Development of prestressed geotextile-reinforced soil

预应力土工布加筋土的研制

基本信息

批准号：
07555150
负责人：
TATSUOKA Fumio
金额：
$ 4.61万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

Since late 1980's, geotextile-reinforced soil method has been widely used for important structures as reraining walls and bridge abutments for reilways or highways in Jpana, resulting from its cost-performance ratio superior to that of conventional method using reinforced concrete (RC) structures supported by pile foundations. To make the new method spread more widely, however, it is necessary to make reinforced soil structures much stiffer against vertical compressive load and to give them high stability and stiffness not significantly lower than those of RC structures. For that purpose, a new method called 'preloaded and prestressed (PLPS) reinforced soil method' was invented. In the method, a well compacted geotextile-reinforced soil embankment using well graded gravel as the backfill is vertically compressed on its reinforced area by using several tie rods. First, the reinforced backfill is preloaded at the load level about twice as large as that of the design load to be deformed b … More y creep. Second, the backfill is unloaded to the load level about the same as the design load. Finally the top ends of the tie rods are fixed to the reaction block on the top of the backfill to make the system in a prestressed condition. The structure is used as a bridge abutment or pier under that condition.In this study, loading tests and detailed measurements were performed on a full scale model embankment and a prototype railway bridge pier, which were constructed by the PLPS reinforced soil method. In addition, large scale triaxial compression teats were preformed on the fill materials (well graded gravels). The feasibility and mechanisms were examined based on the results, and the method for quantitative prediction of the deformation and the design method for PLPS reinforced soil structures were developed. The major conclusions are as follows.a) Large prcload can be applied because the soil is reinforced. The preloading makes the soil nearly elastic and stiff. In addition, preloading on the soil introduces tensile prestress in the geptextile arranged horizontally, which confines the backfill in the horizontal direction.b) High vettical prestress gives the backfill higher, vertical and compressive stress condition, therefore the soil shows higher stiffness against vertical load.c) Sufficinet creep deformation which occurs during preloading results in a suppression both of the creep deformation and the decrease in the tie rod tension when a vertical load lower than the preload level is applied.d) When vertical compressive load is applied on top of the structure, the amount of increase in the load which works on the backfill decrease because the tie rod tension decreases by compression of the backfill. Less

自1980年代末以来，土工布增强土壤法已被广泛用于重要结构，作为墙壁和桥梁基台，用于退休或JPANA的高速公路，这是由于其成本的性能比使用了浓缩的混凝土（RC）结构所支持的常规方法优于常规方法。但是，为了使新方法更广泛地扩散，有必要使增强的土壤结构在垂直压缩载荷上更加僵硬，并使其具有高稳定性和刚度不如RC结构的高稳定性和刚度。为此，发明了一种称为“预加载和预应力（PLP）增强土壤方法”的新方法。在该方法中，使用良好的重力良好的土工布增强的土壤路堤，因为通过使用几条拉杆，在其增强区域垂直压缩了回填充物。首先，在负载水平上预加载了增强的回填，大约是设计负载的两倍，该载荷要变形B…更蠕变。其次，将回填卸载到与设计负载相同的负载水平。最后，拉杆的顶端固定在回填顶部的反应块上，以使系统处于预应力状态。在该条件下，该结构用作桥梁基台或码头。在这项研究中，在完整的模型路堤和原型铁路桥码头上进行了加载测试和详细的测量，该测试是由PLPS增强土壤方法构建的。另外，大规模三轴压缩奶头在填充材料上预先形成（分级图）。根据结果检查了可行性和机制，并开发了定量预测变形的定量预测方法和PLPS增强土壤结构的设计方法。主要结论如下。预加载使土壤几乎弹性和僵硬。此外，在土壤上的预加载在水平排列的geppterxtile中引入拉伸预应力，这限制在水平方向上的回填。在拉杆张力中，当垂直载荷低于预加载水平时。较少的