STUDY ON EFFECT OF PIEDMONT FAULT OF LISHAN MOUNTAIN ON XI'AN METRO LINTONG LINE

Based on the metro Lintong line passing through the active fault of Lishan Mountain on Xi'an metro Lintong line, the three-dimensional finite element model of metro tunnel-active fault-stratum was built. Deformation and stress characteristics of metro tunnel crossing the piedmont fault of Lishan Mountain, effect mechanism and key fortification positions of metro tunnel are revealed. The fortification range of the subway Lintong line crossing piedmont fault of Lishan Mountain is determined, and the corresponding measures for prevention and control are put forward. Research result shows that active fault ruptures caused bending deformation along the longitudinal metro tunnel. The tunnel can be divided into three deformation areas:stability section in the footwall, shear tension section in the fault zone and settlement section in the hanging wall. The vertical stratum stress near the fault zone decreases in the hanging wall and increases in the footwall. In addition, the contact pressure at the bottom of the tunnel decreases in the hanging wall and increases in the footwall. Vault contact pressure increases in the hanging wall and decreases in the footwall. And the top of tunnel is in compression at the hanging wall and in tension at the footwall. The bottom of tunnel was in tension at the hanging wall and in compression at the footwall. The shear scope of the tunnel remains unchanged with the variation of fault dislocation. The maximum shear force occurs at the intersection with the fault. Finally, it is confirmed that the fortification length of Lintong line across the fault is at least 80 m. The measures for prevention and control measures are put forward. The conclusions can be presented as the reference for the design and disease control of Xi'an LinTong Line passing through the piedmont active fault of Lishan Mountain.