Rainfall-induced landslide monitoring and early warning method and system

Abstract

The application discloses a rainfall type landslide monitoring and early warning method and system. In view of the defect that the prior art cannot implement monitoring and early warning on landslide disasters by taking groundwater level or pore water pressure dynamic data as input variables, the application utilizes the principle of the groundwater connecting vessel developed in the early stage to solve the technical problem of inverting key characteristic parameters such as the groundwater elevation and the pore water pressure by using the ground trace drainage flow rate dynamic data, and further to solve the technical scheme of calculating the slope safety factor. The application realizes rainfall type landslide monitoring and early warning based on monitoring the ground drainage flow rate, and converts the monitoring and evaluation on the safety and stability of the slope into the monitoring on the flow rate of the ground drainage outlet, which is a novel groundwater monitoring type rainfall type landslide monitoring and early warning technical scheme. The technology can be used for any shape sliding surface, and considers the real-time data of the pore water pressure at the bottom of the sliding surface, has short calculation time and high calculation efficiency, and not only simplifies the monitoring means, but also has higher monitoring precision than the same period rainfall monitoring type technical scheme.

Description

Technical Field

[0001] This invention relates to a landslide monitoring and early warning technology, and in particular to a method and system for monitoring and early warning of rainfall-induced landslides based on the monitoring of the physical characteristics of groundwater on slopes, belonging to the fields of geological disaster prevention and control and geological disaster monitoring and early warning technology. Background Technology

[0002] Landslides are one of the three major types of geological hazards and are an important monitoring and prevention target for environmental safety construction in mountainous areas. While the triggering factors for landslides are diverse, statistics show that over 90% of landslides are rainfall-induced landslides.

[0003] Current research on rainfall-induced landslides generally agrees that rainwater infiltration into the slope increases soil moisture content and may also cause a rise in groundwater levels. On one hand, the increased soil unit weight leads to increased shear stress at the sliding surface; on the other hand, the increased negative pore water pressure in the soil leads to a decrease in shear strength. When the limit equilibrium state is exceeded, slope instability and sliding occur. This means that for rainfall-induced landslides, the most ideal and effective monitoring and early warning scheme should design the input variables of the early warning model at the groundwater level monitoring level, that is, using dynamic monitoring values ​​of parameters such as groundwater level, soil pore water pressure, and soil unit weight as input data. Furthermore, a more preferable approach is to use dynamic groundwater level parameters as the most basic input, and then use these parameters to calculate dynamic soil pore water pressure as a secondary input. However, existing monitoring and early warning schemes for rainfall-induced landslides have not yet realized this technical concept.

[0004] The primary reason why existing technologies cannot effectively monitor and warn of landslide disasters using dynamic data on groundwater level or pore water pressure as input variables lies in the inability to adequately address the technical challenges of dynamic groundwater level monitoring. Currently, groundwater level monitoring is generally conducted using a "deep" method, i.e., drilling holes and installing various sensors to read data from the ground. This measurement method is subject to significant limitations in the field and is difficult to support real-world implementation of on-site solutions. To circumvent this limitation in monitoring and early warning schemes, existing technologies primarily employ models based on the relationship between rainfall intensity and groundwater (such as the Rosso model). First, simulation experiments are used to establish a model of the impact of different rainfall types on groundwater level changes in shallow landslides, and rainfall thresholds are calculated for application in on-site monitoring and early warning. Then, combined with the theory of infinite slopes, a stability calculation model for shallow landslides is established. Finally, dynamic rainfall data is used as the input for on-site landslide monitoring and early warning schemes. The existing technologies “Response of groundwater on slope to rainfall sequence and prediction of landslide stability by rainfall” (Wang Chenxing, Chang’an University, 2023) and “A method for determining rainfall threshold for landslide disaster monitoring and early warning” (CN 201410572819.5) both belong to this type of landslide monitoring and early warning technical solution. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a rainfall-induced landslide monitoring and early warning technology based on the dynamic characteristics of groundwater.

