杭州地铁1号线穿越钱塘江地层沼气释放技术探讨

Technology for Methane Releasing in Shield Tunneling Through Qiantang River Formation: Case Study on Line 1 of Hangzhou Metro

杭州地铁1号线穿越的钱塘江地层中含有大量沼气,隧道在盾构推进过程中存在很大的工程风险。地层中沼气的赋存多为囊状形式存在,主要位于淤泥质粉质黏土与粉砂交界处。为了尽可能地将地层中的沼气释放出来,通过对试验段沼气进行释放施工,了解沼气的赋存特点并采取相应的释放技术,结合盾构隧道施工的工程特点,指导过江隧道段沼气释放安全施工,以达到降低盾构推进线路附近地层中沼气含量的效果。从盾构推进过程中未发现有沼气突出的情况看,释放效果比较好。

Line 1 of Hangzhou Metro passes through Qiantang River formation, which contains large amount of methane. Therefore, there is great risk in shield tunneling. The methane is mainly located at the junction between the silty clay and silty sand. Methane releasing trials are made so as to understand the occurrence characteristics of the methane and, in turn, to make preparations to take countermeasures. During the shield tunneling, no methane outburst occurs, which demonstrates that the methane releasing is effective.