Seismic Measurements and Geotechnical Engineering Lecture

Details

Title	Seismic Measurements and Geotechnical Engineering Lecture
Duration	90 Mins
Language	English
Format	MP4
Size	249 MB

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Design of Sheet Pile Walls Manual

This manual provides information on foundation exploration and testing procedures, analysis techniques, allowable criteria, design procedures, and construction consideration for the selection, design, and installation of sheet pile walls.

The guidance is based on the present state of the technology for sheet pile-soil-structure interaction behavior. This manual provides design guidance intended specifically for the geotechnical and structural engineer.

It also provides essential information for others interested in sheet pile walls such as the construction engineer in understanding construction techniques related to sheet pile wall behavior during installation.

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What is LANDLOCK And How It Works?

LANDLOCK Advantages For Roads

Road designs vary greatly from country to country, but are generally calculated based on the performance metrics that need to be achieved. A super-highway will have a much larger profile of design than a rural road. However, all road profiles generally have three basic layers: a drainage layer, base and wear-course.

Just like a chain, every road is only as strong as its weakest link. Herein lies the problem. When a wear-course like asphalt begins to fail, evident by cracking and potholes, generally it is due to failures at the base or sub-base. Why then during construction would these critical layers only be compacted with water and therefore left “unstabilized,” and susceptible to water and vibratory erosion?

When integrating LANDLOCK into one (or all) of these three layers/sections of the road, it allows builders to gain several critical advantages that significantly reduce the traditional waste associated with modern road construction.

Advantages for Primary/Urban Roads & Highways

Profile Reduction

Based on extensive lab and field testing, a LANDLOCK^® treated base will be 2-20 times stronger than an unstabilized base. This means that engineers can significantly reduce the profile of design of the road and still achieve the required performance metrics. A smaller profile of design means less material. At the same time, builders will see a reduction in material spreading and transportation costs, while simultaneously increasing production rates. The entire construction process is more efficient and less wasteful – Smarter Infrastructure.

Extended Life Cycle

As mentioned above, traditional wear-courses like asphalt are only as good as their base. It is only logical then that a wear-course laid on a rock-hard, erosion free LANDLOCK^® treated base will last much longer than when laid on an unstabilized base. A longer life means less money being wasted on costly maintenance work, leaving more money to spend in other areas.

Advantages for Feeder/Farm-to-Market Roads

Paving/Stabilizing Dirt and Gravel Roads

Across the world, even in developed countries, there are millions of miles of unpaved roads that are a constant source of fugitive dust and waste given their need for constant maintenance. Because unpaved roads have no protection from rainfall, water erosion will turn a newly graded, rural road into a muddy mess, that once dried out, is then covered with potholes and washboarding. It is a vicious cycle that, previously, was impossible to win.

Source: http://www.landlocknaturalpaving.com

What type of pavement is used for airports runway?

The materials used for airports is generally the same as what is used for roadways, however, the depths, or thicknesses are different, and the tolerances are much tighter at an airport. The material for runways usually needs to meet a much tighter spec.

A typical section for an airport can use asphalt or concrete. Below is a generic look at the structural section for either asphalt or concrete from an FAA Advisory Circular on Aiport Pavement Design and Evaluation.

You will notice that the materials in the middle are thicker and then taper to thinner. This is because the loads on the runway are primarily from the 2 landing wheels, which will be in the middle of the runway. The effective tire width is pictured below.

The surface must be smooth and well bonded, and resistant to the shear stresses of the airplane wheel loads. The non-skid surface must not cause undue wear on the airplane tires . The surface must be free of loose particles that could damage the airplane or people. In order to meet this requirement, there must be good control of the mix. This usually requires a central mixing plant be used for the hot mix asphalt.

The base course is integral to flexible pavement design such as asphalt. The loading in flexible pavements transfers downward and outward. For this reason, the base, subbase, if used, and subgrade contribute to the strength of the pavement section. For concrete pavement, the concrete provides the strength to the structural section.

