Liquefaction within a bedding fault: Understanding the initiation and movement of the Daguangbao landslide triggered by the 2008 Wenchuan Earthquake (Ms = 8.0)

A state-of-the-art review of polymers used in soil stabilization

Abstract An accurate analysis of fracture and cleavage anisotropies along two landslides in the Argentera massif (French Southern Alps) was performed in order to relate the fracturing mode to the rock slope failure state. The mature La Clapiere landslide and the incipient Isola Landslide were investigated. In both cases, the gneissic rock schistosity was found sub-horizontal in the vicinity of the landslides at shallow depths, while it was sub-vertical elsewhere at the massif's scale. In addition to the well known regional tectonic fracture sets, we identified in both cases a new family of vertical valley parallel (VP) fractures. The VP fractures were only observed on the lower part of slopes affected by landslides where schistosity was found sub-horizontal. The VP fractures are clearly related to the decrease in schistosity dip and correspond to ‘fold extrado’-like joints. The proximity of the schistosity folds and the associated VP joints to the landslides suggests that they are gravity-driven. The presented 2-D finite-difference models of the slope destabilisation in the La Clapiere site shade light on possible mechanisms of the indicated gravity-induced processes. A progressive degradation of the material strength was imposed in these models to simulate the weathering effect which led to inelastic deformation/damage at the lower part of slope. This was followed by the formation of dense sub-vertical deformation bands and then by the initiation of a landslide in the area corresponding to the actual position of the La Clapiere landslide. It is suggested that the gravity-induced damage in the lower part of slope increases the permeability and thereby accelerates the weathering that causes a more rapid strength reduction. The latter results in the tilting/folding of pre-existing fabrics and the related VP fracturing. The La Clapiere landslide is initiated in the upper part of this zone.

Evolution of gravity-driven rock slope failure and associated fracturing: geological analysis and numerical modeling

Polymers have been widely known as nontraditional soil stabilizers capable of replacing common soil additives to reach superior soil stabilization outcomes. While numerous studies represent...

Effects of Curing Method and Glass Transition Temperature on the Unconfined Compressive Strength of Acrylic Liquid Polymer–Stabilized Kaolinite

Characterizing the spatial distribution, frequency, geomorphological and geological controls on landslides triggered by the 1933 Mw 7.3 Diexi Earthquake, Sichuan, China

Silty sand can be prone to erosion because it is short of stability cementation materials. In recent years, various emerging soil stabilizers, especially natural organic substance and polymer, have been used to improve soil strength, water stability and ability of erosion resistance. In this study, a new type of soil stabilization additive modified carboxymethyl cellulose (M-CMC), consisting of carboxymethyl cellulose (CMC) and polyacrylamide (PAM), was developed for stabilization treatment of silty sand. A series of laboratory tests were conducted to evaluate the performance of M-CMC application on shear strength, permeability, water susceptibility and microstructure of the silty sand soil treated with additive concentration range of 0% - 1.3%. Moreover, rainfall simulation experiments were conducted to evaluate the effect of M-CMC on the erosion control of silty sand which compacted soil in a large-sized runoff (1 m2) plots. Test plot which treated with 1.1% concentration of soil stabilizer and control plot which treated with same amount of water were cured outdoor for 50 days before rainfall simulation test. Rainfall intensity was applied at 120 mm·h-1 for 60 min. Finally, a field test is performed in order to assess the practical application effect of silty sand with 1.1% M-CMC. In general, the results showed that an increase of the concentration of M-CMC resulted in an improvement in water susceptibility and shear strength but a decrease in the infiltration rate. Internal friction angle of the treated soil remarkably increased under a low M-CMC concentration (less than 0.7%), while cohesion of them sharply increased under a relatively high M-CMC concentration (larger than 0.7%). Water susceptibility of the treated samples was improved remarkably under a relatively high M-CMC concentration (larger than 0.7%). Permeability coefficient of them decreased significantly when the M-CMC concentration was increased from 0 to 0.5% and, then, from 0.9% to 1.3%. Based on the images obtained from a scanning electron microscopy (SEM), the “coating” and “netting” effects were attributable to the observed improvement of the treated soil. When a plot was protected by a thin layer of soil treated with 1.1% MCMC, its erosion resistance was greatly improved, infiltration rate of water and soil loss yield of plot decreased greatly and even though under a rainfall intensity of 120 mm·h-1. The field test with long-term monitoring (three years) confirmed the M-CMC can effectively control erosion of silty sand slopes for a prolonged period of time.

Qingwen Yang

Papers

Liquefaction within a bedding fault: Understanding the initiation and movement of the Daguangbao landslide triggered by the 2008 Wenchuan Earthquake (Ms = 8.0)

Impact of polymer mixtures on the stabilization and erosion control of silty sand slope

Geological and morphological study of the Daguangbao landslide triggered by the Ms. 8.0 Wenchuan earthquake, China