基于D-P准则的盾构隧道围岩与衬砌结构相互作用分析1）

在进行盾构隧道管片衬砌结构载荷计算时，常采用全土柱或压力拱理论计算围岩松动压力，但当盾构隧道面临深埋条件且需计入形变压力时，该方法难以适用.鉴于此，基于Drucker-Prager屈服准则，推导了考虑渗流效应影响下围岩与衬砌结构相互作用的弹塑性解析解，给出了围岩弹、塑性区应力与位移、塑性区半径等关键参数与支护阻力间关系的解析式.阐述了上述解析结果在确定衬砌结构载荷中的应用，即建立围岩与衬砌结构静力平衡状态并求二者对应曲线的交点.进一步地，考虑接头引起管片衬砌结构整体刚度降低对围岩与衬砌结构相互作用的影响，引入刚度折减系数，并在衬砌结构围岩压力确定中对施工期流固耦合效应的影响和渗流力对衬砌结构支护特性曲线的影响进行了简化处理.最后，通过算例将解析解与水下盾构隧道载荷实测值和数值计算值进行了比较.结果表明：用解析方法得到的施工期和稳定期的管片衬砌结构围岩压力比现场实测值分别大28%和12%，稳定期围岩压力比数值计算值大5%，可为类似工程的设计施工提供一定的参考价值.

THEORETICAL ANALYSIS OF INTERACTION BETWEEN SURROUNDING ROCKS AND LINGING STRCTURE OF SHIELD TUNNEL BASED ON DRUCKER-PRAGER YIELD CRITERIA

In calculating the load for segment lining structure of shield tunnel, the soil column or pressure arch theory are often used to describe surrounding rock loosening pressure.But when it comes to the deep-buried condition and the deformation pressure should be calculated, this method is considered as unreasonable and is difficult to apply.In view of this, based on the Drucker-Prager yield criterion, an analytical elasto plastic solution is derived for the interaction between surrounding rock and lining structure considering the influence of seepage effect, and the formula of the relationship between the support pressure and some key parameters such as the stress and displacement of surrounding rock elastic and plastic zone as well as the radius of the plastic zone is given.The analytical results can be applied in the determination of the load of the lining structure by establishing the static equilibrium state of the surrounding rock and the lining structure and finding the intersection point of the two curves.Further, rigidity reduction factor is induced to equivalent considering the influence of the overall rigidity decrease of assembled segment liner for the existence of joints to the interaction of surrounding rock and lining structure.In the load determination, the influence of the fluid-solid coupling effect during construction and seepage force on support characteristic curve of lining structure is also simplified considered.Finally, an engineering instance of underwater shield tunnel is introduced to compare the calculated load with the measured value and numerical simulated value.The results show that the caculated analytical load values of segment lining structure are greater by 28% and 12% comparing to measured values during the construction period and the stable period, and are greater by 5% comparing to numerical simulated value during the stable period, respectively.The research results of this paper can provide some reference for the design and construction of similar projects.