Effects of water content on shear properties of bentonite–polymer composite structure

Abstract

Abstract Understanding mechanical behavior at the soil–structure interface is fundamental for safety in engineering and is therefore an important consideration in structural design. Buildings can be deformed or severely damaged by shear forces from the action of earthquakes, waves, or winds. It is therefore necessary to understand the conditions which lead to structural failure at the soil–structure interface under shear action. We investigated the strain and displacement of bentonite–polymer specimens at various moisture contents. Shear failure was investigated using novel shear test equipment consisting of a two-dimensional soil fracture test device and computerized digital image correlation (DIC) technology. Analysis of the shear test results revealed the mechanical properties of bentonite–polymer composite structure under shear stress. Experiments showed that there were four stages in the failure of the bentonite–polymer samples: an increasing stress stage, a pre-damage stage, an abrupt damage stage, and a stable stage. At the instant the shear stress reaches peak value, the strain in the bentonite was greater than that in the polymer at the same position. In the failure stage, the bentonite at the middle and upper levels of the bentonite–polymer interface cracked first. Increased moisture content in the bentonite weakens the shear performance at the bentonite–polymer interface, and brittle failure was most significant when the moisture content was optimal.