Centrifuge modeling of dynamic response of underground concrete silo against adjacent buried explosion loads

Abstract

The underground silo has a wide range of applications in both civil and military engineering, and is vulnerable to intense loadings such as explosion in some special service scenarios. This study focuses on the dynamic response of underground concrete silo against adjacent buried explosion loads. Three groups of centrifuge model tests of buried explosion near the silo structure in dry sand are designed and conducted. The characteristic parameters of excavated cratering, blast loadings, and structure vibration are recorded in the tests, and the effect of charge DoB (depth of burial) and stand-off distance are analyzed. The distribution pattern of blast loadings on the silo front is investigated, and a general formula is derived to predict the peak blast overpressure along the silo front based on dimensional analysis and test results. The blast-induced structure vibration inside the silo is monitored, and the mechanism of interior structure motion under external explosion loadings is discussed. The time-frequency analysis of the interior acceleration response is conducted using the HHT (Hilbert-Huang Transform) method. The silo exhibits a high-frequency forced vibration pattern within the positive overpressure duration, whereafter falls into the low-frequency sinusoidal free vibration stage. The tolerance and fragility assessment of personnel and accessory equipment inside the silo is further performed based on the peak acceleration and shock response spectrum criteria. The results show that despite no apparent damage being observed on the concrete silo under the explosion conditions in this study (TNT equivalent of 1200 kg and stand-off distance close to 5.3 m in prototype), the blast-induced structure vibration would pose a significant threat to the interior personnel and precision instruments such as computers and communication devices. The research findings can benefit the prediction of blast loadings and dynamic response of concrete silos subjected to external explosion, and provide a robust experimental basis for underground protective engineering design.