*Zeid Thabet Youssef , ** Ali A.S. Taleb

* Faculty of Engineering Emirates University of Aden, Aden-Yemen

** Hyder Consulting , Abu Dhabi, United Arab


Microtunnelling in soft soil may lead to ground surface settlement causing damage to structures,

existing roads, services and utilities. The present case study investigates the effectiveness of

preventive measures adopted to minimize ground surface settlement to within the permissible limits by

road authority of Abu Dhabi Municipality. The preventive measures undertaken include the use of

appropriate microtunnelling machine equipped with slurry system, continuous lubrication to the drive

during the microtunnelling to minimize the jacking force and the over cutting space between pipes and

soil media, immediate sealing to the gab between the pipe and soil after completing each drive,

maintaining continuous round the o’clock drive and minimizing the break time required to the

installation of subsequent pipes. For this purpose three microtunnelling drives of different lengths and

at different levels crossing beneath the existing roads were selected. Road surface movements above

each drive were monitored before, during and after completion of the tunneling works. The difference

in the levels was calculated, presented in graphical forms and discussed. The recorded values were

also compared with the calculated maximum anticipated settlement available in the literature. The

results have shown that the recorded road surface settlement for all drives falls within the allowable

settlements of 6.0mm.

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