Attachment 2 - FLH Rock Characterization Guide_2017 December FINAL.pdf

Federal Lands Highway

Rock Characterization Guidelines

Drilling BPA RFQ # 69056720Q000012 Attachment 02

CONTENTS

SECTION 1 – INTRODUCTION

1.1 REFERENCED PROCEDURES

SECTION 2 – INTACT ROCK PROPERTIES

2.1 ROCK TYPE

2.2 IGNEOUS ROCKS

2.3 SEDIMENTARY ROCKS

2.4 METAMORPHIC ROCKS

2.5 ROCK COLOR

2.6 GRAIN/CRYSTAL SIZE AND SHAPE

2.7 DEGREE OF WEATHERING

2.8 RELATIVE ROCK STRENGTH

SECTION 3 – DISCONTINUITY PROPERTIES

3.1 DISCONTINUITY SPACING

3.2 DISCONTINUITY CONDITION

3.3 RANGE OF MAJOR DISCONTINUITY ORIENTATIONS

3.4 ROCK CORE RECOVERY

3.5 ROCK QUALITY DESIGNATION

3.6 FRACTURE FREQUENCY

3.7 ROCK CORING TIME

SECTION 4 – OTHER PROPERTIES

4.1 SLAKING

4.2 VOIDS

4.3 LOSS OF CIRCULATION

SECTION 5 – REFERENCES

WY NPS YELL 10(24)

RFQ # 69056720Q000018 Attachment 10

SECTION 1 – INTRODUCTION

1.1 REFERENCED PROCEDURES

Rock characterization for engineering purposes consists of two basic assessments identified in the 1978 and 1981 International Society of Rock Mechanics (ISRM) publications; one based on the intact rock properties of the rock, and the other based on the discontinuity features. Together, the intact rock and the discontinuity properties define the overall rock mass.

• Intact rock properties - This assessment is based on the character of the intact rock (hand specimens and rock core) in terms of its genetic origin, mineralogical make-up, texture, strength, and degree of chemical alteration and/or physical weathering.

• Discontinuity properties - This assessment is based on the engineering characteristics (orientation, spacing, etc.) of the bounding discontinuities (bedding, joints, foliation planes, shear zones, faults, etc.) within the rock mass.

Both assessments are essential to engineering characterization of the rock mass, and are the basis for rock slope design and excavation, tunnel design and excavation, foundation design on rock, rock anchorage, and characterization of rock quarries.

Several other rock mass classification systems for engineering purposes and standard guides for utilizing these other systems are presented in ASTM D5878 and STP 984, respectively. However, Federal Lands Highway (FLH) requires contractors and consultants to use the guidance presented in this document and the 1978 and 1981 ISRM publications unless otherwise directed.

Rock Characterization Order of Descriptors

The protocol for field logging the test hole is to first describe the intact rock properties followed by the description of the discontinuity properties within the rock mass.

INTACT ROCK PROPERTIES followed by DISCONTINUITY PROPERTIES

[Intact Rock Properties] ROCK TYPE (CAPS), degree of vesicularity (when applicable), rock color, grain size, weathered state, relative intact rock strength (grade). followed by [Discontinuity Properties] Discontinuity spacing, discontinuity condition, range of major discontinuity orientations, other properties (when applicable, e.g. voids, slaking, etc.)

Report the following information for each core run:

core recovery (CR), rock quality designation (RQD), fracture frequency (FF), rock coring time (RCT)

Some examples of this field logging protocol are as follows:

DIORITE, light gray, medium grained, slightly weathered, medium strong rock (R3).

Discontinuities are widely spaced and in fair condition, joints and fractures range from 15 to 35 degrees from assumed horizontal.

Run 1: CR = 100%, RQD = 80%, FF = 2, RCT = 15 minutes

BASALT, highly vesicular, dark gray, very fine grained, slightly weathered to fresh, strong rock (R4). Discontinuities are closely spaced and in poor condition, joints range from 70 to 80 degrees from assumed horizontal with a flow contact at 12 degrees from assumed horizontal.

Run 7: CR = 65%, RQD = 20%, FF = 20, RCT = 12 minutes

Run 8: CR = 75%, RQD = 10%, FF = 10, RCT = 10 minutes

SILTSTONE, dark gray, very fine grained, slightly weathered, very weak rock (R1).

