【作者】 杜西岗；

【导师】 吴雄志；

【作者基本信息】 河北工程大学 ， 岩土工程， 2010， 硕士

【摘要】 土钉支护是以土钉作为主要受力构件的边坡支护技术,它由密集的土钉群、被加固的原位土体、混凝土面层和必要的防水系统组成。同时为了增加其稳定性能,在支护结构中常设置减压平台。它通过提高土体的抗剪强度及土体在变形时土钉提供给土体的抗拔力达到支护目的,是一种主动受力的支护结构。由于它具有施工快速便捷、适用性强、经济可靠等优点,而广泛应用于各种工程的土体支护项目中。但在理论上对土钉支护的工作机理和稳定性研究这一问题仍没有得出透彻的认识,导致设计人员在进行土钉支护设计时所考虑因素的重要性不是很合理,设计结果与真实情况存在很大差距。本文通过准粘聚理论,在众多学者对土钉支护结构研究的基础上,提出了减压平台这一概念,对土钉支护抗剪强度的提高机理进行了分析研究,并推导出破裂角的表达式。对于设置减压平台的土钉支护结构,通过剪滞法理论推导了减压平台所在平面之上、之下的土钉内力传递公式,并与未设置减压平台的情况下进行内力比较。在分析了前人破坏模型的基础上,结合实际工程的检测资料及实地经验,从理论上提出了支护结构的拉裂—滑移双直线潜在多破裂面的破坏模型,并推导其稳定性计算公式。最后,通过对一个土钉支护工程实例的坡体水平位移和土钉拉力进行检测,得出设置减压平台的土钉支护工程中坡体水平位移和土钉拉力随施工时间、挖土深度的变化情况。将土钉拉力的实测结果与由土钉内力传递公式计算所得结果相比,两者基本吻合,土钉最大拉力作用点也在理论分析的潜在破裂面附近,这验证前述理论分析的正确性,对土钉支护的设计和施工提供很好的参考价值。更多还原

【Abstract】 Soil nailing is a supporting technology with a soil nailing as the main force component of the slope. It consists of dense group of soil nailing, in–situ soil reinforced, concrete surface layer and the necessary water system.Meanwhile, in order to increase its performance of stability, decompression platform is frequently set in the supporting structure. It is a supporting structure of active force and by increasing the shear strength of soil to achieve the purpose of supporting. It is widely used in various projects of soil supporting for the advantages of fast and easy construction and economic reliability. However, in theory, the mechanism and stability of soil nailing has yet to arrive at a thorough analysis. It leads to the designer taking into account unreasonable importance of the factors during the design of soil nailing, and the design results is very different with the real situation.In this paper, using quasi-cohesion theory, on the basis of many previous studies of soil nailing structure, a new concept of decompression platform is put forward and on the shear strength of soil nailing an analysis in the improvement of the mechanism is studied. To the soil nailing structures that set decompression platform, the internal forces transmission of soil nailing where is up and below the platform is derived from the shear-lag method, and compared with the condition in which structure does not set platform. After analyzing the damage models based on the predecessors, combined with the monitoring data of actual project and field experience, a theory of crack-sliding and a potential multi-sliding pairs of linear damage model is put forward and its stability formula is derived. Finally, through monitoring horizontal displacement and soil nailing force of a structure, a result to the soil nailing structures which set platform that the horizontal displacement and soil nailing force change with the construction time and digging in depth is derived. Comparing the experimental result of soil nailing force, the result of the internal forces from the soil nailing formula is similar, and the point of the largest soil nailing forces is also near the potential fracture plane of the theoretical analysis. The results of this study provide a good reference value to the design and construction of soil nailing structure.更多还原