Rainfall-induced landslide monitoring and early warning method and system

Abstract

To disclose a rainfall-induced landslide monitoring and early warning method and system based on the dynamic characteristics of groundwater.SOLUTION: According to one embodiment, rainfall-induced landslide monitoring and early warning is realized based on monitoring the surface drainage flow rate, and monitoring evaluation of slope safety and stability is transferred to monitoring the flow rate at a surface drainage outlet, thereby disclosing a completely new groundwater-monitoring-based rainfall-induced landslide monitoring and early warning technology. This technology can be used for slide surfaces of any shape, and takes into account real-time data on pore water pressure at the bottom of a slide surface, resulting in short calculation times, high calculation efficiency, and simplified monitoring means, as well as higher monitoring accuracy than that of concurrent rainfall-monitoring-based technologies.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to landslide monitoring and early warning technology, and particularly to a rainfall-induced landslide monitoring and early warning method and system realized 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 Art

[0002] Landslide is one of the three types of geological disasters and an important monitoring and control target for environmental safety construction in mountainous areas. The inducing factors of landslides are diverse, but according to statistical data, more than 90% of landslides belong to rainfall-induced landslides.

[0003] The general understanding of conventional rainfall-induced landslide research is that when rainwater infiltrates into the slope, the water content of the soil mass increases, and at the same time, it may also cause an increase in the groundwater level. While the shear stress of the slip surface increases due to the increase in the bulk density of the soil mass, the shear strength decreases due to the increase in the negative pore water pressure in the soil mass. When the critical balance state is exceeded, unstable sliding of the slope is caused. This means that for rainfall-induced landslides, the most ideal and effective monitoring and early warning plan is to design the input variables of the early warning model at the groundwater level monitoring level, that is, the dynamic monitoring values of parameters such as groundwater level parameters, pore water pressure of the soil mass, and bulk density of the soil mass should be used as input data. Moreover, more preferably, with the dynamic groundwater level parameter as the most basic input, the dynamic pore water pressure of the soil mass is calculated as the secondary input using the dynamic groundwater level parameter. However, the conventional rainfall-induced landslide monitoring and early warning plan has not yet realized this technical concept.

[0004] The most main reason why the conventional technology cannot realize the monitoring and early warning of landslide disasters with the dynamic data of the groundwater level or pore water pressure as input variables is that it cannot well solve the technical problems of the dynamic monitoring of the groundwater level. The current monitoring of the groundwater level is generally carried out in the "buried depth" method, that is, drilling holes and installing various sensors, and reading the sensor data on the ground. Such a measurement method has many limitations in the field and is difficult to support the actual operation of the plan on site. In order to avoid this link in the monitoring and early warning plan, the concept adopted by the conventional technology is mainly based on the relationship model between rainfall intensity and groundwater (such as the Rosso model). First, establish the influence model of different rainfall types on the change of the shallow landslide groundwater level through simulation experiments, calculate the rainfall threshold and apply it to the on-site monitoring and early warning, and then combine the infinite slope theory to establish the stability calculation model of the shallow landslide. Finally, use the rainfall dynamic data as the input of the on-site landslide monitoring and early warning plan. The "Response of Slope Groundwater to Rainfall Sequences and Prediction of Rainfall Landslide Stability" (Wang Chenxing, Chang'an University, 2023) and "Method for Judging Rainfall Threshold for Landslide Disaster Monitoring and Early Warning" (CN 201410572819.5) of the conventional technology both belong to such technical solutions for landslide monitoring and early warning.

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of the deficiencies of the conventional technology, the purpose of the present invention is to provide a rainfall-induced landslide monitoring and early warning technology based on the dynamic characteristics of groundwater.

Means for Solving the Problems

[0006] In order to achieve the above object, the present invention first provides a rainfall-induced landslide monitoring and early warning method, and its technical solution is as follows.

