The Tehri dam is the highest dam in India. The height of dam is 260 m. It is situated on the Himalayan region which is in earthquake prone region. A Sengupta in 2006 found that the predicted deformation due to an M=7.0 earthquake are not large enough to compromise the safety of the dam. However the deformation predicted by Seed and Makdisi’s method, and Bureau’s method for an M=8.5 earthquake are large enough to compromise the safety of dam. The Seed and Makdisi’s procedure predicted the maximum deformations, while the minimum deformations are computed by Jansen’s method. In the present work, the stability analysis four type of analysis such as structural stability analysis, Centre of slip circle by genetic algorithm, stability of dam under sudden draw down condition and dynamic analysis are considered Structural stability analysis have done by Fellenius method and radial slice method. In Fellenius method three number of slip circles are taken which cuts the slope at two third distances from top of slope. By finding the resisting moment and driving moment the factor of safety is found that for first slip circle, second slip circle and third slip circle are 1.997, 2.103 and 2.045 respectively. In the radial slice method the failure wages are divided into number of slice radially by joining the line from the center of slip circle to the arch. The factor of safety is found as 1.15. The coordinate of centre of slip circle has found by genetic algorithm. In order to validate the genetic algorithm method, the input data has been imported from the results of graphical method. The centre coordinate of slip circle is obtained as (210,485) which was found to be very close the value of centre of slip circle by graphical method. Numerical analysis has been made by using commercially available software PLAXIS under sudden draw down condition. The deformation in X-direction was 16.99 m. Dynamic analysis has been used by PLAXIS software and the total deformation is obtained as 0.4150 m.
This paper deals with the various techniques used to segregate municipal solid waste based on its size and types. We study various research works and ongoing industry practices and finally summarize a general process that is being used to segregate municipal solid waste. This paper also addresses the major problem related to segregating waste as wet and dry and the existing technologies that are being used in industries to segregate municipal solid waste. The methods used to detect moisture in waste materials, are also discussed along with their pros and cons. For this study, we have considered the practices used to segregate waste in India and how they can be improved by implementing the technologies used in other countries in the existing Indian waste management scenario.
Over growing demand of water has led scientific community to plan augmentation of ground water by various methods. The objectives achieved in present study are to arrest run-off and silt flow, to facilitate infiltration of water. The study area considered is a small Micro Watershed from South Solapur District which is Drought prone zone. The study was an attempt to delineate the possible recharge zone for groundwater and also to identify the suitable sites for artificial recharge structures. The remote sensing, geographic information system and electrical resistivity (VES) has played important role in investigation for identifying the probable sites for artificial recharge structures.Subsurface resistivity sounding studies have revealed to know the subsurface lithological distribution and thickness of different layers and this has been correlated with local geological setup to suggest the artificial recharge structures.
Notwithstanding the broad hypothetical work about hydraulic fracturing technique for estimation of stresses in rock mass, the experimental work has so far been restricted, particularly on account of its legitimacy in fractured rocks. Much work has been completed about the induced fractures created by hydraulic fracturing tests, however not on the impact of previously existing fractures and joints and their impact. When a fracture has been originated at the borehole wall, the fluid infiltrates the splitting of the rocks, and the pressure is applied to the walls of the fracture. In this way, the least downhole infusion pressure expected to hold open and expand a crack is somewhat higher than the normal to the plane of the fracture. To overcome the above issue, a sequence of hydraulic fracturing tests was performed on fractured rock masses inside the tunnel of one of the hydroelectric projects. The applied pressures in these tests were stretched out past the standard reaches (6 to 8 l/min), coming to up to 20 MPa with a flow capacity of up to 16 l/min. It was seen that by expanding or diminishing the pumping pressure for each cycle, the fracture opening pressure declined consequently after specific augmentation. It is deciphered that, since the entire fractured rock mass is exposed to the flow of water; these events are because of the opening of fractures at various spatial positions. When high pressure gradients exist, especially when the permeability increases abruptly as the effective pressure approaches zero, a sharp pressure front develops in the region, moving outward from the borehole. If the permeability upsurges with increasing pore pressure, a steep pressure gradient will tend to grow. After shutoff the pump, rapid shut-in pressure is obtained to get the normal stress across the fracture and to calculate the minimum principal stress magnitude and direction. This is the state-of-the-art technique established by the authors for determination of the stresses in fractured ground environments. KEYWORDS: Hydraulic fracturing; fractured rocks; high flow rate; normal stress.
