MATHEMATICAL MODELS OF GROUND-WATER FLOW AS AN AID FOR PREDICITING SLOPE STABILITY IN TAILINGS-POND EMBANKMENTS

RECENT DEVELOPMENTS IN THE CONTROL OF MINE TAILINGS AND ASSOCIATED WASTEWATER HAVE PRECIPITATED A NEED FOR THE CONSTRUCTION OF INCREASING NUMBERS OF TAILINGS PONDS. THE EMBANKMENTS OF SUCH PONDS RETAIN WASTEWATER WHILE SUSPENDED SOLIDS SETTLE OUT. SUBSEQUENTLY, WATER IS DECANTED FROM THE SURFACE OF THE POND. DESIGN OF STABLE OF EMBANKMENT SLOPES, AND AN UNDERSTANDING OF THE FLOW RATE OF SUBSURFACE WATER FROM INSIDE THE POND THROUGH THE EMBANKMENT AND UNDERLYING MATERIAL TOWARD THE REGIONAL WATER TABLE OUTSIDE THE POND, ARE OF PARAMOUNT IMPORTANCE TO PUBLIC SAFETY. THE CONFIGURATION OF THE PHREATIC SURFACE WITHIN THE EMBANKMENT IS A PREREQUISITE TO SAFE SLOPE DESIGN. SIMILARYLY, THE GEOMETRY OF THE PHREATIC SURFACE INFLUENCES THE SUBSURFACE TRANSPORT OF WATER AND ITS DISSOLVED CONSTITUENTS OUT OF THE POND. MATHEMATICAL MODELS THAT SOLVE THE LAPLACE OR RICHARDS EQUATION NUMERICALLY CAN BE UTILIZED IN TWO WAYS: TO LOCATE THE PHREATIC SURFACE WITHIN THE EMBANKMENT, AND TO DEFINE THE SUBSURFACE FLOW SYSTEM THAT TRANSPORTS WATER OUTWARD FROM THE POND. INPUT DATA NEEDED FOR THE MODEL INCLUDE (1) THE SATURATED HYDRAULIC-CONDUCTIVITY (PERMEABILITY) DISTRIBUTION WITHIN AND BENEATH THE EMBANKMENT, (2) THE FLUID POTENTIAL VALUES UP-GRADIENT AND DOWN-GRADIENT FROM THE EMBANKMENT, AND (3) THE GEOMETRY AND ELEVATION OF AN APPROXIMATELY IMPERMEABLE LAYER AT SOME DEPTH BENEATH THE EMBANKMENT. THE PRESENT STUDY INDICATES THAT PERMEABILITY DISTRIBUTIONS IN EXISTING EMBANKMENTS MAY BE FAIRLY CONSISTENT. IF THIS OBSERVATION PROVES TO BE VALID, IT MAY BE POSSIBLE, PRIOR TO CONSTRUCTION, TO USE MATHEMATICAL MODELS AS PREDICTIVE DEVICES FOR SAFE-SLOPE DESIGNS AND FOR ANALYSIS OF THE FLOW OF WATER FROM TAILINGS POND VIA THE SUBSURFACE. /AUTHOR/

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Filing Info

  • Accession Number: 00237918
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 26 1971 12:00AM