6/28/2018. Major Geotechnical Engineering Research Projects. Major Geotechnical Engineering Research Projects. Major Area of Research

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1 2 Major Geotechnical Engineering Research Projects Dr. Arindam Dey Geotechnical Engineering Division Department of Civil Engineering Indian Institute of Technology Guwahati Research vistas Geophysical investigation for subsoil stratigraphy through Active, Passive Roadside and Passive Remote MASW Survey Jumrik Taipodia, Dipjyoti Baglari (PhDs) and Shibayan Biswas (MTech) Dynamic characteristics of soils through Cyclic Triaxial tests Dr. Shiv Shankar Kumar (PhD) Slope stability, Foundations on slopes, Landslide Hazard Assessment and Mitigation Rubi Chakraborty, Rana Acharyya, Chiranjib Prasad Sarma (PhDs), and Abhijit Anand (MTech) Analysis of Dams and Embankments Priyanka Talukdar (PhD) and Madhurita Sawant (MTech) Ground response analysis Madhulatha Boga (PhD) and Devdeep Basu (MTech) 3 Major Geotechnical Engineering Research Projects Research vistas Soil-structure interaction for Bridges and Building foundations Nishant Sharma, Debasmita Pal and Emte Ajom (PhDs), Ananta Sinha (MTech) Optimal design and analysis in geotechnical engineering Sukleshwar Boro (PhD) Pavement Geotechnics Ishan Boro (PhD) and Lokesh Chaudhary (MTech) Rock slope stability and Rock engineering Amalesh Jana and Aswathi C K (MTechs) Preloading and PVDs for soft soil improvement Dr. Giridhar Rajesh Bande and Sai Kiran Chukka (MTechs) Foundation and Retention systems Michael Koch, Naveen Kumar, Milind Patil and Paramveer Rawat (MTechs) 4 Major Area of Research GEOPHYSICAL INVESTIGATION MASW apparatus comprising 24 channel seismograph 4.5 Hz geophones and their connector cables 10 kg sledgehammer and 40 kg Propelled Energy Generator (PEG) Striker plates (Cast Steel and Rubber) and Trigger sensors Seismic borehole equipments (Cross-hole, Up-hole and Down-hole) Ballard shear wave generator and 5-D Receptor Sensor 100 m Submersible HydrophoneArray 1

2 5 Multichannel Analysis of Surface Waves (MASW) Non-destructive seismic exploration Subsoil stratigraphy Shear wave velocity profile / Ground stiffness profile 1D, 2D or 3D formats 6 Overall Procedure in MASW in a nutshell Data Acquisition Using active or passive sources, geophones and a seismograph Dispersion Analysis Phase velocity v/s Frequency (or Wavelength) image/curve Inversion Analysis Shear Velocity v/s Depth profile Time domain data FFT Dispersion Frequency domain analysis Vs profile (Vs v/s Depth) Dispersion curve (φ v v/s f ) Inversion analysis 7 Types of MASW Surveys Procedure of generation of waves 8 Typical Records from MASW Quality / Reliability of Vs profile Resolution of dispersion band Active MASW method Controlled impact by the user (Various types of weight drops) Passive MASW methods Passively generated from natural and anthropogenic activities Passive roadside method Traffic sources Passive remote method Microtremors, Tidal activities, Machine vibrations Filtering and Muting Combined Active and Passive Technique Numerical combinations of wavefields or dispersion images 2

3 9 Resolution of Dispersion Band 10 Factors affecting Resolution of Dispersion Band Data acquisition, preprocessing and processing parameters Taipodia et al., Disaster Advances, Experimental investigation Sampling frequency Acquisition time Offset distance Inter-receiver spacing Number of geophone receivers Type of source Number of stacks Striker plate materials Series of recommendations Taipodia et al., Journal of Geophysics and Engineering, Extraction from 2-D Dispersion Image Image processing techniques and Matlab coding Dependency on the choice of the threshold amplitude of dispersion band Enhanced error for thickened width of the dispersion bands 12 Extraction from 3-D Dispersion Image Image processing techniques and Matlab coding Taipodia et al., Computer and Geotechnics (Under review) 3

4 13 A new 4-lane (1.2 km) carriageway bridge over Jiya-Bharali River bed National Highway and Infrastructure Development Corporation Limited (NHIDCL) Located in Tezpur District, Assam state Connects NH-52A and NH-37 Project completed with Simplex Infrastructures Ltd 14 Superstructure span 1.2 km - 24 Piers - 2 Abutments Pier spacing 48 m MASW test - Active mode 10 kg sledge hammer impact as seismic source 4.5 Hz Geophones Mass of land from piers 1-4 Submerged under river water Roll Along method of Active MASW test Shifting equipment from pier to pier with a 12 m overlap 15 Bandpass filtering with mild temporal muting 16 Dispersion image stacking to enhance resolution Dispersion image from single record Raw Data Filtered and Muted Data Dispersion image after stacking 4-records 4

5 17 Automated extraction of dispersion curve and Inversion 18 MASW Survey at a Bridge Site Profiles obtained as a roll-along method Extracted multimodal dispersion curve 1D Shear wave velocity profile 19 2-D shear wave velocity profile Taipodia et al., Pure and Applied Geophysics (Under review) 20 Major Area of Research HILL-SLOPE STABILITY ANALYSIS IN LOCAL AND REGIONAL SCALE 5