In the present study, a sinusoidal shear and normal deformation theory taking into account effects of transverse shear as well as transverse normal is used to develop the analytical solution for the bidirectional bending analysis of isotropic, transversely isotropic, laminated composite and sandwich rectangular plates. Governing equations and boundary conditions of the theory are obtained using the principle of virtual work. The Navier solution for simply supported laminated composite plates have to develop. Results obtained for displacements and stresses of simply supported rectangular plates have to compare with those of other refined theories and exact elasticity solution wherever applicable. The Navier-type exact solutions for static bending analysis are have to for sinusoidally and uniformly distributed loads. The accuracy of the present theory is ascertained by comparing it with various available results in the literature. Keywords: Trigonometric shear deformation theory, Transverse inplane stress, Transverse displacement, Trigonometric function
Soil liquefaction often occurs in saturated or partially saturated silty or sandy soil when an earthquake generates dynamic cyclic stress in the soil mass, reducing shear strength and stiffness. This study aims to assess the seismic soil liquefaction hazard potential for Sylhet City using shear wave velocity profiles of 49 boreholes. Factor of Safety (FOS) was evaluated taking into account shear wave velocity and maximum intensity of surface acceleration corresponding to Srimangal earthquake of magnitude 7.6. FOS maps with colour index based on maximum and average amplification were generated. The central-western part and central-eastern parts of the city show a minimum FOS of 0.31-0.8. Spatial distribution of clustered LPI values using GIS was analyzed considering a threshold value LPI of 5 for the liquefaction to be initiated for Sylhet City. The developed contour maps also depict the site-specific liquefaction intensity based on the LPI values of each borehole. The liquefaction potentiality of the city area varies from very low to low, low to high, and very high. Keywords: Liquefaction potential index, Shear wave velocity, Factor of safety, Cyclic stress ratio, Amplification factor.
A numerical parametric study using the finite element program of OPTUM G2 was performed on single, double, and triple anchored sheet piles systems retaining sandy soil. The present paper evaluates the variation of maximum shear force distribution, bending moment distribution, and displacement of soil and sheet pile wall concerning different depths of excavation, embedded depth of sheet pile wall, and position of anchor in retention system. Flexible plate elements, Mohr-coulomb sand is considered for modeling of sheet pile wall and soil respectively. The maximum displacement of soil and sheet pile wall for various models are calculated by considering 6-node gauss elements and by using elastoplastic analysis. This method governs the stability of structures in terms of settlement criteria. This analysis also shows the possible potential failure of shear dissipation at different conditions in soil structure. Keywords: Finite element method, Sheet pile, Anchor, Elastoplastic analysis, Bending moment, Shear force, Optum G2.
Failure of the soil slopes by dynamic excitation is one of the most vital geotechnical earthquake hazards which may lead to serious destruction to the bridge abutments, dams, embankment, and structures resting on the slope. Moreover, due to deficient space available for the construction of slopes in urban areas, high and steep slope is constructed by geotextile reinforcement slopes. In this study, numerical modelling is made to study the behaviour of soil slope reinforced by geotextile under earthquake loading using the finite element method available in, optumG2. The value of the factor of safety (FOS) for unreinforced soil slope is calculated using the strength reduction method (SRM) at slope angle (β = 60°) and the height of the slope is 10 m. In the unreinforced slope, a critical failure surface was obtained due to which slope is reinforced with geotextile under static and earthquake loading. Furthermore, a parametric analysis is carried out to evaluate the effect on different lengths of geotextile and different vertical spacing for the stability of reinforced slope with horizontal ground acceleration coefficient (0.1-0.4). From the outcomes of the present study, it is noted that a stable slope can be achieved with an optimized configuration of the reinforcement under seismic loading, also a steeper slope can be achieved using reinforcement compared to that of an unreinforced slope.
