core logging and evaluation

8/6/2019 Core Logging and Evaluation

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ROCK CORE EVALUATI

GEOTECHNICAL ENGINEERIN

GEM-23

GEOTECHNICAL ENGINEERIN

AUGUST 2006


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GEOTECHNICAL ENGINEERING MROCK CORE EVALUATION MA

GEM-23

STATE OF NEW YORKDEPARTMENT OF TRANSPORT

GEOTECHNICAL ENGINEERING B


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TABLE OF CONTENTS

I. INTRODUCTION .............................................................

II. BRIEF GLOSSARY OF GEOLOGIC TERMS ...............

III. ROCK CORE EVALUATION PROCEDURE................A. Recovery..........................................................................B. Rock Quality Designation (RQD) ...................................

C. Rock Type.......... .............................................................

1. Igneous...........................................................................

2. Metamorphic.... ..............................................................3. Sedimentary...... .............................................................

a. Compaction.... ..............................................................

b. Cementation..................................................................D. Color................................................................................

E. Mineralogy, Grain Size, and Texture ..............................

F. Bedding.............. .............................................................G. Fractures............. .............................................................

H. Size Range of Pieces .......................................................

I. Hardness........... ...............................................................

J. Weathering....... ...............................................................K. Additional Observations..................................................

L. Photographs...... ...............................................................

M. Rock Core Logs...............................................................

REFERENCES ..........................................................................

APPENDIX A Rock Core Evaluation Sheet............ ............

APPENDIX B Sample Rock Core Log................................


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LIST OF TABLES

Table 1: Igneous Rocks.............................................................

Table 2: Metamorphic Rocks....................................................Table 3: Sedimentary Rocks .....................................................

Table 4: Sedimentary Rock Bedding ........................................

Table 5: Fracture Density..........................................................Table 6: Fracture Healing..........................................................

Table 7: Rock Hardness ............................................................Table 8: Weathering Categories................................................


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I. INTRODUCTION

This manual presents a procedure for describing rock core sam

State Department of Transportation, by State work forces and

foundation, rockslope, and other engineering purposes. The ecomprehensive word description of the core samples to those

construction, and maintenance processes.

The procedure involves visual and manual examination of c

type, color, composition, bedding, structure, hardness aninformation will be used to generate an official Rock Core Logwill be made available to interested parties, including de

NYSDOT obtains large quantities of rock core samples but

advance the required geologic designs are evaluated and th

developed.

The standardized charts and tables herein, used as descriptive

are adopted from various organizations, such as the U.S. DSurvey, the American Institute of Professional Geologists (A

Navy, Naval Facilities Engineering Command, etc.). It shoul

final core descriptions and rock quality assessments are basedperforming the evaluation. Additional tests that may be per

and/or Unconfined Compressive Strength tests, are not in

descriptions but to provide further information that will be repo


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II. BRIEF GLOSSARY OF GEOLOG

Banding: Layering in the rock. The layers may be beddin

angle to bedding in sedimentary rock.

In metamorphic rock, the layering is called fol

the alignment of platy (flat) and/or elongatepressure of metamorphism. The foliations may

the original bedding. Sometimes the original only the foliations can be observed.

Igneous rocks normally do not exhibit bandi

settlement during hardening.

Bedding: The layers in sedimentary rock parallel to the o

original bedding planes were often, but not alwa

tend to break along bedding planes.

Cement: The material, usually chemically precipitated,

sedimentary rocks together (see grains and matr

Cleavage: Closely spaced parallel planes along which roc

a result of weakness along bedding planes in sed

or may be a secondary development by metamorphic rock (slaty cleavage). Slaty cleav

angle to original bedding.

Diagenesis: The process of chemical, physical and/or biolog

during its conversion into rock, exclusive of m

lithification).

Effervescence:The fizzing action that occurs when a carbCaCO3) is placed in contact with hydrochlor

Fault: A fracture in rock along which there has been

In rock cores, a fault can sometimes be recogniz

veins.