[0007] A rainfall-induced landslide monitoring and early warning method, which acquires background data of the slope body of the slope body S to be monitored and is along the groundwater level line in the slope body S Based on JPEG2025113090000002.jpg45170FOS(t), the safety and stability of the slope body S at time t are judged. FOS(t) is expressed by Equation 1 In the formula in JPEG2025113090000003.jpg32170, FOS(t) is the safety factor of slope S at time t JPEG2025113090000004.jpg75170

[0008] The above rainfall-induced landslide monitoring and early warning method is to establish a slope stability coefficient calculation model expressed by the pore water pressure of the groundwater at the slope monitoring site based on the slope slice model, and use the dynamic data of the pore water pressure to measure the dynamic characteristics of the slope stability coefficient, thereby evaluating the safety and stability of the slope. The dynamic data of the pore water pressure of the soil body at the monitoring site is an important input variable of the above method, and can be collected by adopting the in-situ boring hole instrument monitoring means using the conventional method, or can also be determined by combining empirical values and simulation experiment data

[0009] Due to the fact that the effect of real-time monitoring and collection of the dynamic data of the pore water pressure of the soil body in the underground part by the conventional technology is not ideal, it is easy to become a limiting condition for the calculation accuracy of the model of Equation 1. Therefore, a further optimization of the above method is to provide a method for measuring the pore water pressure by using the groundwater elevation at the monitoring site, and specifically, it is implemented by adopting the system of equations of Equation 2 JPEG2025113090000005.jpg28170

[0010] JPEG2025113090000006.jpg6170JPEG2025113090000007.jpg6170

[0011] The above optimization solution converts the real-time monitoring problem of the pore water pressure of the soil body at the monitoring site into the real-time monitoring problem of the groundwater level at the monitoring site. In the conventional monitoring measurement technology, the real-time monitoring means of the groundwater level can effectively utilize the richer and more diverse features than the real-time monitoring means of the pore water pressure of the soil body, and the accuracy of calculating the slope safety factor by the model of Formula 1 can be improved.

[0012] In the conventional real-time monitoring technology of groundwater level, the communicating pipe principle drainage measurement method, that is, based on the communicating pipe principle, JPEG2025113090000008.jpg17170The further optimization of the above rainfall-induced landslide monitoring and early warning method of the present invention is to provide a method for measuring the groundwater level at the monitoring site using the communicating pipe principle drainage measurement method. Specifically, the groundwater level at the monitoring site is calculated by the system of equations of Formula 3.

[0013] JPEG2025113090000009.jpg7170JPEG2025113090000010.jpg32170JPEG2025113090000011.jpg52170JPEG2025113090000012.jpg18170The monitoring data D belongs to the design parameters or operation parameters that can be determined based on background data, construction environment, equipment, and previous experiments before collecting the monitoring data.

[0014] The system of equations of Formula 3 inversely calculates the groundwater level at the underground monitoring site by using the instantaneous flow velocity when the groundwater at the underground monitoring site forms a stable water flow to the ground drain outlet. Compared with the conventional similar groundwater level measurement methods, the improvement of this method is based on long-term indoor test research data, and the independent variables of the calculation model are refined, mainly in two aspects. First, the length of the borehole is introduced as an influencing factor of the independent variable of the calculation model. Second, the head loss factor of the aqueduct is Decompose JPEG2025113090000013.jpg into two parts of 6170Ση, and make the data values obtained from the inverse calculation of the flow velocity monitoring result with respect to the groundwater level elevation more accurate and the calculation error smaller.

[0015] In the above optimization scheme, to determine the resistance coefficient λ along the conduit, there are various conventional methods, such as classical equations (Darcy - Weisbach equation, Colebrook equation), experimental methods, empirical formulas, empirical graphs, etc. The present invention further provides a scheme for measuring the resistance coefficient λ along the conduit. Specifically, it is calculated and determined by Equation 4. For JPEG2025113090000014.jpg with 5170d - take the value of the characteristic length parameter of the conduit, the inner diameter Z of the conduit (mm).

