Building Activities in Groundwater

Abstract

Groundwater is of great importance when building in unconsolidated rock and in bedrock, and knowledge of both the composition and discharge of the groundwater can be decisive in the implementation of a building project. Structures can lead to retention of the groundwater, but also can have a drawdown effect. In sticky unconsolidated rocks, the physical properties of the rock are often significantly altered by water in the rock pores and so groundwater has an effect on the bearing capacity, internal resistance and compressibility. In bedrock, the shear strength could be reduced by an increase of the pore water fraction in clayey rock layers on the joints. Hydrostatic pressure can lead to the upwelling of entire buildings or, even worse, individual parts of the building; this uplifting process can lead to significant structural damage. Furthermore, the chemical composition of the water and thus its effect on the building material, should also be taken into account because free carbonic acids, chlorides, sulfates and sulfides can corrode building materials. Therefore, in some cases, the composition of the building materials should be adapted to the groundwater quality; for example, the effect of sulfates can be inhibited by using sulfate-resistant cement in concrete. On the other hand, care should be taken that there are no negative impacts on groundwater quality due to the use of building materials.