高土石坝变形监测的监测管选型研究

Lectotype Study of Monitoring Tube for Deformation Monitoring of High Earth Rock-fill Dam

在土石坝分布式光纤变形监测技术中,监测管是光纤与坝体间力-光转换的媒介,它需要适应土石坝围压大、变形量大等特点。据此,采用分段刻槽的ABS管作为光纤应变传递载体的监测管方案,建立坝料-监测管复合体的三维非线性有限元模型,并通过坝料-监测管的大型土工三轴试验验证了该数值模型的有效性。基于该数值模型,研究了监测管在最不利受力情况下的应力分布,以检验其在高围压下的适应性。结果表明,ABS管具有较高强度,可适应300m级高土石坝的高应力状态。研究成果可为土石坝的变形监测提供参考。

In deformation monitoring of earth rock-fill dam based distributed optical fiber technology, monitoring tube is the mechanics-optics conversion medium between optical fiber and dam body, which needs to accommodate the features of earth rock-fill dam, such as high confining pressure and large deformation, etc. The ABS tube with segmented grooves was designed as the intermedium for strain transfer. To verify the feasibility of this design scheme, the 3D nonlinear FEM model of dam material and monitoring tube complex was presented to simulating the mechanical behavior of monito- ring tube in various cases. This FEM model was firstly verified by large-scale tri-axial test. Based on this FEM model, stress distribution of monitoring tube under the most unfavorable conditions was simulated for checking its applicability in the case of high confining pressure. The results show that the strength of ABS tube is higher enough to fit the high stress condition in 300 m level high earth rock fill dam. This research can provide a reference for deformation monitoring of earth rock-fill dam.