中文摘要：

针对南海荔湾3-1气田管线穿过的海底峡谷区6个典型斜坡剖面,分别采用有限元强度折减法和极限平衡法开展斜坡稳定性分析,模型考虑了土层强度随深度的变化。计算结果对比表明,有限元强度折减法与极限平衡法分析结果一致,其中与Spencer法结果最接近,稳定系数相对误差小于3.5%。重力作用下各斜坡基本处于相对稳定状态,峡谷中下部土强度较低且坡度较高的局部区域接近临界状态,峡谷头部因坡度相对较小且土体强度相对较大,其斜坡稳定系数相对较高。地震水平加速度能够明显降低该区斜坡的稳定系数,且随着加速度值的增大滑动深度逐渐变大。当水平加速度达到0.2g时峡谷中下部区域大部分会发生滑动。海底地形坡度和土层强度是影响峡谷区斜坡稳定性的主要因素,且稳定系数与滑动面对局部坡度和强度分布较为敏感,合理的稳定性评价依赖于精确的地形数据与土层力学参数。

英文摘要：

The finite element strength reduction method and limit equilibrium method are used respectively for the slope stabilities of six typical profiles in the submarine canyon area where the submarine pipeline of Liwan3 - lgasfield is laid along its seabed. The soil strength characteristic of increase in depth is considered in the slope stabilities models. The comparison result shows that finite element strength reduction method and limit equilibrium method present consistent results. The stability factors obtained by the finite element strength reduction method are most closed to those of the Spencer method, with a relative error of less than 3. 5%.All the slopes are basically stable, although some local areas in the middle and lower parts of the canyon with low soil strength and high slope are close to the critical state. The slopes in the upper canyon area have relatively higher stability factors than those in the other areas. The horizontal seismic acceleration can reduce the slope stability factor greatly, and the sliding depth usually increases with the acceleration. When the horizontal acceleration is 0. 2g , most slopes in the middle and lower parts of the canyon would fail. The submarine slope angle and the soil strength are the mainly factors which control the slope stability in the canyon area. The stability factor and sliding depth are sensitive to the local slope angle and the strength distribution of the soil. A reasonable slope stability assessment result is dependent onthe accuracy of terrain data and soil mechanics parameters.