[0006] To achieve the above objectives, the present invention first provides a method for monitoring and early warning of rainfall-induced landslides, the technical solution of which is as follows:

[0007] A method for monitoring and early warning of rainfall-induced landslides, characterized by: acquiring the baseline data of the monitored slope S, and arranging monitoring points P along the groundwater level line within the slope S. i，i＝1，2，...,n Construct a slice model of the slope S with the landslide surface as the lower base, such that each point P... i Corresponding to a soil strip s i Match the slope baseline data to each soil strip. i Monitoring and collecting data at each point P i Dynamic monitoring data D of groundwater physical characteristics, wherein the dynamic monitoring data D includes pore water pressure u i Calculate the safety factor FOS(t) of slope S at time t, and determine the safety stability of slope S at time t based on FOS(t); FOS(t) is expressed according to Equation 1.

[0008]

[0009] In the formula, FOS(t) represents the safety factor of the slope S at time t.

[0010] P θi - Calculate intermediate quantities

[0011] c i , Cohesion (kPa), friction angle (°) of soil at point Pi, and baseline slope data.

[0012] W i b i h i -Earth strips i Self-weight / kN, width / m, average height / m, slope baseline data,

[0013] u it -Point P i Pore ​​water pressure in soil at time t, kPa, dynamic monitoring data D.

[0014] θ i -Earth strips i Bottom point P i The angle between the normal and the vertical line, °, is the base data of the slope.

[0015] The aforementioned method for monitoring and early warning of rainfall-induced landslides establishes a slope stability coefficient calculation model based on a soil strip model of the slope, expressed by the pore water pressure of groundwater at the monitoring site. It utilizes dynamic pore water pressure data to calculate the dynamic characteristics of the slope stability coefficient, thereby assessing the slope's safety and stability. Dynamic pore water pressure data of the soil at the monitoring site is a crucial input variable for this method. It can be collected using existing methods such as in-situ borehole monitoring or determined by combining empirical values ​​with simulation experimental data.

[0016] Because existing technologies for real-time monitoring and acquisition of dynamic data on pore water pressure in underground soil at monitoring sites are not ideal, they can easily become a limiting factor in the accuracy of calculations using Equation 1. Therefore, a further optimization of the above method is to provide a method for calculating pore water pressure using the groundwater elevation at the monitoring site, specifically implemented using the equations in Equation 2. Wherein, γ w -Slope S Groundwater Unit Weight (KN / m) 3 B it -German pressure head height (m) of groundwater at monitoring site at time t, G 2it -Elevation (m) and h of groundwater at monitoring site at time t i -Earth strips i The elevation (m) of the slip surface at time t.

[0017] u it =γ w B it Equation 2-1

[0018] B it =G 2it -h i Equation 2-2

[0019] The above optimization scheme transforms the real-time monitoring problem of soil pore water pressure at the monitoring site into the real-time monitoring problem of groundwater elevation at the monitoring site. It can effectively utilize the fact that the existing monitoring and measurement technologies have a wider variety of real-time groundwater elevation monitoring methods than soil pore water pressure monitoring methods, thereby improving the accuracy of slope safety factor calculation using Equation 1 model.

[0020] Among existing real-time groundwater elevation monitoring technologies, the communicating vessel principle drainage measurement method, which is based on the communicating vessel principle, uses a water pipe to guide groundwater from a permeable cylinder at point Pi to the surface for drainage, and uses the water flow movement characteristics of the drainage outlet to calculate the groundwater level characteristics of Pi, has many technical advantages. A further optimization of the above-mentioned rainfall-induced landslide monitoring and early warning method of this invention is to provide a method for measuring the groundwater elevation at a monitoring point using the communicating vessel principle drainage measurement method. Specifically, the groundwater elevation at the monitoring point is calculated according to Equation 3.

[0021] G2=min(G 2a G2b Equation 3-1

[0022]

[0023] In the formula, G2 represents the groundwater elevation at the monitoring site (m), and G... 2a G 2b -G2 calculates intermediate quantities (m), v - flow velocity at the surface drainage outlet (m / s), λ - friction coefficient of the water guide pipe, C up - Drilling length at point Pi (m), Z - Inner diameter of water guide pipe (m), η up - The local head loss coefficient, Y, of the portion of the water guide pipe inside the permeable cylinder. max - The maximum water lifting height (m) that can be provided by the natural atmospheric pressure at the measurement site, G3 - the maximum elevation of the top of the water pipe (m), η - the local head loss coefficient of the water pipe, G1 - the water level elevation at the drainage outlet (m), g - the gravitational acceleration constant (m / s²). 2 (Where v belongs to the dynamic monitoring data D, λ, C) up 、Z、η up Y max G3, η, and G1 are measurement design and operation parameters, which are design or operation parameters determined based on baseline data, engineering environment, equipment, instruments, and previous experiments before collecting dynamic monitoring data D.

