Pitfalls of Overconservatism in Geotechnical Engineering

by Ralph B. Peck, (Hon.M.ASCE), Consulting Engr.; Albuquerque, N.M.,

Serial Information: Civil Engineering—ASCE, 1977, Vol. 47, Issue 2, Pg. 62-66

Document Type: Feature article


The article cites at least three reasons why geotechnical engineers may be overconservative: (1) They may try to satisfy unreasonable standards established by themselves or others; (2) because predictions contain elements of uncertainty, they may compensate for uncertainties by conservative assumptions that accumulate to a highly conservative result; and (3) the interplay of legal, contractual, and insurance practices may influence their decisions. Examples through case histories are given in the settlements of nuclear power plants, tracking radar systems, underpinning for subways, and the seismic stability of arctic pipelines. The article also stresses the danger involved in putting the U.S. at economic disadvantage with the rest of the world because of overconservatism. It is recommended that geotechnical engineers take more care to ascertain the real properties of soil and rock, particularly with respect to compressibility and shear strength, encourage engineers to be more realistic about tolerable settlements, and resist compounding conservatism and start educating engineers and others of the pitfalls of overconservatism in order to advance the welfare of the public and the stature of the profession.

Subject Headings: Geotechnical engineering | Soil settlement | Uncertainty principles | Case studies | Power plants | Rock properties | Soil compression | Soil strength | Arctic

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