Landslide Part 2

Landslide Investigation

Moving masses have different variables that affecting the displacement. This variables are controlled by geology of the site, climatic conditions, human impact, natural impact, erosion and groundwater regime. Collecting and determining the parameters of these variables is highly important for analyzing of the moving body correctly. Even obtaining parameters correctly, additional measures required for uncertainties (measured by FoS) to achieve permanent stabilization.

The first consideration should be understood the cause of the landslide, then obtain sufficient data to model it and accordingly determine the remediation options that best suit the obtained situation.

Correct and efficient rehabilitation method can be obtained only by determining cause of displacement, type and geotechnical parameters of the moving mass, boundaries of the moving mass, shear strength parameters of the failure surface and groundwater regime of the area. Therefore landslide investigations require planned and detailed studies to determine root & cause of the mass movement.

I have sorted investigations for landslide step by step in 8 main topics;

1. Regional Geology
2. Site Geology & Geomorphology
3. Site Investigation Technic & Location
4. Site Investigation Data & Laboratory Test Schedules
5. Instrumentation Data
6. Laboratory Test Results
7. Modelling Landslide & Determining Geotechnical Parameters
8. Determining rehabilitation Methods

1. Regional Geology

Assessment of the regional geology begins with researching the available information about wider area of concentrated location. Typical and important sources of information are ; topographical maps, aerial & satellite photography, geological & geomorphological maps-reports and papers and field trip notes etc.  

Based on the known geology and geomorphology selected locations in the area is investigated detailed to further the understanding of the overall setting of the site. Particularly focus on factors such as stratigraphy, low strength soil and rock units, groundwater system, weathering patterns, tectonic deformation, other landslides etc. 

In these factors specially other landslides give you basis information. Comparing the study area with previously failed masses will be guided you about failure boundaries of the landslide and type of failure.

All collected information about regional geology will be used in step 2 & 3.

2. Site Geology & Geomorphology

Assessment of local geology is important to localize the site in a regional geological setting thus, underlying geological conditions and expected ground model can be estimated. This estimations are useful in determining ground investigation points. 

Determining geomorphology is important in mapping the boundaries and surface features of a landslide to understand the landslide mechanism. This is the most important step before decide on ground investigation methods and locations. In this step preparing a geomorphological mapping will be provided a vision to see big picture and to determine accurate position of ground investigation points. 

Geomorphology Map Drawn by Me to Understand the Small Scale Debris Slide

Visit Landslide page to read unified article series.