突发型黄土滑坡的临界水位研究——以甘肃黑方台黄土滑坡为例

Critical water level of abrupt loess landslides:a case study in Heifangtai,Gansu Province

甘肃省黑方台黄土滑坡的现场调查表明,地下水位的上升会导致突发型黄土滑坡发生;典型滑坡水位和变形的同步监测,证实地下水位上升到一定限度后会引起滑坡的变形破坏。为进一步揭示水位对土体破坏的影响,采用三轴常偏应力排水剪试验研究了孔隙水压力逐级增加过程中土体的破坏过程。结果表明,孔隙水压力达到轴向应力26%时会引起土体变形的突然增长并破坏,对应了黑方台地下水位占黄土厚度比例为0.4时会引起坡体失稳,并通过现场调查滑坡水位和黄土厚度验证了试验结果。结合试验和调查,以水位比例建立了这类滑坡的判识方法。

The field investigation of Heifangtai loess landslides in Gansu Province shows that the rise of groundwater level may lead to abrupt loess landslides.Based on the synchronous monitoring of water level and deformation of typical landslide,it is confirmed that when the groundwater level rises to a certain extent,it will cause deformation and failure of landslides.In order to further reveal the influence of water level on soil failure,the failure process of soil in the process of gradual increase of pore water pressure is studied by triaxial normal deviatoric stress drainage shear test.The results show that the pore water pressure can cause the sudden increase and destruction of the soil deformation when the axial stress is 26%,which is verified by the field investigation of the landslide water level and the thickness of the Loess by the ground water level of Heifangtai which accounts for the thickness ratio of 0.4 of the loess.Combined with the test and investigation,the identification method of such landslide is established based on the water level ratio.