Intro Doc
$\underline{Earth Retaining Structure - Case 8}$ $\\$ $\bullet$Braced Wall in Soft Cohesive Soil: $\\$ This program indicates if the design is acceptable for a braced wall in clay. There are two specific clay layers defined. This data was obtained from the automation of a manual developed to simplify the design process of temporary earth retaining systems.To start, this program uses the free-earth design method which assumes that the piles will develop along the whole length of the pile. $\\$ Step 1: Input the soil parameters and staged construction excavation depths. The inputs that are required for this are the depth of excavation (depth), the width of the excavation (width), the locations of the struts (Strut_i),the depth from the last strut to the bottom of the excavation (To_bottom),the depth to the water table (D_w), the depth from the bottom of the excavation to the end of the piling (D), the overall length of the piling (L), the soil parameters for each layer, and the design factor of safety (FOS). $\\$ Step 2: The program computes the active and passive earth pressure coefficients. (With clay they will both be equal to 1.0) $\\$ Step 3: Calculate the critical height. The critical height determines the depth in which the pile is able to hold back the earth and hydrostatic pressures without collapsing. Excavating beyond the critical height will lead to failure. To do this use the following equation for the critical height. $\\$ \begin{equation}\label{eq1} Hc =\frac{2 \cdot c-surcharge}{gamma} \end{equation} $\\$ Step 4: Calculate the active and passive soil pressures at different lengths along the depth of the piling. Using the following equations: $\\$ \begin{equation}\label{eq2} sigma_ai = Ka \cdot gamma \cdot z \end{equation} $\\$ Where z is the depth to the location where you are finding the soil pressure. \begin{equation}\label{eq3} sigma_pi=2 \cdot c+Kp \cdot H \cdot gamma \end{equation} $\\$ Step 5: Calculate the bending moments along the pile. This was given information within the manual from SupportIT software. These would have to be calculated using a similar software of be calculated manually and input into the code. $\\$ Step 6: Begin preparing for the strut force calculations by determining which case of the Terzaghi-Peck apparent pressure diagrams is used. The following equation will be used to determine if it's case A, B, or C: $\\$ \begin{equation}\label{eq4} NS= \frac{gamma \cdot H}{c} \end{equation} $\\$ Step 7: A new factor also defined as Ka will need to be calculated using the following equation: $\\$ \begin{equation}\label{eq5} Ka= 1- \frac{4 \cdot m}{NS} \end{equation} Where m is equal to 1.0. $\\$ Step 8: Calculate the pressures along the apparent pressure diagram, using the following equation: $\\$ \begin{equation}\label{eq6} sigma_asoil= Ka \cdot gamma \cdot H \end{equation} Using the new Ka defined in step 7. $\\$ \begin{equation}\label{eq7} sigma_ surcharge= surcharge \end{equation} $\\$ \begin{equation}\label{eq8} sigma_ total= sigma_asoil+sigma_ surcharge \end{equation} $\\$ Step 9: Calculate the strut forces using statics from the apparent pressure diagram. $\\$ Step 10: Determine the critical height for each soil layer. Use the following equation: $\\$ \begin{equation}\label{eq9} H_c= \frac{5.7 \cdot c}{gamma- \sqrt{2} \cdot \frac{c}{B}} \end{equation} $\\$ Step 11: Calculate the factor of safety in each soil layer and compare it to the design factor of safety. $\\$ \begin{equation}\label{eq10} FOS= \frac{H_c}{H} \end{equation}