Strain softening of soil under cyclic loading

a case study of Khlong Pa Bon Dam

Name: Panthi, Kobid

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

Classification :.LCCS: TA710.T35

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

LCSH: Soil mechanics -- Khlong Pa Bon Dam

Abstract: On June 27, 2014 slope movement was observed in upstream side of Khlong Pa Bon Dam, Thailand. The movement did not have any major catastrophic impact on the dam structure at the time of movement but raised a very important question regarding the movement of the slope after 10 years of operation. It was observed that the dam had undergone a greatest differential drawdown in its operational history in the year 2014 and was hypothesized as the major cause of movement. The investigation was carried out using site investigation, laboratory tests and numerical modeling. The failure plane was determined from bore hole investigation and resistivity test. The residual strength of the soil sample was determined using the reversal direct shear test as the property of soil was found to be near the residual state at the time of failure. Rapid drawdown analysis was conducted in failure zone to find out that the movement did not occur solely due to rapid drawdown of water. In addition, slope stability analysis was also conducted in both failure zone and zone where it did not fail to compare the behavior of soil with drawdown of water using various methods. From the back analysis, it was found that the shear strength of embankment slope was near its residual value during the time of failure and hence the numerical analysis was further carried out using MCC (Modified Cam Clay) and MC (Mohr Coulomb) Model to compare the strain softening behavior of the slope. MC model showed the increase in volumetric and shear strain with the drawdown of water level but the volumetric strain reached its original value after a one complete cycle while the accumulation of shear strain was observed. Likewise, both volumetric and shear strain accumulation was observed using MCC model. It was found that the cyclic movement of water i.e. reservoir filling and drawdown was the cause of strain accumulation. The strain was accumulating each year with each drawdown cycle and failure was triggered by sudden drawdown of water in 2014. On the basis of this investigation, the design standards have also been proposed to prevent the upstream slope failure from cyclic drawdown of water in future.

Kasetsart University. Office of the University Library

Address: Bangkok

Email: tdckulib@ku.ac.th

Name: Suttisak Soralump

Role: Thesis Advisor

Name: Suriyon Prempramote

Role: Thesis CO-Advisor

Created: 2019

Modified: 2025-08-03

Issued: 2025-08-03

วิทยานิพนธ์/Thesis

application/pdf

URL: https://www.lib.ku.ac.th/KUthesis/2562/kobid-pan-all.pdf

CallNumber: TA710.T35 .P26

eng

Spatial: Khlong Pa Bon Dam

DegreeName: Master of Engineering

Level: Master's Degree

Descipline: Civil Engineering

Grantor: Kasetsart University

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