Slope monitoring optimization considering three-dimensional deformation and failure characteristics using the strength reduction method: A case study.

The potential deformation and failure of a slope with typical 3D shapes involve 3D characteristics, such that these factors cannot be simulated using 2D methods. If 3D characteristics are not considered in expressway slope monitoring, an excessive number of monitoring points may be arranged in the stable/safe part, whereas insufficient monitoring points may be arranged in the unstable/dangerous part. In this study, the 3D deformation and failure characteristics of the Lijiazhai slope of the Shicheng-Ji'an Expressway in Jiangxi Province, China were analyzed by 3D numerical simulations using the strength reduction method. The potential 3D slope surface displacement trends, initial position of failure, and maximum depth of potential slip surface were simulated and discussed. The deformation of Slope A was generally small. The slope ranging from the third platform to the slope top was located in Region I, where the deformation was approximately equal to zero. The deformation of Slope B was located in Region V, where the displacement generally was larger than 2 cm in the range from the first-third platforms to the slope top, and the deformation of the trailing edge exceeded 5 cm. The surface displacement monitoring points should be arranged in Region V. Monitoring was then optimized considering the 3D characteristics of the deformation and failure of a slope. Accordingly, surface and deep displacement monitoring networks were effectively arranged in the unstable/dangerous part of the slope. Results may be used as references for similar projects.

Experimental Study and Numerical Simulation of Overlying Layer Soil Failure Caused by Hydrate Decomposition.

During the exploration of hydrates or oil and gas exploitation through the hydrate layer, heat transfer causes hydrates to decompose. The gas and water generated by this decomposition increase the pressure of the gas in the decomposition zone, resulting in excessive pore pressure. The seepage of gas and water and the decomposition of hydrates lead to soil deformation, which may be caused by soil softening. This may lead to geological disasters, such as ocean landslides, seabed subsidence, and even gas explosions. The natural phenomena of soil eruption caused by hydrate decomposition currently include Siberian pits and Bermuda craters. From these two natural phenomena, climate change is considered to affect hydrate decomposition, causing ocean acidification and dissolved oxygen consumption, which may have more serious consequences than global warming alone. Therefore, it is extremely important to study how hydrate decomposition causes soil to erupt and release gas into the ocean and the atmosphere. This paper is primarily based on on-site data collected from the Siberian pit in the case of hydrate decomposition resulting in increased pore pressure, resulting in soil eruption. The relationship between the thickness of the upper cladding layer, the pressure causing the destruction of the upper cladding layer, and the destruction length of the upper cladding layer was obtained through numerical simulation.

Parasitic lasing suppression in high gain femtosecond petawatt Ti:sapphire amplifier.

New parasitic lasing suppression techniques are developed and high gain amplification is demonstrated in a petawatt level Ti:sapphire amplifier based on the chirped pulse amplification (CPA) scheme. Cladding the large aperture Ti:sapphire with refractive-index matched liquid doped with absorber suppresses the transverse lasing. The acousto-optic programmable dispersive filter (AOPDF) is used to realize side-lobe suppression in the temporal profile of the compressed pulse. The 800 nm laser output with peak power of 0.89 PW and pulse width of 29.0 fs is demonstrated.