The base course must be of sufficient quality that it won’t fail, or allow failure in the subgrade. It must be able to withstand the forces from the airplane wheel loading without consolidating which would cause the surface course to deform. The base course uses very select material with very hard and durable aggregate. The requirements for the base course are very strict.

Soil Boring Log Excel Template

Description:

The boring log is the basic record of almost every geotechnical exploration and provides a detailed record of the work performed and the findings of the investigation. The field log should be written or printed legibly and should be kept as clean as is practical. All appropriate portions of the logs should be completed in the field prior to completion of the field exploration.
A wide variety of drilling forms are used by various agencies. The specific forms to be used for a given type of boring will depend on local practice. Typical boring log, core boring log and test pit log forms endorsed by the ASCE Soil Mechanics & Foundations Engineering Committee.

-Topographic survey data including boring location and surface elevation, and benchmark location and datum, if available.
-An accurate record of any deviation in the planned boring locations.
-Identification of the subsoils and bedrock including density, consistency, color, moisture, structure, geologic origin.
-The depths of the various generalized soil and rock strata encountered.
-Sampler type, depth, penetration, and recovery.
-Sampling resistance in terms of hydraulic pressure or blows per depth of sampler penetration. Size and type of hammer. The height of the drop.
-Soil sampling interval and recovery.
-Rock core run numbers, depths & lengths, core recovery, and Rock Quality Designation (RQD)
-Type of drilling operation used to advance and stabilize the hole.
-Comparative resistance to drilling.
-Loss of drilling fluid.
-Water level observations with remarks on possible variations due to tides and river levels.

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Permeability of Soil: Definition, Darcy’s Law and Tests

Definition of Permeability:

It is defined as the property of a porous material which permits the passage or seepage of water (or other fluids) through its interconnecting voids.

A material having continuous voids is called permeable. Gravels are highly permeable while stiff clay is the least permeable, and hence such a clay may be termed impermeable for all practical purpose.

The study of seepage of water through soil is important for the following engineering problems:

1. Determination of rate of settlement of a saturated compressible soil layer.

2. Calculation of seepage through the body of earth dams and stability of slopes for highways.

3. Calculation of uplift pressure under hydraulic structure and their safety against piping.

4. Groundwater flow towards well and drainage of soil.

Darcy’s Law (1856) of Permeability:

For laminar flow conditions in a saturated soil, the rate of the discharge per unit time is proportional to the hydraulic gradient.

q = kiA

v = q/A = Ki … (7.1)

Where q = discharge per unit time

A = total cross-sectional area of soil mass, perpendicular to the direction of flow

i = hydraulic gradient

k = Darcy’s coefficient of permeability

v = velocity of flow or average discharge velocity

If a soil sample of length L and cross-sectional area A, is subjected to differential head of water h₁– h₂, the hydraulic gradient i will be equal to [(h₁– h₂)/L] and we have q = k. [(h₁– h₂)/L].A.

When hydraulic gradient is unity, k is equal to V. Thus, the coefficient of permeability, or simply permeability is defined as the average velocity of flow that will occur through the total cross-sectional area of soil under unit hydraulic gradient. Dimensions are same as of velocity, cm/sec.

The coefficient of permeability depends on the particle size and various other factors. Some typical values of coefficient of permeability of different soils are given in Table 7.1.

Discharge Velocity and Seepage Velocity:

The total cross-sectional area of the soil mass is composed of sectional area of solids and voids, and since flow cannot occur through the sectional areas of solids, the velocity of flow is merely an imaginary or superficial velocity.

The true and actual velocity with which water percolates through a soil is called the velocity of percolation or seepage velocity. It is the rate of discharge of percolating water per unit of net sectional area of voids perpendicular to the direction of flow.

Validity of Darcy’s Law:

In accordance with the Darcy’s Law, the velocity of flow through soil mass is directly proportion to the hydraulic gradient for laminar flow condition only. It is expected that the flow to be always laminar in case of fine-grained soil deposits because of low permeability and hence low velocity of flow.

