Testing in Constant Normal Stiffness (CNS) conditions have been widely used to better represent the effects of soil contraction/dilation on the normal stress at the interface between the soil and the piles. A new (2021) upgrade to the control system and the firmware of GDS’ Electromechanical Dynamic Cyclic Simple Shear Device (EMDCSS) allows the apparatus to perform both static and dynamic simple shear tests in CNS conditions.
The upgrade allows the customer to choose the value of the constant normal stiffness required for the test in kPa/mm or kN/mm. Systems purchased prior to 2021 can also be upgraded to perform CNS testing, it does not require any hardware modifications of the existing equipment and can be done remotely. Please contact GDS for more information. For more information on the EMDCSS click here.
Static simple shear results showing the difference between the constant normal load and constant normal stiffness conditions.
Results from the dynamic CNS simple shear tests with varying constant normal stiffness and horizontal strain amplitude.