Case History

M25 Motorway | London, England

In March, 2003 Geotechnical Observations Ltd. and Mouchel Parkman Ltd began the investigation of a slope adjacent to the M25 motorway south of London, England. The investigation required 25 vertical inclinometers, which are read manually every week and 28 piezometers, which are data logged.

Movements have been detected at a depth of about 7 m, as shown in Figure 1. In early 2004, the rate of movement increased from about 0.2 mm per week to nearly 2 mm per week, in response to a notable increase in pore water pressures. Subsequently the rate of movement decreased to about 0.2 mm again. In preparation for any further increases in movement, a string of Geokon Vibrating Wire In-place Inclinometers [Model 6300] was installed along the shear plane, as shown in Figure 2. The string was then connected to a Campbell Scientific CR10X with GSM modem for the daily, remote downloading of data to GeO’s office for examination.

Special thanks to:
Geotechnical Observations [www.geo-observations.com] Mouchel Parkman [www.mouchelparkman.com] and the Highways Agency [www.highways.gov.uk] for sharing the results of this investigation.

For more information, please contact: GeokonNews »
or call: 1.603.448.1562

 M25 Motorway.

M25 Motorway. Image courtesy of Geotechnical Observations Limited.