During the feasibility and preliminary design stages of a project, when very little detailed information on the rock mass and its geomechanic characteristics is not available, the use of a Rock Mass Classification Scheme (RMCS) can be of considerable benefit. Various parameters were used in order to identify the RMCS. The parameter comprised of Rock Quality Designation (RQD), Rock Mass Rating (RMR), Rock Structure Rating (RSR), Geological Strength Index (GSI), Slope Mass Rating (SMR), etc. In this paper, we present the results of the applicability of the Geological Strength Index (GSI) classification for the Trusmadi Formation in Sabah, Malaysia. The GSI classification system is based on the assumption that the rock mass contains a sufficient number of “randomly” oriented discontinuities such that it behaves as a homogeneous isotropic mass. In this study, the GSI relates the properties of the intact rock elements/blocks to those of the overall rock mass. It is based on an assessment of the lithology, structure and condition of discontinuity surfaces in the rock mass and is estimated from visual examination of the rock mass exposed in outcrops or surface excavations. A total of ten (10) locations were selected on the basis of exposures of the lithology and slope condition of the Trusmadi Formation. The Trusmadi Formation regionally experienced of two major structural orientations NW-SE and NE-SW. It consists mostly of dark grey shale with thin bedded sandstones, typical of a turbidite deposit. This unit has been subjected to low grade of metamorphism, producing slates, phyllites and meta-sediments and intense tectonic deformation producing disrupted or brecciated beds. Quartz vein are quite widespread within the joints on sandstone beds. The shale is dark grey when fresh but changes light grey to brownish when weathered. The results are classified as “Poor Rock” to “Fair Rock” in term of GSI. The poor categories (TR2 and TR7) represent slickensided, highly weathered surfaces with compact coatings or fillings or angular fragments. It is also characterized as blocky/ disturbed/seamy, which folded with angular blocks formed by many intersecting discontinuity sets. The fair categories can be divided into two (2) types; type 1 (TR1, TR6 and TR8) which represent as smooth, moderately weathered and have altered surfaces. It is also characterised as very blocky rock, which indicates interlocked, partially disturbed ass with multi-faceted angular blocks formed by 4 or more joint sets. Type 2 (TR3, TR4, TR5, TR9 and TR10) which represent as smooth, moderately weathered and have altered surfaces but characterized as blocky/disturbed/seamy, which folded with angular blocks formed by many intersecting discontinuity sets. It also has persistence of bedding planes or schistosity.
Rock Mass Classification Systems (RMCS) can be of considerable use in the initial stage of a project when little or no detailed information is available. There is a large number of RMCS developed for general purposes but also for specific applications such as Rock Quality Designation (RQD), Rock Mass Rating (RMR), Rock Structure Rating (RSR), Geological Strength Index (GSI), Slope Mass Rating (SMR), etc. In this paper, we present the results of the applicability of the Rock Mass Rating (RMR) System for the Trusmadi Formation in Sabah, Malaysia. The RMR system is a RMCS incorporated with five (5) parameters: Strength of intact rock material, Rock Quality Designation (RQD), Spacing of joints, Condition of joints, and Groundwater conditions. A total of ten (10) locations were selected on the basis of exposures of the lithology and slope condition of the Trusmadi Formation. Trusmadi Formation is Paleocene to Eocene in aged. The Trusmadi Formation generally shows two major structural orientations NW-SE and NE-SW. Trusmadi Formation is characterized by the present of dark colour argillaceous rocks, siltstone and thin-bedded turbidite in well-stratified sequence. Some of the Trusmadi Formation rocks have been metamorphosed to low grade of the greenish-schist facies; the sediment has become slate, phyllite and metarenite. Cataclastic rocks are widespread and occur as black phyllonite enclosing arenitic and lutitic boudins with diameter up to a meter or demarcating thin to thicker fault zones or as flaser zones with hardly any finer grain matrix or as zones of closely spaced fractures. Quartz and calcite veins are quite widespread within the crack deformed on sandstone beds. The shale is dark grey when fresh but changes light grey to brownish when weathered. The RMR system for 10 outcrops ranges from 33.0 to 50.0 and its classified as “Fair” (Class III) to “Poor” (Class IV) rocks. The Fair Rock (Class III) recommended that the excavation should be top heading and bench 1.5 m – 3 m advance in the top heading. Support should be commencing after each blast and complete support 10 m from face. Rock bolts should be systematic with 4 m long spaced 1.5 m – 2 m in crown and walls with wire mesh in crown. Shotcrete should be 50 mm – 100 mm in crown and 30 mm in sides. While for the Poor Rock (Class IV), the excavation should be top heading and bench 1.0 m – 1.5 m advance in top heading. Support should be installed concurrently with excavation, 10 m from face. Rock bolt should be systematic with 4 m – 5 m long, spaced 1.5 m – 1.5 m in crown and walls with wire mesh. Shotcrete of 100 m – 150 mm in crown and 100 mm in sides. The steel sets should be light to medium ribs spaced 1.5 m only when required.
