Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 1728

Search results for: unsaturated zone

1728 Modelling Interactions between Saturated and Unsaturated Zones by Hydrus 1D, Plain of Kairouan, Central Tunisia

Authors: Mariem Saadi, Sabri Kanzari, Adel Zghibi

Abstract:

In semi-arid areas like the Kairouan region, the constant irrigation with saline water and the overuse of groundwater resources, soils and aquifers salinization has become an increasing concern. In this study, a methodology has been developed to evaluate the groundwater contamination risk based on the unsaturated zone hydraulic properties. Two soil profiles with different ranges of salinity, one located in the north of the plain and another one in the south of plain (each 30 m deep) and both characterized by direct recharge of the aquifer were chosen. Simulations were conducted with Hydrus-1D code using measured precipitation data for the period 1998-2003 and calculated evapotranspiration for both chosen profiles. Four combinations of initial conditions of water content and salt concentration were used for the simulation process in order to find the best match between simulated and measured values. The success of the calibration of Hydrus-1D allowed the investigation of some scenarios in order to assess the contamination risk under different natural conditions. The aquifer risk contamination is related to the natural conditions where it increased while facing climate change and temperature increase and decreased in the presence of a clay layer in the unsaturated zone. Hydrus-1D was a useful tool to predict the groundwater level and quality in the case of a direct recharge and in the absence of any information related to the soil layers except for the texture.

Keywords: Hydrus-1D, Kairouan, salinization, semi-arid region, solute transport, unsaturated zone

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1727 Matric Suction Effects on Behavior of Unsaturated Soil Slope

Authors: Mohsen Mousivand, Hesam Aminpour

Abstract:

Soil slopes are usually located above the groundwater level that are largely unsaturated. It is possible that unsaturated soil of slope has expanded or collapsed as a result of wetting by rain or other factor that this type of soil behavior can cause serious problems including human and financial damage. The main factor causing this difference in behavior of saturated and unsaturated state of soil is matric suction that is created by interface of the soil and water in the soil pores. So far theoretical studies show that matric suction has important effect on the mechanical behavior of soil although the impact of this factor on slope stability has not been studied. This paper presents a numerical study of effect of matric suction on slope stability. The results of the study indicate that safety factor and stability of soil slope increase due to an increasing of matric suction and in view of matric suction leads to more accurate results and safety factor.

Keywords: slope, unsaturated soil, matric suction, stability

Procedia PDF Downloads 287
1726 Prediction of Permeability of Frozen Unsaturated Soil Using Van Genuchten Model and Fredlund-Xing Model in Soil Vision

Authors: Bhavita S. Dave, Jaimin Vaidya, Chandresh H. Solanki, Atul K.

Abstract:

To measure the permeability of a soil specimen, one of the basic assumptions of Darcy's law is that the soil sample should be saturated. Unlike saturated soils, the permeability of unsaturated soils cannot be found using conventional methods as it does not follow Darcy's law. Many empirical models, such as the Van Genuchten Model and Fredlund-Xing Model were suggested to predict permeability value for unsaturated soil. Such models use data from the soil-freezing characteristic curve to find fitting parameters for frozen unsaturated soils. In this study, soil specimens were subjected to 0, 1, 3, and 5 freezing-thawing (F-T) cycles for different degrees of saturation to have a wide range of suction, and its soil freezing characteristic curves were formulated for all F-T cycles. Changes in fitting parameters and relative permeability with subsequent F-T cycles are presented in this paper for both models.

Keywords: frozen unsaturated soil, Fredlund Xing model, soil-freezing characteristic curve, Van Genuchten model

Procedia PDF Downloads 150
1725 Prediction of Unsaturated Permeability Functions for Clayey Soil

Authors: F. Louati, H. Trabelsi, M. Jamei

Abstract:

Desiccation cracks following drainage-humidification cycles. With water loss, mainly due to evaporation, suction in the soil increases, producing volumetric shrinkage and tensile stress. When the tensile stress reaches tensile strength, the soil cracks. Desiccation cracks networks can directly control soil hydraulic properties. The aim of this study was for quantifying the hydraulic properties for examples the water retention curve, the saturated hydraulic conductivity, the unsaturated hydraulic conductivity function, the shrinkage dynamics in Tibar soil- clay soil in the Northern of Tunisia. Then a numerical simulation of unsaturated hydraulic properties for a crack network has been attempted. The finite elements code ‘CODE_BRIGHT’ can be used to follow the hydraulic distribution in cracked porous media.

