基于改进BP算法的岩石宏细观参数轻量化分析方法  

Lightweight Analysis Method for Rock Macro-Meso Parameters Based on Improved BP Algorithm

作　　者：任俊卿 肖明[1] 刘国庆 REN Junqing;XIAO Ming;LIU Guoqing(State Key Laboratory of Water Resources Engineering and Management,Wuhan University,Wuhan 430072,China;State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin,China Institute of Water Resources and Hydropower Research,Beijing 100048,China)

机构地区：[1]武汉大学水资源工程与调度全国重点实验室,湖北武汉430072 [2]中国水利水电科学研究院流域水循环模拟与调控国家重点实验室,北京100048

出　　处：《湖南大学学报（自然科学版）》2023年第9期207-218,共12页Journal of Hunan University:Natural Sciences

基　　金：国家自然科学基金资助项目(52079097);国家重点基础研究发展计划资助项目(2015CB057904)。

摘　　要：针对PFC3D细观参数多、宏细观参数间影响机制分析难度大、参数标定模型可解释性不足等问题,以细观参数轻量化分析目标,通过引入含陡度因子的功能函数、自适应Nest-erov动量法及自适应学习率提出了一种改进的BP算法进行轻量化建模.与传统BP算法对比表明:改进算法提升了传统算法的稳定性与收敛速度,能够合理准确的对宏细观参数间的敏感性进行量化,筛选出关键的细观参数并获得轻量化的宏细观参数分析模型.基于轻量化模型对宏细观参数间的相关性及影响机制进行分析,研究了单个及多个关键细观参数对宏观参数的影响规律,研究发现:弹模随等效模量增大呈线性增长;平行黏结刚度比对弹模的增长具有抑制作用且当刚度比较高时弹模减小幅度较大.泊松比和颗粒刚度比及平行黏结刚度比间均存在线性关系,而摩擦系数的增大将引起泊松比的非线性减小.强度参数对峰值强度均具有激励作用,当平行黏结抗拉及抗剪强度在较高水平下的组合对峰值强度的提升作用最为显著,内摩擦角主要对岩石的峰后强度具有一定影响,这是由于试样在峰后加载时,内摩擦角对于剪切带两侧的颗粒滑动具有一定的控制作用.研究成果对于PFC参数标定问题具有一定的参考价值.Aiming at the problems of many meso parameters of PFC 3D,difficulty in analyzing the influence mechanism between macro and meso parameters,and insufficient interpretability of parameter calibration model,an improved BP algorithm is proposed employing the function with steepness factor,adaptive Nesterov momentum method and adaptive learning rate for lightweight analysis of meso parameters.The comparison with the traditional BP algorithm shows that this algorithm improves the stability and convergence speed of the traditional algorithm and can reasonably and accurately quantify the sensitivity between macro and meso parameters,screen out the key meso parameters and obtain a lightweight macro-meso parameter analysis model.Based on the lightweight model,the correlation and influence mechanism between macro and meso parameters are analyzed,and the influence law of single and multiple key meso parameters on macro parameters is studied.The research shows that the elastic modulus increases linearly with the increase of the equivalent modulus.The parallel bond stiffness ratio can inhibit the growth of elastic modulus,and the elastic modulus decreases greatly when the stiffness is relatively high.There is a linear relationship between Poisson´s ratio and stiffness ratio,and the increase of friction coefficient causes the nonlinear decrease of Poisson´s ratio.The strength parameters have an incentive effect on the peak strength.The combination of the parallel bond tensile and shear strength at a high level has the most significant impact on the increase in the peak strength.The internal friction angle mainly has an influence on the post-peak strength of the rock.The internal friction angle has a certain control effect on the particle sliding on both sides of the shear zone when the sample is loaded after the peak.The research results have reference values for PFC parameter calibration.

关 键 词：PFC3D 岩石 改进BP算法 自适应算法 宏细观 轻量化 标定 

分 类 号：TU452[建筑科学—岩土工程]