Ground movement triggered by dynamic loads has been investigated in South-eastern Nigeria, a typical area of the humid tropical region underlain by lateritic soils. The study was conducted using varying weights of dynamite charge (explosive) placed at varying distances and depths from a chosen monitoring station. The dynamite explosions triggered off transient-type ground motions. These were transmitted away from the shot points through the thick overburden. The attenuation of these vibrations in the overburden soil and surrounding earth materials was closely monitored. The results show that the vibration propagation is typified by a fairly high attenuation coefficient - evidenced by a rapid decrease in velocity amplitude with distance from the shot point. The bulk of the peak values of velocity amplitude recorded during the monitoring fell within the zone of structural safety when compared with internationally accepted damage criteria for vibrations. In terms of human response criteria, however, the peak values indicate that the vibration level would attract complaints from occupants of property located within 500 m from the shot point, particularly if the shooting was carried out in the vicinity of a built-up area. The findings have been used to formulate a preliminary configuration that could be adopted during activities which involve the artificial generation of ground motions and vibrations, particularly those associated with construction work, and the operation of seismic crews engaged in oil and gas exploration. Furthermore, the minimum safe shooting distances determined for various depth and charge combinations revealed that for a given weight of explosive it may be safer to shoot at a smaller than a greater depth.

Artificial sensitive clay can be prepared in the laboratory for physical modeling and one of the recipes is using a small amount of cement (2 to 5%) with controlled initial water content and hardening period. Use of artificially cemented clay requires the knowledge regarding its compressibility and shear strength. In this paper characteristics of compressibility and strength loss of weakly cemented clays are investigated for both artificially cemented high plasticity San Francisco Bay Mud and low plasticity Yolo Loam. Destructuration and softening behavior for weakly cemented sensitive clays are demonstrated and discussed through multiple series of incremental (ICL) and constant rate of (CRS) consolidation tests, unconfined uniaxial compression tests (UC), and monotonic, cyclic, postcyclic monotonic direct simple shear (DSS) tests. As a result, the post-peak strain softening and cyclic strength loss are proven to be remarkable for weakly cement treated clays. The results would be beneficial to the study of physical modeling for sensitive clays in that artificially cemented clay can be successfully constructed in a reproductive manner with satisfying desired shear strength and sensitivity. Test data are also contributable to provide references for constitutive modelers in pursuit of structured clay simulation.