采用三维有限元模拟了岔管、回填混凝土与围岩的联合承载体,分析了回填混凝土的塑性性质、岔管与回填混凝土之间的缝隙及围岩力学性能等重要因素对联合承载体的影响。结果表明:考虑回填混凝土的塑性性质后,围岩分担率下降;缝隙宽度超过一定值后,回填混凝土与围岩对岔管约束急剧下降,围岩分担率接近0;围岩力学性能越好,围岩分担率越高;考虑联合承载后,水压试验时岔管可能不足以承担1.25倍的设计压力,应根据岔管钢材允许应力研究水压试验值。研究成果为钢岔管与围岩共同分担内水压力的埋藏式月牙肋岔管的设计提供了参考。

The combined bearing structure of crescent-rib bifurcated pipe, backfill concrete and surrounding rock is simulated using 3D finite element method. The important roles including the plastic characteristics of backfill concrete, the gap between crescent-rib bifurcated pipe and backfill concrete, and the mechanical properties of surrounding rock are analyzed. Results showed that the sharing ratio of surrounding rock decreased with the plastic properties of backfill concrete into consideration; when the gap width exceeded a certain value, the constraint of backfill concrete and surrounding rock to crescent-rib bifurcated pipe plummeted, and the sharing ratio of surrounding rock was close to zero; the better the mechanical properties of surrounding rock, the higher the sharing ratio of surrounding rock. In the presence of combined bearing, the crescent-rib bifurcated pipe may not be able to bear 1.25 times of the design pressure in hydraulic test. Therefore, the allowable stress of crescent-rib bifurcated pipe must be considered in hydrostatic test. The research findings provide reference for design of embeded crescent-rib bifurcated pipe with surrounding rock sharing the internal pressure.