Keywords: desiccation, cracks, permeability, unsaturated hydraulic flow, simulation

Procedia PDF Downloads 259
1724 Mechanical Properties of Palm Oil-Based Resin Containing Unsaturated Polyester

Authors: Alireza Fakhari, Abdul Razak Rahmat

Abstract:

In this study, new palm oil-based polymer systems have been produced by blending unsaturated polyester (UPE) and maleinated, acrylated epoxidized palm oil (MAEPO). The MAEPO/UPE ratio was varied between 10/90 and 40/60 wt%. The influences of various loadings of MAEPO (10, 20, 30, and 40 wt%) on tensile, flexural and impact properties of resulting polymer systems were investigated. The results revealed that, these bio-based polymer systems exhibit mechanical properties comparable to those of petroleum-based polymers.

Keywords: palm oil, bio-based resin, renewable resources, unsaturated polyester resin

Procedia PDF Downloads 293
1723 Determination of Suction of Arid Region Soil Using Filter Paper Method

Authors: Bhavita S. Dave, Chandresh H. Solanki, Atul K. Desai

Abstract:

Soils of Greater Himalayas mostly pertain to Leh & Ladakh, Lahaul & Sppiti, & high reaches to Uttarakhand. The moisture regime is aridic. The arid zone starts from Baralacha pass in Lahaul and covers the entire Spiti valley in the district of Lahaul & Spiti, Himachal Pradesh of India. Here, the present study is an attempt to determine the suction value of soil collected from the arid zone of Spiti valley for different freezing-thawing cycles considering the climate ranges of Spiti valley. Suction is the basic and most important parameter which influences the behavior of unsaturated soil. It is essential to determine the suction value of unsaturated soil before other tests like shear test, and permeability. Basically, it is the negative pore water pressure in partially saturated soil measured in terms of the height of the water column. The filter paper method has been used for the study as an economical approach to evaluate suction. It is the only method from which both contact and non-contact suction can be deduced. In this study, soil specimens were subjected to 0, 1, 3, & 5 freezing-thawing (F-T) cycles for different degrees of saturation to have a wide range of suction, and soil freezing characteristic curves (SFCC) were formulated for all F-T cycles. The result data collected from the experiments have shown best-fitted values using Fredlund & Xing model for each SFCC.

Keywords: suction, arid region soil, soil freezing characteristic curve, freezing-thawing cycle

Procedia PDF Downloads 186
1722 Institutional Superposition, over Management and Coastal Economic Development: Coastal Areas in China

Authors: Mingbao Chen, Mingli Zhao

Abstract:

The coastal zone is the intersection of land and sea system, and also is the connecting zone of the two economic systems of land and sea. In the world, all countries attach great importance to the coastal zone management and the coastal zone economy. In China, the government has developed a number of related coastal management policies and institutional, such as marine functional zoning, main function zoning, integrated coastal zone management, to ensure the sustainable utilization of the coastal zone and promote the development of coastal economic. However, in practice, the effect is not satisfactory. This paper analyses the coastal areas of coastal zone management on coastal economic growth contribution based on coastal areas economic development data with the 2007-2015 in China, which uses the method of the evaluation index system of coastal zone management institutional efficiency. The results show that the coastal zone management institutional objectives are not clear, and the institutional has high repeatability. At the same time, over management of coastal zone leads to low economic efficiency because the government management boundary is blurred.

Keywords: institutional overlap, over management, coastal zone management, coastal zone economy

Procedia PDF Downloads 343
1721 Calibration of Resistance Factors for Reliability-Based Design of Driven Piles Considering Unsaturated Soil Effects

Authors: Mohammad Amin Tutunchian, Pedram Roshani, Reza Rezvani, Julio Ángel Infante Sedano

Abstract:

