Reservoir Water Level Fluctuation Research Articles

Study on Phreatic Line of Reservoir Slope under the Rainfall and Reservoir Level Fluctuation

The determination of the phreatic line under the action of rainfall and reservoir water level fluctuation together is of great importance for reservoir slope stability analysis. However, there are no unified Formulas for the calculation of phreatic line. Homogeneous reservoir slope seepage model with inclined impermeable bed is built. Then, a conceptual model is set up based on the basic principle of seepage theory, and the approximate analytic solutions of phreatic line are derived with the Boussinesq Differential Equation of unsteady infiltration and initial value calculated in steady flow condition. And the simplified Formula, which is convenient for engineering application, is obtained by Polynomial Fitting Method.

Monitoring Model for Dam Seepage Based on Lag Effect

The traditional dam seepage monitoring model is based on the relationship of seepage elements with the upstream reservoir water level and rainfall, which includes the impact of base value, this model will weaken the effects of reservoir water level variation and rainfall on the variation of seepage elements, especially under the condition of high reservoir water level and smaller head fluctuation, so components separated by this model are not normally the practical. Based on the theory of unsteady seepage, the lag effect function has been introduced into the seepage monitoring model to take the lag effect of reservoir water level variation and rainfall into account, and the daily variation monitoring model of dam seepage elements is established. Case studies are in good agreement with original observations, so the proposed model can be used in the daily variation monitoring and forecasting of dam seepage elements.

Three Gorges Reservoir Water Level Fluctuation Influents on the Stability of the Slope's Analysis

Since the three Gorges reservoir Water storage, reservoir water level have about 30m water levels fluctuation every year, different level will lead to the bank slope infiltration lines rise and fall, and influent on the bank slopes stability. The test according to Manzo reservoir laboratory test data and geological survey report, using the finite element software of ANSYS to establish the finite element model. The model put different water level decline speed, different osmotic coefficient and the different infiltration recharge tension cases to analysis separately,the result shows:1) more greater the reductions speed, more steeper the saturation lines luffing, more adverse the slopes stability;2) more smaller the permeability coefficient, more poor the slopes drainage capacity,more steeper the infiltration line, more poor the slopes stability; 3) seepage lines position higher than no infiltration seepage lines position.

Creep model for unsaturated soils in sliding zone of Qianjiangping landslide

The mechanical behavior of sliding zone soils plays a significant role in landslide. In general, the sliding zone soils are basically in unsaturated state due to rainfall infiltration and reservoir water level fluctuation. Meanwhile, a large number of examples show that the deformation processes of landslides always take a long period of time, indicating that landslides exhibit a time-dependent property. Therefore, the deformation of unsaturated soils of landslide involves creep behaviors. In this paper, the Burgers creep model for unsaturated soils under triaxial stress state is considered based on the unsaturated soil mechanics. Then, by curve fitting using the least squares method, creep parameters in different matric suction states are obtained based on the creep test data of unsaturated soils in the sliding zones of Qianjiangping landslide. Results show that the predicted results are in good agreement with the experimental data. Finally, to further explore the creep characteristics of the unsaturated soils in sliding zones, the relationships between parameters of the model and matric suction are analyzed and a revised Burgers creep model is developed correspondingly. Simulations on another group of test data are performed by using the modified Burgers creep model and reasonable results are observed.

Bankside Stability Analysis under the Actions of Rainfall and Reservoir Water Level Fluctuation

It has been accepted that the rainfall and the reservoir water level fluctuation plays an important role in the stability of the reservoir bankside. However, at present, there has not been suitable simplification method for the project application to calculate and appraise. Therefore, based on the Boussinesq’s differential equation of unsteady-seepage and boundary condition, and Laplace’s transform, the curvilinear equation of phreatic line in landslide mass is deduced under the rainfall and the reservoir water level fluctuation conditions, and a simplified formula which can be used in the project is gained by the polynomial fitting. Meanwhile, it holds together the transmission coefficient method to write programs about the bankside stability analysis in the paper. With the Er-Liban landslide of the three Gorges Reservoir area for the computation model, this paper use the program to analyze the change rule and stability of the phreatic line under the reservoir water level fluctuation and rainfall condition.

Analysis of Dynamic Response of Landslide Stability to Reservoir Water Level Fluctuation Using Numerical Simulation

Reservoir water level is one important factor influencing the stability of landslides. The dynamic response of landslide stability under reservoir water level function and its features are analyzed using theoretical and numerical methods. The results show that, in terms of reservoir water level fluctuation and landslide permeability, the seepage filed of landslide can be divided into four types: lag behind impoundment(X-Ⅰ), lag behind drawdown(T-Ⅰ), synchronization with impoundment(X-Ⅱ) and synchronization with drawdown (T-Ⅱ). Under lag behind drawdown, at a certain rate of reservoir drawdown, the stability drops with the permeability of landslide. Under lag behind impoundment, with the rise of water level, the lower the permeability of landslide is, the more stable the landslide is. Under synchronization with impoundment or drawdown, the stability of landslide drops with reservoir impoundment and rises with reservoir drawdown.

