Tunnel Support Systems Flashcards
1
Q
Advantages of polyester resin
A
Quick installation Sets quickly (1-30mins) Can possibly use two resins with different setting times Very high holding power Good protection against bolt corrosion Easy to install
2
Q
Disadvantages of polyester resin
A
High cost Limited shelf life (12 months) Vapours toxic to skin and eyes Mechanical properties decrease with increased temperature Setting time varies with temperature Flammable
3
Q
Advantages of cement grout
A
Low cost
High holding power
Good protection against bolt corrosion
4
Q
Disadvantages of cement grout
A
Takes longer to install
Slow setting time
Difficult to install in holes drilled upwards
Lack of control over grout quality (segregation) and anchor quality when end portion of hole not full)
5
Q
Equation for support pressure
A
P = P(pull-out)/S(c).S(l)
6
Q
What is the optimum angle for the bolts in order to minimise T
for a set value of Fs?
A
tanα = Fs.cotφ