The highly recommended approach to design, known as the load and resistance factor design (LRFD) method, employs the geotechnical resistance factor (GRF) for shaping pile foundation designs. Within the standard process for designing pile foundations, geotechnical engineers commonly adopt a design strategy rooted in saturated soil mechanics (SSM), often disregarding the impact of unsaturated soil behavior. This oversight within the design procedure leads to the omission of the enhancement in shear strength exhibited by unsaturated soils, resulting in a more cautious outcome in design results. This research endeavors to present a methodology for fine-tuning the GRF used for axially loaded driven piles in Winnipeg, Canada. This is achieved through the application of a well-established probabilistic approach known as the first-order second moment (FOSM) method while also accounting for the influence of unsaturated soil behavior. The findings of this study demonstrate that incorporating the influence of unsaturated conditions yields an elevation in projected bearing capacity and recommends higher GRF values in accordance with established codes. Additionally, a novel factor referred to as phy has been introduced to encompass the impact of saturation conditions in the calculation of pile bearing capacity, as guided by prevalent static analysis techniques.

Keywords: unsaturated soils, shear strength, LRFD, FOSM, GRF

Procedia PDF Downloads 37
1720 Influence of Rainfall Intensity on Infiltration and Deformation of Unsaturated Soil Slopes

Authors: Bouziane Mohamed Tewfik

Abstract:

In order to improve the understanding of the influence of rainfall intensity on infiltration and deformation behaviour of unsaturated soil slopes, numerical 2D analyses are carried out by a three phase elasto-viscoplastic seepage-deformation coupled method. From the numerical results, it is shown that regardless of the saturated permeability of the soil slope, the increase in the pore water pressure (reduction in suction) during rainfall infiltration is localized close to the slope surface. In addition, the generation of the pore water pressure and the lateral displacement are mainly controlled by the ratio of the rainfall intensity to the saturated permeability of the soil.

Keywords: unsaturated soil, slope stability, rainfall infiltration, numerical analysis

Procedia PDF Downloads 424
1719 Laboratory Study on Behavior of Compacted Soils

Authors: M. M. Mekkakia, M. P Luong, A. Arab

Abstract:

These controlling the water content of compaction are a major concern of fundamental civil engineers. Also, the knowledge of the fundamentals of the behaviour of compacted clay soils is essential to predict and quantify the effects of a change in water content. The study of unsaturated soils is a very complex area which several studies are directed to in recent years. Our job work is to perform tests of Proctor, Oedometer and shear, on samples of unsaturated clay in order to see the influence of water content on the compressibility and the shear strength. The samples were prepared at different amounts of water from water content to optimum water contents close to saturation. This study thus allowed us to measure and monitor the parameters of compressibility and shear strength as a function of water content.

Keywords: laboratory tests, clay, unsaturated soil, atterberg limits, compaction, compressibility, shear

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1718 Rock Property Calculation for Determine Hydrocarbon Zone Based on Petrophysical Principal and Sequence Stratigraphic Correlation in Blok M

Authors: Muhammad Tarmidzi, Reza M. G. Gani, Andri Luthfi

Abstract:

The purpose of this study is to identify rock zone containing hydrocarbons with calculating rock property includes volume shale, total porosity, effective porosity and water saturation. Identification method rock property based on GR log, resistivity log, neutron log and density rock. Zoning is based on sequence stratigraphic markers that are sequence boundary (SB), transgressive surface (TS) and flooding surface (FS) which correlating ten well log in blok “M”. The results of sequence stratigraphic correlation consist of eight zone that are two LST zone, three TST zone and three HST zone. The result of rock property calculation in each zone is showing two LST zone containing hydrocarbons. LST-1 zone has average volume shale (Vsh) 25%, average total porosity (PHIT) 14%, average effective porosity (PHIE) 11% and average water saturation 0,83. LST-2 zone has average volume shale (Vsh) 19%, average total porosity (PHIT) 21%, average effective porosity (PHIE) 17% and average water saturation 0,82.

