Design of Pre-Weakening and Evaluation of Structural Safety for Explosive Demolition of Concrete Silo

Recently the demand for demolition of unnecessary cylindrical silo structure is increasing due to the deterioration and malfunctional conditions and the issue of demolition is in the limelight. To minimize environmental hazards caused during the process of demolition, the explosive demolition method has been applied increasingly. The concrete silo structure is often built by the slip-form method which is a continuous concrete casting operation. As a result, the structure does not have expansion joints or other structural weaknesses that can be used to assist in the demolition process. This study presents the pre-weakening of explosive demolition of the cylindrical concrete silo structure by overturning method. Pre-weakening for the explosive demolition of the structure is usually conducted based on the field experience without technical guideline for the pre-weakening procedure. Hence, there always exist safety-related concerns. To demolish the structure by blast effectively and safely, rational approach to the pre-weakening and evaluation method of the load carrying capacity of the pre-weakened structure should be established. To do this, mechanical properties of concrete are estimated by experiment prior to structural analysis. Based on the result of investigation, design or operation methods of pre-weakening for the blast demolition are discussed.