GB1251220A - - Google Patents

Abstract

1,251,220. Measuring building settlement. SOIL MECHANICS Ltd. March 26, 1970 [Dec. 30, 1968], No. 61696/68. Headings G1M and G1N. The settlement of large buildings is monitored by a method using an apparatus comprising a measuring bar 2 rigidly-fixed to the foundation 5 of the building, a datum bar 8 rigidly fixed to ground 10 outside the settlement zone, a beam 1 fulcrumed at one end 6 on the datum bar 8 the other end resting on the measuring bar and a tiltmeter attached to the beam to sense any change in the level of the beam consequent upon settlement of the building. As described datum bar 8 grouted into a rock stratum 10 is centered by spider 12 in tube 10, filled with oil 11 to within a few feet of the ground surface to keep this part of the bar at a constant temperature. The datum bar 8 above the oil surface the whole measuring bar 2 and the beam 1 are made of a steel of low temperature coefficient of expansion. The beam 1 is supported on the top of the datum bar 8 on a steel ball 7 and at the top of the measuring bar 2 on a line of steel balls constituting a linear bearing. To limit rotation of the beam 1 about its longitudinal axis, projection 18 extends laterally and is supported on a stabilizing bar 19. The tiltmeter is preferably an "electrolevel" consisting of a bubble level containing an electrolyte in which electrodes are immersed. The electrodes are connected in a bridge circuit which is unbalanced as the bubble moves between the electrodes providing a signal to a terminal box 23 in housing 24.