西宁市城东区湟水河附近区域基坑施工难点分析及应对措施

针对西宁市城东区湟水河附近区域由于地下水水位较高,且卵石层中含有大漂石,卵石层以下泥岩层中裂隙较多,裂隙中充填的石膏及芒硝有水流动时容易出现溶蚀现象的工程地质及水文地质特征,结合多个工程实例.详细分析了在基坑工程施工时采用常规的桩锚支护结构、土钉墙支护结构,管井降水以及高压旋喷桩止水帷幕等基坑支护形式和基坑止水排水措施...

Difficulties Analysis and Countermeasures of Foundation Pit Construction near Huangshui River in Chengdong District of Xining City

In view of the engineering geological and hydrogeological characteristics of the area near Huangshui River in Chengdong District of Xining City,due to the high groundwater level,the pebble layer contains large boulders,there are many cracks in the mudstone layer below pebble layer,the gypsum and mirabilite filled in the cracks are prone to dissolution when water flows,combined with several engineering examples.This paper analyzes in detail the problems that often occur in the construction of foundation pit engineering,such as the conventional pile anchor support structure,soil nailing wall support structure,pipe well dewatering and high-pressure jet grouting pile water stop curtain,as well as the water stop and drainage measures of foundation pit,such as the pebble layer is easy to collapse and the pile is difficult to form;when the high-pressure jet grouting pile encounters large boulders,the jet grouting effect is affected;after the jet grouting pile enters the mudstone layer,the cutting radius is greatly reduced and the water stop curtain can not be formed;due to the poor water stop effect,the open drainage of the foundation pit must be combined with the open drainage of the foundation pit during the excavation of the foundation pit,long-term pumping leads to the loss of fine particles in the pebble layer.At the same time,the dissolution of gypsum and Mirabilite in the mudstone layer leads to the increase of cracks between mudstone layers,resulting in the ground settlement around the foundation pit and the uneven settlement of surrounding buildings,resulting in settlement cracks in the superstructure.Through engineering practice,the combination of bite pile+non-shrinkage double slurry grouting(WSS grouting)is finally selected for foundation pit support and water stop,which successfully solves the problems encountered in the construction of conventional foundation pit support structure and water stop structure,and provides a good reference for the construction of foundation pit engineering and underground structure in similar engineering geological sites.