基于ANSYS的缩颈灌注桩内植热源温度场特征研究

Temperature field characteristics of build-in heat source in necked cast-in-place pile based on ANSYS

提出缩颈灌注桩内植热源缺陷检测方法,对温度荷载作用下桩基础内植热源的温度场进行数值模拟,对比完整桩与缩颈桩的温度场分布规律,分析缩颈部位的缺陷特征。结果表明:桩体在温度荷载作用下,沿桩深方向缺陷部位的温度突变,缩颈程度越大温升越高,缩颈为50 mm和100 mm时,温差递增较为明显,当缩颈超过200 mm后温差递增趋势减弱,依据相应规范可判定该类桩已属于四类桩;结合温度突变起点与终点之间的距离可判定缩颈长度,对比桩身完整部分的温度变化曲线可判定缩颈程度;通过适当增加加热功率,可缩短缺陷判别时间,增加判定准确性。以上研究结果验证了所提方法的可行性,可为今后桩基完整性检测试验确定缺陷位置、缺陷类型及缺陷程度提供理论依据。

The detection method of heat source defect in necked cast-in-place pile is proposed.The temperature field of build-in heat source planted in pile foundation under temperature load is simulated numerically.The temperature field distribution law of complete pile and necked pile was compared,and the defect characteristics of necking part were analyzed.The results show that the temperature mutated along the defect position along the pile depth direction under the effect of temperature load.The greater the degree of necking,the higher the temperature rise.When the necking shrinkage was 50 mm and 100 mm,the temperature difference increased more obviously.When the necking shrinkage exceeded 200 mm,the increasing trend of temperature difference was weakened.It can be judged that this kind of pile belongs to the forth level according to the corresponding specifications.The necking length can be determined by combining the distance between the starting point and the end point of temperature mutation,and the degree of necking can be determined by comparing the temperature change curve of the complete part of the pile body.The time of defect identification can be shortened and the accuracy of judgment can be increased by properly increasing the heating power.The above research results verify the feasibility of the proposed method,which can provide a theoretical basis for the future pile integrity test to determine the location,type and degree of defects.