Pressure [Soil]

 

Static Soil Pressure Cell - PL (& PT)

 

Description

A "PL" or "PT" sensor measures horizontal or vertical pressure in base and subgrade layers caused by environmental loads (moisture, temperature, settlement). A "XL" or "XT" sensor, mounted within the PL or PT sensor, respectively, is a thermistor necessary for temperature correction of the measured pressure. Data is automatically collected once every 15 minutes. The Lateral Soil Pressure (PL) and Vertical Soil Pressure (PT) sensors consist of two 6 inch (152 mm) diameter steel plates (welded together around their rims) connected by a steel tube to a vibrating wire sensor. The space between the plates and within the tube is filled with a liquid. The vibrating wire sensor responds to changes in pressure applied to the plates by the material in which the sensor is embedded.

 

Manufacturer

Geokon 4800E Earth Pressure Cell.

 

Location and Quantity

PL/PT sensors are embedded into the base and subgrade layers near the centerline of the roadway of both asphalt and PCC test cells.

 

There were originally 13 PL (&13 XL) and 53 PT (&53 XT) sensors located in 4 PCC, 6 hot-mix asphalt, and 1 aggregate surface MnROAD test cells. As test cells have been constructed, both new and "recycled" PL/PT sensors were installed.

 

Current Status

These sensors have performed well. Most PL or PT sensors have not been tested for functionality recently, therefore their status is unknown.

 

MnROAD Database Table

Data has been collected both manually and automatically during the life of each sensor. Data can be found in MnROAD database tables: MNR.PL_VALUES, MNR.XL_VALUES, MNR.PT_VALUES, MNR. XT_VALUES, FT_VALUES.