Good quality geotechnical investigations are 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. Unfortunately, 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 investigation may include the following items:
1. Reconnaissance | 2. Exploration | 3. Field Tests |
Visual inspection | Geophysical | Penetration tests |
Airphotos | Electrical | Vane tests |
Airphotos | 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 identifying 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 engineering 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.
Please contact us for more information
Solutions for Geotechnical Engineering Professionals:
DeepEX: Deep Excavations Design Software
DeepFND: Pile Foundations Design Software
HelixPile Helical Piles Design Software
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