冻融循环下黄泛区粉土动力特性评价

Evaluation of dynamic characteristics of silt in Yellow River Flood Field after freeze-thaw cycles

由温度、盐分和车辆交通荷载的耦合作用造成的路基土动力强度的丧失,使翻浆成为山东黄泛区公路的主要病害,其成因与该地区粉土的动力特性密切相关。为了分析这些耦合效应对粉土动力特性的影响,本研究进行了冻融循环试验、动三轴试验和超声波试验,设计了两种粉土(无盐粉土和3%盐粉土)。冻融循环试验和动三轴试验的结果表明,随着冻融循环次数的增加,动剪切强度和动模量降低,但阻尼比增大。另外,与无盐粉土相比,含盐量为3%的粉土的动剪切强度和动模量下降幅度更大,但阻尼比反而增大。在超声波试验中,冻土试件的超声波速度随冻融循环次数的增加而减小。根据超声波试验结果,提出了一种通过现场实测超声波数据来评价粉土损伤的初步模型,这为粉土公路的治理提供了理论依据。

Frothing is a main disease of highways in Yellow River Flood Field, due to the loss of dynamic strength of roadbed soils under the couple effects of temperature, salt, and vehicle traffic load. This is strongly linked to the dynamic characteristics of silt in this region. To analyze these couple effects on the dynamic characteristics of silt, a series of tests(i.e., freeze-thaw cycling tests, vibration triaxial tests and ultrasonic wave velocity tests) were conducted and two kinds of silt(i.e., salt-free and 3%-salt silt) were designed. The results indicate that the dynamic shear strength and dynamic modulus decrease with increasing freeze-thaw cycles, while the damping ratio simultaneously increases. Furthermore, compared to salt-free silt, the decrement of dynamic shear strength and dynamic modulus of silt with 3% salt is more significant, but the damping ratio of 3%-salt silt is larger. In ultrasonic wave velocity tests, ultrasonic wave velocity of frozen soil specimens decreases as the number of freeze-thaw cycles increases. Based on the results of ultrasonic wave velocity tests, a preliminary model is proposed to evaluate damage of silt through field measurement ultrasonic data. The study could provide a theoretical basis for the treatment of silty soil highway.