Evaluation of antecedent rainfall effects in the analysis of the probability of transient failure in unsaturated slopes

The occurrence of extreme events of precipitation is commonly responsible for inducing surface mass movements in slopes. Landslides are due to the soil-atmosphere interactions. The main inducer of failure in unsaturated slopes is the infiltration, which triggers the reduction of suction, favoring the decrease of stability. Thus, this paper presents the implementation of analytical models to evaluate the probability of transient failure of slopes under unsaturated conditions for a local scale when subjected to antecedent precipitation. In this sense, the model proposed involves an analytical solution to Richards equation for unsaturated flow under transient conditions, capable of analyzing the soil behavior in the infiltration process. Therefore, these analytical models and the geotechnical parameters taken from the case study of a landslide that occurred in Nova Friburgo (Brazil) allowed the simulation of the infiltration process using the precipitation data corresponding to the day of the landslide, as well as four months previous to the collapse. The calculation routine is capable of generating the decreasing performance of the transient factor of safety and the increasing probability of transient failure through a probabilistic approach, allowing easy predicting failure and management of threat of landslides.

An Evaluation of Submarine Collisions to a TLP

An engineering study was performed in 2017 to develop a multi-span suspension bridge on floating foundations across the Bjørnafjorden in Norway. The bridge was approximately five kilometers long and consisted of three main suspension spans supported by four pylons (towers). Two of the pylons were supported on tension-leg platforms (TLP) due to large water depths. The bridge has to be resistant towards collisions from passing ships. However, submarine impacts to the submerged parts of the bridge were also a challenge due to the bridge location being close to an active submarine training field. This paper focus on the response of one such TLP towards collisions from submarines transiting below the bridge. Nonlinear explicit finite element analysis is used to study the possible collision scenarios, and the response of the TLP and the resulting bridge motion is evaluated. Further, transient failure of a tether was investigated to assess possible consequences of rupture of one of the tethers.

Simulation Design of Monitoring System on Aircraft Sudden Failure

The sudden failure is a transient failure. Its occurrence time is short and it is very difficult to prevent. In order to prevent the sudden failure on aircraft, a monitoring project is presented. It is based on the mechanism analysis of aircraft sudden failure and the evolvement parameters of sudden failure are used Simulation monitoring system is designed by an example of engine surge at the same time. Results shown that this method can effective prevent occurrence of sudden failure by adjustment of the evolvement parameters on aircraft sudden failure.