scholarly journals ANALYSIS OF COMBINED FOOTINGS ON EXTENSIBLE GEOSYNTHETIC-STONE COLUMN IMPROVED GROUND

2017 ◽  
Vol 8 (2) ◽  
pp. 57-71
Author(s):  
Priti Maheshwari
Keyword(s):  
Flexural Rigidity ◽  
Nonlinear Behavior ◽  
Bending Moment ◽  
Stone Columns ◽  
Stone Column ◽  
Model Parameters ◽  
Geosynthetic Reinforcement ◽  
Foundation Soil ◽  
Lumped Parameter ◽  
Soil Foundation

Analysis of combined footings resting on an extensible geosynthetic reinforced granular bed on stone column improved ground has been carried out in the present work. Various components of soil-foundation system have been idealized using lumped parameter modeling approach as: combined footing as finite length beam, granular layer as nonlinear Pasternak shear layer, geosynthetic reinforcement as elastic extensible membrane, stone columns as nonlinear Winkler springs and foundation soil as nonlinear Kelvin body. Hyperbolic constitutive relationships have been adopted to represent the nonlinear behavior of various elements of a soil-foundation system. Finite difference method has been employed to solve developed governing differential equations with the help of appropriate boundary and continuity conditions. A detailed parametric study has been conducted to study the effect of model parameters like applied load, flexural rigidity of footing, configuration of stone columns, ultimate bearing resistance of foundation soil and stone columns, tensile stiffness of geosynthetics and degree of consolidation on response of soil-foundation system by means of deflection and bending moment in the footing and mobilized tension in geosynthetic layer. These parameters have been found to have significant influence on the response of footing and the geosynthetic reinforcement layer. To quantify this, results have been nondimensionalized to produce design charts for ready use for the analysis of combined footings resting on such a soilfoundation system.

scholarly journals Behavior of foundation soil improved by stone column under cyclic load

2018 ◽  
Vol 239 ◽  
pp. 05015 ◽  
Author(s):  
Kwa Sally Fahmi ◽  
Mohammed Fattah ◽  
Alena Shestakova
Keyword(s):  
Finite Element ◽  
Cyclic Load ◽  
Soft Soil ◽  
Current Method ◽  
Stone Columns ◽  
Elastic Response ◽  
Stone Column ◽  
Finite Element Analyses ◽  
Foundation Soil ◽  
Rate Of Loading

This paper deals with using the stone column as a technique for the enhancement of the soft ground. The key goal of utilizing stone column is to decrease settlement and to increment the soil bearing ability, as well as decreasing the consolidation period. Nowadays, the current method concerns with various kinds of soil granular and cohesive. It is clear that the delicate soils (cohesive) possess a good settlement because of the disability of the ground to control the sidelong development and protruding of the stone sections. Moreover, the ways of utilization of the geosynthetic materials for encasement of the stone sections are other perfect ways to enhance the implementation, the quality, and firmness of stone segments. The present work investigates the behavior of the soft soil reinforced with ordinary and encased stone columns with geogrid under cyclic load. Six model tests were carried out on a soil with shear strength of about 15 kPa for both ordinary stone columns (OSC) and geogrid encased stone columns (ESC). For validating the enhanced method of utilizing stone columns, finite element model using the software PLAXIS 3D and field load exams had been applied. It was concluded that the models subjected to cyclic loading under the rate of loading 10 mm/sec reached the failure level faster than models tested under the rate of loading 5 mm/sec. The results of the finite element analyses of settlement compared with the records of settlement after the laboratory load tests seem to yield reasonably comparable values up to 50% of the design load. Afterwards, the recorded settlements show up to 60% higher values in compare with the results of the finite element analyses. This observation can be attributed to the occurrence of plastic failures under increasing load after an initial elastic response.