[0024] Equation 3 is used to calculate the groundwater elevation at a groundwater monitoring site by inverting the instantaneous flow velocity when a steady flow forms at the surface drainage outlet. Compared with existing groundwater elevation measurement methods, this method is improved based on long-term indoor experimental data, refining the independent variables of the calculation model. This is mainly in two aspects: first, introducing borehole length as an influencing factor; and second, distinguishing the head loss factor in the water guide pipe, decomposing it into the local head loss coefficient ∑η of the portion of the water guide pipe inside the permeable tube. up The combination of the total local head loss coefficient ∑η and the monitoring flow velocity results in the inversion calculation of groundwater level elevation is more accurate and the calculation error is smaller.

[0025] In the above optimization scheme, there are various existing methods for determining the friction coefficient λ of the water pipe, such as classical equations (Darcy-Weisbach formula, Colebrook formula), experimental methods, empirical formulas, empirical charts, etc. This invention further provides a scheme for calculating the friction coefficient λ of the water pipe. Specifically, it is determined according to Equation 4. Wherein, R... e - Reynolds number, Δ - absolute roughness of the water pipe material (mm), d - characteristic length parameter of the water pipe, valued as inner diameter of the water pipe Z (mm).

[0026]

[0027] In the above optimization scheme, ∑η up The determination of ∑η can be solved using existing methods for calculating head loss coefficients (such as the K-value method, experimental method, empirical formula, CFD simulation, etc.). However, in order to construct a monitoring site pore water pressure measurement method with complete technical logic based on the communicating vessel principle drainage measurement method and improve measurement accuracy, this invention also provides ∑η under this technical logic. up The calculation method for ∑η is specifically determined according to the system of equations 5. Here, η1, η2, and η3 are the three components of the local head loss coefficient ∑η in the water pipe, and r1 is point P. i Drilling radius (m), R - turning radius at the top of the water pipe (m), α - turning angle at the top of the water pipe (°), A - cross-sectional area of ​​the drain outlet (m²) 2 ).

[0028] ∑η=η1+η2+η3 Equation 5-1

[0029] ∑η up =η1+η2 Equation 5-2

[0030]

[0031]

[0032]

[0033] The optimized rainfall-induced landslide monitoring and early warning method of this invention utilizes the communicating vessel principle drainage measurement method to achieve real-time monitoring of groundwater elevation and pore water pressure data at monitoring sites. The data monitoring and acquisition scheme only requires that the pipeline connecting the underground monitoring site and the ground measurement end be unobstructed. After the pipeline is filled and water flow is stable, there is no specific requirement for the outflow volume for each measurement; once the flow velocity is detected, the outflow can be shut off. Therefore, when using a high-precision micro-fluid velocity meter, an extremely thin water pipe can be used, and the detection of the flow velocity v is completed instantaneously, causing negligible disturbance to the groundwater level and soil pore water pressure.

[0034] Based on the above-mentioned method for monitoring and early warning of rainfall-induced landslides, this invention also provides a monitoring and early warning system for rainfall-induced landslides, the technical solution of which is as follows.

[0035] A rainfall-based landslide monitoring and early warning system is characterized by: conducting on-site investigations of the monitored slope S to obtain baseline slope data; and using this baseline data, deploying monitoring points P along the groundwater elevation line within slope S. i，i＝1，2，...，n Construct a slice model of slope S, such that each point P... i Corresponding to a soil strip s i Match the slope baseline data to each soil strip.i At each point P i A borehole was drilled and a permeable cylinder was inserted to ensure that groundwater entered the cylinder. The inlet of the water pipe extended below the liquid level inside the permeable cylinder, and the outlet of the water pipe led to the surface. After the water flow from the outlet stabilized, the monitoring terminal measured and collected P data at each point. i The dynamic monitoring data of groundwater physical characteristics D; the safety factor FOS(t) of slope S at time t is calculated using the above-mentioned rainfall-induced landslide monitoring and early warning method, and the safety stability of slope S is judged.

