Surrounding Soil Medium Research Articles

Investigation of Thermal Energy Accumulation Using Soil Layer for Buildings’ Energy Efficiency

The cold climate countries require high energy consumption for buildings’ heating. According to EU directives and national law, buildings’ energy efficiency is increasing due to higher investment in the sector. Primary energy consumption for space heating still comprises a large part of global energy consumption. It is essential to develop technological solutions and innovations to reduce energy consumption by using newer, smarter, more natural energy generation and accumulation. The soil layer could be used as a natural material for thermal energy accumulation. The soil’s temperature is higher than atmospheric air in the heating season and is lower in the non-heating season. Underground buildings placed in a soil medium could use less thermal energy for buildings’ heating and cooling during its life cycle. The impact of the wind is eliminated in this underground building case. As the soil temperature rises, the difference in temperature of the building’s inside air and the soil decreases. This means that the heat loss into the soil generates the conditions acting against the heat loss. However, heat spreads further and dissipates in the surrounding soil medium. The analysis of this research results showed that the savings in energy could reach 28 percent in the case of the underground building. Heat loss to the soil could be treated as the charge of the soil by thermal energy. The charging by heat and heat dissipation in the soil was researched experimentally. The dependence of the intensity of the charge on time was analysed and presented in this paper also.

Analytical Solution of Laterally Loaded Free-Head Long Piles in Elasto-Plastic Cohesive Soils

This research study presents a closed form solution of responses of laterally loaded long piles embedded on cohesive soils with a constant subgrade modulus. The surrounding soil medium is modelled as elastic-perfectly plastic. The closed form solution is derived by solving the governing differential equation of the pile–soil system. The most popular numerical computation software package MATLAB is utilized for the implementation of solutions. The provided analytical method reliably calculates the pile head deflection and bending moment required for engineering design purposes. Results are discussed and verified with solutions of an equivalent three-dimensional finite element (FE) model developed using ANSYS software. It was concluded that the proposed analytical model could efficiently provide the exact solution of embedded piles in elasto-plastic cohesive soil under lateral loads.

Effect of application factors on optimum design of reinforced concrete retaining systems

Retaining walls and cantilever soldier pile walls are both can be used in interchangeable manner so it is so important to evaluate the relationship between the cost and sizing. In this paper, an investigation of the effect of the design restraints and cost limits of both reinforced concrete retaining walls and cantilever soldier pile walls on optimum design is done. Pure frictional soils are evaluated as the surrounding soil medium of retaining structures and Rankine lateral earth pressure theory is used to derive the lateral thrust effected through the selected retaining systems. Fictionalized different cases are created for all retaining systems to compare optimal dimensions and minimum costs for the same project requirements. Jaya algorithm is used to perform optimization process. Parametrical analyses are conducted according to change of excavation depth, unit weight of soil, and cost of concrete, surcharge load and workmanship multiplier. The results of the parametric analysis has provided to suggest on the design and application differences of both retaining systems having regard to the effects of both cost and sizing simultaneously. As a consequence of the study, some limitations that have to be considered before design are given for the selection of proper retaining structure not to cause overinvestment.

Elastic-slip interface effect on dynamic response of underwater convey tunnel in saturated poroelastic soil subjected to plane waves

In engineering construction, the elastic-slip interface often exists around the tunnel. An elastic-slip interface model is proposed to analyze the dynamic response of underwater convey tunnel, and the surrounding soil is assumed to be saturated poroelastic medium. The reflected, refracted and scattered waves in the free surface water, the surrounding soil medium and the tunnel are expressed by wave function expansion method. Based on Biot’s dynamic theory, an elastic-slip interface is developed to analyze the scattering of P and SV waves around the tunnel. The interface coefficients (normal and tangential spring coefficients and slip coefficient) are introduced to analyze the elastic-slip interface effect on the dynamic stresses under different wave frequencies. It can be concluded that the effect of normal spring coefficient is greater than that of tangential spring coefficients. The interface effect in the region of low frequency is greater than that of high frequency. The interface effect under different surface water depths and embedded depths of tunnel is also examined. Comparison with existing numerical results validates this dynamic model.

