Consolidation of Root-Penetrated Clays: A Case Study

by Michael W. O'Neill, (M.ASCE), Asst.Prof., Dept. of Civ. Engrg.; Univ. of Houston, Tex.,
Ronald Calsing, (A.M.ASCE), Geotechnical Engr.; Lockwood Greene, Inc., Spartanburg, S.C.,
B. Kent Merritt, (A.M.ASCE), Geotechnical Engr.; Southwestern Labs., Inc., Beaumont, Tex.,

Serial Information: Journal of the Geotechnical Engineering Division, 1976, Vol. 102, Issue 8, Pg. 857-873

Document Type: Journal Paper


The problem of predicting rates of settlement of clays penetrated by a network of tree roots was investigated by constructing two instrumented embankments within a common vegetative environment. The clays at the two sites had considerably different properties, but both were normally consolidated to slightly overconsolidated. Observations revealed that the tree roots act as efficient internal drains. Analytically, the roots were modeled as horizontally stacked drainage layers and as regularly spaced vertical drains in several rate prediction procedures. Drain characteristics were back-calculated based on observations at one fill and applied to the prediction of settlement rates of the other fill with generally good accuracy. This fact demonstrates that it is possible to predict the rate of settlement of a root-penetrated clay using existing computational methods properly modified to account for effective root spacing and diameter.

Subject Headings: Soil settlement | Consolidated soils | Case studies | Drainage | Vegetation | Clays | Trees | Soil properties

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