Research @ Glance · Dynamic Response of Vertical and Batter Single and Group Piles · Seismic Response and Deformation Characteristics of Nailed Soil Slopes · Analysis of Gravity Dam-Foundation System for Jointed Rock Foundations with Shear Seams · Optimum Design of Reinforced Soil Walls (RSW) for Vertical Expansion of MSW Landfills – A Reliability Based Approach · Dynamic Response of Block Foundations Subjected to Vibrations Induced by Two Rotating Machines · Load Transfer Mechanism of Connected and Disconnected Piled Rafts in Sand · Railway Research
Dynamic Response of Vertical and Batter Single and Group Piles
In last few years, an extensive effort has been made through the research to provide the guidelines for the prediction of the stiffness and damping of single and group piles of various configurations in different soil conditions for rotating machines used for nuclear power plants, petrochemical industry and offshore structures. The effect of soil-pile separation and boundary zone parameters on the frequency-amplitude response of the vertical and batter piles under both vertical and coupled excitation of the rotating machines were studied in details through field testing of scaled pile foundations and numerical studies. Finally, the design charts and formulas were developed to predict the dynamic response of piles correctly in the nonlinear soil and to safe design of pile foundations under the rotating machine induced vibration. Due to the hard work put in by the research team working with me, the guideline has gained a wide acceptance with various researchers worldwide.
		Experimental investigations on instrumented vertical and batter single pile and pile group in the field to obtain: Frequency-amplitude response  Soil-pile separation length Dynamic axial force and bending moments Prediction of the boundary zone soil parameters Development of model using Continuum approach to predict the nonlinear dynamic frequency-amplitude response and the boundary zone parameters of pile-soil system for vertical and coupled modes of vibrations
“Dynamic Response of Pile Foundations in Nonlinear Soil Media with Non-Reflective Boundary under Vertical Excitation of Rotating Machine” Department of Atomic Energy (DAE) at Board of Research in Nuclear Sciences (BRNS), Government of India, PI: Bappaditya Manna
Seismic Response and Deformation Characteristics of Nailed Soil Slopes
Significant contributions has been made in the development of the failure mechanism of nailed soil slope under earthquake loading condition and useful guidelines for prediction of the slope and crest deflection, nail forces and estimation of the factor of safety of nailed soil slopes for seismic loading. These guidelines will useful for slope stabilization and prevent landslides in hilly area.
To understand the seismic behaviour (maximum lateral displacements and maximum nail forces) of model soil slopes without and with nails with the help of shaking table tests and numerical studies To study the maximum lateral displacements at various heights of the facing, maximum crest settlement and acceleration amplification at crest for both unreinforced and reinforced soil slopes under seismic loading To develop the failure mechanism of both unreinforced and reinforced soil slopes and delineate the effect of slope angle, nail inclination, nail length and slope facing on the behaviour of model soil slopes under the seismic loading condition
“Seismic Response and Deformation Characteristics of Nailed Soil Slopes - Shaking Table Testing and Analysis” Department of Science & Technology (DST), Ministry of Science & Technology, Government of India, PI: Bappaditya Manna
Analysis of Gravity Dam-Foundation System for Jointed Rock Foundations with Shear Seams
An attempt has been also made to prepare design chart of dam-foundation system resting on rock foundation with various set of joints for various hydro power projects. The effect of various parameters such as joint set orientation, joint set spacing, joint normal and joint shear stiffness, strength properties of seam are studied and summarized. The novelty of this research is to provide optimum depth of plug for the treatment of shear seam, in a foundation with various set of joints.
To propose equations calculating stress–deformation response of a gravity dam-foundation on jointed rock and to calculate depth of concrete plug for dental treatment Collection of data for 40 Detailed Project Reports in Himalayan region where gravity dams are under construction or proposed to be constructed to study the joint in the foundation The prime objective is to investigate the influence of various joint orientations in the rock mass on the dynamic response of the dam under static and dynamic loading conditions as per IS: 6512
	Important Findings: Actual variation of uplift pressure are non-linear below dam base – not triangular as suggested by IS 6512 As product of normal stiffness and joint spacing approach the modulus of intact rock of foundation, the effect of stiffness ratio becomes negligible for all joint angle Effect of joint stiffness ratio on the Principal stresses are least for 90° joints, Maximum for horizontal joints
Optimum Design of Reinforced Soil Walls (RSW) for Vertical Expansion of MSW Landfills – A Reliability Based Approach
In the last few decades, the waste generation has increased significantly in India as well as across the world. My research team has also worked on stability of vertical expansion of municipal solid waste (MSW) landfills by constructing reinforced soil wall (RSW). This study presents a framework for estimating the series system reliability index for the satisfactory design of RSW for a MSW landfill expansion by considering the translational failure mechanism. System reliability based design optimization (SRBDO) is used to determine the reliability index against external failure modes, namely sliding, eccentricity and bearing capacity and internal failure modes, namely tension and pull-out failures. This approach has also been used to obtain the optimum dimensions to construct a RSW and to get the optimum number of reinforcements to make the design safe against external as well as internal modes of failure.
