scholarly journals Comparison of EPS Geofoam and Stone columns in heave reduction of expansive soils

2021 ◽  
Vol 309 ◽  
pp. 01192
Author(s):  
Thentu Jahnavi ◽  
Kattamanchi V. Kranthi Kumar
Keyword(s):  
Expansive Soils ◽  
Petroleum Industry ◽  
Vertical Direction ◽  
Stone Columns ◽  
Excess Pore Pressure ◽  
Coupled Analysis ◽  
Eps Geofoam ◽  
Swelling Soil ◽  
Granular Piles ◽  
2D Numerical Model

To reduce the swell pressures in expansive soils usually granular piles are used, but due to lack of availability there is need of a material which is highly compressible and economical also. EPS Geofoams are obtained by expanding the polystyrene polymer which is a by-product obtained from the petroleum industry. As the drainability of the Geofoam is very less a layer of Geocomposite is surrounded over the geofoam especially for allowing the drainage. So, the mechanism involved in the study is that whenever a saturated soil swells in vertical direction this Geofoam will give room to accommodate the lateral swell which leads to reduction in the vertical heave and Geocomposite will dissipate the excess pore pressure generated during swelling of the soil. In the present study an attempt was made to predict the performance of EPS Geofoam and Geocomposite in reducing the soil heave due to constant infiltration. A two dimensional (2D) numerical model was developed using GEOSTUDIO 2012 to predict the behaviour of the swelling soil due to the inclusion of Geofoams as well as stone columns. Generally coupled and uncoupled analysis are performed to study the behaviour of the swelling soil but as the uncoupled analysis is more advantageous than coupled analysis it is performed in the present study.

Numerical Simulation of a Jumper Conveying Slurry for Deep-Sea Mining

2021 ◽  
Author(s):  
Marcio Yamamoto ◽  
Tomo Fujiwara ◽  
Joji Yamamoto ◽  
Sotaro Masanobu
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Dynamic Analysis ◽  
Internal Pressure ◽  
Deep Sea ◽  
Petroleum Industry ◽  
Vertical Direction ◽  
Internal Flow ◽  
Horizontal Direction ◽  
Viscous Pressure

Abstract One key technology for Deep-Sea Mining is the riser system. The riser is already a field-proven technology in the Petroleum Industry. However, several differences exist between a petroleum production riser and a riser for Deep-Sea Mining, mainly related to the internal flow. The ore-slurry has a larger density than the hydrocarbons and shall be pumped with a much higher flowrate. The current software tools for riser’s dynamic analysis may include the internal fluid hydrostatic pressure and the centrifugal and Coriolis forces imposed by the bent pipe’s internal flow. However, the internal pressure drop is not calculated. The internal pressure alters the pipe’s effective tension and can alter the pipe’s bending moment changing its mechanical behavior. This article describes a computational script’s development to run embedded in a commercial software for riser’s dynamic analysis. Our script calculates the internal viscous pressure drop along with the jumper. This pressure is then converted into wall axial tension (buckling) and imposed on each node of the jumper’s numerical model. Each simulation case was calculated twice with and without the internal flow viscous pressure drop. The comparison with experimental data revealed that the jumper’s average position has a good agreement among all cases. However, the amplitude caused by the top oscillation showed some discrepancies. Experimental data has the highest amplitude in the horizontal direction, while the simulation without viscous pressure calculation had the smallest. The simulation with our embedded script had intermediary amplitude in the horizontal direction. The vertical direction amplitudes have the same behavior for all cases, but the experimental data showed the highest amplitude.

scholarly journals Analysis and settlement evaluation of an end-bearing granular pile with non-linear deformation modulus

2018 ◽  
Vol 40 (3) ◽  
pp. 188-201 ◽  
Author(s):  
Jitendra Kumar Sharma ◽  
Pooja Gupta
Keyword(s):  
Influence Factor ◽  
Ground Improvement ◽  
Deformation Modulus ◽  
Relative Length ◽  
Stone Columns ◽  
Linear Deformation ◽  
Dense Sand ◽  
Granular Pile ◽  
Non Linear ◽  
Granular Piles

AbstractGround improvement with granular piles increases the load-carrying capacity, reduces the settlement of foundations built on the reinforced ground and is also a good alternative to concrete pile. Granular piles or stone columns are composed of granular material, such as crushed stone or coarse dense sand. An analytical approach based on the continuum approach is presented for the non-linear behaviour of the granular pile. The formulation for pile element displacement is done considering the non-homogeneity of the granular pile as it reflects the true behaviour and also accounts for the changes in the state of the granular pile due to installation, stiffening and improvement effects. The present study shows that the settlement influence factor for an end-bearing granular pile decreases with increase in the relative stiffness of the bearing stratum. The settlement influence factor decreases with increase in linear and non-linear non-homogeneity parameters for all values of relative length. For a shorter pile, the rate of decrease of the settlement influence factor is greater in comparison to that for a longer pile. Shear stress at the soil–granular pile interface reduces in the upper compressible portion of the granular pile and increases in the lower stiffer portion of the granular pile due to the non-homogeneity of an end-bearing granular pile.

