基于NMR的库区滑坡三维稳定性数值模拟

Numerical Simulation of the 3D Landslide Stability in Three Gorges Area Based on NMR

传统的勘探、测试手段,难以获取可靠的滑坡岩土体水文参数,直接影响滑坡研究的建模、评价工作.应用核磁共振找水方法并结合其他方法建立滑坡三维地质模型,并提出基于NMR技术的库区滑坡稳定性研究思路.以赵树岭滑坡进行测试,获取了岩土体的水文地质参数数据,确定出该滑坡具有两层地下水,上部潜水含水层,下部微承压含水层;具有两层滑面.该技术的分析结果与钻孔数据吻合较好,可为建立符合实际的滑坡模型提供可靠依据.利用自编渗流-应力耦合有限元程序和ANSYS进行了145m、175m及175m降至145m滑坡的稳定性模拟.结果表明:145m及175m水位,该滑坡整体处于稳定状态,前缘随水位抬升局部破坏范围扩大;175m降到145m时,坡整体稳定性接近极限状态.且滑坡后缘局部位置出现小规模变形破坏的可能.

Reliable hydrological parameters of the rock and soil in a landslide are difficult to obtain using traditional investigative and testing methodology. This affects the quality of landslide modelling and evaluation. Based on the NMR （nuclear magnetism resonance） method of water seeking combined with some other investigation methods, a 3D landslide model was established. The method for studying the landslide stability in the Three Gorges was presented. The Zhaoshuling landslide in the Three Gorges Reservoir area was chosen to determine the accuracy of the 3D modelling. The hydrological parameters of the rock and soil were obtained by NMR and from a borehole. Two aquifers were determined： the upper one is an unconfined aquifer; and two sliding zones were found. The result from NMR analysis was identical with the data obtained from the borehole. This result could supply a reliable basis for landslide modelling which conforms to actual landslide conditions. Using the FEM program to consider the interaction between seepage and stress and ANSYS, the stability of the landslide was simulated with a water level under 145 m, at 175 m and from 175 m falling to 145 m. The results show that the landslide is still in a stable state at a water level of 145 m and 175 m. The unstable area in the front region of the landslide enlarges as the water level rises. When the water level falls from 175 m to 145 m, the landslide is in a state of limited equilibrium and local deformation and damage on the posterior border of the landslide is likely to occur.