CN104406623A - Method for determining dynamic stability coefficient of side slope based on underground water level and displacement monitoring - Google Patents

Abstract

The invention discloses a method and technology for measuring the dynamic stability coefficient of this type of slope based on the groundwater level change and displacement monitoring data, coupling and crossing the cause and mechanism of landslide formation with the change of displacement response information and its evaluation method, through Establish a nonlinear unloading load-response ratio parameter prediction model and then establish a slope stability coefficient measurement method based on groundwater level and displacement changes. This landslide displacement prediction method has changed the traditional displacement time-series prediction method that only selects landslide displacement or displacement rate as monitoring. Based on the idea of evaluating parameters, it is proposed to monitor and integrate the landslide groundwater level and displacement or displacement rate at the same time, so as to determine the coupled integrated dynamic prediction parameters and evaluation method of landslide groundwater level and displacement or displacement rate; this method can not only overcome the static limit The limitation that the mechanical evaluation method cannot analyze and evaluate the change law of slope stability over time, and at the same time, it can overcome the disadvantages that the traditional displacement time series prediction method cannot analyze and evaluate the formation mechanism and motivation of landslides.

Description

Method for Determination of Dynamic Stability Coefficient of Slope Based on Groundwater Level and Displacement Monitoring

technical field

The invention belongs to the field of quantitative evaluation and prevention of water-induced landslide dynamic stability, and in particular relates to a method and technology for measuring the dynamic stability coefficient of this type of slope based on groundwater level change and displacement monitoring data. the

Background technique

Landslides are an important research content in the field of natural disasters and environmental science. From the perspective of geological disasters, landslides are common and frequently occurring, widely distributed and extremely harmful geological disasters, which often threaten national economic construction and people's lives and property. All brought huge losses. As we all know, the change of groundwater environment is the most important formation mechanism and cause of landslides. According to statistics, landslides induced by changes in the groundwater environment caused by rainfall account for 70% of the total number of landslides. In recent years, with the development of water conservancy projects, especially the construction and water storage of the Three Gorges Project on the Yangtze River, landslides caused by changes in the reservoir water level caused by changes in the groundwater environment have also attracted much attention. Therefore, how to scientifically and effectively induce landslides for such water Accurate stability evaluation and early warning of slope will have important scientific significance and engineering application value. the

The core issues of slope stability evaluation are the selection of evaluation methods and the determination of stability criteria. At present, in slope stability evaluation and landslide geological disaster monitoring, early warning and prevention methods, the most widely used prediction and evaluation methods are limit equilibrium mechanics evaluation method and displacement time series prediction method. The limit equilibrium evaluation method is a mechanical evaluation model based on the clear and definite mechanism of slope instability and stress conditions. Or greater than 1 to judge whether the slope is stable or not. However, the model established by the limit equilibrium evaluation method is a static evaluation model without time parameters, and this type of method needs to first accurately determine various physical and mechanical parameters and slip boundary conditions, so the static evaluation method cannot be used for the stability of rainfall landslides. In addition, in slope stability evaluation, especially in the slope stability evaluation of large complex slope structure and material composition, it is necessary to accurately measure these physical and mechanical parameters and slip boundary conditions. It is very difficult, or impossible to do it at all, so it is easy to distort the evaluation results or cause misjudgment. Compared with the limit equilibrium evaluation method, the displacement time series prediction method is based on the monitoring of landslide displacement, and uses displacement parameters (displacement, displacement rate, displacement acceleration rate) and their changes as the prediction parameters and evaluation criteria for slope stability and stability. . Its displacement (deformation) monitoring has the advantages of high precision, easy implementation, and comprehensive and intuitive reflection of the slope stability state. Therefore, this type of method overcomes the shortcomings and limitations of the limit equilibrium mechanics method to a certain extent, and has been used in major projects in my country. Landslide areas are widely used and play an important role. However, the displacement time-series prediction method reflects the trend and law of landslide deformation over time, and most of them are displacement apparent mathematical evaluation models based on mathematical statistics. The formation mechanism and mechanical dynamics of the deformation and instability of the landslide are unknown, and there is no stable and unified instability criterion. Although there are successful monitoring cases, because the law obtained by time series analysis is not based on the mechanism, the prediction results often have Great probability. the

