Architects make the most noticeable changes to our landscape. They determine what the skyline will look like, where we will live, and how we think about our living environment. The land is also determined by the civil engineers who plan and build our roadways and bridges. These structures are built to last. Considering the size of the investment in millions, even billions, of dollars, a sturdy, solid structure is the first requirement. However, the earth that these structures are built on is anything but sturdy and solid. For this reason, the architect and civil engineer need to start the design process with a relationship with a geotechnical consultant. Geotechnical consultants have a full understanding of the properties of the earth and how structures must take these properties into account.
When we think of properties of the earth that can destabilize a structure, we probably think first of earthquakes. In places such as California that are spider-webbed with geological faults, earthquake-proofing is the first consideration. These geological faults are the result of the slow, gradual movement of the earth’s tectonic plates. As these plates move, they slowly grind their way against the neighboring plates. When buildings are to be built in construction monitoring these areas, the geotechnical engineer studies the fault structure and history of the area to determine how the foundation of the new building, roadway, or bridge must be configured so that it will not collapse if an earthquake strikes. It must be remembered that California isn’t the only area that has experienced earthquakes. They also occur in such unexpected areas as Missouri, Ohio, and North Carolina.
Earthquakes aren’t the only phenomenon that can undermine the foundation of a structure. Two others are landslides and rock falls, which are very similar. In the case of these phenomena, problems can occur at both ends. If the building it at the top of the hill, it can slide down. If it is at the bottom of the hill, it can be buried in falling debris, and people below can be injured by falling rocks. Areas of falling rock can occur where the hill structure consists of rock such as limestone that contains many cracks. If water seeps into the cracks as winter approaches, the water can freeze. As we all know, when water freezes, it expands. This expanding ice acts like a wedge, putting stress on the cracks and causing it to crumble. This crumbling rock then falls down the hill.
Another source of instability in the earth is underground water. The first place we think of with this potential problem is the watery State of Florida. Geotechnical engineers have to ensure that structures will not be undermined by sinkholes or soil liquefaction. Sophisticated testing is needed because it may not be easily determined that an area is prone to sinkholes unless they have been seen historically.
But land isn’t the only place where this type of study is needed. Watery areas also need to be evaluated when a pier is or wharf is to be built.
As you can see, consulting a geotechnical engineer is a vital first step in developing a new structure, whether it is a skyscraper, road, bridge, or wharf is to be built.