A study of the CBR Bearing Capacity Test for Hydrated Geosynthetic Clay Liners

Abstract

A modified version of the California Bearing Ratio (CBR) penetration test was used to investigate the bearing capacity of hydrated geosynthetic clay liners (GCLs). The bearing capacity of GCLs is a concern because, once hydrated, the soft bentonite may squeeze laterally under concentrated loads. A series of bearing capacity tests were performed to study the influence of GCL product type, surcharge pressure, displacement rate, mold diameter, and termination criterion on lateral bentonite squeezing. Test results show that adhesive-bonded GCLs have a somewhat greater tendency for bentonite squeezing than reinforced GCLs. The magnitude of surcharge pressure during hydration is an important variable for GCL bearing capacity testing. The rate of piston displacement has little influence on the bearing capacity of hydrated GCLs. Confining molds having a diameter ⩾ 235 mm are satisfactory for the measurement of GCL bearing capacity. A standard CBR mold with a diameter of 152 mm is not recommended. Termination criteria based on a specified force or a peak in the force-displacement relationship may be unreliable for some tests. A specified displacement termination criterion of 20 mm was found to be more appropriate for the GCL bearing capacity tests conducted in this investigation.