scholarly journals Axisymmetric Consolidation of Unsaturated Soils by Differential Quadrature Method

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Wan-Huan Zhou
Keyword(s):  
Pore Water ◽  
Unsaturated Soils ◽  
Differential Quadrature Method ◽  
Vertical Direction ◽  
Differential Quadrature ◽  
Excess Pore Pressure ◽  
Foundation Engineering ◽  
Quadrature Method ◽  
Governing Equations ◽  
Excess Pore

Axisymmetric consolidation in a sand drain foundation is a common problem in foundation engineering. In unsaturated soils, the excess pore-water and pore-air pressures simultaneously change during the consolidation procedure; and the solutions are not easy to obtain. The present paper uses the differential quadrature method (DQM) for axisymmetric consolidation of unsaturated soils in a sand drain foundation. The radial seepage of sand drain foundation is considered based on the framework of Fredlund’s one-dimensional consolidation theory in unsaturated soils. With the use of Darcy’s law and Fick’s law, the polar governing equations of excess pore-air and pore-water pressures of axisymmetric consolidation are derived. By using DQM, the two governing equations are transformed into two sets of ordinary differential equations. Then the solutions of excess pore-water and pore-air pressures can be obtained by Rong-Kutta method. The DQM solution can be used to deal with the case of nonuniform initial pore-air and pore-water distributions. Finally, case studies are presented to investigate the behavior of axisymmetric consolidation of unsaturated soils. The convergence analysis and average degree of consolidation, the settlements in radial and vertical direction, and the effects of different initial excess pore pressure distributions are presented, and discussed in this paper.

Mitigation of Liquefaction Hazard Using Granular Piles

2011 ◽  
Vol 2 (1) ◽  
pp. 44-66 ◽  
Author(s):  
A. Murali Krishna
Keyword(s):  
Ground Improvement ◽  
Stone Columns ◽  
Loose Sand ◽  
Short Discussion ◽  
Remedial Measure ◽  
Design Concepts ◽  
Liquefaction Mitigation ◽  
Liquefaction Hazard ◽  
Granular Piles ◽  
Surrounding Soil

In this paper, ground improvement techniques are used to mitigate liquefaction hazards. Granular piles are the preferred alternative due to several advantages. Granular piles improve the ground by reinforcing and adding density to the surrounding soil apart from providing drainage. Different mechanisms operate in the function of stone columns/granular piles in liquefaction mitigation, including Drainage, Storage, Dilation, Densification, and Reinforcement. This paper presents an overview of the use of granular piles as a liquefaction remedial measure for sand deposits. A brief description on liquefaction and the associated features is presented. A short discussion on various ground improvement methods available for liquefaction mitigation is discussed in light of the importance of granular piles. Different installation methods and design concepts for granular piles are presented. Various mechanisms of granular piles in mitigating the liquefaction potential of loose sand deposits are discussed and quantified in detail proving their effectiveness in hazard mitigation.

Liquefaction Mitigation Using Stone Columns Around Deep Foundations: Full-Scale Test Results

2000 ◽  
Vol 1736 (1) ◽  
pp. 110-118 ◽  
Author(s):  
Scott A. Ashford ◽  
Kyle M. Rollins ◽  
S. Case Bradford V ◽  
Thomas J. Weaver ◽  
Juan I. Baez
Keyword(s):  
Pore Pressure ◽  
Ground Improvement ◽  
Full Scale ◽  
Stone Columns ◽  
Excess Pore Pressure ◽  
Deep Foundations ◽  
Laterally Loaded Piles ◽  
Before And After ◽  
Laterally Loaded ◽  
Excess Pore

The results presented were developed as part of a larger project analyzing the behavior of full-scale laterally loaded piles in liquefied soil, the first full-scale testing of its kind. Presented here are the results of a series of full-scale tests performed on deep foundations in liquefiable sand, both before and after ground improvement, in which controlled blasting was used to liquefy the soil surrounding the foundations. Data were collected showing the behavior of laterally loaded piles before and after liquefaction. After the installation of stone columns, the tests were repeated. From the results of these tests, it can be concluded that the installation of stone columns can significantly increase the density of the improved ground as indicated by the cone penetration test. Furthermore, it was found that the stone column installation limited the excess pore pressure increase from the controlled blasting and substantially increased the rate of excess pore pressure dissipation. Finally, the stone columns were found to significantly increase the stiffness of the foundation system by more than 2.5 to 3.5 times that in the liquefied soil. This study provides some of the first full-scale quantitative results on the improvement of foundation performance due to stone columns in a liquefiable deposit.

