Effect of root water uptake on road movement across seasonal changes

Abstract. The use of trees as roadside barriers provides benefits like noise and pollution control. On the other hand, the root systems can disrupt soil moisture, leading to uneven subsidence and impacting nearby structures. Knowing the appropriate distance between trees and pavement will allow for maximizing the plant's favourable impact on infrastructure. This study aimed to determine the safe distance between trees and pavement by examining the effects of transpiration on pore water pressure (PWP) and pavement subsidence under seasonal variations. The root water uptake was simplified in a finite element model using multiple hydraulic head boundaries and validated through field observations. A hypoplastic model was employed to simulate the non-linear behaviour and plastic strain accumulation in unsaturated soil. The findings indicate that the summer season exhibited a more noticeable change in negative PWP. Trees significantly reduce PWP, especially during summer seasons, creating higher suction near them due to evapotranspiration. Additionally, pavement edges closest to trees experience the most pronounced subsidence, likely due to a greater soil moisture deficit. Seasonal variations influence subsidence, with drier periods leading to more severe effects. Furthermore, the pavement with the distance 4 meters from the tree highlights a potential risk exceeded the cracking moment at 5th summer period, indicating a high risk of damage.