Methods and systems for monitoring the permeability coefficient of slope soil

Abstract

This invention discloses a method and system for monitoring the permeability coefficient of slope soil. Addressing the limitation of existing technologies that can only measure the permeability coefficient of slope soil under in-situ, non-natural conditions, this invention provides a method for monitoring the permeability coefficient of slope soil. The method involves diverting groundwater from the measurement point to above-ground natural drainage, measuring the flow characteristics at the drainage outlet; utilizing the velocity and flow rate changes at the drainage outlet within the measurement range, combined with the dynamic viscosity of groundwater and the characteristic parameters of the drainage pipe structure material, to inversely calculate the groundwater elevation and permeability coefficient of the slope. An optimized scheme improves the accuracy and sensitivity of the measurement scheme by balancing undisturbed velocity measurement with enhanced water level difference through the setting of a measuring pipe and an auxiliary drainage pipe. This invention also solves the problem of calculating the dynamic viscosity of groundwater using ground ambient temperature. This invention also provides a monitoring system scheme. This invention is a novel groundwater permeability coefficient monitoring technology solution that is low-cost and low-energy.

Description

Technical Field

[0001] This invention relates to a slope monitoring and measurement technology, and in particular to a method and system for monitoring the permeability characteristics of slope soil, belonging to the fields of environmental monitoring and measurement technology and engineering geological soil monitoring and measurement technology. Background Technology

[0002] Soil permeability coefficient is an important geological parameter for slopes. In various slope safety and stability analyses, slope disaster prevention and control studies, and slope disaster monitoring and early warning technologies, the soil permeability coefficient is an almost indispensable soil characteristic parameter and forms the basis for the microscopic force balance analysis of slope soil.

[0003] There are generally two approaches to measuring soil permeability coefficients. The first approach combines on-site soil sampling with laboratory instrument analysis. This approach typically involves designing and developing various experimental measuring devices and instruments, even specialized instruments for different soil types, using precision sensors to collect relevant data. The advantages of this approach are good controllability of measurement accuracy and high accuracy of the results. The main drawback is that the process is relatively cumbersome and time-consuming; however, a more significant drawback is that the instrument measurement environment is a closed, ideal environment. The simulated environmental conditions can only be changed to a limited extent, the stress on the test soil sample is relatively stable and uniform, and the test environment always differs somewhat from the real field environment.

[0004] The second type of approach is in-situ soil measurement. The key advantage of this approach lies in the realism of the field measurement environment, effectively overcoming the shortcomings of the first type. However, existing in-situ measurement methods also have significant technical flaws. Existing technology ZL 201810501818.X discloses an in-situ soil permeability coefficient measuring device and testing method. The measuring device includes a pressure device, a pressure controller, a flow velocimeter, a measuring rod, a pressure sensor, a verticality instrument, a water tank, and a filter. The pressure controller is electrically connected to the pressure device, flow velocimeter, and pressure sensor, integrating pressure display, measurement, and control. Under the action of the pressure controller, the pressure device provides both negative and positive pressure to the measured soil through a vacuum pump or a pressure pump, suitable for sandy and clay soils. The main technical flaws of this technology are: firstly, the measurement process requires the construction of a specific measurement platform, and the pressure pump continuously provides positive pressure during the measurement process, under which various data are read. In other words, although the measurement is carried out "in situ," the soil being measured is actually a localized soil mass under constant human control. The measurement process is "in situ" but "unnatural," causing in-situ measurement to lose its most important technical value. Secondly, the existing pumping and filling processes involve large volumes of water and require additional dynamic conditions, resulting in additional energy consumption. Furthermore, the process involves numerous measurement parameters and is complex, making it prone to measurement errors. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a slope soil permeability coefficient measurement technology that enables in-situ and natural measurement in the field.

[0006] To achieve the above objectives, the present invention first provides a method for monitoring the permeability coefficient of slope soil, the technical solution of which is as follows.

[0007] A method for monitoring the permeability coefficient of slope soil, characterized by: determining the underground measurement point P, setting the measurement interval T, and the start and end times of T being respectively... , The monitoring data D, which measures the characteristics of groundwater at point P, includes time data. With time groundwater elevation and ,time The flow rate W at the surface drainage outlet was measured; the groundwater characteristic data D at point P was measured using the communicating vessel principle drainage measurement method, and the flow movement characteristic index at the drainage outlet was used to calculate the flow rate W. A method for measuring groundwater level characteristics, the aforementioned communicating vessel principle drainage measurement method is based on the communicating vessel principle, using a water guide pipe to measure the groundwater level at a point. The permeable pipe draws groundwater to the surface for drainage, and the flow characteristics of the drainage outlet are used to calculate the back-calculation. Methods for measuring groundwater level characteristics; calculate the soil permeability coefficient k at point P according to Equation 1.