Keywords: hydrocarbons zone, petrophysic, rock property, sequence stratigraphic

Procedia PDF Downloads 264
1717 Effect of Subsequent Drying and Wetting on the Small Strain Shear Modulus of Unsaturated Soils

Authors: A. Khosravi, S. Ghadirian, J. S. McCartney

Abstract:

Evaluation of the seismic-induced settlement of an unsaturated soil layer depends on several variables, among which the small strain shear modulus, Gmax, and soil’s state of stress have been demonstrated to be of particular significance. Recent interpretation of trends in Gmax revealed considerable effects of the degree of saturation and hydraulic hysteresis on the shear stiffness of soils in unsaturated states. Accordingly, the soil layer is expected to experience different settlement behaviors depending on the soil saturation and seasonal weathering conditions. In this study, a semi-empirical formulation was adapted to extend an existing Gmax model to infer hysteretic effects along different paths of the SWRC including scanning curves. The suitability of the proposed approach is validated against experimental results from a suction-controlled resonant column test and from data reported in literature. The model was observed to follow the experimental data along different paths of the SWRC, and showed a slight hysteresis in shear modulus along the scanning curves.

Keywords: hydraulic hysteresis, scanning path, small strain shear modulus, unsaturated soil

Procedia PDF Downloads 344
1716 Numerical Simulations of Frost Heave Using COMSOL Multiphysics Software in Unsaturated Freezing Soils

Authors: Sara Soltanpour, Adolfo Foriero

Abstract:

Frost heave is arguably the most problematic adverse phenomenon in cold region areas. Frost heave is a complex process that depends on heat and water transfer. These coupled physical fields generate considerable heave stresses as well as deformations. In the present study, a coupled thermal-hydraulic-mechanical (THM) model using COMSOL Multiphysics in frozen unsaturated soils, such as fine sand, is investigated. Particular attention to the frost heave and temperature distribution, as well as the water migrating during soil freezing, is assessed. The results obtained from the numerical simulations are consistent with the results measured in the full-scale tests conducted by Cold Regions Research and Engineering Laboratory (CRREL).

Keywords: frost heave, numerical simulations, COMSOL software, unsaturated freezing soil

Procedia PDF Downloads 68
1715 The Conceptual Exploration of Comfort Zone by Using Content Analysis

Authors: Lilla Szabó Hangya, Szilvia Jambori

Abstract:

The comfort zone is less studied area in the field of psychology. One of the most important definitions is that comfort zone is a psychological state in which things feel familiar to a person with low level of anxiety and stress. But the validity of comfort zone does not confirm till now. The aim of our pilot research is to test which psychological factors could determine how young adults behave during their decision process to stay in one’s comfort zone or to leave it. Every person has a number of comfort zones, so we are not able to measure it directly, only those personality traits which predict if someone leaves his comfort zone easier or harder. In our study at first we wanted to clarify the meaning of comfort zone. 110 young adults (male: 37, female: 73; ages from 18 to 70, average age: 26,6) took part in the study. Beside their demographic datas we asked them what does the comfort zone mean for them. The results showed that the meaning of the comfort zone can be grouped in five dimensions: comfort (49,6 %), leaving it-change (8,1%), ambivalent feelings (10,6%), related to other people (10,6%), pursuit of self-realization (16,8%). Our results demonstrated age related characteristics. For young people at the age of 19 the comfort zone is related to other people, because during adolescents peer relationships become more important. Subjects at the age 20-30 answered that the comfort zone means comfort and stability for them. Their life becomes stable for a while, they are studying or working. But at the age of 25, when they finish university, most of them answered comfort zone means a changing process for them. On the other hand for subjects at the age of 27 the means of the comfort zone is pursuit of self-realization. After that period at the age of 31 when they have families and stable job the stability will also dominant. We saw that the comfort zone has much more meaning besides a pleasant psychological trait. Further we would like to determine which psychological factors relate to comfort zone, and what kind of personality traits could predict leaving or staying in one’s comfort zone. We want to observe the relationship between comfort zone and subjective well-being, life satisfaction self-efficacy or self-esteem.

Keywords: comfort zone, development, personality trait, young adults

Procedia PDF Downloads 300
1714 Effect of Filter Paper Technique in Measuring Hydraulic Capacity of Unsaturated Expansive Soil

Authors: Kenechi Kurtis Onochie

Abstract:

This paper shows the use of filter paper technique in the measurement of matric suction of unsaturated expansive soil around the Haspolat region of Lefkosa, North Cyprus in other to establish the soil water characteristics curve (SWCC) or soil water retention curve (SWRC). The dry filter paper approach which is standardized by ASTM, 2003, D 5298-03 in which the filter paper is initially dry was adopted. The whatman No. 42 filter paper was used in the matric suction measurement. The maximum dry density of the soil was obtained as 2.66kg/cm³ and the optimum moisture content as 21%. The soil was discovered to have high air entry value of 1847.46KPa indicating finer particles and 25% hydraulic capacity using filter paper technique. The filter paper technique proved to be very useful for measuring the hydraulic capacity of unsaturated expansive soil.

