复杂环境条件下深基坑分区组合支护设计与应用

On the Design and Application of the Divisional Composite Support to Deep Foundation Pits in a Complex Environment

石家庄市某商业中心深基坑工程周边环境复杂,研究确定了放坡土钉墙支护、桩锚支护和桩锚—内支撑支护相结合的分区组合支护方案,对支护结构的强度、基坑位移等进行了设计计算。基坑监测数据结果表明,该方案合理可行,实施效果良好。当基坑周围环境相差较大时,可采用分区组合支护方案,发挥不同支护方式的优点,在保证基坑支护质量的同时,降低工程造价。桩锚支护结构和土钉支护结构中,锚杆根部和土钉根部附近地表容易出现较大的裂缝,在基坑工程设计、施工时应予重视。基坑水平位移随着离坑角距离的增加而显著增大,对于异形基坑,中部凸出的阳角部位的水平位移增大尤其明显,基坑设计和开挖过程中应加强这些部位的支护。

As the surrounding environment of the deep foundation pit project for a certain commercial center in Shijiazhuang is complex,a divisional composite retaining scheme with soil nailed wall,pile-anchor support and pile-anchor-internal reinforced concrete support is presented for it in the present paper,with the strength of the support structure,the displacement of the foundation pit and the like designed and calculated.The monitored data from the foundation pit show that the scheme is rational and feasible,and the implemented result is successful.When the surrounding environments around the foundation pit are quite different,the divisional composite retaining scheme can be adopted in order to give full play to the advantages of different supporting and retaining methods,so as to reduce the cost of the project uopn the basis of ensuring the quality of the support and retaining for the foundation pit.As far as the pile-anchor supporting structure and the soil nailing supporting structure are concerned,comparatively big cracks may emerge on the ground surface near the ends of the anchoring bolts and soil nails,in which case much attention should be paid when the design and construction of a foundation pit are performed.The horizontal displacement of the foundation pit increases obviously with the increase of the distance from the pit angle.For a special-shaped foundation pit,the horizontal displacement of the bulgy corner in the middle of the pit increases remarkably,owing to which the support of these parts should be strengthened in the course of the design and excavation of the foundation pit.