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Papers by Akshay Jha
Lecture notes in civil engineering, Dec 11, 2022
Indian Journal of Geosynthetics and Ground Improvement, 2018
Lecture Notes in Civil Engineering
Analysis of earth slopes is one of the oldest geotechnical engineering problems that engineers ha... more Analysis of earth slopes is one of the oldest geotechnical engineering problems that engineers have been dealing with using various techniques. The methods can be classified as limit equilibrium methods (LEM), finite element method (FEM) based on c and φ reduction, finite difference method (FDM), combination of FEM and LEM, limit analysis (LA), etc. Geosynthetic reinforcement of earth slope results in reduction in the land requirement and preservation of natural resources (land and backfill requirements) apart from time and cost. Designing geosynthetic reinforced slope with minimum length of geosynthetics leads to further economy. Jewell et al. [7], Bonparte et al. [3], and Verduin and Holtz [16] present design methods for earth slopes reinforced with geotextiles or/and geogrids using LEM assuming different types of failure surfaces such as circular or/and bilinear wedges. Jewell et al. [7] used limit equilibrium analysis and local stress calculation for design of reinforced slope. Jewell [8] presented revised design charts for steep slopes valid for all polymer reinforcement materials. These revised charts lead to savings of the order of 20-30% in reinforcement quantity. Leshchinsky [9] and Leshchinsky et al. [12] used log spiral failure mechanism to determine the required reinforcement long-term strength. Zhao [17] and Michalowski [14] present kinematic limit analysis solutions for the stability
Lecture Notes in Civil Engineering, 2019
The present paper analyses reinforced steep slope to optimize the length of geosynthetic reinforc... more The present paper analyses reinforced steep slope to optimize the length of geosynthetic reinforcement from the face or near end of the slope with respect to its location, length and combination of multiple layers of reinforcement to obtain the desired minimum factor of safety. In case of walls, the reinforcement needs to extend up to and be tied to wall face due to functional requirement. But in case of slopes, no such requirement exists and hence curtailment of reinforcement from face end is feasible. The effect of providing geosynthetic layer in shifting the critical slip circle has been studied. The interaction between layers of reinforcement has been identified, modelled and quantified. The study facilitates understanding the mechanics of reinforcing slopes which is very different from that of reinforced soil walls.
Slope failures lead to loss of life and damage to property. Slope instability of natural slope de... more Slope failures lead to loss of life and damage to property. Slope instability of natural slope depends on natural and manmade factors such as excessive rainfall, earthquakes, deforestation, unplanned construction activity, etc. Manmade slopes are formed for embankments and cuttings. Steepening of slopes for construction of rail/road embankments or for widening of existing roads is a necessity for development. Use of geosynthetics for steep slope construction considering design and environmental aspects could be a viable alternative to these issues. Methods developed for unreinforced slopes have been extended to analyze geosynthetic reinforced slopes accounting for the presence of reinforcement. Designing geosynthetic reinforced slope with minimum length of geosynthetics leads to economy. This chapter presents review of literature and design methodologies available for reinforced slopes with granular and marginal backfills. Optimization of reinforcement length from face end of the sl...
Geotechnical Engineering Journal of the SEAGS & AGSSEA , 2018
Steepening of slopes for construction of rail/road embankments or for widening for other civil en... more Steepening of slopes for construction of rail/road embankments or for widening for other civil engineering structures is a necessity for development. Use of geosynthetics for steep slope construction or repair of failed slopes considering all aspects of design and environment could be a viable alternative to these problems. Literature survey indicates that efforts are being made for optimization of length of reinforcement for overall economy. The present paper details an analysis to optimize the length of geosynthetic reinforcement from the face or near end of the slope with respect to its location to obtain the desired minimum factor of safety. Unreinforced and reinforced slopes are analyzed using Morgenstern-Price method to obtain critical factors of safety. The effect of providing geosynthetic reinforcement layer in shifting the critical slip circle has been identified and quantified. Consequently relatively smaller magnitude of force gets mobilized in the reinforcement.
