Comparison and Analysis of Measured Data from Flexible Inclination Meters and Other Monitoring Devices

1. Overview

Flexible inclination meters are important automatic monitoring devices for the deformation of dams and slopes, widely used both domestically and internationally, and increasingly favored by engineering management units. However, there is limited reporting on ultra-long flexible inclination meters and their synchronous comparison with various other types of deformation instruments, both domestically and internationally. To verify the effectiveness of ultra-long flexible inclination meters and compare them with various similar instruments, this article conducts actual engineering tests to validate the advantages of this type of domestically produced flexible inclination meter.

Through extensive investigation and research, the application engineering case selected is the monitoring of deep displacement at the Jinhua-Wenzhou Railway landslide in Qingtian County. The data comparison analysis equipment includes flexible inclination meters, GNSS, and total stations.

The landslide at the Xiaoge Liao in Qingtian County is identified as the sixth large-scale rockslide in the country, characterized by layered and overall displacement. The front edge of the sliding mass is suspected to be a traction landslide, with a thickness of 20 to 105 meters and a volume of approximately 11 million cubic meters. The secondary structures and joint fractures in the landslide area are well developed, with fragmented rock and complex geological conditions, posing a Grade I hazard level. If this landslide collapses, it could result in the interruption of the Ou River, burial of the Jinhua-Wenzhou railway line, and flooding of upstream towns. To understand the current state of the landslide in real-time and ensure the safe operation of the Jinhua-Wenzhou Railway and the safety of surrounding residents, as well as to provide a scientific basis for emergency rescue operations, the safety monitoring unit, China Railway Fourth Survey and Design Institute Group Co., Ltd., has adopted Huasu Measurement Control flexible inclination meters for automated monitoring and early warning of three existing inclination holes.

2. Instrument Equipment Layout

The equipment is distributed in the landslide monitoring area of Xiaoge Liao in Qingtian County, Lishui City, Zhejiang Province. The distribution and detailed layout of the equipment are shown below:

Figure 2-1: Overall Equipment Distribution Map

Figure 2-2: Detailed Equipment Distribution Map

3. Data Comparison Analysis

Comparison of monitoring data changes from three types of equipment: flexible inclination meters, total stations, and GNSS (comparing cumulative displacement change process lines over the same period).

Figure 2-3: Comparison of Monitoring Data Changes from Flexible Inclination Meters, Total Stations, and GNSS

4. Conclusion

The measured comparison data indicate:

1.GNSS Static Monitoring Data

The measured displacement from GNSS static monitoring is 47.9 mm, while the flexible inclination meter measures 45.4 mm, with a data difference of 2.5 mm.

2.Total Station Monitoring Data

The two total station measurement points (3-8 and 3-9) recorded displacement values of 52.7 mm and 52.5 mm, differing by about 7 mm from the flexible inclination meter and about 5 mm from GNSS point 3-9.

3.Test Results

The comparison analysis of the monitoring data from these three types of testing equipment indicates that the trends and values of deformation monitoring are generally consistent across all devices.