高应力条件下巨型地下洞室穹顶施工方案比较

发布时间：2018-04-04 02:27

本文选题：水利工程　切入点：地下洞室　出处：《科技通报》2017年01期

【摘要】：白鹤滩水电站地下洞室群规模宏大且围岩地质条件复杂,尾水调压室洞径达48 m,大型穹顶面临着局部高应力条件下应力集中区的脆性岩体破裂问题和两翼松弛区的变形稳定问题,而不同的开挖方式将明显影响开挖过程的应力损伤和松弛变形控制效果。采用FLAC3D建立了白鹤滩右岸尾水调压室"槽形开挖"和"环形开挖"方案的数值模型,基于白鹤滩岩石力学特性定义了脆性玄武岩启裂强度的标准,并且采用三维空间等值面技术比较了开挖应力集中程度和范围,从而对开挖应力损伤、松弛变形、塑性区分布等特征进行了比较说明。研究表明,槽形开挖有利于控制应力集中和提供有效支护时机,可作为优选方案。此外,在局部应力型破坏风险更高的部位,建议采用平行于最大主应力方向的槽形开挖,从而更有效地控制顶拱中部应力集中和侧翼松弛变形。研究工作采用数值分析进行大跨度穹顶施工方案比较,可以为类似中等至深埋地下工程施工方案比选与优化提供参考。
[Abstract]:The underground cavern group of Baihetan Hydropower Station is large in scale and complex in surrounding rock geological conditions.The diameter of tailrace surge chamber is up to 48 m.The large dome is faced with the problem of brittle rock mass rupture in the stress concentration region and the deformation stability problem in the flabby region under the condition of local high stress.The stress damage and relaxation deformation control effect of excavation process will be obviously affected by different excavation methods.The numerical models of "trench excavation" and "ring excavation" for the tailings surge chamber on the right bank of Baihetan are established by using FLAC3D. Based on the rock mechanical properties of Baihetan, the criterion of crack initiation strength of brittle basalt is defined.The degree and scope of stress concentration in excavation are compared by using three-dimensional space isosurface technique, and the characteristics of excavation stress damage, relaxation deformation and plastic distinguishing cloth are compared and explained.The results show that the trench excavation is beneficial to control stress concentration and provide an effective supporting opportunity, and can be used as an optimal selection scheme.In addition, it is suggested that trench excavation parallel to the direction of maximum principal stress should be used to control stress concentration and flank relaxation in the central part of the arch.The numerical analysis is used to compare the construction schemes of large span dome, which can provide a reference for the comparison and optimization of the construction schemes of similar medium to deep buried underground projects.
【作者单位】：浙江中科依泰斯卡岩石工程研发有限公司;中国电建集团华东勘测设计研究院有限公司;
【分类号】：TV554

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