Status Of Rock Mechanics As Applied To Civil Engineering

The objective of this papef is to summarize briefly the practical use of rock mechanics in design and construction of various types of structures. These range from foundation for industrial facilities, nuclear power plants, bridges and dams to tunnels and underground caverns. The use of rock mechanics has varied from performing a few laboratory unconfined compressive tests on core samples to complete field and laboratory tests for underground power caverns. The primary difference between the rock mechanics studies we hare for construction projects and those most commonly found in the literature is that our tests must provide immediate answers to specific questions facing a design or construction engineer. For example, when we make a plate-bearing test we arrive at a load-deformation relationship. We realize that this is not a true modulus of elasticity. Yet, when considering the resistance the rock will provide against forces occurring in a pressure tunnel it is a far more useful value than the true modulus of elasticity of the rock. Another example of this difference in interest is in the use of flat jacks. Many people criticize the use of flat jacks because they measure the stresses in the disturbed zone very near the surface and do not represent the undisturbed stress condition in the rock. However, in actual construction it is frequently those near-surface stresses with which we must cope. We are interested in both the stress conditions present prior to excavation and those as modified by construction of an exploratory adit or drift. Fundamentally, we are interested in the practical application of rock mechanics in the solution of problems of design and construction of civil engineering works.