Friday, October 15, 2010

Chile Celebrates As Miners Emerge from Underground


By the time the capsule rose through the mineshaft's manhole-size opening shortly after midnight, the surrounding desert outside the northern Chilean city of Copiapó was as dark and cold as a sepulcher. But when 30-year-old Florencio Avalos emerged from 2,000 ft. (700 m) below the earth — where he and his 32 companions had been huddled since their gold and copper mine collapsed on Aug. 5 — and into the arms of his wife and children, an incandescent fiesta of life erupted on the surrounding dunes and rock piles. Men who had been all but buried alive for 69 days had just become the world's newest heroes.

The U.S. exulted 40 years ago when it brought its three Apollo 13 astronauts back safely from a disaster in space. Early Wednesday morning, Chile — and, for that matter, Latin America, a continent whose achievements are so often overshadowed by natural and political tragedy – can celebrate its own finest hour as it rescues its 33 miners from the abyss. Chileans, not known for exuberance, unleashed deafening cheers and chants through the chilly air above the San José mine — "Tonight we bring them back!" — along with confetti and balloons bearing the Chilean flag. The sight of Avalos' 7-year-old son, wearing a hard hat alongside Chilean President Sebastián Piñera as he awaited his father, brought many at the mine, now known as Camp Hope, to tears. "We made a promise to never surrender, and we kept it," said Piñera, who arrived at the site on Tuesday and earlier said that the miners' rescue would be "a true rebirth for us all." 

It will be a prolonged one as well. The process of sending the 21-inch-wide (50 cm wide) capsule down the almost half-mile diagonal duct and then carrying each miner up to the surface will take as much as an hour or more. As a result, officials said they expected Operation San Lorenzo — named for the patron saint of miners — to last about 48 hours. Twenty-three of the 33 miners have been rescued. Said the second, Mario Sepúlveda: "I think I had extraordinary luck. I was with God and with the devil. And I reached out for God."

The operation was made possible last Saturday when a giant U.S.-operated drill finally bored through the ceiling of the miners' 538-sq.-ft. (50 sq m) emergency shelter, a good month before most had expected. Since then, the men prepared for their rides up in the specially designed Phoenix capsule. They did squats and other leg-strengthening exercises to keep their blood circulation even for the 15-minute ascent; they ate only protein supplements and carbohydrates to avoid nausea. See TIME's top 10 miraculous rescues.)

Officials, doctors and psychologists who had been monitoring the miners throughout the more than two-month ordeal — a survival record in the annals of mining disasters — drew up an order of ascent. "Los más hábiles" — a half-dozen of "the most able," like Avalos — would go first, since they could better handle any problems on the way up that rescue workers could then fix for the others going after them. The weaker members of the group would follow, and then the stronger.

Each would wear a special helmet equipped with communications gear so officials could keep in constant contact with them; an oxygen mask and a belt with vital-signs sensors around the torso; and dark glasses to keep their eyes, more like those of moles now than of humans, from being damaged in the sudden return to light. Liliana Gómez, the wife of the oldest of the men, Mario Gómez, 63, who has silicosis, a lung ailment common among miners, hoped that he would be carrying his inhaler. "He'll be much less nervous if he does," she told TIME. "I'll be much less nervous if he does." 

Indeed, claustrophobic panic attacks during the ascent have been the one key concern, and officials are ready to increase the lift speed to 10 ft. (3 m) per second should a miner have one. "Every rescue has risks," said Mining Minister Laurence Golborne before the operation, "but we've got hundreds of different contingencies in place." Many had assumed the miners would be given anxiety-reducing drugs before the lift; but medical advisers insisted the men be in a natural state, "not all drugged up, so they'll be alert to whatever problem they might encounter on the way up," Dr. Franco Utili, an emergency medical specialist on the rescue team, told TIME.