Discontinuities are widely spaced and in fair condition, apparent bedding ranges from 32 to 46 degrees from assumed horizontal, apparent potential for slaking.

Run 4: CR = 100%, RQD = 100%, FF = 1, RCT = 6 minutes

Silty SAND, very dense, moist, coarse, subangular sand, homogeneous, no HCl reaction, residual SANDSTONE. Residual SANDSTONE is light gray, residual soil to completely weathered, extremely weak rock (R0).

SECTION 2 – INTACT ROCK PROPERTIES

2.1 ROCK TYPE

Rocks are divided into three general categories based on origin. These categories are igneous rocks, sedimentary rocks, and metamorphic rocks. For assistance in general identification of rocks and minerals, the November 1991 Federal Highway Administration (FHWA) publication entitled, “Rock and Mineral Identification for Engineers” should be utilized.

2.2 IGNEOUS ROCKS

Igneous rocks are those rocks that have been formed by the solidification of molten or partially molten material. Typically, they are characterized based on mineralogy and genetic occurrence (intrusive or extrusive). Texture is the most conspicuous feature (key indicator) of genetic origin.

In general, coarser grained igneous rocks are intrusive, having been formed (solidified) before the molten material has reached the surface; while the finer grained igneous rocks are extrusive and have formed (solidified) after the molten material has reached the surface. Although this generality is true in most cases, it must be stressed that there is no clear line between the two.

Exhibit 2.2–A should be used only as an aid in determining the possible genetic origin (intrusive versus extrusive) of the igneous rock. For grain size determination and descriptors use Exhibit 2.6–A.

Exhibit 2.2–A COMMON IGNEOUS ROCKS

Intrusive (Coarser Grained)

Extrusive (Finer Grained)

Primary Minerals

Common Accessory Minerals

Granite Rhyolite Quartz K-feldspar

Plagioclase, Mica, Amphibole, and

Pyroxene.

Quartz Diorite Dacite Quartz Plagioclase

Hornblende, Pyroxene, and Mica.

Diorite Andesite Plagioclase Mica, Amphibole, and Pyroxene.

Gabbro Basalt Plagioclase Pyroxene Amphibole

A special, but common, class of igneous rock is pyroclastic rocks (See Exhibit 2.2–B). These rocks have been derived from volcanic material that has been explosively or aerially ejected from a volcanic vent. Many pyroclastic deposits are not lithified and should be classified as soils in accordance with FLH Soil Description and Identification Guidelines.

Exhibit 2.2–B PYROCLASTIC ROCKS

Rock Name Characteristics

Pyroclastic Breccia

Pyroclastic rock whose average grain size exceeds 2.5 inches (64 mm); angular pyroclasts predominate.

Agglomerate Pyroclastic rock whose average grain size exceeds 2.5 inches (64 mm); rounded pyroclasts predominate.

Lapilli Tuff Pyroclastic rock whose average grain size is 0.08 to 2.5 inches (2 to 64 mm).

Ash Tuff Pyroclastic rock whose average grain size is less than 0.08 inches (2 mm).

Some extrusive volcanic rocks contain small sub-rounded to rounded cavities (vesicles) formed by the expansion of gas or steam during the solidification process of the rock. The occurrences of these vesicles (when applicable) are to be reported using an estimate of the relative area that the vesicles occupy in relationship to the total area of the sample. The designation is outlined in Exhibit 2.2–C

Exhibit 2.2–C DEGREE OF VESICULARITY (WHEN APPLICABLE)

Designation Percentage of Total Sample (by volume)

Slightly Vesicular 5 to 10 Percent

Moderately Vesicular 10 to 25 Percent

Highly Vesicular 25 to 50 Percent

Scoriaceous Greater than 50 Percent

2.3 SEDIMENTARY ROCKS

Sedimentary rocks are formed by the deposition and lithification of sediments such as gravels, sands, silts, and clays; or by chemical precipitation from solutions (rock salt), or from secretion of organisms (limestones). As indicated above, sedimentary rocks are characterized based on whether they are derived from clastic sediments or non-clastic (chemical precipitates, or organisms) (Refer to Exhibit 2.3–A and 2.3–B). As listed in Exhibit 2.3–B, a dilute mixture of hydrochloric acid (HCl) can be used to determine if a rock type contains appreciable calcium carbonate. The reaction of a clean face of the rock sample with HCl can help define the sedimentary, non-clastic rock type when they are similar in appearance.

