Sima Ghosh

Seismic Active Earth Pressure on the Back of Battered Retaining Wall Supporting Inclined Backfill

Knowledge of seismic active earth pressure behind a rigid retaining wall and its point of application are very important to the design of retaining walls in earthquake-prone regions. This paper presents a detailed study on the seismic active earth pressure and its point of application behind a nonvertical, rigid retaining wall supporting inclined, cohesionless backfill, using pseudo-dynamic analysis that is more realistic to representing the time and phase difference within the backfill. A planar failure surface is considered in the analysis. The effects of soil and wall friction angle, wall and backfill surface inclination, and horizontal and vertical earthquake acceleration on the active earth pressure have been explored. Results are presented in both tabular and graphical nondimensional form, including comparison with other available methods to highlight the realistic nonlinearity of seismic active earth pressure distribution.

Improved backtracking search algorithm for pseudo dynamic active earth pressure on retaining wall supporting c- backfill

Display Omitted New self-adaptive control parameters setting are incorporating to Backtracking Search Algorithm for improving the performance of the algorithm.To validate the performance of the proposed algorithm, it is applied to solve twenty five CEC2005 test functions.The proposed method has been successfully applied to obtain the active earth pressure on retaining wall supporting c- backfill using the pseudo dynamic method. Optimization algorithms are effective and powerful tools for solving the non-linear optimization problems. Backtracking Search Optimization Algorithm (BSA) is a newly proposed Evolutionary Algorithm (EA) and has been applied to optimize different complex optimization problems in science and engineering. In the present study, a new adaptive control parameter based Improved Backtracking Search Optimization Algorithm (IBSA) is suggested. Due to the validation of the suggested method, it has been applied to CEC2005 benchmark functions and the simulation results are compared with different existing algorithms. Also, it has been used to determine active earth pressure on retaining wall supporting c- backfill using the pseudo dynamic method. Simulation result shows that the proposed method is suitable to solve such type of problems and the results obtained are found satisfactory.

Pseudo-dynamic evaluation of passive response on the back of a retaining wall supporting c-Φ backfill

The study presents a rational analytical approach to obtain the seismic passive response of an inclined retaining wall backfilled with horizontal c-Φ soil. Pseudo-dynamic analysis is carried out to obtain the seismic passive response. Here in this analysis, the critical wedge angle is a single one irrespective of weight, surcharge and cohesion and this fact satisfies the field situation in a more realistic manner. A planer failure surface is considered in the analysis. The effect of soil and wall friction angle, wall inclination, horizontal and vertical earthquake acceleration on the passive resistance and the variation of passive earth pressure along the height of the wall have been explored. A comparison to pseudo-static and other available methods have been made to highlight the non-linearity of seismic passive earth pressure distribution.

Parameters Optimization of Geotechnical Problem Using Different Optimization Algorithm

Abstract Recently, many heuristic global optimizations successfully applied in various types of real life problems. The majority of these algorithms had not been applied to solve civil engineering problem, especially in the field of geotechnical engineering. In this paper a study has been made to use the different optimization techniques (HSA, TLBO, and PSO) and find out the solution for one civil engineering problem. Civil engineering structure, retaining wall is taken for solution and the solution is done for total active force on the back of a retaining wall supporting c–Φ backfill under pseudo-static seismic force using the three optimization techniques as mentioned above. A detailed comparative study has also been made with the values obtained from the present study and tthe values available in different literatures. A detailed parametric study is also done to see the effect of different optimization techniques on the variation of different parameters.

Analysis of slope considering circular rupture surface

Determination of stability under seismic loading condition of soil slope is one of the important findings for geotechnical engineers. Here, in this paper, a homogeneous soil slope considering circular failure surface has been analyzed under the influence of pseudo-dynamic inertia forces and surcharge load by limit equilibrium method. The Fellenius line is used to locate the center of most critical circle and factor of safety has been found through the application of force equilibrium. The effects of variation of parameters such as horizontal and vertical seismic accelerations, soil friction angle and slope angle on factor of safety are presented.

