Hydrostatic levelling cells

HLCs are high accuracy system designed to measure vertical movement and can accurately measure heave or settlement within a 500mm range.

System components include a reservoir, Hydrostatic Levelling Cells, tubing, cabling, deaired liquid, and a datalogger/PC.
The cells are connected into a circuit using liquid and air tubing, then filled with fluid via the reservoir.
One cell is assigned as the reference cell and is placed outside the zone of influence. 

When a structure experiences settlement or heave, the cells record a change in pressure. 
Pressure readings from monitoring cells are compared to the reference cell and a baseline to accurately calculate movement across the system.
The use of a reservoir and reference cell in this way eliminates factors that effect the whole system, such as changes in fluid level from evaporation.

HLCs are fully integrated with our web monitoring interface, Quickview. Data is streamed online within minutes from data acquisition, so that construction can be directly guided by the actual ground movement. 

The systems are supported by purpose-built software that provides easy-to-use graphical visualisation, automated reporting, and a robust alarm system that can send instant alerts if any set threshold is breached.

HLCs can be particularly useful in situations where conventional survey techniques are not feasible (e.g. basement monitoring).

GEO-Instruments have unparalleled experience with HLC systems, having installed several thousand sensors globally. Our largest system to date, used to control settlement and heave on a London based project, required 1700 cells.