权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

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20世纪80年代末S以来，土工织物加筋土法已广泛应用于日本铁路、公路的挡土墙、桥台等重要结构，其性价比优于传统的桩基钢筋混凝土(RC)结构。然而，为了使新方法得到更广泛的推广，有必要使加筋土结构在竖向压缩荷载下具有更大的刚度，并使其具有较高的稳定性和不显著低于RC结构的刚度。为此，发明了一种新的方法，称为预加载和预应力(PLPS)加筋土法。该方法以级配砾石为回填材料，对压实良好的土工织物加筋土路堤，利用多根拉杆对其加筋区进行竖向压缩。首先，将加固后的回填土按设计荷载的两倍左右进行预加载，使其在…下变形。更多的是变态。其次，将回填土卸载至与设计荷载大致相同的荷载水平。最后，将拉杆的顶端固定在回填土顶部的反力块上，使体系处于预应力状态。在此基础上，对采用PLPS加筋土法施工的模型路堤和原型铁路桥墩进行了荷载试验和详细测试。此外，还对填土材料(级配较好的砾石)进行了大型三轴压缩试验。在此基础上，探讨了PLPS加筋的可行性和机理，提出了PLPS加筋土结构变形的定量预测方法和设计方法。主要结论如下：a)由于加固了土体，因此可以采用大覆盖层。预压使土体变得近乎弹性和僵硬。此外，土体上的预压在水平布置的土工织物中引入了拉伸预应力，将回填土限制在水平方向上。b)高的垂直预应力使回填土具有更高的垂直和压应力条件，因此土体相对于垂直荷载表现出更高的刚度。c)当施加低于预载荷级的竖向荷载时，在预压过程中发生的Sufficinet蠕变变形导致蠕变变形的抑制和拉杆张力的降低。d)当垂直压缩荷载施加在结构顶部时，作用在回填土上的荷载增加量减少，因为拉杆张力因回填土的压缩而减少。较少