An excavation on the landside is risky. During a flood, the clay acts as a confining layer, because it has lower permeability than the sand. The water wants to punch through the clay, i.e. there is an uplift gradient on the base of the clay layer. The resistance of the clay layer to this...
You are mistaken. The water pressure in the chamber acts equally in all directions (radially and vertically). It acts on the top and bottom caps just the same as it does on the sides of the sample. Consolidation is not just a "vertical thing"; it's horizontal as well. When you consolidate...
So total head at the top of the cylinder is 30cm. No headloss from top of water to top of soil, so total head at top of soil = 30 cm. Elevation head = 20 cm, pressure head = 10 cm. Total head drops from 30 cm to 0 cm over 20 cm of soil, so the gradient = i = delta H / L = 30 cm /20 cm = 1.5...
Is water flowing through the column? If water is NOT flowing through the column, then YES, the total head is the same at all elevations. Total head = Elevation head + Pressure head. At El. 0m, Pressure head = 30m, Total head = 0 + 30 = 30m. At El. 15m, Pressure head = 15m, Total head = 15 +...
1. Typically you will load in increments that double the previous load, and unload in increments of 4, so a typical load sequence would be 10, 20, 40, 80, 160, 320, 640, 1280, 320, 80, 20, 10 kPa. At a minimum you would want to get at least 2 loads past the preconsolidation pressure so you...
1. Hard to say without looking at the curve and the beginning and ending loads. If you are unsure, you have the budget, and it's critical enough, then yes, you may want to consider a retest. What I mean by envelope is to bound your stresses. If you are loading to X kPa, you want to load it...
Holtz and Kovacs has a great discussion on consolidation. There are other great texts as well. As for your questions:
1. If you reach virgin compression (past the preconsolidation pressure) in the test, you would probably be OK from a magnitude of settlement perspective, maybe less so on the...
Soils from the same geologic origin and mineralogy will generally plot in a straight line on a plasticity chart (LL vs PI). Often the line is roughly parallel to the A-Line (dividing line between silt and clay). You can probably make your own correlation for your local soils, but using data...
8H seems in the right ballpark of an inverted triangular pressure distribution (8H psf at the top, 0 at the bottom) that is added to the EFP, coming from a Mononobe-Okabe solution for earthquake pressure. You are right, the pressure should be greater for a non-yielding wall. I believe AASHTO...
Two stories similar to jgailla:
1. I was in a rush and in on markup drew a bunch of freehand lines seemed to me to be pretty straight, and in context of the drawing were obviously (even to a drafter) supposed to be straight. I got the drawing back with wavy lines. I went back to the drafter...
I suggest some introspection, and thinking about what kind of clients and jobs you are pursuing, and what value you add over the "other guy". If the work you are pursuing is amendable to the cookie-cutter methods the other guy is using, then are the projects technically challenging enough to...
