Objective At present, researches on the disposal of shield muck in China mainly focus on muck reduction and resource utilization, and a whole-process disposal mode is not yet established. Therefore, it is necessary to study the treatment and reuse technology, and improvement measures for Chengdu Metro shield muck issues.
Method Taking Civil Engineering Section 4 and Section 8 of Chengdu Metro Line 19 Phase Ⅱ project as examples, on-site sampling is conducted on the shield muck produced by sand-mud separation and filter press equipment. Indicators such as leaching toxicity, pollutant mass fraction, and soil mechanical parameters are tested. Based on the process flow and material balance analysis, problems in the disposal process and resource utilization potential are identified, and effective suggestion and improvement measures are proposed.
Result & Conclusion The disposal of shield muck from Chengdu Metro basically achieves the goal of Three Orientations (muck reduction, resource utilization and harmless treatment). However, there still exist the following prominent challenges: low popularity of disposal equipment, coupled with limited intelligence and modularization levels; a pH range of 9.3-11.6 in filter cakes after pressure filtration, tending to impair soil nutrient availability; and the insufficient degree of resource reuse. To address the above issues, corresponding improvement measures are proposed, including source reduction, resource utilization of filter cakes, harmless treatment of pollution sources, dynamic economic benefit evaluation, and relevant supporting policies.
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