Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

In case of cut slope made in cemented soil or stiff clay, failure is to be expected due to the detachment of bonds (brittle fracture). This field scenario could be simulated by performing triaxial extension test on these types of soils under low effective stress state. This paper presents the results of a series of triaxial compression and extension tests performed on artificially prepared cemented soil and remolded clay in the low stress range. Testing revealed that the mode of failure for cemented soil is different in compression (shear failure) and extension (brittle failure). For cemented soil, shear resistance in extension is found to be less dependent on the normal stress and the resistance is mostly due to the cementation bonds. But in remolded clay, shear resistance is found to be proportional to the effective normal stress at failure. Therefore the use of shear parameters based on compression tests may not be apposite for the stability analysis of cut slopes made in cemented soil. In such cases, failure criteria may be better taken as the difference in principal stresses.

Department of Civil Engineering

Electronic Journal of Geotechnical Engineering

Failure of cemented soil under decreasing effective stress

Kuttanad region is the largest agricultural area in the state of Kerala, India. The soil in this region is dark brown colored highly compressible clay with high organic content. Few studies are reported in this clay even though a significant number of substructure and embankment failures have occurred in the past. This paper presents the details and results of an experimental investigation conducted to study the influence of organic content on the physical and engineering properties of the Kuttanad clay. The test results showed that the organic content has considerable adverse effect on the geotechnical properties of this clay. Plasticity and compressibility characteristics were increased with increase in organic content. The shear strength of the clay was greatly decreased with increase in organic content. However negligible variation in maximum dry density was observed with increase in organic content. © 2011, ejge.

World University root node

Effect of organic content on geotechnical properties of Kuttanad clay

In current practice, driven piles/drilled shafts are constructed in a group at 3D center to center (c/c) spacing to minimize group interference (i.e., group efficiency factor ~ 1) as well as reduce the cost of the reinforced concrete cap. Presently, group efficiency factors for a number of new foundation types, e.g., post-grouted drilled shafts and jet-grouted piles, are unknown. This research looked into the group interaction of post-grouted drilled shafts and jet-grouted piles at typical 3D spacing. Two sets of group tests for grout-tipped drilled shafts and jet-grouted piles were performed in the Florida Department of Transportation (FDOT) test chamber in medium dense sands. The experimental top down group testing revealed that the jet-grouted piles behaved as a block at 3D spacing, whereas post-grouted drilled shafts acted independently of one another, i.e., no group interaction. A group interaction factor, as well as an analytical approach for predicting load versus displacement for single or group of jet-grouted piles, is suggested. In the case of the grout-tipped drilled shafts, the grout pressure always resulted in an upward flow of grout alongside the shaft which increased both the side and tip areas. The increased areas and grout tip preload were the three factors identified with the increased shaft and group resistance. Due to uncertainty in estimating areas, a conservative design approach for assessing single and group capacities of post-grouted drilled shafts at 5% displacement is proposed. Finally, the use of stage grouting to assess the increase in shaft capacity (skin and tip) is suggested.