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Fracture: Breakage in rock. The fracture may be parall

bedding, cleavage, foliation or lamination. Ffracture.

Grains: The particles of which a rock or sediment is com

Joint: A fracture in rock along which there has be

fault).

Lamination: Very thin layering in rock, less than 0.4 inches of physical or chemical variations. Laminatioangle to bedding (cross-laminations) in sedimen

Lithification: The process by which loose sediment becomes r

Lithology: The character of a rock described in terms

composition, grain-size, and arrangement of its

Matrix: The fine-grained portion, not necessarily cem

(sandstone, conglomerate, etc.) in which the co

matrix may or may not be cemented (see cemen

Mineral: An inorganic substance, not necessarily of inor

chemical composition, or range of composi

properties and/or molecular structure. The basi

Sediment: Solid material, either mineral or organic, that h

origin, by air, water, ice or biological activity,earth's surface, above or below water.

Weathering: The process by which rocks are broken down external agencies such as wind, water (rain a

change, plants and bacteria.


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III. ROCK CORE EVALUATION PR

A proper description of rock obtained in drill cores is a valuabl

in determining the properties of bedrock with regard to roc

design.

When evaluating rock core, the Engineering Geologist should m

A. Recovery,B. RQD,

C. Rock type,D. Color,E. Mineralogy, Grain size & Texture,

F. Bedding,

G. Fractures,

H. Size range of core pieces,I. Hardness,

J. Weathering,

K. Additional observations,L. Photographs, and

M. Rock Core Log. The results are to be recorded on a R

Appendix A) and used to prepare an official Rock Core

A. RECOVERYThe recovery of each core run is usually determined by the D

Boring Log. Where the recovery is not made available, the En

the recovery (in percent) as the length of core recovered divirun, multiplied by 100. Areas where loss is likely to have oc

edges that don't match, zones of decay, etc.) should be noted.

B. RQDThe Rock Quality Designation (RQD) is a modified measure estimate the quality of the intact rock mass. The Engineerin

determination of RQD. The RQD (in percent) is obtained

recovered pieces of core equal to or greater than 4 inches (10 cthe core run, then multiplying by 100. In effect, the RQD idiscontinuities (bedding, fractures, faults, joints, shear zone

calculating RQD, it is important to try to distinguish between

and mechanical breaks which occur during coring procedi ti iti ill b id d h l l ti RQD W


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Note: RQD was originally developed for use with NX-size (

crystalline rock and used to describe rock quality for become virtually standard practice in drill core loggi

rock types. ASTM International indicates core sizes fr

(47.5 mm [3.35 in.]) are normally acceptable for meacores smaller than BQ, e.g., AX-size (30.2 mm [1.19 i

the true quality of the rock mass.

C. ROCK TYPE

Geologists divide rocks into three groups based on origin andgroups on the basis of composition and texture.

1. IGNEOUS ROCKSRocks formed from the solidification of molten m

rocks can be intrusive (solidifying below the su(solidifying at the surface from lava).

Intrusive igneous rocks are generally composed texture) while extrusive igneous rocks are

crystals/grains (finer texture).

In general, igneous rocks tend to have an interlocki

no appearance of layering, banding, or bedding.

2. METAMORPHIC ROCKS

Metamorphic rocks are Igneous and/or Sedimentmineral content have been changed by heat, p

solutions (invading gasses and/or liquids). In sohave been re-metamorphosed into other higher or lo

Metamorphic rocks can appear banded or layeretabular, or elongated mineral grains or the concen

distinct bands).

