Organised by
Tunnelling & Underground Space Technical Division, IEM


SYNOPSIS

As part of Rancangan Tebatan Banjir Sg. Bunus, Wilayah Persekutuan Kuala Lumpur, the Department of Irrigation and Drainage (DID), Wilayah Persekutuan has implemented a project to mitigate flooding issues in the Sg. Bunus catchment area. The main objectives of the project are to protect lives; safeguard the health and safety of residents in the community; reduce damages to structures due to flooding; and to ensure a sustainable future for the community. Both soft-engineered features and structural measures have been considered in the project, which include storage ponds, in-stream storage, planting of vegetations, tunneling, underground storage tanks and pumping stations.

A twin box culvert would act as a vital connection between Sg. Bunus and Sg. Klang acting as a control-gate structure that hoist force main drainage pumping system that lifts low water level from Sg. Bunus to high water level of Sg Klang.

In order to construct a cast-in-situ twin box RC tunnel (serving later as a pump gate drainage culvert) within the existing Reinforced Earth (RE) wall road ramp, a temporary pipe-roofing system (Microtunelling) is introduced.

The first of its kind in the world pipe-roofing tunneling system through RE wall road ramp has been designed for the above purpose. The system encompasses the insertion of a series of horizontal contiguous steel pipes (600mm dia.) at shallow depth beneath and through the existing highway RE wall road ramp by hydraulic steel pipe jacking, including jacking in the vertical directions.

Stability Enhancement Measures  

1. Prior to the advancing steel pipes, a Cement-Bentonite mixture slurry would be grouted into the RE wall granular material of the ramp to solidify it as well as  to control the loss of the granular material during the pipe jacking operation.  

2. Permeation grout is injected below the RE wall strip foundation to enhance its bearing capacity.

3. Steel tie-rods are introduced in a triangular pattern which are inserted and tightened horizontally to ensemble and sandwich both faces of the RE wall panels to enhance the ramp stability against the pipe jacking forces, and both the RE wall panel faces are then covered with reinforced concrete gunite.  

4. The abovementioned technique provides measures to control ground movements during pipe jacking. This is so that the settlements of both overlying and road pavement as well as the movement of RE wall panels are minimised and maintained within the acceptable limits, otherwise this would cause disturbance to the live traffic. And for that purpose, two types of monitoring systems are implemented, i.e. Automatic Total Station (ATS) & Terrestrial Laser Scanning (TLS) which have been counterchecked by precise manual levelling monitoring survey.

SAFETY REMINDER:
Participants shall be well-equipped with their own PPE equipment, i.e. safety helmet, safety vest and safety boots in order to be allowed access into the site.

NOTE:
• The visit is strictly limited to 30 participants registered on a first-come, first-served basis