Seepage Deformation Research Articles

Three-dimensional fully coupled study of groundwater seepage and soil deformation under the action of cyclic pumping and recharge

Abstract. This study was undertaken in order to accurately analyze the land subsidence that is caused by the change in the seepage and stress fields during the pumping and recharge of groundwater. Based on Biot's consolidation theory and groundwater seepage theory (combined with theory regarding the nonlinear rheology of soil), the constitutive relationship of soil was extended to viscoelastic plastic; concurrently, considering the dynamic changes in hydraulic parameters and soil mechanical parameters, a three-dimensional fully coupled model of groundwater seepage and soil deformation was established. Using the groundwater recycling pumping and recharge test conducted by Land Subsidence Monitoring and Early Warning Center in Cangzhou City as an example, the site was divided into four loose porous aquifers. A constantly circulating pumping–recharge flow was simulated numerically, and numerical simulation was carried out on the third and fourth confined aquifers. The influence of groundwater seepage on soil deformation was analyzed, and the variation in hydraulic parameters and soil mechanical parameters were studied under the influence of the abovementioned cyclic pumping and recharge. The results show that soil deformation lags behind the change in the groundwater level, and that permanent residual deformation of soil is produced by water level fluctuations during groundwater pumping–recharge cycles. The effective porosity, the permeability coefficient and the Poisson ratio are positively correlated with the water level fluctuation in groundwater pumping–recharge cycles, whereas the modulus of deformation is negatively correlated with the water level fluctuation in groundwater during this process. All parameters change, and this change is permanent. The simulated results are in good agreement with the measured values.

Slope Stability Analysis of “Vorobyovy Gory” Landslide in Moscow

There are many engineering-geological problems in Moscow, including seepage deformation, karst and landslide. Among them, landslides develop along the Moscow River and its branches. This paper aims to analyze the slope stability of “Vorobyovy Gory” landslide with the help of the program GeoStudio. According to the limit equilibrium method, we can know the slope stability. In addition, we can know the internal friction angle among in the physical and mechanical parameters of soil layer has the greatest influences on its stability by sensitivity analysis. Finally, we can get the probability of damage by probabilistic analysis.

Numerical Study on Vertical and Horizontal Seepage Deformation of Silty Soil

In this paper, the PFC3D fluid-solid coupling calculation module is used to simulate the seepage deformation process of silty sand under vertical and horizontal seepage. The seepage mechanism such as particle contact, flow field distribution, critical hydraulic slope and particle motion of silty sand under different seepage direction is analyzed. The numerical simulation results show that the critical hydraulic gradient of silt sand in vertical seepage is higher than the critical hydraulic gradient in horizontal seepage.

Feature Analysis and Control Method of Seepage Deformation of Rock and Soil in Port and Coast

ABSTRACT Wang, S.; Liu, D., and Wang, Z., 2018. Feature analysis and control method of seepage deformation of rock and soil in port and coast. In: Liu, Z.L. and Mi, C. (eds.), Advances in Sustainable Port and Ocean Engineering. Journal of Coastal Research, Special Issue No. 83, pp. 436–441. Coconut Creek (Florida), ISSN 0749-0208. It is difficult to effectively reflect seepage deformation features and development process of rock and soil by detecting the seepage hazard of rock and soil and concentrated seepage channel using current seepage deformation feature analysis methods. It cannot directly evaluate the anti-seepage performance of coastal rock and soil. This paper presents a method for analysis and control of seepage deformation of rock and soil in port and coast. By determining the type of seepage deformation of soil and the critical hydraulic slope or the allowable hydraulic slope, it is determined whether the dam foundation is deformed due to seepage by the comparison between the critical hydrauli...

Improved similarity criterion for seepage erosion using mesoscopic coupled PFC–CFD model

Conventional model tests and centrifuge tests are frequently used to investigate seepage erosion. However, the centrifugal test method may not be efficient according to the results of hydraulic conductivity tests and piping erosion tests. The reason why seepage deformation in model tests may deviate from similarity was first discussed in this work. Then, the similarity criterion for seepage deformation in porous media was improved based on the extended Darcy-Brinkman-Forchheimer equation. Finally, the coupled particle flow code–computational fluid dynamics (PFC-CFD) model at the mesoscopic level was proposed to verify the derived similarity criterion. The proposed model maximizes its potential to simulate seepage erosion via the discrete element method and satisfy the similarity criterion by adjusting particle size. The numerical simulations achieved identical results with the prototype, thus indicating that the PFC-CFD model that satisfies the improved similarity criterion can accurately reproduce the processes of seepage erosion at the mesoscopic level.

