scholarly journals Excess pore pressure generation potential within shear zone by means of ring shear tests

Landslides ◽  
2002 ◽  
Vol 39 (3) ◽  
pp. 296-306
Author(s):  
Yasuhiko OKADA ◽  
Kyoji SASSA ◽  
Hiroshi FUKUOKA
Keyword(s):  
Pore Pressure ◽  
Shear Zone ◽  
Excess Pore Pressure ◽  
Shear Tests ◽  
Ring Shear ◽  
Ring Shear Tests ◽  
Excess Pore

scholarly journals Consolidated and Undrained Ring Shear Tests on the Sliding Surface of the Hsien-du-shan Landslide in Taiwan

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Hung-Ming Lin ◽  
Jian-Hong Wu ◽  
Erik Sunarya
Keyword(s):  
Pore Pressure ◽  
Rock Avalanche ◽  
Excess Pore Pressure ◽  
High Water Content ◽  
Sliding Surface ◽  
Shear Tests ◽  
Typhoon Morakot ◽  
Ring Shear ◽  
Ring Shear Tests ◽  
Excess Pore

A new consolidated undrained ring shear test capable of measuring the pore pressures is presented to investigate the initiation mechanism of the Hsien-du-shan rock avalanche, triggered by Typhoon Morakot, in southern Taiwan. The postpeak state of the landslide surface between the Tangenshan sandstone and the remolded landslide gouge is discussed to address the unstable geomorphological precursors observed before the landslide occurred. Experimental results show that the internal friction angle of the high water content sliding surface in the total stress state, between 25.3 and 26.1°, clarifies the reason of the stable slope prior to Typhoon Morakot. In addition, during the ring shear tests, it is observed that the excess pore pressure is generated by the shear contractions of the sliding surface. The remolded landslide gouge, sheared under the high normal stress, rendered results associated with high shear strength, small shear contraction, low hydraulic conductivity, and continuous excess pore pressure. The excess pore pressure feedback at the sliding surface may have accelerated the landslide.

Undrained shear behaviour of sands subjected to large shear displacement and estimation of excess pore-pressure generation from drained ring shear tests

2005 ◽  
Vol 42 (3) ◽  
pp. 787-803 ◽  
Author(s):  
Yasuhiko Okada ◽  
Kyoji Sassa ◽  
Hiroshi Fukuoka
Keyword(s):  
Pore Pressure ◽  
Triaxial Compression ◽  
Excess Pore Pressure ◽  
Compression Tests ◽  
Shear Tests ◽  
Ring Shear ◽  
Ring Shear Tests ◽  
Triaxial Compression Tests ◽  
Undrained Shear ◽  
Excess Pore

Undrained shear behaviour of fine silica and weathered granitic sand subjected to large shear displacement is examined. Parallel experiments using ring shear and the triaxial compression tests on soil specimens through a wide range of initial void ratios were conducted to investigate undrained shear strength as the key factor in the flow-like motion of landslides. The steady-state undrained shear strengths achieved in ring shear tests were, in general, smaller than those in the triaxial compression tests, probably because of the excess pore-pressure generation by grain crushing within the shear zone that occurred in ring shear. Very low steady-state shear strengths were achieved, however, in triaxial compression tests on the dense silica sand in which well-defined shear surfaces developed in the cylindrical specimens. In these triaxial compression tests, shear deformation must have been concentrated on these surfaces to generate excess pore pressure similar to that found in ring shear tests. An attempt was made to estimate excess pore pressure generated in undrained ring shear tests using the results of drained ring shear tests. The equivalent normal stress calculated as the ratio of volumetric strain in the drained test to the coefficient of volume change was introduced as a parameter for the estimation of excess pore-pressure generation for the large shear displacement that is usually found in landslides. Equivalent normal stress from drained tests was almost the same as the generated excess pore pressure in undrained tests with up to 1 m of shear displacement, at which the steady state was reached.Key words: undrained shear strength, excess pore pressure, equivalent normal stress, ring shear test, triaxial compression test, liquefaction.

Evolution of Shear-Zone Structure in Undrained Ring-Shear Tests

Landslides ◽  
2004 ◽  
Vol 1 (2) ◽  
Author(s):  
Muhammad Wafid Agung ◽  
Kyoji Sassa ◽  
Hiroshi Fukuoka ◽  
Gonghui Wang
Keyword(s):  
Shear Zone ◽  
Shear Tests ◽  
Zone Structure ◽  
Ring Shear ◽  
Ring Shear Tests
Sign in / Sign up

Export Citation Format

Share Document