不良地质条件下预应力锚杆岩壁吊车梁设计研究

Design and research of prestressed rock bolt crane girder under adverse geological conditions

摘要

对于不良地质条件下的地下厂房岩壁吊车梁设计，国家能源局规范NB/T 35079—2016未做较为明确规定。由于不良地质条件下围岩释放应力难以准确预估，普通砂浆受拉锚杆受力离散型较大，难以完全保证岩梁安全稳定运行。提出并验证了可重新张拉的预应力锚杆岩壁吊车梁设计方案，该方案预应力锚杆深入稳定围岩，受围岩释放应力影响较小，在施工和使用过程中，若预应力锚杆受力超标，可对预应力锚杆松弛再张拉，保证长久安全稳定运行。数值计算结果表明，预应力锚杆岩梁可与围岩紧密贴合，较普通砂浆锚杆岩梁具有更可靠的整体稳定性，有利于减小围岩和结构间的开合度，保障结构与围岩的黏聚力和摩擦力的有效发挥，提高岩梁整体稳定性。最后，以以色列Kokhav Hayarden抽蓄地下厂房的预应力锚杆岩梁作为案例，验证了预应力锚杆岩梁具备较大的安全裕度，设计合理可行。

Abstract

The code NB/T 35079—2016 does not provide clear guidance on the design of crane girders for underground power plants under adverse geological conditions. Due to the difficulty in accurately estimating the release of rock mass stress under adverse geological conditions, the non-prestressed rock dowels have a large scatter in their tensile force, which makes it difficult to fully guarantee the safe and stable operation of the crane girder. A design scheme of re-tensionable prestressed rock bolt crane girder was proposed. The prestressed rock bolt penetrates into the stable rock mass, and is less affected by the release of rock mass stress. During construction and operation, if the prestressed rock bolt is overloaded, it can be relaxed and re-tensioned to ensure long-term safe and stable operation. Numerical calculations show that the prestressed rock bolt crane girder can closely contact the rock mass, with more reliable overall stability compared to the non-presstressed rock dowel crane girder, which is beneficial for reducing the gap between the rock mass and the structure, and ensure the effective exertion of cohesion and friction between the structure and the rock mass, thus improving the overall stability of the crane girder. Finally, the prestressed rock bolt crane girder of the Kokhav Hayarden pumped storage underground power plant in Israel is used as a case study, which verifies that the prestressed rock bolt crane girder has a large safety margin and the design is reasonable and feasible.

关键词

不良地质条件 / 释放应力 / 重新张拉 / 预应力锚杆 / 岩壁吊车梁 / 附壁墙

Key words

adverse geological conditions / stress release / re-tensioning / prestressed rock bolt / crane girder / attached prestressed concrete wall