Field reconnaissance, geological mapping and photographic interpretation are utilized to study the failure mechanisms of July 2 catastrophic debris slide in 2017. The results suggested that the landslide was a reactivation of an ancient landslide after periods of relative dormancy, as manifestation of a retrogressive motion, which is triggered by the continuous engineering excavation as leads to rock mass unloading and decrease of mechanical properties of rock-soil mixture. The reactivated zone dominantly spread on the upper part of the ancient landslide area. The frequent tectonic movements rendered the potential landslide zone by fragmenting the structure. The fractured and fissile rock mass became further weakened by incessant rainfall that finally led to the failure of the rock mass. ARTICLE HISTORY

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This paper introduced the control strategy of back-toback full-scale PWM converter in direct-driven wind power system with PMSG (Permanent Magnetic Synchronous Generator). A simulation model has been built to demonstrate the maximum wind energy capture, DC voltage stability and decouping control of active and reactive power. In addition, the dynamic responses of system parameters during typical voltage sag and the role of dumping load at DC side have been tested. The simulation result shows that direct-driven wind power system has good capability of low voltage ride through.

The impact response of reinforced-concrete (RC) slabs covered with a sandy soil cushion layer was investigated using an outdoor rockfall impact test platform. Impact tests were carried out by releasing rockfalls with different weights from different heights to impact a combined structure. Test data included the acceleration duration curve of the rockfall, strain of the concrete slab at multiple measuring points, and midpoint displacement duration curve of the slab. The test results showed an exponential relationship between the impact force acting on the cushion layer surface and cushion layer thickness. An empirical formula was used to calculate the maximum penetration, and the result was in good agreement with the test value. In addition, the attenuation rate of the impact force acting on the cushion layer increased exponentially with the increase in the cushion layer thickness, and the peak impact force could be attenuated by approximately 70% at a thickness of 0.6 m. Finally, the failure process and failure modes of the RC slabs were investigated.

This paper presents a typical 450 m high rock slope in a highly jointed and fractured rock mass at Pubugou (PBG) hydropower station on the Dadu River. We established a set of multiphase field geological survey combined with GPS, inclinometers, and piezometer monitoring system to analyze the deformation and failure mechanism of rock slope. The results show that small-scale excavation in road construction disrupted the balance of the Pubugou rock slope (PBGRS), and several local retrogressive failures occurred at the toe. Monitoring data regarding surface and subsurface movements show that the PBGRS is stable as a whole. The deformation concentrated mainly in the loosened fractured zone, which was a feature with sliding-compression cracking. Highly loosened rock mass was the predominant factor affecting the stability of the PBGRS, while the role of reservoir water level fluctuation, though positive, was not significant. Overall, the PBGRS still has a high potential for further development, especially in the slope’s upper zone. To reinforce the slope, measurements mainly consist of the concrete frame combined with anchor cables constructed on the slope. In this study, the analysis was carried out of pre- and postreinforcement measure slope stability with numerical simulation, and safety factor increased from 1.09 to 1.21. This study’s findings have important implications to the analytical method and reinforcement design with geological settings like that of the PBGRS.