Feasibility Study on Liquefaction Mitigation of Fraser River Sediments by Microbial Induced Desaturation and Precipitation (MIDP)

A bio-mediated ground improvement technique known as microbial-induced desaturation and precipitation (MIDP) via denitrification can be used to introduce biogas and bio-minerals into the soil matrix. A feasibility study was performed to assess the potential of MIDP to stabilize sediments under an embankment along the Fraser River in Richmond, a coastal city in Canada. Locally collected sediments were subjected to multiple MIDP treatment cycles under similar stress conditions as expected in the field using a modified triaxial test set up. The hydraulic conductivity was determined after each treatment cycle. The mechanical response of the treated soil was evaluated under undrained loading conditions. Results show that with increasing treatment cycles, the hydraulic conductivity decreased significantly. The original tangent modulus increased with the number of treatment cycles as did the slope of the straight line passing through the phase transformation point in the effective stress path plane. The effective stress paths of treated samples almost merged, and they lie somewhere between the drained and undrained lines.