scholarly journals A Geostatistical Evolution Strategy for Subsurface Characterization: Theory and Validation Through Hypothetical Two‐Dimensional Hydraulic Conductivity Fields

2020 ◽  
Vol 56 (3) ◽  
Author(s):  
Eungyu Park
Keyword(s):  
Hydraulic Conductivity ◽  
Evolution Strategy ◽  
Two Dimensional ◽  
Subsurface Characterization

scholarly journals Soil water management problems using fuzzy arithmetic

2013 ◽  
Vol 11 (4) ◽  
pp. 556-565
Keyword(s):  
Hydraulic Conductivity ◽  
Uncertain Data ◽  
Triangular Fuzzy Number ◽  
Effective Porosity ◽  
Specific Yield ◽  
Fuzzy Arithmetic ◽  
Two Dimensional ◽  
Fuzzy Analysis ◽  
Management Problems ◽  
Α Level

Drainage management problems are usually very hard to simulate due to the uncertainty of the hydraulic parameters involved. Fuzzy analysis is one of the available tools that can be used for such problems, involving uncertain data. A fuzzy analysis approach usually involves the consideration of several α-level cuts and an analytical approach or an explicit scheme approach for the PDE's discretization. Several application examples of this approach are listed in the literature, including uncertainty in hydraulic conductivity, specific yield, transmissivities, porosities, dispersivities, and deoxygenation rate coefficient. A methodology for the simulation of drainage problem having vague values of hydraulic parameters is introduced in this paper, and an analytical solution for a two-dimensional drainage application is presented. The two-dimensional problem of drainage is handled using fuzzy analysis by defining the hydraulic conductivity K as a triangular fuzzy number (TFN). The method of interval analysis is used in all the α-level cut examples. A solution is obtained using eleven α-level cuts and also solutions for two, three, and five α-level cuts are presented. Trials for different values of effective porosity are also performed. Finally conclusions on the necessary number of α-cuts utilized for drainage problems are drawn.

Effect of Biological Clogging on Infiltration Rate in Soil Treatment Systems

1990 ◽  
Vol 22 (3-4) ◽  
pp. 101-108 ◽  
Author(s):  
Takuya Kawanishi ◽  
Hiroyuki Kawashima ◽  
Kazuyuki Chihara ◽  
Motoyuki Suzuki
Keyword(s):  
Hydraulic Conductivity ◽  
Numerical Model ◽  
Substrate Concentration ◽  
Infiltration Rate ◽  
Biomass Growth ◽  
Two Dimensional ◽  
Soil Hydraulic Conductivity ◽  
Percolation Rate ◽  
Flow Experiments ◽  
Biological Clogging

Effect of biomass on the soil hydraulic conductivity was clarified on andosol soil. The approximate value of the maximum allowable density of biomass was determined, which corresponds to the minimum hydraulic conductivity of the clogged andosol soil. On the basis of these values and the mass balance of the substrate, the relation among substrate concentration, thickness of clogged zone and the percolation rate was discussed. In addition, a numerical model was constructed, and the biomass growth and the change of permeability were simulated. Calculated results were compared with the results of two-dimensional infiltration flow experiments. By using the model, the conditions to avoid infiltration failure were determined.

Groundwater flow systems in the crystalline rocks of the Okanagan Highland, British Columbia

1968 ◽  
Vol 5 (4) ◽  
pp. 813-824 ◽  
Author(s):  
D. W. Lawson
Keyword(s):  
Hydraulic Conductivity ◽  
Groundwater Flow ◽  
Flow System ◽  
Crystalline Rock ◽  
Crystalline Rocks ◽  
Two Dimensional ◽  
Local Flow ◽  
Groundwater Flow Systems ◽  
Flow Systems ◽  
Two Dimensional Flow

An investigation of the groundwater flow systems associated with the most prominent topographic expression in the Okanagan Highland (a U-shaped valley) revealed that the hydraulic conductivity of the crystalline rock varies exponentially with depth, and that the local flow systems within the upper 125 to 150 ft of the crystalline rock conduct an estimated 10 to 17 Imperial gallons per day per foot thickness in a two-dimensional flow system. These local flow systems are quantitatively the most significant in the Okanagan Highland.

scholarly journals Genesis of dewatering structures and its implications for melt-out till identification

2004 ◽  
Vol 50 (168) ◽  
pp. 17-24 ◽  
Author(s):  
Anders E. Carlson
Keyword(s):  
Hydraulic Conductivity ◽  
Drainage System ◽  
Effective Pressure ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Geotechnical Data ◽  
Critical Discharge ◽  
Two Dimensional Model

AbstractDewatering structures are a common feature used to identify melt-out till, and the lack of such structures in till could preclude deposition by melt-out. To assess the conditions under which melt-out till can be deposited without forming dewatering structures, I use geotechnical data and a quasi-two-dimensional model of geothermal melt-out. Critical discharge determined from geotechnical data suggests that low-hydraulic-conductivity till can transport up to 1.3 m3 water a–1m–2 without forming dewatering structures, which is two to three orders of magnitude greater than the volume of meltwater produced at the base of glaciers. The model indicates that debris content of the ice and the ability of the till to drain govern effective pressure during melt-out. If the drainage system is poorly developed or the till comes from debris-poor ice, effective pressure is below zero, the condition under which dewatering structures could form. However, till from relatively debris-rich ice (>40% debris) with a well-developed drainage system (channels every 10 m) can dewater without forming dewatering structures. This suggests that the lack of dewatering structures in till does not necessarily imply deposition by lodgement or deforming bed.

