Exploration of Efficiency Inspection and Maintenance Management for the Soil Anchors on Freeway Slopes

• Main Authors: CHENG-YU HUANG, 黃政裕
• Other Authors: SAO-JENG CHAO
• Format: Others
• Language: zh-TW
• Published: 2019
• Online Access: http://ndltd.ncl.edu.tw/handle/am45p3

碩士 === 國立宜蘭大學 === 土木工程學系碩士班 === 107 === In Taiwan, the landforms are mainly dominated by mountains and hills. Many road sections of the National Highway are impossible to avoid problems such as slope excavation or slope filling. In order to increase the safety of the slope, various slope protection methods are used to stabilize the slope, especially the soil anchor technique is the most common. In recent years, some of the soil anchors are no longer able to exert original efficiency with time increasing, thus the effectiveness of soil anchors is highly concerned. Therefore, the Highway Bureau follows the regulations of the highway maintenance manual to carry out the evaluation for the soil anchors every 4-5 years, through the appearance inspection, the component inspection, and the lift-off test. To date, the soil anchors on the highway slopes have been evaluated twice. This study compares the results of the two evaluations for the soil anchors, as well as the residual loads of the soil anchors on cutting slope and embankment slope currently. In addition, the soil anchors have the common problem of rust at present, and caused several slope disasters because of the stranded steel wire corrosion cracks. This study works on the soil anchor maintenance method, which is applied to the external and internal protection of the soil anchors to extend the service life of them. For example, the method of protecting the anchor head adopts a new material, namely rust preventive gel, to prevent the water leakage and wire corrosion, with the aid of 93 test soil anchors on the highway slope and check the efficiency every half year to assess the effectiveness of rust preventive gel. This study also introduces the concept of safety potential into the anchored slope, using the QGIS program to draw the slope potential map to evaluate the portion may be harmful. The hazardous region can thus be paid attention and maintained in advance to improve safety maintenance management. Finally, in order to understand the safety of the embankment slope, this study employs the PLAXIS finite element program to perform the stability analysis of an embankment slope. The safety factor and the failure surface of the anchored embankment slope are evaluated for ordinary, heavy rain and earthquake conditions, with the residual load attenuation from 100% to 0%. This study validates the suitability of using the PLAXIS program to simulate anchored embankment slopes. It is also concluded that the safety factor of the embankment slope is reduced with the attenuation of residual loads of the soil anchors as expected.