The Mechanical Properties Test Of Artificial Frozen Soil And Project Application In Tianjin

With the massive construction of Tianjin subway, the application of artificial freezing method has been widely used in the hole of shield and contact channel excavation project. But for different soil in Tianjin region, lack the systematic experimental studies on artificial permafrost. The related specifications and experience of design and construction are referring to Shanghai region, inevitably caused some security risks and economic waste.In this paper, relying on the construction of Tianjin Metro Line No. 5 and 6 contact channels, a full investigation to the soil profile of Tianjin urban area was made. Different area drillings contains all of the soil conditions in Tianjin. Research on the strength characteristics of the artificial permafrost was carried out by indoor experiments.In chapter one, application overview of artificial freezing method in the city subway contract channels was summarized. the current research of uniaxial compressive strength properties, triaxial shear strength characteristics, flexural strength properties and numerical simulation in contract channel excavation was Investigated, the main content of this paper was pointed out.In chapter two, the experimental studies of uniaxial compressive strength properties of artificial frozen soil were carried out in different temperatures, different soil, different water content and different salt content. The uniaxial unconfined compressive strength of artificial permafrost were analyzed system in this part.In chapter three, experimental research of triaxial shear strength characteristics of artificial frozen soil were carried out. The strength index in different soil, different temperatures, different water content and different salt content was obtained to provide the basis for parameter selection for numerical simulation later.In chapter four, experimental research of flexural strength characteristics of artificial frozen soil were carried out. Flexural strength variation in different temperatures and moisture was obtained. Using the new test equipment, make up for the lacking of research in this field blank. The obtained test results can provide a basis for the design of Tianjin underground permafrost engineering.In chapter five, as to practical engineering, a two-dimensional finite element model was established to simulate the construction process. The selection and comparative analysis of the model parameters was based on the results of experimental research above, making numerical simulation more realistic.