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No.73 (2002/3) >

 
Title :Stress Distribution and Fault Development Around Nepal Himalaya by Means of Finite Element Method
Authors :Alam, Md. Mahmudul
Hayashi, Daigoro
Authors alternative :林, 大五郎
Issue Date :Mar-2002
Abstract :There are a number of methods to analyse geological structures. Finite element method is one of them. Numerical modeling based on finite element analysis is an effective tool for studying the elastic behaviors of earth's crust due to tectonic movement. This study describes how to use an advanced numerical modeling technique, the finite element method, to compute rock deformation and to predict stress and fault development as a function of material properties, cohesion and friction angle. Stress distribution and fault development of 2 dimensional plane strain FEM models of four Himalayan cross sections are described. SW (south west) to NE (north east) horizontal shortening up to maximum 375 m (equivalent displacement at 7.5 cm/yr of 5000 yr) is applied at the southwestern end of the cross-sections. Proposed models show that the direction of maximum principal stresses (σ_1) are horizontal along the shallower part of all the models. Variation of the velocity boundary condition indicates the changes of direction of principal stresses along the deeper part while that along the shallower part remain unchanged. According to the Mohr - Coulomb criterion, failure is observed along the shallower part of Siwalik, Tethys and Granitic layer, and a very few near the surface of MBT, MCT and STDS. Failure has not occurred in the deeper part of Higher Himalaya and Lesser Himalaya, inspite of changing physical parameters of rock formations, because of the hydrostatic condition that is observed along the models. Previous studies on focal mechanism solutions of earthquakes in the Himalayan region provide the existence of thrust faults along its EW stretching with one plane dipping gently north beneath the Himalaya. Simulation shows the same distribution of thrust faults along the upper part of the models as shown by the focal mechanism solutions.
Type Local :紀要論文
ISSN :0286-9640
Publisher :琉球大学理学部
URI :http://hdl.handle.net/20.500.12000/2621
Citation :琉球大学理学部紀要 = Bulletin of the College of Science. University of the Ryukyus no.73 p.15 -54
Appears in Collections:No.73 (2002/3)

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