Showing papers by "G. R. Dodagoudar published in 2019"

Numerical modelling of rainfall effects on the stability of soil slopes

Abstract: High intensity rainfall leads to slope failures that are initially unsaturated. Rainfall is the main triggering factor for the slope failure; however, the denseness of the soil with associated soil properties has not received adequate attention on the stability of the slopes. In this study, the finite difference analysis of transient water flow through unsaturated–saturated soil is carried out to study the effects of rainfall intensity and duration on pore pressure generation, degree of saturation, slope stability and shear strain increment during rainfall event. A parametric sensitivity analysis is performed considering three rainfall intensities applied over the soil slopes consisting of three different soil states namely loose, medium and dense. Results indicate that the rainfall affects the stability of loose and medium soil slopes much as compared to the dense soil slope. The rain-induced instability is much more in loose soil slope as compared to the medium soil slope.

Finite Element Evaluation of Vertical Bearing Capacity Factors $$N_{c}^{\prime }$$ N c ′ , $$N_{q}^{\prime }$$ N q ′ and $$N_{\gamma }^{\prime }$$ N γ ′ for Ring Footings

Abstract: In this study, the vertical bearing capacity factors $$N_{c}^{\prime }$$ , $$N_{q}^{\prime }$$ and $$N_{\gamma }^{\prime }$$ are evaluated for smooth and rough base ring footings resting on c–ϕ soil using the finite element method. The radii ratio, (ri/ro), is the ratio of internal radius to the external radius of the ring footing, is varied from 0 to 0.75 with an increment of 0.25. The friction angle of the soil is varied from 5° to 35°, dilation angle is zero and the Mohr–Coulomb yield criterion and non-associative flow rule are used. The study is extended for the soil having a friction angle of 35° considering the non-associative flow rule with a dilation angle of 5°. The bearing capacity factors are evaluated considering cohesion, surcharge and unit weight as three separate components. Then the superposition of the three components of the bearing capacity equation is analysed. A numerical example is considered to illustrate the applicability of the finite element analysis by comparing the bearing capacities with those of the Terzaghi’s classical equation. The finite element results are presented in the form of design charts and tables for practical use.

Finite-element analysis of strains in seepage barriers of the earth dam

Abstract: This paper presents the strain profiles obtained along the height of the seepage barriers of the earth dam. The seepage barriers are employed in the permeable dam section in order to obstruct the s...

Landslide Risk Assessment and Mitigation—A Case Study

Abstract: Landslides are defined as down slope movement of rock, debris and earth under the influence of gravity. Slide is one of the most common types of hazards on slopes, which might lead to considerable casualties and economic loss. The study and analysis of slope is essential in understanding their performance and, in particular, their stability, reliability and deformations. The aim of the present study is to analyse the typical slope by varying different soil parameters like cohesion, angle of internal friction, water table and also slope geometry such as slope angle and slope height. The stability of the slope is analysed based on numerical simulation using three geotechnical software namely Slope/W, SV-Slope and Plaxis 2D. The study further is directed towards the assessment of stability of landslide along State Highway-72, near Mahabaleshwar, Maharashtra. The analysis of slope is carried out using Slope/W and Plaxis 2D. It was found through the analysis that the slope was unstable under the saturated condition. In an attempt of suggesting suitable remedial measures for the same, soil nailing is provided for the slope and simulation is carried out using Geo-5/Nailed slope software. As a result, the slope was found stable after the application of soil nailing.

Numerical Analysis of MSE Wall Using Finite Element and Limit Equilibrium Methods

Abstract: Mechanically stabilized earth (MSE) retaining walls are the most suitable design alternatives to the conventional retaining walls due to their simple, rapid, and cost-effective construction, reduced right-of-way acquisition, etc.; hence, the MSE walls are used in many central, state, and private sector projects. But the design and analysis is a challenging task for geotechnical engineers. This paper deals with the study of stability and wall movement of a existing MSE wall constructed on a major state highway in central Texas, using a finite element (FE) analysis and limit equilibrium (LE) slope stability analysis program GEO5 2016. The detailed analyses for both internal and external stabilities were obtained from the finite element and limit equilibrium analysis, with a critical failure surfaces and the wall movement of a MSE wall. The factors of safety obtained from both analyses were compared. The study shows that the factors of safety obtained from finite element and the limit equilibrium analysis, for a given problem, match in an acceptable range with a different critical failure surfaces. Also, this paper deals with the effect of backfill soil and reinforcements on stability and excessive movements of MSE wall.

Experimental Study of Heave Control Technique for Expansive Soil Using Micropiles and Geotextile Layers

Abstract: Heaving of expansive soil is a crucial phenomenon due to their excessive volume changes with variation in moisture regime, which in turn leads to substantial distress to the structures built on them The main objective of this study is to evaluate the effectiveness of micropile and performance of geotextile to resists upward movement of structures built over expansive soil For this study, the expansive clay compacted in a steel box of size 50 cm × 50 cm × 50 cm to a depth of 20 cm and analyzed with two different methods to control heaving of soil Firstly, four micropiles of 16 and 20 mm in diameter were inserted into the soil with and without frictional resistance The micropiles were fastened to the corners of footing of size 15 cm × 15 cm × 05 cm, with nut and bolt system Further, Geotextiles were reinforced below the footing at a vertical spacing of 01B and 03B as single and double layers Then the soil was saturated with water and the upward movement of model footings (swelling) was monitored with time Test results showed that maximum heave reduction was 79% for 20 mm diameter micropiles with frictional resistance

Development of Gutenberg–Richter Recurrence Relationship Using Earthquake Data

Abstract: This paper provides the hazard parameter values from the approach of Gutenberg–Richter recurrence relationship. Considered the total 197 (1819–2016) years sample of earthquakes catalogue are taken to derive Gutenberg–Richter (GR) relationship, for Gujarat, Western India region. Declustering is the process of removal of dependent earthquake events (foreshocks and aftershocks) from an earthquake catalogue, and this was carried out by using a dynamic spatial–temporal windowing technique. These sequences include the declustering of the catalogue, and estimation of completeness periods for different magnitude classes is 3–4, 4–5, 5–6 and ≥6. First, different approaches for estimation of seismicity parameters have been studied and identified with respect to stable continental regions. Second, the importance of dependence of b value (slope of recurrence curve) on different magnitude intervals has been identified for catalogue data available for Western India (WI). Completeness analysis of the earthquake catalogue was performed by both the visual cumulative and Stepp’s methods [1, 2]. Fitted the frequency formula and estimated reliable Gutenberg–Richter (GR) parameters to quantify seismic hazard for Gujarat, WI region.