ABSTRACT
The first operating segment (Minimum Operating Segment 1, referred to as “MOS-1”) of the Los Angeles Metro became operational in 1993. This 4.4 mile (7 km) heavy rail line from Union Station to downtown forms the backbone of the city’s evolving subway system. During the construction of the second and third Minimum Operating Segments of the Los Angeles Metro (MOS-2 and MOS-3, also referred to as “Segment 2” and “Segment 3”, respectively), compensation and chemical grouting were performed to control settlements attributable to tunneling equipment, means and methods, and ground conditions. The soil grouting was used to modify the in situ materials before tunneling, to replace ground lost during and immediately behind shield tunnel excavation, and to improve ground behavior. This paper contains details of the procedures used, and the performance achieved in terms of effectiveness in controlling surface settlement.