Exhibit 2.3–A CLASTIC SEDIMENTARY ROCKS

Rock Type Original Sediment Conglomerate Sand, Gravel, Cobbles, and Boulders

Sandstone Sand

Siltstone Silt

Claystone Clay

Shale Laminated Clay and Silt

Exhibit 2.3–B NON-CLASTIC SEDIMENTARY ROCKS

Rock Type Primary Mineral HCl Reaction

Limestone Calcite Strong - violent reaction with bubbles forming immediately

Dolomite/ Dolostone Dolomite Weak - Some reaction with bubbles forming slowly

Chert Quartz None - No visible reaction

2.4 METAMORPHIC ROCKS

Metamorphic rocks are those rocks that have been formed from pre-existing rocks when minerals in the rocks have been recrystallized to form new minerals in response to changes in temperature and/or pressure, and these rocks do not completely melt as igneous intrusive rocks do.

Metamorphic rocks are characterized based on two general categories; foliated and non-foliated metamorphic rocks. Foliated metamorphic rocks contain laminated structure resulting from the segregation of different minerals into layers parallel to schistosity. Non-foliated metamorphic rocks are generally recrystallized and equigranular (Refer to Exhibits 2.4–A and 2.4–B).

Exhibit 2.4–A FOLIATED METAMORPHIC ROCKS

Rock Type Texture Formed From Primary Minerals

Slate Platy, fine grained Shale, Claystone Quartz & Mica

Phyllite Platy, fine grained with silky sheen

Shale, Claystone, Fine grained pyroclastic Quartz & Mica

Schist Medium grained with irregular layers

Sedimentary and Igneous Rocks

Mica, Quartz, Feldspar, and Amphibole

Gneiss Layered, medium to coarse grained

Sedimentary and Igneous Rocks

Mica, Quartz, Feldspar, and Amphibole

Exhibit 2.4–B NON-FOLIATED METAMORPHIC ROCKS

Rock Type Texture Formed From Primary Minerals

Greenstone Crystalline Intermediate Volcanics & Mafic Igneous Mica, Hornblende, and Epidote

Marble Crystalline Limestone &Dolomite Calcite & Dolomite

Quartzite Crystalline Sandstone & Chert Quartz

Amphibolite Crystalline Mafic Igneous & Calcium-Iron Bearing Sediments Hornblende & Plagioclase

2.5 ROCK COLOR

Rock color is not in itself a specific engineering property, but may be an indicator of the influence of other significant geologic processes that may be occurring in the rock mass (e.g. fracture flow of water, weathering, alteration, etc.) Color may also aid in the subsurface correlation of rock units. The color of the rock should be based on the 1977 Rock Color Chart from the Geologic Society of London provided in Exhibit 2.5–A. Use the 2009 Geological Society of America Munsell Rock Color Charts when specified by the project geotechnical engineer or engineering geologist. Rock color should be determined as soon as the core has been recovered from the test hole and while the core sample is wet.

Exhibit 2.5–A ROCK COLOR (MODIFIED AFTER GEOLOGICAL SOCIETY OF

LONDON, 1977)

1st Descriptor 2nd Descriptor 3rd Descriptor Light Yellowish White Dark Buff Yellow

Orangish Buff Brownish Orange Pinkish Brown Reddish Pink Bluish Red Purplish Blue Orange Green Olive Purple Greenish Olive Greyish Grey Black

2.6 GRAIN/CRYSTAL SIZE AND SHAPE

Grain/crystal size is defined as the size of the particles or mineral crystals that make up the intact portion of the rock. The description of grain/crystal size should follow the criteria as set forth in Exhibit 2.6–A.

Exhibit 2.6–AGRAIN/CRYSTAL SIZE FOR ROCKS (MODIFIED AFTER

WENTWORTH, 1972)

Grain Size Description Criteria Less than 0.003 inches

(<0.075 mm) Very fine grained Cannot be distinguished by unaided eye. Few to no mineral grains are visible with a hand lens.

