluation of slope stability and timely early warning and forecast of landslides, which helps to prevent casualties and property losses. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic structural diagram of a slope stability assessment system based on strain monitoring provided in one embodiment of the present application.

[0028] Figure 2 A schematic diagram of fixing an optical cable by a steel bar anchor in a slope stability assessment system based on strain monitoring provided by an embodiment of the present application.

[0029] Figure 3 A schematic diagram of a strain monitoring optical cable in a slope stability assessment system based on strain monitoring provided in an embodiment of the present application, arranged in an S-shape in an S-shaped trench.

[0030] Figure 4A schematic flow chart of a slope stability assessment method based on strain monitoring provided in one embodiment of the present application.

[0031] Figure 5 A schematic structural diagram of a slope simulation system to which a landslide early warning system based on strain monitoring is applied, provided in one embodiment of the present application.

[0032] Figure 6 A schematic cross-sectional diagram of the distribution of three optical cables in a protective casing in a landslide early warning system based on strain monitoring provided in one embodiment of the present application.

[0033] Figure 7 A flow chart of a landslide early warning method based on strain monitoring provided in one embodiment of the present application.

[0034] Figure 8 A schematic diagram of the structure of a computer device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0036] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0037] In an exemplary embodiment, Figure 1 As shown, a slope stability assessment system based on strain monitoring is provided, including: a strain monitoring optical cable, a Brillouin optical time domain reflectometer and a computer terminal; the strain monitoring optical cable is arranged through a plurality of boreholes opened on the slope and is fully coupled with the slope soil; a plurality of boreholes are opened at equal intervals on the center line of the slope, and the opening direction of the boreholes is perpendicular to the surface of the slope; the Brillouin optical time domain reflectometer is connected to one end of the strain monitoring optical cable, and the Brillouin optical time domain reflectometer is used to emit laser into the strain monitoring optical cable and receive Brillouin scattered light signals from the strain monitoring optical cable; the signal output end of the Brillouin optical time domain reflectometer is connected to the computer terminal signal; the computer terminal is used to: determine the Brillouin frequency shift according to the Brillouin scattered light signal, determine the axial strain according to the relationship between the Brillouin frequency shift and the axial strain of the strain monitoring optical cable, determine the lateral displacement according to the axial strain, determine the lateral shear force according to the lateral displacement, and calculate the slope stability coefficient of the slope according to the change of the lateral shear force.

[0038] In this system, distributed strain monitoring optical cables are similar to human nerves and can capture slight activities in a distributed sensing and near real-time manner. They can monitor the deformation of the sliding zone or sliding surface and understand the evolution stage and inducing factors of the landslide.

[0039] In a specific embodiment, the spatial resolution of the Brillouin optical time domain reflectometer used is 1m, the maximum measurement length can reach 20km, the strain sensing range is 8000με (expandable), the strain sensing accuracy is better than 20μ, the temperature sensing range is -100℃~300℃ (depending on the sensing optical cable), and the temperature sensing accuracy is better than 1℃. After the strain monitoring optical cable port is connected to the Brillouin optical time domain reflectometer, the strain monitoring optical cable is buried in the drill hole of the soil layer. When there is a slight pressure strain on the slope, the Brillouin optical time domain reflectometer will have a spectral frequency shift feedback to detect the location of the pressure strain.

[0040] After field investigation and terrain assessment, the slope is about 26°, and the distance from the bottom to the top is about 200m. The diameter of the drill hole is about 100mm, the drill hole is perpendicular to the slope, the drill hole depth is 30-40cm below the bedrock layer, and the drill hole position is almost on the center line of the slope. The first drill hole is located 20 meters from the top of the slope, and then drill holes along the center line of the slope toward the bottom of the slope, one drill hole every 20 meters, a total of 8 holes.

