Although; over-saturation of pore-water has been known as potential stress agent, there hasn't been attention to subgrades behavior under extreme dry state. For improved design and construction to mitigate cracks, the two extreme states were considered at Cargo Airport site around fractured Abakaliki anticlinoria, Nigeria. Dynamic tests (remote sensing, electrical-resistivity) and static tests (Atterberg limit, Standard Penetration, Dynamic Cone Penetrometer) produced results that formed basis of modeled solutions, and revealed potential shear planes. Such planes typically reflected low friction angle between 11 degrees and 13 degrees, as well as cohesion ranging from 13 to 23 kPa; indicating isolated silty clay with Plasticity index (PI) = 1.5, and verified through stress-curves behavior in response to pore-pressure status. Such responses created various spaces between the curves. Comparing the space relations in ratios showed novel mathematical demonstration for pavements stability prediction.

Unlike the mechanism of earthquake or ocean wave loads, the dynamic response characteristics of the liquefiable strata under the influence of the vibrating loads of the cutter-head of shield tunneling in special strata are unique. This paper investigates the significance of the dynamic interaction between a large-diameter shield tunnel and the liquefiable saturated silty sand strata during the process of liquefaction-induced under the vibrating loads of a shield cutter-head. The coupled effective stress model-which is the Davidenkov nonlinear hysteresis model based on equivalent shear strain algorithm and irregular loading and unloading criterion combined with an incremental excess pore water pressure (EPWP) model coupled with shear-volume strain-is used to describe the stiffness degradation and characteristics of the rising EPWP during the process of liquefaction-induced. The material parameters of silty sand corresponding to the coupled effective stress model are calibrated based on the experimental data of samples obtained from dynamic triaxial shear test under cyclic loads. The numerical results indicate that the acceleration, the EPWP ratio (EPWPR), and displacement distribution of the liquefiable strata all match the influenced range of the vibrating loads, the influence of relative density and thickness of the sand strata. It is concluded that the vibrating loads of the shield machine tunneling in the silty sand-rock composite strata is unfavorable for the safety of the strata and tunnel, and grouting reinforcement should be carried out in a timely manner during construction.