Construction on Slow-Moving Landslides: Effects of Excavation on Neighboring Structures

Abstract

In mountainous areas, urban development often takes place on slow-moving ground, which over time may inflict severe damage on buildings and infrastructure. This process can be accelerated significantly by new construction near existing structures. Although for stable ground conditions the problem of excavation-induced damage has been studied extensively, for slow-moving landslides the question of how to reduce damage to neighbors remains open. This paper presents a general finite-element modeling procedure which allows for a full-scale investigation of the landslide excavation problem. The evaluation of structural damage follows an existing approach, in which the effect on the neighboring buildings is deduced from greenfield displacements, using the limiting tensile strain method, correlated with damage categories. The results of the study, which was inspired by real landslide cases, show that failing to estimate the correct compression state of the landslide can lead to significantly higher damage to close neighbors than in the case of a stable slope. Designing the anchors close to the true in situ earth pressure reduces the damage potential, but can result in enormous anchorage costs, if situated in a compressed landslide zone. Excavating farther from neighbors allows for a significant reduction in the required anchor support, which the proposed procedure helps to quantify. Another distinctive feature of excavations within landslides is the development of considerable compressive strains in the sliding direction along the lateral sides of the excavation. It is shown that these compressive strains also have the potential to damage neighboring buildings.