[0041] As an improved embodiment, the slope stability assessment system based on strain monitoring also includes: a temperature compensation optical cable and a first spectrum demodulator; the temperature compensation optical cable is parallel to the extension direction of the strain monitoring optical cable, and is also arranged to pass through a number of boreholes opened on the slope and is fully coupled with the slope soil; the first spectrum demodulator is connected to one end of the temperature compensation optical cable, and the signal output end of the first spectrum demodulator is connected to a computer terminal; the computer terminal is used to perform temperature compensation on the Brillouin scattering light signal based on the monitoring signal of the temperature compensation optical cable on the ambient temperature change.

[0042] The inhomogeneity that often exists inside the optical cable causes light to scatter in the optical fiber. Brillouin scattering is one of the scattering phenomena. The frequency of the Brillouin scattered light deviates from the incident light. The frequency difference is called the Brillouin frequency shift. Changes in ambient temperature and optical fiber strain will affect the speed of sound and the refractive index of light in the optical fiber, thereby changing the frequency shift of Brillouin scattering. The change in frequency shift is linearly related to the temperature change and axial strain of the optical fiber, that is, Δν=C ε *Δε+C T *ΔT, where Δε and ΔT represent the change in strain and temperature, respectively, C ε and C T denote the strain and temperature coefficients of the Brillouin frequency shift, respectively.

[0043] Specifically in this embodiment, two adjacent boreholes are connected through a trench opened on the midline of the slope surface. After the strain monitoring optical cable extends from the first borehole, it lies on the surface of the trench and extends into the second borehole. Specifically in this embodiment, the depth of the trench is about 30 cm, and the boreholes are connected by the trench. The depth and diameter of the boreholes are determined according to the soil quality of the soil layer, and the boreholes are perpendicular to the slope surface.

[0044] In order to better fix the monitoring optical cable, steel bar anchors are fixed at both ends of the trench near the drilled holes. After the strain monitoring optical cable extends out of the first drilled hole, it is wrapped and fixed on the first steel bar rivet, and then extends along the surface of the trench. After it is wrapped and fixed on the second steel bar rivet, it extends into the second drilled hole. Figure 2 As shown, the length of the steel anchor is about 75cm. It is driven into the soil trench and the optical cable is fixed and wrapped around it. A steel anchor is driven in every 20m. Its function is to prevent the optical cable in the trench from slipping or shifting due to external factors, which may cause accidental errors in the measurement data.

[0045] In another exemplary embodiment of the present application, the strain monitoring optical cable is arranged in an S-shaped trench opened on the surface of the slope and is fully coupled with the soil on the surface of the slope; the plane formed by the S-shaped trench is parallel to the surface of the slope and takes the center line of the slope as the center line, such as Figure 3 In this embodiment, the optical cables only need to be horizontally distributed in the S-shaped trench on the slope without drilling holes.

[0046] Based on the same inventive concept as the above embodiments, the present application also provides a slope stability assessment method based on strain monitoring, such as Figure 4 The flowchart shown includes the following steps:

[0047] A1. Launch laser into the strain monitoring optical cable and receive Brillouin scattered light signal from the strain monitoring optical cable.

[0048] A2. Determine the Brillouin frequency shift according to the Brillouin scattered light signal.

[0049] A3. Determine the axial strain based on the relationship between the Brillouin frequency shift and the axial strain of the strain monitoring optical cable.

[0050] A4. Determine the lateral displacement according to the axial strain, and determine the lateral shear force according to the lateral displacement.

[0051] In this embodiment, the true value of the axial strain of the optical cable is calculated by the pressure strain frequency shift obtained by the Brillouin optical time domain reflectometer and the temperature compensation frequency shift obtained by the first spectrum demodulator, and then the corresponding lateral displacement and the magnitude of the lateral shear force are calculated by the strain magnitude and the shear force model. Specifically, the magnitude of the lateral shear force can be calculated by the following formula:

[0052]

[0053] In the formula, τ mob,i is the lateral shear force of the soil at node i, u s-mob,i represents the shear displacement of the soil at node i, K s,i is the shear stiffness of the soil at node i, u is the shear displacement, u y and τ r They correspond to the yield displacement and residual strength of the soil at node i respectively. Parameters u0 and m can be determined by the following formula:

[0054]

[0055] Among them, u p and τ p are the yield displacement and peak shear strength at the peak point of the τ-u curve, respectively.

