The Stability Evaluation And Elements Analysis Of Submarine Lanslides

There are many studies which are mainly aimed at the analysis of subaerial slope stability, but rarely involve the analysis of submarine slope. The limited understanding of submarine slope is in the scope of qualitative description, but few quantitative conclusion and theory are achieved, also present studies show a poor accuracy. As people’s activities gradually extend to the deep-ocean field and more offshore and costal engineerings are intented to construct, it becomes more and more important to develop the research of submarine slope stability and disaster prevention techniques. In order to achieve the quantitative analysis on the submarine slope stability, the numerical analysis and centrifugal model test are combined to evaluate the stability and calculate the scope of submarine landslides in this paper. Then some parametric studies are carried out to indicate the effects of key parameters as soil strength and soil density on submarine slope stability. This paper reads as follows:1) Strength reduction finite element method was adopted to evaluate the submarine slope stability by means of secondary development of safety factor searching automatically based on the numerical platform of ABAQUS software. Plenty of parametric studies were carried out to indicate the effects of soil properties on the submarine slope stability, such as submarine slope gradient, soil density, soil undrained strength, friction angle and so on. The relationship between the soil strength parameters and submarine slope gradient was provided to evalute the stability of submarine slope quantitatively. And this module of stability evaluation can be easily embedded into the aided decision-making system of submarine slope stability.2) A series of centrifugal modelling tests of marine landslide were carried out with the first drum centrifuge in China. Centrifugal tests were done respectively at under-water and no-water conditions. The pore pressure and mud sliding speed of soft clay with different water content are gotten at different centrifugal acceleration, in order to analyze the influence of water environment on the scope and sliding speed of marine landslide. At no-water condition，a pipe was embedded in the soil sample to simulate the impact of sliding mud on seabed pipelines. In order to discuss the effectiveness of the new alternative type of pore pressure transducer to DRUCK PDCR81series, precision detection and stability test were done at lg condition. Two tests had been conducted to check the performance of the new PPT at Ng condition, one is testing for static response, and the other is testing for dynamic response.3) Depth integrated model coupling smooth particle dynamic model ("SPH depth integrated model" for short) can simulate the whole propagation process of submarine slide. The dynamic process of the submarine slide can be showed through the establishment of the numerical model; The SPH depth integrated model was used in the numerical anylsis to predict the characteristics, such as the largerst runout distance, average flow velocity, deposition pattern, flow path and final volume; At the same time the influence of the soil strength parameters on the landslide process were discussed. In the future datas from modeling can be used as input in submarine disasters studies, where hazardous areas are defined and appropriate protective measures are designed.