棒式光纤传感器在地下洞群模型试验中的应用

Application of FBG to 3D geomechanical model test of large underground caverns

地质力学模型试验是在复杂条件下进行大型地下洞室围岩稳定性分析的重要研究手段,能够真实地反映地质构造和工程结构的空间关系,准确模拟施工过程对厂房稳定性的影响以及岩体的破坏特征。双江口水电站地下洞群模型试验中采用预留孔径灌胶方式进行高精度的棒式光纤光栅(FBG)位移传感器的埋设,以便对洞室周边的位移进行量测,同时应用FLAC3D进行数值模拟比较。结果表明:棒式光纤光栅传感器量测方法解决了模型试验中内部变形小、量测精度要求高的问题,与数值模拟结果相吻合;试验中传感器埋设的方法是成功的,无论是开挖阶段还是超载阶段传感器均能有效地监测模型内部变形,揭示地下洞室群模型在开挖阶段和超载阶段的变形机制和破坏特征。

Geomechanical model test is an important research method to study the large underground caverns under complex conditions,this method can reflect the geological structure and powerhouse structure more truly,simulate the excavation of caverns which have influence on the stability of surrounding rock more precisely and reveal the failure characteristics of the rock.The 3D geomechanical model test of Shuangjiangkou large underground caverns is carried out.In the test,we choose the high precision FBG to measure the displacment of monitoring points and make a reservation pore and pour glue later to bury FBG.At the same time,we use the three-dimensional fast Lagrangian analysis of continua method to simulate the excavations,and make a comparison.The results show that：FBG solves the problem that the test has small deformation,but very high precision requirement.The results of the FBG agree well with numerical simulation results.In the test,it is successful to bury FBG.FGB measures the displacments of monitoring points effectively regardless of the excavation stage or the overload stage;the results reveal deformation mechanism and failure characteristics of the 3D geomechanical model.