Research On The Damage Effect Of Directly Buried Steel Pipe By Near Explosion In Soil

Effectively attacking weak links in the system and paralyzing core functions has become the main feature of air strikes in information warfare.This development trend has made the importance of urban underground lifeline projects to prevent air strikes more prominent.Steel pipes have been widely used in the protection design of underground directly buried cables in important projects.The study of the explosion damage effect of directly buried steel pipes is of great significance to the anti-explosion protection design of underground lifeline projects.In this paper,the short-range explosion failure test of directly buried through pipe optical cable in sand is designed and carried out,the failure mechanism of directly buried through pipe optical cable is analyzed,and a systematic study is carried out from the aspects of explosion failure effect,influencing factors and protection effect of steel pipe,the main research work and innovation results are as follows:1.A 60 mm diameter steel pipe with a diameter of 1.5 m buried in the soil was used as the research object to carry out a close-range explosion damage prototype test of 55 kg columnar TNT explosive sand.The test results show that when the explosion distance is 1.2 m,the communication function of this type of tubular optical cable is not affected when the steel pipe buckles obviously,and when the explosion distance is1 m,the steel pipe buckles significantly and is flattened,Optical cable communication interruption;the critical damage ratio of the pipe-through fiber optic cable is 0.263m·kg^-1/3～0.316 m·kg^-1/3.The test conducted tests on the impact pressure in the soil at different distances,the conductivity of the optical cable,and the bit error rate,and carried out the blast crater laser scanner test and the high-speed camera test.The shape and size lay the foundation for further research on the explosion damage effect.2.Using AUTODYN software,the numerical simulation analysis is carried out according to the test situation.The calculation results are in good agreement with the test results,which verifies the effectiveness of the numerical calculation;The calculation results show that the directly buried steel pipe will have overall bending and local sag deformation under short-range explosion load.The sag deformation is completed at the initial stage of deformation,and shows the characteristics of"four plastic hinges";The comprehensive analysis of the two results shows that the strong stamping effect of the inner wall of the pipe on the optical cable is the main reason for the functional damage of the directly buried through pipe optical cable when the serious depression deformation and damage occurs in the initial stage of steel pipe deformation.3.The sag deformation effect of directly buried steel pipe under short-range explosion load is studied.Through numerical calculation,the effects of diameter,wall thickness and material strength on the sag deformation speed of directly buried steel pipe under explosion impact load are further analyzed.The calculation results can provide reference for the selection of explosion protection engineering of directly buried steel pipe.4.The secondary development of AUTODYN is carried out.The numerical calculation is carried out for the explosion of cylindrical charge in soil with different buried depths.Based on the impulse,the contour distribution of explosion critical failure impulse in soil with different buried depths is calculated,and the distribution characteristics and range of critical failure line of directly buried through pipe optical cable are obtained,The research results can provide reference for the anti-explosion protection design of underground lifeline engineering under short-range explosion in soil.