土工布包裹对粗粒料三轴试验的影响研究

Triaxial test analysis of influences of geotextile on coarse-grained soil

粗粒料三轴试验中,常使用在试样周围包裹土工布的方法防止橡皮膜被刺破。借助中型三轴仪,分别对粗粒料进行包裹土工布与未包裹土工布的常规三轴固结排水剪切试验,研究了土工布对试样强度和变形特性的影响。试验结果表明:对于相同的围压,包裹土工布试样的峰值强度(σ1-σ3)f都比未包裹土工布的要大;低围压下,包裹土工布使试样强度提高很大,但随围压的增加,强度提高的幅值呈幂函数形式减小。对于线性强度指标,包裹土工布试样的黏聚力c是未包裹土工布试样的1. 8倍,而内摩擦角φ则减小了1. 8°。对于非线性强度指标,包裹土工布试样的φ0是未包裹土工布试样的1. 07倍,Δφ增加了5. 5°。在相同围压下,包裹土工布试样的体积应变和侧向应变都比未包裹土工布试样的大;包裹土工布与未包裹土工布试样的体积应变差和侧向应变差受围压变化的影响较小。

In the triaxial tests of coarse-grained soil, the geotextile is often used to wrap the specimen used to prevent the rubber membrane from being punctured. This method is widely applied to the practical works. Therefore, the testing analysis of the influences of the geotextile on the strength and deformation behaviors of the coarse-grained soil is carried out in this study. The coarse-grained soil wrapped by the geotextile and that without the geotextile are subjected to a series of drained triaxial compression tests using medium size specimens. The experimental analysis results show that the strength （ 0-1-0-3 ） f of the specimens wrapped by the geotextile is larger than that of the normal specimens without the geotextile under the same confining pressure, and the increment ratio is decreasing with the increase of the confining pressure. In addition, the relationships between the increment ratio and the confining pressure can be expressed by a power function. The linear strength index of the specimens wrapped by the geotextile, cohesionc, is 1.8 times than that of the normal specimens without the geotextile, and the internal friction angle φ is reduced by 1.8°. The nonlinear strength index of the specimens wrapped by the geotextile, φ0, is 1.07 times that of the normal specimens without the geotextile, while △φ is increased by 5.5°. The volumetric strain and the lateral strain of the specimens wrapped by the geotextile are larger than those of the normal specimens without the geotextile under the same confining pressure. The volumetric strain difference and the lateral strain difference of the specimens wrapped by the geotextile and the normal specimens without the geotextile are less affected by the confining pressure, which is a constant independent of the confining pressure.