Plant root penetration and growth as a mechanical inclusion problem

The ability of plant roots to penetrate soils is affected by several stimuli exerted by the surrounding medium, such as mechanical stresses and chemical stimuli. Roots have developed different adaptive responses, such as increase or decrease of the elongation rate of the apical region and swelling or shrinking of its diameter. We propose a mathematical model aimed at explaining the dynamic evolution of plant roots during the penetration into the soil. We treat the root as a cylinder and the root–soil interaction as a purely mechanical inclusion problem. In particular, the root dynamic evolution is based on a modified version by one of the authors of the extended universal law of West, Brown, and Enquist. Coupling the solution of the mechanical problem and the growth equation, we compare the theoretical results with experimental data collected in artificial and real soils. In this work, we propose a plausible interpretation of the experimental results of the root behavior during the growth inside the surrounding soil medium.

Flexible oneanchor retaining building models calculation results comparing with experimental data

Based on the previously described mathematical model implemented in software complex PLASTICA, nonlinear calculation of one anchor sheet pile wall together with surrounding soil medium has been performed. To assess the results reliability with experimental data tests Lazebnik G.E., calculations in PLAXIS 2D and classic Coulomb method are compared. The basis of a mathematical model incorporated the theory of plastic flow with hardening, which is based on the principle of maximum Mises. In general, it can be assumed that the calculations results in the software package PLASTICA using the proposed nonlinear models showed satisfactory agreement as compared with the experimental data

Detecting changes in sediment overburden using distributed temperature sensing: an experimental and numerical study

Fibre optic cables can be used as sensors to monitor temperature changes through the analysis of back scattered light. This can be linked to changes in the ambient conditions surrounding the fibre optic cable. Active distributed temperature sensing relies on an external heat source relative to the fibre optic cable to measure the properties of, and changes in, the surrounding medium. An experiment was conducted using distributed temperature sensing technology to monitor changes in sediment overburden for the purpose of determining whether scour could be measured above buried power cables containing fibre optic cables. Fibre optic cables were buried in a channel containing saturated sand and water with an external heat source. The depth of overburden sediment above the fibre optic cables was reduced, whilst the associated temperature response along the fibre optic cable was monitored. The data was matched to a finite element model so that the heat transfer taking place could be simulated and then the thermal conductivity of the soil modified to observe the potential changes in heat detected by the fibre optic cables. This paper explains the characteristics of heat transfer from an active heat source to the surrounding soil medium providing a means to translate the temperature measurement to the associated overburden thickness and to model the same response in different materials.

Dynamic response of nanoparticle-water pipes buried in the soil subjected to far-fault earthquake using numerical method

Presenting a mathematical model for seismic response of the water pipes buried in the soil is the main contribution of this study. The structure is subjected to far-fault earthquake load. The pipe is conveying water mixed by nanoparticles where the Navier–Stokes equation is used for considering the interaction of fluid and pipe. The surrounding soil medium is simulated by spring elements. Utilizing the cylindrical shell element, the pipe is modeled mathematically and the motion equation of the structure is derived by Hamilton's principal. Based on Galerkin and Newmark methods, the dynamic deflection of the structure is calculated. The effects of different parameters such as fluid velocity, soil medium, volume percent of nanoparticle in fluid, boundary condition and geometrical parameters of the pipe are shown on the dynamic deflection of the structure. Numerical results indicate that water pipe buried in the solid has lower dynamic deflection with respect to the pipe without soil foundation.

