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防渗墙上接复合土工膜是围堰常用的防渗体系,联接部位的有效性是决定防渗成败的关键。以某围堰工程为原型开展离心模型试验,通过监测复合土工膜在堰体与防渗墙变形过程中的应变,揭示复合土工膜的受力性状和联接部位的破坏机理。结果表明:一定上覆荷载作用下,复合土工膜与堰体之间的摩阻力超过其所承受的拉伸力,导致预留伸缩节不能发挥作用;复合土工膜下部风化砂的固结变形使之与刚性防渗墙之间产生较大的差异沉降,以及防渗墙与上游堰体的水平脱离,此两种变形不协调均可导致与防渗墙联接的复合土工膜因受拉而破坏。基于此,提出了防渗墙与复合土工膜联接型式的改进方法,使联接部位的复合土工膜不承受拉应力,通过离心模型试验验证其合理性和可行性,为指导围堰防渗体系的设计和施工提供了可靠的试验依据。
Impervious wall connected composite geomembrane is commonly used in cofferdam seepage control system, the effectiveness of the joint is the key to determine impermeability. Taking a cofferdam project as a prototype, a centrifuge model test was carried out. By monitoring the strain of the composite geomembrane during the deformation of the weir and the impervious wall, the mechanical properties of the composite geomembrane and the failure mechanism of the joint were revealed. The results show that the frictional resistance between the composite geomembrane and the weir exceeds the tensile force that it is subjected to under the action of a certain overlying load, resulting in the failure to reserve the expansion joint. The consolidated deformation of the weathered sand at the lower part of the geomembrane And the rigid impervious wall between the larger differential settlement, and the horizontal cutoff wall and the upstream weir, these two deformations can lead to uncoordinated with the cutoff wall of the composite geomembrane tension caused by damage . Based on this, an improved method for the joint type of impermeable wall and composite geomembrane is put forward, which makes the composite geomembrane of joint part not to bear the tensile stress. The centrifugal model test verifies its rationality and feasibility. In order to guide the seepage control system of cofferdam, Design and construction provide a reliable basis for testing.