Search

This paper describes about field study as well as laboratory test performed for the geotechnical properties of rock and soil along the Tinpiple-Banchare Dada road alignment. The purpose of the present study was to determine the geotechnical properties for both rocks and soils along the road alignment. Detailed geotechnical soil/rock field study sheets were used to record geotechnical parameters in the field and to know the site condition. Dynamic cone penetration test was performed in the in situ soil. Laboratory test were performed for the classification of the soil, and to determine the optimum moisture content. Results reveal that most part of the road is aligned through the completely weathered sandstone, its residual soil (classified as SM) along with the gneisses. The results of the Dynamic Cone Penetration Test show that minimum CBR % varies from 18% at 10 cm depth to 2% at 58 cm. These values of the CBR % are considered good so no capping is required. The results of the compaction test show that maximum dry density for most of the samples were obtained at 10-15 % optimum moisture content. The results of the joint analysis revealed that chainage 2+ 115, 2+475, 5+125 to 5+ 175 and 7+220 km has probability of lateral, lateral / central, central and central wedge failure respectively. Small landslides were initiated in upslope side due to road cutting and can be stabilized by simple bioengineering techniques. The results of this study are very important for the construction of a sound road and should be considered during the full phase onstruction of the road., 紀要論文

F E modeling under plane stress condition is used to analyze the state of stress in and around the San Andreas Fault (SAF) System taking whole area of California. In this study we mainly focus on the state of stress at the general seismogenic depth of 12 km, imposing elastic rheology. The purpose of the present study is to simulate the regional stress field, displacement vectors and failures. Stress perturbation due to major fault, its geometry and major branches are analyzed. Depthwise variation from 20 km to 0.5 km is considered for the fault type analysis. Series of calculations are performed with \nthe parametrical variations of domain properties and are applied for the strong/weak SAF. All the simulated results are finally utilized for the implication of present day plate kinematics. Although in nature there is lateral and vertical variation in rheology within single domain and different domains (not considered in this study), our simulated results are comparable with the observed data. The imposed boundary condition (fixed North American plate, Pacific plate motion along N34°W vector up to northern terminus of the San Andreas faults and N50°E vector motion for the subducting Gorda and Juan de Fuca plates) had simulated the present day regional σHmax orientation and displacement vector. Simulated results show some local effect on the stress field and displacement vector by the main strand of the fault and probably its geometry and branch (Garlock Fault). Probably the low angle σHmax orientation to the strike of the SAF system in the South California (although there are some high angle σHmax orientation in southeastern California) compare to the central and northern California is due to the big bend and the Garlock Fault. This modeling had also beautifully simulated the left lateral strike slip movement on the Garlock Fault. Failure analysis performed based on Byerlee's law directly test the strong SAF and variation of physical parameters in the Mohr-Coulomb failure criterion is utilized to test relatively strong/weak SAF. Our simulated results (like stress, displacement vector, and failures) in the weak fault in relatively strong crust conditions has more or less reproduced comparable and theoretically correct results, allowed us to favor weak fault in relatively strong crust. Depthwise variation of the fault type reveal that as the depth increases, the fault types are generally normal and shallow depth gives more strike slip and thrust fault. In conclusion SAF may terminate as a normal fault at the depth., 紀要論文

The Tinpiple-Banchare Dada road is located northwest of the Kathmandu valley. Since the area is a mountainous terrain consisting of varieties of slopes, development activities may be threatened by landslide related phenomena. Recently, Kathmandu Metropolitan City (KMC) and Ministry of Local Development are jointly constructing the access road (Tinpiple-Banchare Dada Road) for the mobilization of the solid wastes collected from the KMC. It is, therefore, desirable to have engineering geological studies along the road alignment. This paper describes the methodology used in preparing the engineering geological map along the road. The purpose of the present study was to prepare an engineering geological map along the road alignment and to determine the geotechnical properties for both rocks and soils. For these purposes, the required attributes for engineering geological studies were identified and are mapped in the field. Soil and rock samples were analyzed for different engineering parameters. Results reveal that the most part of the road is aligned through the completely weathered sandstone, its residual soil along with the gneisses. The result reveals that areas with 3-6 meter thick soil may be hazardous in terms of landslides and should be avoided, if possible., 紀要論文