<p>For a jet to effectively penetrate a soil-covered target, the depth of penetration (DOP) into the soil must exceed a critical threshold, while the cavity diameter produced by the precursor shaped charge of a tandem warhead should be large enough to allow the unimpeded passage of the main projectile. In light of the prevalent application of protective structures with overburden layers, this study examines the penetration behavior of shaped charge jets into soil targets. Additionally, the impact of soil moisture content—considering seasonal variations—on jet penetration performance is investigated. The analysis addresses the roles of shock waves and compressibility during penetration, proposes a novel four-stage penetration process, and formulates an axial penetration equation. Based on this framework, a jet penetration model for soil targets is developed by incorporating the HELD cavity growth model. Four experimental tests were carried out in which shaped charge jets penetrated soil with different moisture contents. The results indicate that the proposed model provides accurate predictions for both radial cavity growth and DOP, showing good agreement with experimental data. Furthermore, it is observed that radial cavity dimensions increase markedly with rising moisture content, whereas axial penetration depth remains largely unaffected.</p> Graphical abstract <p></p>