Expand 1000 words according to the following points: The main points are: Convergence is the deformation of the surrounding rock to the center of the tunnel. It is measured as the displacement between two points on the inner wall. Accurately measuring convergence is important for judging rock stability, determining support timing, calculating final displacements, and assessing initial support adequacy. After excavation and blasting, test piles are buried along the arch wall for convergence measurement. A baseline is laid in the tunnel and surveyed after each round of excavation. The digital convergence meter is used to measure convergence by: Recording the ambient temperature Correcting the temperature deformation of the steel ruler Taking the sum of the steel ruler reading and the digital display reading as the baseline length Computing the convergence from the difference of the measured values. The vault settlement is the absolute vault settlement. Settlement speed is the amount per unit time. For horizontal formations, shallow buried depths, and low consolidation formations, vault settlement measurement is more important than convergence. Provide basic data to ensure safety and quality and guide construction. The pre-buried test piles are installed on the vault after excavation. Holes are drilled and stakes inserted, then anchored. The instrument is used to take measurements from an external or internal reference point to the measuring part prior to installation. Measure Settlement: Hang steel ruler vertically from vault hook Take steel ruler reading after temperature correction Calculate relative vault elevation Repeat measurements over time to obtain vault settlement values. In conclusion, convergence and vault settlement measurements using test piles, instruments and digital gauges provided important data on surrounding rock deformation to guide support design, timing and construction procedures. These measurements ensure the safety and quality of the tunnel structure throughout the construction process Please repeat the request first, then give your response.
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