Read more. Holes and voids can be either concealed or open cavities that present naturally as a result of erosion and geological changes, or due to building, mining, and other commercial or industrial ground activity. Ranging from small to large, all holes and voids underneath structures will contain air, and possibly water, which can cause instability. Filling these spaces can prevent wider damage to the ground, on-ground structures, and the surrounding environment. Some holes and voids may need to be backfilled after operations cease, to prevent them becoming a hazard. Mainmark replaced the eroded sand fines behind the revetment wall with a lightweight void fill solution that would not erode or wash away. Holes are often dug in mining, building, and infrastructure works, while voids may develop over time due to leaks and weather eroding sub-soils underneath a structure.
What do holes and voids mean?
A void detection survey using Ground Penetrating Radar GPR is a low risk method to scan an area of ground and determine the location and extents of underground voids, sinkholes and subsidence. This can form part of a risk reduction process to check the integrity of the ground before moving or using heavy equipment and cranes, or to determine the extents of potential underground voids and subsidence to aid in remediation planning. Subsidence will be visible from the surface in the form of dipping ground in soft layers and cracks in harder materials. However, in cases when the surface is firm and supports its own weight the material beneath can subside until a significant void has developed underneath the surface layer with no visible warning signs.
Void detection using GPR
GeoModel, Inc. Professional Geologist will also observe geologic features in the area that may be related to any sinkhole activity or underground voids. To further investigate a sinkhole location or void location study, the GeoModel, Inc. Ground Penetrating Radar GPR produces a continuous record of subsurface soil and rock conditions, in the form of a cross-sectional profile. Radar profiles can be used for sinkhole location and void detection by observing the GPR data on the computer screen in real time. GPR image and model from a sinkhole location survey.
There have been several recent reports of collapsed roads at the various locations throughout the Bangkok metropolitan area. Most of the problems are caused by improper construction of utility networks and poor rehabilitation work. Ground penetrating radar GPR technique was selected to investigate the potential presence of subsurface voids under the road surface. In geotechnical and structural applications, GPR is an excellent tool for being able to image steel reinforcing bars, voids and tendon ducts in concrete structures and, more relevantly to this study, voids beneath concrete roads.