So far, the only nervous moment has been a three-hour delay in the operation's start, when Golborne reported a problem with the capsule door during testing Tuesday night. When the damage (which could have caused the capsule to get caught on the wall of the 28-inch-wide [70 cm wide] shaft) was fixed, the first of a handful of rescue workers was lowered down shortly after 11 p.m. to gauge the miners' condition and assist them with the capsule. Within minutes Avalos, the No. 2 leader of the mining group who had been charged with video-monitoring his comrades' subterranean health for officials above, was on his way. After he arrived at the bottom, another rescue worker was sent down, and another miner was sent up: the electrician-prankster Sepúlveda, 39, who lightened the moment by giving Piñera and his attending Cabinet ministers joke gifts of rocks from the mine below and then led them in rowdy cheerleader chants.

Each man, who was allowed to have about three family members greet him as he popped through the hole, was to be examined by doctors at a makeshift medical facility at the rescue site. Then they would be whisked by air force helicopter to a hospital in Copiapó for a minimum of two days' observation. The last miner up will be Luis Urzúa, 52, the shift foreman who was the men's leader and kept them cohesive during their entrapment — a role officials want him to play throughout the rescue phase as well. 

But even if they get a physical pass, they'll need months, if not years, of emotional monitoring. Alberto Iturra, the rescue team's chief psychologist, has warned that the miners, who are like nocturnal creatures now being brought back into a life of daylight, could experience posttraumatic problems similar to those of soldiers returning from war, especially "the disappointments and frustrations of no one else understanding what they've been through." Once their international fame has passed, Iturra said recently, their families may have to muster "a lot of patience."

Fortunately, that quality seems to be in large supply among them. Margarita Rojo, 72, the mother of miner Dario Segovia, 48, says she never imagined the rescue would come this soon. She thought it could "take up to the rest of the year, to tell you the truth," Rojo told TIME. Then again, she was a miner herself as a younger woman — an explosives expert to boot. Her son, she says, "is a miner — they're like cats, with nine lives. He's got three or four left at least." For the next two days, that outpouring of life promises to light up the watching world as surely as it ignited the barren Chilean desert. (Time)

Tuesday, October 12, 2010

3 Phases in Soils

O: 4/X-1/GTK/10

Volume-weight properties

The volume-weight properties of a soil define its state. Measures of the amount of void space, amount of water and the weight of a unit volume of soil are required in engineering analysis and design. 
Soil comprises three constituent phases:
  1. Solid: rock fragments, mineral grains or flakes, organic matter.
  2. Liquid: water, with some dissolved compounds (e.g. salts).
  3. Gas: air or water vapour. 
In natural soils the three phases are intermixed. To aid analysis it is convenient to consider a soil model in which the three phases are seen as separate, but still in their correct proportions. 



Volumes of solid, water and air: the soil model
The soil model is given dimensional values for the solid, water and air components: Total volume,
V = Vs + Vw + Va
Since the amounts of both water and air are variable, the volume of solids present is taken as the reference quantity. Thus, the following relational volumetric quantities may be defined:
 

Note also that:
  • n = e / (1 + e)
  • e = n / (1 - n)
  • v = 1 / (1 - n) 

Degree of Saturation
The volume of water in soil can only vary between zero  (i.e.  a dry soil) and the volume of void, this can be expressed as  a  ratio:



For a perfectly dry soil:
Sr = 0
For a saturated soil:
Sr = 1 


Note: In clay soils as the amount water increases the volume and therefore the volume of voids will also increase, and so the degree of saturation may remain at Sr = 1 while the actual volume of water is increasing. 

Air - Void Content




The air-voids volume, Va , is that part of the void space not occupied by water. 
Air-voids content, Av
Gama v = (air-voids volume) / (total volume)
= Va / V
= e.(1 - Sr) / (1+e)
= n.(1 - Sr)
For a perfectly dry soil:
Av = n
For a saturated soil:
Av =



Masses of solid and water: water content
The mass of air many ignored. The mass of solid  particles is usually particle density or grain spesific gravity.