Simulation of Particle Flow Code for Similarity Analysis of Seepage Deformation

Simulation of Particle Flow Code for Similarity Analysis of Seepage Deformation

Numerical Simulation of Piping Mechanism under Unsteady Flow

Used the numerical method, considered the rising speed of head of seepage deformation, with the aid of the method of particle flow in micro layer to study the occurrence and development of the law of seepage failure. Numerical simulation was designed based on the study of the theory. Conducting piping tests of the soil samples by controlling water head. The results show that, the effects of loaded once on the orifice area was large, and also the most insecure. And the test result verifies the correctness of theoretical analysis. The results are valuable to further probing into the piping mechanism in sandy soils.

Numerical analysis of seepage–deformation in unsaturated soils

A coupled elastic–plastic finite element analysis based on simplified consolidation theory for unsaturated soils is used to investigate the coupling processes of water infiltration and deformation. By introducing a reduced suction and an elastic–plastic constitutive equation for the soil skeleton, the simplified consolidation theory for unsaturated soils is incorporated into an in-house finite element code. Using the proposed numerical method, the generation of pore water pressure and development of deformation can be simulated under evaporation or rainfall infiltration conditions. Through a parametric study and comparison with the test results, the proposed method is found to describe well the characteristics during water evaporation/infiltration into unsaturated soils. Finally, an unsaturated soil slope with water infiltration is analyzed in detail to investigate the development of the displacement and generation of pore water pressure.

Experimental Research on Fine Sand and Filter Material of Xing-Long Hydroproject Dam Foundation

The Xing-long hydro project is situated on fine sand foundation, whose seepage stability is a vital factor to the safety of the buildings. By means of field sampling, seepage deformation test and filter test to fine sand and filter material, the seepage deformation character of fine sand and filter material are studied. The seepage failure gradient of fine sand is very low under natural condition, its seepage stability should be satisfied under the protection of filter materials, but the protective capability of natural filter material is limited, it is suggested that the filter material be optimized by getting rid of the particles less than 0.5mm.

Conceptual data model and method of settlement calculation for deformation and water release from saturated soft soil

Research on the seepage deformation of saturated soft soil has resulted in many achievements based, mainly, on existing seepage-deformation control equations. In reality, however, these control equations and related parameters suffer from many problems. The conductivity coefficient in the seepage control equation and the consolidation coefficient in the consolidation equation clearly resemble each other in form. However, in existing regulations and practice, soil deformation is rarely calculated by substituting the conductivity coefficient obtained from field hydrogeological experiments for the consolidation coefficient. Similarly, seepage is seldom calculated by substituting the conductivity coefficient with the consolidation coefficient obtained from consolidation experiments. This can be attributed to the fact that the two coefficients have some obvious differences. Moreover, the settlement deformation of soil calculated using the existing seepage and consolidation models does not agree very well with the measured deformation. Also, the values calculated using different models usually deviate markedly. Research indicates that these problems derive from the fact that the seepage and consolidation equations are based on different concepts of elementary volume. This study proposes using two separate elementary volume concepts: deformation elementary volume and control elementary volume. The concepts are adopted for saturated soft soil and the results used to analyze the relationships and differences between the two concepts. Moreover, we developed a conceptual data model (CDM) for the water released from and the deformation of the saturated soil. The model discloses the differences between the consolidation and conductivity coefficients both in their physical significances and magnitudes. The inter-relationship between the two coefficients is also revealed. An analytical solution for the deformation and water released from saturated soft soil is deduced based on the CDM model and the relationship between the hydrogeological and consolidation deformation parameters is established. A physical test model for saturated soft soil under certain conditions is also designed to verify the analytical solution using a method of curve fitting. Seepage and deformation tests and case studies show that the parameters calculated using the consolidation model are in agreement with those obtained from the CDM seepage model based on the measured data for flux and settlement vs. time. Furthermore, the relationship between conductivity and consolidation coefficients is verified. The method suggested in this paper is generally applicable to problems involving the consolidation coefficient, volume compressibility, conductivity coefficient, hydraulic conductivity, and specific storage of saturated soft soil, etc. Thus, its potential applications are numerous.

