Influences of pre-existing fracture on ground deformation induced by normal faulting in mixed ground conditions

Physical model tests have been conducted by various researchers to investigate fault rupture propagation and ground deformation induced by bedrock faulting. However, the effects of pre-existing fracture on ground deformation are not fully understood. In this work, six centrifuge tests are reported to investigate the influence of pre-existing fracture on ground deformation induced by normal faulting in sand, clay and nine-layered soil with interbedded sand and clay layers. Shear box tests were conducted to develop a filter paper technique, which was adopted in soil model preparation to simulate the effects of pre-existing fracture in centrifuge tests. Centrifuge test results show that ground deformation mechanism in clay, sand and nine-layered soil strata is classified as a stationary zone, a shearing zone and a rigid body zone. Inclination of the strain localization is governed by the dilatancy of soil material. Moreover, the pre-existing fracture provides a preferential path for ground deformation and results in a scarp at the ground surface in sand. On the contrary, fault ruptures are observed at the ground surface in clay and nine-layered soil strata.

[1]  R. F. Scott,et al.  Centrifuge modeling of fault propagation through alluvial soils , 1981 .

[2]  H. Seed,et al.  1 g Small-Scale Modelling of Saturated Cohesive Soils , 1993 .

[3]  D. Wood,et al.  Effects of dilatancy and particle size observed in model tests on sand , 1992 .

[4]  W. Powrie.  Soil Mechanics , 2018 .

[5]  Charles Wang Wai Ng,et al.  Centrifuge modeling of loose fill embankment subjected to uni-axial and bi-axial earthquakes , 2004 .

[6]  W. A. Take,et al.  Soil deformation measurement using particle image velocimetry (PIV) and photogrammetry , 2003 .

[7]  Mark Randolph,et al.  An image-based deformation measurement system for the geotechnical centrifuge , 2005 .

[8]  P. Lade,et al.  Influence Zones in Alluvium Over Dip‐Slip Faults , 1984 .

[9]  M. F. Bransby,et al.  Interaction of Shallow Foundations with Reverse Faults , 2009 .

[10]  D. Wells,et al.  New empirical relationships among magnitude, rupture length, rupture width, rupture area, and surface displacement , 1994, Bulletin of the Seismological Society of America.

[11]  H. Seed,et al.  EARTHQUAKE FAULT RUPTURE PROPAGATION THROUGH SOIL , 1994 .

[12]  J. Lienkaemper,et al.  Factors affecting the recognition of faults exposed in exploratory trenches. Bulletin , 1991 .

[13]  P. Lade,et al.  Multiple Failure Surfaces Over Dip-Slip Faults , 1984 .

[14]  M. F. Bransby,et al.  Fault Rupture Propagation through Sand: Finite-Element Analysis and Validation through Centrifuge Experiments , 2007 .

[15]  C. R. Allen,et al.  Potentially active faults in dam foundations , 1974 .

[16]  C. Ng,et al.  Investigation of Boundary Conditions for Simulating Normal Fault Propagation in Centrifuge , 2010 .

[17]  Jeawoo Lee,et al.  AN EXPERIMENTAL STUDY ON EARTHQUAKE FAULT RUPTURE PROPAGATION THROUGH A SANDY SOIL DEPOSIT , 2005 .