PORT WORKS DESIGN MANUAL PART 3 Guide To - The University ...

50For monitoring of pore pressure during fill placement, the effect of tidal variation on thepiezometer readings should be checked in order to obtain the excess pore water pressure at agiven time and location. A piezometer may be installed outside the reclamation to providesimultaneous tidal data for excluding the tidal component on piezometer data taken within thereclamation (see Figure 9). The fill level at the piezometer location should also be recordedso that the measured excess pore water pressure can be compared with the total vertical stressincrease due to fill placement.5.2.2 SettlementSettlement is an important monitoring parameter for both drained and dredged reclamation.The magnitude and rate of settlement may be measured by means of settlement plates orextensometers. Settlement plates, installed either on the seabed, within the fill or at thesurface of the reclamation, measure the settlement by comparing the levels of the plates takenat different times, with a fixed datum level If settlement characteristics of individual subsoillayers are required, extensometers are more suitable. The settlement of individual subsoillayers can be determined by detecting the relative change in the vertical positions of thesteel or magnetic ring targets in the extensometers by a probe.5.2.3 Lateral DeformationLateral deformation can be measured by inclinometers. Lateral deformation data areparticularly useful during fill placement in a drained reclamation, as analysis of the data trendcan reveal early signs of instability in the sub-soil.In monitoring reclamation, an inclinometer is usually combined with an extensometer to forman inclmometer-extensometer composite installed in a pre-drilled hole. The fill level at andaround the instruments should be recorded simultaneously when taking the readings.5.3 Monitoring for Drained ReclamationReliable monitoring data is necessary for:• Monitoring of stability for drained reclamation.• Verification of predicted settlement.