Geotechnical Engineering

DHARM 320 GEOTECHNICAL ENGINEERING Shear stress Unstable slope Mohr-coulomb strength envelope Stable slope f b s t Normal stress ...

DHARM STABILITY OF EARTH SLOPES 321 Effective normal stress σn = (σn – u) = (γz cos^2 β – u) (γ is the average unit weight of th ...

DHARM 322 GEOTECHNICAL ENGINEERING The factor of safety against slippage may be written as: F =^1 − F HG I KJ = F − HG I KJ = ′ ...

DHARM STABILITY OF EARTH SLOPES 323 From Eq. 9.8, 1 = c γββzcsin cos or zc = c γββsin cos ...(Eq. 9.9) Thus for a given value of ...

DHARM 324 GEOTECHNICAL ENGINEERING For example, the depth z corresponding to the point T 2 is stable for the slope angle β > ...

DHARM STABILITY OF EARTH SLOPES 325 9.3 Finite Slopes A ‘finite slope’, as has already been defined, is one with a base and a to ...

DHARM 326 GEOTECHNICAL ENGINEERING Let AB be a trial slip surface (a circular arc of radius r) as shown in Fig. 9.8. q O r A B e ...

DHARM STABILITY OF EARTH SLOPES 327 The depth of tension crack is given by: hc = 2c/γ ...(Eq. 9.18) (The concept and derivation ...

DHARM 328 GEOTECHNICAL ENGINEERING For example, the values for all slices may be tabulated as follows and summed up: Slice no. A ...

DHARM STABILITY OF EARTH SLOPES 329 1.56 1.54 1.52 1.50 1.65 1.60 1.70 1.57 1.57 Fig. 9.12 Location of centre of critical circle ...

DHARM 330 GEOTECHNICAL ENGINEERING Table 9.1 Fellenius’ values for α and δ for the different values of β S.No. Slope Angle of sl ...

DHARM STABILITY OF EARTH SLOPES 331 For soils with φ </ 3°, the critical slip circle is invariably through the toe. It is so ...

DHARM 332 GEOTECHNICAL ENGINEERING The pore pressure ratio ru can be easily obtained from the flow net for this case, as shown i ...

DHARM STABILITY OF EARTH SLOPES 333 the sliding moment while it reduces the shear resistance mobilised by decreasing the effecti ...

DHARM 334 GEOTECHNICAL ENGINEERING ∴ ru = B ...(Eq. 9.28) The pore pressure coefficient B may be determined from a triaxial test ...

DHARM STABILITY OF EARTH SLOPES 335 The shear resistance (stress) mobilised is: τ = cu F ′+()tanσφn− ′ Total normal stress σn on ...

DHARM 336 GEOTECHNICAL ENGINEERING Since this equation contains F on both sides, the solution should be one by trial and error. ...

DHARM STABILITY OF EARTH SLOPES 337 q R f r r sinf r W C=c.mm l q R f r r sinf r Fig. 9.19 Concept of friction circle Fig. 9.20 ...

DHARM 338 GEOTECHNICAL ENGINEERING The value of k may be obtained from Fig. 9.22. 120 1.16 1.12 1.08 1.04 1.00 0 20 40 60 80 100 ...

DHARM STABILITY OF EARTH SLOPES 339 q O r lc W T f R C=cmmc l a R W Cm (a) Resultant cohesive force and other forces (b) Triangl ...