APPLICATIONS OF GEOPHYSICS IN 

 ENGINEERING 



Applications of geophysical methods in engineering are of fairly recent 

 date. Although many engineering problems may be attacked by geo- 

 physics, developments have been slow for various reasons: (1) information 

 on the possibilities of geophysics has not been readily available to engineers ; 

 (2) few engineering projects compare in commercial scope with oil and 

 mining projects; (3) in near-surface engineering problems geophysical 

 exploration has to complete with surface geology and drilling. It is unfor- 

 tunately true that numerous engineering projects are still undertaken 

 without consulting a geologist. With an increased appreciation of the 

 advantage of geological advice, an increase in the number of applications 

 of geophysics to engineering problems will undoubtedly follow. 



Engineering applications of geophysics may be divided into two classes : 

 (1) geological, and (2) nongeological. 



I. GEOLOGICAL APPLICATIONS 



These are concerned with: (a) foundation problems; (b) location of 

 construction materials, and (c) water location, 



A. Foundation Problems 



As shown in Table 4, special problems in this category are: determina- 

 tion of depth to bedrock, of type of rock encountered in dam, aqueduct, 

 canal, tunnel, shaft, harbor, bridge, railway, highway, tramway, subway, 

 and other construction projects. Similar problems in the field of military 

 engineering are tests of foundations for military roads, railroads, shelters, 

 forts, and other underground mining operations. They are best attacked 

 by seismic-refraction and electrical-resistivity and potential-drop-ratio 

 methods. The seismic-refraction method is aided by the considerable 

 velocity contrast existing between overburden and bedrock. Similar con- 

 ditions prevail in electric potential surveys, since the resistivity of the 



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