圈围工程中高强有纺土工布加筋垫层变形试验研究

应用大刚度、长标距、大量程的SDW-100型位移传感器，采用500 kN/m高强有纺土工布进行室内试验和现场试验，研究高强土工布加筋垫层的变形情况。室内拉伸试验成果表明，位移传感器在每级加荷情形下的变形量与试验机上显示变形量具有较好的一致性，说明该类型传感器用于现场加筋高强土工布的变形测试是适用的，并因此得到高强有纺土工布的变形模量为8314.4 kN/m。现场试验表明，(1) 大堤底部的土工布位移曲线基本表现为盆形，中轴线下的土工布位移量最大；(2) 大堤下部土工布的位移量大小与外棱体的位移方向明显相关；(3) 现场试验中高强土工布的最大实测变形率为11.9%，按室内试验得到的变形模量计算出该计算高强有纺土工布的应力值为837.40 kN/m，表明按照现场实际加荷速率设计的高强有纺土工布强度值偏小；(4) 施工间歇期高强土工布的应力会出现重分布现象，具体表现为大堤轴线下变形量明显减小，现场实测成果与Plaxis有限元计算成果规律性吻合情况较好，试验成果符合一般规律；(5) 土工布的变形率与围堤上部现场施工加荷的速率关系很大，现场施工时设计单位应当提出一个加荷速率控制值；(6) 当高强有纺土工布的强度一定时，土工布的伸长率相对较大有利于快速加荷施工。

Experimental study of deformations of reinforced cushion by high-strength woven geotextile in closing levee

By using the data acquired from laboratory and field monitoring program, this study assessed the displacements of high-strength geotextile used as basal reinforcement of a closing levee. The displacements of the geotextile were monitored by high stiffness, large gauge length and measuring range SDW-100 displacement transducers with 500 kN/m high-strength woven geotextile .The transducers were first calibrated in a multi-function test machine. The tensile test of the geotextile yielded a tensile stiffness of 8314.4 kN/m. The field monitoring data indicate that: (1) The displacements of the geotextile at the base of the closing levee showing a concave shape and maximum displacement occurred along the center line. (2) The displacements of the geotextiles is explicitly influenced by the movement of the attached toe-berms. (3) The measured maximum strain is 11.9% which is equivalent to 837.40 kN/m in tension. The high strain indicates that the geotextile with higher tensile stiffness should be used. (4) The stress redistribution between the stages of the construction is observed. This phenomenon is further verified by numerical simulation using Plaxis. (5) The strain of the geotextile is a function of the closing levee backfilling rate. An appropriate backfilling rate should be selected to limit the strain in geotextile. (6) With the same tensile strength, the larger elongation can accommodate faster construction.