การศึกษาปริมาณน้ำฝนวิกฤตเพื่อการเตือนภัยลาดดินพิบัติ : กรณีศึกษา ต.คลองทราย อ.นาทวี จ.สงขลา

Abstract

In Thailand, rainfall-triggered landslides have caused economic difficulties and even loss of life. This study focuses on a landslide prone area of Songkhla province. A selected study area was Baan Koklukmee, Klongsai subdistrict, Nathawi district, Songkhla province, where a landslide took place on January 1", , 2012. Ground surveying, field testing, and laboratory testing were conducted to collect necessary data for development of a numerical landslide model. Seepage analysis of rainwater through the slope was conducted using finite element method. Slope stability analysis was conducted to assess the factor of safety of the failed slope using Bishop's simplified method. Study results show that the landslide site was 197.71 m long, 0.8 - 1.2 m thick with approximate inclined angle of 28 degrees. Simulation results of the actual rainfall event from December 29* , 2011 to January 2", 2012 indicate that while the critical cumulative rainfall exceeded 310 mm, the corresponding factor safety of the slope was less than unity and landslide occurred. The simulation results can truly be depicted the actual landslide, thus the developed landslide model can be effectively used for computing the critical cumulative rainfalls for several landslides and rainfall conditions. Accordingly, a series of critical cumulative rainfall graphs and maps were constructed. They can be used for landslide warning purposes in the study area.