Good quality geotechnical investigations is very crucial to
the success of every construction project. A proper geotechnical
investigation will identify underground and soil conditions
and will determine the proper geotechnical design parameters.
Unfortunatelly, many projects lack a proper geotechnical investigation.
As a result, engineers are all too often forced to use overconservative
design parameters. In a worst case scenario, an inadequate geotechnical
investigation will not properly identify soil conditions and
will result in "unexpected" delays, failures, and
added construction costs.
A good quality geotechnical investigation identifies:
a) Soil layers and types, bedrock elevations if possible
b) Soil density and strength, as well as other mechanical soil
properties
c) Ground water conditions
d) Obstructions and existing underground structures
A soil ivestigation may include the following items:
| 1. Reconnaisance |
2. Exploration |
3. Field Tests |
| Visual inspection |
Geophysical |
Penetration tests |
| Airphotos |
Electrical |
Vane tests |
| Geologic reports and maps |
Pits - sampling and testing |
Water table - pore pressure tests |
| Records of past construction |
Borings - sampling and testing |
Pumping tests |
| |
|
Load tests |
| |
|
Compaction tests |
The above geotechnical data are then assessed for risks posed
by site condition and used in designing earthworks, structure
foundations. A proper geotechnical investigation will also aid
in properly indentifying critical points to monitor during earthwork
and foundation construction.
Geotechnical site investigations are almost always needed in
major projects and help gain an understanding of the project area.
Soil and rock samples are typically collected with a dril rig
and appropriate samplers. The soil samples are then transported
to a geotechnical laboratory where a number of geotechnical tests
are carried out. In situ tests typically include the Standard
Penetration Test and the Cone Penetrometer Test.
The Standard Penetration Test is one of the oldest geotechnical
field tests. It is an in-situ dynamic penetration test designed
to provide information on the geotechnical engineering properties
of soil. It involves the insertion of a standard sampler within
a borehole. The rods are hammered with a standard 140lb weight
that drops a distance of 30 inches. The number of blows required
for driving the sampler through three 6-inch intervals is recorded.
The sum of the blows over the last two 6-inch intervals is referred
as the Standard Penetration Number.
Deep Excavation LLC provides competitive geotechnical investigation
services for any sized project. We are licensed in the US and
in Europe. Through our associate network we can extend our services
all arround the world to meet your needs.