Contents of the invention

In order to overcome the above-mentioned problems existing in the prior art, the object of the present invention is to provide a method for determining the dynamic stability coefficient of a slope based on groundwater level and displacement monitoring. In order to determine and establish the coupled integrated dynamic prediction parameters of landslide groundwater level and displacement or displacement rate, and use the basic principles of damage mechanics to find the quantitative relationship between the dynamic prediction parameters and the stability coefficient in the traditional stability evaluation method. the

A kind of slope dynamic stability coefficient determination method based on groundwater level and displacement monitoring provided by the invention, it comprises the following concrete steps:

(1) Monitor the basic data of slope groundwater level and displacement

① Monitoring instruments: groundwater level monitoring equipment: a, pressure water level gauge, b, air pressure compensation device; slope displacement monitoring equipment: wireless GPS displacement monitoring equipment (see Figure 2);

② Arrange monitoring points on the main sliding surface of the monitoring slope corresponding to the slope surface, and arrange N monitoring points for slope displacement changes at equal distances from the trailing edge rupture wall to the leading edge shear outlet slope according to the actual terrain of the slope surface, where N is greater than Or an integer equal to 1; Displacement monitoring reference points shall be arranged in stable bedrock or non-deformed areas outside the monitoring landslide mass, no less than 3 to form a control network;

③Groundwater level monitoring method: Drill holes at the selected monitoring points on the slope. The depth of the drill holes should reach the bedrock surface or below the groundwater level in previous years. Additional air pressure compensation device to jointly monitor the change of groundwater level;

④Slope displacement monitoring method: Arrange wireless GPS displacement monitoring equipment at the positions of displacement monitoring reference points and slope drilling monitoring points; ensure that the buried slope displacement change monitoring equipment is closely integrated with the surface of the landslide body, and the monitoring points are monitored horizontally and vertically. Monitor the displacement change value;

⑤Real-time monitoring of the groundwater level and displacement of the landslide with a certain time interval accuracy, and record the monitoring data of the groundwater level and displacement at the same time, and transmit the monitoring data to the remote monitoring room through the slope site data signal collector, and classify and preprocess the monitoring data . the

(2) Determination of landslide groundwater dynamic unloading parameters and displacement response parameters

① Determination of groundwater level unloading parameters

According to the monitoring data, the statistical analysis and prediction cycle of the landslide is determined, and based on the statistical analysis and prediction cycle, the difference ΔH between the groundwater level H _i of the landslide in a certain month and the ground water level H _i-1 of the previous month is calculated:

ΔH＝H _i -Hi _-1 formula (1)

ΔH in formula (1) is used as the standard of hydrodynamic unloading load. When ΔH > 0, it is determined that the landslide is loaded; when ΔH < 0, it is determined that the landslide is unloaded; the ΔH is counted according to the positive and negative values of the unloading load of each unloading cycle, and the average value can be obtained respectively. Groundwater table unloading parameters for the unloading sequence and.

②Determination of displacement and unloading response parameters

In the unit statistical analysis and prediction cycle, the unloading displacement response parameters of the landslide are based on the displacement acceleration a equal to zero, the value less than zero is the unloading response value, and the value greater than zero is the loading response value. The positive and negative values of the loading response are counted and averaged, and the average value of the displacement acceleration response of the unloading sequence can be obtained and

(3) Determination of the parameters of the landslide groundwater dynamic unloading load-displacement response ratio

① Determination of response rate of landslide unloading

Based on modern nonlinear scientific theory, the mean value of slope displacement acceleration unloading response The corresponding groundwater level unloading average The ratio is determined as the slope dynamic unloading displacement response rate χ _- , and the mean value of the slope displacement acceleration loading response The corresponding groundwater table loading mean The ratio of is determined as the slope dynamic loading displacement response rate χ ₊ , namely:

${\mathrm{\&chi;}}_{-}=\frac{{\mathrm{\&Delta;R}}_{-}}{\mathrm{\&Delta;}{m}_{-}}=\frac{{\stackrel{\&OverBar;}{a}}_{-}}{{\stackrel{\&OverBar;}{\mathrm{\&Delta;H}}}_{-}}$ Formula (2)

${\mathrm{\&chi;}}_{+}=\frac{{\mathrm{\&Delta;R}}_{+}}{\mathrm{\&Delta;}{m}_{+}}=\frac{{\stackrel{\&OverBar;}{a}}_{+}}{{\stackrel{\&OverBar;}{\mathrm{\&Delta;H}}}_{+}}$ Formula (3)

