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GEOTECHNICAL SLOPE STABILISATION


The Abseil Access team are specialists in using rope access systems for stabilisation work on hazardous and difficult-to-access sites. Our team’s comprehensive knowledge of materials and techniques allows us to design the best and most cost-effective solution for any situation, regardless of the geological environment.

Working with local and national government transport bodies is when we come into our own, having completed projects on some of the most dangerous sections of highway throughout New Zealand. These include the Manawatu Gorge, the Otira Viaduct and Gorge, Nevis Bluff, Rocks Road, and the Lindis Pass hHighway. Abseil Access is also a preferred contractor of Kiwirail and has stabilised escarpments, cuttings and tunnel portals nationwide.

Our team are at home in New Zealand’s national parks and have performed geotechnical work on the Hooker Valley Track in Mount Cook National Park and the access track to Westland’s Fox Glacier.

SCALING AND BLOCK REMOVAL


Our Drill & Blast team has 20 years of experience removing, shaping, and re-profiling countless rock faces across the country. As scaling work is an often vital part of most geotechnical projects, our safety systems and risk analysis procedures have been internally perfected over decades to mitigate the risk of hazardous environments. In situations where wildlife may be at risk, we can work with our conservation team to minimise the impact and relocate animals if need be.

We are specialists in micro-blasting and use exact amounts of explosives to produce accurate fragmentation and minimal fly rock. When this needs to occur over a road or access way, we have people and traffic management procedures that can be put in place to mitigate the impact on the public.

Our services include:



  • Hand and Rope Scaling
  • ‘Airbag’ Jacking
  • Expanding Cement Grouts
  • Removal of Unstable Rock Features and Cliffs using High Explosives under EPA Class 1.1 and Nonex (Low Explosives) under EPA class 1.4.
  • Public Safety Management
  • Environmental Management
  • Clearing and Disposing of the Blast Debris

DRILL AND ANCHOR


Anchored slope stabilisation is the backbone of Abseil Access’ geotechnical arsenal. Our knowledge of rock types and sites allows us to select machinery and resources to complete the project safely and efficiently. Our fleet of hydraulic and pneumatically powered drill rigs can be adapted to run at ground level, in restricted areas, and to work in high altitude environments. We also can assist clients and consultancies with design and construction advice to complete external projects. In addition, Abseil Access can provide Geotechnical CPEng design services from resource consent to practical completion. This excludes the requirement for an external consultancy – saving in cost and time.

When employing our services, our engineering team will conduct an initial site investigation to analyse the area comprehensively and then design a strategic anchor pattern to make the rockface as stable as possible. Our geotechnical site crews will then use various access and drilling methods to create a stable borehole with the desired diameter and length. Once the holes are filled with cement, our team will insert the anchor and cap it with an anchor block. When combined with other slope stabilisation techniques, rock anchors can keep a rockface secure for decades. With our expertise in rope access, we can secure even the most inaccessible location.

Drill and anchor services include:



  • Cost-effective Methods for Securing and Stabilising Slopes
  • Installation of Soil Nail Bars in Soft and Unstable Ground
  • Increasing the Strength of the Slope with the Install of Hollow Self-drilling Anchor Bars Using High-pressure Grout
  • Installation of Glass Fibre Solid Bar From 25mm Through to 40mm Diameter
  • Installation of Single-Strand Steel Tendons from 16mm to 40mm Diameter
  • Installation of Cable Strand Anchors

ACTIVE ROCKFALL MESH


Abseil Access deploy rockfall mesh as the primary method to minimalise and control the impact of falling debris. Drape mesh systems can be deployed in a wide range of locations, including behind houses, above roads, and along railway tracks. Our team can deploy this affordable, durable slope stabilisation system using various specialist access methods, including rope access, scaffolding, or helicopter.

We work with leading suppliers to offer a comprehensive product range so you can choose a system that will suit the physical characteristics, needs and requirements. We install active and passive wire mesh systems, including GeoFabrics PVC coated double twist mesh, MacMatR, HEA panels, and PVC coated cable reinforced HR netting.

In the rare situations when a rockfall mesh is not a viable option, our geotechnical team can install catch fences, barriers and attenuators to suit your situation.




  • Installation of Geobrugg High Tensile Tecco and Deltax Mesh
  • Installation of Maccaferri Geofabrics PVC Galmac Double Twist, HR30 Cable Reinforced Mesh and MacMatR
  • Actively Pinned Rockfall Mesh
  • Rockfall Control Drapes and Attenuation Chutes
  • Rockfall Catch Fences from 100kJ to 8000kJ
  • Debris Flow Fences

SHOTCRETE & SOIL NAIL


To mitigate erosion and stabilise unreachable rock formations, Abseil Access’s geotechnical team can use a variety of shotcrete solutions. The critical advantage of shotcrete is that it can be used in inaccessible areas, including sheer vertical or overhead surfaces where other concrete substances can not.

Once the shotcrete dries, our team can further reinforce the rock formation using a combination of steel rods, steel mesh or fibres.

Our services include:




  • Forta-Ferro Synthetic Fibre-reinforced Shotcrete
  • Steel Fibre Re-enforced Shotcrete
  • Steel Grid Shotcrete Walls
  • Rope Access Shotcrete
  • Shotcrete Repairs to Façades
  • Retaining Wall Solutions
  • Soil Nails & Anchor Installation

PROJECT EXAMPLES

BLACKROCK SLOPE STABILISATION

In Blackrock Road, Wellington, the loose slope behind two residential properties had experienced several slips and required a shotcrete wall solution to secure the bank.

The repair of the slope consisted of inserting 17 anchors to a depth of 5m, then applying double-layered galvanised mesh to reinforce the anchors. Once this was secure a 120mm layer of shotcrete was applied to the face of the slope to prevent any further slips. The job was finished with the addition of new fences to comply with building consent requirements.

SLOPE STABILISATION IN RESIDENTIAL AREA

Wellington City Council engaged AA to assist after a recent slip resulted in an exposed slope, putting residents in the property below at risk.

Our team used various stabilisation methods, including 39 anchors driven up 6m into the rock, installing rockfall fencing at the top and bottom of the slope, hydroseeding and installing rockfall mesh. The project was completed within budget, fulfilling all QA and safety requirements of the client and the consultant.

TAWA SLOPE STABILISATION

A slip above the Main Road in Tawa posed a threat to traffic. Abseil Access was awarded the project to install 53 rock bolts with a reinforced rockfall mesh to prevent further erosion. A purpose-built scaffold was constructed to work with a traffic deviation to reduce traffic disruption to a minimum. The anchors were installed on the slip and into the rock at 2.5m high by 3m wide spacing and up to 6m deep with 100mm diameter holes. A timber water stop wall was then installed along the top of the site to divert rainwater away from the slip face. Finally, the area was covered with a layer of erosion control mesh reinforced with wire ropes. The works were completed on time within the 6-week timeframe and conformed with all the Engineers specifications and quality requirements.

KIWIL RAIL STABILISATION

Abseil Access was awarded the project to stabilise five ignimbrite bluffs adjacent to the NIMT rail corridor. A modified hi-rail excavator and a rotary telehandler allowed us to vacate the rail corridor rapidly, allowing trains to pass and avoid disruptions to the train schedule.

The tendons used in the project were a Glass-Fibre Reinforced Plastic (GRP) type of 32mm and 38mm diameters. This provided the client with minimal corrosion issues and a less hazardous material to handle for Abseil Access personnel.