Dynamic strength of soil under multi-direction loading

A series of multi-directional loading tests on the two sands with changing phase and amplitude have been conducted by means of dynamic torsional hollow cylinder apparatus, which can apply vertical dynamic loading and horizontal dynamic torsional loading. The results of the test show that the dynamic strengths of sands under multidirectional loading condition are much lower than those under single directional loading. In the range of equivalent damage vibration number, Nf is from 10 to 30. The dynamic strength decreases 15% with the phase difference being 90° and dynamic strength decreases more than 30% with the phases being the same. For the design of geotechnical engineering during earthquake with multi-direction, 80-85 per cent of dynamic strength obtained from conventional single direction dynamic test can be used.