Keywords: SWCC, matric suction, filter paper, expansive soil

Procedia PDF Downloads 129
1713 Investigation of Corrosion of Steel Buried in Unsaturated Soil in the Presence of Cathodic Protection: The Modified Voltammetry Technique

Authors: Mandlenkosi G. R. Mahlobo, Peter A. Olubambi, Philippe Refait

Abstract:

The aim of this study was to use voltammetry as a method to understand the behaviour of steel in unsaturated soil in the presence of cathodic protection (CP). Three carbon steel coupons were buried in artificial soil wetted at 65-70% of saturation for 37 days. All three coupons were left at open circuit potential (OCP) for the first seven days in the unsaturated soil before CP, which was only applied on two of the three coupons at the protection potential -0.8 V vs Cu/CuSO₄ for the remaining 30 days of the experiment. Voltammetry was performed weekly on the coupon without CP, while electrochemical impedance spectroscopy (EIS) was performed daily to monitor and correct the applied CP potential from the ohmic drop. Voltammetry was finally performed on the last day on the coupons under CP. All the voltammograms were modeled with mathematical equations in order to compute the electrochemical parameters and subsequently deduced the corrosion rate of the steel coupons. For the coupon without CP, the corrosion rate was determined at 300 µm/y. For the coupons under CP, the residual corrosion rate under CP was estimated at 12 µm/y while the corrosion rate of the coupons, after interruption of CP, was estimated at 25 µm/y. This showed that CP was efficient due to two effects: a direct effect from the decreased potential and an induced effect associated with the increased interfacial pH that promoted the formation of a protective layer on the steel surface.

Keywords: carbon steel, cathodic protection, voltammetry, unsaturated soil, Raman spectroscopy

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1712 Utilization of Discarded PET and Concrete Aggregates in Construction Causes: A Green Approach

Authors: Arjun, A. D. Singh

Abstract:

The purpose of this study is to resolve the solid waste problems caused by plastics and concrete demolition as well. In order to that mechanical properties of polymer concrete; in particular, polymer concrete made of unsaturated polyester resins from recycled polyethylene terephthalate (PET) plastic waste and recycled concrete aggregates is carried out. Properly formulated unsaturated polyester based on recycled PET is mixed with inorganic aggregates to produce polymer concrete. Apart from low manufacturing cost, polymer concrete blend has acceptable properties, to go through it. The prior objectives of the paper is to investigate the mechanical properties, i.e. compressive strength, splitting tensile strength, and the flexural strength of polymer concrete blend using an unsaturated polyester resin based on recycled PET. The relationships between the mechanical properties are also analyzed.

Keywords: polyethylene terephthalate (PET), concrete aggregates, compressive strength, splitting tensile strength

Procedia PDF Downloads 526
1711 Communication Development for Development Communication: Prospects and Challenges of New Media Technologies in South East Zone, Nigeria

Authors: O. I. Ekwueme

Abstract:

New media technologies are noted for their immense contributions in various sectors of the economy which are believed to have resulted in the development of European countries. There is an assumption that we cannot have development communication without communication development, but we are not sure if new media technologies contribute to development in the South-East zone, Nigeria. The study employed mixed method and discovered that new media technologies have a very minimal relationship to development in the South-East zone, Nigeria. It was discovered that the media report on development news is basically informative instead of interactive. The South-East zone is scarcely covered unlike other zones. It argued that the communication technologies introduced in Nigeria was as a result of their struggle for independence. It was recommended that media organisations in the South-East zone should give adequate coverage to the zone, and be more interactive.

