Shear Parameters of Rammed Earth Material: Results from Different Approaches

Abstract

Rammed earth (RE) is a construction material which is manufactured by compacting the soil in a formwork, in different layers. Several recent studies have investigated this material. The seismic performance of RE buildings is an important topic which needs to be carefully investigated. The complex numerical model seems a performant approach to investigate the seismic performance of a whole building. To correctly establish the model, the shear parameters of the material, which are the cohesion and the friction angle, should be identified. This paper first presents experimental studies on the shear parameters of RE through the direct shear tests, at two different scales. The differences of the results at different scales are analyzed. Then, the obtained experimental values are used in a numerical model to simulate the shear behavior of RE walls which are loaded by a constant vertical stress and pushed horizontally on the top. From the obtained results, the values for numerical models are recommended.

Assessing the Seismic Behavior of Rammed Earth Walls with an L-Form Cross-Section

“…The differences between the intralayers and interlayers are due to the mode of fabrication: the upper parts of a RE layer are better compacted than the lower parts. The differences were observed in previous studies (for example reference [21]) and the detailed behavior are detailed in the following sections.…”

“…The numerical investigations were conducted with the finite element method (FEM) by the Abaqus software [20], which has been widely used for the structures with conventional materials such as steel, concrete and masonry. Several studies in the literature have used FEM to simulate the mechanical behavior of RE walls (for example references [8,13,15,17,21]), however, to our knowledge, no study using FEM and applying the time history analysis has been presented. Besides the FEM used in this study, the discrete element method (DEM) which had largely been developed to model masonry walls [22] was also a relevant approach to model RE walls [9,19,23].…”

“…In the present study, the RE wall was modeled as the assemblage of compacted earth layers (called "intralayers") which were connected by the "interlayers" which had lower mechanical characteristics [21]. The interlayers were supposed to have 5mm of thickness instead of introducing an interface law.…”

Experimental and Numerical Research on Utilizing Modified Silty Clay and Extruded Polystyrene (XPS) Board as the Subgrade Thermal Insulation Layer in a Seasonally Frozen Region, Northeast China

“…where λ MC (θ) is the thermal conductivity of MC considering its moisture content but not F-T cycles; θ is the moisture content of MC. The coefficient of determination denoted R 2 = 0.98 indicates that Equation (8) fits well on the thermal conductivity and moisture content of MC, because in some literatures [36,37], R 2 ≥ 0.90 is a judgment basis which fit curve is very suitable to represent the variation trend of fitting data points. Results in Figure 4B show the calculation model of MC thermal conductivity considering F-T cycles as Equation 9:…”

Dynamic Response Law of Loess Slope with Different Shapes

“…Sassa [5] proposed a landslide motion model considering the influence of pore pressure; Wang and Zhang [6] proposed the mechanism of earthquake-induced high-speed loess landslide-loess disintegration, oblique projectile motion, and dust-forming effect of loess mass; Keefer [7] classified seismic landslides into three categories according to motion characteristics and destructive effect thereof; Prestininzi and Romeo [8] presented the relation between seismic intensity and earthquake-induced landslide; Scheidegger [9] proposed the slide friction model of landslide mass; Jibson and Keefer [10] and Romeo [11] discussed how to determine the acceleration-time history of ground motion using Newmark analysis method; and other scholars studied on the influence of ground motion parameters upon dynamic response of a slope [12][13][14][15][16][17][18]. Nevertheless, research on seismic dynamic response of loess slope has up to now seldom focused on the factors related to the slope shape such as slope type and slope ratio, undoubtedly leaving hidden troubles for the safety of engineering construction in the loess regions prone to high-intensity earthquake [19][20][21][22]. In this paper, the typical stepped loess slope in engineering construction is taken into consideration as the research object, and the numerical analysis model is established by using FLAC3D software to study the dynamic response of loess slopes with different shapes.…”