尼德克眼底照相机海报:Environmental Geology of Limestone in Malaysia4

2.2 Rockfalls
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Rockfalls and rockslides are major engineering geologic problems associated with limestone hills. The steep-subvertical and often overhanging limestone cliffs are potentially hazardous in terms of rock slope stability, and numerous major incidences of rockfalls have been investigated and documented by the Geological Survey Department in the past (e.g. Shu et al., 1981; Shu and Lai, 1980). In the survey of limestone hills in the Kinta Valley area, numerous minor occurrences of rockfalls and potential rockfall sites were also documented by me (Tan, 1988), in addition to the major ones previously documented by the Geosurvey. Besides structural control by joints, faults and bedding planes, other significant contributing factors to rockfalls include blasting operations in nearby quarries (vibrations and gas expansions into fracture planes).
2.3 Rockfall hazards zonation--the Tambun Hills
An investigation into the potential rockfall hazards in the limestone hills of the Tambun area has been conducted recently (Tan, 1998b). The objectives of the study
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were to identify and categorise the various limestone cliffs into various hazards zones, so as to aid in the planning of development and construction around these hitlls. The methodology adopted involved ranking the various cliff faces in terms of stability by considering both the geological structures and the solution features. A 3-zone classification scheme was used to denote stable/low hazard, moderately stable/moderate hazard, and unstable/high hazard zones, producing a hazard zonation
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map for planning purposes. Some typical results of the study are shown in Table 1 and Fig. 1.Details can also be referred to in Tan (1998b).
Among other things, one of the conclusions of the study was that the north-south-trending bedding planes of the limestone hills in the Tambun area are the major structural features controlling the morphology and the stability of the cliff faces. The so-called Tambun Tower is one good example.