Keywords: communication, development, new media, technologies

Procedia PDF Downloads 289
1710 Solution to Riemann Hypothesis Critical Strip Zone Using Non-Linear Complex Variable Functions

Authors: Manojkumar Sabanayagam

Abstract:

The Riemann hypothesis is an unsolved millennium problem and the search for a solution to the Riemann hypothesis is to study the pattern of prime number distribution. The scope of this paper is to identify the solution for the critical strip and the critical line axis, which has the non-trivial zero solutions using complex plane functions. The Riemann graphical plot is constructed using a linear complex variable function (X+iY) and is applicable only when X>1. But the investigation shows that complex variable behavior has two zones. The first zone is the transformation zone, where the definition of the complex plane should be a non-linear variable which is the critical strip zone in the graph (X=0 to 1). The second zone is the transformed zone (X>1) defined using linear variables conventionally. This paper deals with the Non-linear function in the transformation zone derived using cosine and sinusoidal time lag w.r.t imaginary number ‘i’. The alternate complex variable (Cosθ+i Sinθ) is used to understand the variables in the critical strip zone. It is concluded that the non-trivial zeros present in the Real part 0.5 are because the linear function is not the correct approach in the critical strip. This paper provides the solution to Reimann's hypothesis.

Keywords: Reimann hypothesis, critical strip, complex plane, transformation zone

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1709 Investigation of Slope Stability in Gravel Soils in Unsaturated State

Authors: Seyyed Abolhasan Naeini, Ehsan Azini

Abstract:

In this paper, we consider the stability of a slope of 10 meters in silty gravel soils with modeling in the Geostudio Software.  we intend to use the parameters of the volumetric water content and suction dependent permeability and provides relationships and graphs using the parameters obtained from gradation tests and Atterberg’s limits. Also, different conditions of the soil will be investigated, including: checking the factor of safety and deformation rates and pore water pressure in drained, non-drained and unsaturated conditions, as well as the effect of reducing the water level on other parameters. For this purpose, it is assumed that the groundwater level is at a depth of 2 meters from the ground.  Then, with decreasing water level, the safety factor of slope stability was investigated and it was observed that with decreasing water level, the safety factor increased.

Keywords: slope stability analysis, factor of safety, matric suction, unsaturated silty gravel soil

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1708 Analytical Solution for Thermo-Hydro-Mechanical Analysis of Unsaturated Porous Media Using AG Method

Authors: Davood Yazdani Cherati, Hussein Hashemi Senejani

Abstract:

In this paper, a convenient analytical solution for a system of coupled differential equations, derived from thermo-hydro-mechanical analysis of three-phase porous media such as unsaturated soils is developed. This kind of analysis can be used in various fields such as geothermal energy systems and seepage of leachate from buried municipal and domestic waste in geomaterials. Initially, a system of coupled differential equations, including energy, mass, and momentum conservation equations is considered, and an analytical method called AGM is employed to solve the problem. The method is straightforward and comprehensible and can be used to solve various nonlinear partial differential equations (PDEs). Results indicate the accuracy of the applied method for solving nonlinear partial differential equations.

Keywords: AGM, analytical solution, porous media, thermo-hydro-mechanical, unsaturated soils

Procedia PDF Downloads 181
1707 Reliability-Based Design of an Earth Slope Taking into Account Unsaturated Soil Properties

Authors: A. T. Siacara, A. T. Beck, M. M. Futai

Abstract:

This paper shows how accurately and efficiently reliability analyses of geotechnical installations can be performed by directly coupling geotechnical software with a reliability solver. An earth slope is used as the study object. The limit equilibrium method of Morgenstern-Price is used to calculate factors of safety and find the critical slip surface. The deterministic software package Seep/W and Slope/W is coupled with the StRAnD reliability software. Reliability indexes of critical probabilistic surfaces are evaluated by the first-order reliability methods (FORM). By means of sensitivity analysis, the effective cohesion (c') is found to be the most relevant uncertain geotechnical parameter for slope equilibrium. The slope was tested using different geometries, taking into account unsaturated soil properties. Finally, a critical slip surface, identified in terms of minimum factor of safety, is shown here not to be the critical surface in terms of reliability index.

