裂隙对红黏土抗剪强度衰减影响试验研究

Experimental study on the influence of cracks to shear strength attenuation of red clay

为了研究松旺—铁山港东岸高速公路路基红黏土裂隙对其抗剪强度的影响,通过室内干湿循环试验,借助图片处理技术和数学模型统计红黏土表面裂隙分形维数以及裂隙率,将每次干湿循环后的试样进行直剪试验,并对红黏土裂隙开展过程中基质吸力等变量进行分析,建立力学模型,得到其开裂的临界条件以及判别标准。研究结果表明:人工湿化试样的抗剪强度随干湿循环次数的增加,均呈现先缓慢增加后快速减小的规律,而真空饱和试样抗剪强度的变化规律则稍有不同;红黏土抗剪强度与裂隙率、分形维数都存在较好的相关性,其可以作为判别裂隙对红黏土抗剪强度影响的指标。

In order to study the influence of the cracks of red clay on the shear strength of the roadbed for Songwang-Tieshan port east bank expressway, through the indoor dry-wet cycling tests, the fractal dimension and the crack rate of the surface cracks of the red clay are counted by using the picture processing technique and mathematical model, the samples after each dry-wet cycling are directly sheared and the matrix suction and other variables during the development of red clay cracks are analyzed. The mechanical model is established and the critical condition and criteria for cracking are obtained. The study results show that the shear strength of the manually wetted samples increases slowly and then decreases rapidly with the increase of wet and dry cycles, while the shear strength of the vacuum saturated samples varies slightly. The shear strength of red clay is well correlated with the crack rate and fractal dimension, which can be used as the index to judge the crack influence on the shear strength of red clay.