Penetration Lengths of Agar Gum and Gellan Gum Used for Injection Grouting into Porous Media at Different Pressures

In the context of ground improvement applications, this study analyzes the radial penetration length during the permeation grouting of thermal gelation biopolymers (TG-BP) into granular soil. Two types of TG-BP were employed, agar gum (AG) and gellan gum (GG). The penetration length was analyzed using a Hele-Shaw cell apparatus to evaluate the effect of pressure injection on the radial penetration length. It was found that viscosity played a key role in permeation of the biopolymer grouts. Thus, a temperature range of 70–90°C was used to maintain the low viscosities of the AG and GG solutions at concentrations of 0.25 wt%, 0.5 wt%, 1 wt%, and 1.5 wt%. A two-dimensional (2D) test was conducted, and the accuracy of its results was evaluated through a one-dimensional (1D) test. The results showed that in the 2D test, the penetration length increased as the injection pressure increased for both biopolymers (AG and GG), thereby correlating with the results of the 1D test. Moreover, an injection test indicated a significant increase in the permeation length with a decreasing effective viscosity at higher injection pressures. At the same effective viscosity and pressure, the penetration length was identical, even for different grout materials.