ESTIMATION OF INITIAL VOID RATIO OF CONSOLIDATED CLAY BASED ON ONE-DIMENSIONAL CONSOLIDATION THEORY

Abstract

Many stupas located within the sacred historical site of Ayutthaya, Thailand are inclined. It is
important to understand their ground conditions and causes of inclination in order to design appropriate
conservation countermeasures for these precious cultural assets. Soil investigations were conducted at four
points around the inclined stupa of Wat Krasai, located outside the World Heritage Site ”Historic City of
Ayutthaya” in 2013 and 2016. Three key soil layers appear to be responsible for the inclination of this stupa: the
second soft clay layer, the third loose silty sand layer, and the fourth hard clay layer. The inclination of this stupa
increased as the thickness of the second soft clay layer. Thus, we assumed that the cause of stupa inclination and
disproportionate settlement of the stupa was only the second soft clay layer. The amount of settlement and the
initial void ratio of this second layer were estimated using the consolidation calculation formula based on
Terzaghi's one-dimensional consolidation theory. The results of this study indicate that the amount of settlement
is not exactly proportional to the thickness of the second soft clay layer, or that the void ratio is inhomogeneous
in the layer. The calculation is conducted in four directions, north, south, east, and west, and the maximum
settlement and the initial void ratio of the second soft clay layer are estimated at approximately 6.9 m and
between 1.46 and 2.48 at the north side of the stupa, respectively.