摘要
为计算岩溶区路基极限承载力,根据上、下限定理,结合有限元方法,基于MATLAB平台编制了相关计算程序。采用修正的Hoek-Brown准则来描述岩体的非线性特点,并将其嵌入到计算程序中。在此基础上,用无量纲参数Nσ、η衡量单个溶洞对路基承载力的影响,并详细分析了各参数的影响。结果表明:Nσ随着D/L(厚跨比)、GSI(地质强度指标)的增大而非线性增大,随H/L(高跨比)的增大而减小,与mi大致成线性关系;当D/L较小时,η随α(旋转角度)的增大先增大后减小;当D/L较大时,α对η的影响不大;岩石的物理力学参数GSI、mi、γ对η的影响可忽略不计。极限破坏模式可分为顶板冲切破坏、顶板冲切和侧壁联合破坏、顶板冒落和侧壁联合破坏。将条形基础作用在岩层的承载力的结果与已有成果进行对比,误差在3%以内,验证了本文所提方法的正确性。同时,为便于实际工程设计,提供了具体的设计表格,基本能满足大部分工程需求。
In order to calculate the limit bearing capacity of subgrade in the karst areas,combining the theorem of the limit analysis with finite element method,the computation procedure was provided based on MATLAB. The modified Hoek-Brown criterion was adopted to describe the non-liner char-acteristic of the rock mass,which was also embedded into the computation procedure. On this basis,dimensional parameters N_σ and η were defined to estimate the effect of voids on the bearing capacity of subgrade,and the effect of different parameters was also analyzed in detail. The results reveal that N_σ non-linely increases with increasing the values of D/L(the ration of thickness to span)and GSI(the geological strength index),and decreases with increasing the value of H/L(the ratio of height to span),and the linear relation between N_σ and mi. The value of η first increases,then decrease with an increase in the value of α,when D/L has smaller values. The value of α(rotation angle)has a little in-fluence on η,when D/L has larger values. The physical mechanics parameters(GSI,miand γ)of rock mass has a negligible effect on η. The failure mechanics could be classified punch failure of roof,combined roof punch and side wall failure,combined roof falling and side wall failure. The results of bearing capacity for strip footing on a rock mass are compared with previous study,and the difference within 3%. This indicates that the method proposed in this paper is correct. Meanwhile,for the conve-nience of design in engineering practice,design tables are provided,which could be meet most require-ments in engineering practice.
作者
蒋德松
胡可馨
赵明华
张锐
赵衡
JIANG Desong;HU Kexin;ZHAO Minghua;ZHANG Rui;ZHAO Heng(Geotechnical Engineering Institute of Hunan University,Changsha 410082,China;School of Civil Engineering,Central South University,Changsha 410075,China)
出处
《防灾减灾工程学报》
CSCD
北大核心
2020年第4期596-605,共10页
Journal of Disaster Prevention and Mitigation Engineering
基金
国家自然科学基金项目(51478178,51608540)资助。
关键词
溶洞
旋转角度
路基
承载力
有限元极限分析
void
rotation angle
subgrade
bearing capacity
finite element limit analysis
作者简介
蒋德松(1972-),男,副教授,硕士。主要从事岩溶路基处理方面的研究。Email:jiangdesong@hnu.edu.cn。