[0008] Formula 1

[0009] In the formula, k is the soil permeability coefficient at the underground measurement site, in m / s.

[0010] W-moment The flow rate of the drain outlet, m 3 / s, determined based on monitoring data D.

[0011] R – Radius of influence, in meters, determined by the measurement design operating parameters.

[0012] - Drilling radius, in meters, determined according to the measurement design operating parameters.

[0013] and Point P is at and The groundwater elevation, in meters, is determined based on monitoring data D.

[0014] - Borehole elevation, in meters, determined according to the surveying and design operating parameters.

[0015] b – Drilling length, in meters, determined according to the measurement design operating parameters.

[0016] The aforementioned method for monitoring the permeability coefficient of slope soil is based on the principle of energy balance in fluid flow in communicating vessels. Groundwater is brought above ground, and the soil permeability coefficient at the underground monitoring site is retrieved by monitoring the flow parameters at the surface drainage outlet. Based on previous research, the data foundation for the inversion calculation model includes borehole data and groundwater variation parameters at the measurement time: firstly, surface drainage outlet flow monitoring data (flow rate W); and secondly, groundwater level monitoring data (elevation). and Elevation and It can be measured using existing technologies (e.g., CN 2023114987624, Groundwater Level Elevation Measurement Method, Water Storage Measurement System and Application).

[0017] This invention optimizes the aforementioned monitoring method based on previous research data. Specifically, based on Darcy's law, an inversion calculation model is directly constructed between the flow velocity monitored at the drainage outlet and the soil permeability coefficient parameter at the measurement site. Simultaneously, the dynamic viscosity of groundwater is incorporated into the inversion calculation model to ensure that the influence of groundwater fluid properties on the flow velocity at the drainage outlet can be measured and reflected by the calculation model. The groundwater elevation a at point P at time t is calculated according to Equation 2.

[0018] Formula 2

[0019] In the formula, a – groundwater elevation at point P at time t (m), v – flow velocity at the surface drainage outlet at time t (m / s), μ – dynamic viscosity of groundwater (Pa·s), L – length of the drainage pipe (m), ρ – density of groundwater (g / cm³). 3 c - hydraulic radius of the water pipe (m). - Drainage outlet elevation (m), g - acceleration due to gravity ( ).

[0020] In the above optimization scheme, the dynamic viscosity μ of groundwater can be determined using existing technologies, such as experimental measurement or direct consultation of experience manuals. To establish a consistent technical solution, this invention further optimizes the process by addressing the technical problem of calculating the dynamic viscosity μ of groundwater using flow velocity monitoring at drainage outlets. The dynamic viscosity μ of groundwater is calculated according to Equation 3.

[0021] Equation 3-1

[0022] Equation 3-2

[0023] In the formula, f is the kinematic viscosity of groundwater (m³). 2 / s), e—ground ambient temperature (°C).

[0024] The optimization scheme for the above-mentioned slope soil permeability coefficient monitoring method, in addition to the aforementioned optimization of the inversion calculation, also includes the following optimizations of the monitoring operation conditions. These optimizations are not required to be implemented simultaneously.

[0025] Optimization 1: Within the measurement interval T, the ground drain outlet of the measuring device maintains a stable water flow, with T being 8h to 24h.

[0026] Optimization 2: After the water pipe is installed, an auxiliary water filling operation is performed at the drainage outlet to fill the pipe and guide the drainage. In slope groundwater monitoring, the free face of the slope is usually used to ensure the drainage outlet is lower than the inlet, creating a certain elevation difference. Therefore, after the drainage outlet begins to drain, the drainage process can proceed spontaneously and stably without any additional energy consumption from pumping or filling. The auxiliary water filling operation can be achieved by creating negative pressure by evacuating air at the drainage outlet or by reverse-flowing water from the drainage outlet into the pipe.