Effect of Soil Layering on Coupled Dynamic Response and Active Length of Piles Embedded in Layered Soil Using Cone Model

Dynamic analysis of single pile embedded in two-layered soil has been performed to study the influence of layering on the frequency dependent displacement response and active length under coupled horizontal and rocking vibration. Cone model has been used to determine the dynamic stiffness coefficient of pile. The soil and pile has been assumed to behave as elastic during dynamic loading. It has been also assumed that perfect bond exists between pile surface and surrounding soil medium. The wave generated due to pile vibration transfer to the soil through soil–pile interface and propagates to the infinity. The wave propagation has been modeled with cone model and soil–pile interaction has been incorporated through beam equation. The dynamic response of the pile obtained from the analysis has been plotted against non dimensional frequency to investigate the behavior of pile under such loading condition. The horizontal displacement profile along the depth of pile has been studied for different top layer thickness and homogeneous soil. The results showed that dynamic response is very sensitive to the thickness of the top layer and its properties. The active length of pile increases with the increase in top layer thickness.

Numerical analysis of internal blast effects on underground tunnel in soils

The response of underground structures subjected to internal blasts is an important topic in protective engineering. Due to various constraints, pertinent experimental data are extremely scarce. Adequately detailed numerical simulation thus becomes a desirable alternative. However, the physical processes involved in the internal explosion and blast wave propagation are very complex, and hence, a realistic and detailed reproduction of the phenomena would require sophisticated numerical models for the loading and material responses. In this article, a fully coupled numerical model is established to simulate dynamic responses of tunnel structure in soils under internal blasting loads. The approach considers all the stages of the process: detonation of the internal charge; shock wave propagation in the internal gas; coupled fluid–structure interaction between explosive wave and tunnel structure; structure damage; soil–structure dynamic interaction; and wave propagation in the surrounding soil medium. Effects of soil–structure interactions, soil stiffnesses, buried depths, cross-sectional shapes and locations of charge are thoroughly investigated on dynamic responses of tunnel structures subjected to internal blasting loads. Results show that the tunnel responses are driven by the soil stiffness rather than by the interface friction, and the location of charge has a significant effect on the tunnel responses.

The effect of an explosion in a tunnel on a neighboring buried structure

A comprehensive approach to simulate the effects of an explosion occurring inside a buried infrastructure tunnel on the soil surface and on nearby tunnels is presented. The approach considers all the stages of the complex process: detonation of the internal explosive charge; the shock wave propagation through the air in the tunnel and its following interaction with the cavity’s lining; it then examines the soil-structure dynamic interaction, including wave propagation in the surrounding soil medium and their interaction with the nearby tunnels. The soil model takes into account both bulk and shear elastic plastic behavior, including the effect of the soil pressure on the yield strength for the stress tensor deviator. The variational-difference method is applied to solve the problem in the soil and in the lining domains. The developed approach allows studying the effect of the soil and lining properties on the soil-tunnel interaction as well as the explosion effect on a nearby tunnel behavior and on the soil surface response.

Seismic isolation effect of lined circular tunnels with damping treatments

The Havriliak-Negami model for dynamic viscoelastic material behavior and Biot’s theory of poroelasticity are employed to develop an exact solution for three-dimensional scattering effect of harmonic plane P-SV waves from a circular cavity lined with a multilayered fluid-filled shell of infinite length containing viscoelastic damping materials and embedded within a fluid-saturated permeable surrounding soil medium. The analytical results are illustrated with numerical examples where the effects of liner/coating structural arrangement, viscoelastic material properties, liner-soil interface bonding condition, seismic excitation frequency, and angle of incidence on the induced dynamic stress concentrations are evaluated and discussed to obtain representative values of the parameters that characterize the system. It is demonstrated that incorporating viscoelastic damping materials with a low shear modulus in the constrained layer configuration is an efficient means of enhancing the overall seismic isolation performance, especially for near-normally incident seismic shear waves where the amplitudes of induced dynamic stresses may be reduced by up to one-third of those without isolation in a relatively wide frequency range. Some additional cases are considered and good agreements with solutions available in the literature are obtained.