Strength is important factor for stability of structure tо meet sрeсified engineering requirements оf sоil аnd to mаke it mоre stаble. For this purpose, certain engineering рrорerties are required tо be altered/changed. Based on the literature available, In the present study, аn exрerimentаl investigation is undertаken tо investigаte the effeсt оf addition of geofibers in different proportions (0.0-2.0% by weight) with two fiber lengths of 6 mm and 12 mm оn two different soils i.e. SP and CL soils. The two soil samples were collected from the nearby area of Sultanpur. The original soil samples and the soils added with geofibers are evaluated for engineering and strength properties i.e. Specific gravity, particle size distribution, Atterberg’s limit, Optimum moisture content, Maximum dry density and California bearing ratio (CBR value), using standard test procedures, in Geotechnical laboratory of department. The experimental results thus obtained were further analyzed. The analysis of experimental data shows that addition of geofibers in both the soils helps to increase the strength in terms of the CBR value. The study shows that for both soils the optimum CBR value comes at 1.5% with addition of geofibers for 12 mm fiber length. The percentage increase in CBR value of SP soil is 133% while for CL soil this increase in CBR value is 147%, as compared to the original soils CBR values. Keyword. California Bearing Ratio, Stabilization, Geofibers, Compaction, Soil
This paper establish the beginning of a research process regarding the behavior of soils stabilized with lime. Generally, the geotechnical practice of soils stabilized with lime requires a first step conducted in the laboratory, to attest the features of “natural soils” in order to improve their behavior in term of geotechnical performance and, a second step, carried out onsite with experimental test fields, in order to verify the benefit obtained by the use of lime treatments. The topic of this research focuses on the first step above described. In order to provide geotechnical laboratory tests useful to our purpose, A-4 soils (according to HRB classification) and CL-ML (according to USCS soils classification) were tested. These soils show a large distribution in the Piedmont Po Plain (NW Italy): they outcrop in correspondence to terraced alluvial fans linked to alpine watercourses and are generally applied for stabilization with lime for foundation structures and pavements. Additionally, these soils are mainly inorganic with a marked tendency towards sandy silt soils with the presence of gravel. The presence of gravel results on a greater strain hardening in the behavior of shear strength of soils. Finally, in support of geotechnicians, who have to draw up specifications, a systematized laboratory methodology to follow for A-4 soils stabilization with lime is here reported and a detailed analyses of mechanical behavior obtained on “soil-lime-water mixtures” is described.
In the geotechnical practice, the stabilization of soil using cement is a necessary procedure when soils do not meet the geotechnical requirements i.e. they show low bearing capacity so it’s necessary to improve their engineering properties generally adding lime or cement, or moisture of lime and cement. The aim of this research focuses on the description of a geotechnical laboratory tests plan for A-4 Group Soils according to AASTHO Soils Classification, generally consisting of gravel, sand, and silt that will be treated with cement in order to find both the minimum cement content required to harden this material and the optimum moisture content. This is research been developed in two phases: a) the identification and characterization of physical-mechanical properties of natural soil; b) the study of some experimental cement-soil moistures by laboratory tests in order to find the optimum moisture content of soil, water, and cement. This research shows that the adding of 3% of Portland cement in the soil can furnish a suitable combined stabilization process of these soils. Finally, in support of geotechnical engineering, a quick geotechnical laboratory plan for stabilization with cement and a detailed analyses of mechanical behavior obtained on soil-cement moisture has been reported.