[0027] Optimization 3: Insert N water-conducting pipes into the permeable cylinder, where N ≥ 2. The inlets of the N pipes are at the same point below the liquid level inside the permeable cylinder, and the outlets are at the same elevation on the ground. One of the N pipes is a measuring pipe, and the rest are auxiliary drainage pipes. The groundwater characteristic monitoring data D at point P is measured and collected from the outlet of the measuring pipe. This optimization ensures that the measurement of the groundwater elevation a can be completed at time t based on the instantaneous outflow velocity of the extremely fine drainage outlet, and also improves the accuracy of monitoring data within the measurement interval T. to The rate of change makes the underwater changes more obvious and easier to capture, thereby improving the sensitivity and accuracy of the monitoring scheme in two ways. N water pipes are of the same specification. For different slope soil types, a more optimal design for the number of water pipes is: if the slope soil is clay, N = 3–7; if the slope soil is silt, N = 7–13; if the slope soil is sand, N = 16–24.

[0028] Optimization 4: Drill holes and permeable pipes should be installed perpendicular to the slope surface.

[0029] Optimization 5: The conical permeable stone at the end of the permeable core casing is kept in a single underground aquifer, and the inner diameter of the water conduit is less than 5mm.

[0030] Based on the slope soil permeability coefficient monitoring method of the present invention, the present invention also provides a groundwater storage monitoring and measurement system, the technical solution of which is as follows.

[0031] A slope soil permeability coefficient monitoring system is characterized by: setting a slope soil permeability coefficient measurement point P, drilling a hole at point P and inserting a permeable cylinder to ensure that groundwater enters the permeable cylinder, with the inlet of a water guide pipe extending below the liquid surface inside the permeable cylinder, and the outlet of the water guide pipe leading to the ground surface; after the outlet stabilizes and water flows out, measuring and collecting monitoring data D of the groundwater characteristics at point P; and using the monitoring data D and the measurement design operation parameters to calculate the soil permeability coefficient k at point P.

[0032] Compared with the prior art, the beneficial effects of the present invention are: (1) The preliminary research of the present invention found that by constructing a water flow pipeline between the underground borehole measurement site and the ground monitoring site using a water guide pipe, based on the principle of liquid flow energy balance, the flow velocity of the ground drainage outlet of the pipeline can characterize the groundwater level elevation characteristics of the borehole. The technical solution of the present invention extends this research finding by introducing a measurement time parameter characterized by the measurement interval, calculating the groundwater elevation data at a specified time (i.e., at both ends of the measurement interval), and introducing the drainage outlet flow parameter into the groundwater infiltration characteristic inversion calculation model; at the same time, by utilizing the free surface characteristics of the slope topography, the measurement process is achieved without additional energy consumption. Thus, the present invention provides a technical solution for monitoring the groundwater permeability coefficient completely in situ at the measurement site and under fully natural environmental conditions. It specifically overcomes the technical defects of the existing in-situ monitoring technology of "in situ rather than natural", and is a brand-new concept for groundwater permeability coefficient monitoring technology. (2) This invention further incorporates Darcy's law of groundwater seepage within the soil, integrating the dynamic viscosity of groundwater and the structural / material characteristics of the drainage pipe into the groundwater elevation calculation model defined by the flow velocity at the drainage outlet. This improves the overall accuracy of the groundwater elevation calculation model using the flow velocity at the drainage outlet, and also enhances the accuracy of the groundwater permeability coefficient monitoring technology of this invention. (3) In the technical concept of this invention, when using the communicating vessel principle drainage measurement method to invert the groundwater elevation characteristics of the groundwater location using the flow velocity at the surface drainage outlet, the preferred solution is to use an extremely fine drainage pipe in conjunction with a high-precision micro-liquid velocity meter to instantly complete the flow velocity detection at the drainage outlet, ensuring that only a negligible, extremely small disturbance is generated to the groundwater level elevation. However, in the overall groundwater permeability coefficient monitoring scheme, the ideal state is that there is a significant elevation difference between the groundwater elevations at two specified times, thereby amplifying the groundwater permeability characteristics and making them easier to capture and monitor. To specifically address this contradiction, this invention improves the drainage pipe design, sets up multiple drainage pipes, and distinguishes between the measuring pipe and the auxiliary drainage pipe. Thus, the measuring tube can adopt the design of a fine-diameter water pipe + a small flow meter to improve the accuracy of flow velocity acquisition; the drainage pipe can realize parallel drainage of multiple pipes, accelerate the rate of elevation change, and form a more obvious elevation difference. On this basis, further limiting all water pipes to the same specification can reduce the impact of the siphon effect of the drainage pipe on the water surface disturbance in the permeable tube on the water inlet of the measuring tube. The optimized scheme takes into account the accuracy and sensitivity of the monitoring scheme in both local and overall aspects, and enhances the technical value of in-situ monitoring schemes for groundwater permeability coefficient. (4) The equipment and implementation of this invention have the characteristics of low cost and low energy consumption, and are suitable for slope disaster prevention schemes in various mountainous areas. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the layout of the slope soil permeability coefficient monitoring method.