Deformation Module Dynamic Inversion of Xietan Sewage Treatment Plant Slope when Exposed to Reservoir Water Level Fluctuation Based on Fluid-Solid Coupling Theory

This paper selects the Xietan sewage treatment plant slope as research object, used the fluid-solid coupling finite element analysis software (ABAQUS) and intelligent displacement back analysis method to dynamically inverse the deformation module of rock and soil of the slope when exposed to water level fluctuation. The results show that the calculation displacement values of measuring point which based on the inversion method is very close to that based on field measurement, which indicates the intelligent displacement back analysis method is suitable to dynamically inverse rock and soil physical and mechanical parameters of slope when exposed to reservoir water level fluctuation.

Stability of Huangtupo riverside slumping mass II# under water level fluctuation of Three Gorges Reservoir

After the normal operation of the Three Gorges Reservoir, the water level of the reservoir will fluctuate periodically. Water level fluctuation will soften the rock and soil on the banks, induce underground water fluctuation and decrease the shear strength of rock soil on the banks, and in turn affect the landslide stability. The Huangtupo (黄土坡) landslide is a typical large and complex landslide in the Three Gorges Reservoir region. In particular, the stability of its riverside slumping mass has a great stake. On the basis of the analysis of engineering geological condition and formation mechanism of the Huangtupo landslide, the authors established the 2D finite element model of riverside slumping mass II# and selected proper mechanical parameters of the rock. With the GeoStudio software, according to the reservoir running curve, the simulation on coupling effect of seepage field and stress field was conducted in 7 different modes in a year. The results showed that: ➀ Huangtupo landslide is a large and complex landslide composed of multiple slumping masses, which occurred at different phases. Before reservoir impoundment, it was stable; ➁ it is quite difficult for riverside slumping mass I# and II# to slide as a whole; ➂ the stability coefficient of riverside slumping mass II# changes with the reservoir water level fluctuations. The minimum stability coefficient occurs 48 days after the water level starts to fall and the moment when the water level falls by 11.9 m. Landslide monitoring result is consistent with the numerical simulation result, which shows that although the reservoir water level fluctuation will affect the foreside stability of the landslide and induce gradual damage, the riverside slumping mass II# is stable as a whole.

Analysis of the Influence of Reservoir Water Level Fluctuation on Bank Slope Stability

AbstractRoads in mountainous areas are always built beside the reservoir. The water level changes when water is stored or discharged, and the change in water level influences slope stability. Based on a certain bank slope project, the influence of water level fluctuation, decreased velocity, soil permeability, and excess pore water pressure on slope stability is analyzed by calculating the flow field and strength reduction of Plaxis. When the soil condition follows a drained behavior, the safety of the slope becomes decrescent and then increscent with the increase or decrease of the reservoir water level. A special water level exists at which the safety factor of slope would be minimal. With the decrease in water level, the safety of the slope following an undrained behavior of the soil would decrease by 10%, in contrast to when the soil follows a drained behavior. The faster the decrease in water level or the smaller the permeability coefficient of the soil, the worse the stability of the slope becomes.

Stability of Huangtupo I# Landslide under Three Gorges Reservoir Operation

Abstract. During the normal operation of Three Gorges Reservoir, the water level of the reservoir will fluctuate periodically, which will soften and decrease the shear strength of rock soil on the bank, meanwhile decrease the landslide stability. Huangtupo landslide is a typical large and complex landslide in the Three Gorges Reservoir Region, which is consist of four sub-landslides. In particular, the stability of its riverside Huangtupo I# landslide has a great stake. Based on the analysis of engineering geological condition of Huangtupo landslide, the 2D finite element model of Huangtupo I# landslide(The Riverside Slumping mass I#) was established, the proper mechanical parameters was selected. By using the GeoStudio software, according to the reservoir running curve, the simulation on coupling effect of seepage field and stress field was conducted in 7 different modes within the period of one year. The results showed that: ①the reservoir water level fluctuations will affect both the displacement in saturated and un-saturated area of landslide; especially when the water level drawing down sharply; ②the stability coefficient of Huangtupo I# changes with the reservoir water level fluctuations; the minimum stability coefficient occurs 48 days after the water level drawing down and the moment when the water level falls by 11.9m, under that moment the Huangtupo I# is unstable.

