基于正交设计的永久路面半刚性基层弯拉强度试验研究

EXPERIMENTAL STUDY ON FLEXURAL TENSILE STRENGTH OF SEMI-RIGID BASE OF PERMANENT PAVEMENT BASED ON ORTHOGONAL DESIGN

选取水泥剂量、含水量、压实度、19.0 mm、9.5 mm和4.75 mm筛孔通过率6个因素3个水平进行了正交试验,研究了各因素对水泥稳定碎石半刚性基层弯拉强度的影响,通过极差分析方法得出了弯拉强度的敏感性影响因素,分析了敏感性影响因素对弯拉强度的影响规律,并以河北京德高速半刚性基层永久性路面为依托,基于施工现场统计数据波动范围建立了施工参数变异水平与90 d弯拉强度的响应面模型。结果表明:水泥剂量均为水泥稳定碎石基层各龄期弯拉强度的最显著影响因素,压实度和4.75 mm筛孔通过率的影响较为显著,建议施工过程中应重点控制此3项指标;基层混合料的弯拉强度均随水泥剂量的增加而增大,随着龄期的增长,水泥剂量的变化对弯拉强度的影响程度呈先增大后减小的趋势,弯拉强度在28 d、60 d随水泥剂量变异的程度较显著;基层混合料的弯拉强度随压实度的增加而增大,各龄期弯拉强度的增加值随压实度的增长速率几乎相近;水泥剂量和压实度参数变异性对90 d弯拉强度影响程度排序为水泥剂量均值>压实度均值>水泥剂量变异系数>压实度变异系数,90 d龄期弯拉强度与敏感性影响因素及变异性的响应面回归模型的F值为155.79,P值小于0.0001,精度较高,可用于实际工程弯拉强度的预测和控制。

Six factors and three levels of cement dosage,water content,compactness,19.0 mm,9.5 mm and 4.75 mm sieve passing rate are selected for orthogonal test.The effects of various factors on the flexural tensile strength of cement stabilized macadam semi-rigid base are studied.The sensitive influencing factors of flexural tensile strength are obtained by range analysis method,and the influence law of sensitive influencing factors on flexural tensile strength is analyzed.Based on the semi-rigid base permanent pavement of Hebei Jingde Expressway and the fluctuation range of construction site statistical data,the response surface model of construction parameter variation level and unconfined compressive strength is established.The results show that the cement dosage is the most significant factor affecting the flexural tensile strength of cement stabilized macadam base at each age,and the compactness and the passing rate of 4.75 mm sieve are more significant.It is suggested that these three indexes should be controlled in the construction process.The flexural tensile strength of base course mixture increases with the increase of cement dose.With the increase of age,the influence of cement dose on flexural tensile strength first increases and then decreases.The variation of flexural tensile strength with cement dose is more significant at 28 d and 60 d.The tensile strength of the mixture increases with the increase of the bending strength of the compacted base.The order of the influence of the variation level of construction parameters on the 90d flexural tensile strength is as follows:mean value of cement dosage>mean value of compactness>coefficient of variation of cement dosage>coefficient of variation of compactness.The F value of the response surface regression model of 90 d flexural tensile strength and sensitivity factors variability is 155.79,and the P value is less than 0.0001.It has high accuracy and can be used for the prediction and control of flexural tensile strength in practical engineering.