[0034] The numbers in the attached diagram are labeled as follows:

[0035] 1. Permeable cylinder; 2. Water conduit; 21. Inlet; 22. Outlet; 3. Borehole; 4. Slope; 5. Initial groundwater level. Detailed Implementation

[0036] The preferred embodiments of the present invention will now be further described with reference to the accompanying drawings.

[0037] Example 1

[0038] like Figure 1 As shown, the method of the present invention is used to monitor the permeability coefficient of a slope soil.

[0039] 1. Layout of the target slope and monitoring instruments

[0040] The monitored slope is located in Jiangshan City, Zhejiang Province. The geological structure of the landslide is simple, with a relatively 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. The slope permeability coefficient is closely related to the slope's safety and stability. This invention is used to monitor the soil permeability coefficient of this slope.

[0041] Conduct on-site investigations to obtain baseline data for the monitoring 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.

[0042] Schematic diagram of the layout of slope soil permeability coefficient monitoring method.

[0043] To save space, the following description uses only one set of monitoring intervals T from the monitoring plan as an example. The monitoring plan can be implemented dynamically, that is, across multiple consecutive monitoring intervals T.

[0044] Based on the baseline data from the monitoring plan, the operational parameters for each measurement design were determined (Table 1). Existing technologies offer various methods for calculating the radius of influence R. This specific implementation method uses a method that determines R based on two parameters: unit outflow and unit water level drop, as detailed in Table 2.

[0045] Based on the baseline data, the underground measurement point P within the slope body is determined, and the vertical projection point P′ of point P onto the slope surface is determined. A borehole 3 is drilled perpendicularly to the slope surface at point P′, to a depth below the groundwater level, with a length b. A permeable cylinder 1 is installed inside the borehole.

[0046] 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 water guide pipe 2 to the outlet 22 above ground level and connect it to the flow velocity meter. The conical permeable stone at the end of the core casing of the permeable cylinder 1 remains within a single underground aquifer. For detailed installation instructions of each component, refer to existing technology (CN 2023114987624, Groundwater Level Elevation Measurement Method, Water Storage Capacity Measurement System and Application). In this example, a high-precision micro liquid flow meter is selected as the flow velocity meter.

[0047] After the water pipe 2 is installed, an auxiliary filling water operation is performed at the drain outlet 22. In this example, the auxiliary filling water operation involves giving the drain outlet 22 a certain amount of initial pumping water to guide the start of drainage.

[0048] 2. Monitoring data collection

[0049] Define the measurement interval T, where the start and end times of T are respectively... , The monitoring data D, which measures the characteristics of groundwater at point P, includes the time interval. With time Drainage outlet 22 flow rate and ,time The flow rate W at drain outlet 22 is maintained. The water flow from drain outlet 22 is kept stable within the measurement interval T.

[0050] The monitoring data is shown in Table 1.

[0051] 3. Inversion Calculation

[0052] This embodiment specifically implements the optimized scheme of the measurement method of the present invention, that is, all intermediate quantities are calculated and determined based on the dynamic characteristics of the drainage outlet water flow. Based on the measurement design operation parameters and monitoring data D, the following are performed sequentially: the kinematic viscosity f and the dynamic viscosity μ of the groundwater are calculated according to Equation 3, and the groundwater at point P at time is calculated according to Equation 2. and elevation and The soil permeability coefficient k at point P is calculated according to Equation 1. Intermediate and final calculation data are shown in Table 1. Note that since there are N = 10 water pipes 2 in the design, the time... The flow rate W at the drain outlet 22 is the total flow rate of all N water pipes 2.

