Environmental Engineering Reference
In-Depth Information
Table 5.10.
Deficiencies in logging of boreholes, test trenches and pits.
Problem
Consequences
Remedy
Logging rock in soil description terms, e.g. “black
Contractual claims relating to difficulty of excavation;
Use correct drilling techniques and/or log
silty clay” in holes drilled by auger, with the rock
incorrect design assumptions
correctly and/or log in soil and rock terms
ground to soil consistency by the drilling bit
Logging joints, partings and drill breaks all
Incorrect assessment of the joint spacing leading to
Log joints, bedding plane partings and drill
together as “fractures”
incorrect assessment of ease of rippability and size of
breaks separately and present data clearly
ripped rock and contractual claims; incorrect assessment
of slope stability and grouting conditions
Failure to log condition of joints, e.g. clay coating,
Incorrect assessment of joint strengths in slope stability,
Use experienced personnel to log core (or
iron stained, and continuity of points.
and of likely flow rates of water, grouting conditions,
at least check logging). Define weathering
Poor definition of weathering classification
rippability. Confusion on acceptable rock conditions
classification and/or define acceptable
during construction with resultant contractual claims
conditions accurately
Incorrect description of cemented soils, either
Incorrect assessment of conditions for design and
Inspect exposures in large cuttings, dig
failing to describe the cementing, e.g. in calcareous
contractual claims for excavation or tunnel support
pits, relate drilling results to the local
sands OR describing cemented soil as rock
conditions
geology and log accordingly
Failure to log soil structure, e.g. fissures,
Incorrect assessment of shear strength of fissured soils,
Log carefully and systematically in pits
root holes, minor interbedding
underestimation of permeability
Classifying soils in the dry state
Underestimation of clay content and plasticity leading to
Moisten soil before classifying
incorrect design specification and contractual claims
Incomplete description of soil, e.g. omission of
Incorrect assessment of conditions for design, specification
Log carefully and systematically
moisture conditions, consistency, colour
and contractual claims based on unforeseen “wet soil” etc.
Inadequate description of “organic matter”
Contractual claims and incorrect design
Describe in detail in the logs
and “fill”
Copyright © 2005 Taylor & Francis Group plc, London, UK
