Seepage from River to excavation pit

[Geo11]

I have to check the stability of excavation with 1.5h: 1v cut-slope and 100 feet feet from the river bed (on top). I am trying to perform seepage analysis using flow net. Most of books give example for equal level of bottom height (earth dam). I appreciate for suggestion how can i use same method for my case where bottom of u/s and d/s level are on different level. My main concern is construction of phreatic line.

 

[fattdad]

I'd suggest figures 4-2 or 4-3 in the publication linked below:

http://armypubs.army.mil/eng/DR_pubs/dr_a/pdf/tm5_818_5.pdf

I'd expect you'd have sumps at the tow of the excavation (well points?) so you use of "stability" relates more to the slope stability rather than stability against piping (i.e., critical gradient stuff). If you are really dealing with a 100-ft by 100-ft square excavation and the water table is uniform on all sides of the excavation, you can use flow to well equations (see later figures in the linked reference). In other words in flow to well analyses, you'd use an equivalent radius of 56 ft, 'cause a radius of 56 ft yields the same area as a 100x100 ft pit.

f-d

¡papá gordo ain’t no madre flaca!