STP1129

    Construction of Diaphragm Wall at Wells Dam East Embankment

    Published: Jan 1992


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    Abstract

    A concrete diaphragm wall was constructed at the Wells Dam east embankment to cutoff seepage. Sinkholes were observed on the embankment crest in early 1990, more than 20 years after the construction of the embankment dam. After extensive investigations a diaphragm wall was adopted to positively cutoff seepage and to stop internal erosion.

    The wall was excavated in vertical panels with clam shell bucket through the embankment core and riverbed deposits overlying bedrock to a maximum depth of 70 m (230 ft). A total of 11,600 sq m (125,000 sq ft) of diaphragm wall was constructed. The success of the wall was evaluated based on core drilling, water tests, piezometer data and geophysical survey after the construction.

    This paper presents a brief description of the project and sinkhole investigations, with the main emphasis placed on the construction of the concrete diaphragm wall, including procedure, quality control and verification, and difficulties.

    Keywords:

    Embankment dam, sinkhole, internal erosion, concrete diaphragm wall, geophysical, investigation


    Author Information:

    Roberts, DL
    Supervising Geologist and Senior Soils Engineer, Bechtel Corp., San Francisco, Ca.

    Ho, D-M
    Supervising Geologist and Senior Soils Engineer, Bechtel Corp., San Francisco, Ca.


    Paper ID: STP19737S

    Committee/Subcommittee: D18.20

    DOI: 10.1520/STP19737S


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