[0016] JPEG2025113090000015.jpg with 33170

[0017] It can be solved by using methods (such as the K - value method, experimental method, empirical formula, CFD simulation, etc.). However, in order to construct a measurement calculation method for the pore water pressure at the monitoring site with the complete technical logic of the communicating pipe principle drainage measurement method and improve the measurement accuracy, the present invention For JPEG2025113090000017.jpg with 28170R - the vertex turning radius of the conduit (m), α - the vertex turning angle of the conduit (°), A - the cross - sectional area of the drainage outlet (m 2 )

[0018] JPEG2025113090000018.jpg with 8170, JPEG2025113090000019.jpg with 8170, JPEG2025113090000020.jpg with 10170, JPEG2025113090000021.jpg with 13170, JPEG2025113090000022.jpg with 10170

[0019] The above optimized rainfall-induced landslide monitoring and early warning method of the present invention realizes real-time monitoring of the groundwater level and pore water pressure data at the monitoring site by using the communicating pipe principle drainage measurement method. The data monitoring and collection scheme can perform measurements if the pipeline constructed between the underground monitoring site and the ground measurement end is smooth. After filling the pipeline with water and waiting for the drainage to stabilize, there is no specific requirement for the drainage volume each time a measurement is taken, and once the flow velocity is detected, the drainage can be closed. Therefore, when adopting a high-precision micro liquid flow velocity and flow meter, an ultra-thin water conduit can be used, and the detection of the flow velocity v is extremely instantaneous and negligible with respect to the disturbance of the groundwater level and the pore water pressure of the soil mass.

[0020] Based on the above rainfall-induced landslide monitoring and early warning method, the present invention simultaneously provides a rainfall-induced landslide monitoring and early warning system, and the technical solution is as follows.

[0021] A rainfall-induced landslide monitoring and early warning system, which conducts on-site investigations of the monitored slope body S, obtains the background data of the slope body, and uses the background data of the slope body to monitor along the groundwater level line in the slope body S JPEG2025113090000023.jpg29170 Ensure that groundwater enters the water permeable cylinder, extend the water intake of the water conduit below the liquid level in the water permeable cylinder, lead the drainage outlet of the water conduit to the ground, and when the drainage at the drainage outlet stabilizes, JPEG2025113090000024.jpg5170 Determine and collect, and use the above rainfall-induced landslide monitoring and early warning method to measure the safety factor FOS(t) of the slope S at time t, and determine the safety and stability of the slope body S.

[0022] In the preferred rainfall-induced landslide monitoring and early warning method of the present invention, by collecting the dynamic flow velocity v(t) of the ground drainage outlet, the dynamic monitoring of the physical characteristics of groundwater can be completed by making use of the inverse calculation model. Therefore, the above rainfall-induced landslide monitoring and early If the 5170D of JPEG2025113090000025.jpg is monitored and collected, the FOS(t) threshold for judging the safety and stability of the slope body S is determined based on the basic data, the safety and stability model of the slope body S expressed by Equation 6 is constructed, the v threshold for judging the safety and stability of the slope body S is solved, and based on the dynamic value of the flow velocity v of the surface drainage outlet in the dynamic monitoring data D and the v threshold, the safety and stability of the slope body S is judged. In Equation 6, v(t) is the flow velocity (m / s) of the drainage outlet at time t.

[0023] Regarding the rainfall-induced landslide monitoring and early warning technology of the present invention, theoretically, when constructing the slice division method model of the slope body S, the slice division method model is detailed, JPEG2025113090000027.jpg5170 the warning accuracy is high. However, for a homogeneous slope body, for example, such a setting is likely to cause waste of technology and extend the monitoring feedback time. JPEG2025113090000028.jpg17170 it may also be co-located and matched with the same dynamic monitoring data D in the calculation. The default setting is that the monitoring JPEG2025113090000029.jpg46170 the number is determined based on the amount of data required for curve fitting.