However, in case of sands and gravels flow will be laminar upto a certain value of velocity for each deposit and investigations have been carried out to find a limit for application of Darcy’s law.

According to researchers, flow through sands will be laminar and Darcy’s law is valid so long as Reynolds number expressed in the form is less than or equal to unity as shown below –

Where v = velocity of flow in cm/sec

D_a = size of particles (average) in cm.

It is found that the limiting value of Reynolds number taken as 1 is very approximate as its actual value can have wide variation depending partly on the characteristic size of particles used in the equation.

Factors affecting permeability are:

1. Grain size

2. Properties of pore fluid

3. Void ratio of the soil

4. Structural arrangement of the soil particle

5. Entrapped air and foreign matter

6. Adsorbed water in clayey soil

4. Effect of degree of saturation and other foreign matter

k will decrease if air is entrapped in the voids thus reducing its degree of saturation. Percolating water in the field may have some gas content, it may appear more realistic to use the actual field water for testing in the laboratory.

Organic foreign matter also has tendency to move towards critical flow channels and choke them up, thus decreasing permeability.

5. Effect of adsorbed water – The adsorbed water surrounding the fine soil particle is not free to move, and reduces the effective pore space available for the passage of water.

Capillarity-Permeability Test:

The set-up for the test essentially consists of a transparent tube about 40 mm in diameter and 0.35 m to 0.5 m long in which dry soil sample is placed at desired density and water is allowed to flow from one end under a constant head, and the other end is exposed to atmosphere through air vent.

At any time interval t, after the commencement of the test, Let the capillary water travel through a distance x, from point P to Q. At point P, there is a pressure deficiency (i.e., a negative head) equal to h_c of water.

If the coefficient of permeability is designated as k_u at a partial saturation S, the above expression can be rewritten as –

In order to find the two unknowns k and h_c in the above equation, the first set of observations are taken under a head h₁. As the capillary saturation progresses the values of x are recorded at different time intervals t.

The values of x² are plotted against corresponding time intervals t to obtain a straight line whose slope, say m, gives the value of [(x²₂– x²₁)/(t₂ – t₁)] . The second set of observation are taken under an increased head h₂ and values of x² plotted against corresponding values of t to obtain another straight line, whose slope m₂ will give the value [(x²₂– x²₁)/(t₂ – t₁)].

By substitution in Eqn. 7.1, we obtain the following two equations, which are solved simultaneously to get k and h_c.

The porosity n required in the above equation is computed from the known dry weight of soil, its volume and specific gravity of soil particles.

Permeability of Stratified Soil Deposits:

In general, natural soil deposits are stratified. Each layer may be homogeneous and isotropic. When we consider flow through the entire deposit the average permeability of deposit will vary with the direction of flow relative to the bedding plane. The average permeability for flow in horizontal and vertical directions can be readily computed.

Average Permeability Parallel to Bedding Plane:

Figure 7.9 shows several layers of soil with horizontal stratification. Let Z₁, Z₂, ….Z_n be the thickness of layers with permeabilities k₁, k₂, … k_n.

For flow parallel to bedding plane the hydraulic gradient i will be same for all layers. The total discharge through the deposit will be the sum of discharges through individual layers.

Average Permeability Perpendicular to Bedding Plane:

For flow in the vertical direction for the soil layers shown in Fig. 7.10.

In this case the velocity of flow, v will be same for all layers the total head loss will be sum of head losses in individual layers.

h = h₁ + h₂ + h₃ + … + h_n (i)

If k_z denotes average permeability perpendicular to bedding plane, applying Darcy’s law, we have –

How to Test Compaction of Soil?

Compaction test is conducted in the laboratory to determine the relation between the dry density and the water content of the given soil compacted with standard compaction energy and to determine the OMC corresponding to the MDD.

The OMC obtained from the laboratory compaction test will help in deciding the amount of water to be used for compaction in the field. The MDD obtained from the laboratory compaction test helps in knowing the dry density achievable in the field compaction and also as a check for quality control.

