土工格室条带拉伸力学特性试验研究

Experimental investigations on tensile mechanical properties of geocell strips

土工格室作为一种新型三维立体加筋加固岩土材料,通过约束土体侧向变形继而提升结构承载力,减小变形。目前国内外对土工格室的研究主要集中在工程应用和加筋机理上,对土工格室材料特别是条带本身的拉伸力学特性研究相对较少。通过对高密度聚乙烯HDPE,聚丙烯PP和聚酯PET 3种原料制成的土工格室条带进行单轴拉伸试验,研究了试样形状(Ⅰ型-哑铃形、Ⅱ型-矩形)及试样尺寸(Ⅱ型-矩形、Ⅲ型-矩形)对土工格室条带强度和变形特性的影响,并对土工格室条带的断裂处进行了微观分析。结果表明,HDPE、PP、PET 3种土工格室条带的伸长率均对试样形状敏感,Ⅰ型-哑铃形试样伸长率小于Ⅱ型-矩形试样。HDPE土工格室条带的抗拉强度受试样形状、尺寸影响均较小。PP、PET土工格室条带的抗拉强度受试样形状影响较大,Ⅰ型-哑铃形抗拉强度小于Ⅱ型-矩形试样。HDPE土工格室条带断裂面较粗糙,有明显的塑性屈服变形。PP土工格室条带断裂面微纤束排列整齐,小微纤杂乱分布。PET土工格室条带断裂面较平滑。试验结果可为土工格室加筋加固机理研究提供参考。

The geocell is a new type of three-dimensional reinforced geotechnical material to restrain the lateral deformation of the soil to enhance the bearing capacity of structure and reduce its deformation. At present, the worldwide investigations on geocells are mainly focused on their engineering applications and reinforcement mechanism, while limited investigations are conducted on themselves, especially the tensile mechanical properties of the strips. The uniaxial tensile tests are conducted on the geocell strips made from high-density polyethylene(HDPE), polypropylene(PP) and polyester(PET). The effects of the shapes(Type I-dumbbell, Type II-rectangular) and sizes(Type II-rectangular, Type III-rectangular) of the specimens on the strength and deformation characteristics of geocell strips are studied, and the micro-analysis on the failure geocell strips is performed. It is determined that the elongation rates of the HDPE, PP and PET geocell strips are sensitive to the specimen shape. The elongation of Type I-dumbbell is smaller than that of Type II-rectangular. The shape and size of the specimens have some effects on the strength of the HDPE geocell strips. The strengths of PP and PET geocell strips are greatly affected by the specimen shape. The tensile strength of Type I-dumbbell is smaller than that of Type II-rectangular. The fractured surface of HDPE geocell has rough surface and obvious plastic yield deformation. The microfibril bundles on the fractured surface of the PP geocell are neatly arranged, and the microfibrils are randomly distributed. The fractured surface of PET geocell is smooth. The test results can provide reference for the study on reinforcement mechanism of the geocells.