② Determination of the parameters of the landslide groundwater dynamic unloading load-displacement response ratio

According to formula (2) and formula (3) and the definition of unloading load-response ratio, the parameters of slope groundwater level dynamic unloading-displacement response ratio can be determined as:

$\mathrm{\&gamma;}=\frac{{\mathrm{\&chi;}}_{-}}{{\mathrm{\&chi;}}_{+}}=\left(\frac{\mathrm{\&Delta;}{R}_{-}}{\mathrm{\&Delta;}{m}_{-}}\right)/\left(\frac{\mathrm{\&Delta;}{R}_{+}}{\mathrm{\&Delta;}{m}_{+}}\right)=\left(\frac{{\stackrel{\&OverBar;}{a}}_{-}}{{\stackrel{\&OverBar;}{\mathrm{\&Delta;H}}}_{-}}\right)/\left(\frac{{\stackrel{\&OverBar;}{a}}_{+}}{{\stackrel{\&OverBar;}{\mathrm{\&Delta;H}}}_{+}}\right)$ Formula (4)

(4) Determination of dynamic stability coefficient of water-induced landslide

① Determination of the quantitative relationship between slope damage variables and unloading load response ratio parameters

According to principle of the present invention (2), the quantitative relation of its damage variable D and unloading load-response ratio parameter is as follows:

D _t = 1-γ _t formula (5)

Formula (5) shows that there is a one-to-one quantitative relationship between the unloading load response ratio γ of rock and soil materials and its damage variable D. the

② Determination of dynamic stability coefficient of water-induced landslide

Quantitative relationship between damage variables and stability coefficient determined by limit equilibrium evaluation method in slope engineering and the formula

(5) The dynamic stability coefficient of water-induced landslide can be determined as:

$f_t=\frac{1}{1-{\mathrm{\&gamma;}}_t}$ Formula (6)

Equation (6) shows that there is a one-to-one correspondence between the unloading load response ratio and the slope stability coefficient. the

(5) Determination of early warning criteria for water-induced landslide instability

In the actual work of landslide prevention and engineering investigation and design, a safety reserve is usually set for the stability factor to obtain a safety factor K as the criterion of its stability. According to the importance of slope stability and the complexity of slope geological conditions, as well as the "Code for Geological Hazard Prevention Engineering Survey" (DB50/143-2003) and "Code for Slope Design of Water Conservancy and Hydropower Engineering" (SL386-2007), it can be integrated Determine the slope stability safety factor K, such as K=1.3, 1.25, 1.15, etc.; by comparing the dynamic stability factor F _t of the slope determined in the above steps with the traditional safety factor K, the water-induced type can be quickly and accurately The dynamic early warning evaluation and treatment design of the slope stability, that is, when F _t ≥ K, the slope is in a stable state; when F _t ≤ k, the slope is in an unstable state.

Basic principle of the present invention is as follows:

1. Definition of unloading load-response ratio parameters

Modern nonlinear scientific theory holds that the same thing, at different stages of development and evolution, responds differently to external disturbances. If the various external factors that may be encountered during the development and evolution of the landslide, such as rainfall, reservoir water level changes, and human engineering activities, are commonly referred to as generalized loads, and M is used to represent them; the response of the slope after being subjected to generalized loads (such as Displacement, strain, acoustic emission and other state variables) are defined as R, and the relationship between generalized load and system response is shown in Figure 3. When the load increment is ΔM, the corresponding response increment is ΔR, and the response rate χ is defined as:

$\mathrm{\&chi;}=\underset{\mathrm{\&Delta;M}\&Right\; Arrow;0}{\lim }\frac{\mathrm{\&Delta;R}}{\mathrm{\&Delta;M}}$ Formula (7)

Let χ _- and χ ₊ denote unloading and loading response rates, respectively. When the load is very small, the system is in a stable state. At this time, the relationship between R and M is linear or approximately linear, and the response rate χ ₊ during loading is basically equal to the response rate _χ- during unloading; if the load continues to increase, it will gradually approach the critical Value Mcr, that is, when the system tends to be unstable, its response rate increases continuously with the increase of load; when the system is unstable, X _+→∞ . This shows that when the system is on the verge of instability, even a very small load will cause the system to respond violently. Therefore, even if the load increment remains unchanged, the response rate of the nonlinear system will vary greatly due to the different stable states of the system. The greater the response rate, the closer the system is to instability. In order to find out more general rules, define the unloading load-response ratio:

