Flume test demonstration of landslide in stable gentle soil slope triggered by small mass of pressurized pore gas

Abstract

<p>This paper presents a triggering factor causing landslide in stable gentle soil slope. The triggering factor is a small mass of pressurized pore gas in the soil slope and illustrated with a flume soil slope model. The pore gas has a small mass of oxygen and is generated via the injection of a small volume of H2O2 solution into the cement powder core of the soil slope. The core is covered by a layer of saturated soft clay that forms a trap for the new pore gas to build its pore gas pressure. The pore gas pressure is the driving force to cause the landslide in the stable gentle soil slope. The mass of the pore gas is smaller than 0.1% of the mass of either the gentle soil slope or the landslide body. The videos of the landslide are captured and used for the analysis of movement and displacement of the sliding soil mass with time. The pressure of the pore gas is estimated from the acceleration model of the sliding soil mass. A calibration test is further carried out for the generation of the oxygen gas mass and pressure via the decomposition of the H2O2 solution in cement powder. The results quantitatively demonstrate that the small mass of the oxygen gas in the voids of the cement powder core can have enough pressure to trigger the landslide in the stable gentle soil slope model. Such pressurized pore gas triggering factor is generally not noticeable since its mass can be very small and disappear rapidly without a trace. This triggering factor could be responsible for the huge and disastrous landslide that suddenly and dramatically occurred in a huge gentle fill soil slope on December 20, 2015, at Hengtaiyu Industrial Park, Shenzhen, China.</p>