Influence of different subsidence-related drivers on damage to existing buildings

Abstract

Subsidence is a significant geohazard affecting many areas globally, including the western part of the Netherlands. Subsidence is the lowering of the ground relative to the surface level, and it occurs both on the scale of a single structure and larger areas. The shallow subsurface in these areas, characterized by compressible soil, contributes to subsidence, which may be initiated or intensified by additional drivers. Subsidence can cause damage to buildings, leading to increased costs and social concerns

In the current state of the art, less distinction is made regarding the difference in effects between different subsidence drivers. This study aims to provide insights into the relative influence of different drivers on the damage to existing buildings with a shallow foundation. More specifically, it aims to understand how various conditions and factors influence the damage parameters associated with soil deformation. This approach allows for analysing the interactions between the soil and the structure, ultimately contributing to a better understanding of the relative influence of the different drivers.

Numerical models in PLAXIS 2D have been carried out to compute settlements for various scenarios, involving different soil scenarios, building scenarios, and subsidence drivers. The primary emphasis of numerical modelling lies on the soil rather than on the structure itself. Various damage parameters have been established based on the numerically calculated settlements. The purpose of this analysis is to determine the impact of settlements on the building based on these damage parameters.

Several aspects related to settlement occurrence and its impact on buildings were investigated. The study provides multiple outcomes regarding the interaction between soil scenarios, different drivers of subsidence, and the presence of an existing building with and without a partial basement. This was achieved by considering the influence of each of these variables on the damage parameters, with emphasis placed on the relative influence of the different drivers. The approach includes a method that compares the influence of the situation with the existing building and the situation without the existing building (greenfield situation). This comparison shows the settlement behaviour caused by the presence of the building load and its interaction with the soil. Additionally, the combined effects of the soil scenarios, different drivers, and building scenarios on the resulting damage to an existing building are considered.

To conclude, for the soil scenarios considered in this study, the soil scenario with a weak spot (SS3) has the most unfavourable effect on an existing building. For the drivers considered in this study, when evaluating the relative influence of the different drivers, the global groundwater lowering (D2glo) has the most unfavourable effect. Considering the combined effect, the soil scenario exerts the greatest influence on the resulting damage parameters for the evaluated scenarios, followed by the type of driver and the building scenario.