Research on Wetting Collapsible Foundation Soils.

摘要

Irrigation of collapsible soils densifies them near ground surface. For underground pipelines, near-surface soils that have never been irrigated and are highly collapsible should be prewetted to cause soil collapse. The wetted stabilized pad supports the pipe and resists further subsoil collapse beneath and adjacent to the pad. The Bureau criteria for liquid limit natural dry density establishes the degree of looseness or collapsibility of the subsoils. Wetting tests were conducted on lateral 7R to determine minimal preconstruction foundation treatment for structures on collapsible soils. Fifteen test sections of 5.6-km total length were installed to compare surface flooding and sprinkling methods, with and without infiltration wells. A total of 9 m of applied irrigation water, usually hydrocompacted the upper 15 m of soil adequately for supporting pipelines and small pumping plants. Seepage and settlement rates and the time required for wetting subsoils to depths of 15 m are given. Ponding or sprinkling subsoils without wells saved water, but took 60 to 90 days to reach a 15-m depth where impervious layers did not prevent infiltration.