The discrete element method is particularly effective for simulating the nonlinear deformation of heterogeneous rock slopes subjected to gravitational loads following open-pit mining. Traditional methodologies often suffer from ambiguous criteria for determining slope instability,thereby complicating the accurate assessment of the slope’s safety factor. To address this issue,a cusp catastrophe model was developed,establishing a relationship between the average horizontal displacement of the slope and the gravitational coefficient. This model quantifies the critical instability criterion as a definitive displacement catastrophe value. Using the discrete element program MatDEM,simulations were conducted with varying combinations of joint spacing and connectivity to examine the changes in critical displacement and safety factors under different conditions. Case analyses indicate that this model effectively determines the critical displacement and corresponding safety factor at the point of slope failure. Notably,when joint connectivity is 0.70,the critical instability displacement is generally higher compared to scenarios with greater connectivity. For joint spacings ranging from 1 to 3 meters,an increase in spacing results in a larger sliding mass along the joint surface,which consequently leads to a rise in the critical instability displacement. The gravity increase method,grounded in cusp catastrophe theory,models the evolution of slopes under realistic conditions by incrementally increasing the gravitational load. This approach is particularly well-suited for jointed rock masses that exhibit complex nonlinear deformation behaviors. Unlike the strength reduction method,it obviates the need for recalibrating material parameters before each calculation,thereby enhancing computational efficiency. The study’s findings indicate that joint spacing and connectivity have a significant impact on slope stability. With uniform joint spacing,increased connectivity results in a lower safety factor,whereas with uniform connectivity,larger joint spacing leads to a higher safety factor. These findings are consistent with practical engineering conditions,underscoring the importance of considering joint spacing and connectivity in slope stability analysis.The developed model and results provide a scientific basis for determining monitoring point placement and setting warning thresholds for slope displacement in jointed rock mass regions.
离散元法(Discrete Element Method,DEM)能详细模拟岩体破裂、滑动等局部及整体响应,因此被广泛应用于边坡稳定性工程领域。在以往研究中,研究人员通过引入数值方法和理论模型对边坡稳定性进行了若干探索。一方面,通过将离散元法配合强度折减法和重力增加法等数值技术应用于估计边坡安全系数,揭示了在模拟进程中岩体内部破裂及失稳的演化过程(周健等,2009;Scholtès et al.,2012)。另一方面,针对边坡稳定性的判据问题,提出了基于位移突变的失稳判据,尝试通过监测位移响应来识别临界失稳状态(徐卫亚等,2007;Li et al.,2023)。与此同时,非线性动力学理论尤其是尖点突变模型被引入解释岩体在外界荷载作用下参数的突变特征,为判断斜坡失稳提供了新的理论依据(秦四清,2000;Qin et al.,2001)。尽管上述研究为揭示复杂岩体失稳机制做出了积极探索,但是所采用的方法在量化临界失稳阈值、明确安全系数指标方面仍存在不足,难以直接应用在实际工程中。
式中:宏观参数包括弹性模量()、泊松比()、抗拉强度()、抗压强度()和内摩擦系数();细观参数包括正向刚度()、切向刚度()、断裂位移()、初始抗剪力()和颗粒单元直径()。岩体具体的物理力学参数见表1,细观参数转换结果见表2,模型颗粒半径取值为0.05 m,各参数训练值与实际值平均相对误差为4.46%。生成节理时使用光滑节理模型,将筛选出的节理范围内颗粒黏结移除(Asadi et al.,2012)。颗粒单元连接情况如图2所示。
AsadiM S, RasouliV, BarlaG,2012.A bonded particle model simulation of shear strength and asperity degradation for rough rock fractures[J].Rock Mechanics and Rock Engineering,45(5):649-675.
[2]
ChenZhonghui, TangChun’an, FuYufang,1997.Study on sudden jump of deformation in unstable failure of rocks[J].Journal of Engineering Geology,5(2):143-149.
[3]
DuShigui,2018.Method of equal accuracy assessment for the stability analysis of large open-pit mine slopes[J].Chinese Journal of Rock Mechanics and Engineering,37(6):1301-1331.
[4]
HuBo, ZhangNan, WangSijing,et al,2011.Model test and strength analysis research on intermittent joint rock mass[J].Chinese Journal of Underground Space and Engineering,7(4):657-665.
[5]
JingYongbin, ZhaoXintao, FengXinglong,2018.Study on 3D simulation of rock fraghmentation for jointed rock mass[J].Gold Science and Technology,26(3):357-364.
[6]
LiM, YueZ F, JiH G,et al,2023.Numerical analysis of interbedded anti-dip rock slopes based on discrete element modeling:A case study[J].Applied Sciences,13(23):12583.
[7]
LiYuqian, LiGuangyuan,2014.Application of FEM gravity increase method in stability analysis of inhomogeneous slopes[J].Science Technology and Engineering,14(33):290-293,299.
[8]
LingFuhua,1984.Catastrophe theory:History,current situation and future[J].Advances in Mechanics,14(4):389-404.
[9]
LiuChun, LeTiancheng, ShiBin,et al,2020.Discussion on three major problems of engineering application of the particle discrete element method[J].Chinese Journal of Rock Mechanics and Engineering,39(6):1142-1152.
[10]
MengYongdong, SuQingming, LuWeiping,et al,2015.Research on improved grain flow gravity increase method[J].Water Resources and Power,33(2):149-151.
[11]
QinS, JiaoJ J, WangS,2001.A cusp catastrophe model of instability of slip-buckling slope[J].Rock Mechanics and Rock Engineering,34(2):119-134.
[12]
QinSiqing,2000.Nonlinear catastrophy model of slope instability and chaotic dynamics mechanism of slope ecolution process[J].Chinese Journal of Rock Mechanics and Engineering,19(4):486-492.
[13]
ScholtèsL, DonzéF V,2012.Modelling progressive failure in fractured rock masses using a 3D discrete element method[J].International Journal of Rock Mechanics and Mining Sciences,52:18-30.
[14]
ShengJianlong, ZhaiMingyang,2018.Reliability analysis and sampling method comparison of Jinjiling rock slop based on stochastic response surface method[J].Gold Science and Technology,26(3):297-304.
[15]
SunJietao, LiHaifeng,2024.Study on stability of rock slope based on safety and stability rate[J].Chinese Journal of Rock Mechanics and Engineering,43(Supp.2):3872-3884.
[16]
SwanC C, SeoY K,1999.Limit state analysis of earthen slopes using dual continuum/FEM approaches[J].International Journal for Numerical and Analytical Methods in Geomechanics,23(12):1359-1371.
[17]
WangXuyi, HuangShuling, DingXiuli,et al,2021.Study on the effect of inhomogeneous bedding plane on the mechanical properties of uniaxial compression of layered rock mass[J].Rock and Soil Mechanics,42(2):581-592.
[18]
WangZhengtang, ZhangQi, WangChenlong,et al,2021.Influence of joint geometrical parameters on mechanical properties of rock mass[J].Chinese Journal of High Pressure Physics,35(6):145-157.
[19]
XuWeiya, XiaoWu,2007.Study on slope failure criterion based on strength reduction and gravity increase method[J].Rock and Soil Mechanics,28(3):505-511.
[20]
ZhouJian, JiaMincai,2008.Experimental Investigation and Numerical Simulation of Mesoscopic Models in Geotechnical Engineering[M].Beijing:Science Press.
[21]
ZhouJian, WangJiaquan, ZengYuan,et al,2009.Slope safety factor by methods of particle flow code strength reduction and gravity increase[J].Rock and Soil Mechanics,30(6):1549-1554.