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Stabilizarea pantelor - Little Orme 2019

Limestone block wrapped in Geobrugg SPIDER® mesh

Stabilizarea pantelor - Little Orme 2019

This rock endangered people and infrastructure underneath

Stabilizarea pantelor - Little Orme 2019

Limestone blocks wrapped in mesh, Llandudno bay in the background

Stabilizarea pantelor - Little Orme 2019

Geobrugg SPIDER® mesh joining detail and contouring rope

Stabilizarea pantelor - Little Orme 2019

From road level looking up to the limestone blocks held securely with SPIDER® mesh

Stabilizarea pantelor - Little Orme 2019

Boundary ropes, Geobrugg P33/40 Spike plates and SPIDER® mesh

Stabilizarea pantelor - Little Orme 2019

Looking from the West back to the blocks, showing boundary ropes, P33 plates and SPIDER® mesh

 

Anul instalării

2019

Situația inițială

Following the routine inspection of the rock face by Colin Jones Rock Engineering LTD it was noted that a few blocks needed further inspection to ensure the safety of road and footpath users on the B5115 Colwyn Road. Daear Geo Consulting (DGC) was asked to undertake IRATA inspections of the blocks. In June 2018 DGC completed the field inspection and reported that the blocks pose a rockfall risk.

The consequences of the blocks failing are likely to be severe, with the blocks traveling at high velocity to the base of the slope with a very high likelihood of crashing through the masonry wall and onto the road or the hotel premises beyond.

The rockfall, therefore, posed a risk to users of the footpath that traverses the slope.

Geologie

The Little Orme is comprised of limestone with sub-horizontal bedding planes.
The jointing is orthogonal, defining large blocks. Generally, these joints are tight within the rock mass, however, due to weathering and block movement, they are often dilated on the rock face.

The limestone is made up of individual beds of varying composition, with a resulting variation in strength and resistance to weathering. As such the exposed faces display evidence of differential weathering rates. Horizons which are more prone to weathering will undermine overlying beds.

Over time the limestone blocks above will become unstable and will begin to topple forward, resulting in natural joints opening further. Eventually, the blocks will be displaced, and the process will start again.

Descriere

From the Daear Geo Consulting's assessment, three options were possible, removal of the blocks, stabilisation of the blocks or protection of infrastructure. Between DGC and Geobrugg it was agreed that the best solution would be to stabilise the blocks. Geobruggs SPIDER® ONLINE-TOOL was used to model the blocks and to confirm the requirements of bolt spacing and bolt length along with confirmation of the mesh type.

Geotechnical specialists Colin Jones (Rock Engineering) LTD decided upon a safe system of work, methodology, and equipment to undertake the site works. Using 25 mm bar into a 42 mm diameter drilled hole secured with resin capsules. The anchor bar depth was between 2.5 and 3 m into competent limestone. Drilling of all seven bolts was undertaken with handheld drill rig.

Client

North Wales Wildlife Trust

Antreprenor

Colin Jones (Rock Engineering) LTD

Obiect protejat

Road, Clădire, infrastructura turistică

Protecţie împotriva coroziunii

GEOBRUGG SUPERCOATING

Tehnologie

Daear Geo Consulting

Contactul dvs. local

Kevin H. Coyle
 

Kevin H. Coyle

Regional Manager Northeast

Natural Hazards
Inginerie hidraulică
Geobrugg North America, LLC,3 Beaudet Terr,Columbia CT 06237 / Statele Unite Regional Manager Northeast

E-mail

Saleh Feidi
 

Saleh Feidi

Regional Manager California

Natural Hazards
Inginerie hidraulică
Geobrugg North America, LLC,8921 Emperor Ave.,San Gabriel, California 91775 / Statele Unite Regional Manager California

E-mail

John Kalejta
 

John Kalejta

Regional Manager Central US

Natural Hazards
Inginerie hidraulică
Geobrugg North America, LLC,3215 67th Avenue Pl,Greeley CO 80634 / Statele Unite Regional Manager Central US

E-mail

Bob Lyne
 

Bob Lyne

Regional Manager Southeast

Natural Hazards
Inginerie hidraulică
Geobrugg North America, LLC,8004 Windspray Drive,Summerfield NC 27358 / Statele Unite Regional Manager Southeast

E-mail

Pierce Runnels, Civil Engineer
   

Pierce Runnels

General Manager Geobrugg North America

Natural Hazards
Geobrugg North America, LLC,22 Centro Algodones , Civil Engineer General Manager Geobrugg North America

E-mail

Tim Shevlin
 

Tim Shevlin

Sales Director

Natural Hazards
Geobrugg North America, LLC,Salem OR 97302 / Statele Unite Sales Director

E-mail