scholarly journals Stress-Strain and Strength Behavior of Undrained Organic Soil in Kupondol, Kathmandu

1970 ◽  
Vol 8 (1-2) ◽  
pp. 113-118
Author(s):  
Padma Bahadur Khadka
Keyword(s):  
Residential Buildings ◽  
Research Work ◽  
Organic Soil ◽  
Engineering Properties ◽  
High Water Content ◽  
Organic Layer ◽  
Foundation Engineering ◽  
Foundation Design ◽  
Stress Strain ◽  
Geotechnical Investigations

The Kathmandu valley is mostly composed of an organic layer locally known as Kalimati, meaning black soil in Nepali. In spite of the unsuitability of organic soil as foundation subsoil, due to its high compressibility and low strength, many civil engineering structures (i.e. residential buildings and high-rise commercial buildings) are being built at an alarming rate. Even more alarming is the fact that no systematic and comprehensive studies have ever been conducted on the geotechnical properties of this highly problematic soil deposit. Geotechnical investigations that have been performed for construction projects, including those structures whose foundation lies on Kalimati soil, typically contain data on general properties of the soil and only to some extend the consolidation and the shear parameter obtained from unconfined compression tests and direct shear tests. As the local name indicates, these soils are black in color, having a high water content and high liquid limit and they are hard when dry but soft when wet. The organic soil is found at different depths and different thicknesses. Sometimes it exists too deep to have a significant effect on the foundation. In many areas it exists at a shallow depth with significant thickness, thus having considerable effect on the foundation of the structure above it. While existing data provides useful information for the design of foundations, almost no data exists on the undrained behavior of the soil, which foundation design on this type of soil should be based on. There is a serious need for research work related to behavior of undrained organic soil deposits in the Kathmandu. Specifically pore pressure, shear strength and stress-strain characteristics, especially under triaxial compression.Key Words: Organic deposit; Foundation; Engineering properties; Kalimati; Geotechnical investigationDOI: http://dx.doi.org/10.3126/jie.v8i1-2.5101Journal of the Institute of Engineering Vol. 8, No. 1&2, 2010/2011Page: 113-118Uploaded Date: 20 July, 2011

scholarly journals Particle Crushing Effect on The Geotechnical Properties of Soil

2019 ◽  
Vol 9 (3) ◽  
pp. 4131-4135
Author(s):  
T. A. Rind ◽  
H. Karira ◽  
A. A. Jhatial ◽  
S. Sohu ◽  
A. R. Sandhu
Keyword(s):  
Research Work ◽  
Testing Machine ◽  
Particle Breakage ◽  
Engineering Properties ◽  
Soil Conditions ◽  
Soil Behavior ◽  
Foundation Design ◽  
Soil Particles ◽  
Ground Conditions ◽  
The Impact

Foundations are considered as the backbone of a structure. Most of the times, the foundation is laid on the soil. For the foundation design of any structure, we need to know beforehand the soil conditions such as shear strength and permeability. These parameters help us determine the bearing capacity of the soil. The soil conditions are determined by performing various laboratory tests such as shear box test or tri-axial shear test. However, we cannot design the foundation considering these data as the ground conditions will change once the loads are applied to the soil as there are some soil particles with angularity or sharp edges will break. Once they will break, soil conditions will not remain the same as they were before since the gradation will change. This work is carried out in order to know the impact soil breakage brings to the soil (granular soil). For this purpose, actual ground conditions were simulated in the laboratory by applying one-dimensional compression to soil particles for about 45 minutes in a Universal Testing Machine (UTM). Different crushing loads to soil particles were applied and the change in the soil behavior was monitored. It was found that due to particle breakage of soil, the engineering properties of sand altered. This research work aims to analyze the effect of particle breakage only in the case of sand.

scholarly journals Investigation of hydrogeomechanical parameters of loess massifs in conditions of technogenic underflooding and development of technical recommendations for strengthening of bases of foundations

