In-situ and laboratory determination of small-strain stiffness-suction-moisture relationships and its application

Name: Avishek Shrestha

LCSH: Kasetsart University -- Theses. M.Eng. (Civil Engineering) 2019

Classification :.LCCS: TA418.64

LCSH: Kasetsart University. -- Department of Civil Engineering -- Theses

LCSH: Strains and stresses

LCSH: Stress-strain curves

LCSH: Bending stresses

LCSH: Soil moisture -- Measurement

LCSH: Moisture -- Measurement

Abstract: Small-strain stiffness (G0) is an important parameter that governs the engineering behaviour of the soil. Determining its relationship with suction, which is present in most of the geotechnical structure lying above the groundwater table, is important as the behaviour of the structure is influenced by these properties especially in the post-compaction stage. This study aims at finding the relationship between G0, suction and moisture content both under laboratory and in-situ conditions. Two sites from Kanchanaburi province of Thailand comprising of mechanically stabilized earthen (MSE) wall and a natural slope was chosen for the study along with a clay dyke located at Asian Institute of Technology, Bangkok. As for the investigation of the relationship under laboratory condition, free-free resonant frequency (FFR) test was conducted on recompacted soil sample collected from those sites. Similarly, spectral analysis of surface waves (SASW) was done in-situ at different time periods to study the change in G0 relative to suction which was measured in the field through various instrumentations. Soil water retention curve (SWRC) was determined in the laboratory to relate the suction measured in the field with the moisture content. Through the FFR test, in the tested suction range, G0 and suction were found to be positively correlated for all the soil sample, though the rate of increase in G0 with suction varied. Through the SASW test, it was found that the effect of suction on G0 was dominant only for the initial depths of about 1 m, after which the effect of overburden pressure was more pronounced. Also, for the same suction values, G0 obtained from SASW test on an intact ground was higher than that from FFR test because of the presence of confining pressure. In addition, it was found that the stiffness of the MSE wall which was reinforced with geosynthetics and geotextiles remained fairly constant for different time periods, whereas in natural slope stiffness varied proportionately with suction for about a depth of 1m. Intriguing results were found through the series of SASW tests on clay dyke as the presumption that G0 increased with suction was not valid and it was later explained by the presence of shrinkage cracks. As an application of G0 and suction relationship, SASW along with suction measuring sensors has been proposed as a method to determine the shrinkage cracks developing underneath the soil which are not visible. The crack depth measured in the field was then modelled using a semi-empirical procedure which can be used to predict crack depth relative to suction.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Apiniti Jotisankasa

Role: Thesis Advisor

Name: Susit Chaiprakaikeow

Role: Thesis CO-Advisor

Name: Suttisak Soralump

Role: Thesis CO-Advisor

Created: 2019

Modified: 2025-07-03

Issued: 2025-07-03

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2562/avishek-shr-all.pdf

CallNumber: TA418.64 .A94

eng

DegreeName: Master of Engineering

Level: Master's Degree

Descipline: Civil Engineering

Grantor: Kasetsart University

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