RAMIFICATIONS OF ANTICIPATED GEOTECHNICAL CONDITIONS ON THE SR-710 TUNNEL

摘要

The extension of State Route 710 (SR-710) has been in the planning stages forrnover 40 years. To alleviate traffic congestion and to enhance air quality within thernLos Angeles County metropolitan area, the California Department of Transportationrn(Caltrans) and the Los Angeles County Metropolitan Transportation Authority (Metro)rnhave proposed a tunnel concept for extending SR-710. At over 15.2 m in diameterrn(50 feet) and 7.2 to 17.7 km in length (4.5 to 11 miles), the SR-710 Tunnel will bernone of the largest and longest highway tunnels in the world. Challenging geotechnicalrnconditions have been identified along the potential tunnel routes, including variablerngeotechnical conditions ranging from unconsolidated alluvium to strong granitic rocks,rnhigh groundwater pressures, active earthquake faults, significant seismic hazards, formationsrnwith a high potential for methane and hydrogen sulfide gas, and contaminatedrnsoils and groundwater associated with Superfund sites. These conditions will bernencountered in a heavily developed urban environment.rnThis paper discusses the results of a geotechnical study of the feasibility of thernpotential tunnel routes. Based on the favorable results of this study, the project isrnadvancing into more detailed engineering and environmental studies as part of thernCaltrans Project Approval/Environmental Documentation (PAED) process.