Corina CASTILLO

Study on the influence of TBM operation on its behaviour in H&V shield.

Mitsutaka SUGIMOTO

A tunnel boring machine (TBM) is a machine with a circular cross section that can go through a variety of soils and is used to excavate tunnels. A H&V shield is a tunneling machine with two bodies instead of one, known as right and left body, in which the left body keeps a horizontal and vertical alignment, while the right body rotates around the left body. For this study, the data was that of a closed type shield (a type of TBM), which have the particularity of being able to go under groundwater.Also, an H&V shield has the advantage of constructing two tunnels at the same time, reducing time and budget.
The influence of a H&V shield operation on its behavior was studied, based on the numerical analysis with four different parameters. A computerized program gives us the results of how these parameters affect the distance reached, direction, velocity, etc�D of the machine. The parameters were: Copy Cutter Length (CCL) and Copy Cutter Range (CCT) which was analyzed using the Effective rate; Crease and Pitching Angle, analyzed by the Alpha value; Jack Force; and, finally, the ground stiffness defined by SPT-N value.
Of the four principal parameters that were analyzed for this study we can conclude as next:
1) The effective rate of the copy cutter length is important to reduce the friction generated because of the contact between the machine and the ground. This is important because the friction reduces the velocity. 
2) The Alpha value, which only affects the Right body, affects the pressure area due to the inclination. For this reason, a bigger Alpha value means bigger pressure on the tunneling machine, reducing the velocity too. 
3) A large jack force is required to increase the velocity. Also, the jack moment is effective for rotating the shield. 
4) The high ground stiffness actually helps the machine, permitting the rotation more easily, increasing the velocity ant therefore also the reached distance. 
These parameters have an influence on the H&V shield that should be considered in order to optimize the excavation work.