3. SEDIMENTARY ROCKSSedimentary rocks are formed by lithification of

transported and deposited by water, wind, ice, b

precipitation. In general, sedimentary rocks are comf i ti k


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Two important processes in the formation of

sediments are compaction and cementation.

a. Compaction is the physical process by whi

reduced by pressure. The weight of overlyingsediments, forcing out water and air and decrea

grains of sediment closer together. When mu

weak attractive forces may cause the grains to the loose sediment into rock. Claystone, mu

sedimentary rocks which may be formed in this

b. Cementation occurs as water circulates thro

elements in the water precipitate out and bind

Changes in the physical and/or chemical envir

Common cementing agents include silica co(calcite or aragonite, CaCO3). Various iron c

and Fe2O3) can also act as cements. The ceme

the pore spaces in the sediment. Rocks formedrange from very soft to very hard. Ceme

siltstone, sandstone and limestone are examples

cementation.

Note: For engineering purposes, rocks formed

compaction) are more durable than rocks formed by


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EB 06-039 Page 10 of 20

Table 1: Common Igneous R

IGNEOUS ROCKS

ROCK NAME COLOR GROUP TEXTURE MINERALS

PEGMATITEVery coarse

grained.

Quartz

Feldspar

Mica

Quartz and feldspar p

pink or green. Moder

GRANITECoarse to fine

interlocking grains.

Quartz

Feldspar

Mica

Hornblende

Pyroxene

White, gray or pink.

Feldspar is white, pin

SYENITE

Light colored

Coarse to fineinterlocking grains.

Feldspar

MicaHornblende

Pyroxene

Little or no quartz. FModerately difficult

DIORITECoarse to fine


FeldsparBiotite

Hornblende

Pyroxene

Often greenish in app

or gray. Moderately d

GABBROCoarse interlocking

grains.

Feldspar

Hornblende

Pyroxene

No quartz. Feldspar i

DIABASEMedium to fine


Feldspar

Hornblende

PyroxeneNo quartz. Commonl

BASALT

Dark colored

Fine interlocking

grains.

Feldspar

Hornblende

Pyroxene

No quartz. Feldspar i


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EB 06-039 Page 11 of 20

Table 2: Common Metamorphi

METAMORPHIC ROCKS

ROCK NAME COLOR STRUCTURE MINERALCOMPOSITION

QUARTZITE

White

Gray

Red

QuartzGlassy appearance. Ha

existing fracture planes

MARBLEWhite

Gray

Calcite

Dolomite

Often distinctly crystal

graphite. Effervesces in

SERPENTINITEYellowish

Green

Massive

Serpentine Soft. Can be easily scra

GNEISSGray

Green

Pink

BandedQuartz

Feldspar

Mica

Banded appearance du

difficult to drill.

SCHIST

Green

Gray

Brown

Foliated

(coarse-grained)

Mica

Quartz

Feldspar

Foliation due to alignm

SLATE/

PHYLLITE

Gray

Red

Green

Purple

Foliated

(fine-grained)

Mica

Quartz

Feldspar

Foliation due to alignm

usually shiny surface. M


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EB 06-039 Page 12 of 20

Table 3: Common Sedimentary

SEDIMENTARY ROCKS

ROCK NAME STRUC TUR E COLORPARTICLE

SHAPE

AND SIZE

PREDOMINANTMINERAL

COMPOSITION

CEMENMATRI

CONGLOMERATE

Red

Gray

Brown

Very coarse

to fine grains.Rock fragments.

Iron

Calcite

Silica

Clay

SANDSTONE

Red

Gray

Brown

Medium to

fine grains.

Rock fragments.

Quartz

Feldspar

Iron

Calcite

Silica

Clay

LIMESTONE

Light

Gray

To

Black

Angular to

rounded grains.Calcite

Calcite

Silica

Clay

DOLOSTONE

Massive or

layered.

White

To

Dark

Gray

Angular to

rounded grains.Dolomite

Calcite

Silica

Clay

SILTSTONE

MUDSTONE

SHALE

CLAYSTONE

Laminated

Red

Black

Gray

Green

Purple

Fine to very

fine particles.

Clay

Quartz

Feldspar

Clay

Calcite

Silica


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D. COLORThe color of the recovered rock is determined by comparing t

the Geological Society of America (GSA) Rock Color Chart.

important, are noted.

