| 摘要 |
<p>A method of boring a tunnel through a stratum utilizing a shield tunneling apparatus, the process comprising the injection into the stratum at the cutting face of an aqueous material comprising (a) from 0.005-0.05% by weight of a polyethylene oxide of weight-average molecular weight from 2,000,000 to 8,000,000 (b) from 0.05-0.5% by weight of a sulphate-containing anionic surfactant. The method is effective even in difficult soils.</p> |