Advantages of the Invention

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows. (1) The present invention provides a rainfall-induced landslide monitoring and early warning method based on groundwater dynamic monitoring, a method for calculating the slope safety factor using the dynamic data of the pore water pressure of the soil body at the monitoring site, and monitoring and early warning of rainfall-induced landslide disasters. (2) The technical problem that the present invention focuses on solving is to construct a technical solution that monitors and inversely calculates the key characteristic parameters of groundwater by using the flow velocity of the ground drainage outlet, with the complete technical logic of the communicating pipe principle drainage measurement method, and further calculates the slope safety factor, so as to transfer the monitoring and evaluation of the slope safety stability to the monitoring of the flow velocity of the ground drainage outlet, thereby simplifying the monitoring means and improving the monitoring accuracy. Therefore, each optimization scheme of the present invention is, JPEG2025113090000030.jpg23170 The real-time safety factor calculation method of the slope considering the real-time change of the groundwater level elevation of the present invention is to solve the real-time safety factor of the slope by calculating the static balance on each block based on the force balance and moment balance principles of the slope sliding body. This method can not only be used for sliding surfaces of any shape, but also consider the real-time change data of the pore water pressure at the bottom of the sliding surface, with short calculation time and high calculation efficiency. (4) The dynamic change of groundwater is the most crucial factor inducing rainfall-induced landslides. However, due to the lack of economical and effective groundwater dynamic monitoring means in the conventional technology, generally, rainfall and displacement, for which dynamic data are more easily obtained, are adopted as the monitoring parameters for early disaster warning, thus forming two technical types, namely the rainfall monitoring type and the displacement monitoring type, in the conventional rainfall-induced landslide monitoring and early warning scheme. The present invention utilizes the previously developed groundwater communication pipe principle drainage measurement method to solve the technical problem of inversely calculating the crucial characteristic parameters of groundwater by using the dynamic data of the ground micro-drainage flow velocity, constructs a technical solution for realizing rainfall-induced landslide monitoring and early warning based on the monitoring of the ground drainage flow velocity, and is a completely new groundwater monitoring type rainfall-induced landslide monitoring and early warning technical solution that is completely different from the conventional technical types. And the groundwater monitoring type solution of the present invention is superior to the rainfall monitoring type solution of the same period.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying out the Invention

[0026] Hereinafter, preferred embodiments of the present invention will be further described with reference to the drawings.

[0027] <Example 1> As shown in FIGS. 1 to 3, the method of the present invention is used to monitor and early warn the risk of rainfall-induced landslides on a certain slope. 1. Layout of the target slope body and monitoring instruments The slope body to be monitored is located in Quzhou City, Zhejiang Province. The overall geological structure of the landslide is relatively simple, there is a wide rainfall infiltration and recharge area at the rear edge of the slope, the permeability of the slope soil body is good, the annual change of the groundwater level is relatively large, and it is a typical rainfall-induced landslide. By adopting the technology of the present invention and monitoring the surface drainage flow velocity, the monitoring and early warning of rainfall-induced landslides occurring in this slope body are realized.

[0028] Conduct on-site investigations to obtain background data for the monitoring and early warning plan. The on-site investigations referred to in this technology include various geological investigations, surveys, surveys and mapping, measurement operations, and conventional simulation experiments, test experiments, observation experiments, analysis experiments, and acquisition of disaster histories for the slope site where the project is located, as well as relevant technical specifications, and acquisition of empirical methods and data with reference and reference functions.

[0029] FIG. 1 is a schematic layout diagram of the rainfall-induced landslide monitoring and early warning method.

[0030] Based on the background data of the monitoring plan, determine each measurement design operation parameter (Table 1).

