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研究圆巷“开挖-支护”过程中掘进头附近承载结构形成机理和发展规律。基于Drucker-Prager屈服准则和Levy-Mises本构关系,考虑开挖损伤因素,获得围岩次生应力场、位移场的解析式,由蠕变效应推导承载结构演化方程组。依据切向应力“增-减-集中-趋稳”划分次生承载结构为“主动-被动-关键-自稳”承载圈,由算例可知,随着岩性增强和支护力增大以及掘巷速度、损伤程度、锚杆间排距和地压的减小,“主动-关键”圈更靠近巷壁,其中“关键”圈厚度和应力集中系数增大,使得围岩初始支护难度减小、承载能力增强。各承载圈厚度及与巷壁间距离随着蠕变效应发生变化,当地压在20 MPa时,采用锚杆支护力为0.4 MPa、间排距600 mm×600 mm,及时地封孔注浆减小软化系数,有助于提高围岩承载能力,加快进入蠕变稳定期,并有效地控制住“关键”圈转移,抑制其厚度增大,降低巷道后期维护难度。
Research on the formation mechanism and development rule of bearing structure near excavation head during rounding, excavation and support. Based on the Drucker-Prager yield criterion and the Levy-Mises constitutive relationship, the analytical solutions of the secondary stress field and displacement field of the surrounding rock were obtained considering the damage factors of excavation, and the evolution equations of the bearing structure were deduced from the creep effect. Based on the tangential stress, “increase-decrease-concentrate-stabilize”, the secondary bearing structure is divided into “active-passive-critical-steady” bearing ring. The increase of force and the decrease of the speed, damage degree, spacing between bolts and ground pressure, the “active-critical” ring is closer to the laneway wall, and the thickness of the “key” ring and the stress concentration factor increase , Making the initial support of surrounding rock reduced difficulty, carrying capacity increased. The thickness of the bearing rings and the distance between them changed with the creep effect. When the local pressure was 20 MPa, the supporting force of the bolt was 0.4 MPa and the spacing between the bolts was 600 mm × 600 mm. Reduce the softening coefficient, help to improve the carrying capacity of surrounding rock, accelerate the creep stability period, and effectively control the “key ” circle transfer, inhibit the increase of its thickness and reduce the difficulty of roadway maintenance.