Xu Youjun, Li Zhenyu, Chen Zhigang
School of Civil Engineering, Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia 014010, China.
University Urban Underground Engineering Research Center of Inner Mongolia Autonomous Region, Inner Mongolia University of Science and Technology, Baotou, Inner Mongolia 014010, China.
ACS Omega. 2024 Dec 10;9(51):50809-50819. doi: 10.1021/acsomega.4c09466. eCollection 2024 Dec 24.
With its advantages of high cross-sectional utilization, shallow depth, and uninterrupted surface road traffic, the pipe-jacking method has been widely used in underground passages, metro stations, and other projects. However, this leads to a large volume of pipe-jacking waste soils that must be processed. Pipe-jacking waste soils are different from shield-tunneling waste soils. Therefore, it is not appropriate to simply use the same treatment method for shield-tunneling waste soils in the treatment of pipe-jacking waste soils. In this study, pipe-jacking waste soil samples were improved with 7% polyacrylamide (PAM) and 12% sodium-based bentonite solutions, with good performance being achieved. Based on this, quick lime and fly ash were used in the solidification of pipe-jacking waste soils, and experiments with different solution concentrations and solidification material additions were conducted, involving tests of compression, freeze-thaw cycling, wet-dry cycling, and microstructure. The results indicate that within the ranges of PAM and sodium-based bentonite addition ratios applied in this study, the solidification effects of quick lime and fly ash will not be significantly reduced during the improvement processes of pipe-jacking waste soils under balanced earth pressure conditions. Instead, it was found that there was an increase of up to 16% in the strength of pipe-jacking waste soils. Structural compactness can be primarily enhanced by gelatinous PAM, while sodium-based bentonite can promote the formation of hydrated colloids (such as C-S-H) and fill soil pores with hydrated gelatinous bentonite particles, thereby enhancing soil stability.
顶管法具有横断面利用率高、深度浅、地面道路交通不受影响等优点，已广泛应用于地下通道、地铁站等工程。然而，这导致产生大量必须处理的顶管废弃土。顶管废弃土与盾构隧道废弃土不同。因此，在处理顶管废弃土时简单采用与盾构隧道废弃土相同的处理方法是不合适的。在本研究中，用7%的聚丙烯酰胺（PAM）和12%的钠基膨润土溶液对顶管废弃土样进行改良，取得了良好的效果。在此基础上，采用生石灰和粉煤灰对顶管废弃土进行固化，并进行了不同溶液浓度和固化材料添加量的试验，包括压缩、冻融循环、干湿循环和微观结构试验。结果表明，在本研究应用的PAM和钠基膨润土添加比例范围内，在平衡土压力条件下，顶管废弃土改良过程中生石灰和粉煤灰的固化效果不会显著降低。相反，发现顶管废弃土的强度提高了高达16%。凝胶状PAM可主要增强结构致密性，而钠基膨润土可促进水化胶体（如C-S-H）的形成，并用水化凝胶状膨润土颗粒填充土壤孔隙，从而提高土壤稳定性。
