土力学(中英文对照)-- Chapter 7 Slope Stability Part

N
平行)
▪ Factor of safety (Fs) is expresseStability of an infinite slope (无限长边坡稳定分析)
▪ If ground water table exists and coincides with the surface of the slope (地下水位与坡面相同)
Fs
Mr Md
Tr W r sin
T W sin
c'' tan' l W sin
c'L tan' N'
W sin
W T
N’
7.5 Method of slices (条分法)
▪ The forces acting on a vertical slice of soil mass are shown as follows: (某一个土条上力的分布如下)
7.5 Method of slices (条分法)
▪ Total weight of the slice (土条重量) W = bh
▪ Effective normal force on the base (有 效法向力) N’ = ’l
▪ Hydrostatic force on the base (静水力) U = ul where u is pore-water pressure at the center of the base
Limit equilibrium method (极限平衡法)
▪ For the slope stability analysis using the LEM, two analyses are considered for each slope: ▪ Effective Stress Analysis (c´ and ´) that represents drained or long-term behaviour of the slope (有效应 力分析考虑排水,对应边坡长期的稳定) ▪ Total Stress Analysis (cu) that represents undrained or short-term behaviour of the slope (总应力分析不考 虑排水,对应边坡短期的稳定)
Limit equilibrium method (极限平衡法)
▪ A slip surface is assumed and forces on this sliding soil mass are solved by considering force equilibrium . (在某 一假设滑动面上,用静力平衡法求滑动面上的法向力 与剪切力)
Total stress analysis, u = 0 (总应力分析)
▪ Consider a circular slip surface: center O, radius r and length of arc L is shown below. (下图为一假设圆弧滑动 面:圆心为O,半径为r,弧长为L)
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▪ Factor of safety (Fs) is defined as (安全糸数定义为)
shearstrength 抗剪强剪 Fs shearstress 下滑剪切力
▪ The most critical slip surface gives the minimum Fs (最危险滑动面对应最小安全糸数)
b ▪ Factor of safety (FS) is expressed as:
' tan Fs s tan
W
z
T
N’ U
▪ The factor of safety is reduced by a factor ’/s if the water table rises to the slope surface.
▪ Shear force on the base (剪切力) T ▪ Total normal forces on the sides (法向
条间力) E1 and E2 ▪ Shear forces on the sides (切向条间力)
Chapter 7 Slope Stability (边坡稳定) - Part 2
In this lecture, we’ll learn ▪ Methods of slices (条分法) ▪ Fellenius (or Swedish) solution (瑞典条分法 ) ▪ Bishop routine solution (毕肖普条分法) ▪ Short-term and long-term stability of a slope (短期 与长期的边坡稳定:参土力学p.213图7-18)
度小)
b
▪ Assumptions (假定):
▪ no ground water table (没有地下水) ▪ homogeneous cohesionless soil (均质
W
z
无粘性土)
T
▪ failure surface is parallel to the surface of the slope (滑动面与坡面
O
dW
Fs
cu Lr Wd
7.5 Method of slices (条分法)
▪ For 0, method of slices can be used where the soil
mass above the assumed slip surface is divided into a series of vertical slices (当 0时,滑动块体分成多个垂 直的土条) ▪ The factor of safety (Fs) is defined as
Stability of an infinite slope (无限长边坡稳定分析)
▪ For an infinite slope, the depth of the
failure surface is small compared with the
length of the slope (滑动面深度比边坡长