A study on the scale effect of dynamic shear strength between single rock joint
Date Issued
2010
Date
2010
Author(s)
Chen, Li-Wei
Abstract
There are different numbers of joints, which may be formed a sliding plane, for rock mass of rock slope. Depend on the intersection of different joints, the failure type of rock slope are usually quite different, such as the wedge failure which includes multiple sliding planes or a dip slope failure which includes a specific sliding plane. (Ex. Tsao-Ling rockslide.).
The sliding process of a dip slope under seismic excitation has two main factors: 1) normal stress applied on the sliding surface; 2) sliding velocity of rock block along a plane. A severe rock sliding failure could be induced by an infiltration of rain or by an earthquake. In this research, several simplify laboratory experiments are conducted to simulate and to investigate behaviors of “dry fiction” at a sliding interface between two rock blocks. However, the “lubrication effect of friction” and “effect of rain infiltrating into rock” are not included in this thesis.
The friction behavior of sliding block under dynamic condition are presented in this thesis. Nevertheless, there are many influence factors of friction, so the first part of this study is focus on “effect of normal stress” and on “effect of dynamic shear rate” and all the characteristics of experiment results are discussed in this research.
Moreover, the application from results of the laboratory scale tests to the in-situ slope failure analysis is also investigated here. This study could be applied on an analysis of rock slope failure by considering the scale effect on dynamic shear strength.
The direct shear test, which is simulated an in-situ scale test, is conducted with three kinds of conditions which are 1) horizontal dynamic shear test 2) different applied normal stress test and 3) different dynamic shear rate test.
About the small scale shaking table test, three kinds of tests are conducted which are “different slope angle test”, “different applied normal stress” and “different shaking frequency.” In addition, the influences of sliding process of a rock block is also presented here, which includes the trend of friction behavior of a block from static to slide on a plane under seismic excitation and the relationship between a friction coefficient and relative velocity of sliding block or relative displacement of sliding block.
Under these test conditions, such as difference of scale effects, different dynamic shear rate, and different applied normal stress, how to get the scale effect on shear strength using horizontal shear test are presented in this thesis.
Subjects
small scale shaking table test
direct shear test
normal stress
shear rate
Type
thesis
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