Abstract
This report explains the measurement devices and the method of analysis in the model test of arch dam.
1) In the test within elastic limit of model, mercury was adopted to represent water pressure in prototype by next reasons. a) Its density is large enough (13.6). b) It does not give any concentrated load to the model. c) Loading can be made very easily. d) Strain measurement on the upstream and downstream surfaces is possible by using mercury. Fig.15 shows the devices for mercury loading.
Deflection of the downstream surface is measured in the arch radius and arch tangent directions by dial gauges (scale 1/100, 1/200 and 1/1, 000mm). See Fig.16.
In the measurement of strain on the upstream and downstream surfaces, wire strain gauges (length: 8mm, width: 4mm, resistance: 120Ω) are used. Compensating gauges are attached to active gauges, because wire gauges are very sensitive for temperature. By those gauges 4 components can be measured at each point.(See Fig.17)
2) The method of analysis was established from measured strain and stress.
If the surface stress at the measuring point is in the state of plane stress, arch, cantilever, main and shearing stresses, produced in model by mercury, are presented by equations (5-3), (5-5), (5-6), and (5-7) respectively. The coefficients between model and prototype become δp=147 δm (in deflection) and δp=7.350δm (in stress).
As the stresses for dead load are not given by model test using mercury, they are calculated by the method of analysis in uncracked cantilver. Namely, after vertical thrust and bending moment by the dead load on elevation at measuring point are calculated by epuations (5-23) and (5-25), they are computed by next equations:
δV'D=ΣWe, n/An-Me, n/In·(Tn-lgn)...(downstream side)
δV'U=ΣWe, n/An-Me, n/In·lgn...(upstream side)
δV'D and V'U are the vertical stresses to normal for horizonta1 section. The values of measurement, on the other hand, are surface stresses of dam body. Therefore, V'D and V'U must be converted into surface stresses. The relation between vertical stress and surface stress becomes δV=δV' sec2φ'.φ'is given by equations (5-28), (5-32) and (5-33).