$\mathrm{\&gamma;}=\frac{{\mathrm{\&chi;}}_{-}}{{\mathrm{\&chi;}}_{+}}=\underset{\mathrm{\&Delta;M}\&Right\; Arrow;0}{\lim }\left(\frac{{\mathrm{\&Delta;R}}_{-}}{{\mathrm{\&Delta;M}}_{-}}\right)/\left(\frac{{\mathrm{\&Delta;R}}_{+}}{{\mathrm{\&Delta;M}}_{+}}\right)$ Formula (8)

In the formula: ΔR _- and ΔR ₊ are unloading response increments and loading response increments, respectively; ΔM _- and ΔM ₊ are unloading increments and loading increments, respectively. For an elastic system, χ ₊ ＝χ _- ＝c, so γ=1; but for a nonlinear system, the value of γ varies with the stable state of the system. When the system is in a stable state, γ=1; when the system deviates from the steady state, γ<1; when the system is unstable, γ→0. Therefore, the γ value can quantitatively describe the degree of stability of the nonlinear system, and can also be used as a criterion for predicting the instability of the nonlinear system.

2. Quantitative relationship between damage variable and unloading load response ratio parameter From the perspective of damage mechanics, the breeding process of landslide is the damage evolution process of slope material. In damage mechanics, the damage process and damage degree can be quantitatively described and described by using the damage variable D, which is defined as the change rate of the deformation modulus E of the material, namely:

$\mathrm{D.}=\frac{{\mathrm{E.}}_o-\mathrm{E.}}{{\mathrm{E.}}_o}=1-\frac{\mathrm{E.}}{{\mathrm{E.}}_o}$ Formula (9)

In the formula, _E0 is the modulus of the initial state (undamaged), and E is the modulus of damage. When the material is not damaged, E=E ₀ , D=0; when the material is completely destroyed, E=0, D=1.

The unloading load response ratio used in the present invention is the ratio of the ratio of strain and stress of the slope body in the unloading stage to the ratio of strain and stress of the slope body in the loading stage. Right now

$\mathrm{<span\; class="notranslate">\; \&gamma;</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&Delta;\&epsiv;</span>}}_{<span\; class="notranslate">\; -</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; \&Delta;\&sigma;</span>}}_{<span\; class="notranslate">\; -</span>}}{{\mathrm{<span\; class="notranslate">\; \&Delta;\&epsiv;</span>}}_{<span\; class="notranslate">\; +</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; \&Delta;\&sigma;</span>}}_{<span\; class="notranslate">\; +</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{<span\; class="notranslate">\; -</span>}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; E.</span>}}_{<span\; class="notranslate">\; +</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; E.</span>}}_{<span\; class="notranslate">\; +</span>}}{{\mathrm{<span\; class="notranslate">\; E.</span>}}_{<span\; class="notranslate">\; -</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

Considering that the modulus of the material when it is unloaded is generally approximately equal to the initial elastic modulus E ₀ , that is, E _- =E ₀ , and E ₊ =E, then:

$\mathrm{D.}=1-\frac{\mathrm{E.}}{{\mathrm{E.}}_0}=1-\mathrm{\&gamma;}$ Formula (11)

When γ=1, D=0; indicating that the material is not damaged and in a stable state; when γ→0, D=1; indicating that the material is completely damaged. the

3. Quantitative relationship between damage variable and stability coefficient The shear failure of slope rock and soil is essentially the final form of the structural damage of rock and soil that leads to the change of its mechanical properties. In the study of the damage process of slope rock and soil Shear strength is a sensitive and easily measured factor. When part of the rock-soil mass reaches its shear strength, partial failure occurs and the overall performance is stable; when the rock-soil mass of the slope fully reaches its shear strength, the slope body is completely destroyed. Therefore, the damage variable D can be defined in the sense of rock and soil strength failure, which is the failure probability when the shear stress of the rock and soil on the potential slip surface of the slope is greater than the shear strength, which describes the failure of the slope rock and soil degree. In the evaluation of slope stability limit equilibrium method, the stability coefficient is usually defined as the ratio of the anti-sliding force on the potential slip surface of the slope to the sliding force, which describes the degree of stability of the slope. Therefore, in slope engineering, the slope stability coefficient can be defined as the ratio of the limit damage variable D _lim to the slope damage variable D _t at any time, namely:

$f_t=\frac{{\mathrm{D.}}_{\lim }}{{\mathrm{D.}}_t}$ Formula (12)

In formula (12): D _t is the damage variable at time t, D _lim is the limit damage variable and takes 1.

