Abstract: Objective: Taking the Hangzhou to Lin’an Intercity Railway project (Hangzhou Metro Line 16) as an example, the exploration and practice of the compactness detection behind the shield tunnel segment wall in weathering rock stratum during rail transit project construction is introduced. The segment backwall compactness detection for shield tunnel in weak weathering, medium weathering, and strong weathering geological strata is analyzed to provide a basis for tunnel backwall grouting and operational deformation assessment. Method: Onsite testing is carried out using the tapping detection method, ultrasonic imaging method, and geological radar detection method, and the geological radar detection method is determined through comparative selection based on the comprehensive reference of detection result reliability, work efficiency, and detection cost. Result & Conclusion: Through experimental comparison, the geological radar detection method is adopted to conduct a fullline inspection of the shield tunnel and mining method tunnel of Hangzhou Metro Line 16. The comparison and verification of the detected results with the actual grouting compactness behind the dismantled segment wall shows that there is good consistency between the detected and actual conditions, and no significantly spatial or serious grouting noncompactness or voids are found. The segment backwall compactness detection method for shield tunnel in weathering rock stratum achieves the expected results and meets the expected objectives.