[0031] Based on the background data of the slope body of the slope body S to be monitored, JPEG2025113090000031.jpg28170 Make it. FIG. 2 is a schematic diagram of the slice division method model of the slope body S.

[0032] In this embodiment, since the slope body to be monitored is a homogeneous soil body, JPEG2025113090000032.jpg6170Specifically, one monitoring site P is co-located with several adjacent slices, and the same dynamic monitoring data D as the design operation parameters is measured using the same part in the calculation.

[0033] JPEG2025113090000033.jpg23170Install the water-permeable cylinder 1 into the hole 4. Place the water-permeable cylinder 1 in the drilling hole to ensure that the water-permeable cylinder 1 is perpendicular to the slope surface. Extend the water conduit 2 into the water-permeable cylinder 1, and immerse the water intake 21 below the liquid level in the core layer sleeve. Pull out the drain outlet 22 of the water conduit 2 to the ground and connect the flow velocity measuring device 4. Ensure that the elevation of the water intake 21 is as large as possible compared to the elevation of the water intake 21. The inner diameter Z of the water conduit 2 is less than 5 mm. For the detailed content of the installation of each component of the device, refer to the prior art (CN 2023114987624, Method for Measuring the Elevation of the Groundwater Level, Water Storage Measurement System and Application). In this example, the flow velocity measuring device selects a high-precision micro liquid flow velocity and flow meter.

[0034] After installing the water conduit 2, perform an auxiliary water filling operation at the drain outlet 22 end. The auxiliary water filling operation may be to evacuate air at the drain outlet end to create a negative pressure, or to inject water into the pipeline from the drain outlet 2, etc. In this example, the auxiliary water filling operation is to give a certain initial pumping lift to the drain outlet 21 to initiate drainage.

[0035] 2. Monitoring Data Collection JPEG2025113090000034.jpg17170During the monitoring and early warning period, keep the water intake 21 of the water conduit 2 below the liquid level in the water-permeable cylinder 1.

[0036] To save words, only one moment t in the monitoring plan is described as a sample below. The implementation monitoring plan may be dynamic monitoring, that is, it is carried out at a plurality of consecutive moments t.

[0037] The monitoring data is shown in Table 1.

[0038] 3. Inverse Calculation This embodiment specifically implements the optimization plan of the method of the present invention, that is, all intermediate quantities are calculated and determined based on the water flow characteristics of the drainage outlet. Based on the measurement design operation parameters and the monitoring data D, the coefficient FOS(t) of the aqueduct 2 is calculated by the simultaneous equations of Equation 5 respectively. JPEG2025113090000035.jpg40170The intermediate and result calculation data are shown in Table 1.

[0039] What is shown in Table 1 are the relevant parameter data taking slice s16 and slice s17 as examples. JPEG2025113090000036.jpg17170

[0040]

Table 1

[0041] 4. Safety and Stability Evaluation of the Slope Body Based on the FOS(t) dynamic data, refer to the conventional FOS landslide risk level classification method to evaluate the degree of danger and early warning level of rainfall-induced landslides occurring in the monitored slope body S. Table 2 shows the monitoring and early warning level classification.

[0042]

Table 2

[0043] 5. Effects of Monitoring and Early Warning Technology For the slope body in this example, monitoring and early warning are carried out for half a month, and the main monitoring data are shown in Figure 3. Figure 3 shows the data curves of the three main parameters of the technology of the present invention, and at the same time, the rainfall data conditions in the same period are drawn as a contrast. Figure 3 shows that the correlation between rainfall and landslide stability is relatively poor. On the contrary, the evaluation effect of the stability state and disaster risk of the slope body by the groundwater monitoring type monitoring and early warning of the invention is superior to that of the rainfall monitoring type plan in the same period.

