Primary composition of experimental materials.

To utilize discarded shield residue and alleviate the shortage of subgrade filling, industrial wastes such as calcium carbide slag (CCS) and fly ash (FA) were considered to enhance the mechanical properties of the shield residue. A series of laboratory tests, including California Bearing Ratio (CBR) tests, unconfined compressive strength (UCS) tests, moisture content tests, pH tests, water stability tests, and dry-wet cycles tests were performed on discarded shield residue with additive contents. The results show that the UCS and CBR values enhanced significantly with the increase in curing time. However, the moisture content and pH of the stabilized soil exhibited a decreasing trend. The early UCS of CCS-FA stabilized soil is slightly lower than that of QL-FA stabilized soil. After 60 curing days, all stabilized soil exhibited a UCS value exceeding 1.9 MPa. In addition, the CBR values of CCS-FA stabilized soil were more than 8 times higher than those of the original shield residue. Furthermore, the water stability of CCS-FA stabilized soil is slightly better than QL-FA stabilized soil, especially at 7 days and 14 days. As for dry-wet cycles test, after the fifth cycle, the CCS-FA stabilized soil maintained overall integrity. The CCS can effectively replace QL to enhance the mechanical properties of shield residue as subgrade filling.为实现废弃盾构余渣的资源化利用、缓解路基填料供需短缺问题，本研究选取电石渣（calcium carbide slag, CCS）、粉煤灰（fly ash, FA）等工业固废作为改性添加剂，以改善废弃盾构余渣的力学性能。针对掺加不同比例添加剂的废弃盾构余渣，开展了一系列室内试验，涵盖加州承载比（California Bearing Ratio, CBR）试验、无侧限抗压强度（unconfined compressive strength, UCS）试验、含水率测试、pH值测定、水稳定性试验及干湿循环试验。 试验结果表明：固化土的无侧限抗压强度与加州承载比均随养护龄期延长显著提升，而固化土的含水率与pH值则呈逐渐下降趋势。电石渣-粉煤灰固化土的早期无侧限抗压强度略低于QL-FA固化土，但养护至60天后，所有固化土的无侧限抗压强度均超过1.9 MPa。此外，电石渣-粉煤灰固化土的加州承载比相较原始盾构余渣提升8倍以上。 进一步来看，电石渣-粉煤灰固化土的水稳定性略优于QL-FA固化土，在养护7天与14天时表现尤为显著。干湿循环试验结果显示，经5次循环后，电石渣-粉煤灰固化土仍保持整体结构完整。综上，电石渣可有效替代QL，作为路基填料改性剂提升废弃盾构余渣的力学性能。