SYMPOSIA PAPER Published: 01 January 1981
STP28773S

Residual Shear Strength Determination of Overconsolidated Nespelem Clay

Source

Peaking operations at Grand Coulee Powerplant, Washington, could result in future downstream river fluctuations of up to 12 m (38 ft) within a 24-h period and trigger dangerous landslides. Much of the riverbank consists of old landslide deposits in varved, overconsolidated clays and silts. The residual shear strength of the clay was determined from drained, repeated (reversing) direct shear tests on slickensided or precut sliding surfaces under three normal loads. Two displacement rates were initially used. The residual strength, measured after large cumulative displacements, was used in slope stability analyses. This paper describes problems encountered during testing, the test procedure adopted, the fully automated direct shear apparatus and data recording system, results to date, and planned future research. In one of the downstream riverbank areas, a residual shear strength range of 10 to 13 deg was confirmed by a back analysis of a recent slide.

Author Information

Miedema, D
Soil Mechanics Section, Geotechnical Branch, Water and Power Resources Service, Denver, Colo.
Byers, J
Soil Testing Section, Geotechnical Branch, Water and Power Resources Service, Denver, Colo.
McNearny, R
Soil Mechanics Section, Geotechnical Branch, Water and Power Resources Service, Denver, Colo.
Price: $25.00
Contact Sales
Related
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Details
Developed by Committee: D18
Pages: 594–609
DOI: 10.1520/STP28773S
ISBN-EB: 978-0-8031-4806-2
ISBN-13: 978-0-8031-0789-2