Cost overruns and tight timelines are a common thread for tunneling projects, especially when it comes to public transportation and infrastructure projects. Our full range of solutions contribute to efficient tunneling construction for a variety of project requirements. From concrete admixtures and shotcrete to waterproofing membranes and injections, Sika tunneling technology stands up to the highest quality standards around the globe.
Global Tunnel Construction Output by Use¹
¹Source: International Tunneling Association (ITA), Tunnel Market Survey 2016.
1. Concrete Solutions
Reliable and Durable Concrete – Key to Any Tunneling Project
Sika offers a fully integrated product range when it comes to concrete solutions for tunneling projects. For decades, Sika is involved on the most challenging and largest tunneling projects on the globe. From high durability concrete for efficient shaft linings to high strength road slabs, we offer the products that solve nearly every concrete challenge.
Fast construction of safe and durable concrete structures is no longer a difficult task with Sika admixture technologies. Good pumpability, flow and compaction, followed by high early strength, then low permeability are the key characteristics for a good tunnel lining concrete.
High early strengths achieved with SikaRapid® technology
In order to reduce cycle times in underground operations, high early strengths are needed to ensure the lining can be demolded and precast elements can be moved, transported, and installed safely.
Extended workability times produced using Sika® ViscoCrete® & Sika® ViscoFlow® technology
In many situations, extending the workability time of the concrete is essential in tunneling applications, especially for pumped concrete where the transport distances and temperatures can be challenging factors in maintaining the required workability.
Good pumpability with SikaPump®
This pumping agent reduces friction resistance and wear in the pipes and in the pump, allowing increased volume output. Initially it is also used to produce a lubricant mix to coat the internal walls of the pipe with a high-fines layer and allow easy pumping, right from the start of the concreting operations.
In the hardened concrete, high mechanical properties are achieved by using SikaFiber® in the mix.
For many areas of structural concrete the resistance against percussive or striking impact, plus the toughness and flexural strength of the concrete itself, can be very significantly improved by the use of these Sika structural fibers.
High flow and workability with Sika® ViscoCrete® technology
An efficient way of quickly and easily placing concrete is the use of so-called self-compacting concrete. With the right Sika mix design, this is able to flow under its own weight, completely filling formwork and achieving full compaction without vibration, even around heavily congested reinforcement.
In tunnel segment production, high early strengths for rapid demolding, followed by the highest requirements with regards to performance and durability have to be fulfilled.
High early strengths achieved with SikaRapid® technology
In order to reduce cycle times in underground operations high early strengths are needed to ensure the elements can be demolded, moved or put under load as quickly as possible.
In hardened concrete, fire resistance can be achieved by using SikaFiber® in the mix.
For many applications of precast lining, fire resistance is provided by the use of synthetic microfibers. Sika microfibers have been tested and certified by independent bodies and are well referenced for such application in many projects around the world.
2. Shotcrete and Equipment
Speed Up Excavation Progress with Sika Shotcrete Technology
In cycle shotcreting is key for rapid tunneling excavation and fast cycle times in tunnels around the globe. We offer fully integrated solutions for wet and dry shotcrete along with a range of shotcrete equipment for all applications.
Shotcrete is ideal for slope stabilization, especially when dealing with steep slopes and pit wall angles, in order to protect men and machinery in portals, galleries and on ramps.
Extended slump retention achieved with Sika® ViscoCrete® SC technology
Depending on the location and the complexity of the project, long haulage distances can require extended slump life of the concrete and in all manner of environmental conditions.
Rapid early strength development of the shotcrete is critical in order to enable short cycle times and ensure efficient rates of progress in tunneling.
High early strengths achieved using Sigunit® accelerators
Early setting of the shotcrete lining is critical in order to enable rapid underground development with short cycle times.
Sika Aliva® is a market leader when it comes to shotcrete equipment for both wet and dry spray applications. The equipment is especially designed for operations where access is difficult and small, equipment is of use due to smaller drift diameters.
Sika provides support from pre-testing, right through with continuous on-site support, to the completion of operations, in order to realize ongoing efficiencies.
Pre-testing and raw material qualification
Sika has developed unique testing equipment known as “MiniShot” where local raw materials (e.g. different binders, accelerators, admixtures and additives, etc.) can all be quickly and reliably tested locally and efficiently to optimize shotcrete mix designs.
On site testing
After the pre-evaluation and mix selection of the shotcrete-system using the Sika MiniShot, the mix-design is tested under real conditions. The well trained Sika shotcrete teams will then implement the best cost performing solutions.
Safe application, consistent speeds and uninterrupted spraying are critical factors for efficient in cycle shotcreting. This is achieved with Sika support to master the sprayed concrete operations with efficient equipment, mix designs, admixtures and skilled operators.
Long-term Cost Savings with the Right System
Today, operators request a service life for underground structures of 100+ years. However, a lack of water tightness severely reduces the long-term durability of a tunnel, causing damage and requiring expensive repairs and operational downtime.
The key elements to minimize operation costs include selection of the most appropriate waterproofing solution with project specific design together with safe application. A waterproofing system typically amounts to a fraction of total constructions costs. The selection of a high quality waterproofing solution may save a large amount on future maintenance and repair costs during the tunnel's service life.
As the global leader in structural waterproofing, Sika has a complete and comprehensive range of solutions to meet specific and usually harsh project requirements on site - including highly flexible membrane systems, waterproofing concrete admixtures and more.
The “umbrella system” provides a cost effective solution, based on a full arch barrier in combination with a drainage system to keep the tunnel and its structure dry. This method is suitable for non-fully submerged tunnels.
