Drilling and Sampling of Soil and Rock

Purpose

Drilling and sampling of soil and rock for analysis and deciding on foundation type, depth and strength is a standard procedure for any large infrastructure project, may it be road and bridge construction, harbour jetty construction or very high rise building designing.

The design of building foundations, roadways, excavation, fills and slopes requires an understanding of soil strength; soil characteristics and consideration of problem soils and how soil behaves under imposed loads. Drilling and core samples provide the necessary samples for laboratory soil and rock tests and for on site field-testing. It is important to follow the criteria and guidelines so the appropriate drilling methods are selected especially since subsurface exploration is expensive but not nearly as expensive as for a project failure.

Course is designed and conducted as per contents of US Dept of Transportation FHWA Publication No. FHWA NHI-01-031 “Subsurface Investigation-Geotechnical Site Characterization” – Chapter 2 & 3.

Target Audience 

This course is intended for civil engineers and project engineers. The course will be of direct relevance to geologists, environmental scientists and civil engineers with little or no practical site experience. 

Course Content

Field Equipment for Drilling on Land and Water

Rig Type                                    Application

Truck-mounted drill rigs             Areas with easy access
All-terrain vehicles drill rigs       Sites with soft ground and rugged terrain
Track-mounted drill rigs            Sites with swampy and very soft ground
Skid drill rigs                             Sites with steep terrain
Wireline drill rigs                       Rock sampling
Hydraulic direct-push rigs         Fast, continuous sampling, cleaner (no spoils)
Sonic rigs                                 Continuous sampling of soil and rock

Barges – regular                      Over water drilling for shallow water depths (10 ft or less)
Jack up platform barges          Over water drilling for areas with deep water (up to 40 ft)

Borehole Advancement Methods

Manual methods & Test Pits

Rotary drilling
   – Hydraulic push
   – Percussive
   – Sonic drilling
   – Rotary wash
Auger drilling
   – Solid-Flight Augers
   – Hollow-Stem Augers

Soil Sampling

Split-Spoon (Disturbed Samples)

Direct-Push Sampling (Disturbed Samples)
   – Shelby Tube Thin wall Open Sampler
   – Laval Sampler
   – Piston Samplers
   – Rotary Core Sampling

Thin-Wall Tube Sampling (Undisturbed Samples)
   – Continuous Hydraulic Push Samplers
   – Continuous Sonic Samplers
   – Vibracore Samplers

Rock Coring Methods

   – Core Barrel Types
   – Logging Rock Core
   – Sample Protection

Boring Closure

Learning Outcome:

• Understand the guidelines for planning subsurface explorations for drilling and sampling of soil and rock
• Be aware of the minimum requirements for boring depths and frequencies required for various types of construction.
• Be familiar with the subgrade conditions that determine whether to select soil boring or rock drilling equipment.
• Understand the selection and assignment of appropriate drilling and sampling methods for a project as determined by  type of construction.
• Understand the advantages and limitations of various drilling methods and the most suitable use of drilling equipment for the soil formations and groundwater conditions that are countered.
• Be familiar with usage of drilling fluid, the types of soil formations and the groundwater conditions requiring drilling fluids.
• Understand the basic operation and parameters of boring and sampling equipment.
• Understand how undisturbed samples are obtained and when specialized procedures are required.
• Understand the importance of visual observations and available information gathered during drilling operations and procedures for recording on boring logs.