逆断层错动作用下双仓管廊结构力学特性和抗断设计研究

Mechanical properties and fracture resistance of double-box undergroundutility tunnel structure under reverse fault dislocation

断层蠕滑错动和地震作用对穿越断层及其上覆土层的浅埋地下结构的破坏是极其严重的。通过开展节段双仓管廊结构穿越45°逆断层的1∶30室内相似模型试验,对双仓管廊结构的位移、应变和接触压力分布规律等主要参数开展实时监测,并结合结构的渐进破坏过程、破坏模式和分布特征进行深入分析,以清晰揭示逆断层错动作用下节段双仓管廊结构的力学响应规律和致灾机理。结果表明:柔性接头可较好地释放断层蠕滑错动产生的能量和强制位移,并减小施加在结构上的弯曲剪切复合作用。节段衬砌结构的相邻节段影响较小,仅在C~E块的接头处出现局部破坏,避免了结构出现整体坍塌。上盘区域内管廊结构的位移变化明显。靠近断层面的双仓管廊结构的内力响应显著,尤其是70~120cm管廊结构破坏严重,应作为重点设防区域。逆断层错动完成后,双仓管廊结构易出现张拉和压缩破坏,其开裂破坏形式主要有裂缝、环间错台和剥落掉块。可见采用柔性接头措施可有效提高穿越断层的地下结构的抗断性能和震后保通能力。

Fault creep-slip dislocation and seismic action can cause significant damage to shallowly buried underground structures crossing faults and the overlying soils.The laboratory tests for the segmental double-box underground utility tunnel crossing a 45°re-verse fault were carried out on a 1:30 model.The main parameters of the double-box un-derground utility tunnel structure,such as displacement,strain,and contact pressure distri-bution,were measured in real-time.The progressive failure process and the failure mode and distribution of the structure were analyzed in-depth,so that the mechanical response law and disaster mechanism of the double-box underground utility tunnel under the reverse fault can be clearly revealed.The results indicate that flexible joints shall be more effective in dissipating the energy and forced displacement generated by fault creep-slip dislocation and in reducing the combined bending-shear actions on the structure.The impact of neigh-boring sections on the segmental lining structure is small,and only local damage occurs at the joints of the C-E blocks,preventing the overall collapse of the structure.The displace-ment change of the double-box underground utility tunnel structure in the hanging wall area is noticeable.The internal force response of the double-box underground utility tunnel struc-ture near the fault is prominent.In particular,the damage to the underground utility tunnel structure in the range of 70-120cm is severe and should be fortified particularly.After com-pletion of reverse fault dislocation,the double-box underground utility tunnel structure is vulnerable to tensile and compressive damage.The main cracking damage are in the forms of cracks,inter-ring misalignments,and block spalling.Hence,the use of flexible connection measures can effectively enhance the fracture resistance of the underground structure during and maintain traffic access after an earthquake.