PENGARUH KANDUNGAN LEMPUNG DAN KADAR AIR TERHADAP COHESI DAN PHI TANAH LANAU BERLEMPUNG

Abstract

ABSTRACT
In this year, landslide disaster such as embankment slide, bank
slide, or buried of soil (trash) often occurs. All of them begin with a
simple problem, that is infiltration of rain water (or other) into soil causing
the decrease of shear strength, finally passed the limit of landslide safety
factor F, so landslide occurs. The research tries to know the behavior of
clayey-mud soil with several ratio of clay content and several water
content ratio to find out how much clay content and water content (w)
may induce soil collapse.
This experiment research was conducted in the soil laboratory
UNY using clayey-mud soil from Klaten which has been conditioned in
several clay content (00/0-400/0) and water content w (20%-30%) and
then direct shear tests were applied. The product of this experiment
were: cohesion (c), internal soil shear angle, phi (<p), and safety factor of
landslide (F).
This research has resulted: (1) For pure mud soil, until 25% water
content, would decrease of cohesion (interlocking), but >25% water
content,interlocking (cohesion) would constant. The maximum cohesion
(interlocking)(0.09 kg/cm2) reaches at 20% of water content (2) For
pure mud soil, increasing of water content until 30% would increase of <p
and F. The maximum <p value (41.8°) occur at 30% water content (at 0%
clay content); (3) For clayey-mud soil, increasing of water content
causes increasing or constant of cohesion. The cohesion would increase
if 10%-20% clay content. The c value until 0.0665 kg/cm2 at 30% water
content (at 100/0 clay content); and (4) For clayey-mud soil, increasing of
water content (until 25%) would increase of <p and F. The <p value could
until 40.9° at w=25% (at 10% clay content). If w>25%, the value of <p
and F would decrease. The <p value until 7.7° at w=300/0 (at 40% clay
content).
Keywords: mud. clay, soil, water content, cohesion,
landslide.