MEASUREMENTS OF FORCE IN THE CONCRETE COLUMN AND THE PRESSURE IN THE SOIL UNDER THE FOUNDATION SLAB OF A RESIDENTIAL BUILDING
Positioning of the building on the ground reinforced with columns utilizes the assumption of cooperation in the transfer of loads betewwn land and columns. Uniform transfer of loads to the ground and columns is intended to provided by the transmission layer. Measurements were carried out to determine the amount of force acquired by one of the selected columns and stresses in native soil located under the transmission layer. Measurement of compressive force in the concrete column with a diameter of 400 mm was made using a specially designed and constructed for this purpose measuring system. Set composed of a dynamometer, and the cooperating heads of the concrete column.
fig. View of the dynamometer at the bottom of a steel head crowning the lower section of the column in the concrete fig. View of the dynamometer after placin the shuttering tube of the upper section of the column, during the concreting of the upper section of the column
and after it’s concreting and covering.
Measurement of the pressure on native soil directly beneath the transmission layer, in the vicinity of the analyzed column was made using the vibrating wire earth pressure sensors model 4800 manufactured by Geokon. These sensors allow the observation of pressure changes in the soil by measuring the change in pressure of the hydraulic fluid in the measuring chamber. Pressure change in the sensor is proportional to the change of stress in the ground.
fig. Measurement field (100x100x20cm) pressure in the soil (in the middle visible pressure sensor)
The system performs the following measurements:
- – force in the selected concrete column,
- – strain (pressure) in the ground at two locations in the vicinity of the analyzed column,
- – the temperature in the native soil, in the transmission layer, in the concrete slab and in the air,
- – air preassure.