Laboratory Simulation of Irrigation-Induced Settlement of Collapsible Desert Soils Under Constant Surcharge

Abstract

The heterogeneous nature of soil as a load bearing material, coupled with varying environmental conditions, pose challenges to geotechnical engineers in their quest to characterize and understand ground behavior for safe design of structures. Standard procedures for checking bearing capacity and settlement alone may sometimes be insufficient to achieve an acceptable degree of durability and in-service performance of a structure, particularly under varying environmental conditions, whether natural or manmade. There exists a wide variety of problematic soils that exhibit swelling, shrinkage, dispersion and collapse characteristics occasioned by changes in moisture content. Specific examples are collapsible soils, which occur mainly in arid and semi-arid regions, are generally capable of resisting fairly large loads in the dry condition but suffer instability and significant strength loss when in contact with water. A number of case studies in the United Arab Emirates were examined, where lightly loaded structures such as boundary walls, pavements and footpaths had been built on ground overlying collapsible soil strata. Sustained irrigation of the dry landscapes was found to have caused uneven settlement of the collapsible soils leading to continuous distress to the structures as evident from cracking and deformation. To help address the problem, an opportunity has been taken to develop a laboratory method of simulating the loaded behavior of collapsible soils in varying situations and to measure its deformation at constant surcharge and ground water infiltration rates. Finally, relationships were developed to estimate the time and magnitude of settlement, if thickness of collapsible soil is known.

Three dimensional finite element analyses of ground settlement and structural damage caused by irrigation of desert landscapes overlying collapsible soil strata

“…Some researchers (Reznik 1993;Houston et al 1995;Mahmoud et al 1995) have attempted to characterize collapsible soils based on field tests, which are generally more expensive than laboratory tests but better representative of in-situ conditions. Other researchers (Holtz and Hilf 1961;Jennings and Knight 1975;Jasmer and Ore 1987;Lawton et al 1992;Anderson and Riemer 1995;Celestino et al 2000;Reznik 2007;Gaaver 2012;Kalantari 2013;Rezaei et al 2012;Vandanapu et al 2017) have gone a step further to develop laboratory tests to simulate the effects of water on a collapsible layer and to formulate settlement prediction equations. With recent advances in computing and technology, other researchers (Alonso et al 1990;Gens and Alonso 1992;Josa et al 1992, Wheeler andSivakumar 1995;Cui and Delage 1996;Wheeler 1996;Kato and Kawai 2000;Wheeler et al 2003;Sun et al 2007;Kakoli et al 2009;Sheng 2011;Arairo et al 2013;Rotisciani et al 2015) have applied numerical modeling to analyze the influence of collapsible soil settlement on structural foundations and superstructures.…”