Fault
controls spatial variation offracture density and rock
mass strength within the Yarlung TsangpoFault damage
zone( southern
Tibet)
Xueliang Wanga,b,c*,Giovanni Battista
Crostad*,John J.
Claguee, Douglas Steade, Juanjuan
Suna,b,c, Shengwen Qia,b,c, Haiyang
Liua,b,c
a Key Laboratory of Shale Gas and Geoengineering,
Institute of Geology and Geophysics, Chinese Academy of Sciences,
Beijing 100029, China
b Institutions of Earth Science, Chinese Academy of
Sciences, Beijing 100029, China
c University of Chinese Academy of Sciences, Beijing
100049, China
d Department of Earth and Environmental Sciences,
University of Milano-Bicocca, Milan 20126, Italy
e Department of Earth Sciences, Simon Fraser
University, Burnaby, BC V5A 1S6, Canada
Abstract: The extent of the fault damage zone remains an
outstanding challenge confounding attempts to assess rock mass physical
and mechanical properties, the effects on landscape evolution and slope
stability, and to delineate safe places for human occupation and
infrastructure development. Quantifying the relationship between
faulting and the spatial geometrical and mechanical characteristics of a
rock mass controlled by faulting is difficult, mainly because of varying
lithology and rock mass characteristics, the effects of topography and
vegetation and local erosion of weaker rock mass. Recent technological
developments including Unmanned Aerial Vehicles, terrestrial laser
scanning, photogrammetry and point cloud analysis software tools greatly
enhance our ability to investigate the issues using the Yarlung Tsangpo
(YLTP) Fault of southern Tibet as
a case study where ideal geological conditions exist to investigate the
relationship. In this study, the procedures, investigation approaches,
evidence and criteria for defining the threshold distance for damage
zones of YLTP Fault of southern Tibet were studied quantitatively by
combining the spatial variations of fracture density, rock mass
strength, rockfall inventory and previous thermal evidence. The results
have been compared with published data from the evidence of thermal
effects related to the exactly the same fault and show a good match
between internal thermal action and rock mass physical and mechanical
properties controlled by the same faulting. The extent of threshold
distance of damage zone of the YLTP Fault is estimated as 5.9±0.6km.
Within the damage zone, fracture density and cohesion of the rock mass
show power curve relations with distance from the YLTP Fault. The
internal dynamic action of fault controls rock mass physical and
mechanical properties in the study area. The fault first affects the
characteristics of rock mass structures, and then the orientation of the
rock structures influences the stability of slope leading to rockfall.
Keywords: Fault damage zone, rock mass strength, fracture
density, rockfall, southern Tibet.