0.003 to 0.02 inches (0.075 to 0.425 mm) Fine grained

Few grain/crystal boundaries are visible; grains can be distinguished with difficulty by the unaided eye but can be somewhat distinguished by hand lens.

0.02 to 0.08 inches (0.425 to 2 mm) Medium grained

Most grain/crystal boundaries are visible; grains distinguishable by eye and with the aid of a hand lens.

0.08 to 0.2 inches (2 to 4.75 mm). Coarse grained

Grain/crystal boundaries are visible; grains distinguishable with the naked eye and hand lens.

Greater than 0.2 inches (>4.75 mm) Very coarse grained Grain/crystal boundaries are clearly visible;

grains are distinguishable with the naked eye.

WY NPS YELL 10(24)

For sedimentary rocks, the grain shape criteria set forth in Exhibit 2.6-B should be used.

Exhibit 2.6–B GRAIN SHAPE (FOR SEDIMENTARY ROCKS)

Description Characteristic

Angular Showing very little evidence of wear. Grain edges and corners are sharp. Secondary corners are numerous and sharp.

Subangular Showing definite effects of wear. Grain edges and corners are slightly rounded off. Secondary corners are slightly less numerous and slightly less sharp than in angular grains.

Subrounded Showing considerable wear. Grain edges and corners are rounded to smooth curves. Secondary corners are reduced greatly in number and highly rounded.

Rounded Showing extreme wear. Grain edges and corners are smoothed off the broad curves. Secondary corner are few in number and rounded.

Well-rounded Completely worn. Grain edges or corners are not present. No secondary edges or corners are present.

2.7 DEGREE OF WEATHERING

Weathering is the process of mechanical and/or chemical degradation of the rock mass through exposure to the elements (e.g. rain, wind, groundwater, ice, change in temperature, etc.). In general, the strength of the rock tends to decrease as the degree of weathering increases. In the earliest stages of weathering only discoloration and a slight change in texture occur. As the weathering of the rock advances, significant changes occur in the physical properties of the rock mass, until ultimately the rock is decomposed to soil.

The characterization of the degree of weathering of the rock mass is based on six weathering classes (See Exhibit 2.7–A developed by the International Society of Rock Mechanics (ISRM, 1978 & 1981)).

WY NPS YELL 10(24)

Exhibit 2.7–A DEGREE OF WEATHERING

Term Description Grade

Fresh No visible sign of rock material weathering; slight discoloration on major discontinuity surface is possible. I

Slightly Weathered

Discoloration indicates weathering of rock material and discontinuity surfaces. All rock material may be discolored by weathering and the external surface may be somewhat weaker than in its fresh condition.

II

Moderately Weathered

Less than half the rock material is decomposed and/or disintegrated to a soil. Fresh or discolored rock is present either as a discontinuous framework or as corestones. A minimum 2-inch (50

mm) diameter sample cannot be broken readily by hand across the rock fabric.

III

Highly Weathered

More than half of the rock is decomposed and/or disintegrated to soil. Fresh or discolored rock is present either as a discontinuous framework or as corestones. A minimum 2-inch (50 mm) diameter sample can be broken readily by hand across the rock fabric.

IV

Completely Weathered

All rock material is decomposed and/or disintegrated to soil. The original mass structure is still largely intact. Material can be granulated by hand. If rock is considered to be completely weathered, use FLH Soil Description and Identification Guidelines to describe the residual soil material.

V

Residual Soil

All rock material is converted to soil. The mass structure and material fabric are destroyed but the apparent structure remains intact. There may be a large change in volume, but the soil has not been significantly transported. Material can be easily broken-down by hand. If rock is considered to be residual soil, use FLH Soil Description and Identification Guidelines to describe the residual soil material.

VI

Alteration is the process that applies specifically to the changes in the chemical or mineral composition of the rock due to hydrothermal or metamorphic activities. Alteration may occur in zones or pockets and can be found at depths far below that of normal weathering. Alteration does not strictly infer that there is a degradation of the rock mass or an associated loss in strength.

Where there has been a degradation of the rock mass due to alteration, Exhibit 2.7-A may be used to describe the alteration by simply substituting the word "altered" for the word weathered for Grade II through Grade V.

