Volume 34, Issue 5 (September 2006)
An Alternative to a 3D Crack Monitor—4-Pin Algorithm
Cracks may appear in civil engineering structures, such as buildings, the body of a dam, its galleries, adjoining tunnels, and power plants during or after construction. Swelling or poor soils in the foundations, redistribution of stresses in the tunnels, creep of the materials, earthquakes or other vibrations are just a few reasons for cracks. The relative movements of the walls along and across the crack, and perpendicular to the plane of cracking surface or wall, beyond certain limits, may prove to be damaging. For considerations of safety and maintenance, the measurement of the magnitude and time rate of deformation of the cracks is essential. Instrumentation for deformation monitoring is of vital importance, especially in underground excavations in complex geological formations. A 3D crack monitor is used for 3D crack monitoring. The purpose of this paper is to show that by measuring points along and across a crack the same outcome can be determined with less effort and better precision.