Nonlinear Failure Surface and Pseudodynamic Passive Resistance of a Battered-Faced Retaining Wall Supporting c-Φ Backfill

AbstractIn the present analysis, a methodology is developed to calculate the pseudodynamic passive resistance on the back of a battered-faced retaining wall supporting cohesive-frictional backfill using the horizontal slice method and limit-equilibrium principle. The results are presented in both tabular and graphical nondimensional form. The analysis identifies a nonlinear rupture surface that depends on the wall-backfill parameters. The effects of wide variations in the parameters, such as the wall inclination angle (α), wall friction angle (δ), soil friction angle (Φ), shear-wave velocity (Vs), primary wave velocity (Vp), and horizontal and vertical seismic accelerations (kh, kv) on the seismic passive resistance coefficients have been studied.

A Hybrid Symbiosis Organisms Search algorithm and its application to real world problems

In this paper, a new hybrid algorithm, Hybrid Symbiosis Organisms Search (HSOS) has been proposed by combining Symbiosis Organisms Search (SOS) algorithm with Simple Quadratic Interpolation (SQI). The proposed algorithm provides more efficient behavior when dealing with real-world and large scale problems. To verify the performance of this suggested algorithm, 13 (Thirteen) well known benchmark functions, CEC2005 and CEC2010 special session on real-parameter optimization are being considered. The results obtained by the proposed method are compared with other state-of-the-art algorithms and it was observed that the suggested approach provides an effective and efficient solution in regards to the quality of the final result as well as the convergence rate. Moreover, the effect of the common controlling parameters of the algorithm, viz. population size, number of fitness evaluations (number of generations) of the algorithm are also being investigated by considering different population sizes and the number of fitness evaluations (number of generations). Finally, the method endorsed in this paper has been applied to two real life problems and it was inferred that the output of the proposed algorithm is satisfactory.

Pseudo-dynamic analysis for bearing capacity of foundation resting on c–Φ soil

Abstract Estimation of seismic bearing capacity of foundation in earthquake prone area is an important parameter in the design of any substructure. This paper presents a pseudo-dynamic approach for calculating the seismic bearing capacity of shallow strip footing resting on c–Φ soil using limit equilibrium method. Considering the Coulomb failure mechanism, the effect of wall friction angle and soil friction angle, soil cohesion, shear wave and primary wave velocity, and horizontal and vertical seismic accelerations are taken into account to evaluate the seismic bearing capacity of foundation. In this paper, the seismic bearing capacity presents in a single coefficient (Nγ e) for the simultaneous resistance of unit weight, surcharge, and cohesion, which is reasonable and easy to use. The results obtained from the present analysis thoroughly compared with the existing values in the literature and the significance of the present methodology for designing the shallow strip footing is discussed.

Pseudo-static Analysis of Reinforced Earth Retaining Wall considering Non-linear Failure Surface

The seismic stability of reinforced earth has been investigated in this paper using pseudo-static method of analysis considering horizontal and vertical seismic acceleration with non-linear failure surface. The sliding wedge is divided into a number of horizontal slices to determine the strength and length of the geo-synthetic reinforcement for seismic internal stability of battered face rigid retaining wall supporting c-Φ backfill. Results are presented in graphical form representing the required length of geo-sythetic reinforcement under seismic condition to maintain the internal stability of reinforced soil. The influences of horizontal and vertical seismic acceleration, soil friction angle, cohesion, adhesion and wall inclination angle on the required length of the geo-sythetic reinforcement have been studied. From the present study it is seen that the required length of geo-synthetic reinforcement increases due to increase in the value of seismic accelerations.

Analysis of slope using modified pseudo-dynamic method

Seismic design of slope is an important aspect in earthquake-prone areas to resist devastation due to earthquake load. This study presents the seismic stability analysis of homogeneous soil slope in which modified pseudo-dynamic method adopting limit equilibrium approach has been used. Results are presented in tabular form, which will serve as essential design parameters. Parametric studies show effects of soil properties and seismic forces on safety of slope. In addition, the required reinforcement strength against failure under seismic loading is evaluated and presented in figures that are useful to design reinforced slope.