Soil Quality Improvement of Silty Soils Using Cement for Soil-Cement Weir Construction in Mueang Chiang Rai District

Abstract

This study aims to evaluate the potential of improving the engineering properties of silty soils in Mueang Chiang Rai District using cement stabilization for application in soil-cement weir construction. Soil samples were collected from sediment-accumulated areas and subjected to laboratory testing to determine physical and engineering properties, including optimum moisture content, unconfined compressive strength, permeability, and shear strength. The results indicated that incorporating 25% cement by dry weight significantly enhanced the soil's strength and reduced its permeability. In addition, the maximum dry density of the stabilized soils reflected a denser soil structure, which enhances the load-bearing capacity of soil-cement applications in flood protection systems. A soil-cement weir with a height of 2 meters, 1:1 side slopes, and a central cut-off trench was designed and analyzed using both the Limit Equilibrium Method (LEM) and Finite Element Method (FEM). The analysis revealed that the soil-cement structure satisfied or exceeded the minimum safety factor requirements under all critical conditions, while also exhibiting acceptable settlement and seepage performance. These findings demonstrate that locally sourced silty soils, when treated with cement, can be transformed into a structurally sound, cost-effective, and sustainable construction material for flood control applications in high-risk areas. The proposed weir design contributes to enhanced resilience in flood-prone communities and supports the sustainable use of local resources in geotechnical and hydraulic engineering practices.