DESIGN OF A DIFFERENTIAL PORE PRESSURE MANOMETER AND ITS TIME LAG CHARACTERISTICS

A NEW DIFFERENTIAL PORE PRESSURE MANOMETER HAS BEEN DESIGNED WHICH CAN REGISTER SIMULTANEOUSLY THE DIFFERENCE OF PORE PRESSURE AT BASE AND ANY OTHER POINT INSIDE THE TRIAXIAL SOIL SPECIMEN. THE DESIGN CRITERIA OF THE ABOVE DEVICE HAVE BEEN DISCUSSED. THE DIFFERENTIAL PORE PRESSURE MANOMETER IS USEFUL FOR SATURATION BY BACK PRESSURE AND MEASUREMENT OF PORE PRESSURE IN THE TRIAXIAL SPECIMEN WHERE THERE IS NO CONTROL OF CELL PRESURE. EXPERIMENTS HAVE BEEN CARRIED OUT TO MEASURE TIME LAG IN PORE PRESSURE MEASUREMENT AT BASE AS WELL AS CENTRE OF THE SPECIMEN. EXPERIMENTAL RESULTS CONFIRM GIBSONS THEORETICAL ANALYSIS FOR TIME LAG IN BASE PORE PRESSURE MEASUREMENT. PORE PRESSURES IN THE CENTER OF THE SPECIMEN WERE MEASURED THROUGH A PLASTIC PROBE CONTAINING A FILTER TIP AT ITS END. SUITABILITY OF OTHER TYPES OF PROBE HAVE ALSO BEEN DISCUSSED. TIME LAG IN PORE PRESSURE MEASUREMENT THROUGH PROBE HAS BEEN COMPARED WITH THE THEORETICAL VALUE FOR PIEZOMETER BURIED IN SEMI-INFINITE SOIL. IT IS PREDICTED THAT IF THE DIMENSIONSLESS FACTOR IS GREATER THAN 1000, THE SPECIMEN MAY BE TREATED AS SEMI- INFINITE MEDIA WITH RESPECT TO THE PROBE. THE TEDIOUS DIFFERENTIAL EQUATION FOR TIME LAG HAS BEEN SOLVED NUMERICALLY BY SCHMIDTS METHOD AND SIMPLE EMPIRICAL FORMULAE HAVE BEEN OBTAINED FOR TIME LAG IN PORE PRESSURE MEASUREMENT AT BASE AS WELL AS MID-HEIGHT OF THE SPECIMEN. IN CLAYEY SOILS, THE PORE WATER HAS CONCENTRATION OF IONS. CONSEQUENTLY, OSMOTIC PRESSURE WILL COME INTO PLAY DURING PORE PRESSURE MEASUREMENT. SOURCE OF ERROR DUE TO ABOVE CAUSE AND REMEDIAL MEASURES HAVE BEEN DISCUSSED. IT WAS OBSERVED THAT THE FILTER TIP WAS OFTEN CHOKED. BACK PRESSURE WAS FOUND VERY EFFECTIVE IN REMOVAL OF CHOKING FROM THE FILTER TIP. VOLUME CHANGES IN PORE PRESSURE LOAD OF BISHOPS PORE PRESSURE APPARATUS HAVE BEEN MEASURED WITH CHANGES IN ATMOSPHERIC TEMPERATURE WHICH WERE FOUND TO BE OF CONSIDERABLE MAGNITUDE AND WOULD AFFECT THE PORE PRESSURE MEASUREMENT SUBSTANTIALLY. /AUTHOR/

  • Supplemental Notes:
    • Vol 8, Nos 1 & 2, PP 129-148
  • Corporate Authors:

    N/A

    ,   United States 
  • Authors:
    • Narain, J
    • SINGH, B
  • Publication Date: 0

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  • Accession Number: 00229120
  • Record Type: Publication
  • Source Agency: Crri Road Abstracts /India
  • Files: TRIS
  • Created Date: Aug 15 2004 1:49AM