E. MINERALOGY, GRAIN SIZE, AND TEXTUREA description of the major minerals composing the rock. If p

grains/crystals and the texture of the rock (very fine to vdescriptions of mineralogy, grain size, and texture for the vari

rock type tables.

F. BEDDINGThe following table lists the categories of bedding used in desc

Table 4: Sedimentary Rock Bed

BEDDING DESCRIPT

Very Thick-Bedded Greater than 4 feet (> 12

Thick-Bedded 12 inches to 4 feet (30 cm

Medium-Bedded 4 inches to 12 inches (10

Thin-Bedded 1.2 inches to 4 inches (3

Very Thin-Bedded 0.5 inches to 1.2 inches

Thickly Laminated 0.1 inches to 0.5 inches (

Thinly Laminated Less than o.1 inches (< 0

None

For igneous and metamorphic rocks, any observable planar fea

be recorded using the same thickness designations as sediment


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G. FRACTURESThe spacing, orientation, filling, and degree of healing of t

determining the properties of the rock mass for structure found

The following tables list the fracture density (FD) and fracture

Table 5: Fracture Density

DEGREE OF

FRACTURING DESC

Unfractured No observed fractures.

Very slightly fractured Core recovered in lengths gr

Slightly to very slightly

fracturedCore recovered in lengths fr

Slightly fracturedCore recovered mostly in le1000 mm) with few scattere

mm) or greater than 3 feet (

Moderately to slightly fractured Core recovered mostly in le

Moderately fracturedCore recovered mostly in leto 300 mm) with most lengt

Intensely to moderatelyfractured

Core recovered mostly in le200 mm) with most lengths

Intensely fractured

Core recovered mostly in le

100 mm) with most lengths

with fragmented intervals.

Very intensely to intensely

fractured

Core recovered as short core

foot (30 mm).

Very intensely fracturedCore recovered mostly as ch

scattered short core lengths.


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Table 6: Fracture Healing

DEGREE OF

HEALINGDESCRIP

Totally HealedFracture is completely healed or re

hard as surrounding rock.

Moderately Healed

Greater than 50% of fracture mater

healed or re-cemented and/or strenhard than surrounding rock.

Partly HealedLess than 50% fracture material, fior re-cemented.

Not HealedFracture surface(s), fracture zone,

cemented.

H. SIZE RANGE OF CORE PIECESIndicate the range of size of pieces of core recovered in th

fragments too small to measure up to a single piece the enlocations of significant fragmented zones.


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I. HARDNESSThe following table lists the rock hardness categories:

Table 7: Rock Hardness

DESCRIPTION LONG DESC

Very soft rock Can be scratched with fingernail. Sligblow of point of geologic pick. Requir

Soft rock Hand-held specimen crumbles under fpick.

Moderately soft rock Shallow indentations (1 to 3 mm) canpoint of geologic pick. Can be peeled

difficulty.

Moderately hard rock Can't be peeled or scraped with knife.

a steel nail.

Hard rock Intact hand-held specimen requires m

break it. Can be faintly scratched by s

Very hard rock Cannot be scratched with a steel nail.

repeated, heavy blows with geologic h

Extremely hard rock Intact specimen can only be chipped,

blows of a geologic hammer.


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J. WEATHERINGThe following table lists the weathering categories:

Table 8: Weathering Categor

DEGREE OF WEATHERING DETAILED

Residual soilAdvanced state of decompoRock fabric and structure covolume change.

Completely weathered

Minerals decomposed to so

preserved (saprolite). Speci

penetrated.

Highly weathered

Most minerals somewhat de

broken by hand with effort opresent in rock mass. Textu

preserved.

Moderately weathered

Discoloration throughout. S

rock but cores cannot be broknife. Texture observed.

Slightly weathered Slight discoloration inwards

FreshNo visible sign of decompounder hammer impact.

K. ADDITIONAL OBSERVATIONS

Any observed properties of the core not covered in the previoulabeling discrepancies, marked difference in recovery calculevaluator, etc.).

