埋藏式钢岔管与外围结构的联合作用分析

为了更深入地了解埋藏式岔管与外围结构联合承载的力学机理,采用三维有限元法对岔管与外围结构联合作用做了精细的力学仿真。尝试了一种新的模型,即设置回填混凝土网格,模拟钢岔管、混凝土、围岩三者之间的两道缝隙及其力学接触行为,考虑混凝土承载后的塑性变形特征。结果表明,岔管与外围结构在空间中的相互作用过程复杂:由于岔管与外围结构联合承载,使钢材强度得到了充分的发挥;回填混凝土未沿径向均匀开裂,基于此假定的力学模型值得商榷;回填混凝土变形应被充分重视,有些部位的压缩变形甚至大于结构间原始缝宽,不利于联合承载;两道缝模式得出的内水压力围岩分担率明显低于一道缝模式,后者可能高估了围岩分担率。研究成果为埋藏式岔管受力分析提供了一种新模式。

Analysis on combined action of embedded steel bifurcated penstock and its surrounding structure

In order to understand the mechanical mechanism of the combined-bearing of the embedded steel bifurcated penstock and its surrounding structure， an elaborate mechanical simulation is made on the combined action with 3-D finite element method, for which a new kind of model is tried， i.e. setting backfill concrete mesh， simulating two gaps in between steel bifurcated penstock， concrete and surrounding rock and their mechanical contact behaviors and considering the plastic deformation characters after the bearing of concrete. The study shows that the process of the interaction between the bifurcated penstock and its surrounding structure is spatially complicated. Due to the combined bearing of both the bifurcated penstock and its surrounding structure， the strength of the steel is fully exerted， while the backfill concrete does not uniformly crack along the radial direction， thus this assumption-based model is necessary to be further deliberated. Moreover， full attention must be paid on the deformation of the backfill concrete， for which the compressive deformations at some locations are even larger than the initial widths of the gaps in between the structures， and then unfavorable to the combine bearing. The sharing rate of the surrounding rock for the internal water pressure obtained from the mode with two gaps is obviously lower than that from the mode of one gap， thus the sharing rate of the surrounding rock is possibly overestimated by the latter. A new mode for the stress analysis on the embedded bifurcated penstock is given herein.