The development of early warning systems for landslide hazards has long been a challenge because the accuracy of such systems is limited by both the complicated underlying mechanisms of landslides and the lack of in situ data. In this study, we implemented a multivariate threshold criterion that integrates in situ monitoring data and data from unsaturated hydro-mechanical analyses as an early warning system for rainfall-induced landslides in the Wenchuan earthquake region of China. The results indicate that rainfall intensity is closely correlated with the probability of landslide occurrence. Variations in matric suction and suction stress were obtained from in situ measurements and used to quantify the soil water retention curve, which presented clear hysteresis characteristics. The impacts of rainfall infiltration on slope failure in post-earthquake landslide areas under transient rainfall conditions were quantified by hydro-mechanical modelling theories. Variations in the suction stress of unsaturated soil were used to calculate the safety factor. The influence of hydrological hysteresis processes on the slope failure mechanism was analysed. Multivariate threshold criteria that include the intensity–probability (I-P) threshold, soil moisture and matric suction based on in situ big data and unsaturated slope stability analysis benchmarks are proposed for use in an early warning system for rainfall-induced landslides.
Ti-6Al-4V alloy is extensively used in the manufacture of components in aviation. In the current study, the laser welding process is adopted to joint the Ti-6Al-4V alloy plate which has the thick of 8 mm. A three-dimensional finite element model is established to simulate the temperature distribution of laser welding process. The thermal cycle curves are produced on the strength of the simulation results. Meanwhile, the microstructure characteristics of the welded joint are investigated combined with simulation results. The results show that weld zone, heat affected zone and based metal experience similar thermal cycles process and the cooling rate has an important influence on the formation of microstructure. Moreover, the simulation results are well matched with experiment results. 相似文献
The hot deformation behavior and workability of a new reduced activation ferritic/martensitic steel named SIMP steel for accelerator-driven system were studied.The flow curve and its microstructure were studied at 900-1200℃ and strain rate range of 0.001-10 s~(-1).The results showed that the deformation behavior of the SIMP steel during hot compression could be manifested by the Zener-Hollomon parameter in an exponent-type equation.Based on the obtained constitutive equation,the calculated flow stresses were in agreement with the experimentally measured ones,and the average activity energies QDRV and QHW for the initiation of dynamic recrystallization and the peak strain were calculated to be 476.1 kJ/mol and 462.7 kJ/mol,respectively.Furthermore,based on the processing maps and microstructure evolution,the optimum processing condition for the SIMP steel was determined to be 1050-1200 ℃/0.001-0.1 s~(-1). 相似文献