2019 ◽  
Vol 28 (1) ◽  
pp. 173-179 ◽  
Author(s):  
I. O. Sadovenko ◽  
A. M. Puhach ◽  
N. I. Dereviahina
Keyword(s):  
Strain State ◽  
Quantitative Estimation ◽  
Residential Buildings ◽  
Finite Element Approximation ◽  
Element Approximation ◽  
Soil Base ◽  
Stress Strain ◽  
Elastic Mode ◽  
Stress Strain State ◽  
Water Saturated

Based on the analysis of actual data and the results of numerical modeling, dependencies of deformations of the investigated residential complex due to technogenic moistening of a loess massif of soils are investigated. It was established that a dynamics of subsidence of bench marks in time is closely correlated with a moistening mode. In order to form a picture of dynamics of development of moistening phases of the massif and a quantitative estimation of main factors of their formation, a numerical model of the loess massif was built, based on the finite element approximation of the section of built-up area of the residential complex. Stability of a soil massif was estimated by the character of development of plastic deformation zones. Analysis of a stress-strain state of a rock massif indicated that water-saturated soils are partially in a state of plastic flow in a base. The development of shear deformations is most characteristic within a zone of the main moistening, as well as a boundary of its front. Development of rupture disturbances at the edge of the contour of buildings corresponds with the formation of tear cracks. An intensification of subsidence of buildings with simultaneous frontal and subvertical technogenic moistening of loess soils can be noted. Model estimations of a stress-strain state of the pile foundation, considering the uneven subsidence that occurred along the perimeter of residential buildings, show that the elastic mode of their deformation has not been exhausted. Options of redistribution of loads from residential sections onto an additional pile field, regulated base moistening and grouting of soils are considered as engineering measures to prevent further deformation of the residential complex. Stabilization of a soil base by means of high-pressure cementation is the most acceptable in the present conditions. Technological scheme of cementation of the soil base is recommended, as well as measures after the base stabilization, such as monitoring of further deformations of the complex itself and parking structures, and possibilities of constructing auxiliary drainage.

scholarly journals CHARACTERIZING A TROPICAL SOIL VIA SEISMIC IN SITU TESTS

2019 ◽  
Vol 37 (3) ◽  
pp. 263
Author(s):  
Breno Padovezi Rocha ◽  
Heraldo Luiz Giacheti
Keyword(s):  
Shear Modulus ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Soil Profile ◽  
Site Investigation ◽  
Tropical Soil ◽  
Engineering Properties ◽  
Foundation Engineering

ABSTRACT. The shear wave velocity (Vs) is an important geotechnical parameter to be used in dynamic problems (e.g. earthquakes and vibration problems) as well as in static deformation analysis such as excavations and foundation engineering design. There are several in situ seismic tests to determine Vs such as the crosshole and the downhole techniques, as well as hybrid tests (e.g. seismic dilatometer – SDMT). This paper presents crosshole, downhole and SDMT tests carried out in a typical tropical soil profile from Brazil. Advantages and limitations regarding the test procedures and interpretation are briefly presented and differences observed among Vs determined by these techniques are discussed. Shear wave velocities (Vs) estimated from the crosshole, downhole and SDMT tests ranging from 194 to 370 m/s. The shear wave velocity suggests that the experimental site could be divided into two strata, which are in agreement with soil profile description. The maximum shear modulus (G0) calculated from the Vs by theory of elasticity can be used to show the investigated tropical soil is a typical unusual geomaterial. This article also emphasizes that the SDMT is a useful test for site investigation since it allows a great means for profiling geostratigraphy and soil engineering properties during routine site investigation as well as for dynamics problems. Keywords: shear wave velocity, maximum shear modulus, crosshole, downhole, SDMT.RESUMO. A velocidade de onda cisalhante (Vs) é um parâmetro geotécnico empregado em análises dinâmicas (terremotos e problemas de vibração), bem como em análises estáticas (escavações e projeto de fundações). Existem vários ensaios sísmicos de campo para a determinação de Vs, entre eles as técnicas crosshole e downhole, e os ensaios híbridos (por exemplo, dilatômetro sísmico – SDMT). Este artigo apresenta os ensaios crosshole, downhole e SDMT realizados em um perfil típico de solo tropical do Brasil, as vantagens e limitações dos procedimentos de ensaio e de interpretação são brevemente apresentadas, e as diferenças observadas entre os valores de Vs determinados pelas diferentes técnicas são discutidas. Os perfis de Vs determinados pelas diferentes técnicas variaram de 194 a 370 m/s. A velocidade da onda cisalhante sugere que o campo experimental investigado pode ser dividido em dois horizontes, os quais estão de acordo com a descrição do perfil do solo estudado. O módulo de cisalhamento máximo (G0), calculado a partir de Vs pela teoria da elasticidade, pode ser utilizado para demonstrar o comportamento não convencional do solo investigado. Este artigo também enfatiza que o SDMT é um ensaio geotécnico útil para a investigação geotécnica do subsolo, uma vez que permite a definição do perfil estratigráfico e a estimativa de parâmetros estáticos e dinâmicos de um projeto.Palavras-chave: velocidade de onda cisalhante, módulo de cisalhamento máximo, crosshole, downhole, SDMT.

