A Scale-Effect Index for the Deformation Behavior of Rock Masses

• Main Authors: Chen Jain-Jong, 陳建仲
• Other Authors: Yang Zon-Yee
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/96479692111024949448

碩士 === 淡江大學 === 土木工程研究所 === 83 === The mechanical properties of the rock material and the jointed rock are anisotropic due to the pre-existing cracks and joints. To well predict the behavior of the prototype by the model behavior, the failure modes and failure mechanism between pro- totype and model must be similar to the scale effect due to local failure. The deformation of the jointed rock masses is mainly controlled by the behavior of the slip and rotation of the rock block materials. When the rotation deformation of rock block, blocky material clearly show that moment transfer(couple moment) is important mode of load transfer and depends on defor- mation mechanism. The proportional value of the characteristic length and the contact area of blocky rock is used to evaluate the scale effect on the various types of jointed rock masses in this research. Therefore, the degree of scale effect on the rock mass of various classes is evaluating. Some conclusions are drawn from this reasearch: (1) The characteristic length of horizontal formation is more larger than that of dip formation. (2) Based on the comparison of joint spacing and its calculating characteristic length for various class rock masses, it finds that the scale effect is marked in the rock mass of class-IV. (3) The scale effect is obvious in the smaller scale of tunnel and in the cases of class-V rock mass with square blocks. The marked scale effect is observed for the larger scale tunnel in the class of rock mass with slender blocks. (4) The degree of scale effect by rotation deformation is dependent of block shape, stack pattern, dip angle and overburden of the rock masses.