3 Terms and definitions
NOTE Additional terms and definitions can be found in the books and literature listed in the Bibliography.
3.1 Site investigation methods
open excavation constructed to examine the ground conditions in situ, recover samples or carry out field testing
open vertical or steeply inclined excavation, typically more than 5 m deep, constructed to examine the ground conditions in situ, recover samples or carry out field testing
small tunnel driven horizontally or with a slight inclination from a shaft or into sloping ground to examine the ground conditions in situ , recover samples and carry out field testing
hole of any predetermined diameter and length formed in any geological formation or man-made material by drilling
NOTE Investigations carried out in such a hole can be to recover rock, soil or water samples from a specified depth or to carry out in situ tests and measurements.
process by which a borehole is produced in any geological formation by rotary, rotary percussive, percussive or thrust methods and in any predetermined direction in relation to the drill rig
small diameter drilling
drilling in the soil with a diameter greater than 30 mm but less than 80 mm
technique employed to create and stabilise the borehole
3.2 Drilling rigs and equipment
device attached to, or forming an integral part of, the drill string, used as a cutting tool for penetrating the geological formation
device attached to, or forming an integral part of, the drill string, used as a cutting tool to penetrate the formation being drilled by the drilling method employed
device which carries out the drilling function
tubing temporarily or permanently inserted into a borehole
NOTE Casing is used, e.g. to stabilise the borehole, to prevent the loss of flushing medium to the surrounding formation, or to prevent cross flow between different groundwater horizons
liquid or gaseous medium used to move cuttings and/or samples and to lubricateand cool the drilling tool from the borehole
substance added to the flushing medium in order to affect or change its properties to improve its functioning
split, internally slotted or serrated conical spring steel ring, grooves, flexible spring fingers, hinged wedge- shaped fingers or hinged flaps mounted in a carrier ring, to retain the core sample whilst the corebarrel is being hoisted from the borehole
cylindrical retainer fitted with a split-ring core lifter; it is mounted at the lower end of the sampler tube and used to retain the sample in the tube as the sampler is being lifted from the ground
sampling by drilling continuous sampling
process by which samples are obtained by the drilling tools as the borehole proceeds
NOTE The drilling process is designed to obtain complete samples of the length of theborehole. The drilling tools are used as sampling tools.
sampling by using sampler
process by which samples are obtained by samplers from trial pits, headings, shafts or borehole bottom at selected positions
soil sampling by small diameter drilling
sampling by drilling in soils, using drilling tools with a diameter greater than 30 mm but less than 80 mm
defined amount of rock, soil or groundwater recovered from recorded depth
core, core sample
cylindrical sample of soil or rock obtained from a borehole fromrecorded depth
sample of soil or rock cut out by special techniques
particles of geological formations formed in the borehole by the cutting action of the drilling tool
abraded ground material in the flushing medium generated by drilling, in which the individual particle size cannot be recognised with the naked eye
length of the core drilling between the start and the finish for the removal of the sample
difference between a core run and the length of the core recovered
Ca ratio of the area of soil displaced by the sampler tube in proportion to the area of the sample
See Figure 1.
NOTE 1 The area ratio is expressed in percent.
NOTE 2 One of the factors that determinesthe mechanical disturbance ofthe soil.
inside clearance ratio
See Figure 1.
NOTE 1 The inside clearance ratio is expressed in percent.
NOTE 2 One of the factors that determines the mechanical disturbance of the sample caused by the friction on the inside wall of sample tube or of the liner.
D1 inside diameter ofthe cutting shoe α taper angle
D2 greatest outside diameter of the cutting shoe 1 sample tube
D3 inside diameter of the sample tube or liner 2 cutting shoe
D4 outside diameter ofthe sample tube 3 liner (optional)
outside clearance ratio
See Figure 1.
NOTE The outside clearance ratio is expressed in percent.
Fracture state terms
total core recovery in rock
total length of core sample recovered (solid and non-intact), expressed as a percentage of the length of the core run
See Figure 2.
rock quality designation
sum length of all core pieces with at least one full diameter that are 100 mm or longer between natural fractures, measured along the centre line of the core, expressed as a percentage of the length of the core run
See Figure 2.
solid core recovery
length of core recovered as solid cylinders, expressed as a percentage of the length of the core run See Figure 2.
NOTE Asolid core has a full diameter, uninterrupted by natural discontinuities, but not necessarily a full circumference, and is commonlymeasured along the core axis or other scan line.
NOTE All features shown are natural discontinuities unless stated otherwise.
1 drilling-induced fractures Description of fracture state of rock cores:
2 at least one full diameter RQD rock qualitydesignation
3 no single full diameter SCR solid core recovery
4 non-intact TCR total core recovery
5 no recovery
6 core run
sample recovery ratio in soil
ratio of the length of the sample, lg, to the length of the sample run, H
See Figure 3.
net sample recovery ratio
ratio of the net length of the sample, ln, to the length of the sample run, H
See Figure 3
|a) Before withdrawal of sampler||b) After withdrawal of sampler|
soil sampler with a low area ratio and a low taper angle and thin edge
soil sampler that has an area ratio, taper angle and/or edge larger than that of thin-walled sampler
3.4 Groundwater measurements
sum of pressure head and elevation
upper boundary surface of the groundwater
body of permeable rock or soil mass suitable for containing and transmitting groundwater
confining layer that retards, but does not prevent, the flow of water to or froman adjacent aquifer
body of soil or rock with extremely low transmissivity, which effectively prevents the flow of water through the ground
aquifer which is bounded above and below by aquicludes
aquifer in which the groundwater surface forms the upper boundary
3.4.8 pore pressure
pressure of the fluid that fills the voids of a soil or rock mass
capacity of soil or rock for transmitting water
water permeable section of a piezometer retaining the soil
water permeable backfilling around the filter and retaining the soil
open filter area
opening percentage of the filter surface
measurement of the groundwater surface or pore pressure
groundwater measuring station
place where groundwater measuring equipment is installed or groundwater measurement is carried out
variations of groundwater surface and/or pore pressure
the pressure in pores, voids and fissures in the ground at a certain point and time
equipment for the determination of the groundwater or the piezometric head, including both open and closed systems
measuring system in which the groundwater is in direct contact with the atmosphere and in which the groundwater surface at the filter level is measured
measuring system in which the groundwater is not in direct contact with the atmosphere and in which the pore pressure at the filter level is measured hydraulically, pneumatically or electrically
closed system in which the water pressure in the filter tip is transmitted to a measuring unit on or close to the ground surface through a liquid-filled pressure tube
closed system in which the water pressure acts on a membrane located behind the filter of the filter tip and which is balanced by gas pressure on the membrane's reverse side by a pressure tube from the ground surface
closed system in which the water pressure effects the membrane located behind the filter of the filter tip and where the water pressure is converted into an electrical signal
electrical transducer system, in which the transducer can be added to and removedfrom the filter tip installed in the ground
tip for piezometers provided with a filter to prevent soil particles from entering the equipment
high air entry filter
filter with small pores giving a high resistance to air entry when water saturated
time lapse between a change in pore pressure in the ground and its total recording by the measuring system