[0036] In the preferred rainfall-induced landslide monitoring and early warning method of this invention, the dynamic monitoring of groundwater physical characteristics can be completed by collecting the dynamic flow velocity v(t) of the surface drainage outlet using an inversion calculation model. Therefore, in the above-mentioned rainfall-induced landslide monitoring and early warning system, if the communicating vessel principle drainage measurement method is used to monitor and collect the dynamic monitoring data D of each point Pi, the FOS(t) threshold for judging the safety and stability of the slope S can be determined based on the basic data, a safety and stability model of the slope S expressed according to Equation 6 can be constructed, the v threshold for judging the safety and stability of the slope S can be calculated, and the safety and stability of the slope S can be judged based on the dynamic value of the surface drainage outlet flow velocity v and the v threshold in the dynamic monitoring data D; in Equation 6, v(t) is the flow velocity (m / s) of the drainage outlet at time t.

[0037] FOS(t) = v(t) Equation 6

[0038] Regarding the rainfall-induced landslide monitoring and early warning technology of this invention, theoretically, when constructing a slice model of the slope S, the more refined the slice model, the more detailed the soil s... i Quantity and monitoring sites P i The more numerous the monitoring points, the higher the accuracy of the early warning system. However, for homogeneous slopes, such a setup can lead to wasted technology and prolonged monitoring feedback time. Therefore, if the slope S is homogeneous soil, the monitoring point P... i The default settings can be used. The default settings can be: adjacent soil strips s i A total of one monitoring site P was set up. i In the calculation, the same dynamic monitoring data D is matched. The default setting can also be that for monitoring points P arranged along the groundwater level within the slope S... i Only a few of the monitoring sites were used as sampling points P j Sampling point P was collected. j Groundwater dynamic elevation data, using sampling point P j The groundwater dynamic elevation data at time t is used to fit the groundwater elevation curve of slope S at time t, and then the curve equation is used to solve for the non-sampling point P. j Groundwater elevation data at monitoring site Pi at time t. Sampling point P j The quantity is determined based on the amount of data required for fitting the curve.

[0039] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention provides a method for monitoring and early warning of rainfall-induced landslides based on groundwater dynamic monitoring, solving the problem of calculating the slope safety factor using dynamic data of soil pore water pressure at monitoring sites, and monitoring and early warning of rainfall-induced landslide disasters. (2) The key technical problem solved by the present invention is to construct a set of technical solutions that have complete technical logic of the drainage measurement method based on the principle of communicating vessels, and use the flow velocity monitoring of the ground drainage outlet to invert key characteristic parameters of groundwater, and then calculate the slope safety factor. This shifts the monitoring and evaluation of slope safety and stability to the monitoring of the flow velocity of the ground drainage outlet, thereby simplifying the monitoring methods and improving the monitoring accuracy. To this end, each optimization scheme of the present invention further provides the calculation of the local head loss coefficient ∑η of the water guide pipe in the permeable cylinder based on the flow velocity v of the drainage outlet. up (3) The method for calculating the real-time safety factor of slope considering the real-time change of groundwater level is based on the principle of slope sliding body force balance and moment balance. It solves the real-time safety factor of slope by calculating the static balance on each block. This method can be used not only for sliding surfaces of arbitrary shape, but also for real-time changes in pore water pressure at the bottom of the sliding surface. It has a short calculation time and high calculation efficiency. (4) Dynamic changes in groundwater are the most critical factor inducing rainfall-induced landslides. However, due to the lack of economical and effective means of groundwater dynamic monitoring, existing technologies usually use rainfall and displacement, which are easier to obtain dynamic data, as monitoring parameters for disaster early warning. This has led to two major technical types in the existing rainfall-induced landslide monitoring and early warning schemes: rainfall monitoring type and displacement monitoring type. This invention utilizes the previously developed groundwater communication vessel principle drainage measurement method to solve the technical problem of inverting key characteristic parameters of groundwater using dynamic data of trace surface drainage flow velocity. It constructs a technical solution for monitoring and early warning of rainfall-induced landslides based on monitoring surface drainage velocity, representing a completely new groundwater monitoring-based rainfall-induced landslide monitoring and early warning technology, distinct from existing technologies. Furthermore, this invention's groundwater monitoring solution is superior to contemporary rainfall monitoring solutions. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the deployment of monitoring and early warning methods for rainfall-induced landslides.

[0041] Figure 2 This is a partial schematic diagram of the slice model of slope S.

[0042] Figure 3 This is a data chart of the monitoring and early warning plan.

