Summary: | Slope structure, which is dominated by clayshale layers, wet field area and
spring as well as roadbed pile, requires practical and efficient solution. It also
highly influences the slope stability in relation to the base soil bearing force and
slope stability. The objective of this study is to identify the cause factors of the
movement of soil pile mass reinforced by bored pile during the construction
process, by calculating the soil bearing force as well as the pile slope ideal height
with consideration on the slope safety factor.
The slope stability analysis for Semarang � Solo toll road section II
Gedawang � Penggarong, was carried out by using the Geostudio, based on the
data of topography, investigation and field instruments. After the validation
results with horizontal direction movement pattern suitability of the slope were
identified, a simulation of various models due to the influence of reinforcement,
loading (traffic load) and ground water surface (rainy and dry season). The
simulation result of the horizontal movement was based on the inclinometers at 3
locations.
Results of this study indicated that the base soil bearing capacity of the
pile soil structure was 81,40 kN/m2. It is considered as in labile state in bearing
the load of the 24 meter height pile. The existing condition indicated landslide
potential within safe value of 0,894. This was influenced by the slope stratigraphy
which was dominated by clayshale layer and ground water surface fluctuation.
Pile soil mass reinforced by bored pile actually still moved within 0,215 m, with
safe value of 0,998. The result of horizontal movement traffic load was 0,298 with
safe value of 0,990. During the rainy season, water level increased in 4,0 m
average and reached weather clayshale layer with potential slide area and
horizontal deformation, which was 0,423 and decreased during the dry season in
8,0 m with horizontal deformation of 0,317.
Thus, the alternative of pile height decrease of 6,0 m contributed
significantly to the slope deformation and safe value from 0,990 to 1,213.
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