In‐Situ Stress Measurements in Singapore

Abstract

AbstractIn the year 2008 and 2009, in‐situ stresses were measured in 18 boreholes by the hydraulic fracturing method to determine the present‐day stress state of the shallow crust in Singapore, which provide key parameters for the design and construction of underground tunnels and data for the study of world stress environments. The test results show that at depths ranging from 38.00~56.95 m, the maximum horizontal principal stress σH is 3.45~9.64 MPa, and the minimum horizontal principal stress σh is 2.49~6.28 MPa. The relative stress magnitudes are σH > σh > σv, and the mean values of maximum horizontal principal stress and minimum horizontal principal stress are respectively 5.13 and 3.23 times the vertical stress, implying the horizontal stress is dominant. The magnitudes of the tectonic stress field in the shallow crust of Singapore exhibit heterogeneity, which are low in the north and south and high in the middle. The maximum and minimum principal stresses are both lower than their mean values in the northern end, and are well matched in the southern end. The dominant direction of the maximum principal tectonic stress is NE‐NEE, in agreement with the orientation of the tectonic stress field and that from focal mechanism solutions in adjacent areas from previous work. The current stress state of Singapore has a close relationship with convergence of the India, Australia, Philippine and Eurasia plates. According to Coulomb friction criteria, and taking the friction coefficient as 0.6~1.0, the possibility of sliding on the faults in Singapore has been analyzed in this work.