气泡轻质土在山区公路拓宽应用中的力学特性研究

发布时间：2018-01-18 02:02

本文关键词：气泡轻质土在山区公路拓宽应用中的力学特性研究　出处：《西南科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：气泡轻质土是一种新型路基填土材料,具有高强轻质、凝结自立、施工便捷等特点,可用于桥头搭接、旧路拓宽、结构减载等多种工况。本文针对气泡轻质土路基在实际应用过程中的力学特性,通过强度试验、室内模型试验、并结合数值模拟分析,研究气泡轻质土在拓宽路基应用中的基本力学性能、荷载作用下的受力机理以及变形破坏特征等,得到气泡轻质土添加原料土(砂土)后的强度变化规律,气泡轻质土的三轴力学特性以及气泡轻质土路基在荷载作用下路基内部的应力应变规律,主要研究成果如下:(1)当原料土掺量小于32%时,气泡轻质土的抗压强度随原料土掺量的增加呈线性降低;当掺量超过32%时,其影响显著,此时气泡轻质土孔隙率明显增大。(2)气泡轻质土在三轴压缩过程中表现出较为明显的脆性破坏特征,这与普通路基填料差异较大。但在围压较大的情况下,轻质土的应力-应变关系接近软化型。(3)气泡轻质土路基在受载-破坏过程中,当荷载达到175kPa后,中层左侧轻质土路基内部最先发生局部破坏;随着荷载增大,且由于老路基沉降变形与轻质土路基局部破坏变形的共同作用,新老路基交接处产生裂缝,并逐渐发展扩大,直至路基整体失稳;该气泡轻质土路基受载-破坏模式是一个由内而外的从弹性变形到塑性屈服,最终发生弯剪破坏的过程,即先局部破坏再整体失稳的过程。
[Abstract]:Bubble lightweight soil is a new type of subgrade filling material, with the characteristics of high strength, light weight, self-supporting condensation, convenient construction, can be used for bridge lap, old road widening. According to the mechanical characteristics of bubble light soil subgrade in practical application, the strength test, indoor model test and numerical simulation analysis are used in this paper. The basic mechanical properties of bubble lightweight soil in the application of widening roadbed, the stress mechanism under load and the characteristics of deformation and failure are studied, and the change rule of strength of bubble light soil after adding raw soil (sandy soil) is obtained. The triaxial mechanical properties of bubble lightweight soil and the stress-strain law of bubble lightweight soil subgrade under load, the main research results are as follows: 1) when the amount of raw material soil is less than 32wt%. The compressive strength of bubble light soil decreases linearly with the increase of the content of raw material soil. When the content is over 32, the effect is obvious, and the porosity of bubble light soil is obviously increased. 2) the bubble light soil shows obvious brittle failure characteristics during triaxial compression. However, the stress-strain relationship of light soil is close to that of softening type. (3) in the process of load-failure of light soil subgrade, it is different from that of ordinary subgrade fillers, but in the case of large confining pressure, the stress-strain relationship of light soil is close to that of softening type. When the load reaches 175 KPA, the first local failure occurs in the left light soil subgrade. With the increase of load and the joint action of settlement deformation of old subgrade and local failure deformation of lightweight soil subgrade, cracks appear at the junction of new and old roadbed, and gradually develop and expand until the whole subgrade is unstable. The load-failure mode of bubble lightweight soil subgrade is a process from elastic deformation to plastic yield, and finally to bending and shear failure, that is, first local failure and then whole instability.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U414

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