TOPIC 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
– are shown on the concept plan.
Major program elements – and important existing conditions
are often portrayed as arrows, and major uses or activity zones are portrayed as polygons, or bubbles.
Circulation pathways
balances human needs (rather than human wants) with the carrying capacity of the natural and cultural environments. It minimizes environmental impacts, and it minimizes importation of goods and energy as well as the generation of waste.
Sustainable design
• Design with nature
• Design with culture
• Design places for people
Context-Sensitive Design
Sustainable, context-responsive site planning has three fundamental percepts:
demands consideration of a diverse set of physical attributes and regulatory constraints.
Responsiveness to site and contextual conditions
•Sun and wind exposure
• Lot size and shape
• Location in relation to transportation systems
• Significant vegetation, topography, and other natural features
• Prominent vistas and views of natural or cultural landmarks
• Building scale and character
These location-specific conditions include the following:
- Site Topography
- Hydrology Study
- Soil Investigation
Planning for Site Utilities
From site inventory:
Spatial variation in elevation produces slopes that have both a gradient and an orientation.
Site topography
must be relatively low to prevent slipping on icy surfaces.
Gradients
would require appropriate soil protection depending on the extent of development goals.
Steep slopes
Retaining Walls
Gabions
Geotextile
Types of Soil Protection
is a structure built for the purpose of holding back, or retaining or providing one-side lateral confinement of soil or other loose materials.
retaining wall
Types of Retaining Walls
- 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.
- It is usually so massive that it is unreinforced.
- Tensile stresses calculated by the working-stress
method are usually kept below 1.6 𝑓 ′ 𝑐.
a. 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.
-are used for approximately the same range of heights as the gravity walls and usually have some light reinforcement.
b. Semi-gravity Retaining Walls
are synthetic fabrics with physical and engineering properties that are used to enhance soil properties or to improve structural performance.
are a subset of geosynthetics
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 will prevent two soil layers of different particle sizes from mixing with each other, as is illustrated the image below.
- Separation –
efficiently collect superfluous water from structures, such as rainwater or surplus water, from the soil and discharge it.
- Drainage –
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.
- Filtration –
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.
- Reinforcement –
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.
- Protection –
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
is carried out to quantify the flow or volume of water in a river or stream, over land, in soils, in a pond or in a reservoir
Hydrological assessment
- delineate catchment and identify critical waterways.
- recommend size of detention basin (if required).
- provide sizing for the drainage mains (drainage trunk)
b. Delineate Channels and Waterways
- evaluate capacity of road side drainage to receive flow.
- proposed size of drainage.
c. Evaluate the capacity of existing drainage
drainage mains (layout and sizes)
- detention pond or lagoon
- recommend finish grade elevations
d. Recommend Flood Control System
• Site planning requires an understanding of ____ and how they affect hydrology, construction, erosion control, and plant growth.
•____ affects the design of stormwater management facilities.
• ____ engineering properties can greatly affect grading activities, depending on physical parameters such as texture, gradation, and water content.
• ____ also serves as a foundation material, providing support for buildings and other structures.
3.) SOIL INVESTIGATION
- excavation for utilities, cut and fill, grading, soil protection, landscaping.
- where retaining walls are necessary, their design will be based on the engineering properties of the soil and on the presence or absence of additional groundwater or pore water pressures.
- fill operations, including the method of soil placement and the type of compaction equipment, are specified according to the soil types to be handled.
- soil conditions are also evaluated in determining the need for bracing or shoring of temporary excavations. Implications of soils for Site Construction
a. Earthworks
- the weight of building or structure is supported by the soil beneath.
- the design of a footing depends on the applied load and the nature of the underlying soil.
- type of foundation (shallow or deep) are determined by the soil properties.
b. Footings and Foundations
- 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).
c. Drainage Requirements
: non-cohesive soils tend to be more erodible, more permeable, and easier to drain.
sandy
: soils tend to be more erosion resistant, less permeable, and more difficult to drain.
- clayey
: that are composed of layers of both coarse-and fine grained soils may present complex conditions that need to be evaluated in site design.
satisfied soils
Geotechnical Exploration and Soil Investigation
- by generally identifying the portions of a site that are suitable or unsuitable for development, the planner can prepare a conceptual site plan.
a. Land Use Feasibility
geotechnical explorations are conducted to identify subsurface conditions and to gather samples for laboratory testing when the structural designer needs data.
b. Site Specific Investigations -
- 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.
c. Critical Conditions
from the geotechnical or engineering viewpoint, soil may be defined as an accumulation of solid particles generated from the physical and chemical weathering of parent rock. - soil, therefore, contains three phases: solids, water, and air.
a. Soil Phases -
- these properties can include particle size, shape, and mineralogy, along with structure, texture, color, organic matter content, pH, and others. - physical properties such as density, moisture content, and specific gravity provide useful information to geotechnical experts and reveal how the soil will behave or perform as a construction material.
b. . Physical Properties
Soil Classification
first developed to describe soils for agricultural purposes. - textural designations are based on three major particle size groups: sand, stilt, and clay.
a. USDA Textural Classification System -
- classification systems generally describe soil particles as cobble, gravel, sand, stilt, and clay, based on size.
b. Grain Size
the USCS distinguishes soils based on their engineering performance as a construction material, and it considers texture, gradation, plasticity, and organic matter content.
c. USCS (ASTM D-2487) -
-is defined as what
a soil is able to support per unit area.
- if the ___of an existing soil cannot support the proposed load or structure, the soil must be moved and replaced with a suitable material or other engineering measures must be taken.
a. Bearing Capacity
-determines the stability of a soil and its ability to resist failure under loading.
- is the result of internal friction and cohesion.
- internal friction is the resistance to sliding between soil particles, and cohesion is the mutual attraction
between particles due to moisture content and molecular forces.
b. Shear Strength
- 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.
- damage to structures and roads due to frost action is caused by the movement of soil as it freezes and the loss bearing capacity as it thaws.
c. Frost Penetration
– clay soils and soils containing clayey fines tend to shrink as they dry and expand as moisture content increases.
- the degree of volume change will depend on the mineralogy of the clay particles and the degree of moisture change.
- highly plastic clays with very fine, or colloidal, particles that exhibit significant volume change are termed expansive clays.
b. Shrinkage and Swell
