Case Study of The Slope Stability Under Rapid Drawdown of Nam-Pong bank at BaanTahGae, Mueng District, Khon Kaen Province


  • Sorawich Thonsri นักศึกษา หลักสูตรวิศวกรรมศาสตรมหาบัณฑิต สาขาวิชาวิศวกรรมโยธา คณะวิศวกรรมศาสตร์ มหาวิทยาลัยขอนแก่น
  • Ratamanee Nuntasarn รองศาสตราจารย์ รัตมณี นันทสาร สาขาวิศวกรรมโยธา คณะวิศวกรรมศาสตร์ มหาวิทยาลัยขอนแก่น


Slope stability, Rapid drawdown, Finite element


This research studied the slope stability of the Nam-pong riverbank at Ban Tha Kae, Muang District, Khon Kaen Province, due to the rapid drawdown. The subsurface exploration was bored from the soil surface until a depth of 15 meters. The soil profile was divided into three layers; Lean Clay (CL), Clayey Sand (SC), and Silty Sand (SM). The consolidated undrained method determined an undisturbed clay sample's friction angle, cohesion, permeability coefficient, elastic modulus, and poison ratio from the triaxial test. The values ​​obtained from the test were analyzed by finite element method using Plaxis 2D program. In the analysis, the groundwater level was fixed, and the water level in the river was reduced by 25% from the groundwater level water level reach 75% of the groundwater level. The clay layer above groundwater was in an unsaturated condition. An unsaturated clay was analyzed as transition regime (the matric suction equal to 200 kPa) and residual regime (the matric suction equal to 300 kPa). Moreover, the specific date of reduction water level in the river was 60 days. Analysis shows that when water levels drop sharply at 75%, the safety ratio is the lowest. Soil movement was increase.


Kakaradee W. Study of Slope Stability Analysis by Comparing the Limit Equilibrium, Finite Element and Stress Based Method. 2013; 20(2):5-10.

Baba K, Bahi L, Ouadif L, Akhssas A. Slope stability evaluations by limit equilibrium and finite element methods applied to a railway in the Moroccan Rif. Open journal of civil engineering. 2012; 2(1):27.

Hammouri NA, Malkawi AIH, Yamin M. Stability analysis of slopes using the finite element method and limiting equilibrium approach. Bulletin of Engineering Geology and the Environment. (2008); 67(4):471.

Hough. “Unretained Earth Slope and Embankments”. Basic Soils Engineering. New York: Ronald Press Company.1957;1(1):7-8.

Navfac DM. Foundations and earth structures. Design manual.1982; 7(3):5-7.

Orr TLL. Effiect of Uncertainty in the Groundwater Level on Safety in Geotechnical Design. Proceedind of the Ninth European Confrence on Soil Mechanic and Foundation Enginerring. 1987; 3(31):4-8.

Pinyol NM, Alonso EE, Olivella S. Rapid drawdown in slopes and embankments. Water resources research.2008; 44(5):8-9.

Skempton AW. The pore-pressure coefficients A and B. Geotechnique.1954; 4(4):143-147.