2016 - Soil Mechanics I and Exercises - Midterm Examination
2016/11/29 (Tue) 13:00-14:00 W2 Lecture RoomAttention: There are two answer sheets for two questions including sub-questions. Write down your name

and student ID number on both answer sheets. Use one answer sheet for one question andanswer them in the same order as the questions are posed, starting from [Question 1]. If thespace provided in the answer sheet is insufficient, use the back page after clearly mentioning so(for example, “continued on back page”).
In addition to writing utensils, rulers and scientific calculators are allowed on the exam.
However, programmable calculators or mobile phone calculators/applications are absolutely notpermitted.
Talking is not allowed at any time in the test. Any attempts at cheating on the test will result in
failed credit of the course and serious penalties.
Wherever necessary, specify the units in your answers.

[Question 1] Answer the questions below.
(1) Answer the following questions regarding the ground shown in Figure 1, using the densityof water ρw = 1.00×103 kg/m3 and the acceleration of gravity g = 9.80 m/s2.

Figure 11)

Soil experiments were carried out on the undisturbed samples taken from the groundabove the groundwater surface (unsaturated zone), giving the water content w = 18.0%,
the total density of soil ρt =1.80×103 kg/m3 and the particle density of soil ρs =2.70×103
kg/m3. Find the void ratio e and the degree of saturation Sr of this ground.

2)

Assuming that the ground below the groundwater surface (saturated zone) is fully
saturated, find the water content w and the wet (saturated) density of soil ρsat in thesaturated zone. Provided that the void ratio e and the soil particle density ρs do not change
along the depth, the values obtained from 1) may be used.

3)

Under the condition described in Figure 1, calculate total stress, pore water pressure andeffective stress at Point A (15 m deep from the ground surface).

(2) Explain briefly the following subjects and how they are obtained and measured in theexperiments.
1) Soil compaction curve2) Liquid limit3) Soil particle density[Question 2] Answer the following questions regarding flow of water through soils. Consider allsoil samples as fully saturated, and that the flow of water follows Darcy’s Law.
(1) As shown in Figure 2, the soil sample 1 is set in a permeability test apparatus. The cross sectionof the sample is 2.0 × 10-2 m2, and its lower part is supported by a metallic mesh. The hydraulicconductivity of soil 1 is k1 = 3.0 × 10-5 m/s. Find the flow rate through the system, given thehead difference shown in the figure.

0.1 m

Soilsample 1試料10.3 m

Figure 2(2) As shown in Figure 3, the soil sample 2, with a thickness of 0.1 m and a hydraulic conductivityof 1.0 × 10-5 m/s, overlays a 0.2 m sample of soil 1, similar to that described in (1). Once thesystem reaches a steady state, find the water flow velocity in soil 1, as well as the total head at
the boundary between soil 1 and soil 2. Assume, for this problem, that the datum is located at
the bottom of soil 1.

0.1 mSoilsample 2
試料20.1 m

Soilsample 1
試料10.2 mFigure 3(3) Plot the total head, the potential head, and the pressure head distributions of question (2).
Assume that the datum is located at the bottom of soil 1.