Journal of Geotechnical and …, 1998
Geotechnical and Geological Engineering, 2003
A geogrid reinforced steep slope was built and monitored during construction and during the first... more A geogrid reinforced steep slope was built and monitored during construction and during the first ten months of service. The slope is located between Régua and Reconcos in the new Portuguese main itinerary, IP3, and is a part of reestablishment 2. The reinforced slope has an extension of about 206.2 m, is in curve and the reinforced area reaches a maximum height of about 19.6 m in the outside curve slope at 150.0 m of extension (km 0+150). The monitored slope cross section is at km 0+150. The reinforcements are high density polyethylene geogrids;. materials with different tensile strength values were used. The reinforcement strains were measured at three reinforcement levels using linear extensometers. The soil vertical stresses were recorded using load cells. The internal horizontal displacements of the slope were recorded using two inclinometer tubes. The face displacements were recorded topographically in points spaced approximately 1.2 m vertically along the face of the slope on the km 0+150 cross section. The reinforced slope behaviour was observed during a period of about 13 months, which includes three months of construction period. This way it was possible to obtain information about the slope behaviour during and after construction (the first 10 months of service). The behaviour of the observed reinforced slope is characterized by: low values of face displacements, slope internal horizontal displacements and reinforcement strains; change of the face displacements configuration at the end of construction during service;tendency to stabilization of the horizontal displacements in a relatively short period of service; change, during service, of the position of the line passing through the points of the reinforcements where maximum strains were recorded. The reinforced slope behaviour express the conservative design of Equilibrium Limit methods and encourage the research on new design methods for geosynthetic reinforced soil systems.
Journal of Geotechnical Engineering, 1989
... and instructive over-view of the many aspects associated with geosynthetics reinforcement is ... more ... and instructive over-view of the many aspects associated with geosynthetics reinforcement is given ... is adopted from a simplified limit-state stress analysis when geo-synthetic reinforced walls are ... to overestimate tx, resulting in a conservative selection of a geosynthetic based on ...
Conference Presentations by Akshay Jha
Proceedings of the 19th International Conference on Soil Mechanics and Geotechnical Engineering, Seoul , 2017
Steepening of slopes for construction of rail/road embankments or for widening for other civil en... more Steepening of slopes for construction of rail/road embankments or for widening for other civil engineering structures is a necessity for development. Use of geosynthetics for steep slope construction or repair of failed slopes considering all aspects of design and environmental considerations could be a viable alternative to this problem. Literature survey indicates that some efforts were made for optimization of length of reinforcement. The present paper details an analysis to optimize the length of geosynthetics from the face or near end of the slope with respect to its location, length and combination of multiple layers of reinforcement to obtain the desired minimum factor of safety for a steep slope. Steep unreinforced and reinforced slopes are analyzed to obtain critical factors of safety. The effect of providing geosynthetic layer in shifting the critical slip circle has been identified and studied. The effect of interaction between layers of reinforcement has been identified and quantified.
Lecture notes in civil engineering, Dec 11, 2022
Indian Journal of Geosynthetics and Ground Improvement, 2018
Lecture Notes in Civil Engineering
Analysis of earth slopes is one of the oldest geotechnical engineering problems that engineers ha... more Analysis of earth slopes is one of the oldest geotechnical engineering problems that engineers have been dealing with using various techniques. The methods can be classified as limit equilibrium methods (LEM), finite element method (FEM) based on c and φ reduction, finite difference method (FDM), combination of FEM and LEM, limit analysis (LA), etc. Geosynthetic reinforcement of earth slope results in reduction in the land requirement and preservation of natural resources (land and backfill requirements) apart from time and cost. Designing geosynthetic reinforced slope with minimum length of geosynthetics leads to further economy. Jewell et al. [7], Bonparte et al. [3], and Verduin and Holtz [16] present design methods for earth slopes reinforced with geotextiles or/and geogrids using LEM assuming different types of failure surfaces such as circular or/and bilinear wedges. Jewell et al. [7] used limit equilibrium analysis and local stress calculation for design of reinforced slope. Jewell [8] presented revised design charts for steep slopes valid for all polymer reinforcement materials. These revised charts lead to savings of the order of 20-30% in reinforcement quantity. Leshchinsky [9] and Leshchinsky et al. [12] used log spiral failure mechanism to determine the required reinforcement long-term strength. Zhao [17] and Michalowski [14] present kinematic limit analysis solutions for the stability
Lecture Notes in Civil Engineering, 2019
The present paper analyses reinforced steep slope to optimize the length of geosynthetic reinforc... more The present paper analyses reinforced steep slope to optimize the length of geosynthetic reinforcement from the face or near end of the slope with respect to its location, length and combination of multiple layers of reinforcement to obtain the desired minimum factor of safety. In case of walls, the reinforcement needs to extend up to and be tied to wall face due to functional requirement. But in case of slopes, no such requirement exists and hence curtailment of reinforcement from face end is feasible. The effect of providing geosynthetic layer in shifting the critical slip circle has been studied. The interaction between layers of reinforcement has been identified, modelled and quantified. The study facilitates understanding the mechanics of reinforcing slopes which is very different from that of reinforced soil walls.
