0.20 Water is pumped from an aquifer, as shown in Figure P9.20, for domestic use. The original groundwater level was at the top of the soft clay and dropped by 10 m. The ground surface subsided. (a) Assuming that the subsidence is due to the settle- ment of the soft clay, estimate the settlement of the ground surface. (b) A decision was made to recharge the aquifer by pumping water from a canal. If the groundwater level were to return to its original level, would the ground surface return to its original elevation? If so, why? If not, why not? Show calculations to support your answer. How much recovery (expan- sion of soil) is possible using the one-dimensional consolidation theory? Original ground surface elevation Lightly cemented (calcium carbonate) sand/gravel : = 17 kN/m3 Clay properties: w = 55% C = 0.4 C, = 0.05 C, = 0.04 m²/yr k̟ = 1 x 106 cm/s k = 5 x 106 cm/s OCR = 1 20 m sat Original groundwater level Soft clay- 5 m :Aquiferºº Sand and gravel. 10% 15 m W = Rock FIGURE P9.20

0.20 Water is pumped from an aquifer, as shown in Figure P9.20, for domestic use. The original groundwater level was at the top of the soft clay and dropped by 10 m. The ground surface subsided. (a) Assuming that the subsidence is due to the settle- ment of the soft clay, estimate the settlement of the ground surface. (b) A decision was made to recharge the aquifer by pumping water from a canal. If the groundwater level were to return to its original level, would the ground surface return to its original elevation? If so, why? If not, why not? Show calculations to support your answer. How much recovery (expan- sion of soil) is possible using the one-dimensional consolidation theory? Original ground surface elevation Lightly cemented (calcium carbonate) sand/gravel : = 17 kN/m3 Clay properties: w = 55% C = 0.4 C, = 0.05 C, = 0.04 m²/yr k̟ = 1 x 106 cm/s k = 5 x 106 cm/s OCR = 1 20 m sat Original groundwater level Soft clay- 5 m :Aquiferºº Sand and gravel. 10% 15 m W = Rock FIGURE P9.20

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

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Concept explainers

Groundwater Flow

The term groundwater refers to the water which is found beneath the earth's surface. Pores present in the soil and rocks with fractures make a passage for rainwater to enter the earth's surface and deposit as groundwater. The flow nature and direction of groundwater under the earth's surface directly impacts the strength and compressibility of the soil, which reflects its ability to support structural loads.

Question

9.20 Water is pumped from an aquifer, as shown in Figure P9.20,
for domestic use. The original groundwater level was at
the top of the soft clay and dropped by 10 m. The ground
surface subsided.
(a) Assuming that the subsidence is due to the settle-
ment of the soft clay, estimate the settlement of the
ground surface.
(b) A decision was made to recharge the aquifer by
pumping water from a canal. If the groundwater
level were to return to its original level, would the
ground surface return to its original elevation? If
so, why? If not, why not? Show calculations to
support your answer. How much recovery (expan-
sion of soil) is possible using the one-dimensional
consolidation theory?
Original ground
ace elevation
Lightly cemented (calcium
carbonate) sand/gravel
17 kN/m3
Original groundwater level
Soft clay
20 m
Clay properties:
w = 55%
C_ = 0.4
C, = 0.05
C, = 0.04 m2/yr
k = 1 x 10-6 cm/s
k = 5 x 10-6 cm/s
OCR = 1
sat
5 m
%3D
Aquifer
Sand and gravel
w = 10%.
15 m
Rock
FIGURE P9.20

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