Moraine,as a coarse-grained transitional geomaterial between soil and rock,exhibits a direct theoretical linkage between its mesoscopic characteristics and macroscopic strength behavior.However,a well-established quan...Moraine,as a coarse-grained transitional geomaterial between soil and rock,exhibits a direct theoretical linkage between its mesoscopic characteristics and macroscopic strength behavior.However,a well-established quantitative model describing this relationship remains lacking.Moreover,existing methods for estimating surrounding rock pressure predominantly assume homogeneous continuous media and fail to systematically capture the quantitative link between meso-scale mechanical behavior and macro-scale pressure responses.To address these gaps,this study develops a mesoscopic interlocking mechanism for moraine based on granular mechanics theory,elucidating the controlling influence of the mesoscopic internal friction angle on macroscopic strength.By incorporating the arching effect at the meso-scale and the influence of relative particle size on arch height,the equilibrium arch axis equation for surrounding rock is refined within the framework of Protodyakonov’s theory.A novel formula for estimating moraine surrounding rock pressure,grounded in the meso–macro strength relationship,is proposed and validated through its application to a railway tunnel.The results indicate that:(1)The internal friction angle significantly affects the macroscopic strength of moraine,with higher values corresponding to greater strength.(2)Pressures calculated using the proposed meso–macro method are slightly higher than those derived from conventional approaches,reflecting the intrinsic coupling between mesoscopic features and macroscopic strength in loose moraine.(3)With increasing tunnel span,the growth rate of surrounding rock pressure based on the meso–macro relationship is markedly higher than that predicted by traditional methods,consistent with the frequent sudden collapse observed in large-span moraine tunnels.(4)The sensitivity of surrounding rock pressure to the internal friction angle increases with both the friction angle and tunnel span.This study provides a theoretical foundation and a novel calculation framework that explicitly quantifies the influence of meso-structural interlocking on the macro-mechanical behavior of moraine surrounding rock,thereby offering a more accurate basis for engineering design.展开更多
基金supported by the National Natural Science Foundation of China(Grant Number 12262018)Gansu Province Joint Research Fund Program(24JRRA850).
文摘Moraine,as a coarse-grained transitional geomaterial between soil and rock,exhibits a direct theoretical linkage between its mesoscopic characteristics and macroscopic strength behavior.However,a well-established quantitative model describing this relationship remains lacking.Moreover,existing methods for estimating surrounding rock pressure predominantly assume homogeneous continuous media and fail to systematically capture the quantitative link between meso-scale mechanical behavior and macro-scale pressure responses.To address these gaps,this study develops a mesoscopic interlocking mechanism for moraine based on granular mechanics theory,elucidating the controlling influence of the mesoscopic internal friction angle on macroscopic strength.By incorporating the arching effect at the meso-scale and the influence of relative particle size on arch height,the equilibrium arch axis equation for surrounding rock is refined within the framework of Protodyakonov’s theory.A novel formula for estimating moraine surrounding rock pressure,grounded in the meso–macro strength relationship,is proposed and validated through its application to a railway tunnel.The results indicate that:(1)The internal friction angle significantly affects the macroscopic strength of moraine,with higher values corresponding to greater strength.(2)Pressures calculated using the proposed meso–macro method are slightly higher than those derived from conventional approaches,reflecting the intrinsic coupling between mesoscopic features and macroscopic strength in loose moraine.(3)With increasing tunnel span,the growth rate of surrounding rock pressure based on the meso–macro relationship is markedly higher than that predicted by traditional methods,consistent with the frequent sudden collapse observed in large-span moraine tunnels.(4)The sensitivity of surrounding rock pressure to the internal friction angle increases with both the friction angle and tunnel span.This study provides a theoretical foundation and a novel calculation framework that explicitly quantifies the influence of meso-structural interlocking on the macro-mechanical behavior of moraine surrounding rock,thereby offering a more accurate basis for engineering design.
