Characteristic behaviour of slow moving slides.

摘要

The vulnerability and movement behaviour of slow moving slides are investigated. The study focuses on slides moving at rates ranging from a few millimetres a year like extremely slow slides, to 13 meters per month, the upper velocity range of slow slides. An extensive review of the effect of pore pressure changes on movement reactivation of shallow and moderately thick slides is presented. The time dependent behaviour of fine geotechnical materials is also reviewed.;Although the literature has reported many cases where the accumulation of slow movements led to a complete collapse of buildings, failure of embankment slopes carrying highways or railways and serviceability problems for dams and bridges, little attention has been paid to the vulnerability to slow moving slides. Hence, this thesis aims to provide more insight into the actual damage to facilities founded on slow moving slides. More than fifty cases of extremely slow, very slow and slow slides adversely affecting urban communities, highways, railways, bridges, dams and linear infrastructure are reviewed. The survey enables the development of new damage-extent scales that use the slide velocity to help assess the degree of damage to a facility founded on a landslide-prone area.;Vulnerability is an important component of the specific risk. The other component is the hazard or the probability of occurrence of a certain damaging phenomenon like landslides. Defining the causal factors of the landslide movements and their contributions to the total movement is an important step towards the evaluation of the hazard. Hence, the geomechanical behaviour of two typical deep-seated and moderately thick slides, the Little Chief Slide and the Little Smoky Slide, respectively, are investigated. The objective is to determine all the triggers and causal factors of movement and to quantify their contribution to the total movement. The study involves groundwater flow modeling of one of the two slides, an extensive field monitoring of pore pressures and displacements and an investigation of the creep behaviour both in the field and in the laboratory. The outcome of the study shows that the total movement of each of the two slides can be separated into creep and seasonal movements. The contribution of each component is quantitatively defined. The quantification of the different causal factors aids in choosing the proper mitigation option in addition to predicting the future movement rates after the chosen remedial measures have been installed.