2.8 RELATIVE ROCK STRENGTH

Rock strength is controlled by many factors including degree of induration, cementation, crystal bonding, degree of weathering or alteration, etc. Determination of relative rock strength can be

WY NPS YELL 10(24)

estimated by simple field tests, which can be refined, if required, through laboratory testing. The relative rock strength should be determined based on intact specimens based on the ISRM method outlined in Exhibit 2.8-A. Due to the potential for variable rock conditions multiple relative strength designations may be required for each core run.

Exhibit 2.8-A RELATIVE STRENGTH OF INTACT ROCK SPECIMENS (ISRM, 1978 & 1981)

G ra de

Description Field Identification

Approximate Uniaxial Compressive

Strength

R0 Extremely Weak Rock Specimen can be indented by thumbnail.

35 – 150 psi

(250-1,000 kPa)

R1 Very Weak Rock

Specimen crumbles under sharp blow with point of geological hammer, and can be peeled with a pocket knife.

150 - 725 psi

(35 – 5,000 kPa)

R2 Weak Rock

Shallow cuts or scrapes can be made in a specimen with a pocket knife. A firm blow with a geological hammer point creates shallow indents.

725 – 3,500 psi

(5,000 – 25,000 kPa)

R3 Medium Strong Rock

Specimen cannot be scraped or cut with a pocket knife. Specimen can be fractured with a single firm blow with a geologic hammer point.

3,500 – 7,250 psi

(25,000 to 50,000 kPa)

R4 Strong Rock Specimen requires more than one firm blow of the geologic hammer point to fracture.

7,250 – 14,500 psi

(50,000 – 100,000 kPa)

R5 Very Strong Rock

Specimen requires many firm blows from the hammer end of the geologic hammer to fracture.

14,500 – 36,250 psi

(100,000 – 250,000 kPa)

R6 Extremely Strong Rock

Specimen can only be chipped with firm blows from the hammer end of the geologic hammer.

>36,250 psi

(>250,000 kPa)

If soil infilling is observed within the discontinuities, the hole depth, thickness, and field soil identification characteristics should be noted. In addition, a qualitative thumb penetration test should be conducted and described per Exhibit 2.8–B. Areas of prominent soil infilling should be placed in a plastic bag and sealed for moisture content and additional laboratory testing. Any moisture sensitive rock should be preserved (at a minimum) by wrapping the core in clear plastic to retain the field moisture conditions (e.g. claystone, siltstone, coal, argillaceous rocks, etc.).

Note that protective measures; such as, bubble wrap, or removing and individually wrapping core and placing them in a padded bucket for shipping may be required to preserve cored materials for laboratory testing. Guidance to Standard Practices for Preserving and Transporting Rock Core Samples is provided in ASTM D5079.

Exhibit 2.8-B RELATIVE STRENGTH OF SOIL INFILLING (ISRM, 1978 & 1981)

Grade Description Field Identification

Approximate Uniaxial Compressive

Strength

S1 Very soft Easily penetrated several inches by fist <3.5psi

(<25 kPa)

S2 Soft Easily penetrated several inches by thumb

3.5 – 7 psi

(25 - 50 kPa)

S3 Firm Can be penetrated several inches by thumb with moderate effort

7 – 14.5 psi

(50 - 100 kPa)

S4 Stiff Readily indented by thumb but penetrated only with great effort

14.5 – 36 psi

(100 – 250 kPa)

S5 Very Stiff Readily indented by thumbnail 36 – 72.5 psi

(250 – 500 kPa)

S6 Hard Indented with difficulty by thumbnail >72 psi

(>500 kPa)

SECTION 3 – DISCONTINUITY PROPERTIES

The discontinuity properties of a rock mass are based on the engineering properties of the bounding structure within the rock mass. Structure refers to large-scale (megascopic) planar features which separate intact rock blocks, and impact the overall strength, permeability, and breakage characteristics of the rock mass. Common planar features within the rock mass include joints, fractures, bedding, and faults; collectively called discontinuities. These common planar features are defined as follows:

Joints/fractures- Joints/fractures are discontinuities within the rock mass along which there has been no identifiable displacement.

Bedding - Bedding is the regular layering in sedimentary rocks marking the boundaries of small to massive lithological units or beds.

Faults - Faults are fractures or brecciated zones within the rock mass along which there has been significant shear displacement of the sides relative to each other. The presence of gouge and/ or slickensides may be indicators of faulting.