	Vertical expansion of municipal solid waste (MSW) landfills by constructing reinforced soil wall (RSW) is a requirement of the present scenario to avoid acquisition of new landfill sites. The safe design of RSW in terms of optimum dimensions to construct a RSW and to get the optimum number of reinforcements for a vertically expanded landfill are proposed for (a) static loading, (b) seismic loading, (c) building up of leachate in landfill and (d) building up of leachate in landfill under seismic loading.
Dynamic Response of Block Foundations Subjected to Vibrations Induced by Two Rotating Machines
The design procedure for a block supporting several unbalanced forces is to combine all the dynamic forces from each rotating component into a single resultant unbalanced force and moment about any axis. Data on the performances of combined machine foundations are scanty particularly when nonlinear response of block foundation is expected under high magnitude of unbalanced forces and moments due to soil nonlinearity. An attempt has been made to investigate the dynamic behaviour of block foundations considering soil nonlinearity subjected to machine-induced vibration with a single machine and two machines by the experimental and analytical study. The effects of various influencing parameters, namely, aspect ratio, mass ratio, excitation intensity, dynamic force ratio, static weight ratio, machine orientation, and embedded condition of the block on the dynamic response of the soil-foundation system are studied. Also, the effect of machine orientation concerning the dynamic forces and moments in different directions on the dynamic response of the soil-foundation oscillator system are investigated in details. The research output would give some direction to the practicing engineers and researchers to design the machine foundations with multiple dynamic loads considering the soil nonlinearity.
						To assess the effect of dynamic force ratio, static weight ratio, and direction of the applied dynamic load on the combined response of two machines mounted on a block foundation Forced vibration tests on a small-scale prototype block foundation subjected to two dynamic loads with different operating frequencies: VZ – VZ, VZ – HX, VZ – HY, HX – HX, HX – HY, HY – HY
Load Transfer Mechanism of Connected and Disconnected Piled Rafts in Sand
Connected piled raft (CPR) foundations are often used for high-rise buildings in which the load carrying capacities of both raft and piles are utilized in a combined way. The innovative concept of disconnected piled raft (DPR) system, where the piles are structurally disconnected from the raft by a granular cushion layer, has immersed as a suitable and economic alternative to the CPRs. In this study, scaled 1g model experiments are performed on CPR and DPR under vertical load to investigate the load transfer mechanisms of both the systems and understand the fundamental difference between these two approaches as far as the foundation stiffness and the pile response are concerned. Settlement-dependent interaction factors between raft and piles in a CPR system are evaluated and a simple mathematical model is proposed to estimate the pile-raft load proportions using these interaction factors and stiffnesses of unpiled raft and pile group. The impacts of thickness and granularity of cushion layer on the behaviour of DPR system and the structural responses of disconnected settlement reducing piles are examined thoroughly and the optimum values of these two defining parameters are obtained on the basis of the experimental findings. The influences of other geometric design parameters such as pile length, pile spacing and raft thickness on the performances of CPR and DPR systems are also studied in a comprehensive manner. Finally, some useful results are provided on the basis of numerical analyses to predict the performance of prototype DPRs subjected to vertical load.
						Important Findings: For CPR, (1) Maximum axial load at pile head; (2) Neutral axis at the top and positive skin friction prevails; (3) The settlements of pile, raft and soil are same at the top For DPR, (1) Maximum load somewhere below the pile head where the neutral axis lies; (2) Soil displaces more than the pile at the upper portion which generates negative skin friction; (3) Negative skin friction at the upper part of the pile and positive skin friction in the remaining portion
“Improvement of S&T Infrastructure 2015 (FIST 2015)” Department of Science & Technology (DST), Ministry of Science & Technology, Government of India, Co-PI: Bappaditya Manna
Developed and Maintained By : Bappaditya Manna; Last Updated on 15.11.2021