锚杆加固散粒体的作用机制研究

STUDY OF ANCHORAGE MECHANISM OF GRANULAR MIXTURE

采用细观数值模拟的方法研究岩土工程中散粒体锚杆加固的作用机制,基于随机模拟技术建立加锚散粒体的三维随机颗粒模型,采用颗粒形状系数控制颗粒表面的不均匀起伏程度,基于修正的增广Lagrangian算法的非线性接触算法模拟颗粒之间、颗粒与锚固体、颗粒与承托结构的相互接触,颗粒的物理力学性质服从Weibull概率分布,采用细观损伤软化模型描述颗粒的变形和破碎。分别建立散粒体和加锚散粒体的三轴数字试样,采用位移加载来进行不同围压下的常规三轴剪切试验,研究不同加锚密度对散粒体工程力学特性的影响。数值模拟结果表明:锚杆加固的作用机制为锚固体与颗粒紧密接触、相互咬合形成摩擦阻力,承托结构形成对颗粒体的径向助力,锚杆与其附近的颗粒形成锚固区;锚杆加固能显著提高散粒体的抗剪强度和整体性,峰值主应力差提高37.8%～88.8%,初始模量提高37.4%～93.2%,内摩擦角提高13.3%～24.2%。

The mesoscopic numerical simulation method is employed to study the anchorage mechanism of granular mixture in geotechnical engineering.3D random distribution particle model of granular mixture is built based on random simulation technique;the form factor is used to control the surface irregularity of the granules.In addition,nonlinear contact algorithm is presented based on modified augmented Lagrangian algorithm and is employed to simulate the interaction between granule and rockbolt.The mechanical properties of granule obey Weibull probability distribution;mesoscopic damage softening model is employed to describe granule deformation and breakage.The numerical models for triaxial shear test of granular mixture and anchored granular mixture are built;triaxial shear test is carried out based on displacement loading.The numerical simulation results show the anchorage mechanism,i.e.anchorage body intimately contacts the rock particles to produce the frictional resistance,and supporting structure forms the radial resistance the anchors and their adjacent rock granules form the anchorage zone.The numerical calculation results show that anchorage can significantly increase the shear strength and integrity of granular mixture.The peak principal stress difference can increase by 37.8%-88.8%,the initial modulus can increase by 37.4%-93.2%,and the internal friction angle can increase by 13.3%-24.2%.