Study on the Stability of Large Cross-River Shield Tunnel Face with Seepage

By 3D numerical analysis, the seepage force on the tunnel face was obtained and shows linearly increasing trend with the water level. By considering the average seepage force on the wedge boundary of 3D trapezoidal wedge model, the limit support pressure to keep stability of tunnel face under seepage condition was obtained. The total limit support pressure increases almost linearly with the water level. In order to consider the deformation seepage coupling effect, the 3D coupled deformation and seepage numerical analysis was further used to investigate the influence of the water level on the failure of tunnel face, the results show the failure mode changes with the increase of water level, and the limit support pressure increases nonlinearly with the water level.

Gas-solid coupling analysis and numerical simulation of the dynamic process of gas drainage

Based on the basic theory of gas seepage and coal seam deformation, using the numerical simulation method, this paper established the gas-solid coupling model of gas drainage from borehole. Using multi-physical coupling analysis software, the authors studied the stress change conditions around the drainage borehole, the influence of the gas drainage effect caused by the drilling gap, and the gas drainage effect under the conditions of different borehole radius and different permeabilities. The results show that the effective drainage radius is 1.03 m during 30 days of drainage. The effect of the diameter change of the drainage borehole is limited, but the influence of coal seam permeability is much bigger. After the same drainage period, the greater the permeability of coal seam is, the bigger the drainage radius is. For a low permeability coal seam, coal miners should take pressure-relief measures and increase the permeability to improve the drainage effects before draining gas through drilling.

The two main mechanisms of Glacier Lake Outburst Flood in Tibet, China

With the global warming, the disasters of Glacier Lake Outburst Flood (GLOF) have taken place frequently in Tibet in recent years and attracted more and more attention. A systematic survey was conducted on the 19 GLOFs in Tibet to study their two main mechanisms. Investigations indicated that all the events occurred in end-moraine lakes, and the outburst occurred partially and instantly. And the breach had the shape of an arc or a trapezoid in overflow outburst and its top width was 3-5 times more than the height. The two main mechanisms of GLOFs in Tibetan end-moraine Lake were overflow and piping, and the overflow mechanism caused by iceberg collapse was dominated in most cases. A formula was proposed to calculate the critical thickness of iceberg tongue that determines the collapse. Granular analysis of the moraine materials revealed that seepage deformation is crucial in the outburst process. Finally, we conducted a case study of the Guangxiecuo Lake to show its possible process of outburst and estimated the peak discharge of the resulted flood.

Experimental Study of the Seepage Deformation of Cement-Soil

Cement-soil is a kind of hydraulic composite building materials which is made by a certain percentage of cement soil particles and water. In order to make a deep research of seepage deformation and the variation law of cement-soil, laboratory test methods were adopted, carrying on deformation tests of indoor penetration on dry density, cement content and age etc, the factors owning outstanding effect on the seepage deformation and failure of cement-soil. The results shows that the seepage deformation and failure appear to change in certain laws with dry density, cement content and age. The gradient of seepage deformation and failure can reach one thousand under the condition that cement percentage is 5%, compaction maximum dry density is standard, and the age is 7 days. And numerical value will be enhanced significantly with the increase of cement content, dry density and the prolong of age. The seepage deformation and failure of cement-soil is not ordinary piping effect or soil-flow failure, but the form of shearing failure. The conclusion has not only a positive exploration significance of the academic research of the seepage deformation and failure of cement-soil, but also a certain practical significance on the geotechnical construction applying cement soil as impermeability.

