The Research On Construction Technology Of Existing Railwayunder The Complex Geology Condition About Double-Line Railway Tunnel

Additional second line of Guiyang-Kunming Railway is the national key railroad project. Zhanyi triple tunnel of Liupanshui is the key control engineering, which length is 12214m, because of its short construction time, the complex geological structure, the existing railway construction difficult. How to ensure the safety of tunnel construction and the existing line operation is the most important works, because the trigeminy tunnel imports stand under Guiyang-Kunming railway roadbed, the tunnel buries the depth is shallow, the soil texture is loose ,the traffic flow rate of the existing line is big .The triple tunnel entrance section DK300 +387 445 is located at landslide body of Ding-jia Village. Geological conditions in the region is the angle gravel soil, blocks of stone, artificial Spoil soil. This section is easy to collapse because the soil body is loose. The Tunnel depth is 3 ~ 6m .The triple Tunnel triple in the DK300 +419.12 beneath the existing Guiyang-Kunming line roadbed, the existing line is the circular curve R = 305m, the new line and existing line has the 35°38 ' angle, overlapping course is DK300 +419.12 = K311 +620.56. The tunnel construction is difficult because the elevation difference of two-line track surface is only 13.59m and the tunnel excavation arch away from the existing railway line is only 2.7m.The D-beam within the existing railway K311 +599 647.5 is used and the existing railway operating speed limited is 35km / h in order to even transmission train load preventing uneven settlement of the existing lines . The tunnel uses long pipe roof advance support, double-sidewalls guiding-hole is divided into nine subsurface construction. Supporting structure is adjusted timely through the data analysis of monitoring measurement. Secondary lining is constructed branch after the excavation of the tunnel ,the third lining concretes is constructed one time after secondary lining lined into the ring. The D-beam is demolited after the third lining concretes meet the design strength, then normal operation of the existing lines is restored.Double-sidewalls guiding-hole method whether to ensure the construction safety of new lines and the operation security of existing line is very important though D-beam reinforced the existing line and directional pipe roof advance support grouting, surface grouting and tunnel radial consolidation grouting. The purpose of the study is the safety supporting systems, reinforcement measures and excavation method whether to scientific and effective.