|
|
|
Title: RECOGNITION AND IDENTIFICATION OF LANDSLIDES
Accession Number: 00235699
Record Type: Component
Abstract: THE PROBLEMS OF RECOGNITION OF LANDSLIDES AND IDENTIFICATION OF LANDSLIDE TYPES ARE AS COMPLEX AS THE MATERIALS AND PROCESSES THAT CAUSE THEM. BECAUSE SO MANY VARIABLES ARE INVOLVED IN THE PRODUCATION OF LANDSLIDES, MANY TOOLS, THEORETICAL AND PRACTICAL, MUST BE USED IN RECOGNIZING AND CLASSIFYING THEM. SOME OF THE TECHNIQUES ARE DISCUSSED. THE APPROACHES ARE DIVIDED INTO TWO GROUP: (1) THE MEANS OF DETERMINING WHETHER OR NOT LANDSLIDE MOVE- MENTS HAVE ACTUALLY TAKEN PLACE OR ARE LIKELY TO DO SO IN THE FUTURE, AND (2) THE MEANS OF IDENTIFYING THE VARIOUS TYPES OF LANDSLIDES AND THEIR CONSTITUENT PARTS. EVIDENCE FOR ACTUAL OR POTENTIAL LANDSLIDES ARE DISCUSSED UNDER THE FOLLOWING CATEGORIES: ENVIRONMENTAL FACTORS, POTENTIAL SLIDES, EFFECTIVE PROPOSED CONSTRUCTION, ACTUAL SLIDES, SIGNIFICANCE OF CRACKS, AND HIDDEN SLIDES. AFTER IT HAS BEEN ESTABLISHED THAT LAND MOVEMENT HAS TAKEN PLACE, OR IS GOING ON, THE NEXT STEP IS TO IDENTIFY THE TYPE OF LANDSLIDE. ROCK FALLS AND SOIL FALLS ARE BEST RECOGNIZED BY THE ACCUMULATION OF MATERIAL THAT IS NOT DERIVED FROM THE UNDERLYING SLOPE AND THAT IS FOREIGN TO NORMAL PROCESSES OF EROSION. SLIDES, AS DISTINCT FROM FALLS, AND FLOWS, ARE CHARACTERIZED BY A HOST OF FEATURES THAT ARE OBSERVABLE AT THE SURFACE. THESE FEATURES ARE RELATED TO THE KIND OF MATERIAL IN WHICH THE SLIDE OCCURS, AS WELL AS TO THE AMOUNT AND DIRECTION OF MOTION. SLUMPS ARE CHARACTERIZED BY ROTATION OF THE BLOCK OR BLOCKS OF WHICH THEY ARE COMPOSED, WHEREAS BLOCK SLIDES ARE MARKED BY LATERAL SEPARATION WITH BUT LITTLE VERTICAL DISPLACEMENT AND BY VERTICAL RATHER THAN CONCAVE CRACKS. DRY FLOWS ARE COMMONLY COMPOSED OF UNIFORMLY SIZED SILT OR SAND. WET FLOWS OCCUR WHEN FINE-GRAIN SOILS WITH OR WITHOUT COARSER DEBRIS BECOME MOBILIZED BY AN EXCESS OF WATER. ROCK SLIDES CAN BE DISTINGUISHED FROM BLOCK SLIDES AND SLUMPS BY THE SIZE, SHAPE AND MAKEUP. ALL LANDSLIDE IN- VESTIGATIONS MUST START WITH RECOGNITION OF A DISTRESSED CONDITION IN THE NATURAL OR ARTIFICIAL SLOPE OR OF THE DANGERS THAT ARE INVOLVED IN READJUSTMENT OF THOSE STRESS CONDITIONS BY CONSTRUCTION WORK. THE EVIDENCE FOR THE STRESS CONDITIONS THAT MAY BE PRESENT, OR THAT MAY BE INDUCED, LIES CHIEFLY IN EVIDENCE OF MOVEMENTS, MINOR OR MAJOR, THAT HAVE ALREADY TAKEN PLACE OR OF GEOLOGIC, SOIL, AND HYDROLOGIC CONDITIONS THAT ARE LIKELY TO CAUSE MOVEMENT IN THE FUTURE.
Supplemental Notes: pp 48-68, 12 FIG, 1 TAB, 1 REF Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
Monograph Title: Monograph Accession #: 00234453
Authors: Ritchie, A MPublication Date: 1958
TRT Terms: Uncontrolled Terms: Subject Areas: Environment; Geotechnology; Highways; Hydraulics and Hydrology
Files: TRIS, TRB
Created Date: Aug 17 1970 12:00AM
More Articles from this Serial Issue: |
