A Case Study of Ground Settlement and Volume Loss from Pipe Jacking and Microtunelling Activities for Sewerage Pipe Installation in Ipoh, Perak.

Abstract

A case study of sewerage pipeline installation utilizing pipe jacking and MTBM in Ipoh, Perak, Malaysia was conducted to analyse the ground response by quantifying the soil volume loss and ground surface settlement. The sewerage pipeline installation involves tunnelling and jacking beneath the KTMB railway track for 191m from jacking to receiving pit.The excessive horizontal and vertical deviation of MTBM when excavating through very loose sand and soft clay leads to an uncontrolled overcut and affecting the magnitude of the ground surface settlement where 100mm and 130mm for horizontal and vertical deviation respectively produce 49mm of ground surface settlement. The maximum settlement for the railway track was 12mm over 30m chords length (0.0004) after two months of project completion still within the allowable limit set by KTMB (11mm over 10m chords for intervention (0.001). The volume loss calculated from this project ranging from 0.80% to 12.68% contributes by the lowest and the highest ground surface settlement which is - 3mm and - 51 mm, respectively which varied from the 8mm estimated ground surface settlement by assuming 2% of volume loss. It was found that the trough width parameter K = 0.5 matches the settlement trough of collected field data. In conclusion, soil volume loss and ground surface settlement was affected by the MTBM deviation.