Based on the compacted energy used in compacting the soil in the laboratory test, the laboratory compaction tests are of two types:

1. Standard Proctor test.

2. Modified Proctor test.

1. Standard Proctor Test:

In this test, the soil is compacted in three layers, each layer subjected to blows of a rammer with falling weight of 5.5 pounds (2.6 kgf) falling through a height of 12 in. in a cylindrical mold of internal diameter of 4 in. and effective height of 4.6 in.

The compaction parameters in a standard Proctor test are – W is the weight of rammer blow = 5.5 pounds, h is the height of fall = 12 in. = 1 ft, n is the number of blows per layer = 25, l is the number of layers = 3, and V_m is the volume of the mold = 1/30 cubic ft. The total compaction energy imparted on the soil per unit volume in this test is –

IS – 2720 (Part 7) – 1980 recommends the Indian Standard light compaction method based on standard Proctor test in metric system. The standard Proctor test or IS light compaction can be used as a criteria for the compaction of subgrades on highways and earth dams, where light rollers are used.

2. Modified Proctor Test:

Advances in construction technology resulted in the development of heavier rollers, which impart higher compaction energy during field compaction. To provide a laboratory control criterion for the higher compaction energy, the modified Proctor test was developed and standardized by the American Association of State Highway (and Transportation) Officials (AASHO or AASHTO) and by US Army Corps of Engineers for airfield construction.

In modified Proctor test, the soil is compacted in the same mold as in standard Proctor test, which has internal diameter of 4 in. and affective height of 4.6 in. giving a total internal volume of 57.805 cubic in. or 1/30 cubic ft. The rammer is bigger with a hammer of weight 10 pounds (4.5 kgf) falling through a height of 18 in. The soil is compacted in five layers, each layer being given 25 blows.

The compaction parameters in modified Proctor test are as follows – W is the weight of hammer blow = 10 pounds, h is the height of fall = 18 in. = 1.5 ft, n is the number of blows per layer = 25,l is the number of layers = 5, and V_m is the volume of the mold = 1/30 cubic ft.

The compaction energy imparted to the soil, per unit volume, in the modified Proctor test is:

Thus, the compaction energy in the modified Proctor test is (56250/12375) 4.55 times that in standard Proctor test.

If the soil fraction retained on 20 mm sieve is more than 5%, a bigger mold of 5.9 in. (15 cm) internal diameter and 5 in. (12.73 cm) internal height giving a total volume of 137.04 cubic in. or 1/12.611 cubic ft (2250 cm³) is used. When the bigger mold is used, the soil is compacted with 56 blows for each layer.

IS – 2720 (Part VII) – 1980 and Part VIII-1983 have recommended procedures corresponding to these two tests as follows:

1. IS light compaction test.

2. IS heavy compaction test.

1. IS Light Compaction Test:

The objective of the IS light compaction test is to determine the relation between the water content and the dry density of compacted soil and to determine the MDD and OMC from this test. The compaction energy used to compact the soil corresponds to that of standard Proctor test.

The compaction parameters in IS light compaction test are as follows – W is the weight of hammer blow = 2.6 kgf, h is the height of fall = 31 cm, n is the number of blows per layer = 25, and I is the number of layers = 3, and V_mis the volume of the mold = 1000 cubic centimeter (cc). The total compaction energy imparted on the soil in this test is –

E = Whnl = 2.6 × 31 × 25 × 3 = 6045 kgf cm

The total compaction energy imparted on the soil per unit volume in this test is –

E = 6045/1000 = 6.045 kgf cm/cm³

2. IS Heavy Compaction Test:

The IS heavy compaction test is similar to IS light compaction text except for the following differences:

1. A heavy rammer of 4.9 kgf falling weight that falls through a height of 45 cm is used for compacting the soil in IS heavy compaction.

2. The soil is compacted in five layers of equal thickness in the compaction mold.

3. The initial water content to be used in the first trial is 3%-5% for sandy and gravelly soils and 12%-16% below plastic limit for cohesive soils.

To increase the accuracy of the test results, it is desirable to reduce the increment of water in the region of OMC.

