2.11: Summary
- Page ID
- 33353
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)
( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\id}{\mathrm{id}}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\kernel}{\mathrm{null}\,}\)
\( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\)
\( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\)
\( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)
\( \newcommand{\vectorA}[1]{\vec{#1}} % arrow\)
\( \newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow\)
\( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vectorC}[1]{\textbf{#1}} \)
\( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)
\( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)
\( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Figure 2-57 gives a summary of the Mohr circles for Active and Passive failure of a cohesion less soil.

Some equations for a cohesion less soil in the active state:
Failure will occur if:
\[\ \sin (\varphi)=\frac{\frac{1}{2} \cdot\left(\sigma_{\mathrm{v}}-\sigma_{\mathrm{h}}\right)}{\frac{1}{2} \cdot\left(\sigma_{\mathrm{v}}+\sigma_{\mathrm{h}}\right)}\tag{2-114}\]
This can also be written as:
\[\ \left(\frac{\sigma_{\mathrm{v}}-\sigma_{\mathrm{h}}}{2}\right)-\left(\frac{\sigma_{\mathrm{v}}+\sigma_{\mathrm{h}}}{2}\right) \cdot \sin (\varphi)=0\tag{2-115}\]
Using this equation the value of σh can be expressed into σv:
\[\ \sigma_{\mathrm{h}}=\sigma_{\mathrm{v}} \frac{1-\sin (\varphi)}{1+\sin (\varphi)}=\mathrm{K}_{\mathrm{a}} \cdot \sigma_{\mathrm{v}}\tag{2-116}\]
On the other hand, the value of σv can also be expressed into σh:
\[\ \sigma_{\mathrm{v}}=\sigma_{\mathrm{h}} \frac{1+\sin (\varphi)}{1-\sin (\varphi)}=\mathrm{K}_{\mathrm{p}} \cdot \sigma_{\mathrm{h}}\tag{2-117}\]
For the passive state the stresses σv and σh should be reversed.
Figure 2-58 gives a summary of the Mohr circles for Active and Passive failure for a soil with cohesion.

Some equations for a soil with cohesion in the active state:
Failure will occur if:
\[\ \sin (\varphi)=\frac{\frac{1}{2} \cdot\left(\sigma_{\mathrm{v}}-\sigma_{\mathrm{h}}\right)}{\mathrm{c} \cdot \cot (\varphi)+\frac{1}{2} \cdot\left(\sigma_{\mathrm{v}}+\sigma_{\mathrm{h}}\right)}\tag{2-118}\]
This can also be written as:
\[\ \left(\frac{\sigma_{\mathrm{v}}-\sigma_{\mathrm{h}}}{2}\right)-\left(\frac{\sigma_{\mathrm{v}}+\sigma_{\mathrm{h}}}{2}\right) \cdot \sin (\varphi)-\mathrm{c} \cdot \cos (\varphi)=0\tag{2-119}\]
Using this equation the value of σh can be expressed into σv:
\[\ \sigma_{\mathrm{h}}=\sigma_{\mathrm{v}} \frac{1-\sin (\varphi)}{1+\sin (\varphi)}-2 \cdot \mathrm{c} \cdot \frac{\cos (\varphi)}{1+\sin (\varphi)}=\mathrm{K}_{\mathrm{a}} \cdot \sigma_{\mathrm{v}}-2 \cdot \mathrm{c} \cdot \sqrt{\mathrm{K}_{\mathrm{a}}}\tag{2-120}\]
On the other hand, the value of σv can also be expressed into σh:
\[\ \sigma_{\mathrm{v}}=\sigma_{\mathrm{h}} \frac{1+\sin (\varphi)}{1-\sin (\varphi)}+2 \cdot \mathrm{c} \cdot \frac{\cos (\varphi)}{1-\sin (\varphi)}=\mathrm{K}_{\mathrm{p}} \cdot \sigma_{\mathrm{h}}+2 \cdot \mathrm{c} \cdot \sqrt{\mathrm{K}_{\mathrm{p}}}\tag{2-121}\]
For the passive state the stresses σv and σh should be reversed.