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http://dx.doi.org/10.17576/jsm-2019-4811-22
Modelling Viscous
Behaviour of Clayey Geomaterials using Single Mechanical-Analogue Model
(Pemodelan Sifat
Kelikatan Bahan Geologi Berlumpur menggunakan Model Analog Mekanik Tunggal)
NOR SHAHIDAH MOHD NAZER*
Centre
for Earth Sciences and Environment, Faculty of Science and Technology,
Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor Darul
Ehsan, Malaysia
Diserahkan: 4
April 2019/Diterima: 15 Ogos 2019
ABSTRACT
The design of sustainable
early warning systems for landslide prone areas requires deep understanding
of the kinematic of landslides with emphasis on the evolution of
its movement. This is controlled by many factors, and creep is a
major one. Creep is perceptively slow land sliding process where
the movement is nearly imperceptible and occurring at a rate of
millimetres (mm) per year. This article reports the results of investigations
of the viscous shear behaviour of clayey geo-materials, in particular
creep and relaxation, which were carried out using a direct shear
box. The viscous behaviour was investigated by either measuring
the decay in shear stress at constant relative horizontal displacement
(stress relaxation test) or by measuring the evolution of relative
horizontal displacements at constant shear stress (creep test).
Initially, 3 elements model of spring and dashpots combination was
proposed to simulate the viscous behaviour of clayey geo-materials.
However, because the loading system of direct shear box is not stiff
and is showing some creep/relaxation interplay during viscous test,
effect from the compliance system of the shear box must be carefully
considered when formulating mechanical models for saturated and
unsaturated slope kinematics. Another elastic element was added
to the 3 elements model to address the issue of deforming loading
system. The proposed modified model capable of simulating creep
and stress relaxation response using a single set of parameters
and thus, allowing creep response to be inferred from stress relaxation
response by means of direct shear test in lab.
Keywords: Clayey
geomaterials; mechanical-analogue model; modelling; viscous
ABSTRAK
Penciptaan Sistem
Amaran Awal untuk kawasan dedahan tanah runtuh memerlukan pemahaman mendalam
terhadap kinematik tanah runtuh dengan penekanan terhadap evolusi
pergerakannya. Ianya dikawal oleh banyak faktor, dan rayapan adalah yang paling
utama. Rayapan adalah proses pergerakan tanah secara perlahan kerana pergerakan
adalah hampir tidak dapat dikesan dan berlaku pada kadar milimeter (mm) setiap
tahun. Kertas ini melaporkan hasil kajian sifat kelikatan ricihan bahan
geo-lempung, khususnya rayapan dan santaian, dilakukan menggunakan kotak ricih
terus. Sifat kelikatan dikaji melalui pengukuran pereputan tekanan ricih pada
anjakan mendatar seragam relatif (ujian santaian tekanan) atau melalui
pengukuran evolusi anjakan mendatar relatif pada tekanan ricihan seragam (ujian
rayapan). Asalannya, model 3 unsur yang terdiri daripada gabungan spring dan
peredam telah dicadangkan untuk mensimulasi sifat kelikatan bahan geo-lempung.
Walau bagaimanapun, memandangkan sistem bebanan kotak ricih terus tidak pegun
dan menunjukkan sedikit saling rayapan/santaian semasa ujian kelikatan, kesan daripada
sistem pematuhan kotak ricih terus mestilah diambil kira dengan waspada sewaktu
merumuskan model mekanik bagi kinematik cerun tepu dan tidak tepu. unsur
elastik tambahan telah ditambah kepada model 3 unsur untuk mengatasi masalah
kebolehubahan bentuk sistem bebanan. Model terubah suai yang dicadangkan
berkebolehan mensimulasi tindak balas rayapan dan tekanan santaian menggunakan
set parameter tunggal dan maka dengan itu, membolehkan tindak balas rayapan
dijana daripada tekanan santaian melalui ujian kotak ricih terus di makmal.
Kata kunci: Bahan
geologi berlumpur; kelikatan; model analog mekanikal; pemodelan
RUJUKAN
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*Pengarang untuk surat-menyurat; email: shahidahnazer@ukm.edu.my
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