Experimental Study of the Mechanics of Gypsum Seam Hazard for Abu Dhabi

Abstract

Gypsum and rock salts behave plastically at comparatively low confining pressures and are soluble. When gypsum is exposed to groundwater flow, it may dissolve with the development of karst features. Continuous exposure to groundwater can further lead to subsidence or even collapse of the overlying ground surface. This is a major threat in underground construction over gypsiferous terrains, and thus understanding the phenomena is of paramount importance. In this work, an experimental study on the dissolution process of gypsum rock is performed using artificially created gypsum specimens, which are a representative of the in-situ gypsum rock specimens obtained from Abu Dhabi. The specimens are subjected to flow-through-tests. Changes of the original specimen with respect to its geometric and mechanical properties are investigated as well as the solute concentration content in the permeating water. Results obtained show that for an initially saturated gypsum specimen, there is a sharp decline in concentration with time (Stage I), followed by a constant concentration (Stage II) before a slight gradual increase is observed (Stage III) with time as per the RTRP model. However, beyond the RTRP model prediction, a gradual decrease in concentration is realized before a constant concentration is observed with time.

Date of Award	2015
Original language	American English
Supervisor	Rita Sousa (Supervisor)