连拱隧道衬砌厚度不足对结构安全性的影响研究

为解决因衬砌厚度不足而诱发的连拱隧道结构裂损及安全问题，针对整体式曲中墙连拱隧道，通过相似模型试验，重点研究衬砌厚度不足条件下连拱隧道围岩压力特征、衬砌内力分布以及裂损演化规律。研究结果表明： 1)连拱隧道中墙墙角部位的弯矩最大，中墙墙角外表面产生裂缝,内表面结构压溃，裂损程度最为严重，为最不利位置。 2)衬砌厚度不足部位的边缘是衬砌薄弱截面，左线左拱肩存在衬砌厚度不足时，厚度不足位置右边缘的衬砌内侧开裂；左线左边墙存在衬砌厚度不足时，厚度不足位置上边缘的衬砌外侧开裂。 3)连拱隧道中墙顶部与拱腰接触部位出现较大的拉应力，衬砌厚度不足位置的改变对中墙顶部衬砌受力造成一定的影响，厚度不足位置对侧隧道中墙右上角部位的裂缝出现晚于拱顶裂缝，是连拱隧道结构破坏的重点区域。

Influence of Insufficient Lining Thickness on Structural Safety of Double arch Tunnel

The insufficient lining thickness often causes crack or damage to double arch tunnel structure and further threatens the tunnel safety. Thus, the surrounding rock pressure characteristics, distribution laws of lining internal force and crack of tunnel structure under condition of insufficient lining thickness of double arch tunnels with monolithic lined central walls are studied by similarity model test. The study results show that: (1) The maximum bending moment is located in the bottom of the middle wall, and cracks and crushing occur on the outer and inner face of middle wall corner with the most serious crack damage, which is the most unfavorable position. (2) The lining border with insufficient thickness is the weak zone, cracks would occur to lining inner face of right edge when the lining thickness of left arch shoulder of left line is insufficient, and those would occur to lining outer face of upper edge when the lining thickness of left arch shoulder of left line is insufficient. (3) Large tensile stress occurs to the connecting area between middle wall top and haunch, the variation of locations of insufficient lining thickness area would affect the stress state of the lining on the middle wall top, and the crack on the upper right corner of the middle wall, which is the key area of the lining failure, appears later than that at the crown on the opposite side of the lining with insufficient thickness.