地下综合管廊穿越地裂缝的力学响应及预警标准研究

Mechanical response and early warning standard of the underground cracks in the underground utility tunnels

以西安幸福林带地下综合管廊工程为研究载体,基于数值分析对穿越该工程的3条主地裂缝不同地裂缝错动量条件下的地表变形、管廊结构变形、应力及管廊底部脱空情况进行深入研究,进而提出管廊施工期内的预警指标、给定建议控制值及建议对应预警等级。结果表明:管廊与地裂缝斜交时,随地裂缝错动量增大,地表竖向沉降量与管廊错动量总体均呈增大趋势;其与地裂缝斜交角度越小,偏离变形缝距离越远,造成的拉应力越大;当接触压力为0时,上盘管廊结构下部会产生脱空情况。在综合管廊穿越地裂缝设计及运营管理中,应对地表竖向沉降、管廊结构应力、地裂缝位错量、接触压力4项指标进行实时监测,以便达到预警等级对应的控制值时及时做出预警响应,防止工程事故的发生。

The purpose of this paper is to solve the technical problems of the early safety warning for the underground utility tunnel based on the numerical simulation,a technical problem to be caused by the ground changing activities.To achieve the purpose,we have established an analysis model for the underground utility tunnel project obliquely crossed to the 3 ground fissures with the numerical simulation method.Taking the underground utility tunnel project of"Xingfu Lindai"(literally indicative of the Fortunate Forest Site)in Xi’an as the case study sample,we have first of all managed to set up a corresponding finite element model according to the relevant parameters,then,analyzed and examined the surface change,the change of the underground utility tunnel structure,the structural stress and the bottom emptiness of the underground utility tunnels.And,finally,we have proposed the warning indicators of the corridor with the control values and corresponding warning levels.The research results indicate that,when the underground utility tunnel and the ground fissures turn to be oblique,the ground subsidence would grow up with the increase of the ground fissure dislocation.Among them,the increase of the surface subsidence of the upper wall of the ground fracture would bring about a significant increasing trend,whereas the footwall subsidence may bring about a gentle deformation inclination.The dislocation of the ground fissures will also experience an up-&-down structure displacement,and simultaneously,the lower part of the upper underground tunnel will get to be empty or inner-holy.In the design and operation management of such underground utility tunnels across the ground fissures,it would be of extreme importance for the 4 indicators to be monitored timely and sufficiently,that is,careful monitoring practice over the surface vertical settlement,the structural stress of the underground utility tunnel,the dislocation of ground fissures and the contact pressure in the process of the construction of the underground utility tunnel crossed to the ground fissure.When the4 indicators become obvious enough to reach the stage of the early warning control,they would grow to respond promptly to prevent from the likely collapse accidents with the engineering process going on.