A method for determining the dynamic stability coefficient of a slope based on groundwater level and displacement monitoring provided by the present invention has the beneficial effect of organically coupling the change in groundwater level of the landslide with the change in the response information of the landslide displacement and its evaluation method, which is effective and reasonable The dynamic stability coefficient of the slope is accurately determined, and based on this, the evolution law of the dynamic stability of the slope can be reasonably analyzed and evaluated, which overcomes the difficulty of accurately determining the physical and mechanical parameters and boundary conditions of the landslide by the traditional limit equilibrium mechanics evaluation method At the same time, it solves the problems that the traditional displacement time series prediction method cannot quantitatively describe the dynamic mechanism of the landslide and has no stable and unified instability criterion. the

Description of drawings

Fig. 1 is a determination flow chart of slope dynamic stability coefficient of the present invention;

Fig. 2 is the schematic diagram of slope groundwater and displacement monitoring points and monitoring collection and processing equipment of the present invention, wherein 1 is a pressure water level gauge, 2 is an air pressure compensation device, 3 is a displacement monitoring point, 4 is a displacement change monitoring device, and 5 is a monitoring Reference points and equipment, 6 is the data acquisition equipment, 7 is the remote monitoring room;

Fig. 3 is the relation diagram of generalized load and system response in the slope evolution process of the present invention;

Fig. 4 is a certain side slope and monitoring point schematic diagram thereof of the embodiment of the present invention;

Fig. 5 is a certain side slope F point unloading load-response ratio curve figure of the embodiment of the present invention;

Fig. 6 is a curve diagram of the stability coefficient of point F of a certain slope according to an embodiment of the present invention. the

Detailed ways

Referring to the accompanying drawings, the method for determining the dynamic stability coefficient of a slope based on groundwater level and displacement monitoring provided by the present invention will be described in detail below in conjunction with embodiments. the

Example

In order to better illustrate the present invention, a water-induced accumulative landslide will ^be taken as an example in further detail below in conjunction with the ^accompanying drawings ^. It is dominated by collapsing (slope) debris and clay, and the underlying bedrock surface is Silurian sand and shale, with complex shapes. It was destroyed on June 12, 1985 under the influence of groundwater environment changes. The monitoring time of the landslide in this embodiment is from January, 1978 to the destruction of the landslide instability. The determination process of the slope dynamic stability coefficient of the present invention is as shown in Figure 1, and the specific implementation steps are as follows:

Step 1: Monitor the basic data of slope groundwater level and displacement

① Monitoring instruments: groundwater level monitoring equipment: a, pressure water level gauge, b, air pressure compensation device; slope displacement monitoring equipment: wireless GPS displacement monitoring equipment (see Figure 2);

② According to the key positions and characteristics of the landslide’s main sliding area, tensile cracks and shear outlets at the rear edge, as well as the zonal distribution of the landslide and the exposed bedrock on both sides, select point F on the slope (see Figure 4), Point F is used as the analysis target monitoring point and sets the displacement reference point. the

③A pressure water level gauge is installed at the bottom of the borehole at the selected monitoring point F of the landslide to monitor the change of the groundwater level; a wireless GPS displacement monitoring device is arranged at the position of the displacement monitoring reference point and the slope drilling monitoring point to monitor the reference point the landslide displacement rate. the

④ The monthly time interval is used to transmit the data of landslide displacement and groundwater monitoring data to the remote monitoring room through the data signal collector of the slope site at the same cycle, and batch processing software such as Excel is used for monitoring data in the monitoring room at regular intervals. After preprocessing, the groundwater level value (see Table 1), slope displacement rate value and acceleration value (see Table 2-3) are obtained. the

Step 2: Determine the groundwater dynamic unloading parameters and displacement response parameters of the landslide

1) Determination of groundwater level unloading parameters

According to the above-mentioned monitoring data of the groundwater level in the landslide area, the statistical analysis and prediction cycle of the landslide is determined to be one year, based on the difference ΔH between the groundwater level H _i of a certain month and the ground water level H _i-1 of the previous month in an unloading cycle, When ΔH < 0, it is judged as unloading, and when ΔH > 0, it is judged as loading. Therefore, the unloading month and unloading interval of a groundwater action cycle are obtained. According to the hydrodynamic unloading interval, ΔH is divided into Statistics of the positive and negative values of the unloading load of the year and take the average value, which can be used to obtain the unloading load sequence of the groundwater level and (See Table 4).

