---

When geotechnical engineers are faced with cohesive clayey soils, the engineering properties of those soils may need to be

improved to make them suitable for construction. The aim of this paper is to study the effect of using lime, natural pozzolana or

a combination of both on the geotechnical characteristics of two cohesive soils. Lime or natural pozzolana were added to these

soils at ranges of 0-8% and 0-20%, respectively. In addition, combinations of lime-natural pozzolana were added at the same

ranges. Test specimens were subjected to compaction tests and shear tests. Specimens were cured for 1, 7, 28 and 90 days after

which they were tested for shear strength tests. Based on the experimental results, it was concluded that the combination limenatural

pozzolana showed an appreciable improvement of the cohesion and internal friction angle with curing period and

particularly at later ages for both soils.

---

Investigation of projectiles penetration phenomenon has been carried out in non-cohesive soil (Sand) targets under dry, saturated and compacted conditions. Analytical studies have been performed on the linear and non-linear soil models to obtain penetration depth formulae for ogival nose projectile and the results are verified by experimental studies. In present work, three ogival nose projectiles each having weight of 1.0 kg and nose angle of 15o, 30o and 45o are dropped from a height of 10.0 m in rectangular tank filled up by non-cohesive soil target. The rigid projectiles made an impact on a uniform target material at normal incidence with striking velocity of 14 m/s and proceeded to penetrate at rigid-body velocity. The models require geometrical parameters of the projectile types, velocity and target shear strength for the overall penetration depth of projectile. In addition, some parametric studies have been also carried out for academic and field interest.

---

Constitutive model for saturated cohesive soils based on the bounding surface plasticity notion with anisotropic hardening law is presented in the paper. The model predicts inelastic behaviour of overconsolidated cohesive soils. The projection centre is the only point in the stress space which represents elastic soil behaviour. Approximation of the plastic modulus within the preconsolidation domain is made using the radial mapping rule between a projection centre and a reflecting point on the bounding surface. The projection centre changes its position each time when stress path turns rapidly of more than 90°. The configuration of the elliptic bounding surface is governed by preconsolidation effective pressure p′c which depends on change of plastic both volumetric and deviatoric strain. Associated flow rule has been assumed in the formulation. Integration of constitutive relations is done according to forward Euler scheme with error control proposed by Sloan. The effectiveness of the proposed model is illustrated in both monotonic and cyclic loading in the homogeneous triaxial drained and undrained conditions.