Shuai Gao

Airborne LiDAR has been adopted as a powerful survey tool for overhead power transmission line (TL) cruising so that the operator can quickly search for, locate and eliminate the risk objects at the power line corridor scene. However, the TLs are moving objects, which positions are dynamically affected by working conditions (e.g. temperature variation, wind-induced conductor motion) while they are acquired by airborne LiDAR. The point clouds data acquired by airborne LiDAR only reflect the geometric relationship between the TL and its surrounding objects at the transient moment of the data acquisition. In order to overcome the shortcomings of the instantaneously acquired laser scanning data, this article presents an approach for simulating the dynamic TL shape under different working conditions based on mechanical computation of the overhead line. The proposed approach considers the tension variation of TL resulting from weather conditions, such as temperature, wind and ice, while simulates TL sag curve using the parabolic catenary equation combined with the tension. A performance evaluation was conducted over the TLs data with multiple voltage levels. Experiments results show that the proposed approach is effective for simulating the 3D shape of TL under different working conditions. The simulation error achieved was less than 0.65m and the maximum Diff-Ratio was about 1.57%. This provides a scientifically sound predicting and modeling approach for TL risk assessment and warning along the corridor.

The description of rock effective stress in CO₂‐water two‐phase fluid (CWTPF) is a key issue in the mechanical stability analysis of CO₂ geological sequestration. Related simulation studies often directly used the unsaturated effective stress models without verifying their applicability. In this study, we present a self‐developed hollow‐cylinder tensile tester and a corresponding experimental method to measure the fracturing pressure of sandstone in CWTPF. Based on the apparatus, we conducted tensile fracturing experiments of sandstone in CWTPF. We also carried out fracturing tests of sandstone saturated with water under different effective confining pressure to fit the function of the sandstone's fracturing pressure and effective confining pressure. Then, we selected seven typical unsaturated effective stress models and Finally, we compared the results from the prediction models and experiments to indirectly verify the applicability of these unsaturated effective stress models under CWTPF conditions. The results indicated that the model proposed by Bishop and Donald in 1961 could best describe the effective stress of the tested sandstone in tension fracturing behavior under CWTPF condition. © 2016 Society of Chemical Industry and John Wiley & Sons, Ltd