冻结管对人工冻结构件加筋作用的试验研究及数值模拟

为研究冻结管对人工冻结构件的加筋作用,通过淤泥质粘土人工冻结梁构件三点弯试验,获得了各级载荷下构件的位移值,并运用MARC软件中的加筋单元进行了对应的有限元计算.根据对冻土梁加筋与否,构件特定力学响应的比较分析,揭示了考虑土层冻结构件中冻结管的加筋作用对于增加冻结构件强度,减小变形量及对提高人工冻结支护工程经济效益的重要作用.同时,通过物理试验和数值模拟试验的对比,验证了应用MARC软件进行类似计算的可靠性.

Experimental Study and Numerical Simulation of the Reinforcementof Embedded Freezing Pipes on Artificial Frozen Components

Artificial ground freezing (AGF) brings about high stability, low permeability and economy of artificial frozen components of soil in numerous mining, environmental and foundational projects. Now concerned researchers and engineers have never stopped their steps into the study of applying the AGF on deep pits of soft soil. Meanwhile, it is necessary to point out that the reinforcement of freezing pipes embedded in frozen components has not drawn enough attention, although it will surly increase the economic profits of pit-shoring project. In order to study the reinforcement of embedded freezing pipe on the artificial frozen components, the displacements under different loads were observed through three-point -bend experiment of artificial frozen silt beams. The beam samples were divided into three groups. Group 1 was without any reinforcing articles, Group 2 with embedded freezing pipes and Group 3 with steels. The whole experiment was conducted in the circumstance of -7℃. Corresponding FEM (finite element method) computation was completed applying the MARC software. In the experiment, different failure forms of different groups were performed. A comparative analysis on individual mechanical response caused by whether the component reinforced or not was completed. Based on the experiment on beam components, it is manifested that the freezing pipes increases the strength of frozen components by at least 50% and decreased the displacement by 25% in tendency prediction. The reinforcement in itself will greatly increase economic benefits in artificial freezing shoring projects. That is to say, in practical computation on construction design of pit shoring, whether from the point of view of deformation control or of load control, ignorance of reinforcement of freezing-pipe will increase investment in a project. On the other hand, the comparison between the experimental results and the computed ones has shown a very good agreement both in strength and displacement, which proves the reliability of MARC software in the similar computation.