Continuous Monitoring of an Ice Sheet in a Reservoir Upstream of Beaumont Dam, Canada

The geomatics engineering contributions to continuous three-dimensional monitoring of ice sheet in a dam reservoir is presented in this paper. A total station robot was used to monitor the displacement of several probes placed on the surface of the ice sheet of a dam reservoir during winter seasons. Two prisms were mounted on each probe to take into account the deflection variation of the probe during a complete winter season. A similarity (Helmert) transformation was computed from measurements on control points to solve the problem of inconsistent observations. The results of the 2009 and 2010 winter campaigns at the Beaumont Dam are reported in this paper. We show that the horizontal displacements of the ice sheet, which can be as large as 20-30 cm, can vary quite differently from one winter season to another one, as a function of the temperature and its variation during winter. The horizontal displacements also depend on the probe's distance from the dam or from the reservoir banks. Vertical displacements of the ice sheet follow the reservoir water level fluctuations, especially for the probes far from the dam and reservoir banks. Three-dimensional displacements are explained by the gradual increase of the ice sheet's thickness, the snowpack accumulation, and the local constraints (hinge effects) near the reservoir perimeter. DOI: 10.1061/(ASCE)SU .1943-5428.0000060. © 2012 American Society of Civil Engineers. CE Database subject headings: Winter; Surveys; Measurement; Ice; Monitoring; Dams; Reservoirs; Transformations; Canada; Case studies. Author keywords: Winter surveys; Field measurements; Ice; Monitoring; Dam; Dam reservoir; Total station robot; Similarity (Helmert) transformation.

Study on the Relationship between Factor of Safety and Angle of Dip of Bedding Rock Slope when Exposed to Reservoir Water Level Fluctuation

The impoundment and running of Three Gorges Reservoir makes the water level fluctuate between 175m and 145m, and the water level fluctuation has been leading to the seepage field variation of bank slopes, which will bring out the stability change of bank slopes. In order to obtain the relationship between the angles of dip and factors of safety of bedding rock slopes which are generalized slope models from some bedding rock slopes failure in some reservoirs, the finite element method based on Darcy seepage theory was taken to simulate the seepage field variation of this type of bedding rock slopes when exposed to water level fluctuation, then the underground water tables of the bedding rock slopes with different angles of dip were obtained, finally the factors of safety of bedding rock slopes when water level rose and fell at speed of 0.2m/d were calculated by limit equilibrium method. Through the regulation analysis of factors of safety with the increase of angles of dip of bedding rock slopes when exposed to reservoir water level fluctuation, the relationship between factors of safety and angles of dip of bedding rock slopes was obtained.

Study on the Relationship between Factor of Safety and Angle of Dip of Bedding Rock Slope when Exposed to Reservoir Water Level Fluctuation

Study on the Relationship between Factor of Safety and Angle of Dip of Bedding Rock Slope when Exposed to Reservoir Water Level Fluctuation

Landslide monitoring with high-resolution SAR data in the Three Gorges region

Employing the well-known D-InSAR technique, we investigated landslide monitoring in the Three Gorges region using TerraSAR-X data. The experiment demonstrates that using both the amplitude and differential phase allows us to identify the precise location, deformation and time range of occurrence of certain landslides. To overcome the atmospheric effect on D-InSAR results, a time-series analysis was also carried out. The observed nonlinear relationship between the deformation and water level suggests that reservoir water level fluctuation is one of the major causes of landslides, which is significant in terms of issuing landslide warnings. In addition, the comparison of TerraSAR-X and C-band ASAR data results indicates that TerraSAR-X data provide far more reasonable deformation measurements because of their high temporal and spatial resolutions.

Analysis of Bazimen Landslide Deformation Based on GPS

Rainfall infiltration and reservoir water level fluctuation are major factors inducing slope deformation. Taking nearly three years data of Bazimen landslide in the Three Gorges Reservoir area and basing on the mathematical regression analysis method, a mathematical relationship among landslide deformation, water level and rainfall is established. And then the most adverse condition under the superposi¬tion of rainfall and reservoir water level is obtained.

Experimental Study on the Strength Difference of Two Types of Sandstones With Different Composition of Minerals Under the Conditions of Dry and Wet Cycles

Some rock slides have taken place in Three Gorges Reservoir Area, China. Many Researches on the causes of the slides shows that the more sensitive of rock strength to the reservoir water level fluctuation, the easier to fail of the rock slopes. In order to study the strength difference of different sandstones in reservoir water fluctuation zone of Three Gorges Reservoir, the authors taken two types of sandstones with different composition of minerals as a typical case to study in detail. One type of the two sandstones (called Type I) is composed of quartz, feldspar, muscovite and calcite, argillaceous cement. The other (called Type II) is composed of quartz, feldspar, sericite, argillaceous cement. Uniaxial compression tests indicate that the compressive strength of type I sandstone decreased significantly as they underwent first wet and dry cycle, and then nearly kept constant when they underwent the following wet and dry cycles, and that the compressive strength of Type II sandstones nearly kept constant when they underwent many times of wet and dry cycles.