Laboratory study of expanded polystyrene (EPS) geofoam used with expansive soils

2008 ◽  
Vol 26 (2) ◽  
pp. 189-195 ◽  
Author(s):  
S. Banu Ikizler ◽  
Mustafa Aytekin ◽  
Evin Nas
Keyword(s):  
Laboratory Study ◽  
Expansive Soils ◽  
Expanded Polystyrene ◽  
Eps Geofoam

scholarly journals Numerical Modeling of Water Flow in Expansive Soils with Simplified Description of Soil Deformation

2018 ◽  
Vol 65 (4) ◽  
pp. 301-313
Author(s):  
Sławomir Michalski ◽  
Adam Szymkiewicz
Keyword(s):  
Water Flow ◽  
Unsaturated Flow ◽  
Expansive Soils ◽  
Vertical Direction ◽  
Time Discretization ◽  
Soil Mass ◽  
Flow Equation ◽  
Anthropogenic Factors ◽  
Equilibrium Equations ◽  
Stress Equilibrium

AbstractIn this paper we describe a numerical model of transient water flow in unsaturated expansive soils and the resulting soil volume change. The unsaturated flow equation is solved in a 2D domain using a finite-volume method and an explicit time discretization scheme. Strains in the soil mass are calculated by two simplified approaches, assuming that the strain state is either 1D (in the vertical direction only) or 2D with equal strains in horizontal and vertical directions. The model is applied to two cases described in the literature, in which the strains were computed from the solution of the stress equilibrium equation. It is shown that the simplified methods give results which are reasonably close to the more complex approach based on the equilibrium equations. The proposed model can be used to predict time-varying soil shrinkage and swelling caused by natural and anthropogenic factors.

Increasing pull-out capacity of granular pile anchors in expansive soils using base geosynthetics

2000 ◽  
Vol 37 (4) ◽  
pp. 870-881 ◽  
Author(s):  
B R. Phani Kumar ◽  
N Ramachandra Rao
Keyword(s):  
Expansive Soils ◽  
Expansive Soil ◽  
Swelling Pressure ◽  
Ground Movement ◽  
Anchor Plate ◽  
Pull Out ◽  
Swelling Soil ◽  
Granular Pile ◽  
Load Rate ◽  
Uplift Load

Granular pile anchors are innovative and effective in resisting the uplift pressure exerted on the foundation by a swelling expansive soil. In a granular pile anchor, the foundation is anchored at the bottom of the granular pile to an anchor plate with the help of a mild steel rod. This renders the granular pile tension-resistant and enables it to offer resistance to the uplift force exerted on the foundation by the swelling soil. This resistance to uplift or pull-out load depends mainly upon the shear parameters of the pile-soil interface and the lateral swelling pressure of the soil, which confines the pile radially and prevents it from being uplifted. The resistance to uplift can be increased by placing a base geosynthetic above the anchor plate so that it forms an integral part of the granular pile anchor. The increase in resistance is due to the friction mobilized between the geosynthetic and the confining media when the uplift load acts on the pile and the geosynthetic moves along with the pile. Hence it depends on the friction between the geosynthetic and the confining media and the area and stiffness of the geosynthetic. This paper discusses the effects of these parameters on pull-out load, rate of heave, and relative ground movement near the pile surface.Key words: expansive soil, granular pile anchor, base geosynthetic, ground movement, rate of heave, pull-out load.

Challenges to modelling heave in expansive soils

2006 ◽  
Vol 43 (12) ◽  
pp. 1249-1272 ◽  
Author(s):  
Hung Q Vu ◽  
Delwyn G Fredlund
Keyword(s):  
Numerical Modelling ◽  
Volume Change ◽  
Void Ratio ◽  
Expansive Soils ◽  
Ground Surface ◽  
Expansive Soil ◽  
Coupled Analysis ◽  
Coupled Equations ◽  
Mathematical Equations ◽  
Unsaturated Expansive Soils

There are challenges associated with the numerical modelling of unsaturated expansive soils. The challenges are primarily related to the quantification of the void ratio constitutive surface, the characterization of the void ratio constitutive surface at low stresses and (or) suction, and the solution of coupled equations with several nonlinear unsaturated soil property functions. This study suggests that the void ratio constitutive surface of an expansive soil subject to a monotonic wetting path can be estimated from volume change indices obtained from conventional laboratory tests. The constitutive surfaces for both the soil structure and the water phase can be described using mathematical equations that allow net normal stress and suction to be reduced to zero. The solutions for two typical volume change problems are presented using both a coupled approach and an uncoupled approach. The first example problem simulates water leakage from a pipe under a flexible cover. The second example problem simulates the infiltration of water at ground surface. The results of the analyses are in accordance with anticipated behaviour. The results also show that the answers from an uncoupled analysis compared well with those from a coupled analysis. It is suggested that an uncoupled analysis may be adequate for most prediction of heave problems involving unsaturated expansive soils.Key words: heave prediction, numerical modelling, expansive soil, constitutive surface, uncoupled analysis, matric suction.

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