Modeling rammed earth wall using discrete element method

Abstract

Rammed earth is attracting renewed interest throughout the world thanks to its "green" characteristics in the context of sustainable development. Several research studies have thus recently been carried out to investigate this material. Some of them attempted to simulate the rammed earth's mechanical behavior by using analytical or numerical models. Most of these studies assumed that there was a perfect cohesion at the interface between earthen layers. This hypothesis proved to be acceptable for the case of vertical loading, but it could be questionable for horizontal loading. To address this problem, discrete element modeling seems to be relevant to simulate a rammed earth wall. To our knowledge, no research has been conducted thus far using discrete element modeling to study a rammed earth wall. This paper presents an assessment of the discrete element modeling's robustness for rammed earth walls. Firstly, a brief description of the discrete element modeling is presented. Then, thirteen parameters that were necessary for discrete element modeling were identified. The relevance of the model and the material parameters were assessed by comparing them with experimental results from the literature. The results showed that, in the case of vertical loading, interfaces did not have an important effect. In the case of diagonal loading, model with interfaces produced better results. Interface's characteristics can vary from 85% to 100% of the corresponding earthen layer's characteristics.

Shear Parameters of Rammed Earth Material: Results from Different Approaches

“…e wall was modeled with 12 layers of 11.4 cm each (named "intralayer") and thin layers of 1 cm (named "interlayer") between the earthen layers. Indeed, the role of the interlayers may not be predominant in the case of vertical loads but important in the cases where the interfaces are more solicited [17]. In the present study where the walls are subjected to horizontal loads, the e ects of interlayers on the model might have a signi cant impact on the results.…”

“…For the numerical modelling, due to the simplicity, the earthen layers are usually assumed homogeneous and the interfaces are added between layers [17]. However, the above experimental results showed that there was a difference in the cohesions and the friction angles between the upper and middle parts of an earthen layer.…”

“…In order to study the earthquake behavior of an entire RE structure, robust numerical models are a necessary approach. For the numerical modelling of RE material, two important shear parameters are the friction angle φ and the cohesion c. Due to the superposition of successive earthen layers during the manufacture of RE walls, two kinds of characteristics should be distinguished: characteristics of the earthen layers ("intralayer") and those of the interfaces between earthen layers ("interlayer") [17]. e first scope of the present study is to identify the relevant values of the friction angle φ and the cohesion c for both intralayers and interlayers.…”

“…Nowamooz and Chazallon [20] used finite elements modelling with the Barcelona model on small compacted soil specimens and identi ed a friction angle and a cohesion of 41°and 13.4 kPa, respectively. Bui et al [17] used discrete elements modelling to identify c and φ; the identi ed friction angle was of 45-50°a nd the identi ed cohesion was of 100-150 kPa. Miccoli et al [21,22] identi ed numerical values of 30-45°for intralayer friction angles.…”

In-Plane Behaviour of Earthen Materials: A Numerical Comparison Between Adobe Masonry, Rammed Earth and Cob

“…In last decade several studies were carried out to numerically model the behaviour of earthen materials under static [7,8,9,11,12,13,14,15,16,17] and under pseudo-dynamic loading [18,19,20]. This article presents a comparative study on the numerical modelling of three different earthen materials under static in-plane loading.…”