淤泥质软土基坑搅拌桩与土钉复合支护结构受力与变形特性

Deformation Characteristics and Mechanical Behavior of Composite Soil Nailing for Mixing Pile in Sludge Soft Soil Foundation Pit

基坑支护对于结构的受力和位移的控制问题一直在设计施工过程中占据重要地位,尤其在软土地质条件下,因为软土自身具有较差的稳定性以及具有流变性等特性。针对淤泥质地质土层基坑的开挖支护结构问题,探讨了搅拌桩复合土钉支护体系在淤泥质地质土层的应用;使用FLAC3D的有限差分程序,结合正交试验方法来探讨影响基坑变形与稳定性的不同因素,同时基于某在淤泥质土地质条件下的基坑施工现场的实际监测结果,深入分析这一支护结构的敏感程度、变形特点与稳定特性,从而来探讨不同干扰因素取值条件下基坑在特定支护情形下的受力特点、变形规律、以及稳定特性。结果表明:搅拌桩和土钉复合支护对基坑以外支护影响较小,且搅拌桩和土钉复合支护轴力呈现两头大,中心小趋势,土钉倾角为30°支护效果最佳。该种支护体系施工工艺简单,并且技术操作相对简单、造价低,具有较高的实践应用价值。

Due to the effects of rheology and sensitivity of soft soil,the control of internal force and displacement of foundation pit supporting structure is particularly important in the condition of sludge soft soil.Aiming at the problem of the foundation pits support in sludge soft soil,application of the composite soil nailing support system of mixing piles in sludge soft soil areas were discussed.The finite difference program of FLAC3D and orthogonal test method were used to explore the different factors that affect the deformation and stability of the foundation pit.Based on the field measurement data of the sludge soft soil foundation pit,the sensitivity,deformation and stability of the foundation pit with mixing pile composite soil nailing were deeply analyzed,so as to explore the specific conditions of the foundation pit under different interference factors.Results show that the composite support of mixing pile and soil nail has little influence on the external support of foundation pit.And the axial force of the composite support of mixing pile and soil nail is larger at both ends and smaller at the center.The soil nailing inclination angle of 30°has the best support effect.The construction technology of this kind of support system is simple,the technical operation is relatively simple,the cost is low,and it has high practical application value.