[0043] The numbers in the attached diagram are: 1. Permeable tube; 2. Water pipe; 21. Inlet; 22. Outlet; 3. Borehole; 4. Slope; 5. Landslide surface; 6. Slope groundwater level. Detailed Implementation

[0044] The preferred embodiments of the present invention will now be further described with reference to the accompanying drawings.

[0045] Example 1

[0046] like Figures 1-3 As shown, the method of this invention is used to monitor and provide early warning of the risk of rainfall-induced landslides on a certain slope.

[0047] 1. Layout of the target slope and monitoring instruments

[0048] The monitored slope is located in Quzhou City, Zhejiang Province. The geological structure of the landslide is relatively simple, with a wide rainfall infiltration recharge area at the rear edge of the slope. The slope soil has good permeability, and the groundwater level varies significantly from year to year, making it a typical rainfall-induced landslide. This invention utilizes the technology to monitor and provide early warning of rainfall-induced landslides on this slope by monitoring the surface drainage velocity.

[0049] Conduct on-site investigations to obtain baseline data for the monitoring and early warning plan. The on-site investigation referred to in this technology includes various geological surveys, reconnaissance, mapping, and measurement work at the slope where the project is located, as well as existing simulation experiments, testing experiments, observation experiments, and analytical experiments in the field, acquisition of historical disaster records, relevant technical specifications, and acquisition of experience methods and data that can be used for reference.

[0050] Figure 1 This is a schematic diagram of the deployment of monitoring and early warning methods for rainfall-induced landslides.

[0051] Based on the baseline data from the monitoring plan, the operational parameters for each measurement design were determined (Table 1).

[0052] Based on the baseline data of the slope S, the monitoring object, monitoring points P are arranged along the groundwater level line within the slope S. i，i＝1，2，…n And construct a slice model of the slope S with the landslide surface as the lower base, so that each point P i Corresponding to a soil strip s i Match the slope baseline data to each soil strip. i Inside. Figure 2 This is a schematic diagram of the slice model of slope S.

[0053] In this embodiment, the monitored slope is a homogeneous soil body, therefore the monitoring site Pi uses the default setting. Specifically, some adjacent soil strips share a single monitoring site P, and the same partial measurement design operation parameters and the same dynamic monitoring data D are used in the calculation.

[0054] Determine each point P separately i At the vertical projection point P′ on the slope surface i At each point P′ i Hole 4 was drilled perpendicularly to the slope, to a depth below the groundwater level, with a length C. up Install the permeable cylinder 1 inside borehole 4. Place the permeable cylinder 1 in the borehole, ensuring it is perpendicular to the slope. Extend the water guide pipe 2 into the permeable cylinder 1, with the inlet 21 submerged below the liquid surface inside the core casing. Pull the drain outlet 22 of the water guide pipe 2 above ground level and connect it to the flow velocity meter 4. Ensure the elevation of the inlet 21 is as high as possible. The inner diameter Z of the water guide pipe 2 is less than 5mm. For detailed installation instructions of each component, refer to existing technology (CN 2023114987624, Groundwater Level Elevation Measurement Method, Water Storage Measurement System and Application). In this example, a high-precision micro liquid flow meter is selected as the flow velocity meter.

[0055] After the water pipe 2 is installed, an auxiliary filling water operation is performed at the drain outlet 22. The auxiliary filling water operation can be achieved by evacuating air at the drain outlet to create negative pressure, or by reverse filling water into the pipe from the drain outlet 2. In this example, the auxiliary filling water operation involves giving the drain outlet 21 a certain amount of initial water to guide the drainage to start.

[0056] 2. Monitoring data collection

[0057] The monitoring data D of groundwater characteristics at each point Pi was collected. The monitoring data D includes the flow velocity v at each data collection time t at the drainage outlet 22. i (t). During the monitoring and early warning period, keep the inlet 21 of the water pipe 2 below the liquid level inside the permeable cylinder 1.

[0058] To save space, the following description uses only one time point t in the monitoring scheme as an example. The monitoring scheme can be implemented dynamically, that is, it can be carried out over multiple consecutive time points t.

[0059] The monitoring data is shown in Table 1.

