The undrained elastic (small-strain) behavior of drilled shafts in cohesive soils is addressed herein. A database of load tests is evaluated using the L_1-L_2 method, in which L_1 is the elastic limit, defined at a specific load (Q_(L1)) and corresponding displacement (#rho#_(L1)). Values of undrained elastic soil modulus (E_u) are hack-calculated from Q_(L1) and #rho#_(L1) in the load tests and subsequently are normalized by the undrained shear strength (s_u), unit side resistance (f = #alpha#s_u)and cone tip resistance (q_c). All three normalized E_u ratios are similar in that the coefficient of variation (COV) values on their means range from 60 to 70 percent in uplift to about 80 to 90 percent in compression. These COVs are, in general, somewhat larger than those for #rho#_(L1). The results demonstrate that elastic behavior can be quantified using either normalized #rho#_(L1) or E_u values, but large COVs are inherent in subsequent displacement predictions.
展开▼
