Research Article| September 01, 1994 Hydraulic Forces That Play a Role in Generating Fissures at Depth DONALD C. HELM DONALD C. HELM Professor of Geology and Research Hydrogeologist Nevada Bureau of Mines and Geology, University of Nevada, Reno, NV 89557 Search for other works by this author on: GSW Google Scholar Environmental & Engineering Geoscience (1994) xxxi (3): 293–304. https://doi.org/10.2113/gseegeosci.xxxi.3.293 Article history first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation DONALD C. HELM; Hydraulic Forces That Play a Role in Generating Fissures at Depth. Environmental & Engineering Geoscience 1994;; xxxi (3): 293–304. doi: https://doi.org/10.2113/gseegeosci.xxxi.3.293 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyEnvironmental & Engineering Geoscience Search Advanced Search Abstract Throughout the southwestern United States, fissures are observed to develop in sedimentary material in response to ground-water withdrawal. Traditionally, two competing mechanisms have been posited to explain their occurrence. One is the viscous drag of flowing water on solid particles caused by horizontal seepage forces. The other is horizontal tension caused by flexure of a bending elastic plate in response to differential vertical movement along the base. In the present paper both of these suggestions are shown to be unsatisfactory for an assemblage of granular particles. The actual driving force on the aquifer (saturated assemblage of solid particles) is shown to be the difference between the driving force on the bulk material of solids and water together and the driving force on water relative to the solids. The latter is the seepage force. What is new is the bulk driving force.In response to pumping a single well at a constant rate, the driving force on the aquifer turns out to be proportional to the gradient of excess pore-water pressure, as used by geotechnical engineers. Another result of the present analysis is that when a pump is turned on, the aquifer is immediately set in motion towards the discharging well. This second result has far-reaching consequences. An external force is required to impede the inward radial motion of the aquifer. Such external forces can be supplied by the well screen itself, distant bedrock or heterogeneities—such as a subvertical heterogeneity that intersects the aquifer with cohesive or massive material on the far side. The fundamental question is consequently reversed. To find how fissures are generated at depth, we must search for forces that impede aquifer movement rather than for forces that drive it. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
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Donald C. Helm (1994) studied this question.