[0060] 3. Inversion Calculation

[0061] This embodiment specifically implements the optimized scheme of the method of the present invention, that is, all intermediate quantities are calculated and determined based on the dynamic characteristics of the water flow at the drainage outlet. Based on the measurement design operation parameters and monitoring data D, the local head loss coefficient ∑η of the portion of the water guide pipe 2 inside the permeable cylinder 1 is calculated according to the system of equations 5. up The local head loss coefficient ∑η of water pipe 2 is calculated. The friction coefficient λ of water pipe 2 is calculated according to Equation 4. The equations in Equation 3 are used to calculate the point P. i Groundwater elevation G at time t 2it The pore water pressure u at point Pi in the soil at time t is calculated using Equation 2. itThe safety factor FOS(t) of the slope S at time t is calculated according to Equation 1. Intermediate and final calculation data are shown in Table 1.

[0062] Table 1 lists the relevant parameter data for soil strips s16 and s17 as examples. The monitoring site P at soil strips s16 and s17... i The default settings were used, which set up a single monitoring site Pi, so some data were identical.

[0063] Table 1 Relevant parameter data

[0064]

[0065] 4. Slope safety and stability assessment

[0066] Based on FOS(t) dynamic data, and referring to the existing FOS landslide risk level classification method, the risk level and warning level of rainfall-induced landslides on the monitored slope S are assessed. Table 2 shows the monitoring and warning level classification.

[0067] Table 2 Classification of Monitoring and Early Warning Levels

[0068] FOS≤1.00 Level III Warning 1.00 < FOS ≤ 1.05 Level II Warning 1.05 < FOS ≤ 1.15 Level 1 warning FOS > 1.15 No warning needed

[0069] 5. Effectiveness of monitoring and early warning technologies

[0070] A two-week monitoring and early warning system was implemented for this slope. Key monitoring data can be found here. Figure 3 . Figure 3 In addition to displaying data curves for the three main parameters of the present invention, data bars of rainfall during the same period are also plotted for comparison. Figure 3 The results showed that rainfall had a poor correlation with landslide stability. On the contrary, the groundwater monitoring-based early warning system was more effective than the rainfall monitoring system in assessing slope stability and disaster risk.

Claims

1. A method for monitoring and early warning of rainfall-induced landslides, characterized in that: Obtain the baseline data of slope S, the monitoring target, and arrange monitoring points along the groundwater level line within slope S. Construct a slice model of the slope S with the landslide surface as the lower base, so that each point... Corresponding to one soil strip Match the slope baseline data to each soil strip Monitoring and collecting data at various points The dynamic monitoring data D of groundwater physical characteristics, including pore water pressure. Calculate the safety factor FOS(t) of slope S at time t, and determine the safety stability of slope S at time t based on FOS(t); FOS(t) is expressed according to Equation 1. Formula 1 In the formula, FOS(t) represents the safety factor of slope S at time t. - Calculate intermediate quantities, , -point Soil cohesion (kPa), friction angle (°), and baseline slope data. , - Dojo Self-weight / kN, width / m, slope baseline data, -point Pore ​​water pressure in soil at time t, kPa, dynamic monitoring data D. - Dojo Bottom point The angle between the normal and the vertical line, °, slope baseline data; The pore water pressure The pore water pressure is calculated using dynamic monitoring data and the system of equations D. , Equation 2-1 Equation 2-2 In the formula, - Slope S groundwater unit weight, kN / m 3 Slope baseline data -point The pressure head height of groundwater at time t, in meters. -point Groundwater elevation at time t, m, monitoring data D, - Dojo Slip surface elevation, m; slope baseline data; The drainage measurement method based on the principle of communicating vessels was used to monitor and collect data at various points. The dynamic monitoring data D, the drainage measurement method based on the principle of communicating vessels is based on the principle of communicating vessels, and uses a water pipe (2) to connect the points The permeable pipe (1) draws groundwater to the surface for drainage, and uses the water flow movement characteristic index of the drainage outlet (22) to back calculate Methods for measuring groundwater level characteristics; point The groundwater elevation was calculated using Equation 3. Equation 3-1 Equation 3-2 In the formula, - Groundwater elevation at monitoring site, m — Calculate the intermediate quantity, m. v - Flow velocity at ground drainage outlet (22), m / s, dynamic monitoring data D, λ – Friction coefficient of the water guide pipe (2), measured as a design operating parameter. -point Drilling length (m), measurement design operating parameters. Z-Water pipe (2) Inner diameter, m, measurement design operating parameters. - The local head loss coefficient of the water guide pipe (2) inside the permeable cylinder (1) is measured according to the design operating parameters. - Measure the maximum water lifting height that the natural atmospheric pressure can provide, in meters, and measure the design operating parameters. - Maximum elevation of the top of the water pipe (2), m, measurement design operating parameters, η – Local head loss coefficient of water pipe (2), measured design operating parameters, - Drainage outlet (22) water level elevation, m, measurement design operation parameters, g - acceleration due to gravity ,constant.

