This study conducted an experimental and numerical investigation on the stabilization of clayey subgrades using nano-silica and geogrid reinforcement. Nano-silica was incorporated in varying contents (0-4%) to assess its effects on Atterberg limits, compaction behavior, shear strength, and California bearing ratio. The results showed optimal performance at 2.5% nano-silica, with reduced plasticity index and enhanced dry density, cohesion, friction angle, and bearing capacity. A three-dimensional finite element model was developed to simulate subgrade behavior under cyclic loading, incorporating the effects of both nano-silica and geogrid layers. The model was calibrated using laboratory data to reflect observed settlement and stress distribution. The numerical results confirmed that nano-silica reduced settlement significantly up to the optimal content, while geogrid reinforcement further enhanced load distribution and reduced displacement. The combination of nano-silica and geogrid resulted in improved mechanical performance of the subgrade. These findings demonstrate the effectiveness of integrating chemical stabilization and mechanical reinforcement in clayey soils to improve structural capacity and reduce long-term deformation, providing a viable solution for pavement subgrade enhancement.

The challenges related to sanitation and water management in new urban communities have contributed to the emergence of visions of Integrated Urban Water Management (IUWM) and Water Sensitive Urban Design in cities worldwide to keep pace with these subtle changes the shape of the urban environment. This research paper aims to monitor the main obstacles and challenges facing residents of new cities in Egypt and the environmental impacts resulting from those challenges in the urban context. A questionnaire was conducted among a group of the population. This study took the economic houring model for low-income people in the 6th of October City in Egypt as a case stud. As a result, the study found that the main challenges facing the residents of these areas and their impacts are: I 1) Lack of regulag maintenance. 2) Health risks to the population. 3) Damaging of public parks and gardent. 4) Pollution of the surounding environment, including soil and water. 5) Lack of state funding for maintenance and Limited financial resources available for projects in this type of housing. 6) Lack of government engagement in preparing programs to raise population awareness and clarity in environmental goals and quality of life policies. 7) Lack of community initiatives to participate in decision-making. 8) Lack of political guidance on planning processes for sustainable infrastructure.