土体冻融特性试验研究现状与思考

Advance and review on the experimental researches of the freezing and thawing characteristics of soils

冻融试验是获取冻土物理力学参数、评估冻土工程特性的重要手段。从冻土水热参数、力学参数、冻胀机制和融沉机制4个方面对土体冻融特性试验研究进行综述,对主要水热力参数的试验方法和试验设备进行汇总说明,对理论模型的发展过程及试验验证进行归纳整理。试验装置的变温控制性能是影响冻土试验数据质量的重要因素,但当前高精度冷却液循环控温设备的国产化程度较低,高性能冻融试验系统仍主要依赖进口。因此在开展冻土试验和理论研究的同时,对于试验设备的研发工作同样需引起重视。由神经网络–PID算法和热电制冷模块组成的固态控温系统可以解决试验装置的变温控制问题。固态控温系统的高变温控制性能具备模拟复杂冻结过程的能力。将其与新型传感技术结合,如光纤压力传感技术、线阵CCD扫描成像技术,可以为冻土研究提供新的试验方案,以此促进土体冻融机制研究,为我国寒区工程建设提供参考。

The freezing-thawing test is vital to obtain the physical parameters and to evaluate the engineering characteristics of frozen soils.In this paper,the experimental study on frozen soils is reviewed from four aspects:hydrothermal parameters,mechanical parameters,frost heaving and thaw settlement mechanisms.The main test methods and equipments of thermal-hydro-mechanical parameters are presented.The development and experimental verification of the theoretical models are summarized.The variable temperature control ability of the equipments is important for the data quality of frozen soil tests.However,the domestic manufacturing level of low temperature coolant circulation pumps with high pecision is immature in China.Freezing-thawing test systems with high performance are still mainly dependent on imports.Therefore,attention should be paid to the research and development of test equipments when the experiment and theoretical researches on frozen soils are carried out.The neural network-PID algorithm combined with the solid-state refrigeration system is capable to solve the problem of variable temperature control of test equipments.The high variable temperature control performance of the solid-state refrigeration system has the ability to simulate the complex freezing process.Combined with new sensing technologies,such as fiber optic pressure sensing technology and linear CCD scanning imaging technology,the solid-state refrigeration system can provide new experimental schemes for the frozen soil research.The improvement of the test technology can promote the research of freezing and thawing mechanism of soils and provide reference for the engineering construction in the cold regions of China.