[0056] Parameter K s,i 、u y and τ r Generally, it has an obvious linear relationship with the normal stress. According to the geological profile and mechanical properties of the landslide, the normal stress on the sliding surface can be estimated and the parameter K can be determined. s,i 、u y and τ r .

[0057] A5. Determine the slope stability coefficient of the slope based on the change in the lateral shear force.

[0058] The slope stability coefficient is calculated by the following formula:

[0059]

[0060] In the formula, τ 0,i is the initial shear stress of the soil at node i.

[0061] Based on the slope stability assessment system based on strain monitoring provided by the above-mentioned embodiments, the present application also provides a landslide early warning system based on strain monitoring, comprising: the slope stability assessment system based on strain monitoring, a humidity monitoring optical cable and a second spectrum demodulator as provided in the previous embodiments; the humidity monitoring optical cable is parallel to the extension direction of the strain monitoring optical cable, and is also arranged to pass through a number of boreholes opened on the slope, and is fully coupled with the slope soil; the second spectrum demodulator is connected to one end of the humidity monitoring optical cable, and the second spectrum demodulator is used to determine the soil moisture of the slope through the signal of the humidity monitoring optical cable; the signal output end of the second spectrum demodulator is connected to a computer terminal; the computer terminal is used to judge whether a landslide is likely to occur and to provide a timely landslide early warning based on the soil moisture of the slope and the slope stability coefficient of the slope.

[0062] The landslide early warning system uses a slope simulation system, such as Figure 5 As shown, the slope simulation system consists of two movable boxes, in which slope accumulation soil is filled to simulate the real slope; there are two cameras above the boxes to monitor the changes in the simulated slope when the environment changes; the air shower above the box simulates the real rainfall and wind conditions, and can control the wind force and rainfall at any time; the thrust gauge on the right box can move the right box forward and backward by twisting the lever, thereby simulating the shear displacement of the real slope; the inclinometer can adjust the inclination angle of the box to simulate slopes of different angles in the real environment.

[0063] The layout of the optical cables requires full-coring drilling of the soil layer. The three optical cables are distributed in an equilateral triangle and nested in a PVC pipe. The local soil is used to fill the pipe so that the soil and the three optical cables are well coupled and buried in the borehole. The strain optical cable is connected to the indoor Brillouin optical time domain reflectometer, and the temperature compensation optical cable and humidity detection optical cable are connected to the fiber optic demodulator.

[0064] When the laser pulse in the Brillouin optical time-domain reflectometer enters the optical fiber, some Brillouin scattered light will return to the input end for measurement and interpretation. Brillouin scattered light is caused by the nonlinear interaction between the incident light and the photons excited in the light propagation medium. This scattered light changes frequency through Brillouin shift and propagates in the opposite direction of the incident light. Since the strain and temperature along the optical cable affect the backscattered signal at the same time, temperature compensation is usually required during the strain measurement process. The temperature compensation optical cable here is designed to be sensitive only to temperature. After temperature compensation, the Brillouin frequency shift is only linearly related to the axial strain of the distributed strain sensing optical cable, so its axial strain distribution can be measured. The axial displacement and lateral displacement are then derived from the axial strain, and finally the magnitude of the lateral shear force is derived from the lateral displacement. The slope stability coefficient is calculated by the change in the lateral shear force, so as to determine whether the slope is in a stable state.

[0065] In another exemplary embodiment of the present application, the humidity monitoring optical cable, the temperature compensation optical fiber and the strain monitoring optical cable are arranged in an S-shaped trench opened on the surface of the slope, and are fully coupled with the soil on the surface of the slope; the plane formed by the S-shaped trench is parallel to the surface of the slope, and the center line is the center line of the slope. In this embodiment, the optical cables only need to be horizontally distributed in the S-shaped trench on the slope, without drilling.

