复杂受荷下盾构隧道原型结构试验平台的研发与实证

Development and demonstration of prototype test platform for shield tunnel linings under complex loading scenarios

盾构隧道结构在全寿命周期中往往将面临诸多复杂荷载状态,如注浆、偏载、偏转等非对称偏不利工况。为验证结构在这些复杂荷载状态下的适用性,探究结构力学性能,开展足尺原型结构试验研究往往是最为直接而有效的手段。既有原型试验主要关注隧道结构在简单对称荷载条件下的力学性能,鲜有关注复杂非对称荷载状态。为拓展原型试验的适用范围,提出了适用于不同断面盾构隧道结构的原型试验平台和用于模拟复杂荷载状态的试验荷载设计方法。该方法适用于任意加载点布置和液压站分组的试验系统,可对注浆、偏载、偏转等复杂荷载状态下结构响应进行精确模拟。通过类矩形盾构隧道、双圆隧道和圆形隧道的偏载原型结构试验研究,验证了试验平台和试验荷载设计方法的适用性。进一步针对试验关键参数的分析表明,控制目标权重系数的调整能有效满足不同的试验模拟要求;基于试验荷载设计方法优化的迭代算法能有效考虑计算模型或边界支承条件的非线性;环箍钢绞线和千斤顶的组合加载模式能将拟合误差水平降低至千斤顶加载模式的1/5,但需要删去部分加载点使试验荷载合理且适用;对于越复杂的结构和荷载,精确模拟结构状态需要的试验系统独立荷载组数越高,对试验平台的要求也越高。

During the entire life cycle of shield tunnel structures,there will always be various complex loading scenarios,including asymmetric and unfavorable conditions like grouting,eccentric loading,or rolling.The prototype structural tests are the most effective means to verify the applicability of the structures under such scenarios.However,the existing prototype tests predominantly focus on the mechanical behavior of tunnel structures under simple symmetric loading,while complex asymmetric loading scenarios are rarely addressed.To expand the application of the prototype tests,a prototype test platform suitable for the tunnel structures with any cross-sections is established.Additionally,a corresponding test load design method simulating the complex scenarios is also proposed,which is applicable to loading systems with any arrangement of loading points and hydraulic stations.To demonstrate the effectiveness of the test platform,the Quasi-rectangular tunnel,DOT(double circular)tunnel,and circular tunnel under the eccentric loading scenario are taken as examples.Further analysis of key test parameters reveals that the weight coefficients of control targets can be adjusted to meet different simulation requirements.The proposed test load design method allows for iterative modifications,effectively considering the nonlinearity of the model or boundary support conditions.By combining the hoop strand with the hydraulic jacks in the loading mode,the fitting error level can be reduced to 1/5 compared to the jacks-only loading mode,where some loading points need to be cancelled to make the design test load reasonable and applicable.For the accurate simulation of structural behavior under different loading scenarios,the structures with greater complexity and loading scenarios require a higher number of independent loading groups and more stringent requirements for the test platform.