Simulation of Landslide Seepage Field with the Action of Reservoir Water Fluctuations

Taking a landslide in the three gorges reservoir area as an example and considering the seepage field in different time periods with rise and fall of reservoir water level of the eight conditions, we use GEO-STUDIO / SEEP module to establish a seepage model and to calculate the distribution of seepage. The results showed that: the groundwater saturation line appears in the back-phenomenon during a certain range of slope in the rising water level, saturation line was concave shape, and with the rate of increase in water level increased and that concavity gradually increase; the groundwater saturation line appears in the downstream phenomenon during a certain range of slope in the drawdown water level, saturation line was convex shape, and with the rate of decline in water level increased and that convexity increases. The effective simulation studies of the greatly and cyclical fluctuations of water level under the slope seepage field has a certain reference meaning to the landslide control in the reservoir water level fluctuations about reservoir bank landslide.

Mechanism of reservoir water in the deformation of Hefeng landslide

The trial impoundment was carried on in Three Gorges Reservoir from September 27, 2008. There were strong deformation and failure in Hefeng (鹤峰) landslide when the reservoir water level descended from the altitude of 173 m. It indicates that the deformation is closely related to reservoir water fluctuation. For this reason, the effect of reservoir water in the deformation was studied, taking Hefeng landslide as an example in this article. First, the geological characteristics and deformation situation of strong deformation region are analyzed to disclose the intrinsic factors and the pattern of the deformation under the condition of water level fluctuation. Second, the stabilities of the landslide are calculated during the rising and descending processes, and the corresponding relationship between reservoir water level fluctuation and landslide deformation is further identified. At last, the seepage fields and the force condition of landslide body below the phreatic line are analyzed to reveal the effect of reservoir water. Moreover, it can be concluded that for better permeable reservoir landslide, during reservoir water rising, the favorable effect of seepage force weakens the unfavorable effect of uplift force, so the rising of reservoir water has little effect on the stability, and no deformation is caused; but during the descending of reservoir water, the unfavorable effect of seepage force is superimposed on the unfavorable effect of the uplift force, which causes the stability to dramatically decrease and leads to the failure of the accumulation body in front of the landslide.

Seismogenic permeability, ks

The temporal and spatial pattern of seismicity associated with reservoir water level fluctuations, injection of high‐pressure fluids in deep boreholes, and seasonal groundwater recharge provide a unique setting to study the hydrological properties of the seismogenic fractures. Pore pressure diffusion is primarily responsible for the build up of fluid pressures and the onset of seismicity. The hydrologic property controlling pore pressure diffusion is hydraulic diffusivity c, which is directly related to intrinsic permeability k. By analyzing more than 90 case histories of induced seismicity, we determined the hydraulic diffusivity value of fractures associated with seismicity to lie between 0.1 and 10 m2/s. This range of values of c corresponds to a range of intrinsic permeability values between 5 × 10−16 and 5 × 10−14 m2. We call this range the seismogenic permeability ks. Fractures with ks were found to be associated with Darcian flow. Fractures with permeability less than ks were aseismic, as the pore pressure increase was negligible. In fractures with permeability larger than ks, aseismic non‐Darcian flow was observed. Seismicity was uniquely associated with fractures with seismogenic permeability. Thus seismogenic permeability is an intrinsic property of fractures where pore pressure diffusion is associated with seismicity.

Rotifer Hatching from the Sediments of a Fluctuating Mainstem Reservoir

Rotifer hatching was examined for moist sediments collected from three benthic environments in a mainstem reservoir embayment, Kentucky Lake, KY: a drawdown zone with an established annual drying and wetting cycle, a floodplain that is only rarely inundated, and the permanently inundated embayment. Hatching data were compared with previous published data for laboratory-dried sediments from the same sites and with bi-weekly water-column samples over a one-year period. Of the total 44 taxa now recorded from Kentucky Lake, 18 species hatched from moist sediments and six from completely dried sediments. Taxa that emerged from moist and dried sediments were common to temporary and littoral habitats indicating that they may be better adapted for surviving diapause in a fluctuating reservoir environment. Evidence further suggests that the degree of sediment drying in drawdown and floodplain zones may affect egg hatching and that human-induced reservoir water level fluctuations may play a role in rotifer community dynamics by increasing or reducing rotifer community diversity in a single year.