DERIVATION OF STABILITY FORMULA OF GENTLE SLOPE AFFECTED BY TEMPORARY CONFINED WATER

In recent years,there have been a number of medium-large landslides in Ningzhen area. It is found that the structure of this kind of gentle slope is special: The lower part is coarse-grained soil with good permeability,while the shallow stratum is clay soil with poor permeability. And it is easy to form temporaryly confined water with high head,which causes large-scale intermittent creep under the action of its buoyancy. According to the structural characteristics of the gentle slope in Ningzhen area,this paper constructs a new hydrogeological model,then analyses the different part's stress characteristics under extreme heavy rainfall. And then this paper derives its stability coefficient formula by Janbu method. Finally,this paper calculates and compares the stability coefficient of the Paoma Mountain's landslide under different confined water heads. The results show that the confined water has a big difference in different part of gentle slope,which essentially explains the cause of sliding failure and the inaccuracy of the stability coefficient obtained by the traditional limit equilibrium method. This recognition provides a theoretical basis for the stability evaluation and landslide control of the Piedmont gentle slope in Ningzhen area.