Improving Safety when Extracting Water-soluble Ores by Optimizing the Parameters of the Backfill Mass

2021 ◽  
pp. 53-59
Author(s):  
M.M. Khayrutdinov ◽  
◽  
Ch.B. Kongar-Syuryun ◽  
A.M. Khayrutdinov ◽  
Yu.S. Tyulyaeva ◽  
...  
Keyword(s):  
Strain State ◽  
Raw Materials ◽  
Research Work ◽  
Integrated Approach ◽  
Water Soluble ◽  
Mining Operations ◽  
Stress Strain ◽  
Mining System ◽  
Stress Strain State ◽  
Geological Conditions

The results of the scientific and research work devoted to modeling the stress-strain state of the mining system of an underground mine using the finite element method in the FLAC3D software are presented in the article. The possibility of using room-and-pillar mining with backfill with the abandonment of chain pillars is justified. The results are presented concerning the research results of the quantitative assessment of the mass using the von Mises equation and Norton' power law of creep to estimate the contour stress. It becomes possible to determine the sequence of mining of the deposit area and the stage-by-stage filling of the stopes at the stage of mining design due to the high accuracy of modeling the stress-strain state of the mass near mining operations using FLAC3D software. The proposed approach is possible when evaluating the geotechnical state of the rock mass when using the mining systems with various methods of support of the mined-out area: natural; artificial; with the collapse of ores and enclosing rocks, as well as when calculating the combined method of deposit development. A differentiated approach to assessing the state of the mass is possible considering difficult mining and geological conditions, conditions of increased rock pressure, abundant water influx, increased fracturing of rocks by introducing additional conditions into the model depending on its geotechnical state. Variant of the comprehensive exploitation of mineral resources was proposed considering the total value of natural and man-made geo-resources of the area being mined. The possibility of rational use of the mined-out space with the use of various positive qualities of geo-resources at their manmade transformation is also considered. An assessment of the mineral and raw materials potential of the mined area is given with a proposal for the prospects of increasing the integrated approach of excavation, increasing the life of the mining enterprise and the complexity of developing this area.

Estimation of construction and demolition waste volume generation in new residential buildings in Spain

2011 ◽  
Vol 30 (2) ◽  
pp. 137-146 ◽  
Author(s):  
Paola Villoria Sáez ◽  
Mercedes del Río Merino ◽  
César Porras-Amores
Keyword(s):  
Residential Buildings ◽  
Research Work ◽  
Construction And Demolition Waste ◽  
Construction Process ◽  
Demolition Waste ◽  
Management Planning ◽  
Housing Projects ◽  
Single Indicator

The management planning of construction and demolition (C&D) waste uses a single indicator which does not provide enough detailed information. Therefore the determination and implementation of other innovative and precise indicators should be determined. The aim of this research work is to improve existing C&D waste quantification tools in the construction of new residential buildings in Spain. For this purpose, several housing projects were studied to determine an estimation of C&D waste generated during their construction process. This paper determines the values of three indicators to estimate the generation of C&D waste in new residential buildings in Spain, itemizing types of waste and construction stages. The inclusion of two more accurate indicators, in addition to the global one commonly in use, provides a significant improvement in C&D waste quantification tools and management planning.