[0053] Table 1 Relevant parameter data

[0054]

[0055] Table 2 Empirical values ​​of influence radius R

[0056]

Claims

1. A method for monitoring the permeability coefficient of slope soil, characterized in that: Determine the underground measurement point P, and set the measurement interval T, with the start and end times of T being respectively... , The monitoring data D, which measures the characteristics of groundwater at point P, includes time data. With time groundwater elevation and ,time Flow rate W of the ground drainage outlet; The groundwater characteristic data D at point P was measured using the drainage measurement method based on the principle of communicating vessels, and the flow movement characteristic index at the drainage outlet was used to calculate the groundwater characteristic data D. Groundwater level characteristics, the aforementioned communicating vessel principle drainage measurement method is based on the communicating vessel principle, using a water guide pipe to measure the point Groundwater is drawn to the surface through a permeable pipe inside the borehole for drainage, and the flow characteristics of the drainage outlet are used to calculate... Groundwater level characteristics; calculate the soil permeability coefficient k at point P according to Equation 1. Formula 1 In the formula, k is the soil permeability coefficient at the underground measurement site, in m / s. W-moment The flow rate of the drain outlet, m 3 / s, determined based on monitoring data D. R – Radius of influence, in meters, determined by the measurement design operating parameters. - Drilling radius, in meters, determined according to the measurement design operating parameters. and Point P is at and The groundwater elevation, in meters, is determined based on monitoring data D. - Borehole elevation, in meters, determined according to the surveying and design operating parameters. b – Drilling length, in meters, determined according to the measurement design operating parameters.

2. The monitoring method according to claim 1, characterized in that: The groundwater elevation 'a' at point P at time t is calculated according to Equation 2. Formula 2 In the formula, a – the groundwater elevation of point P at t, in meters. v – the flow velocity at the surface drainage outlet at time t, in m / s, determined based on monitoring data D. μ – Dynamic viscosity of groundwater, Pa·s, determined according to the measurement design operating parameters. L – Length of the water pipe, in meters, determined based on the measured design operating parameters. p - density of groundwater, g / cm 3 , depending on the measurement design operating parameters, c – Hydraulic radius of the water pipe, in meters, determined based on measurement, design, and operating parameters. - Drainage outlet elevation, in meters, determined based on surveying and design parameters. g — acceleration due to gravity ,constant.

3. The monitoring method according to claim 2, characterized in that: The dynamic viscosity μ of the groundwater is calculated according to Equation 3. Equation 3-1 Equation 3-2 In the formula, f represents the kinematic viscosity of groundwater, m 2 / s, e—Ground ambient temperature, °C, determined according to the measurement design operating parameters.

4. The monitoring method according to any one of claims 1 to 3, characterized in that: Within the measurement interval T, the ground drain outlet of the measuring device maintains a stable water discharge, with T ranging from 8h to 24h.

5. The monitoring method according to claim 4, characterized in that: After the water pipe is installed, an auxiliary water filling operation is performed at the drain outlet to fill the water pipe with water and guide the drain outlet to drain water.

6. The monitoring method according to claim 4, characterized in that: N water pipes are inserted into the permeable cylinder, where N≥2. The inlets of the N water pipes are at the same point below the liquid level inside the permeable cylinder, and the outlets are at the same elevation on the ground. One of the N water pipes is a measuring pipe, and the rest are auxiliary drainage pipes. The monitoring data D of the groundwater characteristics at point P is measured and collected from the outlet of the measuring pipe. The N water pipes are of the same specification.

7. The monitoring method according to claim 6, characterized in that: If the slope soil is clay, N = 3-7; if the slope soil is silt, N = 7-13; if the slope soil is sand, N = 16-24.

8. The monitoring method according to claim 4, characterized in that: The boreholes and permeable pipes are installed perpendicular to the slope surface.

9. According to the monitoring method of claim 4, the conical permeable stone at the end of the permeable core sleeve is kept in a single underground aquifer, and the inner diameter of the water conduit is less than 5 mm.

10. A slope soil permeability monitoring system implemented using any one of the slope soil permeability monitoring methods described in claims 1 to 9, characterized in that: Set a measurement point P for the permeability coefficient of the slope soil, drill a hole at point P and insert a permeable cylinder to ensure that groundwater enters the permeable cylinder. The inlet of the water pipe extends below the liquid level inside the permeable cylinder, and the outlet of the water pipe leads to the ground. Once the drainage outlet is stabilizing and water is flowing out, measure and collect monitoring data D of the groundwater characteristics at point P; use the monitoring data D and the measurement design operation parameters to calculate the soil permeability coefficient k at point P.

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