20 slope This question involves performing a design calculation critical to earthwork operations. You are the constructi

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20 Slope This Question Involves Performing A Design Calculation Critical To Earthwork Operations You Are The Constructi 1 (86.69 KiB) Viewed 48 times

20 slope This question involves performing a design calculation critical to earthwork operations. You are the construction engineer for a project to install a stormwater pipeline for pipe storage Montgomery County. This involves excavating an unsupported trench in a native CH soil, installing the pipe, and 107 Existing ground surface backfilling the trench. The contractor is storing 35 concrete pipes adjacent to the H=15ft trench location, and near an existing New vertical private residence. Due to scheduling, the excavation must be made now. It needs to stand vertically for about 1 month before it can be backfilled. The stored pipes (8 ft long, 2.120 lb each) are estimated to apply a uniformly distributed vertical load at the ground surface of q = 450 psf. Part 1. Will the vertical cut of H=15 feet be stable just after excavation (ie, in the short term)? The factor of safety (FS) must be greater than 1.3 to be considered stable. Assume Suis 1,000 psf and the saturated unit weight is 105.8 pcf. Use the wedge stability analysis method we discussed in class to evaluate the factor of safety when a = 90 degrees. The analysis must include computation of factor of safety over a range of trial failure plane orientations, plotting the values to find the minimum. For guidance, vary B in 5-degree increments from 20 degrees to 60 degrees and plot the resulting values of FS against B. Find the minimum FS on the resulting curve. Part 2. For the most critical failure plane only, what is the the impact of storing the pipes next to the excavation on the factor of safety? Please provide justification for your answer by evaluating the stability for this one failure plane without the surcharge of the pipes. Part 3. What are at least two uncertainties in your analysis that would influence the factor of safety? Explain each. Part 4. Does a failure of the trench along the most critical failure plane have any potential consequences for the house?