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钢拱架支撑是地下洞室开挖中的重要支护型式之一,与喷锚支护措施相结合能够有效地控制围岩变形和减小围岩失稳机率.结合某水电站工程实际,针对不支护、喷锚支护、钢拱架与喷锚联合支护等不同情况,采用三维有限元法对导流洞开挖过程中围岩的位移、塑性区,喷层、锚杆及钢拱架的应力分布情况进行了计算分析.结果表明:与普通的喷锚支护相比,采用钢拱架与喷层、锚杆组成联合支护体系能够对围岩变形提供直接抗力,围岩位移和塑性区范围大大减小,各支护材料的应力也有较大程度的降低,为导流洞围岩破碎洞段施工期的稳定提供了有力的保证.
Steel arch support is one of the important support patterns in excavation of underground caverns, which can effectively control the deformation of surrounding rock and reduce the probability of surrounding rock instability in combination with spray anchor support measures.According to the engineering practice of some hydropower station, No support, spray anchor support, steel arch and spray anchor joint support and other different situations, using three-dimensional finite element method for diversion tunnel excavation process of surrounding rock displacement, plastic zone, spray layer, anchor and steel arch The results show that compared with normal shotcrete and rock bolting support, the combined support system of steel arch and shotcrete and rock bolt can provide direct resistance to surrounding rock deformation, displacement of surrounding rock and Plastic zone greatly reduced the scope of the various supporting materials also have a greater degree of stress reduction for the diversion tunnel rock broken section construction period provides a powerful guarantee.