Simulation Experimental Research for the Influence of Embedded Ratio on SMW’s Working Traits

2011 ◽  
Vol 250-253 ◽  
pp. 2322-2326
Author(s):  
Wen Zhao Chen ◽  
Quan Chen Gao ◽  
Jun She Jiang
Keyword(s):  
Soft Soil ◽  
Back Analysis ◽  
Bending Moment ◽  
Model Parameters ◽  
Foundation Pit ◽  
Action Effect ◽  
The Core ◽  
Variation Characteristics ◽  
Soil Foundation ◽  
The Impact

Through model test, the displacement of the top of the wall and the strain of the core pile with excavating were measured and the deformation and damage characteristics of the soft soil foundation pit supported bySMWwas revealed. By parameter sensitivity analysis and back analysis,ABAQUSwas applied to build the numerical simulation model ofSMWin soft soil and the model parameters were obtained and the model was optimized. The impact of the embedded depth on the displacement of the top of the wall ,strain of the core pile, the bending moment of the core pile and the surface subside were systematic studied. The curve fitting equations of the above mentioned action effect variables with embedded ratio were obtained. Studies have shown that embedded depth was significantly influenced the working properties ofSMW. When the embedded ratio reaches a critical value, the nonlinear variation characteristics of the above mentioned action effect variables will occur and the signs of foundation pit's failure will occur.

Prediction of the Effect of Using Stone Column in Clayey Soil on the Behavior of Circular Footing by ANN Model

2018 ◽  
Vol 24 (5) ◽  
pp. 86
Author(s):  
Omar Khaleel Ismael Al-Kubaisi
Keyword(s):  
Clayey Soil ◽  
Ground Improvement ◽  
Bending Moment ◽  
Horizontal Stress ◽  
Soil Strength ◽  
Stone Columns ◽  
Stone Column ◽  
Soil Consolidation ◽  
Ann Model ◽  
Circular Footing

Shallow foundations are usually used for structures with light to moderate loads where the soil underneath can carry them. In some cases, soil strength and/or other properties are not adequate and require improvement using one of the ground improvement techniques. Stone column is one of the common improvement techniques in which a column of stone is installed vertically in clayey soils. Stone columns are usually used to increase soil strength and to accelerate soil consolidation by acting as vertical drains. Many researches have been done to estimate the behavior of the improved soil. However, none of them considered the effect of stone column geometry on the behavior of the circular footing. In this research, finite element models have been conducted to evaluate the behavior of a circular footing with different stone column configurations. Moreover, an Artificial Neural Network (ANN) model has been generated for predicting these effects. The results showed a reduction in the bending moment, the settlement, and the vertical stresses with the increment of the stone column length, while both the horizontal stress and the shear force were increased. ANN model showed a good relationship between the predicted and the calculated results.  

Distribution of Stress on Stone Column-Reinforced Soft Soil under Cylindrical Storage Tank

2014 ◽  
Vol 567 ◽  
pp. 699-704 ◽  
Author(s):  
Kousik Deb ◽  
Amit Kumar Das
Keyword(s):  
Contact Stress ◽  
Storage Tank ◽  
Ground Improvement ◽  
Soft Soil ◽  
Ground Level ◽  
Stone Columns ◽  
Stone Column ◽  
Foundation Soil ◽  
Granular Fill ◽  
Mechanical Elements

Structures with circular foundation (chimney, silo, oil tank) constructed on compressible soft soil, often have to opt for ground improvement like stone columns before construction. In this paper, the stress distribution on stone column-reinforced ground under cylindrical storage tank has been presented. Actual foundation soil reinforced with stone column is assumed as composite ground of soil and hollow cylindrical stone rings keeping the area ratio constant to carry the analysis in axi-symmetric condition. The soft soil, stone columns and granular fill are idealized using mechanical elements. The floor slab of the storage tank is assumed to be flexible enough to satisfy the theory of thin plate. Governing differential equations are derived to determine the vertical settlement and solved with finite difference technique. Contact stress at ground level is calculated from vertical settlement. It is observed that soft soil experiences heavy settlement and contact stress when the tank is full despite of low spacing to diameter ratio (S/dc = 3) and reasonable modular ratio (Ec/Es = 20). It is also observed that stress acting on edge stone column is lower as compared to the stress acting on center stone column even under uniformly loaded condition.