2. The method for monitoring and early warning of rainfall-induced landslides according to claim 1, characterized in that: The friction coefficient λ of the water guide pipe (2) is calculated according to Equation 4. Formula 4 In the formula, - The Reynolds number is determined using existing technology. △-Absolute roughness of the material of the water pipe (2), mm, measurement design operating parameters, d - Characteristic length parameter of water pipe (2), value of inner diameter Z of water pipe (2), mm, measurement design operation parameter.

3. The method for monitoring and early warning of rainfall-induced landslides according to claim 1, characterized in that: The local head loss coefficient of the portion of the water guide pipe (2) inside the permeable cylinder (1) The local head loss coefficient Ση of the water pipe (2) is calculated according to the system of equations 5. Formula 5-1 Formula 5-2 Formula 5-3 Formula 5-4 Formula 5-5 In the formula, , , - The three components of the local head loss coefficient Ση of the water pipe (2) are respectively. -point Drilling radius, in meters, measurement design parameters. R—Water pipe (2) vertex turning radius, m, measurement design operation parameters. α—Water pipe (2) vertex turning angle, °, measurement design operating parameters, A—Cross-sectional area of ​​drain outlet (22), m 2 Measure the design operating parameters.

4. A rainfall-based landslide monitoring and early warning system, characterized in that: A field survey was conducted on slope S to obtain baseline slope data. Based on this data, monitoring sites were established along the groundwater elevation line within slope S. Construct a slice model of slope S, so that each point Corresponding to one soil strip Match the slope baseline data to each soil strip At each point Drill a hole and insert a permeable cylinder (1) to ensure that groundwater enters the permeable cylinder (1). The inlet (21) of the water pipe (2) extends below the liquid level inside the permeable cylinder (1), and the outlet (22) of the water pipe (2) leads to the ground surface. After the outlet (22) stops flowing water stably, the monitoring end measures and collects data at each point. The dynamic monitoring data of groundwater physical characteristics D; the safety factor FOS(t) of slope S at time t is calculated using the rainfall-induced landslide monitoring and early warning method described in any of claims 1 to 3, and the safety stability of slope S is determined.

5. The rainfall-induced landslide monitoring and early warning system according to claim 4, characterized in that: For monitoring and collecting data at various points using the principle of communicating vessels and the drainage measurement method. The technical solution of dynamic monitoring data D is to determine the FOS(t) threshold for judging the safety and stability of slope S based on the basic data, construct the slope S safety and stability model expressed by Equation 6, solve the v threshold for judging the safety and stability of slope S, and judge the safety and stability of slope S based on the dynamic value of the flow velocity v of the ground drainage outlet (22) and the v threshold in the dynamic monitoring data D. Formula 6 In the formula, v(t) is the flow velocity of the drain outlet (22) at time t, m / s, and the dynamic monitoring data is D.

6. The monitoring and early warning method according to any one of claims 1 to 3 or the monitoring and early warning system according to any one of claims 4 to 5, characterized in that: If slope S is homogeneous soil, monitoring sites The default settings are used, where the default settings are adjacent soil strips. A single monitoring site P is set up, and the same dynamic monitoring data D is matched.

7. The monitoring and early warning method or system for rainfall-induced landslides according to claim 6, characterized in that: The default setting is that for monitoring sites arranged along the groundwater level line within slope S... Only a few of the monitoring sites were used as sampling points. Sampling points Groundwater dynamic elevation data, using sampling points The groundwater dynamic elevation data at time t is fitted to the groundwater elevation curve of slope S at time t, and then the curve equation is used to solve for the non-sampling points. monitoring sites Groundwater elevation data at time t.

8. The monitoring and early warning method for rainfall-induced landslides according to any one of claims 1 to 3, or the monitoring and early warning system according to any one of claims 4 to 5, characterized in that: During the monitoring and early warning period, keep the inlet (21) of the water pipe (2) below the liquid level inside the permeable tube (1).

Images