Theodolite Traversing on survey and procedure

Theodolite Traversing on survey and procedure: 

What is Theodolite? Theodolite is used to measure the horizontal and vertical Angeles, It is recommended for more precise magnetic compass, This magnetic compass will help in measuring the angle up to an accuracy of 30, Along with this there is another tool which will measure the angle accuracy to 10, 20 using vernier theodolite. There are many theodolite types of the vernier, optic, electronic etc. Vernier theodolite is known as transmit, This transit theodolite has a telescope which can be rotated in a vertical plane.

Theodolite Traversing on survey and procedure:

Main parts involved in this theodolite are Levelling head and it is used to attach the instrument to a tripod and it will attach the plumb bob fixed along the vertical axis of the instrument. Main parts involved in this item are an (18): an annular horizontal plate with the graduations provided all around, from 0 to 360°, in a clockwise direction. The graduations are in degree divided into 3 parts so that each division equals to 20 min. Main things to remember are when the verticle circle of the theodolite is on right side of the observer, this position is named as face right and observation made is called face right observation.

Theodolite Traversing on survey and procedure

Depending upon the position you kept there are different terminology to use like Face Left, Telescope Normal, Telescope Inverted. while setting the instrument you need to be careful on maintaining the levelling, Focussing will mean a lot as well, Focussing the eyepiece, Focussing the objective, depends on two methods Repetition method and Reiteration method.

Errors you will come across while setting up this Theodolite Instrument are:

• Non-adjustment of plate bubble
• Line of collimation not being perpendicular to horizontal axis
• Horizontal axis not being perpendicular to vertical axis
• Line of collimation not being parallel to axis of telescope
• Eccentricity of inner and outer axes
• Graduation not being uniform
• Verniers being eccentric
• Personal errors
• Natural errors
• High temperature causes error due to irregular refraction.
• High winds cause vibration in the instrument, and this may lead to
• wrong readings on verniers

There are two types of Surveying in Civil Engineering like:

• Closed Traverse
• Open Traverse

Methods involved in Traversing are:

• Chain traversing 
• Chain and compass traversing 
• Transit type traversing a)By fast needle method b)By measurement of angles between the lines
• Plane table traversing

Field Techniques Manual GIS, GPS and Remote Sensing

Field Techniques Manual : GPS, GIS and Remote Sensing

Definition of GPS:
The Global Positioning System (GPS) is a technical marvel made possible by a group of satellites in earth orbit that transmit precise signals, allowing GPS receivers to calculate and display accurate location, speed, and time information to the user.
GPS was originally created by the United States Department of Defense (DOD) as a military application. 

 GPS signals may be blocked by dense forest, canyon walls, or skyscrapers, and they don’t penetrate indoor spaces well, so some locations may not permit accurate GPS navigation.

While the U.S. owned and operated GPS is currently the only active system, five other satellite-based global navigation systems are being developed by individual nations.

Definition of GIS:
A geographic information system (GIS) integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information on the monitor or the display.

Definition of remote sensing:
The scanning of the earth by satellite or high-flying aircraft in order to obtain information about it.

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Geotechnical Engineering Laboratory Manual pdf

Definition:
Geotechnical engineering is the branch of civil engineering concerned with the engineering behavior of earth materials.
Branch of civil engineering :

History:

Several foundation-related engineering problems, such as the Leaning Tower of Pisa, prompted scientists to begin taking a more scientific-based approach to examining the subsurface. The earliest advances occurred in the development of earth pressure theories for the construction of retaining walls. Henri Gautier, a French Royal Engineer, recognized the "natural slope" of different soils in 1717, an idea later known as the soil's Angle of  repose. A rudimentary soil classification system was also developed based on a material's unit weight, which is no longer considered a good indication of soil type.

In geotechnical engineering, soils are considered a three-phase material composed of: rock or minerals particles, water and air. The voids of a soil, the spaces in between mineral particles, contain the water and air.

The engineering properties of soils are affected by four main factors: the predominant size of the mineral particles, the type of mineral particles, the grain size distribution, and the relative quantities of mineral, water and air present in the soil matrix. Fine particles (fines) are defined as particles less than 0.075 mm in diameter.

Soil properties

Some of the important properties of soils that are used by geotechnical engineers to analyze site conditions and design earthworks, retaining structures, and foundations are:
Unit Weight
Total unit weight: Cumulative weight of the solid particles, water and air in the material per unit volume. Note that the air phase is often assumed to be weightless.
Porosity
Ratio of the volume of voids (containing air, water, or other fluids) in a soil to the total volume of the soil. A porosity of 0 implies that there are no voids in the soil.
Void ratio
is the ratio of the volume of voids to the volume of solid particles in a soil. Void ratio is mathematically related to the porosity.
Permeability
A measure of the ability of water to flow through the soil, expressed in units of velocity.
Compressibility
The rate of change of volume with effective stress. If the pores are filled with water, then the water must be squeezed out of the pores to allow volumetric compression of the soil; this process is called consolidation.
Shear strength
The shear stress that will cause shear failure.
Atterberg Limits
Liquid limit, plastic limit, and shrinkage limit. These indices are used for estimation of other engineering properties and for soil classification.

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