The grid hard crust (GHC), an innovative artificial structure formed by in situ solidification, comprises an upper hard crust layer and lower cement soil walls. Compared with the conventional single-thickness hard crust (STHC), the GHC achieves a lower total cement mass \(m_c\) while maintaining comparable settlement control. However, its application has been limited by the lack of a comprehensive design theory. This study develops an analytical model for predicting GHC deformation by integrating Timoshenko foundation beam theory, the structural displacement method, and nonlimit-state earth pressure theory. The model computes four deformation parameters: the maximum vertical displacement \(y_{\text {max}}\) , the differential settlement \(\Delta _{\text {max}}\) , the horizontal displacement \(x_{\text {max}}\) , and the stress efficiency \(\eta _{\text {load}}\) . The proposed model is validated against PLAXIS 2D simulations and field tests, showing good agreement. A parametric study further identifies key influencing factors and establishes preliminary design ranges for critical parameters. Furthermore, Non-dominated Sorting Genetic Algorithm II and Technique for Order Preference by similarity to ideal solution are applied within a multiobjective optimization framework to form a complete design methodology. In a case study, the optimized GHC design demonstrates a 10.2% reduction in \(m_c\) with the STHC, highlighting its significant potential for sustainable soft soil improvement.
