Trr No. 1462 Soils, Geology, And Foundations
The effects of specimen grouting and the stiffness range on reliable external MR Measurements were investigated using six synthetic specimens of known stiffnesse, ranging from that approximating a soft subgrade to that approximating stiff base material [from 20.7 MPa (3 ksi) to 552 MPa (80 ksi)]. For stiffness below about 345 MPa (50,000 psi). MR values determined by external measurements with grouted specimens are identical to the known values from torsional testing. However for the stiffer specimens. M,Z values of the grouted specimens are less than those from torsional testing, and the deviation increases with the increasing stiffness of the specimen. The secant static moduli determined by both loading and unloading curves closely matched the cyclic MR at the same strain rate (or loading frequency), proving the feasibility of using the static testin, scheme instead of the more expensive cyclic test. Finally the effect, of specimen grouting were investigated using compacted whgrade soils.