Norbert Simon

The geomechanical strength of carbonate rock in Kinta valley, Ipoh, Perak Malaysia

The stability of both cut rocks and underground openings were influenced by the geomechanical strength of rock materials, while the strength characteristics are influenced by both material characteristics and the condition of weathering. This paper present a systematic approach to quantify the rock material strength characteristics for material failure and material & discontinuities failure by using uniaxial compressive strength, point load strength index and Brazilian tensile strength for carbonate rocks. Statistical analysis of the results at 95 percent confidence level showed that the mean value of compressive strength, point load strength index and Brazilian tensile strength for with material failure and material & discontinuities failure were 76.8 ± 4.5 and 41.2 ± 4.1 MPa with standard deviation of 15.2 and 6.5 MPa, respectively. The point load strength index for material failure and material & discontinuities failure were 3.1 ± 0.2 MPa and 1.8 ± 0.3 MPa with standard deviation of 0.9 and 0.6 MPa, respectively. The Brazilian tensile strength with material failure and material & discontinuities failure were 7.1 ± 0.3 MPa and 4.1 ± 0.3 MPa with standard deviation of 1.4 and 0.6 MPa, respectively. The results of this research revealed that the geomechanical strengths of rock material of carbonate rocks for material & discontinuities failure deteriorates approximately ½ from material failure.

Landslide Susceptibility Analysis (LSA) using Deterministic Model (Infinite Slope) (DESSISM) in the Kota Kinabalu Area, Sabah, Malaysia

Deterministic slope stability (DSS) infinite slope model (ISM) landslide susceptibility analysis (LSA) failure probability A practical application for landslide susceptibility analysis (LSA) based on two dimensional deterministic slope stability (infinite slope model) (DESSISM) was used to calculate factor of safety (FOS) and failure probabilities for the area of Kota Kinabalu, Sabah. LSA is defined as quantitative or qualitative assessment of the classification, volume (or area) and spatial distribution of landslides which exist or potentially may occur in an area. In this paper, LSA value can be expressed by a FOS, which is the ratio between the forces that make the slope fail and those that prevent the slope from failing. An geotechnical engineering properties data base has been developed on the basis of a series of parameter maps such as effective cohesion (C’), unit weight of soil (), depth of failure surface (Z), height of ground water table (Zw), Zw/Z dimensionless (m), unit weight of water (w), slope surface inclination (β) and effective angle of shearing resistance (). Taking into consideration the cause of the landslide, identified as groundwater change, the maximum groundwater level recorded corresponding to the actual situation of the most recent landslide is considered in this study. The highest probability value of the various scenarios was selected for each pixel and final LSA map were constructed. It has been found from this study that β and Zw parameters have the higher influence on landslide instability. The result validation between the examined LSA map and result of landslide distribution map (LDM) were evaluated. This DESSISM had higher prediction accuracy. The prediction accuracy is 84%. The resulting LSA maps can be used by local administration or developers to locate areas prone to landslide area, determine the land use suitability area and to organize more detailed analysis in the identified “hot spot” areas.

Development of empirical correlation of peak friction angle with surface roughness of discontinuities using tilt test

The significant influence of surface roughness of discontinuity surfaces is a quantity that is fundamental to the understanding of shear strength of geological discontinuities. This is due to reason that the shear strength of geological discontinuities greatly influenced the mechanical behavior of a rock mass especially in stability evaluation of tunnel, foundation, and natural slopes. In evaluating the stability of these structures, the study of peak friction angle (Φpeak) of rough discontinuity surfaces has become more prominent seeing that the shear strength is a pivotal factor causing failures. The measurement of peak friction angle however, requires an extensive series of laboratory tests which are both time and cost demanding. With that in mind, this publication presents an approach in the form of an experimentally determined polynomial equation to estimate peak friction angle of limestone discontinuity surfaces by measuring the Joint Roughness Coefficient (JRC) values from tilt tests, and applying ...

Soil properties of crocker formation and its influence on slope instability along the Ranau-Tambunan highway, Sabah

The Crocker formation on the study area consists of an inter-bedded shale and sandstone. The intense deformation and discontinuity on sandstone and shale beds of the arenaceous Crocker Formation makes them easily exposed to weathering and instability. In this study, a total of 15 selected slopes representing highly weathered material of stable and unstable conditions were studied to identify the characteristics of soil material on both conditions and how these characteristics will lead to instability. Physical properties analysis of soil material were conducted on 5 samples from stable slopes and 10 samples from failed slopes collected along the Ranau-Tambunan highway (RTM), Sabah. The analysis shows that the Crocker Formation consists mainly of poorly graded materials of sandy SILT with low plasticity (MLS) and PI value ranges from 1%-14. The failures materials are largely consist of low water content (0.94%-2.03%), higher finer texture material (11%-71%), intermediate liquid limit (21%-44%) and low plas...