Soil stabilization is a ground improvement technique through which soil is made strong enough to bear the structures load. The swell-shrink properties of expansive soils can be reduced and made useful for construction purposes using various stabilizing materials like cement, lime, fly ash, chemicals, etc. Cement stabilization causes environmental pollution. Microbial-induced carbonate precipitation and enzymatic-induced carbonate precipitation methods can be considered as innovative methods in place of cement soil stabilization. If the cement, lime, fly ash and various chemicals are used in a suitable proportion, the geotechnical properties can be increased during stabilization of soils. The paper also focusses about the expansive and collapsible soils. Keywords: Soil stabilization, expansive soil, collapsible soil, cement, lime, fly ash, chemicals
This paper is part of a research project carried out between Geotechnical Office of Dr. Barbero & collaborators and Weg Ingenieria, from Italy and Argentina, respectively. Given the multiple applications of soils improvement with lime, in this research we proceed to develop correlations on the bases of results obtained by geotechnical tests, according to international standards, realized in A-4 soils at different contents of lime. The goal is to have an order of magnitude and predictability of the behavior of soils stabilized with lime. In this research, we report on the results of two sets of samples improved with lime and tested with unconfined compressive resistence to analyse their strenght. These soils were collected by extraction in a test pit for road works, in the city of Palmira, Department of San Martin, Mendoza, in the Cuyo area, Argentina. Finally, lime stabilization not only promotes high increases in the strength of soils, but also results in a change in the behavior of the soil.
Earth pressure theories occupy a paramount position in the field of geotechnical engineering. The knowledge of active earth pressure under static condition is essential in designing a retaining wall as the damage to such retaining structures may lead to disastrous failure. A retaining wall helps in maintaining the ground surface at different elevations on either side of it. Without such a structure, the soil at higher elevation would tend to move down till it acquires its natural, stable configuration. Laboratory model tests in geotechnical engineering are being performed in small steel test tanks to examine the lateral earth pressure on retaining walls. In present study laboratory model of retaining wall is cantilever type, having model tank of MS (1810 x 1210 mm) in plan and 1000 mm height. The MS plate (1210 x 1000 x 5 mm) acts as a retaining wall. Present work consists of evaluation of active earth pressure by conducting 18 tests on model with different frictional surfaces namely jute, geotextile, thick plastic sheet, cement bag and uniform surcharge of 2.0 kN/m2. All the tests are conducted on dry, cohesionless backfill. Test results show that, when frictional surfaces are attached on the side walls and retaining wall, the deflection of the retaining wall reduces and hence active earth pressure is also reduced. Earth pressure slightly reduces in case of frictional surfaces on side wall as well as on retaining wall as compared to that with frictional surface only on retaining wall. Further it is observed that the reduction of the active earth pressure depends on to the wall friction angle () of frictional surface. Increase in wall friction angle () of surface results in decrease in deflection and thereby corresponding decrease in active earth pressure. Earth pressure obtained in the present work agrees well with Culmann’s graphical method whereas earth pressure by coulomb method is slightly higher than that obtained experimentally.
Expansive soils have been a source of risk to human beings as they causes huge economic loss including damage to buildings, roads and other civil infrastructures because of their low compressive strength and excessive settlement characteristics. One of the available options is to replace such soils before starting any civil engineering construction but looking to huge costs involved in replacement; it is generally not practiced nowadays. Another viable alternative is to improve the engineering properties of such soils through stabilization. The conventional methods of stabilization make use of cement, lime, fly ash, rice husk ash, sawdust ash and other fibrous materials. Researchers are always finding alternative methods of soil stabilization making use of modern scientific techniques which are cost-effective as well as eco-friendly in nature. The present study focuses on producing biochar from agricultural crop residues and making use of it for stabilizing the expansive soils. India being an agricultural country produces a large volume of crop residues which creates an environmental problem in absence of proper management and disposal system. Indian farmers generally practice stubble burning in their fields which causes emission of greenhouse gases in the atmosphere and at the same time damage to the soil biota. A simple indigenous method of producing biochar has been developed wherein the crop residues are converted into biochar which is further applied to expansive soils as a stabilizing agent to improve the physical, chemical and engineering properties. In India, not much work has been carried out hitherto on biochar application to soils. The process of making biochar and the effects of utilizing biochar on the properties of expansive soil have been presented in this paper, which will prove useful for the Indian context where large quantities of agricultural wastes are produced that create environmental air pollution when burnt openly in fields.
