SmartMeasures AmbergSeismics Tough projects call for smart measures. Titiwangsa mountains, Malaysia Pahang Selangor Raw Water Transfer Project Project Water for 7.2 Million Malaysians Pahang Selangor Raw Water Transfer Project It’s the biggest infrastructure project of Malaysia. Once completed, this Tunnel of 44.6 km length x 5.4 m diam- tunnel will transfer 27.6 cubic meters of raw water per second to a new eter through the granitic Main Range treatment plant. The drinking water will supply about 7.2 million people. Mountains of the Malaysian Peninsular Most of the tunnel is being excavated Malaysia has experienced substantial economic development since the 1980s, using three hard rock TBMs resulting in increasing water demands in the commercial and industrial develop- Contractor: SNUI JV (Shimizu Corpo- ment centres. The Selangor / Kuala Lumpur region, which is the political, commer- ration, Nishimatsu Construction, UEM cial and industrial centre of the nation, is the most important focus for these high Builders Bhd. and IJM Construction), demands which are expected to continue their rapid growth into the 21st century. www.snuijv.com However, the water resources available within the Selangor / Duration Kuala Lumpur region will not TBM tunnelling started in November be able to meet the demands 2010 and will last till end of 2013 (esti- in the near future. mated) A scheme to transfer water from Pahang to Selangor has been proposed to cope with Task this water demand shortfalls. Seismic measurements besides probe Pahang State, which lies to the drilling in all three TBM headings east of Selangor State, possess ample water resources com- pared with their local demand and has sufficient reserve for interstate transfer. Most of the new tunnel is being excavated using three hard rock TBMs. The extent of site investigation carried out along the tunnel alignment from the surface was quite limited given the topography with high overburden, up to 1,200 m. Once into the tunnel drives, serious problems including large breakouts, collapses, flooding and in-rush could arise as a consequence due to little or no warning of adverse «We are geological features. To overcome these drawbacks, the SNUI JV added seismic driving long measurements besides probe drilling in all three TBM headings. tunnels (3 The actual TSP testing on site takes about an hour, and data processing a further TBM drives two to three hours. The SNUI JV is logging continuously machine performance data each exceed- via different sensors on the TBMs. It is desirable that the seismic predictions are ing 11 km in directly related to TBM advance parameters, including penetration rate or TBM length) under thrust forces. Exploring such correlations however, is ambiguous. The success of high ground the SNUI JV’s approach to using all available parameters to support the TBM drives cover of up and mitigate geological risks, can be assessed by comparing the forecast result to 1,200 m in uncertain ground con- of a TSP measurement taken in the TBM-3 drive in February 2012 and the later ditions with only a limited amount of experience of geological conditions actually encountered. These are presented in site investigations carried out from the figure below. the surface. All three TBM drives CI are critical to our construction pro- Type gramme. We have made very good Support 6000 Weathered zone predicted in Granite Weathered zone predicted in Granite experience with the use of TSP to get (m/s) the geological uncertainties better Velocity under control. The TSP forecast is in 4000 40 Parameter good agreement with actual geologi- TSP Forecast 30 20 cal conditions.» (GPa) 10 Bulk modulus modulus Bulk 0 6150 6160 6170 6180 6190 6200 6210 6220 6230 6240 6250 6260 6270 6280 6290 6300 6310 6320 6330 6340 Pittard, Frank 20 Chief Geologist SNUI JV, Malaysia 10 TSP Forecast Longitudinal View -10 Challenges -20 TBM data shows decreasing of 80 Bedrock along the tunnel consists of Boring Energy and increasing ) 2 70 of Penetration Rate 60 metamorphosed rocks of the Karak For- 50 40 30 mation for 3.5 km from the inlet. The boringTBM 20 remaining portion is in hard, abrasive energy (N/mm 10 6150 6160 6170 6180 6190 6200 6210 6220 6230 6240 6250 6260 6270 6280 6290 6300 6310 6320 6330 6340 12 granitic rock. Unforeseen fault zones 10 8 6 partially with water ingress may result in TBM 4 penetration penetration hazard incidents. rate (mm/rev) 2 0 6150 6160 6170 6180 6190 6200 6210 6220 6230 6240 6250 6260 6270 6280 6290 6300 6310 6320 6330 6340 100 80 60 Products Used 40 Rock class Rock grade point 20 Two systems of TSP 203Plus 6140 m 6150 6160 6170 6180 6190 6200 6210 6220 6230 6240 6250 6260 6270 6280 6290 6300 6310 6320 6330 6340 Geological overbreaks due to Medium widely spaced joints, fault gouge, slickenside, very slightly weathered rock Localised spalling of altered closely joints and >5 mm clay Close to medium rock in fault gouge zone widely spaced joints, moderately to highly weathered rock Geological Tunnel Plan Medium widely spaced joints, slightly weathered rock TSP forecast, TBM data and compared geological findings The graphs outline the developing of the TBM power consumption and its pen- etration rate. There is satisfactory correlation between the two parameters and the parameters derived from the seismic exploration data. However, a direct com- parison of seismic exploration data with TBM data is limited by the circumstance that velocity changes are represented as step functions, whereas TBM data show also gradual changes. Gradual changes are almost impossible to image by seismic methods since a defined acoustic impedance contrast is necessary to record seis- mic reflection data. “The prognosis of TSP correlates well with actual geological conditions,” said Nau- fal Bakhudin, geologist with SNUI JV and one of the TSP operators. The first fault gouge zone, found at tunnel heading 6,226 - 6,240 m is indicated by changes in the TBM data as well. It was successfully detected by TSP as a drop in seismic velocity. 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