The 26km (16.2 mile) long Express Rail Link (XRL) Hong Kong section is a cross boundary transport infrastructure project, which will form part of the high speed rail services between Hong Kong and Guangzhou, China. As part of Contract 821, the Dragages-Bouygues JV constructed one of the largest tunnel intersections ever attempted in Hong Kong, a 24m (78.7 ft.) span adit forming a junction with the 22m (72 ft.) span, resulting in an effective span of 32m (105 ft.). The design for temporary support is presented including development of the geological model and implementing this into 2D and 3D numerical models. The construction sequence was fundamental in controlling stress re-distribution and interaction between tunnels. Instrumentation and mapping were used to verify assumptions during construction. Convergence data is compared to design estimates. Lastly, recommendations for successful design and construction of similar tunnel intersections in rock are made.
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