Determination of stress distribution on active fault by means of Casagrande method; an innovative approach

Abstract

The investigation deals with the stress distributions of undisturbed soil samples taken by preconsolidation press method from paleoseismological studies in the Gerede (Bolu) segment of the North Anatolian Fault System (NAPS), which is one of the most important intra-continental active transform faults in the world. Taking into consideration of the theoretical principal stress directions causing the faulting in the soil samples, consolidation experiments were carried out in different directions and the preconsolidation pressure values (PPV) of the samples were found by Casagrande method. Relations between the prime stress directions which are effective in the mechanism of fault formation and the values of PPV found by the Casagrande method were revealed. With all these calculations, the principal directions and magnitudes of the principal stresses causing faulting in the near-surface depths on the Gerede segment of the NAFS have been determined by a new method. The Gerede segment of the maximum principal stress (sigma 1) value at N 55.5 degrees W and N 60 degrees W was found 554.08 kPa and 327.54 kPa respectively. The maximum principal stress (sigma 1) direction of the fault was found to be N 55.5 degrees W and the angle value was 44.5 degrees.