Geo Hw

Jackie Wong
ID 0371203

1. PROBLEM 7.2

Given:

L=300 mm h=500 mm
A=175 cm2

Water collected in 3min=620 cm3
Void ratio of sand=0.58

Determine: a) Hydraulic conductivity, k (cm/sec) k=QLAht=620 cm3*30 cm175cm2*50cm*3min*60sec1min=0.0118cmsec b) Seepage velocity vs=v1+ee, v=ki, i=hL→vs=khL1+ee=0.011850cm30cm1+0.580.58=

vs=0.0536 cm/sec

2. PROBLEM 7.6

GIVEN-Falling head permeability test:

Length of soil specimen=700 mm
Area of the soil specimen=20cm2
Area of the standpipe=1.05 cm2
∆h at time t=0 is 800mm
∆h at time t=8minis 500 mm

Assume that the test was conducted at 20℃, and at 20℃, γw=9.789kNm3and η=1.005*10-3 N*sm2.

Determine: a) Absolute permeability of the soil k=2.303aLAtlog10h1h2=2.3031.05*7020*8log10800500=0.216 cm/min
K=kηγw=0.216cmmin*1min60sec1.005*10-3 N*sm29.789kNm3=3.7*10-10m2 b) What is head difference at time t=6min? k=2.303aLAtlog10h1h2→0.216cmmin=2.3031.05*7020*6log10800h2 h2=562.3 mm 3. PROBLEM 5.2

Eq 5.1:GI=F200-350.2+0.005LL-40+0.01F200-15(PI-10)
Eq 5.2:GI=0.01F200-15PI-10
Rules:
1. If Eq. 5.1 yields a negative value for GI, it is taken as 0. 2. The group index calculated from Eq. 5.1 is rounded off to the nearest whole number. 3. There is no upper limit for the group index 4. The group index of soils belonging to groups A-1-a, A-1-b, A-2-4, A-2-5, and A-3 is always 0. 5. When calculating the group index for soils that belong to groups A-2-6 and A-2-7, use the partial group index for PI, or Eq. 5.2.
Classify the soils using the AASHTO classification system and give the group index:

Sample Calculation for Soil No. 1:
PI=LL-PL=38-29=9
From Table 5.1→F200=50>36 min., LL=38<40max, PI=9<10max
Soil No.1 is A-4(GI)
GI=F200-350.2+0.005LL-40+0.01F200-15PI-10
=50-350.2+0.00538-40+0.0150-159-10
GI=2.5→rounded to 3→Classification of Soil No.1 is A-4(3)

Sieve analysis (percent finer) | Soil No. | No. 10 | No. 40 | No. 200 |