Experimental Study On Dynamic Characteristics Of Explosion Response Of Calcareous Sand Foundation

At present,there are many fill islands and reefs in the south china sea,and there are civil-military projects with calcareous sand as foundation material.It is of great significance to study the dynamic response law of calcareous sand foundation explosion for engineering safety assessment and national defense needs.The dynamic characteristics of explosion response of calcareous sand foundation are studied by explosion test at outdoor site,and the stress development and explosion energy attenuation law of calcareous sand foundation under explosive load are analyzed.The main research contents and results are as follows:(1)The peak stress in calcareous sand foundation decreases rapidly with the increase of detonation center distance under explosive load;when the groundwater level is high,the fluid-solid coupling in the foundation is obvious,and the fluid-solid interactions have obvious dissipation effect on the explosion energy.(2)The limit Rs of radius of dangerous area and its calculation method are put forward in combination with the site test data and numerical calculation results.When the core distance is R ? Rs,the particles in calcareous sand foundation are broken seriously,the plastic energy dissipation increases rapidly,the stress attenuates rapidly and shows plastic properties.When R>Rs,the stress attenuation speed tends to be stable,and the foundation shows certain elastic properties.(3)The maximum stress peak in the whole immersion state is the largest under the explosive load,the stress peak in the non-underground water state is slightly smaller,and the stress peak in the semi-immersed state is significantly reduced;when the calcareous sand foundation is in a certain immersion state,it can attenuate the explosion more significantly and the stability is better.The theoretical calculation formula of the peak stress attenuation with the increase of detonation center distance is put forward in this paper,and the influence of groundwater level change on the stability of calcareous sand foundation is analyzed.The research results can provide theoretical basis for the engineering design,construction and prevention of explosion disaster of calcareous sand foundation,which has important political and economic significance and scientific value.