When defining the discontinuity properties of these planar features within the rock mass, the recovered rock core from the borehole is examined, and the following information is recorded:

• Discontinuity Spacing

• Discontinuity Condition

• Core Recovery

• Rock Quality Designation (RQD)

• Fractures Frequency (FF)

• Rock Coring Time (RCT)

• Range of Major Discontinuity Orientations

• Voids

3.1 DISCONTINUITY SPACING

Discontinuity spacing is the distance between natural discontinuities as measured along the borehole. An evaluation of discontinuity spacing within each core run should be made, and reported on the field logs in conformance with the ISRM criteria set forth in Table 13. Mechanical breaks caused by drilling or handling should not be included in the discontinuity spacing evaluation, and should be identified on the core by marking an “X” across the mechanical breaks.

Exhibit 3.1–A DISCONTINUITY SPACING (INCLUDES JOINTS/FRACTURES, BEDDING, AND FAULTS)

Description Spacing of Discontinuity

Extremely Widely Spaced >20 feet (> 6 m)

Very Widely Spaced ~6 to 20 feet (2 to 6 m)

Widely Spaced ~2 to 6 feet (600 mm to 2 m)

Moderately Spaced ~8 inches to 2 feet (200 to 600 mm)

Closely Spaced ~2 to 8 inches (60 to 200 mm)

Very Closely Spaced ~3/4 to 2 inches (20 to 60 mm)

Extremely Closely Spaced <3/4 inches (<20 mm)

3.2 DISCONTINUITY CONDITION

The surface properties of discontinuities, in terms of roughness, separation/gouge thickness, and wall hardness, affect the shear strength of the discontinuity. An assessment of the discontinuities within each core run should be made, and reported on the field logs in conformance with the descriptions and conditions in Exhibit 3.2–A.

The discontinuity condition description in Exhibit 3.2–A contains three items: roughness, separation/infilling measurement, and discontinuity wall condition. The least favorable condition of these three descriptors should drive the selection of the discontinuity condition. For example, the condition of the discontinuity is very rough, the separation is greater than ~0.04 inches (1 mm), and has a hard discontinuity wall, so it would be characterized as in “Fair Condition” because the separation is the least favorable condition.

Exhibit 3.2–A DISCONTINUITY CONDITION (ISRM, 1978 & 1981)

Condition Description Excellent Condition Very rough surfaces, no separation, hard discontinuity wall (>R2).

Good Condition Slightly rough surfaces, separation less than ~0.04 inches (1 mm), hard discontinuity wall (>R2).

Fair Condition Slightly rough surface, separation greater than ~0.04 inches (1 mm), soft discontinuity wall (<R3).

Poor Condition Slickensided surfaces, or soft gouge less than ~0.2 inches (5 mm) thick, or open discontinuities between ~0.04 and 0.2 inches (1 to 5 mm).

Very Poor Condition

Soft gouge greater than ~0.2 inches (5 mm), or open discontinuities greater than ~0.2 inches (5 mm).

WY NPS YELL 10(24)

For estimating discontinuity roughness, use the roughness profiles in Exhibit 3.2–B to estimate the Joint Roughness Coefficient (JRC) from ISRM, 1978 in Exhibit 3.2-A. Generally, very rough discontinuity surfaces have JRC’s greater than 10. To estimate discontinuity wall hardness, ISRM (1978 & 1981) suggests using the knife and geologic hammer rebound tests described in Exhibit 2.7-A for the relative strength of intact rock specimens.

Exhibit 3.2–B JRC RANGES (ISRM, 1978 & 1981)

3.3 RANGE OF MAJOR DISCONTINUITY ORIENTATIONS

Major discontinuities; such as, bedding, flow boundaries, disconformities, joints and fractures, etc.

should be noted in the logs. A goniometer, like the one shown in Exhibit 3.3-A, or a see-through compass should be used to measure the range of orientations of major discontinuities relative to an assumed horizontal plane.

