重盐土在温度变化时的物理化学性质和力学性质

在降温过程中,重盐土的物理化学性质及力学性质发生重要变化:易溶盐向土体冷端迁移;土壤溶液中的硫酸钠呈水合芒硝析出,因而使土体积膨胀(即盐胀);盐胀使土的强度降低。盐胀率随降温速率、上覆荷载值、土的初始密度及土粒间的粘聚力的增大而降低,随土含水量的增大而提高。盐胀率峰值发生在特定的温度区间。在温度回升时,土体积并不明显回缩,这说明盐胀过程具有不可逆性。在温度反复升降过程中,盐胀量逐步累增,土的无侧限抗压强度也逐渐降低。     

A NEW MODEL OF FROST HEAVE PREDICTION FOR CLAYEY SOILS

After analysing the results of systematic experimental research on frost susceptibility tests, a new frost heave prediction model, including the heave ratio η and rate R, is first proposed in this paper. Six main factors influencing frost heave are considered: initial water content W, initial dry unit weight γd, frost penetration rate Vf, groundwater level Hw, plasticity index Ip and ion content S. The model could be expressed by: η= B0WB1γBd2VB31·exp(B4Hw)exp(B5Ip)exp(B6S) and R = B'0WB'1γB'2dexp(B'3Hw)exp(B'4Ip)exp(B'5S) with a good reliability, where B0 to B6 and B'0 to B'5 are the characteristic constants of clayey soils. The effect of each factor on frost susceptibility of soils is discussed also.     

粘性土冻胀预报新模型

通过系统的多因素之土冻胀敏感性试验研究,本文首次提出同时考虑初始含水量W、初始干容重γ_d、冻结速率V_f、地下水位埋深H_w塑性指数I_p及盐离子含量S等综合作用,且反映粘性土冻胀特性的冻胀率η及冻胀速率R之预报模型:η=B_0W~(B_1)γ_d~(B_2)V_f~(B_3)exp(B_4Hw)exp(B_5I_p)exp(B_6S)及R=B'_0W~(B'_1)γ_d~(B'_2)exp(B'_3Hw)exp(B'_4I_p)exp(B'_5S),具有较高的可信度,还分析了诸因素对土冻胀敏感性的影响.