P5含量对砾类土强度与变形特性影响的试验研究

为了研究粗粒含量对砾类土的强度与变形特性的影响,本文对5种不同粗粒含量的强风化灰岩土石混合体开展了室内大型直剪试验与数值模拟研究,并获取相关的强度与变形参数。室内试验结果表明:随粗粒含量增加,抗剪强度参数先增大后减小,粗粒含量70%时试样内摩擦角达到最大,黏聚力变化无明显规律。对实验数据进行统计分析表明,用径径比可以很好地体现试样级配、粒径大小、含量、试样尺寸的关系,最终得到抗剪强度与径径比关系的经验公式,可以初步预测粗粒土的抗剪强度。数值模拟结果表明:使用Clump"聚粒"模型模拟砾石能较好地拟合剪应力与剪位移曲线;剪切过程中剪切带附近颗粒运动表现为上凸的弧线,这个现象持续至剪切结束;力链表现为倾斜的珊瑚状,随剪切进行力链不断发展增强,至剪切完成力链稍有衰减。

Experimental study on influence of coarse grain content on strength and deformation characteristics of gravel soil

In order to study the influence of coarse grain content on the strength and deformation characteristics of the gravel soil， a large scale direct shear test and numerical simulation of 5 highly weathered limestone soil-rock mixtures with different coarse grain content are carried out in this paper，and the relevant strength and deformation parameters are obtained． The results of laboratory tests show that the shear strength parameters first increase and then decrease with the rise of coarse grain content． When the coarse grain content is 70% ，the internal friction angle of the sample reaches the maximum，and there is no obvious rule of cohesion change． The statistical analysis of the experimental data shows that the relationship between the grading，particle size and content，sample size can be well reflected by the diameter ratio，and the empirical formula of the relationship between the shear strength and the diameter ratio can be obtained，and the shear strength of coarse grained soil can be preliminarily predicted． The results of numerical simulation show that the shear stress and shear displacement curves can be well fitted by using Clump“aggregate”model to simulate gravel． In the process of shear，the movement of particles near the shear zone appears as an arc of convex，which continues until the end of shear． The force chain is inclined and coral-like． It develops and strengthens with shear，and then decreases slightly after shear．