Dynamic response analysis of a building structure subjected to ground shock from a tunnel explosion

Dynamic responses of a multi-storey building without or with a sliding base-isolation device to ground shock induced by an in-tunnel explosion are numerically analyzed in this paper. The effect of an adjacent tunnel in between the building and the explosion tunnel, which affects ground shock propagation, is also considered in the analysis. Different modeling methods, such as the eight-node iso-parametric finite element and mass-lumped system, are used to establish the coupling model consisting of the two adjacent tunnels, the surrounding soil medium with the Lysmer viscous boundary condition and the multi-storey building with or without the sliding base-isolation device. In numerical calculations, a continuous friction model, which is different from the traditional Coulomb friction model, is adopted to improve the computational efficiency and reduce the accumulated errors. Some example analyses are subsequently performed to study the response characteristics of the building and the sliding base-isolation device to ground shock. The effect of the adjacent tunnel in between the building and the explosion tunnel on the ground shock wave propagation is also investigated in the study. The final conclusions based on the numerical results will provide some guidance in engineering practice.

Buried Pipelines Subject to Subgouge Deformations

Engineers often model pipe/soil interaction events based on the concept of subgrade reactions originally proposed by Winkler. Engineering models often utilize beam and nonlinear/plastic spring elements to represent pipelines and the surrounding soil medium, respectively. The spring formulations, defining soil resistance to deformations in three-dimensional space, are usually assumed to be independent and the responses are discrete between adjacent soil zones. However, this idealization does not truly replicate a soil medium behavior. This study presents coupled numerical analyses of pipeline for the specific problem of subgouge deformations due to ice gouge events. Three dimensional continuum analyses of coupled pipe/soil/ice keel interaction using an explicit arbitrary Lagrangian finite- element approach were performed. The study compares the continuum finite-element results with Winkler-type analysis for the specific analyzed problem. A Lagrangian adaptive meshing technique was employed to model very la...

Prediction and validation of traffic vibration reduction due to cement column stabilization

The transmission and reduction of vibrations in the far-field of the surface of the ground due to a surface load is investigated theoretically and validated with given field measurement data. The performance of a given stabilization column, located directly underneath the load, at a number of receiver positions is studied and measured in terms of insertion loss. A numerical model is presented, which enables the wave-field in the region of the column to be determined, based on an integral equation formulation of the problem which is solved using a boundary element approach. It is shown that the column has a beneficial effect at low frequencies especially in certain frequency bandwidths and is validated with field data. However, when the Rayleigh wavelength becomes short compared with the depth and width of the column adverse effects occur at some frequencies which are also observed in the far-field. Various depths of columns and material properties of the surrounding soil medium are studied and results presented so that some preliminary physical conclusions may be derived.

Hydrogen isotope fractionation during water uptake by woody xerophytes

Stable isotope measurements are employed extensively in plant–water relations research to investigate physiological and hydrological processes from whole plant to ecosystem scales. Stable isotopes of hydrogen and oxygen are routinely measured to identify plant source water. This application relies on the assumption that no fractionation of oxygen and hydrogen isotopes in water occurs during uptake by roots. However, a large fraction of the water taken up through roots in halophytic and xerophytic plants transverses cell membranes in the endodermis before entering the root xylem. Passage of water through this symplastic pathway has been hypothesized to cause fractionation leading to a decrease in 2H of root xylem water relative to that in the surrounding soil medium. We examined 16 woody halophytic and xerophytic plant species in controlled conditions for evidence of hydrogen isotope fractionation during uptake at the root–soil interface. Isotopic separation (Δ2H = δ2Hsoil water − δ2Hxylem water) ranging from 3‰ to 9‰ was observed in 12 species. A significant positive correlation between salinity tolerance and the magnitude of Δ2H was observed. Water in whole stem segments, sapwood, and roots had significantly lower δ2H values relative to soil water in Prosopis velutina Woot., the species expressing the greatest Δ2H values among the 16 species examined. Pressurized water flow through intact root systems of Artemisia tridentata Nutt. and Atriplex canescens (Pursh) Nutt. caused the δ2H values to decrease as flow rate increased. This relationship was not observed in P. velutina. Destroying the plasma membranes of root cells by excessive heat from boiling did not significantly alter the relationship between δ2H of expressed water and flow rate. In light of these results, care should be taken when using the stable isotope method to examine source-water use in halophytic and xerophytic species.