WY NPS YELL 10(24)

Exhibit 3.3–A GONIOMETER

3.4 ROCK CORE RECOVERY

Core recovery (CR) is defined as the ratio of core recovered to the run length expressed as a percentage. Therefore:

𝑪𝑪𝑪𝑪 (%) = (𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻 𝑳𝑳𝑳𝑳𝑳𝑳𝑳𝑳𝑻𝑻𝑳𝑳 𝑻𝑻𝒐𝒐 𝑪𝑪𝑻𝑻𝑪𝑪𝑳𝑳 𝑪𝑪𝑳𝑳𝑹𝑹𝑻𝑻𝑹𝑹𝑳𝑳𝑪𝑪𝑳𝑳𝑹𝑹÷ 𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻 𝑳𝑳𝑳𝑳𝑳𝑳𝑳𝑳𝑻𝑻𝑳𝑳 𝑻𝑻𝒐𝒐 𝑪𝑪𝑻𝑻𝑪𝑪𝑳𝑳 𝑪𝑪𝑹𝑹𝑳𝑳𝑹𝑹𝑪𝑪𝑹𝑹𝑻𝑻𝑻𝑻𝑳𝑳𝑹𝑹)×𝟏𝟏𝟏𝟏𝟏𝟏

These values should be recorded on the field logs for each core run.

3.5 ROCK QUALITY DESIGNATION

The Rock Quality Designation (RQD) provides a subjective estimate of rock mass quality based on a modified core recovery percentage from a double or triple tube diamond core barrel. The RQD is defined as the percentage of “sound,” intact rock core recovered in pieces of 4 inches (100 mm) or more in length through the length of a core run. The soundness of a piece of rock core is qualitative and is typically a measure of the degree of weathering or hydrothermal weathering of the intact pieces. ASTM defines sound core as any core that is fresh to moderately weathered and has sufficient strength to resist hand breakage. Lengths should be measured along the centerline of the core piece and in accordance with ASTM D 6032. Therefore:

𝑪𝑪𝑹𝑹𝑹𝑹 (%) = �

𝑳𝑳𝑳𝑳𝑳𝑳𝑳𝑳𝑻𝑻𝑳𝑳 𝑻𝑻𝒐𝒐 𝑺𝑺𝑻𝑻𝑹𝑹𝑳𝑳𝑹𝑹 𝑪𝑪𝑻𝑻𝑪𝑪𝑳𝑳 𝑹𝑹𝑳𝑳 𝒑𝒑𝑹𝑹𝑳𝑳𝑹𝑹𝑳𝑳𝒑𝒑 > 𝟒𝟒 𝑹𝑹𝑳𝑳𝑹𝑹𝑳𝑳𝑳𝑳𝒑𝒑 (𝟏𝟏𝟏𝟏𝟏𝟏𝟏𝟏𝟏𝟏)

𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻 𝑳𝑳𝑳𝑳𝑳𝑳𝑳𝑳𝑻𝑻𝑳𝑳 𝑻𝑻𝒐𝒐 𝑪𝑪𝑻𝑻𝑪𝑪𝑳𝑳 𝑪𝑪𝑹𝑹𝑳𝑳 �×𝟏𝟏𝟏𝟏𝟏𝟏

Mechanical breaks caused by drilling or handling and lengths of core that are not “sound” should not be included in the RQD calculation. In addition, vertical fractures in the core should not be included in the RQD calculation. An example for measuring RQD is presented in Exhibit 3.5-A.

It provides the hole logger with a good example for measuring and calculating RQD.

Exhibit 3.5-A MEASURING RQD (DEERE, 1989)

3.6 FRACTURE FREQUENCY

Fracture frequency (FF) is defined as the number of natural fractures per unit length of core recovered. The fracture frequency is measured for each core run, and recorded on the field logs as fractures per foot (300 mm). Therefore, 𝑭𝑭𝑭𝑭 =

𝑵𝑵𝑹𝑹𝟏𝟏𝑵𝑵𝑳𝑳𝑪𝑪 𝑻𝑻𝒐𝒐 𝑳𝑳𝑻𝑻𝑻𝑻𝑹𝑹𝑪𝑪𝑻𝑻𝑻𝑻 𝒐𝒐𝑪𝑪𝑻𝑻𝑹𝑹𝑻𝑻𝑹𝑹𝑪𝑪𝑳𝑳𝒑𝒑

𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻𝑻 𝑻𝑻𝑳𝑳𝑳𝑳𝑳𝑳𝑻𝑻𝑳𝑳 𝑻𝑻𝒐𝒐 𝑹𝑹𝑻𝑻𝑪𝑪𝑳𝑳 𝑪𝑪𝑳𝑳𝑹𝑹𝑻𝑻𝑹𝑹𝑳𝑳𝑪𝑪𝑳𝑳𝑹𝑹 (𝒐𝒐𝑳𝑳𝑳𝑳𝑻𝑻)

Mechanical breaks caused by drilling or handling should not be included in the fracture frequency count. In addition, vertical fractures in the core should not be utilized in the fracture frequency determination. If there are significant changes in natural fracture patterns or a change in materials within a core run, two fracture frequencies should be reported for the differing characteristics of the rock.

