Safety Concerns in Geotechnical Engineering
Sudhir Kumar Tewatia
Researcher, Central Soil & Materials Research Station, Ministry of Water Resources, Outer Ring Road, Hauz Khas, New Delhi, India
Director, Central Soil & Materials Research Station, Ministry of Water Resources, Outer Ring Road, Hauz Khas, New Delhi, India
Swelling soils in the foundations may pose the problem of inducing damaging cracks in civil engineering structures. Underground excavations are often required in geotechnical engineering not only for hydro-power projects but for roads and railways etc. also. Besides the head-race, tail-race and access tunnels and power house caverns, cavities are also required for transformers, galleries, de-silting chambers and other accessories. Cracks may appear in civil engineering structures, such as buildings, cavities, the body of dam, its galleries, adjoining tunnels and power plants etc. during or after the construction. Swelling soils in the foundations, redistribution of stresses in the cavities/tunnels etc., creep of the materials, earthquake or some other vibrations etc. may be just a few of the many other reasons for the cracks. The relative movements of the walls along and across the crack, and perpendicular to the plain of cracking surface or wall, beyond certain limits, may prove to be potentially damaging. For the considerations of safety and maintenance, the measurement of the magnitude and time rate of deformation of the cracks is essential. Instruments play a vital role during construction of underground structures. Instrumentation for deformation monitoring is of vital importance especially in underground excavations in complex geological formations. However, the purpose of an engineer is to increase the safety and to reduce the cost. 3D crack-monitor is generally used for 3D crack-monitoring. A simple method is suggested here that does not require 3D crack monitor. The method provides an in-built check on the accuracy of method, results and observations.
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