Tunneling
Why microfine cement grouting in tunnel
Grouting is a common technique used in tunneling to improve the stability and water tightness of the surrounding rock and soil. Grouting involves injecting a fluid material, such as cement grout, into the cracks, fissures and joints of the rock mass to fill them and create a solidified mass. However, not all cement grouts are suitable for grouting in tunneling, as they may have limitations in terms of penetrability, strength and durability. This is where microfine cement grout comes in.
Microfine cement grout is a type of cement grout that has a very fine particle size and a high specific surface area. It can penetrate into fine sands or microcracks in rock and concrete that ordinary cement grouts cannot reach. It also has excellent permeability, strength and durability properties as a grout. Kangjing provide kinds of grade with different particle size depends on the different site condition, the customized formulas are available accordingly.
Different grouting methods
Grouting in tunneling is usually carried out to reduce water inflow to tunnels and underground excavations, which can cause problems such as erosion, corrosion, flooding and instability. Grouting can also enhance the mechanical properties and behavior of the rock mass, such as stiffness, strength and deformation. Grouting can be done before or after the excavation of the tunnel, depending on the site conditions and design requirements.
Microfine cement grout is an ideal material for grouting in tunneling, as it can effectively seal the cracks, fissures and joints in the rock mass and prevent water seepage. It can also improve the mechanical properties of the grouted rock mass, such as permeability, strength and durability. Microfine cement grout can be used for various types of grouting methods in tunneling, such as:
Pre-grouting
This is done before the excavation of the tunnel to stabilize and waterproof the rock mass ahead of the tunnel face. Pre-grouting can reduce the risk of water inflow during excavation and improve the quality of the tunnel lining.
Post-grouting
This is done after the excavation of the tunnel to fill any remaining voids or cracks in the rock mass behind the tunnel lining. Post-grouting can increase the load-bearing capacity and durability of the tunnel structure.
Contact grouting
This is done between the tunnel lining and the rock mass to fill any gaps or cavities that may have formed during excavation or lining installation. Contact grouting can improve the contact pressure and bond strength between the lining and the rock mass.
Curtain grouting
This is done around the perimeter of the tunnel to create a continuous barrier of grout that prevents water from entering or leaving the tunnel. Curtain grouting can reduce the groundwater level and pressure around the tunnel and protect it from external influences.
Successful projects
Yanyuan Tunnel
This is the high-way tunnel with a length of 14 km (9.41 miles). Microfine cement grout was used for pre-grouting to seal water-bearing zones (Under construction)
Songshan Tunnel
This is a 7.9 km (4.95 miles) long high-way tunnel. Microfine cement grout was used for pre-grouting to stabilize and waterproof the rock mass (Completion in 2021)
Dalian Tunnel
This is a 5.1 km (3.19 miles) long subsea road tunnel that connects several islands in Dalian. Microfine cement grout was used for post-grouting to fill any cracks or voids in the rock mass(Completion in 2023)
Microfine cement grout is a promising material for grouting in tunneling, as it can offer superior penetrability, strength and durability compared to ordinary cement grout. It can be used for various types of grouting methods in tunneling, such as pre-grouting, post-grouting, contact grouting and curtain grouting. However, it also has some challenges that need to be overcome by using additives, techniques and equipment. By doing so, microfine cement grout can achieve excellent results in terms of stability and water tightness of tunnels.