Description of Reference Numerals

[0044] 1 Water-permeable cylinder 2 Water conduit 21 Water intake 22 Drain outlet 3 Boring hole 4 Inclined plane 5 Landslide sliding surface 6 Inclined plane groundwater level line

Claims

1. A rainfall-induced landslide monitoring and early warning method, which acquires background data of the slope body of the slope body S to be monitored, and monitors along the groundwater level line in the slope body S Judge the safety and stability of the slope body S at time t based on FOS(t), and FOS(t) is expressed by Equation 1, In the formula, FOS(t) - is the safety factor of slope S at time t, A rainfall-induced landslide monitoring and early warning method characterized by the above.

2. The monitoring and early warning method according to Claim 1, wherein...

3. Measured by the system of equations of Equation 3, v - the flow velocity of the ground drain (22), m / s, which is dynamic monitoring data D, λ - the resistance coefficient along the road of the water conduit (2), which is a measurement design operation parameter, Z - the inner diameter of the water conduit (2), m, which is a measurement design operation parameter, η - the local head loss coefficient of the water conduit (2), which is a measurement design operation parameter, The monitoring and early warning method according to Claim 2, characterized in that...

4. The resistance coefficient λ along the road of the water conduit (2) is measured by Equation 4, △ - the absolute roughness of the material of the water conduit (2), mm, which is a measurement design operation parameter, d - the characteristic length parameter of the water conduit (2), taking the value of the inner diameter Z of the water conduit (2), mm, which is a measurement design operation parameter. The monitoring and early warning method according to Claim 3, characterized in that...

5. The local head loss coefficient Σε of the water conduit (2) is measured by the system of equations of Equation 5, R - the vertex turning radius of the water conduit (2), m, which is a measurement design operation parameter, α - the vertex turning angle of the water conduit (2), °, which is a measurement design operation parameter, A - Cross-sectional area of the drain outlet (22), m ２ , which is a measurement design operation parameter, the monitoring and early warning method according to claim 3, characterized in that.

6. A rainfall-induced landslide monitoring and early warning system, which conducts an on-site investigation of the slope body S to be monitored, acquires background data of the slope body, and uses the background data of the slope body to monitor along the groundwater elevation line in the slope body S Ensure that groundwater enters the water permeable cylinder (1), extend the water intake (21) of the water conduit (2) below the liquid level in the water permeable cylinder (1), lead the drain outlet (22) of the water conduit (2) to the ground, and when the drainage at the drain outlet (22) becomes stable, Measure and collect D, and the rainfall-induced landslide according to Claim 1 A rainfall-induced landslide monitoring and early warning system, characterized in that it uses a monitoring and early warning method to measure and calculate the safety factor FOS(t) of a slope S at time t, and judge the safety stability of the slope S.

7. For the technical proposal collected by the above method, a FOS(t) threshold value for judging the safety stability of the slope body S is determined based on basic data, a safety stability model of the slope body S expressed by Equation 6 is constructed, the v threshold value for judging the safety stability of the slope body S is solved, and the safety stability of the slope body S is judged based on the dynamic value v of the flow velocity of the ground drainage outlet (22) in the dynamic monitoring data D and the v threshold value; 7. The monitoring and early warning system according to claim 6, characterized in that, in the formula, v(t) is the flow velocity at the drain outlet (22) at time t, m / s, and D is the dynamic monitoring data.

8. A monitoring and early warning method described in any one of claims 1 to 5 or a monitoring and early warning system described in claim 6 or 7, characterized in that it matches the same dynamic monitoring data D.

9. The default setting is a monitoring system that is arranged along the groundwater level line in the slope body S. Using the groundwater dynamic elevation data, a groundwater elevation curve of the slope body S at time t is fitted; 9. The monitoring and early warning method or the monitoring and early warning system according to claim 8, further comprising: solving the groundwater elevation data obtained by the method.

10. The monitoring and early warning method according to any one of claims 1 to 5 or the monitoring and early warning system according to claim 6 or 7, characterized in that the intake (21) of the water conveyance pipe (2) is kept below the liquid level in the permeable tube (1) during the monitoring and early warning period.

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