13.5.2 Repair plan

In August 2004，the repair work of Dongjiadu section of Line 4 was restarted.After comparing the method of the in⁃situ repair and rerouting scheme，the in⁃situ repair scheme was finally adopted.After overcoming a series of technical problems such as the 65 m ultra⁃deep underground continuous wall，38 m ultra⁃deep underground obstacle clearing，ultra⁃deep foundation reinforcement in complex strata，ultra⁃deep confined water dewatering，41 m ultra⁃deep foundation pit excavation，tunnel pumping cleanup，large section freezing dug，the Dongjiadu section of Shanghai Line 4 was re⁃opened on July 9th，2007.

Both east and west bulkhead were built by using freezing method as cut⁃off wall.After the debris in the tunnel were removed，R.C.bulkhead was built to protect the unaffected tunnels from the cut and cover recovery works（as shown in Figure 13.13）.

Figure 13.13 In⁃situ repair scheme of dongjiadu section of line 4