3 Terms and definitions

For the purposes of this document, the terms and definitions given in EN 1997-1, EN 1997-2, ISO 14688-1 and ISO 14689-1 and the following apply.

NOTE Additional terms and definitions can be found in the books and literature listed in the Bibliography.

3.1 Site investigation methods

3.1.1

trial pit

open excavation constructed to examine the ground conditions in situ, recover samples or carry out field testing

3.1.2

shaft

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

3.1.3

heading adit

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

3.1.4

borehole

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.

3.1.5

drilling

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

3.1.6

small diameter drilling

drilling in the soil with a diameter greater than 30 mm but less than 80 mm

3.1.7

drilling method

technique employed to create and stabilise the borehole

3.2 Drilling rigs and equipment

3.2.1

drilling tool

device attached to, or forming an integral part of, the drill string, used as a cutting tool for penetrating the geological formation

3.2.2

drill bit

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

3.2.3

drill rig

device which carries out the drilling function

3.2.4

casing

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

3.2.5

flushing medium

liquid or gaseous medium used to move cuttings and/or samples and to lubricateand cool the drilling tool from the borehole

3.2.6

flushing additive

substance added to the flushing medium in order to affect or change its properties to improve its functioning

3.2.7

core lifter

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

3.2.8

sample retainer

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

3.3 Sampling

3.3.1

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.

3.3.2

sampling by using sampler

process by which samples are obtained by samplers from trial pits, headings, shafts or borehole bottom at selected positions

3.3.3

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

3.3.4

sample

defined amount of rock, soil or groundwater recovered from recorded depth

3.3.5

core, core sample

cylindrical sample of soil or rock obtained from a borehole fromrecorded depth

3.3.6

block sample

sample of soil or rock cut out by special techniques

3.3.7

cuttings

particles of geological formations formed in the borehole by the cutting action of the drilling tool

3.3.8

suspended matter

abraded ground material in the flushing medium generated by drilling, in which the individual particle size cannot be recognised with the naked eye

3.3.9

core run

length of the core drilling between the start and the finish for the removal of the sample

3.3.10

core loss

difference between a core run and the length of the core recovered

3.3.11

area ratio

C_a ratio of the area of soil displaced by the sampler tube in proportion to the area of the sample

Area ratio

See Figure 1.

NOTE 1 The area ratio is expressed in percent.

NOTE 2 One of the factors that determinesthe mechanical disturbance ofthe soil.

3.3.12

inside clearance ratio

C_i

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.

Definitions of the diameters cutting shoe

Key

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)

Figure 1 — Definitions of the diameters D₁, D₂, D₃ and D₄

3.3.13

outside clearance ratio

C_o

Outside clearance ratio

See Figure 1.

NOTE The outside clearance ratio is expressed in percent.

Fracture state terms

3.3.14.1

total core recovery in rock

TCR

total length of core sample recovered (solid and non-intact), expressed as a percentage of the length of the core run

See Figure 2.

3.3.14.2

rock quality designation

RQD

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.

3.3.14.3

solid core recovery

SCR

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.

$Application of fracture state terms for rock cores$

Key

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

Figure 2 — Application of fracture state terms for rock cores

3.3.15

sample recovery ratio in soil

ratio of the length of the sample, l_g, to the length of the sample run, H

See Figure 3.

3.3.16

net sample recovery ratio

ratio of the net length of the sample, l_n, to the length of the sample run, H

See Figure 3


a) Before withdrawal of sampler		b) After withdrawal of sampler

Key

1 casing
2 beginning of coring
3 end of coring
4 bottom of predrilled borehole
5 vent-hole
6 sample
D₃ inside diameter of the sample tube or liner
H length of the sample run
Z_f depth, under thenatural ground level, ofthe lower end of the sampler after sampling and beforewithdrawing the sampler
Z_i depth, under thenatural ground level, ofthe borehole bottom before sampling, and before the beginning of the following core run

l_b length of the lower part of the sample, which was remoulded or lost
l_e difference between the sample run and the actual length of the sample
l_g total length of the sample after withdrawal of the sampler, measured from the top of the sample to the cutter edge, including the remoulded or lost parts at both ends ofthe sample
l_h length of the remoulded or polluted upper part of the sample
l_n net length of the sample, before its conditioning
l_t effective(useful) length of the sampling tube

Figure 3 — Lengths of core run and sample

3.3.17

thin-walled sampler

soil sampler with a low area ratio and a low taper angle and thin edge

3.3.18

thick-walled sampler

soil sampler that has an area ratio, taper angle and/or edge larger than that of thin-walled sampler

3.4 Groundwater measurements

3.4.1

piezometric head

sum of pressure head and elevation

3.4.2

groundwater surface

upper boundary surface of the groundwater

3.4.3

aquifer

body of permeable rock or soil mass suitable for containing and transmitting groundwater

3.4.4 aquitard

confining layer that retards, but does not prevent, the flow of water to or froman adjacent aquifer

3.4.5

aquiclude

body of soil or rock with extremely low transmissivity, which effectively prevents the flow of water through the ground

3.4.6

confined aquifer

aquifer which is bounded above and below by aquicludes

3.4.7

unconfined aquifer

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

3.4.9

permeability

capacity of soil or rock for transmitting water

3.4.10

filter

water permeable section of a piezometer retaining the soil

3.4.11

filter pack

water permeable backfilling around the filter and retaining the soil

3.4.12

open filter area

opening percentage of the filter surface

3.4.13

groundwater measurement

measurement of the groundwater surface or pore pressure

3.4.14

groundwater measuring station

place where groundwater measuring equipment is installed or groundwater measurement is carried out

3.4.15

groundwater fluctuations

variations of groundwater surface and/or pore pressure

3.4.16

groundwater pressure

the pressure in pores, voids and fissures in the ground at a certain point and time

3.4.17

piezometer

equipment for the determination of the groundwater or the piezometric head, including both open and closed systems

3.4.18

open system

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

3.4.19

closed system

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

3.4.20

hydraulic system

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

3.4.21

pneumatic system

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

3.4.22

electrical system

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

3.4.23

pick-up system

electrical transducer system, in which the transducer can be added to and removedfrom the filter tip installed in the ground

3.4.24

filter tip

tip for piezometers provided with a filter to prevent soil particles from entering the equipment

3.4.25

high air entry filter

filter with small pores giving a high resistance to air entry when water saturated

3.4.26

time lag

time lapse between a change in pore pressure in the ground and its total recording by the measuring system