Grain Spesific Gravity


Particle Density

The ratio of mass of water present to mass of solid particle is called the water content or sometime the moisture content




Densities and Unit weights
Density is a measure of the quantity of mass in a unit volume of material.
Unit weight is a measure of the weight of a unit volume of material.
There are two basic measures of density or unit weight applied to soils: Dry density is a measure of the amount of solid particles per unit volume. Bulk density is a measure of the amount of solid + water per unit volume.

The preferred units of density are:
Mg/m³, kg/m³ or g/ml.
The corresponding unit weights are:


Monday, October 11, 2010

Geotechnic on Applications

O: 3/X-1/GTK/10
  1. Shallow Foundation
  2. Deep Foundation
  3. Retaining Wall
  4. Earth Dams
  5. Concrete Dams
  6. Earth Works
  7. Geofabrics
  8. Soil Nailing
  9. Sheet Piles
  10. Conferdams
  11. Landslides
  12. Shoring
  13. Tunneling
  14. Blasting
  15. Ground Improvement
  16. Environmental Geomechanics
  17. Instrumentation
  18. Soil Testing

















GROUND IMPROVEMENT



Areas of Geotechnics

O: 2/X-1/GTK/10

Traditional  Areas of Geotechnical Engineering
  1. Site Investigation
  2. Compaction
  3. Consolidation
  4. Slope Stability
  5. Retaining Walls
  6. Foundation
Site Investigation
  1. To Properly Characterize a Site requires:
    - Literature Investigation to Determine
    - What Has Happened at the Site Before (Prior History)
    - What Investigations have been Made Near the Site
    - Geology, USDA Soil Profiles, Utility Crossings, etc.
  2. On Site Surveying, Borings and Drilling, Bag Samples, etc.
  3. Laboratory Testing for Soil Properties and Classification
  4. Produce a Report about the site for the Owner
  5. Maybe develop a Foundation Design, Retaining Structures, Embankments, Cuts and Fills
Drilling Program
  1. The purpose of the Drilling Program is to determine the:
    - Thickness,
    - Lateral Extent, and
    - Physical Properties of Each Layer of Soil
    - Presence, Depth and Pressure of Water in the Soil
  2. Coupled with the Topographic Survey, This provides a 3D view of the site and the soil underneath.
    If the Upper Soils are Weak, a Deep Foundation system must be developed.
  3. This investigation may also determine where to find suitable fill material from Borrow pits.
Compaction
Ralph Proctor defined a standard procedure to specify the required density and water content of the soil for Stable Embankments.
  1. Duplicated compactive effort available by compactors in 1927-1931.
  2. Test is consistent and reliable
  3. It shows the relationship between water   content  (w) and dry unit weight  (Gama d )
Samples of soil wetted to different water contents
  • Each sample is compacted into the mold in 3 layers with 25 hammer blows per layer.
  • Water content and Dry Unit Wt. determined for each sample.
  • Peak is called Maximum Dry Unit Wt (Gamma-d Max) and Optimum Water Content
Contracts usually specify that the soil should be compacted to
A percentage of the Maximum Dry Unit Wt
     - Typically 95% for most fills
     - Sometimes 92% for landscaping
     - Sometimes 97-100% for fills requiring extra strength
B range of Water Contents around Optimum
     - Commonly 3 or 4% below and 2% above wopt.
    Cut and Fill

    If soil has to be moved around, you need to remove it (cut) at one location and, place it (Fill) at another location.

