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SUMMARY

ANALISA KESTABILAN LERENG AKIBAT VARIASI TINGGI MUKA AIR

TANAH (LOKASI DESA KEMUNING, JEMBER, JAWA TIMUR)

SLOPE STABILITY ANALYSIS BY WATER SURFACE LEVEL VARIATIONS (AT KEMUNING VILLAGE,JEMBER, EAST JAVA)

Created by NURHUDA, ANDIKA ZAIN

Subject : Stabilitas Lereng

Subject Alt : Soil stabilization

Keyword : : Proses pembasahan; Kadar air; Derajat kejenuhan; Tegangan air pori negatif tanah; Kohesi; Sudutgeser dalam; GEO-SLOPE; Stabilitas lereng

Description :Masalah stabilitas lereng mendapat perhatian meningkat akhir-akhir ini. Curah hujan yang tinggi merupakan penyebabterjadinya kelongsoran di beberapa Negara seperti Indonesia. Keruntuhan yang terjadi pada lereng alam dan lereng

buatan biasanya disebabkan oleh air hujan selama musim hujan. Mekanisme keruntuhan lereng diawali dengan

terjadinya peningkatan derajat kejenuhan atau kadar air tanah, akibatnya tegangan air pori negatif tanah menjadi turun,

sehingga tegangan efektif tanah akan berkurang. Hal ini menyebabkan kuat geser tanah berkurang hingga kondisi

keseimbangan lereng tidak dapat lagi dipertahankan. Selama ini pengaruh derajat kejenuhan yang berhubungan dengan

tegangan air pori negatif dan kuat geser tanah kurang diperhatikan dalam analisa stabilitas. Namun, untuk menganalisa

permasalahan lereng yang lebih baik, sebaliknya menggunakan atau menerapkan prinsip mekanika tanah tak jenuh.

Tujuan dari penelitian ini adalah untuk mengetahui pengaruh proses pembasahan terhadap parameter kuat geser.

Terutama, pengaruh perbedaan derajat kejenuhan dan kadar air terhadap kohesi (c ) dan sudut geser dalam ( )

pada tanah lanau berpasir daerah lereng desa kemuning, Jember-Jawa Timur yang mempunyai kadar air initial rata-rata

52,92 % dan derajat kejenuhan rata-rata 80,61 %. Proses pembasahan dilakukan dengan menambahkan kadar air benda

uji dari kondisi inisial sampai kondisi jenuh. Untuk mengukur tegangan air pori negatif, digunakan kertas filter

Waltman. Untuk menentukan parameter kuat geser, dilakukan percobaan geser langsung. Hasil percobaan menunjukan

bahwa, proses pembasahan mempengaruhi perubahan volume, tegangan air pori nagatif dan parameter kuat geser.

Proses pembasahan mengakibatkan meningkatnya kadar air dan derajat kejenuhan dan menurunkan tegangan air pori

negatif dan parameter kuat geser tanah. Mekanisme keruntuhan lereng menunjukan bahwa peningkatan derajat

kejenuhan menyebabkan penurunan tegangan air pori negatif tanah, sehingga tegangan efektif dan parameter kuat geser

menjadi turun sampai pada suatu titik dimana terjadi keruntuhan. Untuk mengetahui keruntuhan ini, maka dibuat

simulasi pembasahan pada lereng. Stabilitas lereng dihitung dengan bantuan program GEO-SLOPE dengan kemiringan

sudut 300,450,600,900 dan variasi muka air tanah yang berbeda-beda tiap kedalaman. Hasil analisa perhitunganmenunjukan bahwa derajat kejenuhan dan sudut kemiringan lereng mempunyai pengaruh yang signifikan terhadap

stabilitas lereng.

Description Alt:

Slope stability problems are receiving increasing attention in recent years. Rainfall seems to be the most common cause

of landslides in many countries such as Indonesia. Failures in both natural and cut slopes are usually brought about by

rainfall during the monsoon season. The mechanism of slope failure is that the increase of the degree of saturation or

water content that causes a reduction of matric suction in the unsaturated soil zone, resulting in a decrease of effective

stress. This in turn reduced the shear strength to a point where equilibrium can no longer sustained in a slope. In the past,

the effects of the degree of saturation that implies to be difference of soil suction associated to the shear strength of soil

were less explicitly considered in the conventional stability analysis. Therefore, to better analysis this type of slope

stability problem the principle of unsaturated soil mechanics should be applied. The objective of this present research is

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to investigate the influence of the wetting process to the shear strength parameter. In particular, emphasis is placed on

the effect of different degree of saturation or water content to the cohesion ( c ) and internal friction angle ( ) of

undisturbed silty sand soil from arjasa village in the East Java having average initial water content of 52,92% and

average degree of saturation of 80,61%. During the wetting process the soil specimens were gradually wetted from the

initial condition up to their saturation state. Waltman filter paper was used measure the soil suction. Direct shear test was

used to measure the soil strength. The experiment shows that the wetting process affect volume change, soil suction and

shear strength parameters. The wetting process resulted on the increase of water content and degree of saturation and on

the decrease of the soil suction and the shear strength parameters. The mechanism of slope failure is defined that the

increase of the degree of saturation that causes a reduction of matric in the unsaturated soil zone, resulting in a degreaseof effective stress and the shear strength to a point where equilibrium can no longer sustained in the slope. To develop a

better understanding of these failures, a parametric study was performed. Models of slope stability using GEO-SLOPE

program with slope angles 300,450,600,900 and different water surface. The result from the parametric study showed

that the degree of saturation together with the slope angle appeared to have the most significant effect on the stability of

the slope.

Contributor : Dr. Ir. Ria Asih Aryani Soemitro, M.Eng

Date Create : 01/01/2010

Type : Text

Format : pdf

Language : Indonesian

Identifier : ITS-Undergraduate-3100010038923

Collection : 3100010038923

Call Number : RSS 624.151 363 Nur a

Source : Undergraduate Thesis, Civil Engineering, RSS 624.151 363 Nur a, 2010

COverage : ITS Community

Right : Copyright @2010 by ITS Library. This publication is protected by copyright and per obtainedfrom the ITS Library prior to any prohibited reproduction, storage in a re transmission in any formor by any means, electronic, mechanical, photocopying, reco For information regardingpermission(s), write to ITS Library

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Thank You,

Nur Hasan ( hassane@its.ac.id )

Supervisor

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