川西海子山超固结土工程地质特性及成因机理研究

Research on Engineering Geological Characteristics and Genetic Mechanism of Over Consolidated Soil at Haizi Mountain in the West of Sichuan

川西海子山晚更新世冰川遗迹发育且保存完整,在某场地工程地质勘查中揭示,海子山冰川堆积物普遍具有固结较好、承载力较高的特点,含砾中、粗砂层承载力可达500～800 kPa,远高于其他成因的同类土,为超固结土。结合物探、钻探、详细的地面测绘、显微分析及孢粉分析,通过标贯及载荷试验、室内土工试验等,揭示区内低凹地段均有超固结土存在,区内超固结土具有低渗透性、低变形、高承载力等工程特性。超固结土是晚更新世古冰帽巨大荷载使冰川底碛排水固结到全新世时冰川消融卸载而成的特殊土体。

The glacier vestige during Late Pleistocene epoch on the Haizi Mountain in the west of Sichuan is developed and preserved completely. It is disclosed in an on-site engineering geological survey that the glacial deposits on the Haizi Mountain has the characteristics of good consolidation and high bearing capacity in general with the bearing capacity of the medium-size and coarse sand layers containing gravel up to 500 -800 kPa which is far more than that of the like with other genesis, so it is over consolidated soil. With geophysical prospecting, probe drilling, detailed ground mapping, microscopic and palynological analyses and through standard penetration test, loading test, and indoor geotechnical test, it is demonstrated that in the indented area of this region, there exists over consolidated soil which has the engineering characteristics of low penetrability, low deformability and high bearing capacity. This over consolidated soil is the special earth mass which is formed because the very large load of ancient ice cap during Late Pleistocene epoch causes the drainage of ground moraine to be consolidated till glacial ablation and unloading during Holocene epoch.