scholarly journals Modeling Spatial Distribution of 2D Anisotropic Hydraulic Conductivity Tensor of Fractured Groundwater Flow Media using Neural Network Case Study Grasberg Open Pit of PTFI and Surrounding

2017 ◽  
Author(s):  
Adam Verdyansyah Putra ◽  
Tedy Agung Cahyadi ◽  
Lilik Eko Widodo ◽  
Eman Widijanto
Keyword(s):  
Neural Network ◽  
Spatial Distribution ◽  
Hydraulic Conductivity ◽  
Groundwater Flow ◽  
Geological Structure ◽  
Conductivity Tensor ◽  
Open Pit ◽  
Two Dimensional ◽  
Fracture Mapping ◽  
Anisotropic Hydraulic Conductivity

Highly fractured rocks in Grasberg open pit and surrounding of PT Freeport Indonesia (PTFI) result in fractured groundwater flow media. It is due to the complex geological structure and lithological condition. Accordingly, it leads to anisotropic distribution of hydraulic conductivity. The paper will be devoted tothe modeling of two dimensional (2D) spatial distribution of hydraulic conductivity using neural network. Surface fracture mapping database will be used to estimate 2D equivalent anisotropic hydraulic conductivity tensor based on the Oda et al (1996) approach. Modeled anisotropic hydraulic conductivity is then checked at some points where the slug tests for isotropic conductivity are observed. Co-relation, validation and training between modeled and observed hydraulic conductivity is then carried out using transformation of vector anisotropic hydraulic conductivity into the scalar isotropic hydraulic conductivity. Following training step, neural network will then generate two dimensional model of anisotropic hydraulic conductivity distribution. It is beneficial for modeling of shallow anisotropic flow of groundwater distribution

Suction Stress in Unsaturated Soils Considering Hydraulic Hysteresis

2020 ◽  
pp. 110-123
Author(s):  
J. Ramírez Jiménez ◽  
J. M. Horta Rangel ◽  
M. L. Pérez Rea ◽  
E. Rojas González ◽  
T. Lopez Lara ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Unsaturated Soils ◽  
Time Lag ◽  
Degree Of Saturation ◽  
Soil Suction ◽  
Two Dimensional ◽  
Suction Stress ◽  
Hydraulic Hysteresis ◽  
Transient Thermal ◽  
Over Time

Aims: To develop a flow-moisture model that allows determining the variation of suction over time, as well as the suction stresses, using the finite element method in a two-dimensional model of unsaturated soil through an analogy with a transient thermal problem. Study Design: The variables used in this study were soil suction, hydraulic conductivity, diffusivity and degree of saturation which was represented as the  parameter of the Bishop’s effective stress equation. Place and Duration of Study: Graduate Engineering Department, Universidad Autónoma de Querétaro, between November 2019 and August 2020. Methodology: To establish the model, experimental Soil-Water Retention Curve was taken from Galaviz (2016). With this information, the curves of hydraulic conductivity and diffusivity were calculated with the methods of Fredlund et al. (2012) and Li (1996). In ANSYS 19.2, an analogous transient thermal analysis was run to determine suction changes over time in a 12 x 2.4 meters two-dimensional medium with an impermeable membrane at the center of its surface which was 4.8 meters long. Through these suction changes, the hydraulic hysteresis algorithm presented by Zhou et al. (2012) was used to calculate the respective degrees of saturation, which were considered as the  parameter to obtain the suction stresses. Results: The changes in soil suction, degree of saturation and suction stress were properly modeled. Conclusion: When considering the hydraulic hysteresis cycles, both spatial and temporal variations behaved in a similar way in the  parameters as well as in the suction stresses. Such stresses depended on the analysis period, increasing in the dry season, according to the precipitation-evapotranspiration model, and decreasing in the wetting season. A time lag was observed between the maximum and minimum stresses as greater depths were studied. Along the horizontal axis, considering the same depth, the stresses varied more in the areas adjacent to the impermeable membrane, while at the center this variation was practically null.

One- and two-dimensional finite element modelling of thaw consolidation

2021 ◽  
Author(s):  
Rajith Sudilan Dayarathne ◽  
Bipul C. Hawlader ◽  
Ryan Phillips ◽  
Dilan Robert
Keyword(s):  
Finite Element ◽  
Hydraulic Conductivity ◽  
Void Ratio ◽  
Soil Column ◽  
Nonlinear Behaviour ◽  
Two Dimensional ◽  
Fe Modelling ◽  
Rapid Reduction ◽  
Thaw Consolidation ◽  
Dimensional Finite Element

Coupled thermo-hydro-mechanical finite element (FE) modelling of thaw consolidation is presented. One-dimensional FE analyses are performed for thaw consolidation of a soil column due to self-weight and with a combination of self-weight and surcharge, with the linear and nonlinear void ratio–effective stress–hydraulic conductivity relationships of thawed soil. The nonlinear behaviour of thawed soil is modelled using a modified Drucker–Prager Cap model, while the hydraulic conductivity is varied with the void ratio. Finally, two-dimensional FE modelling of thaw consolidation around a warm pipeline buried in permafrost is performed. The rapid reduction of the void ratio with consolidation, especially at the low-stress level, results in a wide variation of hydraulic conductivity within the thawed zone. The significantly large hydraulic conductivity of soil elements along the curved thaw front, as compared to that of thaw consolidated soil, causes the flow of water along the thaw front, instead of a vertical flow, as assumed in previous 1-D thaw consolidation modelling of buried pipelines.

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