深基坑桩锚与土钉联合支护的三维有限元模拟

桩锚土钉联合支护在工程中应用广泛,以郑州某基坑桩锚土钉联合支护工程为实例,分别建立单独土钉支护、单独桩锚支护、桩锚土钉联合支护模型,采用有限元(Midas GTS NX)软件对3种模型进行数值模拟。通过对数值模拟结果的综合对比分析,得出以下结论:单独土钉支护的基坑土体最大水平位移量、坑底最大隆起量以及土钉最大轴力较桩锚土钉联合支护均偏小,因此单独土钉支护的设计思路偏不安全;单独桩锚支护的支护桩最大水平位移量、桩身最大弯矩以及锚杆最大轴力较桩锚土钉联合支护均偏大,因此单独桩锚支护的设计存在局限性;桩锚土钉联合支护桩身水平位移随桩长变化规律及桩身弯矩变化规律较单独桩锚支护有所不同,依据2种支护方式间的协同作用,因此桩锚土钉联合支护的设计思路更为合理。

Three-dimensional finite element simulation of combined supporting of pile anchor and soil nail in deep foundation pit

Pile anchor and soil nailing wall composite supporting structure were widely used in engineering.Taking a foundation pile anchor and soil nailing wall composite supporting structure in Zhengzhou as an example,this paper established three different numerical simulation models for the upper soil nailing wall,the pile-anchor structure under the upper soil nailing wall and the whole composite supporting structure.Midas GTS NX was used to simulate the models.Through comprehensive comparative analysis of the numerical simulation results,the following conclusions were drawn:the maximum horizontal displacement,maximum heave of pit bottom and maximum axial force of the upper soil nailing wall were smaller than the whole composite supporting structure,so the design idea of the upper soil nailing wall was not safe.For pile-anchor structure under the upper soil nailing wall,it′s maximum horizontal displacement,maximum bending moment of pile body and maximum axial force of bolt were larger than the whole composite supporting structure,so the design idea of pile-anchor structure under the upper soil nailing wall was conservative.The change law of horizontal displacement and bending moment of the whole composite supporting structure were different from pile-anchor structure under the upper soil nailing wall.Considering synergy between two supporting modes,the design idea of the whole composite supporting structure was more reasonable.