软土场地不规则深基坑旋喷锚护支撑技术

DISCUSSION ON SUPPORTING TECHNIQUE FOR IRREGULAR DEEP FOUNDATION PIT ON SOFT SOIL GROUND

某工程基坑具有周边环境开阔、开挖范围内土质条件差、基坑平面形状不规则、开挖面积大等特点。对比优选对撑和角撑的结合、环形支撑、锚杆拉撑等支撑形式,大部分区域采用对撑和角撑相结合形式,在沉井位置处加设拉梁板支撑,在对撑和角撑难以布置的区段采用斜向旋喷锚桩作为外拉锚撑,在需严格保护的文物建筑区段,采用布置角撑及拉梁钻孔桩的形式。监测数据表明,基坑水平位移及竖直位移均在设计要求变形控制范围内,且取得了较好经济效益。

A foundation pit project encounters large void environment, poor soil conditions for excavation, irregular plane shape of foundation pit and large excavation area. After comparison among combination between opposite support and angle support, annular support, anchor bar tension support, etc. , the combination between opposite support and angle support is adopted in most area and straining beam slab support is set at well sinking position. Oblique rotary spray anchor pile is set as external tensioning anchor support in area where opposite support and angle support are difficult to be used; angle support and straining beam bored pile are set in areas where cultural and historical buildings need to be strictly protected. The monitoring data indicate that horizontal and vertical displacement of foundation pit are within the deformation control range specified in design and that favorable economic benefits are realized.