New Mexico Geological Society Annual Spring Meeting — Abstracts

The increasing occurrence of structural failure due to foundation conditions has prompted a number of geotechnical investigations in New Mexico. An important cause of some of these failures is collapsible soil. Collapsing soils generally consist of loose, open-structured, low density, dry, medium to fine-grained material that compacts appreciably when wetted. Applied loads can cause differential settlement which an lead to the total destruction of a structure. Damage to roads crossing collapsing soils that have been insufficiently prepared has also been reported in New Mexico.

Thorough geotechnical studies are both expensive and time-consuming. There is little agreement among workers as to which techniques best define collapsing soil. To define and delineate areas of collapsible soil the following series of field and laboratory techniques is suggested to predict soil stability: aerial photographic interpretation; grain size analyses; Atterberg Limits; moisture content; standard penetration tests and dry density. Other tests which may enhance the above techniques include SEM and x-ray diffraction analyses for soil structure and clay mineralogy. Finally, modified and double consolidation tests and direct shear strength tests on soil with natural water content and ina saturated condition complete the suggested suite of tests for predicting collapsible soils.

The choice and extent of preconstruction soil treatment such as wetting, compacting or grouting can be better determined knowing the soil properties determined with these techniques.