考虑热交换作用的桩基承载力特性研究

Study on Bearing Capacity of Pile Foundation Considering the Heat Exchange Effect

针对现行热交换桩承载力设计和计算中无法考虑温度的影响,通过开展不同温度下土的三轴剪切试验,获得其c,φ值,再建立热交换桩-土有限元模型,并利用静载试验结果验证模型的正确性,进而讨论了桩的运行温度及土的c,φ值对单桩极限承载力的影响,从而对热交换桩加热运行后的承载力特性进行研究。结果表明:随温度的升高,黏性土的c,φ值均有所降低,土的强度下降;桩体在加热运行过程中,其极限承载力有较大幅度的提高,且温度越高,单桩极限承载力也越大;温升引起的地基土强度降低对单桩极限承载力影响较小。可为热交换桩承载力设计和计算提供理论依据。

Ignoring the influences of temperature in the current design and calculation of bearing capacity of heat exchanger piles is insufficient,accordingly,in this paper the shear strength test was carried out firstly on the clay at different temperatures,and the c,φ values of the clay are obtained. Then,the finite element model of heat exchanger piles and soil is presented and verified by result of static load test for a single pile. Furthermore,the influence of operation temperatures and values of c,φ on the ultimate bearing capacity of a single heat exchanger pile are discussed. the bearing capacity characteristics of heat exchanger piles after heating operation is analyzed. It is shown that the values of c,φ of the clay are reduced with the rise of temperature,i. e.,strength of soil is reduced.During the heating operation,the ultimate bearing capacity of the pile is greatly improved,and the higher the temperature,the greater the ultimate bearing capacity of single pile is. The strength decrease of clay has little influence on the ultimate bearing capacity. The results can provide a theoretical basis for the design and calculation of bearing capacity of heat exchanger piles.