Evaluation of the effectiveness of monitoring the axial force of anchors based on sensor-enabled piezoelectric geocable (SPGC)

Abstract

Anchor rods are typically used for support. The axial force of anchor rods changes owing to the stress change of the rock and soil body on the slope; therefore, monitoring the axial force enables the early detection of landslides. However, the accurate monitoring of the axial force change of bolt faces many challenges, such as high monitoring cost and limited monitoring range. Therefore, a new, efficient, and cost-effective monitoring technology needs to be developed to address these challenges. In this study, a sensor-enabled piezoelectric geocable (SPGC) with an impedance–strain effect was used, which has the advantages of low cost, distribution, and quantization. The SPGC was attached to a bolt to form a sensor-enabled piezoelectric anchor rod (SPAR). SPAR tensile tests with different groove sizes, loading rates, and SPGC lengths were performed using the displacement loading method. The test results show that the normalized impedance curve of the SPAR has a good correspondence with the stress–strain curve and decreases with an increase in the tensile stress of the SPAR. The dimensions of the notch of the SPAR affect the failure speed of the SPGC in tension, and the optimal size of the notch of the SPAR is a semicircle with a diameter of 3 mm. An increase in tensile rate accelerates the monitoring failure of the SPAR, whereas an increase in SPGC length accelerates the decline rate of the normalized impedance curve and the monitoring failure of the SPAR. The SPAR can accurately monitor the axial stress change and failure process of the bolt, which can provide technical support for the distributed deformation monitoring of the slope, and is expected to provide a new solution for the monitoring and early warning of slope engineering.