For a soil element located at a depth, z = 5 m underneath the ground surface, determine the vertical effective stress if:

the soil saturated unit weight, gsat = 20 kN/m3
the water table is located at the ground surface
Ko = 0.5

Hint: take unit weight of water gw = 10 kN/m3

Question

For a soil element located at a depth, z = 5 m underneath the ground surface, determine the vertical effective stress if:

the soil saturated unit weight, gsat = 20 kN/m3
the water table is located at the ground surface
Ko = 0.5

Hint: take unit weight of water gw  = 10 kN/m3

BlackTom AI · Accepted Answer

Let me restate the problem to ensure clarity: a soil element is at depth z = 5 m below ground surface with saturated unit weight gsat = 20 kN/m3, a water table at the ground surface, Ko = 0.5, and the water unit weight gw = 10 kN/m3. We are to determine the vertical effective stress at that depth.

First, compute the total vertical stress at depth z. Since the soil is saturated up to depth and the vertical stress is carried by the saturated soil, the total vertical stress is proportional to the saturated unit weight: sigma_v = gamma_sat * z = 20 kN/m3 * 5 m = 100 kPa.

Next, determine the pore water pressure at that depth. With the water table at the ground surface (z = 0 at surface) and gw = 10 kN/m3, the pore water pressure increases linearly with depth: u = gamma_w * z = 10 kN/m3 * 5 m = 50 kPa.

Now, obtain the vertical effective stress using the effective stress principle: sigma_v' = sigma_v - u. Substituting the values gives sigma_v' = 100 kPa - 50 kPa = 50 kPa.

A few notes on potential confusion:
- Ko (the coefficient of earth pressure at rest) affects lateral stresses, not directly the vertical effective stress in this straightforward vertical loading scenario. Since the problem asks for vertical effective stress at depth, Ko is not required for this calculation.
- If one mistakenly used gamma = gsat as the driving weight for effective stress without accounting for pore pressure, they would get an incorrect result; the pore water pressure must be subtracted to obtain the effective stress.
- If the water table were deeper, or if the soil were unsaturated, the pore water pressure and thus the calculation would differ. Here, with the water table at the surface and full saturation, the pore pressure equals gw * z as used.

Therefore, the vertical effective stress at z = 5 m is 50 kPa.

ENEN20002_2025_SM1 Quiz on Lecture 32 material

For a soil element located at a depth, z = 5 m underneath the ground surface, determine the vertical effective stress if: the soil saturated unit weight, gsat = 20 kN/m3 the water table is located at the ground surface Ko = 0.5 Hint: take unit weight of water gw = 10 kN/m3

查看解析

登录即可查看完整答案

类似问题

When you apply a load on ground, there will be a stress field develops in the soil underneath the ground. The effective stress in this stress field means;

In a consumer society, many adults channel creativity into buying things

Economic stress and unpredictable times have resulted in a booming industry for self-help products

People born without creativity never can develop it

A product has a selling price of $20, a contribution margin ratio of 40% and fixed cost of $120,000. To make a profit of $30,000. The number of units that must be sold is: Type the number without $ and a comma. Eg: 20000

Which of the following statement regarding cost is correct:

Under the assumptions used in cost-volume-profit analysis, as the activity increases:

更多留学生实用工具

考试浏览器助手

风格化写作助手

论文查重助手

文献引用助手

课堂转译助手

课堂笔记助手

Quiz搜索助手

学校历年真题

智能刷题助手

智能匹配练习

希望你的学习变得更简单