UNSTABLE EMBANKMENT, US 119

THE SLIDE IS ABOUT 500 FEET IN LENGTH AND 170 FEET IN WIDTH. THE FAILURE SURFACE IS LOCATED NEAR OR SLIGHTLY BELOW THE EMBANKMENT AND COLLUIUM-SHALE ROCK INTERFACE AND THE UNSTABLE SOIL MASS CONSISTS OF APPROXIMATELY 50,000 CUBIC YARDS OF MATERIAL. THE MOVEMENT IS IN A DIRECTION ALONG A LINE PARALLELING THE NOSE OF A FAULTED ANTICLINE. THE MASS HAS APPARENTLY BROKEN INTO TWO PARTS AND THE LEFT AND RIGHT UPPER PORTIONS ARE MOVING ABOUT SIX TO SEVEN TIMES FASTER THAN THE BOTTOM CENTER PORTION. THAT THE MOVEMENT WILL CONTINUE INTO THE FUTURE UNTIL TOTAL FAILURE OCCURS, IS INDICATED BY THE FACT THAT MOVEMENT OF THE MASS AS A FUNCTION OF TIME IS LINEAR. A BERM OF A FREE-DRAINING MATERIAL SUCH AS SOUND SANDSTONE OR COMPARABLE MATERIAL AND OF SPECIFIED DIMENSIONS MUST BE CONSTRUCTED TO STABILIZE THE PRESENT SLIDE AND INCREASE THE SAFETY FACTOR. THE FACE OF THE BERM SHOULD BE PROTECTED WITH A RIP RAP BLANKET MEASURING 2 FEET IN THICKNESS AND EXTENDING SEVERAL FEET UPSTREAM AND DOWNSTREAM FROM THE SLIDE AREA IN ORDER TO PREVENT EROSION. TO ACCOMONDATE THE BERM AND TO MAINTAIN THE PRESENT CROSSSECTIONAL AREA OF THE CHANNEL, A PARTIAL CHANNEL CHANGE WILL BE NECESSARY. THE CUT SECTION OF THE CHANNEL SHOULD PARALLEL THE TOW OF THE BERM. THE DIMENSIONS OF THE PRESENT EMBANKMENT SLOPE SHOULD BE DECREASED. AN EARLIER CONSTRUCTED DRAINAGE SYSTEM WILL NOT LET CAPTIVE WATER LOAD AND WEAKEN THE EMBANKMENT IN THE FUTURE. THE HIGHWAY SHOULD NOT BE RELOCATED CLOSER TO THE CLIFF SINCE IT WOULD INVOLVE NEW CUTS INTO THE SAME SHALE FORMATION WHICH IS CONTIGUOUS TO THE BASE OF THE OLD SLIDE. SLOPE INDICATOR WELLS AT THE SITE SHOULD BE FULLY PROTECTED DURING RECONSTRUCTION AND DATA FROM THESE COULD BE USED TO EVALUATE THE SHORT- AND LONG-TERM EFFECTIVENESS OF THE PROPOSED PLAN. THE LOCATION OF THE UNSTABLE EMBANKMENT, THE TOPOGRAPHY AND THE GEOLOGY ARE DESCRIBED. FIELD AND LABORATORY INVESTIGATIONS ON SOILS ARE DETAILED. THE FAILURE MODE OF UNSTABLE EMBANKMENT, CALCULATED IN-PLACE STRENGTH PARAMETERS, AND REMEDIAL STABILITY ANALYSES ARE REVIEWED.

Media Info

  • Features: Figures; Tables;
  • Pagination: 8 p.
  • Serial:
    • Issue Number: 334

Subject/Index Terms

Filing Info

  • Accession Number: 00236481
  • Record Type: Publication
  • Files: TRIS, STATEDOT
  • Created Date: Sep 28 1973 12:00AM