Ⅲ类围岩场地地下水封洞库洞室断面形状比选和合理间距

Comparison of Cross Section Shapes and Selection of Proper Spaces for Underground Water-sealed Rock Caverns in Class Ⅲ Surrounding Rock Ground

采用有限差分程序FLAC3D并基于Ⅲ类围岩场地,对目前地下水封洞库工程中常用的曲墙式和直墙圆拱式两种洞室断面形式作了选型对比分析,并对曲墙式断面的洞室布置合理间距作了试算分析。分析结果表明,在洞室断面面积近似相等的前提下,两种形式的围岩应力分布状态基本接近,曲墙式断面在位移和塑性区的发展范围等方面均优于直墙圆拱式断面;曲墙式断面的两相邻洞室间距在1.25倍洞室跨度时,塑性区由连通而分离。建议主洞室净间距不宜小于1.5倍的洞室跨度。

By us of FED software FLAC3D and based on Ⅲ class surrounding rock ground, the selection within two cavern crosssection shapes-straight wall arch shape and curved wall shape, which are commonly used in underground water sealed caverns project, had been studied and compared. Also, the proper cavern space for curved wall shape was calculated and analyzed. It was shown from the results that with the condition of almost equal sectional areas, the stress distributions in two shapes of surrounding rock are similar; curved wall cross-section is superior to the straight wall arch cross-section in the respects of reducing deformation and plastic zone; for curved wall cross-section shape, the plastic zone within two adjacent caverns will be separated when the space reaches 1.25 times caverns span. Thus it was recommended that the cavern space shall be no less than 1.5 times caverns span.