6 21 Landslide Analysis on a Local Scale Slope Stability Analysis 22 Hill-Slope Stability Chakraborty and Dey,, NESGC, 2016 Effect of hydraulic and pseudo-static conditions on the stability of hill slope Hill Slope H δ β Bedrock h Static Dry Static WT Pseudo-Static Dry Pseudo-Static WT 23 Hill-Slope Stability Toe-cutting (A typical slopeβ=30 0,φ=20 0 ) Dry Hill Slope H δ Project for PWD Arunachal Pradesh β Bedrock Dry Pseudo-static static h 24 Hill Slope H δ β h Bedrock Hill-Slope Stability Statistical Regression Analysis WT Pseudo-static static X1= c X2= φ X3 = β X4 = δ X5 = h FoS = c φ β δ h c φ β δ h cφ φβ βδ δ h cφβ φβδ βδ h δ hc cφβδ φβδ h βδ hc cφβδ h 5 2 6

7 25 Probabilistic Analysis of Landslides Deterministic framework of analysis Natural tendency to define soil property by a single value Defines a specific safety factor Obtaining the analytical safety factor based on soil parameters is NOT GUARANTEED 26 Probabilistic Analysis of Landslides Probabilistic framework of analysis Defines a margin of safety and a probability of failure instead of a specific safety factor Soil parameters are defined as random variables with a probability distribution of occurrence (single or joint probability) No parameters affecting landslides are deterministic All are uncertain in their determination All are uncertain in their effect and functioning Heterogeneity and Uncertainty are the inherent properties of soil parameters 27 Probabilistic Analysis of Toe Cutting on Hill Slopes A case study 40 m high slope with inclination 40 subjected to vertical toe cutting c mean = 40 kpa,φ mean = 27.5 LEM Morgenstern-Price method with MCS 28 Probabilistic Analysis of Landslides Random Finite Element Method (RFEM) FE based on Random Field Generation for parameters Accounts for spatial variability Parameters are allotted to each grid based on specified correlation length No prior assumption of slip surface required for failure Dry Dry Pseudo-static static 7

8 29 Probabilistic Analysis of Landslides Influence of correlation length in random field Isotropic correlation Formation of parameter pockets Anisotropic correlation Formation of stratified layers Local scale stability analysis Influence of correlation length Log-normal pdf with a CoV of 0.2 bt = 0 θx = 10.0 θy = 2.0 θx = 5.0 θy = 5.0 θx = 10.0 θy = 10.0 θx = 1.0 θy = Spatial Variability Sarma et al., 14IACMAG, 2014 Simulation of spatial variability of soil shear strength parameters 31 Spatial Variability in Regional Scale 32 Sarma et al., Landslides (Communicated) Salient variable parameters Shear strength parameters Regional Scale Analysis Landslide Susceptibility of Guwahati City Landslide Hazard Zonation and Landslide Susceptibility Studies Permeability characteristics Geological and geomorphological variability Rainfall distribution SHALSTAB, TRIGGRS, SINMAP, Physically Based Models GIS platform for Digital Elevation Models (DEM) Mangan, Sikkim Shuttle Radar Topography Mission (SRTM) of 1 arc-s resolution DEM 8

9 33 Sarma et al., Landslides (Communicated) Regional Scale Analysis Landslide Susceptibility of Guwahati City Landslide Hazard Zonation Regional Scale Analysis Landslide Susceptibility of Guwahati City and Landslide Susceptibility Studies 1 9 SHALSTAB, TRIGGRS, SINMAP, Physically Based Models Derived elevation and slope maps Sarma et al., Landslides (Communicated) Landslide Hazard Zonation and Landslide Susceptibility Studies SHALSTAB, TRIGGRS, SINMAP, Physically Based Models Map of catchment areas To identify the volume of water flowing in or flowing out of the particular grid Slope Maps Catchment Area Map Sarma et al., Landslides (Communicated) Regional Scale Analysis Landslide Susceptibility of Guwahati City Landslide Hazard Zonation SHALSTAB, TRIGGRS, SINMAP, Physically Based Models Map of steady state recharge for a single rainfall event Regional Scale Analysis Landslide Susceptibility of Guwahati City Landslide Hazard Zonation and Landslide Susceptibility Studies and Landslide Susceptibility Studies SHALSTAB, TRIGGRS, SINMAP, Physically Based Models Stability map for a single rainfall event Stability Index Map Based on infiltration characteristics of the soil Steady State Recharge Map Sarma et al., Landslides (Communicated) 9

10 37 Regional Scale Analysis Landslide Susceptibility of Guwahati City Incorporation of soil depth variability Sarma et al., Landslides (Communicated) Corestones Sarma et al., Landslides (Communicated) Variation of weathered soil thickness and slope angle Laterite 25 Common stratigraphic features at Guwahati region Monthly mean rainfall based on 100 years data ( ) at Kamrup metropolitan 20 Depth of Soil Formation IDF curves for Guwahati region Estimated Soil Depth (H) H = 25.0e-0.075β Soil Depth from Bore-hole data Saprolite Regional Scale Analysis Landslide Susceptibility of Guwahati City Incorporation of rainfall variability Slope Angle in Degrees Sarma et al., Landslides (Communicated) Regional Scale Analysis Landslide Susceptibility of Guwahati City Landslide Hazard Zonation SHALSTAB, TRIGGRS, SINMAP, Physically Based Models Soil thickness map Regional Scale Analysis Landslide Susceptibility of Guwahati City Landslide Hazard Zonation and Landslide Susceptibility Studies and Landslide Susceptibility Studies Change of landslide zones with rainfall duration at Guwahati ciy Ongoing project for next 2 years with DST: Rainfall induced landslide hazard assessment study at Guwahati city and consequent Risk Assessment FoS map after 48 hr rainfall FoS map at Dry state Soil thickness map 10

11 41 Acknowledgements to my Student Battalion PhDs 42 Acknowledgements to my Acdemic Partners Mtechs Acknowledgements to my Industry and Project Partners Btechs and Interns 43 Thank You for Patient Hearing