scholarly journals The behaviour of the clay soil reinforced by stone column encased with geogrid under cyclic load

2018 ◽  
Vol 1 ◽  
pp. 33-38
Author(s):  
Kwa S.F. ◽  
Kolosov E.S.
Keyword(s):  
Bearing Capacity ◽  
Cyclic Load ◽  
Clay Soil ◽  
Soft Clay ◽  
Soil Improvement ◽  
Stone Columns ◽  
Excess Pore Pressure ◽  
Stone Column ◽  
Foundation Soil ◽  
Saturated Clay

The behavior of the fully saturated clay soil reinforced by stone columns subjected to cyclic load is of considerable very important in the design of railway subgrades, these soft clay soil are characterized by high settlement and low bearing capacity because of the excess pore pressure due to heavy freight trains significantly reduces the bearing capacity which causes serious problems, the used of stone column for reinforced the saturated clay soil will reduced the settlement and increase the bearing capacity. The purpose of the current research is cases study of foundation soil improvement by reduced the settlement for a building structure using stone columns system with and without geogrid encasement under cyclic load with rate of loading 5 mm/sec.

scholarly journals Unraveling the time-dependent relevance of input model uncertainties for a lumped hydrologic model of a pre-alpine karst system

2021 ◽  
Author(s):  
Daniel Bittner ◽  
Beatrice Richieri ◽  
Gabriele Chiogna
Keyword(s):  
Groundwater Recharge ◽  
Temporal Variations ◽  
Hydrologic Model ◽  
Time Dependent ◽  
Model Parameters ◽  
Lumped Parameter ◽  
Hydrodynamic Processes ◽  
Input Model ◽  
Karst Model ◽  
Input Uncertainties

AbstractUncertainties in hydrologic model outputs can arise for many reasons such as structural, parametric and input uncertainty. Identification of the sources of uncertainties and the quantification of their impacts on model results are important to appropriately reproduce hydrodynamic processes in karst aquifers and to support decision-making. The present study investigates the time-dependent relevance of model input uncertainties, defined as the conceptual uncertainties affecting the representation and parameterization of processes relevant for groundwater recharge, i.e. interception, evapotranspiration and snow dynamic, on the lumped karst model LuKARS. A total of nine different models are applied, three to compute interception (DVWK, Gash and Liu), three to compute evapotranspiration (Thornthwaite, Hamon and Oudin) and three to compute snow processes (Martinec, Girons Lopez and Magnusson). All the input model combinations are tested for the case study of the Kerschbaum spring in Austria. The model parameters are kept constant for all combinations. While parametric uncertainties computed for the same model in previous studies do not show pronounced temporal variations, the results of the present work show that input uncertainties are seasonally varying. Moreover, the input uncertainties of evapotranspiration and snowmelt are higher than the interception uncertainties. The results show that the importance of a specific process for groundwater recharge can be estimated from the respective input uncertainties. These findings have practical implications as they can guide researchers to obtain relevant field data to improve the representation of different processes in lumped parameter models and to support model calibration.

scholarly journals A flexible framework for sequential estimation of model parameters in computational hemodynamics

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Christopher J. Arthurs ◽  
Nan Xiao ◽  
Philippe Moireau ◽  
Tobias Schaeffter ◽  
C. Alberto Figueroa
Keyword(s):  
Unscented Kalman Filter ◽  
Three Dimensional ◽  
Synthetic Data ◽  
Sequential Estimation ◽  
Wall Material ◽  
Patient Specific ◽  
Model Parameters ◽  
Computational Framework ◽  
Lumped Parameter ◽  
Estimation Of Model Parameters