Keywords: slope, unsaturated, reliability, safety, seepage

Procedia PDF Downloads 102
1706 Critical Heights of Sloped Unsupported Trenches in Unsaturated Sand

Authors: Won Taek Oh, Adin Richard

Abstract:

Workers are often required to enter unsupported trenches during the construction process, which may present serious risks. Trench failures can result in death or damage to adjacent properties, therefore trenches should be excavated with extreme precaution. Excavation work is often done in unsaturated soils, where the critical height (i.e. maximum depth that can be excavated without failure) of unsupported trenches can be more reliably estimated by considering the influence of matric suction. In this study, coupled stress/pore-water pressure analyses are conducted to investigate the critical height of sloped unsupported trenches considering the influence of pore-water pressure redistribution caused by excavating. Four different wall slopes (1.5V:1H, 2V:1H, 3V:1H, and 90°) and a vertical trench with the top 0.3 m sloped 1:1 were considered in the analyses with multiple depths of the ground water table in a sand. For comparison, the critical heights were also estimated using the limit equilibrium method for the same excavation scenarios used in the coupled analyses.

Keywords: critical height, matric suction, unsaturated soil, unsupported trench

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1705 Development of In Situ Permeability Test Using Constant Discharge Method for Sandy Soils

Authors: A. Rifa’i, Y. Takeshita, M. Komatsu

Abstract:

The post-rain puddles problem that occurs in the first yard of Prambanan Temple are often disturbing visitor activity. A poodle layer and a drainage system has ever built to avoid such a problem, but puddles still didn’t stop appearing after rain. Permeability parameter needs to be determined by using more simple procedure to find exact method of solution. The instrument modelling were proposed according to the development of field permeability testing instrument. This experiment used proposed Constant Discharge method. Constant Discharge method used a tube poured with constant water flow. The procedure were carried out from unsaturated until saturated soil condition. Volumetric water content (θ) were being monitored by soil moisture measurement device. The results were relationship between k and θ which drawn by numerical approach Van Genutchen model. Parameters θr optimum value obtained from the test was at very dry soil. Coefficient of permeability with a density of 19.8 kN/m3 for unsaturated conditions was in range of 3 x 10-6 cm/sec (Sr= 68 %) until 9.98 x 10-4 cm/sec (Sr= 82 %). The equipment and testing procedure developed in this research was quite effective, simple and easy to be implemented on determining field soil permeability coefficient value of sandy soil. Using constant discharge method in proposed permeability test, value of permeability coefficient under unsaturated condition can be obtained without establish soil water characteristic curve.

Keywords: constant discharge method, in situ permeability test, sandy soil, unsaturated conditions

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1704 Numerical Assessment on the Unsaturated Behavior of Silty Sand

Authors: Seyed Abolhassan Naeini, Ali Namaei

Abstract:

This investigation presents the behavior of the unsaturated silty sand by calculating the shear resistance of the specimens by numerical method. In order to investigate this behavior, a series of triaxial tests have been simulated in constant water condition. The finite difference software FLAC3D has been carried out for analyzing the shear resistance and the results are compared with findings from a previous laboratory tests. Constant water tests correspond to a field condition where the rate of the loading is much quicker than the rate at which the pore water is able to drain out of the soil. Tests were simulated on two groups of the silty sands. The obtained results show that the FLAC software may be able to simulate the behavior of specimens with the low suction value magnitude. As the initial suction increased, the differences between numerical and experimental results increased, especially in loose sand. Since some assumptions were used for input parameters, a conclusive result needs more investigations.

Keywords: finite difference, shear resistance, unsaturated silty sand, constant water test

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1703 Investigating Optical Properties of Unsaturated Polyurethane Matrix and Its Glass Fiber Composite Under Extreme Temperatures

Authors: Saad Ahmed, Sanjeev Khannaa

Abstract:

Glass fiber reinforced polymers are widely used in structural systems as load-bearing elements at both high and low temperatures. This investigation presents the evaluation of glass fiber reinforced unsaturated polyurethane under harsh conditions of changing temperature and moisture content. This study Explores how these parameters affect the optical properties of the polymer matrix and the composite. Using the hand layup method, the polyurethane resin was modified by E-glass fibers (15 vol. %) to manufacture fiber-reinforced composite. This work includes the preparation of glass-like polyurethane resin sheets and estimates all light transmittance properties at high and very low temperatures and wet conditions. All-optical properties were retested to evaluate the level of improvement or failure. The results found that when comprising reinforced composite fiber to the unreinforced specimens, the reinforced composite shows a fair optical property at high temperatures and good performance at low temperatures.

