兰新客专第四系上更新统胶结层成因分析及处理措施

兰新客专DK855+900~DK870+933段位于河西走廊中西端,在第四系上更新统洪积层中夹有胶结层,根据勘探及开挖揭示情况,查明了胶结层的分布及埋藏特征,胶结物主要为钙质,近地表还有硫酸盐胶结,根据岩性可分为黏性土（粉土）胶结层、砂土胶结层、圆砾土胶结层三种类型,其成因主要为胶结矿物的淋滤、聚集、凝结、结晶及胶结。通过调查及取样试验,胶结层具有岩石或半成岩性质,具较高的抗压强度、较强的抗崩解、抗软化及抗风化等工程特性,与周围土层性质有显著差异,岩土施工工程分级Ⅳ~Ⅴ级,地基应采取针对性的处理措施。

Genesis Analysis of Quaternary Pleistocene Series Cemented Layer along Lanzhou-Xinjiang Passengers Dedicated Line and the Treatment Measures

DK855+900~DK870+933 section of Lanzhou-Xinjiang PDL locates in the midwest of Hexi Corridor, where the quaternary pleistocene series diluvial formation sandwiches cemented layers. According to the situations revealed by the prospecting and excavation, the cemented layers were found out to be distributed and buried as such that the cementing material is calcium mainly with sulfate cemented near the ground surface. They may be classified into three kinds according to the lithologic character, i.e.clay soil (silt) cementation, sand cementation and round gravel soil cementation. The genesis thereof mainly are leaching, aggregation, coagulation, crystallization, and cementation of cementing minerals. The investigation and sampling tests disclose that the cemented layers has the performance of rock or hypabyssal rock, showing high compressive strength, strong resistance to disintegration, softening and weathering and other engineering properties. It has obvious difference to the surrounding soil layer, and the grade of geotechnical construction is IV~V. The countermeasures should be used to treat the foundation.