Land Transport Authority – Downtown Line 3, Singapore

Ground conditions of the EPB TBM tunnel drive were in Old Alluvium (OA) and mainly made up of very stiff clay. The advance rate of the TBM was slow at 7 - 8 mm/min and the TBM was experiencing very high torque.

The ideal target advance rate was to achieve 20 mm/min in order to meet the tight project completion schedule to avoid a heft daily LD. The advance rate had to be increased by at least two times to meet the deadline.

For years, Minera Tayahua applied sprayed concrete manually. However, there were imperfections in the spraying process, hindering the efficiency of the operation. The sprayers had insufficient knowledge of the spraying process, which resulted in high consumption of cement and accelerator. And on site, it was also observed that the quality of the concrete was inconsistent.

Although the company was operating four Alpha 20s, the equipment’s performance was not up to par due to a lack of proper maintenance.

Normet understood the challenges faced and came up with a solution, but at that time the company did not have the suitable product. Global resources were gathered and within a week’s time, we managed to bring in the raw material from Europe and developed the new TamSoil product locally at Normet’s factory.

The product developed was the TamSoil 280AC, a clay dispersant foaming additive for EPB TBM tunneling. TamSoil 280AC was delivered to site for use on the TBM in a week from the first meeting with the contractor. An instant improvement in advance rates was observed.