PPT 6 Flashcards
_______ is the process of adapting the program to the
unique features of the site.
*It contains proposed plans that are spatially organized on the site.
Conceptual design
Sustainable, context-responsive site
planning has three fundamental
percepts:
- Design with nature
- Design with culture
- Design places for people
Planning for Site Utilities
From site inventory:
- Site Topography
- Hydrology Study
- Soil Investigation
Spatial variation in elevation
produces slopes that have both a
gradient and an orientation.
SITE TOPOGRAPHY
- Types of Soil Protection
o Retaining Walls
o Gabions
o Geotextile
retaining wall
A _______ is a structure built for the purpose of holding back, or
retaining or providing one-side lateral confinement of soil or other
loose materials.
Types of Retaining Walls
Gravity Retaining wall
Semi-gravity Retaining Walls
Cantilever Retaining Walls
Counterfort Walls
Buttress Walls
Other Types
used for walls of up to about 10-12ft in height.
It is usually constructed with plain concrete
and depends completely on its own weight for
stability against sliding and overturning.
Gravity Retaining wall
fall between the gravity and cantilever types.
they depend on their own weights plus the
weight of some soil behind the wall to provide
stability.
Semi-gravity Retaining Walls
- the most common type of retaining wall.
- generally used for heights from about 10-25ft.
- stem: the vertical wall
- toe: the outside part of the footing that is
pressed down into the soil. - heel: the part that tends to be lifted.
Cantilever Retaining Walls
retaining walls with cross walls are behind the
stem (i.e., inside the soil) and not visible.
Counterfort Walls
retaining walls with visible cross walls (i.e., on the toe side).
Buttress Walls
commonly placed at a property boundary or next to an existing building.
- abutments may very well have wing wall extensions on the sides to retain the
soil in the approach area.
- in addition to other loads, abutments will have to support the end reaction
from the bridge.
Other Types
______ are made of wire gabion baskets or cage filled with rocks.
This construction is among the strongest available and used
commercially to stabilize shorelines and riverbanks from erosion.
Gabion walls
__________ are synthetic fabrics
with physical and engineering
properties that are used to
enhance soil properties or to
improve structural performance.
Geotextiles
plastic nets or grids
used for soil reinforcement.
geogrids
impervious
rubber or plastic sheets used for water
or vapor barriers.
geomembranes
a combination
of a fabric, grid, or membrane.
geocomposites
Geotextiles
Applications of Geotextiles
- Separation – geotextiles will prevent two soil layers
of different particle sizes from mixing with each
other, as is illustrated the image below. - Drainage – efficiently collect superfluous water
from structures, such as rainwater or surplus water,
from the soil and discharge it. - Filtration – ideal interface for reverse filtration in
the soil adjacent to the geotextile. The complex
needle-punched structure of the geotextile
enables the retention of fine particles without
reducing the permeability of the drain. - Reinforcement – heavy geotextiles can be used to
reinforce earth structures by means of fill materials.
Its high soil fabric friction coefficient and high
tensile strength is an ideal reinforcement solution. - Protection – geotextiles are an ideal protection
from erosion. A layer of geotextiles can be placed
to prevent leaching of fine material. They can be
used for rock beaching or as mattress structures.
They can even easily be placed under water.
________ is a geosynthetic material, made of polymers, that is used to
reinforce soil behind retaining walls. Installed in horizontal layers
between wall courses and extending into the soil behind a wall,
geogrid stabilizes the soil and so increases a wall system’s mass and
stability.
Geogrid
Understanding the potential impact of floodwater on a site is crucial
to any developer looking to invest in a building scheme or any
planner, engineer or architect acting as an adviser to such
development.
HYDROLOGICAL STUDY
HYDROLOGICAL STUDY
a. Analysis of rainfall – runoff
- hydrological analysis based on
rainfall data in the locality.
b. Delineate Channels and
Waterways - delineate catchment and
identify critical waterways.
c. Evaluate the capacity of
existing drainage - evaluate capacity of road side
drainage to receive flow. - proposed size of drainage.
d. Recommend Flood Control
System - drainage mains (layout and sizes)
- detention pond or lagoon
- recommend finish grade
elevations.
Site planning requires an
understanding of soils and how
they affect hydrology,
construction, erosion control,
and plant growth.
SOIL INVESTIGATION
Implications of soils for Site Construction
a. Earthworks
- excavation for utilities, cut and fill, grading, soil protection, landscaping.
b. Footings and Foundations - the weight of building or structure
is supported by the soil beneath.
c. Drainage Requirements - the relationship between water
and soil needs to be understood for the
management of site drainage to be
successful (including both surface and
subsurface water).
Geotechnical Exploration and Soil
Investigation
a. Land Use Feasibility
- by generally identifying the
portions of a site that are suitable or
unsuitable for development, the
planner can prepare a conceptual site
plan.
b. Site Specific Investigations
- geotechnical explorations are
conducted to identify subsurface
conditions and to gather samples for
laboratory testing when the structural
designer needs data.
c. Critical Conditions
- critical conditions may include
features unique to a particular region,
such as acid soils, limestone sinkholes,
perched groundwater tables, peat
deposits, or organic soil deposits.
Soil Characteristics
a. Soil Phases
- from the geotechnical or
engineering viewpoint, soil may be defined
as an accumulation of solid particles
b. Physical Properties - these properties can include particle
size, shape, and mineralogy, along with
structure, texture, color, organic matter
content, pH, and others.
Soil Classification
a. USDA Textural Classification
System
- first developed to describe soils
for agricultural purposes. - textural designations are based
on three major particle size groups:
sand, stilt, and clay.
b. USCS (ASTM D-2487) - the USCS distinguishes soils based
on their engineering performance as a
construction material, and it considers
texture, gradation, plasticity, and
organic matter content.
c. Grain Size - classification systems
generally describe soil particles as
cobble, gravel, sand, stilt, and clay,
based on size.
Engineering Properties of Soils
a. Bearing Capacity
- bearing capacity is defined as what a soil is able to support per unit area.
b. Shear Strength
- shear strength determines the stability of a soil and its ability to resist failure
under loading
c. Frost Penetration
- in northern climates, silty soils and soils with a wide, fairly evenly distributed
range of particle sizes, referred to as well-graded soils, are subject to frost action.
d. Shrinkage and Swell
- clay soils and soils containing clayey fines tend to shrink as they dry and
expand as moisture content increases.
