大跨矿山法隧道长距离下穿高压燃气管技术

(中铁第一勘察设计院集团有限公司,陕西 西安 710043)

土木工程; 燃气; 大管棚; 减振孔; 爆破; 矿山法

Technology for large-span mine tunnel long-distance crossing underneath high-pressure gas pipeline
LI Hai-long

(China Railway First Survey and Design Institute Group Ltd.,Xi'an 710043,China)

civil engineering; gas; large pipe shed; damping hole; blasting; mine method

DOI: 10.13800/j.cnki.xakjdxxb.2019.0423

备注

地铁隧道穿越重大地下管线已成为地铁工程中重要的技术问题,依托于青岛地铁8号线河套停车场出入线区间长距离穿越DN630高压燃气管的案例,由于场线隧道断面大、埋深浅,所处地层节理裂隙密集发育、稳定性差,普通施工方法必然会造成较大的燃气管沉降; 同时高压燃气管对爆破振动较为敏感,如何控制爆破振速是设计难点。文中通过数值模拟与现场实测相结合的方法,借助大型岩土有限元分析软件Midas NX,对大跨隧道穿越燃气管进行数值模拟; 同时对现有燃气管线进行监测,获得沉降及爆破振速变化曲线。经综合分析与对比后,结果表明:管线沉降限值8 mm及爆破振速限值0.5 cm/s可保证高压燃气管的安全; 采用无工作室大管棚技术并辅助其他工法优化措施可有效地控制管线沉降; 采用减振孔减振技术,同时洞内尝试大直径中空孔直眼掏槽、导洞法、周边眼加密等措施可有效地控制爆破振速。研究成果对指导类似矿山法隧道穿越重大管线及重要建构筑物的设计和施工具有重要的参考价值。

The exit line of the Hetao vehicle base of Qingdao Metro Line 8 needs to be long-distance crossing a DN630 high-pressure gas pipe.Due to the large section and the shallow depth of the field line tunnel, the joint cracks in the stratum are densely developed and the stability is poor. The ordinary construction method does not work, which will cause a large gas pipe to settle; and the high pressure gas pipe is sensitive to blasting vibration, so how to control the blasting vibration velocity is a difficulty in design.In this paper, through the combination of numerical simulation and on-site measurements, the large-scale geotechnical finite element analysis software Midas NX is used to simulate the settlement and blasting vibration caused by the large-span tunnel crossing the gas pipeline.At the same time, the existing gas pipeline is monitored, with settling and blasting vibration velocity curves obtained.An comparison of the results shows that the pipeline settlement limit of 8mm and the blasting vibration velocity limit of 0.5cm/s can ensure the safety of the high-pressure gas pipe; it is effective to use the non-studio large pipe shed technology and adopt other engineering optimization measure as well to control pipeline settlement.The vibration-reduction technology of the vibration reduction holes can be used to control the blasting vibration speed assisted by such measures as straight-eye grooving in large-diameter hollow hole,guiding hole method and peripheral eye encryption.The research results provide a guideline for the design and the construction of major pipelines and important structures in similar mine tunnels.