Shifting and Tilting of Well Foundations

Shifting and tilting problems occurs generally during sinking process of well foundations. If proper care is not taken, they will cause serious problems and weaken the stability of foundations. Precautions to avoid shifting and tilting, limitations and rectifying methods are discussed below.

Shifting and Tilting of Well Foundations

When the well is moved away horizontally from the desired position, then it is called shifting of well foundation.
When the well is sloped against vertical alignment,it is called tilting of well foundation.

Precautions to Prevent Shifting and Tilting

It is safer and economical to avoid tilting and shifting of wells by adopting the following preventive measures:

The outer surface of the well curb and steining should be level, straight, and smooth.
The radius of the well curb should be kept 2-4 cm more than the outer radius of the well steining.
The cutting edge should be sharp and of uniform thickness.
The steining should be built in lifts and the entire steining height should be built in one straight line from bottom to top at right angles to the plane of the curb.
Dredging should be uniform on all sides of the well. For a twin well, dredging should be uniform in both the wells.
The well should be constructed in stages of small height increments.
The magnitude and direction of sinking of wells should be properly and carefully monitored on a continuous basis to identify any tilt or shift and adopt appropriate corrective measures immediately to rectify the same.
If the well shows a tendency for tilting, dredging should be done on the higher side. If this does not bring required improvement, sinking should be stopped and should be resumed only after the tilting is corrected.
Dredged material should not be deposited unevenly around the well.
When a kentledge is used to provide additional sinking effort, it should be placed evenly on the loading platform.

Limitations

The maximum tilt allowed in case of well foundation is 1 in 60.
The shift in well foundation should not be more than 1 % of depth of sunk.
Beyond the above limits, well foundation is considered as dangerous and in such a case, remedial measures to rectify shifting and tilting should be followed.

Rectifying Methods

Rectifying methods for Rectification of shifting and tilting problems in well foundations are as follows:

Eccentric loading
Excavation on higher side
Water jetting
Pulling the well
Using hydraulic jacks
Using struts
Excavation under cutting edge
Wood sleeper under cutting edge

1. Eccentric loading

The well tilt can be rectified by placing eccentric loading on the higher side. Higher side is nothing but the opposite side of tilt or lower side.
A loading platform is constructed on the higher side and load is placed on it.
This eccentric load will increase downward pressure on higher side and correct the tilt.
The amount of load and eccentricity is decided based on the depth of sinking.
Greater is the depth of sinking of well, larger will be the eccentricity and load.

2. Excavation on Higher Side

When well is tilted to one side, excavation should be increased on the other side which is opposite to tilted side.
This technique is useful only in the initial stages of well sinking.

3. Water Jetting

Water jetting on external surface of well on the higher side is another remedial measure for rectifying tilt.
When water jet is forced towards surface of well, the friction between soil and well surface gets reduced and the higher side of well becomes lowered to make well vertical.

4. Pulling the Well

The well can be pulled towards higher side using steel ropes.
One or more steel ropes are wound around the well with wooden sleepers packed in between well and ropes to prevent damage to the well steining by distributing load over to larger area of steining.
Pull should be carefully done otherwise,shifting of well foundation may occur.

5. Pushing using Jacks

Another method to rectify tilting and shifting of well foundation is using hydraulic jacks or mechanical jacks, the tilted well can be pushed from lower side to higher side.
Neighbor vertical well foundations or suitable arrangements made will give support to the jack system.
Care should be taken while pushing the well otherwise the well may shifts.

6. Using Struts

By providing struts as supports on the lower side or tilted side of well, further tilting can be prevented.
Wooden sleepers are provided between struts and well steining to prevent damage to well steining and to distribute pressure to larger area.
Struts are rested on firm base having driven piles.

Fig 6: Strutting the Well From Lower Side

7. Excavation under Cutting Edge

This technique is used for hard strata soils. In this method, the well is de-watered first and open excavation is carried out exactly under the cutting edge on the higher side.
If de-watering is not possible, soil strata is loosened using suitable equipment with the help of professional divers.

