ABSTRACT
Protective work such as underpinning and ground improvement are routinely used to reduce tunnelling induced impacts, ensuring safety and serviceability of vulnerable existing building structures. This paper presents two case studies where the construction of the new Klang Valley Mass Rapid Transit- Line 2 in Kuala Lumpur, Malaysia, crosses very closely below the existing structures. The first case involves the underpinning of a 5-storey building located above the proposed tunnel alignment with some of its piles located within the tunnel horizon. Pile removal was designed to be carried out while the building was occupied. In the second case study, the same tunnel crosses beneath an existing reinforced concrete retention pond of a pumping station where partial pile removal was required to allow unobstructed access for the TBM. Despite the improved ground support from jet grouting, additional analyses were required as the underpinning work changes the response of the reinforced concrete structure.
