滇中引水工程白云岩砂化隧洞涌水突泥处理研究

Treatment of mud and water inrush in sanded-dolomite tunnel of Central Yunnan Water Diversion Project

为了解滇中白云岩砂化特征,剖析其形成机理,探索滇中白云岩砂化隧洞涌水突泥的处置方法和措施,以滇中引水工程松林隧洞为例,对上述3个方面进行系统研究。研究结果表明:①滇中白云岩砂化为白云岩中可溶的方解石溶蚀流失后,不溶物石英砂颗粒填充溶蚀通道形成的砂化现象。由于进入白云岩砂化洞段前围岩条件好,导致涌水突泥具有突发性。②白云岩砂化段因结构松散易发生垮塌,在地下水的持续冲蚀下,断层带内松散的岩块发生软化和进一步垮塌形成空腔,产生集中涌水通道,形成反复涌水突泥。③白云岩砂化洞段涌水突泥处理措施包括快速抽排清淤、反压及封闭掌子面、布置超前排水孔降低空腔水压、对渣体进行灌浆形成支撑体、采用超前大管棚和小导管灌浆、利用超前探孔找出空腔位置并采用混凝土回填等方面。④超前地质预报是预防白云岩砂化洞段涌水突泥的基础,初期塌方快速封闭和反压处理是预防涌水突泥的关键。

Examining sandification characteristics of dolomite in central Yunnan Province,analyzing its formation mechanism and discussing the disposal measures for mud and water inrush in sanded-dolomite tunnel is meaningful for construction of Songlin tunnel in Central Yunnan Water Diversion Project.Results show that the sandification is formed because insoluble quartz sand particles fill the dissolution channels that are formed by loss of soluble calcite in dolomite.If the lithology in front of the sanded-dolomite is relatively good,when excavating in this sanded-dolomite section the water inrush would be sudden.Due to the loose structure in the sanded-dolomite section,rock mass collapses occur frequently under successive water erosion,which forms new water flowing channel and it further enlarges the water inrush quantity and frequency.The treatment measures of mud and water inrush in sanded-dolomite tunnel include quick draining and removing silt,exerting reverse pressure and sealing the tunnel face,arranging advance drainage holes to reduce the water pressure of cavity,grouting the slag body to form support body,using advance large roof-pipe and small pipe grouting,using advance probing holes to find out the position of cavity and using concrete backfill,etc.It is concluded that the basis for preventing mud and water gushing in the sanded-dolomite tunnel is implementing geological prediction in advance strictly,and the rapid closure for early collapse and exerting reverse pressure treatment are key measures.