Theoretical Analysis And Experimental Verification Of Penetration Process Of Torpedo Anchor

Penetration depth of torpedo anchor is affected by multiple parameters and has not been fully studied.Therefore,it can confirm the influence parameters of penetration depth reasonably by the study of penetration process of torpedo anchor through the experiment and theoretical analysis,which has theoretical and practical engineering significance in engineering application.Based on the theoretical analysis,this paper studied the penetration process of torpedo anchor in detail by small-scale model anchor penetration test.Main work as following:(1).Based on theoretical analysis,the torpedo penetration equation is established.This paper established dynamic response equation employing Tresca yield criterion to describe the constitutive relations based on the spherical cavity-expansion theory by governing equation in plastic region and elastic region of soil and derived the tip resistance of the anchor;Assuming the anchor penetrating into soil vertically and the soil had only horizontal displacement,which could be considered as a plane strain problem.Under the condition,penetration equation was established according to Newton's Second Law with consideration of the tip resistance and frictional resistance.Moreover,the numerical solution was obtained.(2).Experimental study of small-scale model anchor penetration into saturated sand.The test of finless model anchor penetration into saturated sand was carried out by self-made launch device.Acceleration time-history signal and final penetration depth were measured under the conditions of different relative densities of sand and different initial velocity.It indicated that relative densities and initial velocity had great impact on the penetration depth.(3).Penetration equation was verify by experiment.The measured curves of velocity vs.depth of small-scale model anchor agreed well with theoretical solution,while a little deviation existed in the curves of acceleration vs.depth.Furthermore,torpedo anchor penetration test in centrifuge was verified as well.The calculation results of penetration depth were essentially the same as experimental results.(4).To study typical type of torpedo anchor,penetration equations of 4-fin anchor were established based on theoretical analysis.The process of the anchor penetrating into two different layer soil was analysed by numerical calculation.Effects of shape of tip,length-width ratio of fins and initial velocity on penetration depth were investigated,respectively.Change rules of tip resistance and frictional resistance as well as their energy were discussed.