[0066] Specifically in this embodiment, the humidity monitoring optical cable, temperature compensation optical fiber and strain monitoring optical cable are covered with protective covers. The humidity monitoring optical cable, temperature compensation optical fiber and strain monitoring optical cable are distributed in a three-point pattern on the cross section, and the gaps in the protective covers are filled with slope soil. The protective cover is made of PVC with a diameter of 35mm. The three optical cables are placed in an equilateral triangle shape. The optical cables do not contact the inner wall of the protective cover, and are filled with fine soil and sand to achieve good coupling between the optical cables and the soil. At the same time, the three optical cables need to be stretched as straight as possible so that the optical cables will not slide in the protective cover. Figure 6 shown.

[0067] Based on the same inventive concept as the above embodiment, this embodiment provides a landslide early warning method based on strain monitoring, such as Figure 7 The flowchart shown includes the following steps:

[0068] B1. Determine the slope stability coefficient of the slope by using the slope stability assessment system based on strain monitoring as provided in the above embodiments.

[0069] B2. Determine the soil moisture of the slope through the second spectrum demodulator and humidity monitoring optical cable.

[0070] B3. Determine whether a landslide is likely to occur based on the soil moisture and slope stability coefficient of the slope and issue a landslide warning in a timely manner.

[0071] Through the slope stability assessment system based on strain monitoring as provided in the above embodiment, the true value of the strain measurement is obtained as the axial strain characteristic value at the borehole. The magnitude of the lateral shear force and the lateral shear force displacement can be obtained through the constitutive relationship between shear stress and strain. The strain-related safety factor K value can be obtained by the ratio of the sum of the shear stress mobilized at a certain shear strain level to the sum of the initial shear stress, thereby realizing the judgment of the slope stability and making a timely warning.

[0072] At the same time, humidity is also one of the factors that affect slope stability. The higher the humidity, the greater the chance of slope sliding. This phenomenon is mainly because in a high humidity environment, moisture increases the pressure and stress inside the soil and rock, and the weathering rate of the soil and rock is accelerated, causing the mountain structure to gradually become loose and fragile, reducing its stability, thereby increasing the risk of landslides. At the same time, heavy rainfall or long-term wet conditions will soften the soil and reduce its bearing capacity. When the strength of the soil is not enough to support the weight of the overlying soil or rock layer, a landslide may occur. In this landslide early warning system, soil moisture is monitored in real time and the rainfall weather of the slope is evaluated to ensure the comprehensiveness of the slope experiment.

[0073] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Figure 8As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a landslide early warning method based on strain monitoring or a slope stability assessment method based on strain monitoring is implemented.

[0074] Those skilled in the art will understand that Figure 8 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0075] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0076] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A slope stability assessment system based on strain monitoring, characterized in that: include: A strain monitoring optical cable, a Brillouin optical time domain reflectometer and a computer terminal; the strain monitoring optical cable is arranged through a plurality of boreholes opened on the slope and is fully coupled with the slope soil; a plurality of boreholes are opened at equal intervals on the center line of the slope, and the opening direction of the boreholes is perpendicular to the surface of the slope; the Brillouin optical time domain reflectometer is connected to one end of the strain monitoring optical cable, and the Brillouin optical time domain reflectometer is used to emit laser into the strain monitoring optical cable and receive Brillouin scattered light signals from the strain monitoring optical cable; the signal output end of the Brillouin optical time domain reflectometer is signal-connected to the computer terminal; the computer terminal is used to: determine the Brillouin frequency shift according to the Brillouin scattered light signal, determine the axial strain according to the relationship between the Brillouin frequency shift and the axial strain of the strain monitoring optical cable, determine the lateral displacement according to the axial strain, determine the lateral shear force according to the lateral displacement, and calculate the slope stability coefficient of the slope according to the change of the lateral shear force.

