DIMENSIONS IN THE MODEL SPACE WON'T SHOW UP IN LAYOUT IN AUTO CAD 2010

I'm using Auto Cad 2010 and was confused to find out model space dimensions(annotative) are not visible in the layout.
There was no particular problem with layers,scale etc.
At least i got it and thought it'll help you as well.It is just a matter of a button at the bottom right hand corner.(Highlighted)Annotative dimensions are not shown unless the button is turned on.

Click on the 'trillium button with a light bulb'. 
This will turn objects from all scales on or off.
you can also type  "ANNOALLVISIBLE" in the command prompt.

Deep Cement Mixing

The Deep Cement Mixing method is based on chemical reactions between clay and chemical agent,which is usually ordinary Portland cement.This is done by machines with rotating blades for supplying the chemical agent in to the soil and for insitu mechanical mixing of the soil with the agent.The chemical agent absorbs the pore water and reacts with clay particles to form pozzolanic products.

 A typical deep cement mixing machine consists of one or two rotating shafts with excavation blades and mixing blades driven by hydraulic or electric motor.Dual shaft system is commonly used to ensure uniform mixing and provide large excavation capacity.

After the required quantity of hardening agent is determined and excavation conditions such as penetration and withdrawal rates are confirmed by trial mixing works and laboratory testing,production ground stabilization work is taken up.The mixing machine,usually installed on track mounted rigs, will be mobilized to the specified location and the following construction sequences will be carried out to form a soil cement column in soft ground.

 1.Mixing shaft will rotate and penetrate in to the soft soil to the designed treatment depth.
2.While penetrating in to the ground,cement slurry will be injected and mixed with soft soils
3.After reaching the founding level of the soil cement column,the mixing shaft will be withdrawn.
4.While withdrawing the mixing shaft,the cement slurry and the soft soil will be mixed again to ensure uniform soil-cement mix
5.A soil -cement column is then formed and the above construction sequences will be repeated at the next location.

Gabion Retaining Walls - Check List

Gabions are a type of gravity retaining walls in Civil Engineering context.They are made of  rectangular containers fabricated in  thick galvanized wire which are filled with stones and stacked on one another.

They are mainly used in situations where we cannot use RRM (Random Rubble Masonry ) retaining walls to address unstable ground conditions.River embankments,marshy lands,culvert approaches are such situations.

In this post i wish to discuss what are the key points that we should pay attention to maintain the quality during construction.

Use cages depending on the site conditions.
Gabions come as coated and non coated galvanized cages.You have to chose between the two according to the site conditions.For an instant if we are constructing gabions in a coastal area coated cages are the best match.

Use a Geo-Textile layer covering the  embankment face.
Excavate at least 400mm from the original ground level
Pack the boxes do not fill.
Incline the walls 6 degrees towards the embankment face.
Tie the cages firmly to each other.
Do not use stones smaller then gabion net size.
If it's a river bank excavate 2ft below the river bed level.

Basic setting out of a building

This is the process of obtaining the positions of the structural parts of a building in the geometrical construction. The positions of the structural parts of a building can be obtained by detailed structural drawings. These data has to be transferred to the field to start the geometrical construction with sufficient accuracy; enabling independent checks for readily detecting of any errors.

setting out ....from drawing's to reality

The first step in building setting out is to identify a base line according to the site layout plan. We can establish the base line considering the permanent structures and the relevant distances to structural parts from them as given in the drawings.

Step 1: Obtaining of a Base Line

Step 1: Obtaining of a Base Line

Setting out is done based on the principle of “Whole to part”. According to this principle the largest possible rectangle of the building is found and set up first. Then it is further divided into small parts completing the major setting out for the building.

It is very important that setting out process is done in a horizontal plane. When the ground profile is not horizontal proper care must be paid to establish the setting out profiles in a one level. For simple applications a tube filled with water can be used to obtain the levels.

Main instruments involved in this process are Theodolite, Steel and Linen Tapes, Arrows, Wooden pegs, Wire nails and Nylon threads.

 

Theodolite and Wooden Pegs used for Setting Out  

After establishing the base line, the main rectangle is set up using the pegs and theodolite. Arrows are used as temporary pegs and wooden pegs are driven for permanent pegs .90° angle is taken by the theodolite and Pythagoras rule is also commonly used for the process. When using the Pythagoras rule proper care must be paid to obtain the largest possible combination of triangles for higher accuracy. Steel tape must be used to measure long distances and it must be tightly stretched when taking the readings.

