复杂环境下大断面群洞交叉部位洞桩法施工力学行为及关键技术研究

【作者】 卢佳；

【导师】 王星华； 钟正君；

【作者基本信息】 中南大学 ， 建筑与土木工程， 2009， 硕士

【摘要】 北京地铁10号线工体北路站为分离岛式车站,地处环境复杂,洞室交叉部位多,群洞效应明显。本论文以该工程为研究背景,采用理论分析、数值模拟计算和现场测试等研究方法,对复杂环境下大断面群洞交叉部位洞桩法施工力学行为及关键技术进行了研究。通过研究,得出以下主要结论：1、针对处于复杂环境下的地铁车站,提出二次衬砌顺逆筑相结合的地铁车站整体洞桩法施工技术,研究了洞桩法施工桩、梁、拱之间的相互作用机理,并给出了相应的施工措施,有效降低了地层位移。具体表现为：(1)主洞和联络通道扣拱的先后次序直接影响两者刚度差异,造成两者变形不协调,导致相交处应力集中,尤其是拉应力和剪应力集中程度较高,在施工过程中需要引起重视,因此施工中应尽量缩短主洞和联络通道扣拱的时间差。(2)在联络通道导洞高度变化区域和各导洞几何转折区域,由于刚度的变化,其应力应变值比较高,应力应变的峰值出现在联络通道导洞和主洞导洞交汇区域,特别是转角部位。(3)冠梁、桩、交叉口初支圈梁和折梁施作完毕且在主拱成形之前,冠梁和桩的应力水平较低,但仍然会在交叉口处出现应力集中；附加梁施工完成且在联络通道开口之前,圈梁承受大部分交叉口处各个方向的荷载,但由于其自身几何尺寸相对较大,可将这些荷载传递给冠梁和桩,保证了荷载传递的连续性。(4)由于折梁和初支圈梁同时施工,从结构几何模型上看,类似于拱桥结构,折梁与初支圈梁共同受力,因此折梁施作后各方向应力集中现象均不明显；从各方向的应力分布来看,应力比较大的区域主要分布在折梁水平段和倾斜段的偏中间部位和两段相连的转折部位。2、采用整体洞桩法施工地铁车站,提出了有限导洞空间内、深厚大粒径(h>8m、D>20cm)卵石地层、深桩综合施工技术,初步解决了深厚大粒径卵石地层深桩施工难题。3、提出了大断面群洞交叉部位主辅洞同时采用洞桩法施工的双向扣拱综合技术,施设的附加梁构件初步解决了地下复杂洞室交叉部位的施工难题。更多还原

【Abstract】 Gongtibeilu Station of Beijing Metro Line 10 which have complex environment、multi-chamber cross and multi-cavern effect obviously is separated island platform station. Construction mechanical behavior and key technologies of caven-PBA method applied to cross position of group large section tunnels have been studied in the thesis, with the methods of theoretical analysis、numerical simulation and field test. The main results are as follows:1. For the metro station in complex environment, the whole caven-PBA construction method is proposed, which combines the down straight method and top-down method of secondary lining. The interaction mechanism of piles、beams and arches in caven-PBA method is studied, and the corresponding construction measure which effectively reduce the formation of displacement is given. Specifically as follows:(1) The construction order of main tunnel and the arch buckle of connect tunnel direct influence their stiffness, and cause lack of co-ordination of deformation, stress concentration in the interface, especially tensile stress and a higher degree of shear stress concentration. So in the construction the time difference of main tunnel and the arch buckle of connect tunnel must as short as possible.(2) As the changes in stiffness, the stress-strain values, in the depth changes region of guide tunnel and geometric turning point region of all the guide tunnels the of connect tunnel, is relatively high, and the peak stress-strain appear the intersection of the main tunnel and the connect guide tunnel, especially the corner.(3) The top beams、piles、primary support ring beam of the intersection and the folded beam is constructed before the main arch completed, the stress of the top beam and pile is lower, but stress concentration is still appear in the intersection. The ring beam bear the all directions load before the additional beam completed and the connect tunnel opened, but the geometry is more bigger, the ring beam could delivery the load to the top beams and piles, and ensure the continuity of load transfer.(4) As the folded beam and primary support ring beam construct contemporarily, and from the geometry structural point, the folded beam and primary support ring beam, as arch bridge structure, are co-stressing, and the stress concentration is not obvious after the folded beam constructed. From all direction stress distribution, the regions of the high stress appear in the horizontal section the Partial middle tilt section and the corner of the two section intersection of the folded beam.2. The new integrated construction technology which based on the situation of limited hole space、deep large-size (h>8m、D>20cm) gravel strata and deep-pile is proposed in the metro station constructed by whole caven-PBA construction method, and the technology solve initially the deep-pile construction problem in deep large-size gravel strata.3. The bidirectional arch buckle integrated technology which means the primary and secondary tunnels adopt the caven-PBA method at the same time in cross position of group large section tunnels is proposed, and additional beam elements solve initially the construction problem of cross position of underground complex cavern.更多还原