On the Seepage Stability of a Tailing Dam in Wushan Copper Mine

The tailing pond of Wushan copper mine is located in a valley among the mountains, with kinds of hidden troubles like the overflow of the saturation line, the swamping and piping of partial section, and some local deformation, which appeared on both the starter dam and the tailing embankment in the early stage. To meet the requirement of production, a new tailing pond named No.2 Tailing Pond was built in the downstream of the original No.1tailing pond. At present, in No.1 dam, the part below 37m water level was totally submerged by the water, then the condition of the seepage field will change with the rising water level. For the safety of production and to provide a scientific basis to the management of the tailing dam, an analysis of seepage stability at four different conditions of two sections was carried out based on the field conditions of the dam. Finally, a comparison between the simulated results and the measured results was made, the results show that the existing drainage system is safe and effective, and the seepage deformation of Wushan tailing dam will not happen.

An Innovation Simulation Method for Flow State Evolution Laws of Water Inflow and Inrush in Course of Tunnel Excavation (Part II: Applications)

In order to avoid heavy casualties and economic losses, and to get an insight into flow state evolution laws of water inflow and inrush in course of tunnel excavation, simulations were done with COMSOL Multiphysics. By coupling and linking different kinds of sub domain governing equations with boundary conditions and possibly initial conditions, three kinds of water flow state, Darcy’s law for water flow in the limestone aquifer, Brinkman equations for fast fluid in the karst conduit; and incompressible Navier-Stokes equations for freely moving of water in the excavated tunnel, are interacted and coupled with each other. Water pressure and velocity were studied and analyzed in course of tunnel excavation. It is proved that there will be no disastrous water inrush when the seepage deformation of the karst conduit is small, and that it is of vital importance to protect and support the clastic medium of karst conduit, and to strictly guard against any change of the permeability of the karst fillings.

Numerical analysis of a one‐dimensional infiltration problem in unsaturated soil by a seepage–deformation coupled method

AbstractA multiphase coupled elasto‐viscoplastic finite element analysis formulation, based on the theory of porous media, is used to describe the rainfall infiltration process into a one‐dimensional soil column. Using this framework, we have numerically analyzed the generation of pore water pressure and deformations when rainfall is applied to the soil. A parametric study, including rainfall intensity, soil–water characteristic curves, and permeability, is carried out to observe their influence on the changes in pore water pressure and volumetric strain. From the numerical results, it is shown that the generation of pore water pressure and volumetric strain is mainly controlled by material parameters α andn′ that describe the soil–water characteristic curve. A comparison with the laboratory results shows that the proposed method can describe very well the characteristics observed during the experiments of one‐dimensional water infiltration into a layered unsaturated soil column. Copyright © 2010 John Wiley & Sons, Ltd.

Environmental effects induced by excavation

Based on 3D Biot’s consolidation theory and nonlinear Duncan-Chang’s model, a 3D FEM (finite element method) program is developed considering the coupling of groundwater seepage and soil skeleton deformation during excavation. The comparison between the analysis result considering the variation of water head difference and that without considering it shows that the porewater pressure distribution of the former is distinctly different from that of the latter and that the foundation pit deformations of the former are larger than those of the latter, so that the result without considering the variation of water head difference is unreliable. The distribution rules of soil horizontal and vertical displacements around the pit and excess porewater pressure are analyzed in detail in time and space, which is very significant for guiding underground engineering construction and ensuring environment safety around the pit.

A Hydro-Mechanical Coupled Analysis of an Unsaturated River Embankment due to Seepage Flow

In this paper, a soil-water coupled elasto-plastic finite element analysis is applied to the problem of seepage flow by incorporating unsaturated seepage characteristics and assuming the pore air pressure in the unsaturated soil region to be atmospheric pressure. It is shown that the proposed soil deformation–seepage flow coupled analysis method is applicable to safety investigations of river embankments and that the existing evaluation criterion for the seepage failure of river embankments is not always on the safe side.

Aspects of turbulent seepage flow in a fill

1. For application to coarsely porous fills, the authors suggest an experimentally-based two-term formula for the fundamental seepage equation, which permits calculation of the water transmission capacity of a fill of jagged or rounded stones over a wide range of Reynolds numbers, corresponding to the transition from laminar to developed turbulent seepage. 2. To make a rough first approximation of the onset of seepage deformation of the bottom slope of a singlefraction fill, an experimental formula Eq. (12) is found for certain ranges of the parameters.