CHAPTER 2.
FIELD EXPLORATION, TESTING, AND INSTRUMENTATION
Section 1.
INTRODUCTION
1. SCOPE. This chapter contains information on exploration methods
including use of air photos and remote sensing, geophysical methods, test
pits, test borings, and penetrometers. Also presented is information on
methods of sampling, measuring in situ properties of soil and rock, field
measurements, and geotechnical monitoring equipment.
2. RELATED CRITERIA. For other criterial related to exploration and
sampling, see the following sources:
Subject
Sources
Soil Exploration and Subgrade Testing.....................NAVFAC DM-5.04
Field Pumping Tests.......................................NAVFAC P-418
3. PLANNING FOR FIELD INVESTIGATIONS. The initial phase of field
investigations should consist of detailed review of geological conditions at
the site and in its general environs. This should include a desk top study
of available data including remote sensing imagery, aerial photography, and
a field reconnaissance. The information obtained should be used as a guide
in planning the exploration.
To the extent possible, borings should be supplemented by lower cost
exploration techniques such as test pits, probes, seismic refraction
surveys, and electrical resistivity surveys. This is particularly true in
the offshore environment where borings are exceptionally expensive.
Information on boring layout is given in Section 5 and a sample boring log
is given in Figure 1. Guidance on exploration techniques is given in
Sections 5 and 6.
It should be noted that NAVFAC has a Geotechnical Data Retrieval System.
To optimize its use, the U.S. Navy encourages utilization of its format on
Navy projects. Details relative to this can be found in Reference 1,
Geotechnical Data Retrieval System, by NAVFAC.
4. EXPLORATION PHASES. Project exploration can generally have three
phases: reconnaissance/feasibility exploration; preliminary exploration;
and detailed/final exploration. Additional exploration may be required
during or after construction. Frequently, all preconstruction phases are
combined into a single exploration effort.
a. Reconnaissance/Feasibility. Reconnaissance includes a review of
available topographic and geologic information, aerial photographs, data
from previous investigations, and site examination. Geophysical methods are
applicable in special cases. Reconnaissance/feasibility frequently reveals
difficulties which may be expected in later exploration phases and assists
in determining the type, number and locations of borings required.
7.1-49
Change 1, September 1986
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