考虑养护温度的水泥土搅拌桩强度模型探讨

室内水泥土标准试验与现场水泥土搅拌桩在养护温度和成桩工艺方面存在较大差异,导致室内水泥土抗压强度难以合理反映现场水泥土搅拌桩抗压强度。为此引入等效龄期理论和调整系数分别反映不同温度历程和成桩工艺对现场水泥土搅拌桩抗压强度的影响,从而建立考虑养护温度的水泥土搅拌桩强度模型。首先在室内开展了5、20、40 ℃ 3种不同养护温度的水泥土抗压强度试验;然后采用最小二乘法估计了水泥土活化能,并采用优化算法辨识了水泥土抗压强度模型参数;最后基于典型水闸工程地基温度和桩身强度检测值,识别了该模型的调整系数。分析表明,同龄期水泥土抗压强度随养护温度的增加而增加;成桩工艺差异对水泥土强度影响较大;新模型能较好地反映水泥土搅拌桩强度的发展规律。

Discussion on Strength Model of Cement-Soil Mixing Pile Considering Curing Temperature

In-situ cement-soil mixing pile differs markedly from laboratory cement-soil standard test in terms of curing temperature and pile forming technology, making it difficult to reasonably reflect the compressive strength of cement-soil mixing pile on site. In view of this, we established a strength model for cement-soil mixing pile which considers the curing temperature by introducing the equivalent age theory and the adjustment coefficient to reflect respectively the influences of temperature history and pile forming technology. First of all we conducted compressive strength test on cement-soil under three different curing temperatures (5 °C, 20 °C, and 40 °C). We further estimated the activation energy of cement-soil by the least square method and identified the parameters of the compressive strength model using the optimization algorithm. Finally, we obtained the adjustment coefficient of the model based on the foundation temperature and the detected strength of the cement-soil mixing pile in a typical sluice project. Results implied that the compressive strength of cement-soil at the same age augmented with the rising of curing temperature. Pile forming technology has remarkable impact on the strength of cement-soil. The present model well reflects the development law of the strength of cement-soil mixing piles.