    Economically, you want to design so that
    • Minimize Volume
    • Minimize Haul
    Cut
    • Cut soil is moved most easily by pushing it around (Short Haul)
      - Scraper
      - Wheeled (or Track) Bulldozer
      - Blade
    • Lifting into a Dump Truck is much slower and expensive (usually Longer Haul)

     Cut and Fill, How Much ?
    • Survey
    • Pick Centerline
    • Draw Topo
    • Determine Sections

    • Overlay Final Surface
    • Draw Topo as Overlay
    • Determine Section

    Understanding Geotechnics

    Geotechnics
    1. Geotechnical engineering is that branch of civil engineering that deals with the influence and interaction of geological formations, materials and water, with structures.
    2. Geotechnical Engineering is the branch of civil engineering that deals with soil, rock, and underground water, and their relation to the design construction and operation of engineering projects (Coduto 1998)
    3. Soil mechanics is a discipline that applies the principles of engineering mechanics to soils to predict the mechanical behavior of soil. 
    Soil
    1. Soil is one of people’s oldest construction material
    2. Soil is one of the most complex of the standard construction materials because of the variation in soil types
    3. Soil has been studied and analyzed for hundreds of years 
    4. In Soil, Generally assume Liquid = Water   and   Gas = Air
      Properties of Soil depend on the Solid Phase and the amount and distribution of Water and Air
      Simple ratios define the state of the soil, called the Index Properties
    5. Soil is the substance existing on the earth's surface, which grows and develops plant life (Pedologist)
    6. Soil is the material in the relative thin surface zone within which roots occur, and all the rest of the crust is grouped under the term rock irrespective of its hardness. Also: unconsolidated rock, overburden (Geologist).
    7. Soil is the un-aggregated or un-cemented deposits of mineral and/or organic particles or fragments covering large portion of the earth's crust (Engineer)
    8. Soil is comprised of Solids, Liquid and Gas

    Saturday, October 9, 2010

    Sand Cone Test

    O: 5/XI-3/GTK/10

    Objective

    Determine the density of the soil layer by measuring the volume of holes directly.
     

    Equipment
    1. Sand cone
    2. Bottle sand cone
    3. Field Plate
    4. Standard Sand
    5. Chisel
    6. Rubber hammer
    7. Brick Trowel
    8. Tin
    Procedure
    1. Fill the bottle with standard sand.
    2. Weigh the bottle and cone, following graded sand that has been filled sufficiently.
    3. Clean the surface soil to be excavated and averaged.
    4. Place the plate in the soil surface in a solid position.
    5. Dig a round hole in accordance with the diameter of the hole plate with a chisel, a hammer and a brick trowel.
    6. Weigh the cans that have been cleared to be empty (W-9).
    7. Enter all the soil excavation results in the field can then weigh the weight (W-8).
    8. Place the sand cone which already contains the sand over the field plate earlier.
    9. Close the tap cone, after the sand stops flowing,
    10. Take some soil around the test is to check their water content.
    11. Weigh the sand cone containing the remaining sand in it.
    12. Calculate the weight of sand that came out of the bottle.
    13. Take back the clean sand that fills the hole had to be used in subsequent experiments.
    Calibration Equipment
    1. Weigh a cone and an empty bottle (W-1).
    2. Enter the sand into the bottle through a cone and then weighed (W-4).
    3. Place the ground plate on a clean glass surface and attach the cone following last bottle on it.
    4. Open the tap so that the sand will fill the cone below the funnel.
    5. Close the tap cone, after the sand stops flowing.
    6. Weigh the sand cone containing the remaining sand in it (W-5).
    7. Calculate the weight of sand that fills the cone bottom.
    8. Repeat this procedure 3 times and the results are averaged.
    9. The difference between the results of each experiment should not be more than 1%.
    10. Enter the sand into the bottle through a cone until full (let the sand fall freely), then weigh the following funnel (W-3), repeat 3 times in a row. take the average price, the difference between the weight of each with the average value should be no more than 1%.
    11. Measure volume by filling bottles with water until full.
    12. Weigh heavy cone and a bottle filled with water (W-2).  
    13. Repeat the procedure 10 s / d 12 2 twice.
    Maintenance
    1. Lubricate valve mouthpiece regularly with oil to prevent rust / jam.
    2. Drying sand gradation when it is damp / sticky
    Picture
     Application in the Field

     Balance (20 kg)
    Balance 311

     Oven

     


    Result