2. The slope stability assessment method based on strain monitoring according to claim 1 is characterized in that: Also includes: Temperature compensation optical cable and first optical spectrum demodulator; The temperature compensation optical cable is parallel to the extension direction of the strain monitoring optical cable, and is also arranged to pass through a number of boreholes opened on the slope and is fully coupled with the slope soil; the first spectrum demodulator is connected to one end of the temperature compensation optical cable, and the signal output end of the first spectrum demodulator is connected to the computer terminal; the computer terminal is used to perform temperature compensation on the Brillouin scattering light signal based on the monitoring signal of the temperature compensation optical cable on the ambient temperature change.

3. The slope stability assessment method based on strain monitoring according to claim 1 is characterized in that: Two adjacent boreholes are connected through a trench opened on the midline of the slope surface. After extending from the first borehole, the strain monitoring optical cable lies on the surface of the trench and extends into the second borehole.

4. The slope stability assessment method based on strain monitoring according to claim 3 is characterized in that: Steel bar anchors are fixed at both ends of the trench near the drilled holes. After the strain monitoring optical cable extends out of the first drilled hole, it is wrapped and fixed on the first steel bar rivet, extends along the surface of the trench, and then is wrapped and fixed on the second steel bar rivet and extends into the second drilled hole.

5. The slope stability assessment system based on strain monitoring according to claim 1 is characterized in that: The strain monitoring optical cable is arranged in an S-shape in an S-shaped trench opened on the surface of the slope and is fully coupled with the soil on the surface of the slope; the plane formed by the S-shaped trench is parallel to the surface of the slope and takes the center line of the slope as the center line.

6. A slope stability assessment method based on strain monitoring, characterized in that: include: emitting laser light into a strain monitoring optical cable, and receiving a Brillouin scattered light signal from the strain monitoring optical cable; Determining a Brillouin frequency shift according to the Brillouin scattered light signal; Determine the axial strain according to the relationship between the Brillouin frequency shift and the axial strain of the strain monitoring optical cable; determining a lateral displacement based on the axial strain, and determining a lateral shear force based on the lateral displacement; The slope stability coefficient of the slope is determined according to the change of the lateral shear force.

7. A landslide early warning system based on strain monitoring, characterized in that: include: The slope stability assessment system based on strain monitoring, the humidity monitoring optical cable and the second spectrum demodulator as described in any one of claims 1 to 5; The humidity monitoring optical cable is parallel to the extension direction of the strain monitoring optical cable, and is also arranged through a number of boreholes opened on the slope, and is fully coupled with the slope soil; the second spectrum demodulator is connected to one end of the humidity monitoring optical cable, and the second spectrum demodulator is used to determine the soil moisture of the slope through the signal of the humidity monitoring optical cable; The signal output end of the second spectrum demodulator is connected to a computer terminal; the computer terminal is used to determine whether a landslide is likely to occur and to issue a landslide warning in a timely manner according to the soil moisture of the slope and the slope stability coefficient of the slope.

8. The landslide early warning system based on strain monitoring according to claim 7 is characterized in that: The humidity monitoring optical cable, the temperature compensation optical fiber and the strain monitoring optical cable are arranged in an S-shape in an S-shaped trench opened on the surface of the slope, and are fully coupled with the soil on the surface of the slope; the plane formed by the S-shaped trench is parallel to the surface of the slope, and takes the center line of the slope as the center line.

9. The landslide early warning system based on strain monitoring according to claim 8 is characterized in that: The humidity monitoring optical cable, the temperature compensating optical fiber and the strain monitoring optical cable are covered with protective covers, the humidity monitoring optical cable, the temperature compensating optical fiber and the strain monitoring optical cable are distributed in three points on the cross section, and the gaps in the protective covers are filled with slope soil.

10. A landslide early warning method based on strain monitoring, characterized in that: include: Determining a slope stability coefficient of the slope by using the slope stability assessment system based on strain monitoring as described in any one of claims 1 to 5; Determine the soil moisture of the slope through the second spectrum demodulator and the moisture monitoring optical cable; Based on the soil moisture of the slope and the slope stability coefficient of the slope, it is determined whether a landslide is likely to occur and a landslide warning can be issued in a timely manner.

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