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2. PHD Thesis / Tesis PHD
3. Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

Title:	Resistance of high volume fly ash nano silica concrete tunnel exposed to high temperature and subjected to blast loading
Authors:	Mohamed Hamza Mussa (P77765)
Supervisor:	Azrul A. Mutalib, Dr.
Keywords:	Fly ash Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	9-Jun-2018
Description:	Terrorist activities have become one of the most influential events on tunnel structure safety which could cause a massive fire rises in a short time from 700 to 1200 oC as well as impact of the debris and shock wave. High volume fly ash nanosilica (HVFANS) concrete is considered as a new fireproof concrete developed via a previous study conducted in Universiti Kebangsaan Malaysia (UKM) laboratory by using 2.5 % of colloidal nanosilica with 52.5 % of fly ash. The new concrete was able to resist a fire reach up to 700 oC within a residual strength of 94.54 % from their original strength at room temperature. However, the blast resistant of HVFANS concrete tunnel exposed to high temperature has not been studied yet. Therefore, the main objective of this study is to determine the dynamic properties of HVFANS concrete exposed to elevated temperatures and assess damage levels of HVFANS concrete tunnel subjected to external explosion. Split Pressure Hopkinson Bar (SPHB) impact test was used to determine the dynamic properties of HVFANS concrete exposed to temperatures of 25, 400, and 700 oC and strain rates range between 30 to 100 s-1. At 700 oC, the results appeared that the static and dynamic (about 100 s-1) compressive strengths of HVFANS were recorded higher residual strengths of 85.13 and 77.59 % from their original strengths at room temperature, respectively. In similar conditions, the toughness, critical strain, and critical damage of HVFANS concrete showed superior behaviour by 77.62, 109.61, and 105.55 %, respectively. Moreover, the dynamic increase factor (DIF) expressions were successfully proposed to estimate the dynamic behaviour of HVFANS concrete exposed to temperatures of 25, 400, and 700 oC. An advanced Arbitrary Lagrangian Eulerian (ALE) technique available in LS-Dyna software was utilized to investigate the damage behaviour of an underground HVFANS box frame tunnel concrete subjected to a surface explosion of a sedan, van, small delivery truck (SDT), and container carrying 227, 454, 1,814, and 4536 kg, respectively, of TNT charge weight. The validation results indicated that the peak pressure values closely matched (0.94 % - 9.01 %) the predicted values of the technical design manual TM5-855-1, except for large distances (28.17 % - 36.36 %). Equations were derived to calculate the values of the peak pressure at large distances for each explosion case. Intensive parametric studies were conducted to propose level of damage for reinforced HVFANS tunnel affected by the variation of explosive magnitudes. The assessment of the damage levels using the single degree of freedom (SDOF) approach proved that the tunnel experienced low damage when the explosive charge is sedan and van with lining thickness above 500 mm at all investigated temperatures and burial depths. However, tunnel collapse occurred when the lining thickness less than 500 mm and subjected to an explosion of a container at investigated depths less than 6 m. The tunnel lining with a thickness and burial depth more than 750 mm and 6 m, respectively, appeared to be highly resistant to the any vehicle explosion at and exposing temperature up to 700 oC. The study has proven that HVFANS concrete could highly consider by designers to ensure the safety of an underground box tunnel when subjected to an incredible surface explosion and fire.,Ph.D.
Pages:	211
Call Number:	TA455.F55M867 2018 3 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Engineering and Built Environment / Fakulti Kejuruteraan dan Alam Bina

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