Wooden pegs atop by a wire nail are driven to establish the grid lines of the building. These pegs are driven at places such that they won’t be disturbed by field work etc. Usually they are driven with a distance of 1.5 meter from the grid line.

The diagonals of the main rectangle are checked to determine its accuracy. Accurately set up main rectangle is then subdivided to obtain the consisting gridlines. These are obtained by the using structural drawings, Theodolite and steel tape. Nylon threads are stretched between the pegs to obtain the gridlines when necessary.

Usually apart from the pegs depicting the main grid lines, pegs which show the 500mm off sets are also established during the setting out process to facilitate the construction that follows.

Improvement for a Soft Subgrade in a Railway Track

This is a brief description on how to improve a soft subgrade in a railway track.

This portion of the track is a cut through a small mountain with sharp soil embankments in both sides of the track .Existing soil is of a sandy clay type and there was no proper drainage system to drain out the water which gets accumulated owing to the soil embankments.The track has suffered rapid settlements and constant ballast creep.

                                   

The first step in improving this soft subgrade was to cut two deep drains on either side of the mountain embankments to drain out the accumulated water ,making the surface dry  for machine movements.

Step two was to provide a geo -grid to arrest the ballast creep along with a 200mm layer of Aggregate Base Course (ABC).

Ultrasonic pulse velocity (USPV) Test - Compressive strength of Concrete

 
Ultrasonic test for concrete is a field test for quality control and inspection of concrete structures. It uses measurement of the speed of ultrasonic pulses through the concrete to correlate concrete strength to standard strength. Using this test we can identify non-homogeneous conditions in the structure such as honeycombs, voids, cracks and frozen concrete.

First the instrument is calibrated using a standard calibration bar and the receiving and the transmitting ends are coated with a thin uniform grease layer. The concrete surface is cleaned well to make it dust free and uniformly distributed grease layer is applied on the concrete surface as well. The transmitting and receiving ends of the apparatus is then placed on marked locations of the structure and the machine is turned on to get the reading. The test is repeated after switching the positions of the transmitting and receiving ends. Then obtained readings are compared with the standard values to arrive at a conclusion about the concrete quality.

The use of the teat is covered by BS 4408: part 5

Destressing of Rails

Rails are made out of steel and are exposed to natural environment  through out  its life time in the railway track.This means rails get exposed to diffrent temperatures during the day and night.As we all know metal gets elongated when exposed to high temperature and gets contracted in the case of clod temperature.Due to this reason compressive and tensile forces get developed in the rails as they are fixed to the sleepers restricting their free movement with the themperature.There is a temperature where there is no forces in the rail and its called rail nutral temperature.If we can fix the rail and maintain it at this nutral temperature there will be no stresses on the rail and it will be ideal condition for the track.Practically this is out of reach and we can only minimize the tensile and compressive forces in the rails by laying it at a mean temperature.
Rails in Hot Weather

In hot weather conditions compressive stresses develop in the rails and as a result they get buckled.

Rails in Cold Weather
In cold weather conditions tensile stresses develop in the rails and as a result they get break. 

Buckling of rails and rail Break are two major reasons for derailing of rails.

The purpose of destressing is to avoid above two sinarios and provide a safer track for train movement.Destressing  for Hot weather and Cold Weather is done separately during two periods of the year.Part of the rail is cut and weld in hot weather case whereas a new peice is add and weld in the cold weather case.

Mean Temperature and Temperature Range for Destressing In Hot Weather.
To determine this mean temperature a detailed servey is required where we have to record rail temperature with time .Mean temerature depends on country to country and from region to region. With this data we can obtain the minimum and maximum rail temperatures and hence the mean rail temperature.In a tropical country this mean value is around 37C .We get the temperature range by adding 5 units to the higher side which is 37+5 = 42C.Here the plus side is preferd as it resembles tension in the rails which  avoids buckling.

Destressing at Site

In simple words we have to

remove the rail from elastick clips 

alllow its free movement with the tempertaure 

and fix it back

within the given temperature range .