12th International Symposium on District Heating and Cooling

The <strong>12th</strong> <strong>International</strong> <strong>Symposium</strong> on District Heating and Cooling,September 5 th to September 7 th , 2010, Tallinn, Estoniafind potential frost action damages. The inspectionswere documented with photos.3. RESULTS3.1 Test results from deformation of the pipe overtimeThe measured pipe deformations during the test periodturned out to be very small. The diagram in Fig. 13describes the measured changes in the casing sinceinstallation and average air temperatures during thetest period. All three displacement gauges were set tozero before the installation. The diagram shows thatthe casing of the test pipe during the installation wassqueezed out up to 0.5 mm at the three measurementpoints. The deformations in the casing are most likelycaused by the packing of the backfill surrounding thepipe.After the installation during the test period the resultsindicate that the upper side (violet curve in thediagram) of the test pipe casing have been pressed in0.2 mm. The side of the test pipe casing havesqueezed out approximately 0.1 mm. The under side(red curve) was squeezed out approximately 0.1 mmduring the period between the first and secondmeasurement results. During the rest of the test periodthe casing have been pressed back in 0.1 mm.It is to be observed that these measured changes arevery small relative to the test pipe casing diameter.Compared to the zero values in the laboratory themeasured changes are not more than 0.3 % relative tothe casing diameter.In Fig. 16 and 17 the diagrams show the vibrationvelocity (m/s) in the ground when a heavy lorry passover the test area at a speed of 40 km/h. The vibrationvelocity is calculated from the acceleration signal byintegration.The diagrams in Fig. 18 and 19 show the maximumamplitude of the acceleration in the ground as afunction of the speed of the lorry when it passes overthe test area in 20 km/h and 40 km/h, respectively themaximum vibration velocity as a function of the speedof the lorry.200 mm below surface, vehicle speed 40 km/hTime (s)Fig. 14 Vertical acceleration 200 mm below the roadsurface when a lorry passes at 40 km/h.600 mm below surface, vehicle speed 40 km/hmm0,90,80,70,60,50,40,30,20,10-1000 100 200 300 400Days since installationAverage temperatures (°C)Under SideUpper SideFig. 13 Average air temperatures and changes in casingat installation and during test period.3.2 Test results from instant deformation of thepipe and accelerations from traffic loadThe diagrams in Fig. 14 and 15 describe the vibrationsprocess at 200 mm, the same depth as the test pipe,and 600 mm below the road surface as acceleration(m/s2) in the ground when a heavy lorry pass over thetest area at a speed of 40 km/h.Side200-20-40-60-80Time (s)Fig. 15 Vertical acceleration 600 mm below the roadsurface when a lorry passes at 40 km/h.Velocity (mm/s)200 mm below surface, vehicle speed 40 km/hTime (s)Fig. 16 Vibration velocity 200 mm below the road surfacewhen lorry passes at 40 km/h.100