Soil Reinforcement is the widely accepted technique to improve the bearing capacity of challenging sites. There are various natural as well as synthetic material available as reinforcement for soil. Nowadays geosynthetic reinforced granular fill material is widely used in soft sub grade soil. This manuscript deals with the experimental studies carried out to explore the possibility of using naturally available bamboo as a geogrid to increase the bearing capacity of the loose granular soil. Bamboo is a natural, ecofriendly and sustainable material with high tensile strength. Small scale load bearing tests were conducted to determine the bearing capacity of the loose fill, with bamboo grid, with rubber noded bamboo grid and the results were compared with that of synthetic geogrids. The analysis of load settlement curves shows that the bamboo grid carries more load when placed at a depth of one fourth of the footing width. The rubber noded bamboo grid carries more load compared to other reinforcement as the rubber node at the intersection of bamboo strips act as shock absorber and there by protect the bamboo grid.
Soil stabilization changes the engineering properties of soil and produces strength and stability. Use of industrial wastes and manufactured materials in soil stabilization can be cost effective and environmental friendly. As there is a growth of habitations surrounding the PSIT campus, therefore, soil samples collected from this area were analyzed for its plasticity index properties. It was found that soils of this area come under low plastic category. Hence, the low plastic category soil was mixed with fly ash and cement having target to use maximum amount of fly ash and minimum amount of cement for soil stabilization. Hence, the proportions: 100% soil; 85% soil, 10% cement and 5% fly ash;82% soil, 8% cement and 10% fly ash; 79% soil, 6% cement and 15% fly ash; 76% soil, 4% cement and 20% fly ash and 73% soil, 2% cement and 25% fly ash were used in this study . All these proportions including soil were analyzed for particle size analysis, shear strength parameters (angle of shearing resistance and cohesion), compaction characteristics (optimum water content and maximum dry density) and California bearing ratio. Coefficient of uniformity and coefficient of curvature were assessed to determine the gradation of particles. Influences of mix proportions were studied on gradation of particles, angle of shearing resistance and cohesion, optimum water content (OMC) and maximum dry density (MDD) and California bearing ratio (CBR). Mix proportions improved the bearing capacity factors, decreased the OMC and increased the CBR values. Keywords: Soil stabilization, cement, fly ash, shear strength parameters, compaction characteristics, California bearing ratio
In geotechnical engineering, clayey soil is considered to be the most complicated deposits in the field of construction purposes. Due to its low bearing strength, shearing strength, high compressibility ,volume change and swell-shrink properties it becomes difficult to construct building and pavement structures which cause a great concern for engineers while designing. Construction of pavements should be done as it is strong and durable for their design life by overcoming causes of deterioration such as maintenance cost, traffic interruptions which creates inconvenience to public. The life of any pavements structures mainly depends on subgrade course provided. Several approaches has recently attempted to encounter the threat present in the soil. Soil stabilization is a immense method for improving soil properties. In recent times, the demand of infrastructures and transportation sectors., soil stabilization has a dominate role, as it is economical and resource-saving method. This paper explains various studies on the current stabilization techniques with natural fibres like coir, jute, bamboo, and palm fibre for improving the engineering properties clayey soil. Keywords : Clayey soil, Natural fibres, CBR and UCS, Optimum moisture content, Maximum dry density, swell and shrink properties.
