1
Engineering Explosive Safety – Development of the Pseudo Underground Storage Structure (PUGSS)
C.C. Seah; Defence Science and Technology Agency; Singapore
W.T. Toh; Defence Science and Technology Agency; Singapore
H.S. Lim; Defence Science and Technology Agency; Singapore
Y. Kim; Naval Facilities Engineering and Expeditionary Warfare Center; United States
K. Hager; Naval Facilities Engineering and Expeditionary Warfare Center; United States
Keywords: Ammunition Storage; Earth Covered Magazine, Containment Structure, Explosive Safety, Blast
Abstract
There are many challenges when it comes to ensuring the safe storage of ammunitions in areas with high density
population, infrastructure development, or limited land availability in military installations. The scarcity of land
in Singapore has motivated the development of new technologies to overcome these challenges. In recent years,
DSTA had collaborated with NAVFAC EXWC to design and develop the Blast Resistant Wall (BRW) technology
and the Pseudo Underground Storage Structure (PUGSS) to reduce encumbered land for ammunition storage
when using conventional aboveground magazines. PUGSS is a specially engineered containment structure with
BRWs and a hardened roof that are capable of withstanding the internal explosion effects of ammunitions stored
within, and limit the damaging effects to the surrounding exposed sites (ES). This new type of engineered
containment structure has also raised the practical limit of the loading density or “charge weight to room volume
ratio” of the design of a reinforced concrete (RC) containment structure of maximum 2.4 kg/m
3
documented in
the US Department of Defense (DoD) Unified Facilities Criteria (UFC) 3-340-02 to 9.23 kg/m
3
. Starting with the
principles behind the BRW design, the paper delves into systematic process of developing the PUGSS storage
cell which design has been validated through an explosive test of a half-scale structure. The paper also presents
the possible applications of the BRW technology and PUGSS.
Introduction
With a land area of about 720km
2
and population of 5.7 million, Singapore is one of the most densely populated
country in the world. Besides catering land for residential, commercial and industrial purposes, there is also a need
to set aside land for military infrastructure and training.
Storing ammunition safely is one of the challenges that the Singapore Armed Forces (SAF) face. Large amount
of valuable land around each of the ammunition storage facilities has to be sterilised for explosive safety reasons.
Due to Singapore’s land scarcity, there is a strong impetus for the country to innovate in order to overcome the
land constraint with new technologies that can reduce hazards arising from the unlikely event of an accidental
explosions in ammunition storage facilities. One of these innovations is the development of engineered
containment structures for ammunition storage.
Engineered containment structures are buildings with hardened structural elements that are capable of
withstanding the internal explosion effects of ammunitions stored within, thus limiting the damaging effects of
the potential explosion site (PES) to the surrounding environment. Procedures for designing engineered reinforced
concrete (RC) containment structures are documented in the US Department of Defense (DoD) Unified Facilities
Criteria (UFC) 3-340-02 [1]. However, the practicality of the design of a RC containment structure is limited by
the loading density or “charge weight to room volume ratio” of maximum 2.4 kg/m
3
. This means that a large
structure is necessary to contain a small quantity of explosives which is not economically practical. To overcome
this limitation of conventional engineered containment structures, DSTA collaborated with NAVFAC EXWC to
develop the Singapore High Performance Magazine (HPM) [2] in the late 1990s using the database from
NAVFAC EXWC’s HPM and Non-Propagation Wall (NPW) test programmes. Ammunitions are stored in cells
in the Singapore HPM (see Figure 1), and has a maximum credible event (MCE) of 1 tonne, which is the storage
capacity of each cell. To push the design boundary of the Singapore HPM further, DSTA had in recent years
collaborated with NACFAC EXWC to design and develop the Blast Resistant Wall (BRW) technology and the
Pseudo Underground Storage Structure (PUGSS) which has a storage capacity of 5 tonnes per cell and loading
density of 9.23 kg/m
3
in each storage cell.