Keywords: unsaturated polyurethane, extreme temperatures, light transmittance, haze number

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1702 Effects of Daily Temperature Changes on Transient Heat and Moisture Transport in Unsaturated Soils

Authors: Davood Yazdani Cherati, Ali Pak, Mehrdad Jafarzadeh

Abstract:

This research contains the formulation of a two-dimensional analytical solution to transient heat, and moisture flow in a semi-infinite unsaturated soil environment under the influence of daily temperature changes. For this purpose, coupled energy conservation and mass fluid continuity equations governing hydrothermal behavior of unsaturated soil media are presented in terms of temperature and volumetric moisture content. In consideration of the soil environment as an infinite half-space and by linearization of the governing equations, Laplace–Fourier transformation is conducted to convert differential equations with partial derivatives (PDEs) to ordinary differential equations (ODEs). The obtained ODEs are solved, and the inverse transformations are calculated to determine the solution to the system of equations. Results indicate that heat variation induces moisture transport in both horizontal and vertical directions.

Keywords: analytical solution, heat conduction, hydrothermal analysis, laplace–fourier transformation, two-dimensional

Procedia PDF Downloads 173
1701 Spectroscopy Study of Jatropha curcas Seed Oil for Pharmaceutical Applications

Authors: Bashar Mudhaffar Abdullah, Hasniza Zaman Huri, Nany Hairunisa

Abstract:

This study was carried out to determine the thermal properties and spectroscopy study of Malaysian Jatropha curcas seed oil. The J. curcas seed oil physicochemical properties such as free fatty acid (FFA %), acid value, saponification value, iodine value, unsaponifiable matter, and viscosity (cp) gave values of 1.89±0.10%, 3.76±0.07, 203.36±0.36 mg/g, 4.90±0.25, 1.76±0.03%, and 32, respectively. Gas chromatography (GC) was used to determine the fatty acids (FAs) composition. J. curcas seed oil is consisting of saturated FAs (19.55%) such as palmitic (13.19%), palmitoleic (0.40%), and stearic (6.36%) acids and unsaturated FAs (80.42%) such as oleic (43.32%) and linoleic (36.70%) acids. The thermal properties using differential scanning calorimetry (DSC) showed that crystallized TAG was observed at -6.79°C. The melting curves displayed three major exothermic regions of J. curcas seed oil, monounsaturated (lower-temperature peak) at -31.69°C, di-unsaturated (medium temperature peak) at -20.23°C and tri-unsaturated (higher temperature peak) at -12.72°C. The results of this study showed that the J. curcas seed oil is a plausible source of polyunsaturated fatty acid (PUFA) to be developed in the future for pharmaceutical applications.

Keywords: Jatropha curcas seed oil, thermal properties, crystallization, melting, spectroscopy

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1700 Crosslinking of Unsaturated Elastomers in Presence of Aromatic Chlorine-Containing Compounds

Authors: Shiraz M. Mammadov, Elvin M. Aliyev, Adil A. Garibov

Abstract:

The role of the disulfochloride benzene in unsaturated rubbers (SKIN, SKN-26) which is in the systems of SKIN+disulfochloride benzene and SKN-26+disulfochloride benzene was studied by the radiation exposure. By the usage of physical, chemical and spectral methods the changes in the molecular structure of the rubber were shown after irradiation by y-rays at 300 kGy. The outputs and the emergence of the crosslinking in the elastomers for each system depending on absorbed dose were defined. It is suggested that the mechanism of radiation occurs by the heterogeneous transformation of elastomers in the presence of disulfochloride benzene.

Keywords: acrylonitrile-butadiene rubber, crosslinking, polyfunctional monomers, radiation, sensitizier, vulcanization

Procedia PDF Downloads 405
1699 Static Study of Piezoelectric Bimorph Beams with Delamination Zone

Authors: Zemirline Adel, Ouali Mohammed, Mahieddine Ali

Abstract:

The FOSDT (First Order Shear Deformation Theory) is taking into consideration to study the static behavior of a bimorph beam, with a delamination zone between the upper and the lower layer. The effect of limit conditions and lengths of the delamination zone are presented in this paper, with a PVDF piezoelectric material application. A FEM “Finite Element Method” is used to discretize the beam. In the axial displacement, a displacement field appears in the debonded zone with inverse effect between the upper and the lower layer was observed.

Keywords: static, piezoelectricity, beam, delamination

Procedia PDF Downloads 378