Umbrella sheet membrane system with loose-laid synthetic sheet membranes
For more than 50 years, Sika’s loose-laid synthetic membranes have been the below ground waterproofing system of choice where high performance is required. This technology has been continually developed and the service life of Sika membranes remains unchallenged and their leading position is maintained by the most comprehensive materials testing.
Channeled system using drained channels with waterproofing mortars or sprayed membranes
The Sika FlexoDrain channel system collects water ingress and drains it in a controlled way. Waterproofing mortars or liquid applied membranes are easy-to-use to protect both large and small areas of concrete surfaces, and may be applied by hand or spray. They can provide good durability and a long service life in contact with fresh water. However with increasing salt and chemical content, this service life can be reduced and additional protection may be required.
The hydrostatic barrier system is formed to withstand permanent hydrostatic water pressure. Sika's high performing loose-laid sheet membrane including compartments and integrated backup system is applied as a single or double layer system.
Compartmentalized membrane system with integrated injection backup
For more than 50 years, Sika’s loose-laid synthetic, PVC or TPO-based membranes have been the below ground waterproofing system of choice where high performance is required. This technology has been continually developed. The service life of Sika membranes remains unchallenged with a leading position maintained by the most comprehensive materials testing.
Fully-bonded sheet membranes
An alternative evolution of Sika’s advanced polymeric membranes are these systems designed to form a full surface bond with the structural concrete. These Sika systems fulfill the highest durability as loose-laid membranes. This factor makes fully-bonded membranes cost-efficient due to its ease of application.
Sika "white box" concept with watertight concrete and joint sealing system
The integral waterproofing of concrete structures makes this a very convenient and attractive approach for contractors with Sika concrete admixtures and jointing systems. However, durability also depends on the ground conditions, and additional protection may be required with increasing salt and chemical attacks.
Ground Consolidation, Stabilization and Waterstopping
Sika offers an extensive range of injection resin technologies for all types of applications. Uncontrolled geology below ground represents a major issue in tunneling and mining operations all around the world. Uncontrolled water ingress can cause severe problems and impact on daily operations. Sika’s over 100 years of experience and know-how in tunnel waterproofing help you address challenging ground conditions.
Water inrush in tunnel structures represents a major hazard which hinders and delays excavation and drifting processes. Sika® PU-resin injection systems are a powerful solution to consolidate and stabilize the ground to prevent and/ or counter any water situations.
Cavity and void filling is used to consolidate the fractured strata and stabilize the ground to ensure a faster, safer development process. The fast-foaming Sika® Silicate based injection products have high expansion factors that can fill large cavities and voids in a safe way.
An efficient way to stabilize unconsolidated geological masses, fractured rock-strata or permeable soils is by using cementitious injection grouting materials. The SikaFix®-800 range provides excellent penetration and consolidation properties. These systems are based on specially-blended cements and micro-fine cements with Sika® admixtures that are used to adjust the viscosity and accelerate the material's setting and hardening.
Sika provides the full range of injection products and systems to fill, stabilize and consolidate the ground in different geological conditions. In situations where the ground has relatively low permeability, Sika® Acrylate based injection resins with their low viscosity, water-like consistency and penetration ability, will give superior performance over other chemical resins and cementitious grouting solutions.
The use of TBMs for tunnel construction in highly populated areas such as cities and urban areas is now well established. However, there is still an increased risk factor when dealing with fault zones and unconsolidated geology. Potential collapses and water inrush must all be avoided, as the potential cost of losing control during the tunneling process is very high. This risk can be safely mitigated by using Sika® pre-injection systems to consolidate and stabilize the ground ahead of the TBM.
Over-blasting represents a major issue when it comes to external ore-dilution in underground, high grade, narrow vein mines. This problem from frequent over-breaking of the roof and ribs of the excavated stope can be significantly reduced and controlled by stabilizing the production face with Sika® Silicate resin injection systems. The injection of the resin takes place before a new round is blasted.
Sika’s experience and know-how in tunnel waterproofing over 100 years help you address the daily challenges in tunnels. Sika experts provide assistance on site and in the laboratory to select the most suitable and cost-effective materials and methods. We also provide the necessary detailed documentation and training for successful product application.
5. Tunnel Boring Machines (TBM)
Increasing Use of Mechanized Tunneling
Tunnel boring machines are very advanced equipment used as an alternative to drilling and blasting through rock and conventional mechanical excavation in soft ground. Mechanized tunneling has become more important with the rapid growth and expansion of underground construction in recent years.
Sika provides a wide range of products designed specifically for use
with a variety of tunnel boring machines, throughout the whole tunnel excavation and
construction process. Sika TBM solutions include foams, polymers, additives, main drive sealants, tail seal sealants, injections, backfilling grouts, conveyor belt repair, admixtures for shotcrete or concrete segments, rotor machines and spray booms.
6. Dust Sealers
Don’t Get Lost in the Dust
In most tunneling environments, dust represents one of the highest health and safety concerns. Therefore, a lot of effort is put into reducing dust generation to an acceptable level, on a daily basis. Sika Dust Seal®-300 is a new product from Sika, that prevents dust particles going airborne and reduces dust generation over an extended time period. The product is fully bio-degradable and is diluted with water prior to application.
Dust generates all sort of problems, ranging from health and safety concerns due to reduced visibility and respiration issues to increased wear and tear of machinery and equipment and increased ventilation costs in underground workings. Sika Dust Seal-300 is designed to provide a safe, water based and environmental friendly alternative to current dust-sealing solutions.
The Sika Dust Seal®-300 is currently supplied as a concentrated liquid solution that can be diluted with water in order to be applied on underground and open pit ramps drifts, haul roads, strips, dumps and stockpiles. The product forms a crust-like sealing layer with the dust particles that will last for an extended period of time. Watering efforts can be reduced strongly.