The generation of excess pore water pressure (EPWP) and liquefaction characteristic of soils under seismic loading have long been topics of interest and ongoing discussion. Based on the structural state exhibited in the liquefaction process, the mechanical property of saturated coral sand is divided into solid, pseudo-fluid, and liquid phases. New indices, zeta q (generalized deviator strain evolution) and zeta(y)q (generalized deviator strain evolution rate), are proposed to evaluate the evolution and evolution rate of complex deformation. In the solid phase, the saturated coral sand primarily exhibits the properties of a continuous solid medium, the peak EPWP ratio (rup) shows a power correlation with generalized deviator strain evolution amplitude (zeta qa). While in the pseudo-fluid phase, the saturated coral sand primarily exhibits mechanical behavior characteristic similar to that of a fluid, and the rup shows a significant arctangent function relationship with generalized deviator strain evolution rate amplitude (zeta(y)qa). The correlation of rup with zeta qa and zeta' qaduring liquefaction is significantly affected by loading conditions (cyclic stress ratio, CSR, loading direction angle, alpha sigma, and loading frequency, f). To quantify the impact of these loading conditions on the generation of rup in different phases, unified indicators delta S (for the solid phase) and delta L (for the pseudo-fluid phase) are defined. Eventually, An EPWP model based on mechanical property exhibited in different phases is developed, which has normalized the effects of loading conditions. It provides a comprehensive framework to predict the rup of saturated coral sand under complex geological activities, and this model facilitates the understanding and simulation of the mechanical properties and behavior of saturated coral sand during the liquefaction process.

In order to analyze the adverse effect of flood affection on slope stability, the analytical expressions of buoyancy force and capillary force, hydrodynamic pressure and impact force, and scour erosion were proposed based on the aging characteristics of soil shear strength and limit equilibrium theory. According to the load combination and flood action, shear failure occurs preferentially at the foot of slope. Then, the plastic zone continues to extend upward to produce traction landslide disaster mode. Furthermore, the power function relation between shear strength index and time was established. The nonlinear accelerated creep model was also obtained. At the same time, the safety factor formula for flood loading effect slope aging stability, the time-varying characteristic value of anchor force and the compensation value of anchor force were also obtained and used to research sliding mechanism. In addition, the numerical calculation example shows that the slope safety factor decreases by more than 20 % considering the effect of flood ascending scour and impact, and the compensation value of anchorage force increases obviously with time increasing. Simultaneously, the change rate of compensation value of anchorage force increases nonlinearly with the increase of design safety factor.

The PHC (pre-stressed high-strength concrete) pile foundation, serving as an innovative supporting structure for solar power stations, is subjected to complex loading conditions in engineering scenarios. In this study, field tests of the full-scale PHC Pile foundation were conducted in sand layer, loess layer, and double-layer sites to investigate its operational behavior under different load conditions. The study assessed the inclination of the column top, ground displacement, and torsion to analyze the stress and deformation characteristics of PHC pile foundations. The deformation of PHC short pile foundations exhibited distinct phases. Torsional load reduced the column crack load by 30%. The pile cap effectively controlled plastic deformation, minimizing foundation deformation, while torsional load increased lateral deformation. Under cyclic load, the PHC pile behaved with an approximate elasticity characteristic within the test load range. The deformation increased by approximately 10%. Furthermore, three-dimensional numerical simulations analyzed the effects of foundation dimension, bending-moment-to-lateral-load ratio, torque-to-lateral-load ratio, and pile cap size on internal forces and deformation. Simulations indicated that increasing the pile cap length was more advantageous for reducing deformation and internal forces. The bending-moment-to-lateral-load ratio was significant in design, while the torque-to-lateral-load ratio had a negligible impact. A comprehensive design program is proposed based on field tests and numerical simulations, considering deformation and bearing capacity. The study confirms the reliability of the PHC pile foundation as a support structure for heliostats, aiming to offer valuable insights for practical applications.