Large-size Earth Pressure Cell

The main difference is the sensing area. A larger diaphragm averages stress over a wider zone, which helps when you’re dealing with gravelly soils, rockfill, or concreted interfaces where pressure can vary a lot from one point to the next. A standard cell might record a spike that isn’t really representative of the overall load on the structure.

Yes, but there’s a practical trade-off. In soft clay, a large cell still works fine and may actually be easier to bed in because it has more surface area to push against the soil. In gravel, the cell’s size helps bridge over the voids so you don’t get misleading readings from a single stone pressing on the diaphragm. You’ll want to match the cell diameter to the maximum particle size — a rule of thumb is at least 10 times the d85 of the material.

It depends on the application. For direct burial, you compact a thin layer of sand around the cell to ensure uniform contact, then backfill carefully. In a retaining wall or pile, the cell is often strapped to the rebar cage before concrete placement, with the sensitive face against the formwork. For concrete embedment, you might bolt the cell to a bracket that holds it flush with the form. The key is avoiding point loading — the cell needs full-face contact.

The cell puts out a millivolt-per-volt signal, so any datalogger that can read full-bridge strain gauge circuits will work. You’ll need a readout unit or logger that provides excitation (typically 2–5 V) and can measure the mV output. Kingmach cells are compatible with most common geotechnical dataloggers; we can provide wiring schematics for the specific model you’re using.

Kingmach ships each cell with a calibration certificate that shows the pressure-to-output relationship. For most projects, this factory calibration is sufficient. However, if the cell gets physically damaged during transport or installation, or if you suspect it’s been overloaded, it’s worth checking it with a known pressure before relying on the data. We can also re-calibrate cells if they’ve been in service for a long time.