CLAY

= 114 pcf

e=0.55

SAND

γ d

= 132 pcfγ sat

14 ftH

10 ft

8 ft

A

B

Rutgers University 180:372Department of Civil & Env. Engineering Name_______________________________

SOIL MECHANICS

MIDTERM EXAM - Spring 2000

Instructions: Closed book exam except for one sheet of notes. Use the space below eachquestion for essential calculations. Any graphs or charts you may need are attached. Scoringweights are shown in the margin. Answers must be supported by your calculations.

1. (20) Find the maximum depth of excavation H before soil at the bottom starts heaving. What isgoing to be the rate of seepage in the vertical direction for the critical, if the excavation were 20 ftwide and 40 ft long, and a coefficient of permeability of the clay 0.000,005 in/s?

CLAY

SAND e = 0.55

4 m

3.2 m

S = 30%

1.5 m G = 2.67se = 0.55

= 17.4 kN/mγ d3

2. (30) Calculate and draw diagrams of distributions of: the total stress, the effective stress and porewater pressure for the soil system presented below.

12 m 8 m 6 m

8 m

8 m

A

3. (25) A new building is going to be constructed next to an existing one. The bottom of the slab ofthe new building is 6 m above the bottom of strip footings of the existing building. Calculate theincrease of the vertical pressure at corner A for the assumption that the new building slab will have

a u n i f o r m l ydistributed loading of120 kPa.

SAND

CLAYC = 1.1e = 0.85 c0

= 19.5 kN/m3γ sat

1 m

1.5 m

3.8 m

OCR = 1.4

3 m

ROCK

1.5 m

C = 0.15s

F = 1400 kN

= 19.7 kN/m3γ sat

= 17.0 kN/m3γ

4. (25) Calculate the ultimate settlement of the 3x3 m square foundation presented below for thegiven loading. (Do not divide the layer into sublayers.)