8. Wood Sleeper under Cutting Edge

If tilting towards lower side is increasing,then wooden sleepers are placed under cutting edge on lower side to control the tilting temporarily.
When well is corrected to vertical level, this sleepers can be removed.

Deadliest Landslides In Recorded History

Some single landslide events have killed numbers in excess of the populations of small countries.

Landslides are life-threatening events that can make it seem as though the world we live upon is crumbling around us. Those landslides listed below are some of the deadliest in recorded human history, each taking away human life by the thousands.

10. Diexi Slides, Sichuan, China, August 1933 (3,000+ deaths)

On August 5, 1933, a strong earthquake triggered a massive landslide in Diexi, Mao County, Szechwan, China. The event, known as the Diexi Slides, claimed more than 3,000 lives, and destroyed many villages within the affected region. The old town of Diexi suffered the worst fate of all as it sank into the landslide-created dam below.

9. Khait Landslide, Tajikstan, July 1949 (4,000 deaths))

For centuries, the mountainous belt running through Central Asia has witnessed a large number of disasters involving earthquake-triggered landslides. One such natural catastrophe occurred in July of 1949, when the 7.4 magnitude Khait Earthquake triggered hundreds of landslides near the southern limits of the Tien Shan ranges in central Tajikistan. The adjacent valleys of Yasman and Khait were the most affected by these earthquake-induced landslides. The Khait Landslide involved rockslides with saturated loess travelling at an estimated average velocity of around 30 meters per second. Approximately 4,000 people were killed in this tragic natural disaster.

8. 62 Nevado Huascaran Debris Fall, Ranrahirca, Peru, January 1962 (4,500 deaths)

Mount Huascarán is a famous Peruvian mountain with a snowcapped peak that rises to a height of 22,205 feet. In January of 1962, a thaw triggered the breaking off of a portion of the north summit of the mountain, leading to a landslide/avalanche that led to the tragic death of nearly 4,500 people. The avalanche, locally referred to as ‘Huayco’, involved a massive ice sheet that was estimated to be about 1 kilometer wide and 40 feet high. As the ice sheet moved rapidly down the slopes, it gathered rock and debris from the mountain and strengthened in force, completely burying several villages in Ranrahica underneath it.

7. Huaraz Debris Flows, Ancash, Peru, December 1941 (5,000 deaths)

In December of 1941, the residents of Huaraz, a Peruvian city in the Ancash region, were completely unaware that a retreating glacier tongue above their city would soon be responsible for wreaking havoc its people and claim thousands of the lives living within. Just before dawn on December 13, 1941, disaster struck the Peruvian city when a landslide resulted in glacial ice crashing down into Lake Palcacocha, generating huge waves that completely destroyed the dam on the lake. This released large volumes of water, itself laden with mud, rock, and ice, into the valley below with an unimaginably high force. Another dam in the nearby Lake Jircacocha was also broken by the flowing glacial water, resulting in the furious waters of both of the two lakes emptying themselves onto the city of Huaraz, claiming more than 5,000 lives in the process.

6. Kelud Lahars, East Java, Indonesia, May 1919 (5,000+ deaths)

Mount Kelud, in Eastern Java, Indonesia, is quite infamous as an extremely active, hazardous volcano, and one which has erupted about 30 times in the past killing thousands of people in its volcanic disasters. One of the deadliest eruptions of this volcano occurred on May 19, 1919, when over 38 million cubic meters of water were expelled from the crater lake of the volcano, which had accumulated large amounts of sediment and volcanic material to form lethal lahars. The lahars moved down the mountains with high velocity and swept away and drowned all that were unfortunate enough to be in its path.