Landslides are amongst the most damaging natural hazards in Malaysia. The study of landslides has drawn nationwide attention mainly due to increasing awareness of the socio-economic impact of landslides, as well as the increasing pressure of urbanization. Landslide Hazard Identification (LHI) is part of the process used to evaluate if any particular situation, item, thing, etc. may have the potential to cause harm. The description of LHI should include the location, volume (or area), classification and velocity of the potential landslides and any resultant detached material, and the probability of their occurrence within a given period of time. In this paper, we present the results of the measurement for the subsurface resistivity within by using the pole-dipole electrode array and present the 2D view of each resistivity profile. The result presented successfully detect the dominant layer consists of interbedded sandstone and shale of the Crocker Formation with highly weathered. This both layers have high porosity and potential to contain high water content which can trigger landslide to occur. Besides that, there are several boulders zone (weathered to fresh rock) that can be found at the top of the subsurface profile at about 1.5m to 15m in depth. The bedrock layer was estimated to be found at 4m to 32.5m in depth from the original ground and one possible fault line that had been identified. This fault line believed plays a role in the occurrence of landslide in which rock materials have lower strength compared to surrounding rocks. High density of fault means lower stability. Therefore the faut line have been regarded as a critical factor in triggering landslide in the study area. The results of these study findings are expected to be used as uniform guidelines and principles are very useful and have integrity in providing coordination of standards or policies for each planning activities for new development in the future. As a result of the lack of concern for the developer of the concept of Sustainable Development Goals (SDG) or balancing and control of environmental health, the results of this study can also be used as a yardstick to party developers who intend to develop a high ground and hillside in deciding whether to continuing development planning or not.
Landslide issues in Malaysia is successfully attract the interest and attention of stakeholders and the community of scientists to reduce the risk. Landslides are influenced by many factors that range from the intensity, duration and extent of a triggering factor (e.g. earthquake and rainfall) to the local physical conditions such as landform, morphological, geological materials and structures, hydrological and land uses. In this paper, we present the results of the Landslide Vulnerability Assessment (LVAs). Vulnerability is defined as the degree of losses of a given element at risk of being exposed to the occurrence of a landslides of a given magnitude or intensity, and often expressed on a scale of 0 (no loss) to 1 (total loss). The selection of the best LVAs depends on the exposed elements, landslide types and the scale of analysis. The concept of LVAs also refers to the feasibility of elements at risks on engineering structures, infrastructure facilities, communication systems, commercial (including insurance disclosures) and social. The vulnerability parameters include in assessing LVAs in this study are 1) physical implication (building structures, internal materials, property damage, infrastructural facilities and stabilization actions), social status (injury, fatalities, safety, loss of accommodation and public awareness) and interference on environment (affected period, daily operation & diversity). LVAs for study area produced by combining or overlaid of all Physical Vulnerability (Vp), Social Vulnerability (Vs) and Environmental Vulnerability (Ve) maps. The results for the Total of LVAs indicates that 30% (0.90 sq.m) of the study area classified as Very Low, 8% (0.24 sq.m) as Low, 8% (0.24 sq.m) as Moderate, 28% (0.84 sq.m) as High, 8% (0.24 sq.m) as Very High and 18% (0.54 sq.m) as Extremely High. Landslide Vulnerability level at a “high” to “very high” degree can leave an impact on individuals and society. This study found that residential, commercial, public and industrial infrastructure has higher vulnerability rather than the agricultural and forestry areas. This LVAs approach is suitable as a guideline for preliminary development planning, control and manage the landslide hazard / risk in the study area and potentially to be extended with different background environments.
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