2) Determination of displacement and unloading response parameters

In the unit statistical analysis and prediction cycle, the unloading displacement response parameters of the landslide are based on the displacement acceleration a equal to zero, the unloading response value is less than zero, and the loading response value is greater than zero. The slope displacement acceleration is counted according to the positive and negative values of the unloading response and the mean value is taken to obtain the mean value of the displacement acceleration response of the unloading sequence and (See Table 4).

Table 1 The groundwater level data table of a certain landslide (unit: mm)

Table 2 Monthly displacement rate of point F of a landslide (unit: mm/s)

Table 3 Monthly displacement acceleration rate of point F of a landslide (unit: mm/s2)

Table 4 Unloading parameters and unloading response parameters of a landslide point F

Note: The unit of the unloading parameter is mm; the unit of the displacement response value is mm/month2. the

Step 3: Determination of the parameters of the landslide groundwater dynamic unloading load-displacement response ratio

In Table 4 Substituting the sequence into the accumulation landslide unloading load response ratio prediction model formula (4), the unloading load response ratio time series (see Table 5) and the unloading load response ratio time curve (see Figure 5) of Xintan landslide monitoring point F are obtained.

Table 5 The unloading load response ratio of a certain landslide point F

Step 4: Determination of landslide dynamic stability coefficient

1) Determination of the quantitative relationship between slope damage variables and unloading load response ratio parameters

According to the unloading load-response ratio parameter of the slope in step 2 and the quantitative relationship between the slope damage variable D and the unloading load-response ratio parameter D _t = 1-γ _t , the slope loss variable can be obtained as shown in Table 6:

Table 6: Damage variable values of point F of a landslide

2) Determination of dynamic stability coefficient of water-induced landslide

According to the quantitative relationship between damage variable and stability coefficient in slope engineering (see principle 3) and formula (5) can determine the size of the water-induced landslide dynamic stability coefficient (see Table 7) and the time series curve of the stability coefficient (see Figure 6):

Table 7: Stability coefficient of point F of a landslide

Step 5: Determination of early warning criteria for water-induced landslide instability In the actual work of landslide prevention and engineering survey and design, a safety reserve is usually set for the stability factor to obtain a safety factor K as the criterion for its stability. criterion. According to the importance of slope stability and the complexity of slope geological conditions, as well as the "Code for Geological Hazard Prevention Engineering Survey" (DB50/143-2003) and "Code for Slope Design of Water Conservancy and Hydropower Engineering" (SL386-2007), it can be integrated Determine the slope stability safety factor K = 1.25. By comparing the dynamic stability factor F _t of the slope determined in the above steps with the traditional safety factor K=1.25, the dynamic early warning evaluation and treatment design of the stability of the water-induced slope can be quickly and accurately carried out.

According to the slope stability coefficient at F point obtained in step 4, it can be concluded that the slope stability coefficient gradually decreased from 1978 to 1984, but they were all greater than the slope design safety factor K=1.25, indicating that the slope The stability has been decreasing but in a stable state; the stability factor of the slope dropped suddenly from 1984 to 1985 and was less than the design safety factor K=1.25, indicating that the slope suffered a large damage during this period and eventually became unstable . The above calculation and analysis results of the actual slope stability coefficient are basically consistent with the actual slope displacement and instability law, which shows that the slope stability coefficient and instability early warning criterion determined by using the nonlinear dynamic unloading load-response ratio parameter It is effective and has strong forecasting function and practical value. the

Claims (1)

