Liquefaction Analysis and Foundation Design for Transient Loading

Abstract

Liquefaction is one of the major aspect in geotechnical earthquake engineering, which largely affects the stability of substructure and subsequently the super structure when subjected to a dynamic load. Liquefaction leads loosening of shear strength of soil to a negligible value for all engineering purposes. Liquefied soils tend to behave as fluid and is unable to support a structure. Liquefaction related issue evolved initially in the wake of two major earthquake occurred in Niigata and Alaska earthquake on 1964. Liquefaction has been a source of much damage in the past earthquakes (e.g. Niigata and Alaska earthquakes of 1964, Kobe earthquake of 1995, Kocaeli-Turkey and Chi-Chi earthquakes of 1999, Bhuj earthquake 2001). Henceforth, liquefaction analysis must be carried out to assess the probability of liquefaction during an event of earthquake.

As per IS 1893 (Part-I):2016 liquefaction analysis can be carried out using results of Standard Penetration Test [SPT], Static Cone Penetration Test [SCPT]. Standard Penetration Test as per IS 2131:1981 and Static Cone Penetration Test [SCPT] as per IS 4968 (Part-III):1976, was conducted at Nirma University campus, Ahmedabad. Methodology adopted for the analysis has been discuss step-wise with the help of simplified flow chart and results of liquefaction analysis are compared and correlation is established between SPT and SCPT results. Dynamic Cone Penetration Test [DCPT] was also been done at Nirma University campus, Ahmedabad to established correlation between various test conducted. Furthermore, Foundation is designed for transient loading. A system subjected to periodic excitation has two components of motion, the transient and the steady state. Transient vibration is caused by earthquake, blast, impacts, suddenly dropping of loads etc.