Building a tunnel and creating holes in the mountains has a lot to do with human societies, from the establishment of primary caves for shelter to creation, to the construction of aqueducts at high depths (deep about 70 kilometers or more) were used to access water. Importance The construction of tunnels in the old days, so that experts in tunnel construction work in these civilizations have shown the growth of culture, and in particular the technical growth and economic potential of this society. Early civilizations quickly recognized the importance of tunnels as access to minerals and natural materials such as Flint because of their importance for life.Their application also included a wide range of gravel stones up to water transmissions or commuting trains. The military applications of tunnels, especially in order to increase escapement or ways to attack enemy footholds and forts, were another important aspect of the use of tunnels in the early civilizations.
With the onset of the industrial revolution, a huge transformation took place in the construction of tunnels, and the tunnels went for more durable construction for various uses, including road construction, railways, water transmissions, transmission of high-pressure urban cables, and so on.
Gradually, the need for high durability and high durability tunnels, especially in areas with loose soil, led the researchers to move towards products for the construction of these tunnels, which could provide the factors involved. First, steel and steel products to increase Tunnel strength went by which, given the time and level of facilities and technology, the low population density was a very suitable product to meet the needs of that timeHowever, with the growth of population and industry, and the increase in the level of use of other steel tunnels, disadvantages such as low useful life, activation of protective layers after tunnel deformation, lack of resistance in many soils such as lime soils, rust Corrosion, etc., was not needed. Researchers nowadays have come up with a more durable product with superior properties called Composites.
Installation in intermediate pilot tunnels in large tunnels at the time of drilling in weak rocks, pre-consolidation of rocks around the final section of the main tunnel and the rapid and rapid swapping of the pilot tunnel to the main cross-section.
• Temporary storage systems (due to the ease of drilling and cutting followed by these types of bars).
• Permanent preservative system (due to excellent resistance to corrosion and high life)
• Consolidation of rock mass and soil mass
• Maintenance system in road and rail tunnels
• Pre-consolidation of underground metro tunnels from the ground and drilling fast and secure tunnels on pre-tilled ground, with a convenient cutting of glass fiber reinforced bars (unlike steel ones) with any type of drilling system.
• Resistant to oxidation and rust
• Longitudinal tensile strength above steel (conventionally, at least 2 times)
• Minimum compressive strength of steel equivalent diameter• Lower specific gravity than steel (at least a quarter of steel)
• Possibility to use rock bolt or anchor in one piece without connecting with any length in pilot tunnels with width
• Less than the Rocket Bolt you want to install
• Possibility of using a mesh warp with a single piece and without overlapping along the perimeter (walls and ceilings, and even tunnel floors), by applying pressure on the walls and the tunnel roof, helping the tunnel self-reliance, installing the lattice, and applying the shutter.• Possibility of using as a lattice on the GFRP mesh by activating active pressure (ACTIVE) from the beginning and at the closest point to the tunnel chest
• Relatively elastic behavior to failure and residual resistance after failure.
• Resistor properties
• Lower elasticity and shear modulus (about 30% – 20% steel)
• Specific low weight (conventionally, 25% – 20% steel)
• Easy transportation and no need for heavy machinery to move
• Reduce the cost of completing the project
Installation steps of the proposed GFRP composite system:
• Installation of GFRP loop for the entire environment (walls and ceilings) around the tunnel, integrated, without overlapping, which is only portable and installed by two people. This type has its elastic and springy properties from the very beginning Installing the opposing force instead of the mass of rock around the tunnel (this installation will not last for 30-15 minutes).
• Placing the two end edges of the lattice with 12 mm diameter grooved fittings of the GFRP, in a single piece, without connecting, which is only portable and installed by two workers. This type of lattice (which will be installed immediately after installation) (in line with its elastic and spring-loaded GFRP, it employs an opposing force instead of a rock mass around the tunnel, and the spring force and force opposite For deformation, the rock mass is applied around the tunnel (this installation will also not last for 30-15 minutes).
• These two GFRP Latches are connected and easily installed by a triangular clamp with two grips at the base and a clamp at the top.
• Apply the first layer of the shutter core to the mesh of the mesh and the two lattice triangular edges of the lattice, which, due to the spring property and the pressure applied to the lattice set and its mass to the rock mass, can be easily implemented and have a higher resistance to the same types of steel Have.
• If necessary, the second layer of the mesh of the mesh on the lattice toes (located along the tunnel environment in half-meter intervals) is fitted with the same spring property and with ease and speed.
• Installing the third edge and triangle of LaTeX vertebrae between the mounting clamps for this edge, during less than half an hour.
• Apply Final Shotcrete
Technical justification for replacing the composite retainer system in place of the steel retaining system:
With regard to the benefits provided in this section, and in the light of similar international experience, the increase in the stability and safety of the tunnel, coupled with a reduction in the time and cost of implementation, will be guaranteed.
Advantages of the proposed GFRP system:
• Materials of GFRP type (at least a quarter of the weight of steel), and transport and install them easily and in the least amount of time with the lowest human and machine energy.• Due to the elastic and springy nature of the Wire Mesh and Lattice, the minimum displacement of the rock mass around the tunnel (also synchronized with the Wire Mesh and Lattice (GFRP) setup occurred from the very beginning as an Active Active Hold system Naturally, in this case, the crucibles in the rock mass have the least degree of rupture and opening, and the system of preserving the GFRP will have a significant role in the rock mass in self-restoration and its self-sustainability. Meanwhile, the rock mass with lower droplets Broken (and even unbroken in some directions in relation to the axis of the tunnel), more resistance to dynamical loads The show itself.
• The work speeds are remarkably high.
• Installing Wire Mesh and Latitude, especially in the ceiling, necessarily requires the necessary machines, such as a loader or an inevitable lift, which naturally increases the time and cost of work. The installation time of the two-layer mesh installation and the entire Latis component (without the implementation of the shutter-script) takes a total of less than two hours.
• The GFRP crew will actively activate force along the tunnel environment toward the rock mass, until it is applied to the rock mass, which, in addition to preventing the uncontrolled rupture of the rock mass, ensures greater resistance to the applied shutter. The possibility of instability and dropping up to the time of applying the shutter (especially in the upper arc of the tunnel) also significantly decreases in this preservation system.
• Due to the active presence of the GFRP retaining system set, based on actual instrumentation data (at least 4 stations of the three-point tensile meter and about 20 stations of convergence), and the behavior measurement, with the co-ordination and consultation of the consultants of the project and after To ensure the static and dynamic stability of the Hajiabad Water Transfer Tunnel, the possibility of removing concrete lining over the whole tunnel is completely documented and without the slightest risk.
Economic justification of the replacement of the composite retaining system instead of the steel retaining system:
The following are the economics of the undoubted use of a preserving system set). Its Grammar, Rock Bolt and Latit (GFRP in comparison with steel similar):
• Tensile strength is at least twice as high as steel (Rock bolts with a diameter of 1.4 times less than steel equivalent). For example, the use of rock drill bolts φ25 mm GFRP instead of φ25mm steel, with the same specifications and mechanical strength.
• Increasing the stability of the rock mass around the tunnel and the safety of the working environment inside the tunnel, taking into account the properties of the GFRP retaining system and the active nature of the active maintenance system. Lower weight (at least a quarter similar to steel), which will increase the safety and speed of work along with lower finished costs.
• Shipping costs to destination will be reduced by about 5.5 times.
• There is no need for a lift or a loader to install a weaver mesh and a lattice (removal of machinery costs).
• Increase work speed (decrease in fixed and current expired costs).
• Greater friction controversy between rock GFRP Bolt, compared to Rock Bolt Steel.