纤维煤矸石改良膨胀土强度特性及邓肯-张模型参数

Strength Characteristics and Duncan-Chang Model Parameters of Expansive Soil Improved by Fiber Coal Gangue

为了改善膨胀土胀缩性能和强度特性,以煤矸石和纤维为改良材料,研究聚丙烯纤维和煤矸石对膨胀土的强度影响及本构关系。将不同质量比的煤矸石掺入膨胀土中进行无荷载膨胀率试验和收缩试验,将不同质量比的聚丙烯纤维掺入煤矸石改良膨胀土中进行三轴固结排水试验,分析其应力-应变关系,获取改良土邓肯-张模型参数,并采用MATLAB软件对模型参数进行分析。结果表明:煤矸石可有效抑制膨胀土的胀缩性,煤矸石掺量为40%时,对膨胀土胀缩性的改良效果最好;在此煤矸石掺量下,随着纤维掺量的增加,改良膨胀土的抗剪强度呈先增大后减少的趋势,纤维掺量为0.3%时,改良膨胀土的强度最高,并且当纤维掺量相同时,周围压力越高,纤维对改良土强度提高越显著;采用MATLAB软件得到纤维掺量和围压对模型参数a、b的拟合函数,代入到邓肯-张模型中,模型能较好地模拟试验获得的应力-应变数据。

In order to improve the expansion and contraction properties and strength characteristics of expansive soil,the effects of polypropylene fiber and coal gangue on the strength and constitutive relationship of the expansive soil were studied by using coal gangue and fiber as the improved materials.Coal gangue with different mass ratios was incorporated into the expansive soil for load-free expansion rate test and shrinkage test,and polypropylene fibers with different mass ratios were incorporated into the improved expansive soil of the coal gangue for triaxial consolidation and drainage test,the stress-strain relationship was analyzed,the parameters of the improved soil Duncan-Chang model were obtained,and the model parameters were analyzed by MATLAB software.The results show that coal gangue can effectively inhibit the expansion and contraction of the expansive soil,and when the amount of coal gangue is 40%,the improvement effect on the expansion and contraction of the expansive soil is the best.In this coal gangue content,with the increase of fiber content,the shear strength of the improved expansive soil increases first and then decreases.When the fiber content is 0.3%,the strength of the improved expansive soil is the highest,and when the fiber content is the same,the higher the surrounding pressure,the fiber can more effectively improve the strength of the improved soil.The fitting function of the fiber content and confining pressure pair parameters a and b obtained by MATLAB software is substituted into the Duncan-Chang model,and the model can better simulate the stress-strain data obtained by the test.