L. PHOTOGRAPHSThe Geotechnical Engineering Bureau (GEB) Geologist


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M. ROCK CORE LOGSThe appropriate information from the Subsurface Exploration

Log Automation Program (BLAP) into the Rock Core databa

rock core evaluation (See Appendix A) are entered into the

Rock Core Logs are then produced (See Appendix B). Ifinformation is not available through BLAP, the official Rock C

The final Rock Core Logs, signed by the GEB's Engineering G

sent to the GEB's Highway Design & Construction (HD & C) s


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REFERENCES

American Institute of Professional Geologists (formerly

Geological Scientists), May 1977, Geologic Logging an

Engineering Purposes (Tentative).

ASTM International, Rev. 2002, Designation D6032 - 02, Stan

Rock Quality Designation (RQD) of Rock Core, 5 pp.

Chernicoff, S. and Whitney, D., 2007, Geology, An IntroduPearson Prentice Hall, 720 pp.

Deere, D. U. and Deere, D. W., "The Rock Quality Designatio

Classification Systems for Engineering Purposes, ASTM

American Society of Testing and Materials, Philadelphia, 1988

Hyndman, D. W., 1972, Petrology of Igneous and Metamorph

pp.

Leet, L. D., Judson, S. and Kauffman, M. E., 1978, Physical Ge

Englewood Cliffs, N. J., 490 pp.

New York State Department of Transportation, Geotechnical E

Manual, Working Draft, Section DM3.11, Subsurface Inve

Rock Samples.

New York State Department of Transportation, Geotechnica

1994, Soil Control Procedure STP-2, An Engineering DesProcedure, 9 pp.

Pettijohn, F. J., 1975, Sedimentary Rocks, Harper & Row Publ

Press, F. and Siever, R., 1978, Earth, 2nd ed, W.H. Freeman and

Tarbuck, E. J. and Lutgens, F. K., 1987, The Earth, An IntroduMerrill Publishing Company, Columbus, Ohio, 590 pp.

Thrush, P. W., and the staff of the Bureau of Mines, comp. & i l d l t d t U S D t t f th I t i


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U. S. Department of the Navy, Naval Facilities EngineerinManual 7.1 (NAVFAC DM - 7.1), 364 pp.

Whitten, D. G. A., with Brooks, J. R. V., 1972, The Penguin

Books Ltd., Harmondsworth, Middlesex, England, 517 pp.


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APPENDIX


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ROCK CORE EVALUATION


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ROCK CORE EVALUATION

PSN ___________________________________

PIN ___________________________________

BIN ___________________________________

Project _________________________________

_______________________________________

Date Evaluated ____________________

Top of Rock _______________ (Depth) _______________ (Elevation

Top of Sound Rock _______________ (Depth) ______________ (Ele

Comments _______________________________________________

_________________________________________________________

_________________________________________________________

RUN #1 Run Length ______________ Depth R

RQD __________ (as measured) _________ %

Rock Type _______________________________________________

Color ___________________________________________________

Mineralogy, Grain Size, & Texture ____________________________

Bedding _________________________________________________

Fractures ________________________________________________

Size Range of Pieces _______________________________________

Hardness ________________________________________________

Weathering _______________________________________________

ROCK CORE EVALUATION SHEET


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ROCK CORE EVALUATION SHEET

PSN _________________ PIN ___________________________

RUN # __________ Run Length _____________ Depth Range:

RQD __________ (as measured) _________ % Photo

Rock Type _______________________________________________

Color ___________________________________________________


Bedding _________________________________________________

Fractures ________________________________________________


Hardness ________________________________________________

Weathering _______________________________________________

Additional Comments ______________________________________

_________________________________________________________

_________________________________________________________

RUN # __________ Run Length _____________ Depth Range:

RQD __________ (as measured) _________ % Photo

Rock Type _______________________________________________

Color ___________________________________________________


Bedding _________________________________________________

Fractures ________________________________________________


Hardness ________________________________________________


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