Abstract
The paper presents the design, development, and calibration of a soil contact pressure transducer, based on the null method. Air pressure regulated in a tightly controlled PID loop balances the output of a strain gage bridge bonded to the sensing element. This action maintains the sensing element in an undeflected state. The result is that the membrane does not interact with the surrounding soil, and errors due to arching are eliminated. In theory, the air pressure required to keep the sensing element in its undeflected state should be equal to the soil contact pressure applied at the soil boundary interface.
Calibration of the sensor reveals that its response is exactly as anticipated. The ratio between the required null pressure and applied soil pressure at the boundary interface is 1:1 and independent of soil type, soil stiffness, and load history. The paper presents calibration of the sensor for two very different sands, each at two significantly different levels of relative density.
The sensitivity of the sensor is a function of the control software. In its present version the sensor responds accurately to pressure imbalances of 0.3 kPa.
Keywords:
arching, calibration, null method, soil, soil pressure cell, soil-structure interaction
Paper ID: GTJ12484
DOI: 10.1520/GTJ12484
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Author Talesnick, M Affiliation Department of Civil and Environmental Engineering, Technion&emdash;Israel Institute of Technology, Haifa, Israel
Author Talesnick M
Title Measuring Soil Contact Pressure on a Solid Boundary and Quantifying Soil Arching
Symposium ,
Committee: on
