REPORT ON ADVANCED GEOTECHNICAL
ENGINEERING
Topic:
Relations between geotechnical and
hydraulic engineering
Prepared
for Prof TOYOTA Hirofumi,
Nagaoka University of Technology
Prepared
by Ayurzana Badarch, 14701491
10 January 2015
Инженерчлэл гэдэг нь шинжлэх ухааны мэдлэгийг ашиглан хүмүүний нийгэм, эдийн засаг эсвэл байгалийн тэнцвэрт байдалд зориулан бүтээж буй биетлэг оюунлаг үйл ажиллагааг хэлнэ. Чөлөөт нэвтэрхий толь - Engineering. Инженерчлэл хийхэд мэргэшсэн хүнийг инженер хэмээнэ.
Энэхүү тайланд усны инженерчлэл болон геотехникийн инженерчлэл хоорондын уялдаа хамаарлын тухай уншиж судалсан, мэдэрсэн, бодсон зүйлээ бичсэн юм. Геотехникийн инженерчлэлийг зөвхөн барилгын буурь суурийн бат бэх, тогтворшилт хэмээн ойлгох нь эндүүрэл бөгөөд энэ талын мэргэжлийн инженер нь тал бүрийн барилга байгууламжийн талаар ерөнхий мэдлэгтэй байхаас гадна усны тэр дундаа гидравликийн тухай нарийн ойлголттой байх хэрэгтэй юм. Геотехникийн суурь шинжлэх ухаан нь хөрсний механик юм. Барилгын бүтээцийн инженер геотехникээр мэргэших нь өрөөсгөл асуудал гэж ойлгож байна.
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Introduction
This report is providing that
relationship between geotechnical engineering and hydraulic engineering. In
this report, also I stated that main distinguish between research fields of
geotechnical and hydraulic engineering, which are defined and expressed my
thought. In order to describe relations between geotechnical and hydraulic
engineering, some practical example is assorted in this report that is mainly
related to Mongolian field. Mongolia is currently developing country.
Especially science and engineering approach, is changed after revolution of
1990, has been pursuing to international achievement. Similarly, civil
engineering education and activities in social environment have been come up to
international approach. One of good instance is building code switching from
Russian to Euro code in legal environment of civil engineering. Despite this
development, some various understanding and concept related to distinguish of
engineering still exist in hydraulic and geotechnical engineering field. This
is outlined at least part of this report.
In the civil engineering field, many
investigation and decision can be achieved when geotechnical and hydraulic
expertise or engineers are strongly interlinked. This interlinked communication
shows main key aspect of their relations which can be expressed that sharing
knowledge and experience of their own research field.
Hydraulic engineering
Before any project related to water and hydraulics can be constructed, a number of technical and semi-technical questions must be answered. For example how much water is involved? How will interact water with building matter such as solid wall or foundation? Therefore some specific engineering knowledge is needed for achieving hydraulic projects. Hydraulic engineering as the application of fluid mechanics principles to problems dealing with the collection, storage, control, transport, regulation, measurement, and use of water. Hydraulic engineering encompasses a broad portion of field of civil engineering (Prasuhn, 1992) and concerning about water resource management and monitoring. Hydraulic engineering also lends solid mechanics principle since fluid is interacted with solid or flowing through porous medium. Likewise, saturated soil behavior and its circumstantial physical concept are described by using both cognitions of geotechnical and hydraulics.
Geotechnical
engineering
Before discuss relation between
geotechnical and hydraulic engineering, general description should be made what
is object of those engineering. Every structure is constructed on the ground
which is formed by soil characteristics. Thus, civil engineers must study the
properties of soil, such as its origin, grain size distribution, ability to
drain water, compressibility, shear strength, and load-bearing capacity while
knowing building material properties. This leads to geotechnical engineering.
A geotechnical engineer then determines and designs the type of foundations,
earthworks, and pavement subgrades required for the intended man-made
structures to be built. Foundations are designed and constructed for structures
of various sizes such as high-rise buildings, bridges, dams, medium to large
commercial buildings, and smaller structures where the soil conditions do not
allow code-based design. By classical definition, geotechnical
engineering is the sub-discipline of civil engineering that involves natural
materials found close to the surface of the earth. It includes the application of
the principles of soil mechanics and rock mechanics to the design of
foundations, retaining structures, and earth structures (Braja, 2006) . Thus Geotechnical
engineering object covers the soil including all properties for physical,
mechanical and chemical.
Relations based on
object
Object means that research thing as a soil for geotechnical
and water for hydraulics. It can be also called problem based relations since
problem depends on both of soil mechanics and fluid mechanics. Let’s assume
soil consolidation process. If soil, saturated with water, is loaded by
constructing a building on top of soil, a deformation can occur, even if water
and soil grains are considered incompressible. The reason is that grains can
move relative to one another, such that the pore volume changes. The water in
the pores has to flow in or out from pore, which takes some time. This
consolidation process is time dependent. In this problem, pore water movement
or flow is operated by local pressure gradient of Darcy law, while grains total
normal stress is simplicity can be governed by elastic material concept that
Hooke’s law (Vreugdenhil, 1989) . In order to
determine relative volume change of soil that consequence of consolidation
process, you need to solve pressure from standard diffusion equation derived
from above mentioned two laws. As view point of geotechnical engineering, you
need to concern hydraulic concept such that Darcy law’s and how to solve
diffusion equation etc. In contrary sight of hydraulic engineering, you need to
know mechanical properties of system of soil grains which is a quite
complicated subject. Once problem uses object (soil and water) of these two
disciplines, there must have collaboration of geotechnical and hydraulic
engineers. This is simple case for relations based on objects.