5. North India Flood mudslides, Kedarnath, India, June 2013 (5,700 deaths)

One of the worst natural disasters in the history of India occurred in June of 2013, when powerful flash floods killed around 5,700 people in the Himalayan state of Uttarakhand. Consistent cloudbursts and incessant monsoon rainfall were primarily held responsible for the disaster, which has been officially termed as a natural calamity. However, a section of environmentalists, scientists, and the educated public think otherwise. According to them, thoughtless human intervention in the Himalayan mountain ecosystem had rendered the ecosystem extremely fragile and prone to disaster. The unchecked tourism in the region had promoted the rapid growth of hotels, roads, and shops throughout the region without paying heed to the environmental laws and demands of the ecosystem. The mushrooming of hydroelectric dams in Uttarakhand was also another important factor held responsible for the environmental damage. Heavy rainfall had been previously recorded in the region which had also led to flash floods, but the devastation produced in 2013 was comparable to no earlier data. It is believed that floodwaters had no outlets this time, as most of the routes taken by the water previously were now blocked by sand and rocks. Hence, the lethal waters, laden with debris from dam construction and large volumes of mud and rocks, inundated towns and villages and buried all forms of life that came in its way.

4. 70 Nevado Huascaran Debris Fall, Yungay, Peru, May 1970 (22,000 deaths)

In May of 1970, an earthquake triggered a massive series of landslides and avalanches of rock and snow that buried the towns of Yungay and Ranrahirca. Nearly 22,000 people perished in this natural disaster. The avalanche travelled a distance of 16.5 kilometers. It ended up carrying 50-100 million cubic meters of water, mud, and rocks, which reached the village of Yungay and smothered all life forms therein under its deadly cover.

3. Armero Tragedy, Tolima, Colombia, November 1985 (23,000 deaths)

A dormant volcano, the Nevado del Ruiz in Tolima, Colombia, suddenly came to life on November 13, 1985, wreaking havoc on the nearby villages and towns, and killing as many as 23,000 people. A pyroclastic flow from the crater of the volcano had melted the glaciers in the mountain and sent deadly lahars, saturated with mud, ice, snow, and volcanic debris, rushing down the mountain at killer speeds towards the residential areas directly below it. The lahars soon engulfed the town of Armero, killing thousands there, while casualties were also reported in such other towns as Chinchiná

2. Vargas Tragedy, Vargas, Venezuela, December 1999 (30,000 deaths)

The Winter of 1999 witnessed unusually heavy rainfall in the Vargas State of Venezuela. The rainfall triggered a series of large and small flash floods and debris flows that claimed around 30,000 lives in the region. As per estimates, approximately 10% of the population of Vargas perished in the disaster. The entire towns of Carmen de Uria and Cerro Grande completely vanished under the mud bed, and a large number of homes were simply swept away into the nearby ocean.

1. Haiyuan Flows, Ningxia, China, December 1920 (100,000+ deaths)

The 8.5-magnitude Haiyuan Earthquake was the world’s second deadliest earthquake of the 20th Century. It generated a series of 675 major loess landslides causing massive destruction to lives and property. The natural calamity which struck the rural district of Haiyuan on the evening of December 16, 1920 claimed over 100,000 lives, and severely damaged an area of approximately 20,000 square kilometers. The worst affected areas included the the epicenter of the earthquake in the Haiyuan County in what is now the Ningxia Hui Autonomous Region, as well as the neighboring provinces of Gansu and Shaanxi. Haiyuan County alone lost more than 50% of its population in the disaster. One of the landslides buried an entire village in Xiji County as well.

Source: https://www.worldatlas.com

Contiguous Piled Wall With Ground Anchor Support Design Spreadsheet

Contiguous Piles, structures made of piles, and pile-like structures are useful structural elements to support deep excavations and cuts in slopes, and to retain creeping or sliding slopes, not uncommonly in seismic areas.

Depending on the static system and the dimensions the structural elements transfer forcesmainly by shear (“dowel”) and/or mainly by bending (“beam”) to the ground.

In numerous cases they are particularly effective in combination with otherstructural measures like (pre-stressed)

anchors and/or drainage systems. The paper presents case histories including piles and pile-like structures, which are applied for retaining structures in slopes.

The main focus is on infrastructureprojects in creeping slopes. Two case historiesfrom Austria and Sloveniaare presented in detail. Miscellaneous projects from European countries concentrating on various aspects complement

the contribution.