An analysis of stress–strain behaviour and wetting effects on quarried rock shells

2005 ◽  
Vol 42 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Ignacio Escuder ◽  
Joaquin Andreu ◽  
Manuel Rechea
Keyword(s):  
Cross Sections ◽  
Research Work ◽  
Road Construction ◽  
Stress Strain ◽  
Simulation Procedure ◽  
Earth Core ◽  
Strain Behaviour ◽  
Points Of View ◽  
Nonlinear Elastic ◽  
Strain Model

The analysis of stress–strain behaviour and the effects of submergence on quarried rock shells, used mainly in dams but also in road construction, is of major importance from both economic and safety points of view. The research work presented here starts with an in-depth review of the nonlinear elastic procedure widely used in rockfill analyses since 1970, its later application to simulate wetting effects, and the latest published modifications to the so-called hyperbolic stress–strain model. An update of the existing wetting simulation procedure has been formulated, calculation routines to analyze constructional behaviour and wetting effects on rockfills have been implemented, and the methodology developed has been applied to a structure 100 m high. Calculation routines have been written to run in FLAC, a finite difference based code that incorporates a programming language. The analyzed structure is part of a road rockfill located at the Contreras Reservoir in Spain and consists specifically of two shell-shaped cross sections subjected to the influence of submergence. The results are expected to be useful in estimating collapse settlements in the upstream shells of earth-core dams.Key words: elasticity, stress–strain, rockfills, behaviour, numerical, dams.

scholarly journals Engineering Characterization of Subgrade Soils of Jimma Town, Ethiopia, for Roadway Design

Geosciences ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 94
Author(s):  
Alemineh Sorsa ◽  
Sanjaya Senadheera ◽  
Yoseph Birru
Keyword(s):  
Engineering Properties ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
High Plasticity ◽  
Soil Characterization ◽  
Engineering Structures ◽  
Undisturbed Soil ◽  
Subgrade Soil ◽  
Geotechnical Investigations ◽  
Jimma Town

Soils are naturally occurring materials that carry loads of civil engineering structures including roads and buildings. However, not all natural soils are suitable for such uses due to limited strength and instability under varying environmental conditions. A lack of adequate geotechnical investigations and soil characterization can result in the over-design of foundations, unexpected excavations to remove unsuitable soils, cost overruns, construction delays; and, contract disputes. In this research, an experimental plan was executed to determine the engineering properties of subgrade soil in Jimma Town in southwestern Ethiopia by using both disturbed and undisturbed soil samples. The plan included tests to determine the moisture content, specific gravity, grain-size analysis, Atterberg limits, compaction-density relationship, California Bearing Ratio (CBR), unconfined compression strength, and triaxial shear strength. X-ray diffraction (XRD) analysis was also conducted to determine the chemical composition of the soil. The soil characterization indicated that soft clay is the predominant subgrade soil type and that it has a very low load-bearing capacity, high plasticity, low strength and, high compressibility, which makes the soil unsuitable to serve as a highway subgrade without the help of soil improvement techniques.

