Experimental Study on the Effects of Water Retaining Agents in Ecological Substrates on Soil Properties

Abstract With the deepening of sustainable development concepts, vegetation protection has become the primary method for highway slope protection and has seen widespread application. Among these, the type and properties of substrate materials significantly affect the protective effectiveness, making it a core issue in vegetation protection. In arid regions, where rainfall is scarce and evaporation rates are high, water retention becomes a key focus in the study of ecological substrates. This study, focusing on the semi-arid regions of the Northern Hemisphere, investigates the effects of varying water-retaining agent content on soil water retention and mechanical behavior through laboratory evaporation tests and triaxial compression tests. By examining crack development during the evaporation process, the study reveals the micro-mechanisms by which water-retaining agents influence soil properties. The findings are as follows: (1) Water-retaining agents can effectively reduce the evaporation rate, with higher contents leading to slower evaporation and stronger soil water retention capacity; (2) The agents have little effect on the overall strength of the soil but primarily alter the soil’s deformation behavior, reducing cohesion while having minimal impact on the internal friction angle; (3) The hydrological properties of soils containing water-retaining agents are unstable and prone to cracking under dry conditions. Therefore, the content of water-retaining agents should be carefully calibrated according to the geotechnical properties of the protective slope, and in the early stages of ecological protection, surface evaporation prevention measures should be implemented to avoid surface cracking.