AbstractA major challenge in constructing three dimensional patient specific hemodynamic models is the calibration of model parameters to match patient data on flow, pressure, wall motion, etc. acquired in the clinic. Current workflows are manual and time-consuming. This work presents a flexible computational framework for model parameter estimation in cardiovascular flows that relies on the following fundamental contributions. (i) A Reduced-Order Unscented Kalman Filter (ROUKF) model for data assimilation for wall material and simple lumped parameter network (LPN) boundary condition model parameters. (ii) A constrained least squares augmentation (ROUKF-CLS) for more complex LPNs. (iii) A “Netlist” implementation, supporting easy filtering of parameters in such complex LPNs. The ROUKF algorithm is demonstrated using non-invasive patient-specific data on anatomy, flow and pressure from a healthy volunteer. The ROUKF-CLS algorithm is demonstrated using synthetic data on a coronary LPN. The methods described in this paper have been implemented as part of the CRIMSON hemodynamics software package.

Application and Validation of Practical Tools for Nonlinear Soil-Foundation Interaction Analysis

2010 ◽  
Vol 26 (1) ◽  
pp. 111-129 ◽  
Author(s):  
Sivapalan Gajan ◽  
Prishati Raychowdhury ◽  
Tara C. Hutchinson ◽  
Bruce L. Kutter ◽  
Jonathan P. Stewart
Keyword(s):  
Interaction Analysis ◽  
Model Performance ◽  
Shallow Foundations ◽  
Winkler Foundation ◽  
Gap Formation ◽  
Foundation Soil ◽  
Lateral Connection ◽  
Practical Guidelines ◽  
Soil Foundation ◽  
The Moment

Practical guidelines for characterization of soil-structure interaction (SSI) effects for shallow foundations are typically based on representing foundation-soil interaction in terms of viscoelastic impedance functions that describe stiffness and damping characteristics. Relatively advanced tools can describe nonlinear soil-foundation behavior, including temporary gap formation, foundation settlement and sliding, and hysteretic energy dissipation. We review two tools that describe such effects for shallow foundations and that are implemented in the computational platform OpenSees: a beam-on-nonlinear-Winkler foundation (BNWF) model and a contact interface model (CIM). We review input parameters and recommend parameter selection protocols. Model performance with the recommended protocols is evaluated through model-to-model comparisons for a hypothetical shear wall building resting on clay and model-data comparisons for several centrifuge test specimens on sand. The models describe generally consistent moment-rotation behavior, although shear-sliding and settlement behaviors deviate depending on the degree of foundation uplift. Pronounced uplift couples the moment and shear responses, often resulting in significant shear sliding and settlements. Such effects can be mitigated through the lateral connection of foundation elements with tie beams.

A Lumped Parameter Electromechanical Model for Describing the Nonlinear Behavior of Piezoelectric Actuators

1997 ◽  
Vol 119 (3) ◽  
pp. 478-485 ◽  
Author(s):  
M. Goldfarb ◽  
N. Celanovic
Keyword(s):  
System Analysis ◽  
Nonlinear Behavior ◽  
Piezoelectric Actuators ◽  
Bond Graph ◽  
Lumped Parameter Model ◽  
Input Output ◽  
Mechanical Stiffness ◽  
Analysis And Design ◽  
Lumped Parameter ◽  
Proposed Model

A lumped-parameter model of a piezoelectric stack actuator has been developed to describe actuator behavior for purposes of control system analysis and design, and in particular for control applications requiring accurate position tracking performance. In addition to describing the input-output dynamic behavior, the proposed model explains aspects of nonintuitive behavioral phenomena evinced by piezoelectric actuators, such as the input-output rate-independent hysteresis and the change in mechanical stiffness that results from altering electrical load. Bond graph terminology is incorporated to facilitate the energy-based formulation of the actuator model. The authors propose a new bond graph element, the generalized Maxwell resistive capacitor, as a lumped-parameter causal representation of rate-independent hysteresis. Model formulation is validated by comparing results of numerical simulations to experimental data.

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