Institut Teknologi Medan Jurusan Teknik PertambanganFORM PELAPORAN DESKRIPSI KONDISI MASSA BATUAN

ROCK MASS DESCRIPTION AND CLASSIFICATIONPage : _____of ______ Date :Logged By :

LOCATION :

1. ROCK TYPE

2. INTACT ROCK MATERIALUCS : ___________________________MPaSchimdt Hammer : _________________ MPaDensity : _________________________Kg/m3FIELD INDEX STRENGHTExtremly weak rock 0.25 1 MPa : ________Very weak rock 1 5 MPa : _____________Weak rock 5 -25 MPa : _________________Medium strongth rock 25 50 MPa : ______Stronght rock 50 100 MPa : ____________Very strongth rock 100 250 MPa : _______Extremely strongth rock > 250 MPa : ______3. WEATHERINGCompletly weathered : ____________Highly weathered : _______________Moderatly weathered : ____________Slightly weathered : ______________Fresh : ________________________Other Description : ______________

4. GROUND WATER CONDITIONDry : ________ Dripping : _________Wet : ________ Flow : ____________Other Description : _______________5. BLASTING CONDITION

9. CLASSIFICATION9.1 ROCK MASS QUALITY = Rock Description :

9.2 ROCK MASS RATING (RMR)RMR = UCS + RQD + Spacing + Jcond + GW Orient =

Rock Description :

9.3 SLOPE MASS RATING (SMR)SMR = RMR + (F1 x F2 x F3 x F4) =

Rock Description :

6. ROCK MASS DISCONTINUITIES

Joint NoType & LengthOrientationInfillRoughnessAlterationTerrminationLineation

StrikeDipTypeSizeThick12TypeTrendPlunge

1.

2.

3.

4.

5.

7. RQD EQUIVALENT

RQD = 115 3.3 Jc = Jc =

8. Rock Mass PropertiesConstant mi =

Geological Strenght Index (GSI) =

ROCK MASS RATING (RMR)A.CLASSIFICATIONPARAMETERSANDTHEIRRATINGS

ParameterRangeofvalues

1StrengthofintactrockmaterialPoint-loadstrengthindex>10MPa4-10MPa2-4MPa1-2MPaForthislowrange-uniaxialcompressivetestispreferred

Uniaxialcomp.strength>250MPa100-250MPa50-100MPa25-50MPa5-25MPa1-5MPa 50 m)G. Loose open joints, heavily jointed or 'sugar cube', (any depth)

b. Competent rock, rock stress problems

H. Low stress, near surfaceJ. Medium stressK. High stress, very tight structure(usually favourable to stability, maybe unfavourable to wall stability)L. Mild rockburst (massive rock)M. Heavy rockburst (massive rock)

c. Squeezing rock, plastic flow of incompetent rock under influence of high rock pressure

N. Mild squeezing rock pressureO. Heavy squeezing rock pressure

d. Swelling rock, chemical swelling activity depending on presence of water

P. Mild swelling rock pressureR. Heavy swelling rock pressure

c/1 t.1

>200 >13200-10 13-0.6610-5 0.66-0.33

5-2.5 0.33-0.16>2.5 >0.16SRF

10.0

5.0

2.5

7.5

5.0

2.5

5.0

2.51.00.5-2

5-1010-20

5-1010-20

5-1010-15

1. Reduce these values of SRF by 25 - 50% butonly if the relevant shear zones influence donot intersect the excavation

2. For strongly anisotropic virgin stress field(if measured): when 51/310, reduce c to 0.8c and t to 0.8t. When 1/3 > 10, reduce c and t to 0.6c and 0.6t, c = unconfined compressive strength, andt = tensile strength (point load) and 1 and3 are the major and minor principal stresses.3. Few case records available where depth ofcrown below surface is less than span width.Suggest SRF increase from 2.5 to 5 for such cases (see H).

ADDITIONAL NOTES ON THE USE OF THESE TABLESWhen making estimates of the rock mass Quality (Q), the following guidelines should be followed in addition to the notes listed in thetables:1. When borehole core is unavailable, RQD can be estimated from the number of joints per unit volume, in which the number of jointsper metre for each joint set are added. A simple relationship can be used to convert this number to RQD for the case of clay freerock masses: RQD = 115 - 3.3 Jv (approx.), where Jv = total number of joints per m3 (0 < RQD < 100 for 35 > Jv > 4.5).2. The parameter Jn representing the number of joint sets will often be affected by foliation, schistosity, slaty cleavage or bedding etc. Ifstrongly developed, these parallel 'joints' should obviously be counted as a complete joint set. However, if there are few 'joints'visible, or if only occasional breaks in the core are due to these features, then it will be more appropriate to count them as 'random'joints when evaluating Jn.3. The parameters Jr and Ja (representing shear strength) should be relevant to the weakest significant joint set or clay filleddiscontinuity in the given zone. However, if the joint set or discontinuity with the minimum value of Jr/Ja is favourably oriented forstability, then a second, less favourably oriented joint set or discontinuity may sometimes be more significant, and its higher value ofJr/Ja should be used when evaluating Q. The value of Jr/Ja should in fact relate to the surface most likely to allow failure to initiate.4. When a rock mass contains clay, the factor SRF appropriate to loosening loads should be evaluated. In such cases the strength ofthe intact rock is of little interest. However, when jointing is minimal and clay is completely absent, the strength of the intact rock maybecome the weakest link, and the stability will then depend on the ratio rock-stress/rock-strength. A strongly anisotropic stress fieldis unfavourable for stability and is roughly accounted for as in note 2 in the table for stress reduction factor evaluation.5. The compressive and tensile strengths (c and t) of the intact rock should be evaluated in the saturated condition if this isappropriate to the present and future in situ conditions. A very conservative estimate of the strength should be made for those rocksthat deteriorate when exposed to moist or saturated conditions.

ROCK STRUCTURE RATING (RSR)

Rock Structure Rating, Parameter A: Daerah Geologi Umum

BasicRockTypeGeologicalStructure

IgeneousMethamorphicSedimentaryHard112Medium223Soft334Decomposed444MassiveSlightlyorFoldedModeratelyFaultedorFoldedIntenselyFaultedorFolded

Type1Type2Type3Type43027241922201815151312109876

Rock Structure Rating, Parameter B: Pola Kekar, Arah PenggalianAverageJointSpacingStrike toAxisStrikeIItoAxis

DirectionofDrive

Both WithDip Against Dip Dip of Prominent Joints a FlatDippingVerticalDipping VerticalDirectionofDrive Either direction

Dip of Prominent Joints

FlatDipping Vertical

1.Verycloselyjointed,4ft91113101213161915172324281922323625283038403335364043453740997141411232319302824363428403834

a After Wickhman et.al., (1974). b Dip : flat : 00-200; dipping : 200-500; and vertical : 500-900.Rock Structure Rating, Parameter C : Air Tanah, Kondisi KekarSumofParametersA+B1344 45-75Anticipatedwaterinflow JointConditionbgpm/1000ftoftunnel Good FairPoorGoodFair PoorNone 22 1812252218Slight,1000gp 10 8 6 18 14 10

a After Wickhman et al. (1974) b Joint condition :good = light or cemented: fair = sligthly weathered or altered : poor severely weathered, aftered, or open.

Joint Orientasi

Spasi rata-rata Joint :

Gambar Jarak Bidang Kekar dan Pengukuran Jarak Bidang Kekar di Lapangan

Joint OrientationNo. JointStrikeDipNo. JointStrikeDip