川中红层不均匀膨胀特性及对路基上拱影响机制OA
Non-Uniform Swelling Characteristics of Red Beds in Central Sichuan and Their Mechanism on Subgrade Upheaval
川中红层地区高速铁路路基持续上拱变形问题对运营安全构成了长期而潜在的威胁.依托实际工程,开展川中红层微-细观测试、三向膨胀特性试验以及原位分层上拱监测,从不同尺度上分析其矿物组成、微观结构、岩层结构差异引起的不均匀膨胀特性,探究其对路基长年上拱的影响机制.研究结果表明,泥岩与砂岩互层产出的川中红层中存在多组水平层理面,各岩层膨胀性黏土矿物含量差异很大,导致其膨胀力高、值域范围宽,差值应力可达 1.5 MPa以上,加上微观结构上矿物颗粒的择优取向,使得垂直于层理方向的膨胀率明显大于平行于层理方向,各向异性膨胀率系数达 0.34～0.71,这种不均匀膨胀效应足以产生宏-细裂隙并沿水平层理方向扩展.结合川中红层路基上拱实测数据分析,运营 1～2 年内路基上拱较快但速率逐渐减小,运营 2 年后路基上拱速率逐渐稳定在5～11mm/a,并紧随雨-旱季变化呈周期性波动.主要上拱层位并非发生于浅表层,而是受控于与外界存在水力联系的岩层节理、裂隙面的分布,最大上拱深度可达 15 m.综合来看,川中红层不均匀膨胀易产生裂隙并沿层理面扩展,并在环境周期性变化影响下持续演化,是导致路基持续多年非收敛上拱变形的重要机制.
The continuous upheaval deformation of high-speed railway subgrades in the Red Bed area of central Sichuan poses a potential long-term threat to operational safety.Based on an actual engineering project,micro-and meso-scale tests,triaxial swelling tests,and in-situ layered upheaval monitoring of the Red Beds in central Sichuan were carried out.The study analyzed,across multiple scales,the non-uniform swelling characteristics caused by differences in mineral composition,microstructure,and rock-layer structure,and explored their mechanism on the long-term subgrade upheaval.The results showed that the Red Beds in central Sichuan,composed of interbedded mudstone and sandstone,contained multiple sets of horizontal bedding planes.The expansive clay mineral content varied greatly among the rock layers,resulting in high swelling pressures with a wide range of values,where the differential stress could exceed 1.5 MPa.Combined with the preferred orientation of mineral particles in the microstructure,the swelling strain perpendicular to the bedding direction was significantly greater than that parallel to the bedding direction,with an anisotropic swelling coefficient ranging from 0.34 to 0.71.This non-uniform swelling effect was sufficient to generate macro-and micro-cracks and to promote their propagation along the horizontal bedding planes.Analysis of the field monitoring data on Red Bed subgrade upheaval showed that the upheaval developed rapidly during the first 1-2 years of operation,although the rate gradually decreased.After two years of operation,the upheaval rate stabilized at 5-11 mm/a and exhibited periodic fluctuations corresponding to alternating rainy and dry seasons.The primary upheaval stratum did not occur in the shallow surface but was controlled by the distribution of joints and fractures hydraulically connected to the external environment,with the maximum upheaval depth reaching 15 m.Overall,the non-uniform swelling of the Red Beds in central Sichuan tends to generate cracks that propagate along bedding planes and continuously develop under the influence of periodic environmental changes.This process constitutes an important mechanism for the sustained,non-convergent upheaval deformation of the subgrade over many years.
李洋;余飞;陈善雄;黄康;戴张俊
中国铁路成都局集团有限公司,成都 610082中国科学院武汉岩土力学研究所,武汉 430071中国科学院武汉岩土力学研究所,武汉 430071中国科学院武汉岩土力学研究所,武汉 430071中国科学院武汉岩土力学研究所,武汉 430071
交通工程
高速铁路路基川中红层不均匀膨胀分层上拱节理裂隙
high-speed railwaysubgradeRed Beds in central Sichuannon-uniform swellinglayered upheavaljoints and fractures
《铁道标准设计》 2026 (1)
54-62,9
国家自然科学基金项目(42172308)湖北省重点研发计划项目(2022BAA036)
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