It is clear that soil mechanic can be divided unsaturated
and saturated soil mechanics. Above assumed soil consolidation problem dials
with saturated soil mechanics which concerns two phase. In unsaturated soil, it
requires more than two phase behavior. Simplified description of soil
mechanical strength is structure via bulk density, hydraulic stress via water
content and mechanical stress via external stress. In order to describe the
physical processes acting on soil mechanical strength for soil compaction or
slope stability, it is needed to study the interaction between hydraulic,
mechanics and structure in unsaturated soils. These interactions have been
studied and modeled for several decades using the concept of effective stress
and the theory of critical-state for geotechnical applications (Fredlund
& Rihardjo, 1993) . In order to understand unsaturated
soil behavior, object is soil, water, and air then hydraulically subject may
cover widely of fluid mechanics such as flow laws, measurement of permeability,
capillarity and steady state flow concepts. Unlike those challenge with good
relations developed in other countries, there is quite silent in Mongolia.
Generally, geotechnical is restricted only foundations of building according limit
state design (just elasticity soil) excepting permafrost geotechnical study and
light clayey soil behavior (Dashjamts, 2011) . This is fact that
relation is not higher between Mongolian geotechnical and hydraulics
engineering.
Relations based on Knowledge
Above mentioned problems would not have
been perfect studied without contributing their knowledge and sharing
achievement. This is impossible to understand unsaturated soil behavior without
knowing capillarity. This delicacy, achievement and concept of those
sub-disciplines use to solve mixed problems and directly applied practice,
shows that significantly relations between hydraulics and geotechnical
engineering. Their relations no longer exist both, also connected with other
sub-discipline due to its theoretical foundation (Katzenbach,
Schmitt, & Turek, 2003) .
Hydrostatic pressure expression
is
used to calculate vertical stress on the point for soil mechanics and also its
form used to Rankine theory assuming pressure coefficient for active and
passive lateral pressure. This is good example for relation based on knowledge
of geotechnical and hydraulic engineering. This kind of sharing relation can be
described by concerned function depended parameters are similar for soil and
water or assuming equivalent homogeneous medium.
Nowadays numerical approach is commonly
developed in engineering field. In this case introduced methodology or scheme
in hydraulic field can be used or modified geotechnical problems or vise versa.
Some of discovery (in geotechnical) can be way to improve one step for another
(hydraulic). For example, if we know how to accurately model ice formation
process in hydraulic field, it will lead to simplicity understanding rising of
soil under road which is main problem of Mongolian road. There are relations
based on sharing achievement between geotechnical and hydraulic engineering.
Distinguish between
hydraulic and geotechnical engineering
Once we have airily discussion about
relations between hydraulic and geotechnical engineering, we cannot omit their
difference or indistinguishable problems.
Note that this argument based on Mongolian approach, not a cover all of world. Obviously,
difference between this two engineering is big, but some analogous problem exist both
field. One of them can be seepage. In seepage through dam or seepage under dam
problem, not contribute is concerned from geotechnical engineer, since soil is
uniform or isotropic. In this case, certain number of soil behavior is needed
to solve factor of safety which is refined by ratio of the critical gradient (Ic)
to the predicted or measured exit gradient (Ie) (Engomoen,
2014) .
This tendency has been dominated as long year in Mongolia and some other
specific country. Therefore
many small irrigation earth dam collapsed last time, reason is seepage of under
dam in Mongolia. Assuming soil is non uniform (anisotropy) and accurately
design or model of internal erosion and suffusion are concerned in account of
seepage, and changing tendency for engineering collaborating environment, some
advance will appear. In social that science and information technology is
widely developed, there is no one who knows everything about soil or water.
Therefore, contribution and collaboration between engineers, scientist and
specialist is important for better resulted investigation.
Works Cited
Braja, M. D. (2006). Principle of geotechnical
engineering, fifth edition. Sacramento: Tompson.
Dashjamts, D. (2011). Structurally unstable soil
mechanics and Foundation engineering problems. Ulaanbaatar: Admon press.
Engomoen, P. (2014). Standard design №13 for
Embankment dam. Washington DC: Bureau of Reclamation.
Fredlund, D., & Rihardjo, H. (1993). Soil
mechanics for unsaturated soil. New York: Jons Wiley and Sons.
Katzenbach, R., Schmitt, A., & Turek, J. (2003). Interaction
between Structural and Geotechnical Engineers. London: Thomas Telford Ltd.
Prasuhn, A. (1992). Fundamentals of Hydraulic
engineering. Brookings: Oxford university press.
Vreugdenhil, C. (1989). Computational hydraulics.
Heidelberg: Springer.
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