WY NPS YELL 10(24)

3.7 ROCK CORING TIME

The time it takes to core a run of rock, known as the rock coring time (RCT), can provide valuable information to the designer and contractor regarding penetration rates of the rock units with the drilling methods being utilized. Time for each coring run should be indicated on the field logs.

Significant changes in penetration rate within a core run should be noted.

WY NPS YELL 10(24)

SECTION 4 – OTHER PROPERTIES

When applicable, use additional descriptors to describe specific geologic conditions encountered in the sample or non-soil material (i.e., slaking, voids, etc.). Guidelines for additional descriptors are provided in this Section. Do not include these additional descriptors unless they are relevant to the geology at the site.

4.1 SLAKING

Slaking is defined as the disintegration of a rock under conditions of wetting and drying, or when exposed to air. This behavior is related primarily to the chemical composition of the rock and is an important intact rock property. It can be identified in the field if samples shrink and crack, or otherwise degrade upon drying, or being exposed to air for several hours. If degradation of the rock sample occurs, and slaking is suspected; an air dried sample may be placed in clean water to observe a reaction. The greater the tendency for slaking the more rapid the reaction will be when immersed in water. This tendency should be expressed on the field logs as "potential for slaking", and can be confirmed through laboratory testing.

4.2 VOIDS

Voids are an important discontinuity property to note in the field logs. They are defined as relatively large open spaces within the rock mass caused by chemical dissolution or the action of subterranean water within the rock mass. In addition, voids can be a result of subsurface mining activities. Voids, when encountered, should be recorded on the field logs. Attempts should be made to determine the size of the void by drilling action, water loss, etc.

4.3 LOSS OF CIRCULATION

Loss of coring fluid can indicate a major discontinuity, change in materials, or void in the drill hole.

Note the depth, time, and approximate amount of fluid loss when the driller loses circulation of drilling fluids.

WY NPS YELL 10(24)

SECTION 5 – REFERENCES

Deere, D.U., 1989. RQD After Twenty Years. USACE Contract Report GL-89-1. Waterways

Experiment Station, Vicksburg, MS. pp. 101.

Geologic Society of London. 1977. The description of rock masses for engineering purposes:

report by the geological society engineering group working party: Quarterly Journal of Engineering Geology. Vol. 10, Great Britain. pp 355-388.

International Society for Rock Mechanics (ISRM). 1978. Commission on Standardization of Laboratory and Field Tests. Suggested Methods for the Quantitative Description of Discontinuities in Rock Masses, International Journal of Rock Mechanics, Minerals, Science, and Geomechanics Abstract. Vol. 15, pp 319-368.

ISRM, 1981 Committee on standardization of laboratory and field tests. Suggested Methods:

Rock characterization testing, and monitoring. E.T. Brown, ed. Pergamon Press, London, Great Britian, pp 211.

Ulusay, R. and Hudson, J.A., 2007. The Complete ISRM Suggested Methods for Rock Characterization, Testing and Monitoring: 1974-2006. Compilation arranged by the ISRM Turkish National Group on behalf of ISRM (Ankara, Turkey). Printed by Kozan Offset Matbaacilik San. Ve Tic. Sti., Ankara, Turkey. pp 628.

United States Department of Transportation – Federal Highway Administration (USDOT-FHWA).

November 1991. Rock and Mineral Identification for Engineers. Publication No. FHWA-HI-91-

025. pp 50.

USDOT-FHWA, April 2002. Geotechnical Engineering Circular No. 5. Evaluation of Soil and Rock Properties. Publication No. FHWA-IF-02-034. pp 195-229.

WY NPS YELL 10(24)

SECTION 5 – REFERENCES