Impact Behaviour of Metallic Fibre Reinforced Concrete and Mortar

1990 ◽  
Vol 211 ◽  
Author(s):  
P. Hamelin ◽  
M. Razani
Keyword(s):  
Reinforced Concrete ◽  
Strain Rate ◽  
Damage Model ◽  
Research Work ◽  
Fibre Reinforced Concrete ◽  
Stress Strain ◽  
Impact Behaviour ◽  
Experimental Apparatus ◽  
The Impact ◽  
Behaviour Law

AbstractThis research work concerns the impact behaviour of metallic fibre reinforced concrete. After a description of the experimental apparatus used, an air compressed gun, we present the main results in terms of stress–strain diagrams as a function of the strain rate. Then, we establish equations of a specific damage model which take account of the different phases of the behaviour law.

Analysis on Rheological Properties of Peat Soil in Kunming Area

2012 ◽  
Vol 204-208 ◽  
pp. 722-726
Author(s):  
Yi Peng Guo ◽  
Xiao Nan Wang ◽  
Zheng Fa Lai ◽  
Jun Qing Lv
Keyword(s):  
Rheological Properties ◽  
Stress Level ◽  
Peat Soil ◽  
Strain Curve ◽  
High Water ◽  
Engineering Properties ◽  
Dianchi Lake ◽  
High Water Content ◽  
Peat Soils ◽  
Loading And Unloading

Kunming area is adjacent to Dianchi Lake. Peat soil with high water content and high compressibility is widely distributed, rheological properties is one of the most important engineering properties of peat soil. However, compared with the peat soils in the other areas, the peat soil in Kunming area has different properties. This paper studied rheological properties of peat soil in Kunming area by using the creep test of loading and unloading, on the basis of the strain-time curves, parting linear visco-elasticity, linear visco-plasticity and nonlinear visco-plasticity from the total deformation. Research shows that: ①The deformation is mostly composed of unrecoverable deformation and there is instantaneous elastic strain, instantaneous plastic strain in total strain; ②In low stress level,the soil is rendered as visco-elasticity. However, when the stress level is high, the performance of soil is visco-plasticity; ③By stress-strain curve clusters, yield stress of peat soil is approximate to 3.6 kPa in Kunming; ④Along with the time, modulus of linear visco-elasticity tended to be stable.

scholarly journals Ultrasoft Ground Treatment of Vacuum Preloading Combined with Calcium-Based Flocculants

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Jin-Kai Yan ◽  
Feng Ji ◽  
Xia Bian ◽  
Gui-Zhong Xu ◽  
Lei Liu ◽  
...  
Keyword(s):  
Transmission Rate ◽  
Threshold Value ◽  
High Water ◽  
Soil Strength ◽  
Frame Structure ◽  
Vacuum Pressure ◽  
Engineering Properties ◽  
High Water Content ◽  
Vacuum Preloading ◽  
Prefabricated Vertical Drains

Vacuum preloading is one of the popular methods improving the engineering properties of slurry ground with high water content. Commonly, the efficiency of vacuum preloading gradually decreased due to the clogging of prefabricated vertical drains (PVDs) and the low-vacuum transmission rate inside slurry. Thus, the calcium-based flocculants were used to accelerate the dewater capacity and enhance the soil strength during vacuum preloading. This paper performed a series of model tests to investigate the effect of calcium-based flocculants on the efficiency of vacuum preloading. It is found that the vacuum transmission rate was significantly improved by flocculants in comparison with raw slurry. Accordingly, the after-treatment undrained shear strength increased with the vacuum pressure, while the after-treatment water showed a decrease trend. This suggests that the increase of vacuum transmission rate inside the slurry due to the calcium-based flocculants was the main reason for the improvement of efficiency of vacuum preloading. In addition, there existed an optimal flocculants amount, where the vacuum pressure increased with flocculants’ amount up to this threshold value, followed by a decrease in vacuum pressure. This means that, at lower flocculants amount, the increase in soil flocs due to flocculation effect tended to refine the net-frame structure and water flow path, leading to an increase in the efficiency of vacuum preloading. When exceeding the optimal amount, overdosage of flocculants resulted in the clogging of PVDs due to large cemented soil particles, reducing the vacuum transmission rate inside the slurry. Hence, the after-treatment soil strength decreased with flocculants’ amount when it is higher than the optimal value.

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