桩锚与土钉联合支护结构中的土压力分配模式

桩锚与土钉联合支护结构中,土压力在桩锚和土钉之间的分配是联合支护结构设计的关键所在.土钉对土体的加强将使直接作用于桩锚结构上的土压力得到显著减小,从而降低桩锚结构中的锚杆应力水平,减短排桩插入土中深度.通常情况下桩锚与土钉联合支护结构的基坑边壁侧移很小,土钉长度范围内一般不会出现显著的破裂面,此时土钉支护部分可视为土压力向桩锚结构传递过程中的中间单元.据此可计算桩锚与土钉联合支护结构中土压力在二种支护结构间的分配及联合支护结构的协调变形问题.通过工程实例基坑边壁侧移的计算和监测结果对比,验证了土压力分配模式的工程适用性,对同类支护结构的设计计算具有一定的参考价值.

The Admeasurement Model of Earth Pressure in the Combined Structure of Pile-anchor and Soil Nailing

It is the key problem for the combined retaining structure to distribute the soil pressure to the pile-anchor and the soil nailing reasonably. For soil nailing, the soil of the retained section is strengthened by soil nails. If pile-anchor and soil nailing(PASN) are combined together, the prestress level will be reduced and the embedded depth of soldier pile be shortened, for the earth pressure acting on the pile-anchor retaining structure is observably lessened due to the strengthening action of soil nails to the soil. Generally, the side displacements of combined structure of PASN are very small and failure surface will not occur within the length of soil nails. So the section of soil nailing can be treated as a middle element during the earth pressure transferring to pile-anchor retaining structure, based on which we can admeasure the earth pressure in the combined structure of PASN and analyze the harmonious deformation between them.By comparing the calculation result of the side displacement and the observed result of the foundation pit side wall of an constructed project, the applicability of the soil pressure distribution model is verified,and this can provide some reference for the designing and calculating of the congener retaining structure.