Cui Guangqin, Zhang Hang, Ma Chenguang, Zhang Xiaoli, Shao Hong
The Inner Mongolia University of Science and Technology School of Civil Engineering, Baotou, 014010, China.
Zhongdi Yingang Construction Group Co, Baotou, 014010, China.
Sci Rep. 2024 Dec 28;14(1):31459. doi: 10.1038/s41598-024-83133-9.
In the course of pipe jacking construction, the carrying-soil effect frequently arises, influenced by factors such as excavation unloading, ongoing disturbance from successive pipe sections, and the progressive accumulation of soil adhesion. The pipe jacking slurry serves as a critical agent for friction reduction and strata support, essential for the secure advancement of the construction process. This study introduces the Microbial-Induced Calcium Carbonate Precipitation (MICP) technology into the realm of pipe jacking slurry, aiming to enhance its friction-reduction capabilities and the stability of the soil enveloping the pipe. An optimal MICP-slurry formulation was determined using the uniform design approach. Subsequent model tests were carried out to assess the friction-reducing efficacy of the MICP-slurry, while the mechanism by which the MICP-slurry reinforces strata stability was investigated through soil mechanics and scanning electron microscopy (SEM) analyses. The findings indicate that the optimal MICP-slurry composition is as follows: bentonite: sodium carboxymethyl cellulose: soda ash: polyacrylamide: xanthan gum = 12%: 0.31%: 0.36%: 0.25%: 0.54%. The MICP-slurry achieves a 42.2% reduction in the friction coefficient between the test block and the sand. In comparison with the untreated sample, the cohesion of the MICP-treated sample is enhanced by 38.12%, and the internal friction angle increases by 14.01%. SEM examination reveals that the calcium carbonate crystals precipitated by the MICP-slurry within the soil populate the pores, increase the inter-particle bite force, and bolster the soil's mechanical characteristics.
在顶管施工过程中，受开挖卸载、后续管节持续扰动以及土黏附作用逐渐累积等因素影响，常出现带土效应。顶管泥浆是减少摩擦力和支撑地层的关键介质，对施工过程的安全推进至关重要。本研究将微生物诱导碳酸钙沉淀（MICP）技术引入顶管泥浆领域，旨在提高其减摩能力以及增强包裹管道的土体稳定性。采用均匀设计法确定了最佳的MICP泥浆配方。随后进行模型试验以评估MICP泥浆的减摩效果，同时通过土力学和扫描电子显微镜（SEM）分析研究MICP泥浆增强地层稳定性的机理。研究结果表明，最佳的MICP泥浆组成如下：膨润土：羧甲基纤维素钠：纯碱：聚丙烯酰胺：黄原胶 = 12%：0.31%：0.36%：0.25%：0.54%。MICP泥浆使试验块与砂土之间的摩擦系数降低了42.2%。与未处理的样品相比，经MICP处理的样品的黏聚力提高了38.12%，内摩擦角增加了14.01%。SEM检查显示，MICP泥浆在土壤中沉淀的碳酸钙晶体填充了孔隙，增加了颗粒间咬合力，并增强了土壤的力学特性。
