Minnesota Department of Transportation

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Pressure in Soil

Staff member installing sensors

Pressure in Soil

Dynamic Soil Pressure Cell - PG

Description

A "PG" sensor measures vertical pressure in base and subgrade layers subjected to dynamic loads. The Dynamic Pressure Gauge (PG) is a pressure-sensing device consisting of two 6 inch (152 mm) diameter steel plates (welded together around their rims) connected to an electrical pressure transducer by a steel tube. The space between the plates and within the tube is filled with a liquid. The transducer responds to changes in pressure applied to the plates by the material in which the sensor is embedded.

Manufacturer

Geokon 3500 Dynamic Soil Pressure Cells with Ashkroft K1 Transducers.

Location and Quantity

PG sensors are embedded into the base and subgrade layers near the wheelpaths of both asphalt and PCC test cells.

There were originally 106 PG sensors located in 8 PCC and 7 hot-mix asphalt MnROAD test cells. As test cells were reconstructed, functioning PG sensors were removing and reinstalled into newer test cells.

Current Status

These sensors have performed well.

MnROAD Database Table

Data continues to be collected during various load response testing sessions, and some has been processed and loaded into the MnROAD database. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS. 

Dynamic Soil Pressure Cell - PK

Description

A "PK" sensor measures vertical pressure in base and subgrade layers subjected to dynamic loads.

Description

The Dynamic Pressure Gauge (PK) is a small diameter, soil stress cell consisting of a liquid-filled hollow steel cell approximately 50.8mm (2") in diameter and 12.7mm (.5") thick, with an electrical pressure transducer housed within the cell. The transducer responds to changes in pressure applied to the surface of the sensor by the material in which the sensor is embedded.

Manufacturer

Kulite model 0234 Soil Pressure Cell.

Location and Quantity

PK sensors are embedded into the base and subgrade layers near the wheelpaths of both asphalt and PCC test cells.

There were originally 66 PK sensors located in 4 PCC, 11 hot-mix asphalt, and 4 aggregate surface MnROAD test cells.

Current Status

These sensors have performed well. Recent status is unknown.

MnROAD Database Table

Data were collected during various load response testing sessions, and some has been processed and loaded into the MnROAD database. Data is located in database tables named: MNR.DYNAMIC_LOAD_TEST_VALUES and MNR.DYNAMIC_LOAD TEST DESCRIPTIONS.