Seismic analysis of underground reinforced concrete structures considering elasto-plastic interface element with thickness

Since underground reinforced concrete (RC) structures interact with the surrounding soil medium, the behavior of the interfacial zone between the RC structure and the surrounding medium of the underground RC structure should be considered for accurate seismic analysis. In this paper, an averaged constitutive model of concrete and reinforcing bars for the RC structure and the path-dependent Ohsaki’s model for the soil are applied, and an elasto-plastic interface model which considers the thickness of the interface is proposed for seismic analysis of underground RC structures. A finite element analysis program is developed and verified by predicting both static and dynamic behaviors of underground RC structures. Then, the effects of the interface on the behavior of underground RC structures are analyzed. The effect of stiffness of the RC structure due to different reinforcement ratios of underground RC box structures to the behavior of the structures is also analyzed. Finally, failure mechanisms of underground RC structure under seismic action are simulated through seismic analysis of an underground RC station structure.

유한요소법을 이용한 철근콘크리트 지하철 정거장 구조물의 내진 해석

Even though a lot of advanced researches on analysis, design, and performance evaluation of reinforced concrete (RC) under seismic action have been carried out, there has been only a few study on seismic analysis of underground RC structures surrounding soil medium. Since the underground RC structures interact with surrounding soil medium, a path-dependent soil model which can predict the soil response is necessary for analyzing behavior of the structure inside soil medium. The behavior of interfacial zone between the RC structure and the surrounding medium should be also considered for more accurate seismic analysis of the RC structure. In this paper, an averaged constitutive model of concrete and reinforcing bars for RC structure and path-dependent Ohsaki's model for soil are applied, and an elasto-plastic interface model having thickness is proposed for seismic analysis of underground RC structures. A finite element analysis technique is developed by applying aforementioned constitutive equations and is verified by predicting both static and dynamic behaviors of RC structures. Then, failure mechanisms of underground RC structure under seismic action are numerically derived through seismic analysis of underground RC station structure under different seismic forces. Finally, the changes of failure mode and the damage level of the structures are also analytically derived for different design cases of underground RC structures.

MODELLING OF NONLINEAR DYNAMIC BEHAVIOUR OF A SHALLOW STRIP FOUNDATION WITH MACRO-ELEMENT

A new nonlinear soil-structure interaction macroelement is presented. It models the dynamic behaviour of a shallow strip foundation under seismic action. Based on sub-structured methods, it takes into account the dynamic elastic effect of the infinite far field, and the material and geometrical nonlinear behaviour produced in the near field of the foundation. Effects of soil yielding below the foundation as well as uplift at the interface are considered. Through the concept of macro-element, the overall elastic and plastic behaviour in the soil and at the interface is reduced to its action on the foundation. The macro-element consists of a non linear joint element, expressed in the three degrees of freedom of the strip foundation, reflecting the limited bearing capacity of the foundation. This model provides a practical and efficient tool to study the seismic response of a structure in interaction with the surrounding soil medium. Applications to a bridge pier show the potentialities of this kind of model.

Corrosion of Reinforcing Steel in Drilled Shafts with Construction Flaws

The construction process for drilled shafts sometimes introduces structural flaws such as voids or soil inclusions within the shaft. In that case, the reinforcing steel loses concrete cover and comes in contact with the surrounding soil medium, which creates a favorable environment for corrosion. Corrosion of steel inside concrete, as well as in soil media, has been investigated in the literature. However, the specific case of steel passing through different media (concrete and soil) simultaneously has received little attention. The results of an experimental program designed to investigate the effect of two different media of substantially different pH values on the rate of corrosion of steel reinforcement in sand and clay soils and with different anode-to-cathode-area ratios are presented. Preliminary results suggest that galvanic currents driven by dissimilar media could increase the corrosion rate of exposed steel by 3.3 to 5.6 times, particularly in environments with otherwise low corrosion potential.