1. A method for determining the coefficient of dynamic stability of a slope based on groundwater level and displacement monitoring, is characterized in that: it comprises the following specific steps: 1. Monitoring the basic data of slope groundwater level and displacement ① Monitoring equipment: groundwater level monitoring equipment: a, pressure water level gauge, b, air pressure compensation device; slope displacement monitoring equipment: wireless GPS displacement monitoring equipment; ② Arrange monitoring points on the main sliding surface of the monitoring slope corresponding to the slope surface, and arrange N monitoring points for slope displacement changes at equal distances from the trailing edge rupture wall to the leading edge shear outlet slope according to the actual terrain of the slope surface, where N is greater than Or an integer equal to 1; Displacement monitoring reference points shall be arranged in stable bedrock or non-deformed areas outside the monitoring landslide mass, no less than 3 to form a control network; ③Groundwater level monitoring method: Drill holes at the selected monitoring points on the slope. The depth of the drill holes should reach the bedrock surface or below the groundwater level in previous years. Additional air pressure compensation device to jointly monitor the change of groundwater level; ④Slope displacement monitoring method: Arrange wireless GPS displacement monitoring equipment at the positions of displacement monitoring reference points and slope drilling monitoring points; ensure that the buried slope displacement change monitoring equipment is closely integrated with the surface of the landslide body, and the monitoring points are monitored horizontally and vertically. Monitor the displacement change value; ⑤Real-time monitoring of the groundwater level and displacement of the landslide with a certain time interval accuracy, and record the monitoring data of the groundwater level and displacement at the same time, and transmit the monitoring data to the remote monitoring room through the slope site data signal collector, and classify and preprocess the monitoring data ; 2. Determination of dynamic unloading parameters and displacement response parameters of landslide groundwater ① Determination of groundwater level unloading parameters According to the monitoring data, determine the statistical analysis and prediction cycle of the landslide, and based on the statistical analysis and prediction cycle, the forecasting unit counts the groundwater level of the landslide in a certain month and the groundwater level of the previous month difference : Formula 1) In formula (1) As a hydrodynamic unloading standard; when When , it is determined that the landslide is loaded; when When , it is determined that the landslide is unloaded; According to the statistics of positive and negative values of unloading load in each unloading cycle and take the average value, the groundwater level unloading parameters of the unloading sequence can be obtained respectively and ; ②Determination of displacement and unloading response parameters In the unit statistical analysis and prediction period, the unloading load displacement response parameters of the landslide are expressed in terms of displacement acceleration Equal to zero is the benchmark, less than zero is the unloading response value, and greater than zero is the loading response value. The slope displacement acceleration is counted according to the positive and negative values of the unloading response and the average value is taken to obtain the average value of the displacement acceleration response of the unloading sequence and ; 3. Determination of the parameters of the landslide groundwater dynamic unloading load-displacement response ratio ① Determination of response rate of landslide unloading Based on modern nonlinear scientific theory, the mean value of slope displacement acceleration unloading response The corresponding groundwater level unloading average The ratio is determined as the slope dynamic unloading displacement response rate , load the response mean value of slope displacement acceleration The corresponding groundwater table loading mean The ratio is determined as the slope dynamic loading displacement response rate ,Right now: Formula (2) Formula (3) ② Determination of the parameters of the landslide groundwater dynamic unloading load-displacement response ratio According to formula (2) and formula (3) and the definition of unloading load-response ratio, the parameters of slope groundwater level dynamic unloading-displacement response ratio can be determined as: Formula (4) 4. Determination of dynamic stability coefficient of water-induced landslide ① Determination of the quantitative relationship between slope damage variables and unloading load response ratio parameters According to the principle (2) of the present invention, the quantitative relationship between the damage variable D and the unloading load-response ratio parameter is as follows: Formula (5) Equation (5) shows that the unloading load-response ratio of rock and soil materials There is a one-to-one quantitative relationship between it and its damage variable D; ②Determination of dynamic stability coefficient of water-induced landslide Quantitative relationship between damage variables and stability coefficient determined by limit equilibrium evaluation method in slope engineering and formula (5) can determine the dynamic stability coefficient of water-induced landslide as: Formula (6) Formula (6) shows that there is a one-to-one correspondence between the unloading load response ratio and the slope stability coefficient; 5. Determination of early warning criteria for water-induced landslide instability In the actual work of landslide prevention and engineering investigation and design, a safety reserve is usually set for the stability factor to obtain a safety factor K as the criterion for its stability, based on the importance of slope stability and the geological conditions of the slope The degree of complexity and specifications such as "Code for Geological Hazard Prevention and Control Engineering Survey" (DB50/143-2003) and "Code for Design of Slopes in Water Conservancy and Hydropower Projects" (SL386-2007) can comprehensively determine the stability safety factor K of the slope, such as K= 1.3, 1.25, 1.15, etc.; through the slope dynamic stability coefficient determined in the above steps Compared with the traditional safety factor K, it can quickly and accurately carry out dynamic early warning evaluation and treatment design for the stability of water-induced slopes, that is, when When , the slope is in a stable state; when , the slope is in an unstable state.