Chapter 4- Slope Stability

BFC34402

CHAPTER 4.0 SLOPE STABILITY 

4.1 4. 1

TYPE TYPES S & CAUS CAUSES ES OF SL SLOP OPE E FAI FAIL LURE URE

%lope failures ma&or categories 1. Fall. This is the detachment of soil and/or rock fragments that fall down a slope. 2. Topple. This is a forward rotation of soil and/or rock mass about an axis  below the center of gravity of mass  being displaced. 3. Slide. This is the downward movement of a soil mass occurring on a surface of rupture. 4. Spread. This is a form of slide by translation. t occurs by !sudden movement of water"bearing seams of sands or silts overlain by clays or

Topple Fall

Slide

Spread

Flow

4.1 4. 1

TYPE TYPES S & CAUS CAUSES ES OF SL SLOP OPE E FAI FAIL LURE URE

%lope failures ma&or categories 1. Fall. This is the detachment of soil and/or rock fragments that fall down a slope. 2. Topple. This is a forward rotation of soil and/or rock mass about an axis  below the center of gravity of mass  being displaced. 3. Slide. This is the downward movement of a soil mass occurring on a surface of rupture. 4. Spread. This is a form of slide by translation. t occurs by !sudden movement of water"bearing seams of sands or silts overlain by clays or

Topple Fall

Slide

Spread

Flow

4.1 4. 1

TYPE TYPES S & CAUS CAUSES ES OF SL SLOP OPE E FAI FAIL LURE URE

4.1.1 Ty Types pes of of slope slope failure failure

a) Tran ransla slatio tional nal slide: slide: i. Failu ailurre alo alon n a !ea !ea" " #on #one e o$ o$ soi soil. l. ii. Slidin Slidin %ass %ass an tra'el tra'el lon lon dist distan anes es (e$ore o%in to rest. iii. iii. Co%%on Co%%on in ours ourse erai rained ned soil. soil. () Fl Flo! o! sl slid ide: e: i.

Ou Ours rs !*en !*en in inte tern rnal al & e+t e+ter erna nall ondition $ore a soil to (e*a'e li"e a 'isous ,uid & ,o! do!n. ii. -ulti -ultile le $ailur $ailure e sur$ sur$ae aes s usua usuall/ ll/ our our & *ane ontinuousl/ as ,o! roeeds.

4.1

TYPES & CAUSES OF SLOPE FAILURE

4.1.1 Types of slope failure

) Rotational slide: i.

Co%%on in *o%oenous 0nerained soil. ii.  t/es o$ rotational slides2 1. 3ase slide:  3/ an ar* enul0n t*e !*ole sloe.  A so$t soil restin on sti la/er. 5. Toe slide:  Failure sur$ae asses t*rou* t*e toe o$ sloe . Sloe slide:

4.1

TYPES & CAUSES OF SLOPE FAILURE

4.1.2 'auses of slope failure

1) 5) ) 4) 9) )

Erosion 6a & () Rain$all 6) Eart*7ua"e 6d) 8eoloial $eatures 6e) E+ternal loadin 6$) Constrution ati'ities 6) ;) Raid dra!do!n 6*)

4.5

STA3ILITY OF I