to contractor as per his contrac- to excavate these materials. The excavatability. Rippability is often
tual obligations and design re- rippability of rock has been a qualitatively classified into three
quirement. It was came to know continuous problem in the Geol- categories, namely, rippable,
that this loss was purely lack of ogy and Construction Programs. marginal, and non-rippable. The
knowledge on understanding the Knowledge of Rippability of Rock main concerns in construction in
Soil Report Investigation details, is an important aspect to assess rock areas are the overall cost of
Rippability of Soil type and start- the excavation work planning the project, serious project de-
ing the excavation work without and pricing correctly. Accurate lays reflected in the bill of quan-
proper assessment especially for evaluation of rock rippability and tities, tender, and claims that
rock type soils.
prediction of the excavation effort lead to the abandonment of the
Lack of understanding on this through a better understanding of site in the preliminary stage. As-
matter, and with deficiencies in their properties will improve the sessment types of Rock masses
the existing specifications on preparation of both construction excavatability systems are (a).
earthwork, excavation in some schedule and cost estimation, Seismic velocity determination
rocks may lead to disputes be- facilitate the selection of proper ;( b).Size-Strength Method; (c).
tween project owner and con- ripping equipment, and maxi- RMR
System;
(d).Weaver's
tractor. Issues are mainly con- mize production. These uncer- (1975) Rippability Rating Sys-
fined to the classification of hard tainties include the selection of tem; (e).McGregor et al (1994)
materials encountered, and the the excavation method, the types Productivity Prediction Method.
justifications for adopting ripping of machineries, and the rate of
a/ Because ripping index, kn, of Ripping (1997).
cavation in NRCS Construction
(Kirsten, 1988) is equal to c/ Flywheel horsepower, ma- Specification 21, Excavation.
head cut Erodability index, kh chines assumed to be heavy-du- e/ Meets criteria for rock excava
(NEH628.52), use kh.
ty, track-type backhoe or tractor tion in NRCS Construction Spec-
b/ Seismic velocity values are equipped with a single tooth, ification 21, Excavation.
approximate, taken from ASTM rear- mounted ripper.
Note: The classification is a
D5777 and Caterpillar Handbook d/ Meets criteria for common ex- general guide and does not
Articles
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