柔性加筋土复合体强度及变形特性试验研究

发布时间：2018-03-30 20:36

本文选题：柔性加筋土复合体　切入点：室内试验　出处：《武汉理工大学》2014年硕士论文

【摘要】：有研究表明，土工合成材料加筋的高压实度粒料土，如果加筋层间距足够小，则受压时筋-土界面几乎不产生相对位移，可看成是一种复合材料。这里将具备此种性质的加筋土称为柔性加筋土复合体，由其形成的结构物称为加筋土复合体结构。一些试验表明，加筋土复合体结构具有承载力高，变形小，自稳性好，抗震性能优良，工程成本低等优良工程特性，所以适合于用来修建具有高抗震性能的柔性桥台、挡土墙、加筋陡坡等支承结构，具有广阔的应用前景。但相关的研究还很少，以致在加筋土复合体的形成机理、形成条件、力学特性等基本理论问题还很不清楚，需要进行系统的研究，以便将来在工程实践中能得到推广应用。有鉴于此，本文采用试验与数值分析相结合的手段对柔性加筋土复合体的力学性能和变形特性进行了初步研究。分别采用室内无侧限抗压强度试验和数值模拟试验，探讨了加筋材料种类、加筋层间距、土的类别和压实度等对柔性加筋土复合体的抗压强度、变形特性的影响规律。根据试验结果，利用FLAC3D软件建立了数值分析模型，，对加筋土路堤边坡稳定性及其影响因素进行了分析。论文得到以下主要结论：（1）加筋土复合体抗压强度和抗压刚度都随加筋层间距的减小或者压实度的提高而增大。（2）柔性加筋土复合体的应力-应变形态受加筋层间距的影响较大，随加筋层间距的逐渐减小，其应力-应变曲线由应变软化型逐渐向应变硬化型转变。这说明在一定条件下，当加筋层间距小于某一临界值时，加筋土的变形特性会发生质的变化。该临界值也许就是普通加筋土过渡到加筋土复合体的分界点，因此研究该临界值的影响因素和影响规律，进而研究该临界值的确定方法是值得进一步研究的重要课题。（3）基于上述观点，作者对大尺寸土工格栅加筋粒料土试件进行了无侧限压缩数值模拟试验，其结果表明，对于加筋层间距小到30cm的加筋土试件，当压缩量大于1.5cm后，其轴向压力随着压缩变形的增大呈直线增加，说明间距足够小时，加筋土表现出了类似于连续固体介质的复合材料特性。（4）与未加筋土边坡相比，加筋显著提高了陡边坡的稳定性且具有更大的安全储备，加筋土边坡的安全系数随着加筋层间距增大或者筋材长度减小而减小，同未加筋土边坡一样，填料特性对加筋土边坡稳定性有重要的影响。
[Abstract]:Some studies have shown that if the spacing of the reinforced layer is small enough, the interface between the reinforcement and the soil can hardly produce relative displacement when the geotextile is reinforced by the geotextile. The reinforced soil with this property is called flexible reinforced soil complex, and the structure formed by it is called reinforced soil complex structure. Some tests show that the reinforced soil complex structure has high bearing capacity. Small deformation, good self-stability, good seismic performance, low engineering cost and other excellent engineering characteristics, so it is suitable for building flexible abutment, retaining wall, reinforced steep slope and other supporting structures with high seismic performance. It has a broad application prospect, but the related research is still few, so the basic theoretical problems such as formation mechanism, forming conditions, mechanical properties of reinforced soil complex are not clear, so it is necessary to carry out systematic research. In order to be popularized and applied in engineering practice in the future. In this paper, the mechanical properties and deformation characteristics of flexible reinforced soil complex are studied by means of the combination of test and numerical analysis. The indoor unconfined compressive strength test and numerical simulation test are used respectively. The effects of the type of reinforced material, the spacing of stiffened layer, the type of soil and the compaction degree on the compressive strength and deformation characteristics of the flexible reinforced soil complex are discussed. Based on the test results, a numerical analysis model is established by using FLAC3D software. The stability of reinforced embankment slope and its influencing factors are analyzed. The main conclusions are as follows:. 1) the compressive strength and stiffness of the reinforced soil complex increase with the decrease of the reinforcement layer spacing or the increase of the compaction degree. (2) the stress-strain pattern of the flexible reinforced soil complex is greatly affected by the spacing of the reinforced layer, and the stress-strain curve changes from the strain softening type to the strain hardening type with the decreasing of the reinforced layer spacing, which indicates that under certain conditions, the stress-strain curve of the composite is changed gradually from the strain softening type to the strain hardening type. When the spacing of reinforced soil is less than a certain critical value, the deformation characteristics of reinforced soil will change qualitatively. This critical value may be the dividing point of the transition of common reinforced soil to reinforced soil complex, so the influencing factors and law of the critical value are studied. The method of determining the critical value is an important subject worthy of further study. (3) based on the above viewpoint, the numerical simulation tests of the large size geogrid reinforced granular soil specimens are carried out. The results show that for the reinforced soil specimens with small reinforced layer spacing as small as 30cm, when the compression amount is greater than 1.5cm, The axial pressure increases in a straight line with the increase of compression deformation, indicating that the reinforced soil exhibits a composite property similar to that of a continuous solid medium when the spacing is small enough. Compared with the unreinforced soil slope, the reinforced soil slope has significantly improved the stability of the steep slope and has a greater safety reserve. The safety factor of the reinforced soil slope decreases with the increase of the reinforcement layer spacing or the decrease of the reinforcement material length, just like the unreinforced soil slope. The characteristics of fillers have an important effect on the stability of reinforced soil slope.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U416.1

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