Geotechnical

GEOTECHNICAL

Penny Farthing’s Geotechnical division was established in 2006 with the first contract in Olifantskop Pass in the Eastern cape. Since the geotechnical division has a very well renowned slope stabilisation- and lateral support reputation. We are vastly experienced in rockfall protection and lateral support e.g. drapery works, catch fences, debris fences, gabion installations, soil nails/rock bolt installations, shotcrete, grout, etc. The past years the Geotechnical division has achieved many partnerships, mutual beneficial affiliations and well-established relationships with suppliers. See in our award section the awards received from Geobrugg for installation of catch fences and debris slide fences, including best contracts award.

Slopes Repairs - RRM

Identified areas where the natural structure of an embankment or road-side structure has been impaired requires repair. The groundwork is prepared before-hand. All subsoil drains are installed to prevent the reoccurrence of the slip.

Slope Stabilisation

Stabilisation or securing slopes from loose and falling rocks, soil, debris by means of drapery and anchors. Removal of alien plants on slopes/mountains are one of the causes of instability. Thorough consideration with regard to the surrounding vegetation is given before any drapery or anchor work is done.

Lateral Support

Stabilisation or securing of loose rocks and soil by means of gunite and anchors. Problematic areas usually also occur when gabions and retaining walls has deteriorated, thus new structures are required.

Catch Fences

Stabilise slopes to prevent debris from higher up in the mountains to reach expensive structures ea. roads or buildings.

Debris and Slide Fences

Stabilization of slopes from falling debris and landslides, thus preventing damage to expensive structures. This product has a greater positive impact on the surrounding environment as nearly none of the protected vegetation will be harmed in the process.

Gunite

Stabilisation of excavated and problematic areas. Similar to lateral support the excavations and problematic areas are secured with gunite and anchors.

Soil Nails and Rock Anchors

Stabilization of slopes, loose rocks and anchoring of gabions. The installation of soil nails and rock anchors are used to anchor loose and unstable rocks. Stability work is done to fasten drapery work, anchorage in gunite applications and the anchoring of gabions.

Sewer Concrete Erosion Protection

Application of sewpercoat to new and/or eroded concrete surfaces entails cleaning and protecting the sewer chambers, pipes, manholes and channels against acidy deuteriations, by means of applying 15mm to 50mm thick layers of sewpercoat. There is no sentimental impact. The sewpercoat enhances the life span of the structures and surrounding area, preventing deuteriations.

RECENT PROJECTS

2011 to 2014

Koornfontein Coal Mine (Blinkpan)

This designed decline box-cut has a life of around 20 years, therefore a designed stabilisation of the vertical rock faces and horizontal benches was done by Rock Mechanical Engineers, this being rockbolting, meshing and lacing along with sprayed concrete. The support work was carried out as the excavation of the box-cut proceeded, with a final depth of 40m.

Strict safety measures had to be implemented at all times.

Trappieshoogte

As in one of our previous contracts the brief was to stabilise the rock mountain face against any further rock-falls, this is done by installing rockbolts in strategic positions and installing specialised rock-fall drapery mesh. A further protection method is the installation of catch fences to provide barriers for any loose falling rock releasing from higher places on the mountain face. The work has to be carried out using abseilers working at heights, once again high safety measures are put in place.

PRASA

The purpose of the designed lateral support on this project was to prevent slippage of existing earth embankment going on to the rail tracks, the advantage here of using sprayed concrete as opposed to other methods was access due to the overhead live electrical wires and limited access to the work face from street level. The combination of self-drilling anchors and a mesh reinforced gunite lining was used for the installation of the support work.

Kasese (Uganda)

This project involved the drilling, blasting, rockbolting and guniting of a 200 meter long intake tunnel. The contract was successfully completed within the allowable programme. Penny Farthing was recommended for this project by a Norwegian civil contractor who Penny Farthing had previously worked on a project within Mozambique.

Sir Lowry’s Pass

Penny Farthing were awarded the contract to provide rock-fall protection to various sections of the pass. Our brief was to install both mesh netting along with rock-bolts, as well as catch fences. The work was carried out at great heights and Penny Farthing used innovative access and drilling solutions to complete the works, while taking into consideration both the environmental impact and the busy traffic flow of this infamous pass.

Kwa-Kopi Pass

Due to recent dangerous rock-falls, this pass needed rock-fall support work done urgently at great heights. Penny Farthing were able to provide this service using specially fabricated working platforms to allow drilling of up to 12m long bolts to be installed. This method proved successful and the project is due for completion by the end of 2014.

Teekloof Pass

Certain section of the outside lane on this pass started showing signs of slipping. Penny Farthing were appointed by the roads contractor to provide lateral support to the inside lane, while the outside lane was being re-done. This entailed working in very restricted areas, but with innovative access platforms and plant they were able to overcome this problem.

N3 – MOOI RIVER

Existing embankments adjacent to the N3 Toll road near Mooi River were made up of a composite that when exposed to air and water they would start to disintegrate and fall onto the highway. Penny Farthing carried out the application of a fibre reinforced gunite lining to provide erosion protection.

Gateway Umhlanga

Penny Farthing were contracted by a piling company (VNA Piling) to carry out the reinforced gunite infilling between piles in order to complete the designed lateral support for basement parking to this office complex.

Kakamas Water Channel

The original design of this canal was the placing of no fine concrete using a sliding formwork set-up. However this proved to be impractical and an alternative design using rock-bolting and sprayed concrete was offered and approved. The contract was behind schedule at that time, but adopting this method allowed the contractor to catch up on its original programme.

Zimplats Platinum Mine (Zimbabewe)

R.O.M.(raw ore silos) that have been in use for over ten years have suffered fatigue in the constant loading and off-loading of the ore, to such an extent that the existing reinforcing was being exposed and a possible structural failure taking place. The first step in this rehabilitation was to reinstate the silo walls back to original profile and replacing of any missing reinforcement.

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