Slope failures lead to loss of life and damage to property. Slope instability of natural slope de... more Slope failures lead to loss of life and damage to property. Slope instability of natural slope depends on natural and manmade factors such as excessive rainfall, earthquakes, deforestation, unplanned construction activity, etc. Manmade slopes are formed for embankments and cuttings. Steepening of slopes for construction of rail/road embankments or for widening of existing roads is a necessity for development. Use of geosynthetics for steep slope construction considering design and environmental aspects could be a viable alternative to these issues. Methods developed for unreinforced slopes have been extended to analyze geosynthetic reinforced slopes accounting for the presence of reinforcement. Designing geosynthetic reinforced slope with minimum length of geosynthetics leads to economy. This chapter presents review of literature and design methodologies available for reinforced slopes with granular and marginal backfills. Optimization of reinforcement length from face end of the sl...
Geotechnical Engineering Journal of the SEAGS & AGSSEA , 2018
Steepening of slopes for construction of rail/road embankments or for widening for other civil en... more Steepening of slopes for construction of rail/road embankments or for widening for other civil engineering structures is a necessity for development. Use of geosynthetics for steep slope construction or repair of failed slopes considering all aspects of design and environment could be a viable alternative to these problems. Literature survey indicates that efforts are being made for optimization of length of reinforcement for overall economy. The present paper details an analysis to optimize the length of geosynthetic reinforcement from the face or near end of the slope with respect to its location to obtain the desired minimum factor of safety. Unreinforced and reinforced slopes are analyzed using Morgenstern-Price method to obtain critical factors of safety. The effect of providing geosynthetic reinforcement layer in shifting the critical slip circle has been identified and quantified. Consequently relatively smaller magnitude of force gets mobilized in the reinforcement.
Journal of Geotechnical and …, 1998
Geotechnical and Geological Engineering, 2003
A geogrid reinforced steep slope was built and monitored during construction and during the first... more A geogrid reinforced steep slope was built and monitored during construction and during the first ten months of service. The slope is located between Régua and Reconcos in the new Portuguese main itinerary, IP3, and is a part of reestablishment 2. The reinforced slope has an extension of about 206.2 m, is in curve and the reinforced area reaches a maximum height of about 19.6 m in the outside curve slope at 150.0 m of extension (km 0+150). The monitored slope cross section is at km 0+150. The reinforcements are high density polyethylene geogrids;. materials with different tensile strength values were used. The reinforcement strains were measured at three reinforcement levels using linear extensometers. The soil vertical stresses were recorded using load cells. The internal horizontal displacements of the slope were recorded using two inclinometer tubes. The face displacements were recorded topographically in points spaced approximately 1.2 m vertically along the face of the slope on the km 0+150 cross section. The reinforced slope behaviour was observed during a period of about 13 months, which includes three months of construction period. This way it was possible to obtain information about the slope behaviour during and after construction (the first 10 months of service). The behaviour of the observed reinforced slope is characterized by: low values of face displacements, slope internal horizontal displacements and reinforcement strains; change of the face displacements configuration at the end of construction during service;tendency to stabilization of the horizontal displacements in a relatively short period of service; change, during service, of the position of the line passing through the points of the reinforcements where maximum strains were recorded. The reinforced slope behaviour express the conservative design of Equilibrium Limit methods and encourage the research on new design methods for geosynthetic reinforced soil systems.
Journal of Geotechnical Engineering, 1989
... and instructive over-view of the many aspects associated with geosynthetics reinforcement is ... more ... and instructive over-view of the many aspects associated with geosynthetics reinforcement is given ... is adopted from a simplified limit-state stress analysis when geo-synthetic reinforced walls are ... to overestimate tx, resulting in a conservative selection of a geosynthetic based on ...
Proceedings of the 19th International Conference on Soil Mechanics and Geotechnical Engineering, Seoul , 2017
Steepening of slopes for construction of rail/road embankments or for widening for other civil en... more Steepening of slopes for construction of rail/road embankments or for widening for other civil engineering structures is a necessity for development. Use of geosynthetics for steep slope construction or repair of failed slopes considering all aspects of design and environmental considerations could be a viable alternative to this problem. Literature survey indicates that some efforts were made for optimization of length of reinforcement. The present paper details an analysis to optimize the length of geosynthetics from the face or near end of the slope with respect to its location, length and combination of multiple layers of reinforcement to obtain the desired minimum factor of safety for a steep slope. Steep unreinforced and reinforced slopes are analyzed to obtain critical factors of safety. The effect of providing geosynthetic layer in shifting the critical slip circle has been identified and studied. The effect of interaction between layers of reinforcement has been identified and quantified.