黄土古土壤工程力学性质机理研究

黄土古土壤区开展工程建设活动受其工程力学性质影响巨大。为揭示黄土古土壤工程力学性质,从银西铁路早胜一号隧道取得黄土古土壤试样,通过室内无侧限抗压强度试验、抗拉强度试验、直剪试验及无荷载膨胀率测试,研究其力学强度及参数,以期为黄土古土壤地区工程建设活动提供科学依据和研究参考。结果表明,早胜一号隧道1号斜井西安方向上、中、下3个台阶处,黄土古土壤试样的峰值抗压强度分别为5.09 MPa、4.98 MPa和4.28 MPa,抗拉强度分别为0.59MPa、0.57 MPa和0.56 MPa。通过采用Mohr-Coulomb准则进行拟合峰值抗剪强度与正应力的关系,从而获得黄土古土壤强度参数,内摩擦角分别为34.70°、36.14°和35.39°,粘聚力分别为67.93 kPa、68.74 kPa和65.59 kPa。上台阶处黄土古土壤膨胀率最大值可达5.78%,原状和重塑黄土古土壤的最大无荷载膨胀率随含水率的增加呈幂函数下降,整个含水率变化过程中,重塑黄土古土壤的最大无荷载膨胀率均比原状黄土古土壤的大。

Engineering construction activities in loess palaeosol area are greatly affected by its engineering mechanical properties.In order to reveal the engineering mechanical properties of loess palaeosol,the loess palaeosol samples were obtained from the Zaosheng tunnel No.1 of Yinchuan-Xi’an Railway.Through the indoor unconfined compressive strength test,tensile strength test,direct shear test and No load expansion rate test,to study its’mechanical strength and parameters,in order to provide scientific basis and research reference for engineering construction activities in the loess palaeosol area.The results show that,at the three steps above,in and below the Xi’an direction of the No.1 inclined shaft of Zhaosheng No.1 Tunnel,the peak compressive strength of loess palaeosol samples is 5.09 MPa,4.98 MPa and 4.28MPa,the tensile strength is 0.59 MPa,0.57 MPa and 0.56 MPa.By Mohr-Coulomb criterion to fit the relationship between peak shear strength and normal stress,so the strength parameters of loess paleosol can be obtained,the internal friction angles are 34.70°,36.14°and 35.39°,the cohesiveness are 67.93 kPa,68.74 kPa and 65.59 kPa.The maximum expansion rate of the loess palaeosol at the upper step was 5.78%,the maximum unloaded expansion rate of undisturbed and remolded loess palaeosols decreased as a power function with the increase of water content,during the whole process of moisture content change,the maximum unloaded expansion rate of remolded loess palaeosol is larger than that of original loess palaeosol.