Feasibility and Sensitivity Analysis of At-Rest Lateral Stress Coefficient (Ko) Evaluations Using Paired Shear Wave Velocity Modes

摘要

The lateral stress coefficient (Ko) is a fundamental geotechnical parameter that represents the anisotropic geostatic stress state. Aside from conventional field testing methods, this paper assesses in-situ K_o values using shear wave velocity (V_s) data from at least different two geophysical methods such as downhole test (DHT), standard crosshole test (CHT), and special CHT using a rotary hammer, vane source, or horizontal solenoid. The pairing of different sets of shear wave velocity modes including combinations of either V_(sHH) and V_(sHV) or V_(sHH) and V_(sVH) type (i.e., V_(Sij), where 'i' is the propagation direction and 'j' is the polarization direction) permits the evaluation of the lateral stress coefficient (Ko) using specific expressions. Based on well-documented data from nine international geotechnical experimentation sites, the feasibility of in-situ K_o assessment is investigated from regression analysis based on the modal V_s ratios such as V_(sHH)/V_(sVH) or V_(sHH)/V_(sHV).