how to repair slope failure

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How to mitigate slope failure and repair?

Below are some of the common methods used for slope failure mitigation and repair: Contractors who know what they’re doing will always draw up drainage plans to complement their slope repair plans. As discussed here and here, excessive water in slopes is never good. To name a few compelling reasons:

What are the different types of slope failure?

Types of Slope Failure. Slope failures depend on the soil type, soil stratification, groundwater, seepage, and the slope geometry. We will introduce a few types of slope failure that are common in soils. 1. Translational Slide. Failure of a slope along a weak zone of soil is called a translational slide (Figure 16.2a).

What is slope failure in soil?

Slope failures depend on the soil type, soil stratification, groundwater, seepage, and the slope geometry. We will introduce a few types of slope failure that are common in soils.

How to prevent slope stabilization on slopes?

Similarly, digging out soft soils and replacing them with gravel that is less compressive is one way to prevent failure above slopes which trickles down to the slope stabilization below. Other solutions structural engineering provides solutions like retaining walls, thorough soil compaction, and drainage methods to prevent saturation and seepage.

How do you solve slope failure?

Slope failure can be prevented by providing a berm (horizontal surface between exterior slope) below the toe of the slope which increases the resistance force to movement of the soil and this is the best way to avoid base failure.

How do you stabilize slopes?

Slopes can be stabilized by adding a surface cover to the slope, excavating and changing (or regrading) the slope geometry, adding support structures to reinforce the slope or using drainage to control the groundwater in slope material.

How do you fix a landslide?

There are also various direct methods of preventing landslides; these include modifying slope geometry, using chemical agents to reinforce slope material, installing structures such as piles and retaining walls, grouting rock joints and fissures, diverting debris pathways, and rerouting surface and underwater drainage.

What are 5 causes of slope failure?

Causes of Slope Failure.Erosion.Rainfall.Earthquakes.Geological Features.External Loading.Construction Activities.Rapid Drawdown.

What is the most common method of slope stabilization?

Common Types of Slope Stabilization MethodsDrainage Systems. Water drainage and precipitation can severely weaken slopes. ... Vegetation. On slopes where the angle of incline is not steep, planting vegetation is an effectual and nonintrusive method for stabilization. ... Retaining Walls.

How do you hold soil on a slope?

1:448:47Use These Plants on your Slope to Prevent Erosion, Stabilize Soil, and ...YouTubeStart of suggested clipEnd of suggested clipApplication. And there's very little maintenance. Involved with it maybe just a pruning once orMoreApplication. And there's very little maintenance. Involved with it maybe just a pruning once or twice a year it honestly it doesn't need that much you guys this is a fantastic plant in general. And

Can landslide Be Fixed?

Some of the most commonly used techniques to stop or prevent a landslide include constructing a buttress at the toe, mass excavation to unload the head, draining the slide surface to increase internal strength, and installing tieback anchors, soldier piles, and/or micro-piles to provide additional external resisting ...

What are the three types of slope failures?

Types of slope failure in geotechnical engineeringRotational failure. When rotational failure occurs, the failed surface will begin to move outwards and downwards. ... Translational failure. ... Compound failure. ... Wedge failure.

How do you prepare for a landslide?

Prepare for landslides by following proper land-use procedures – avoid building near steep slopes, close to mountain edges, near drainage ways or along natural erosion valleys. Become familiar with the land around you. Learn whether debris flows have occurred in your area by contacting local city or county officials.

What are 3 factors that make slope failure more likely?

Common Causes of Slope FailureSteepness of the Slope. It goes without saying that the steeper a slope is, the more unstable it will be. ... Water and Drainage. Water is several times heavier than air. ... Soil Composition. ... Joints & Fractures.

Which feature can strengthen slopes?

Plant roots add strength and cohesion to slope materials. They act like steel rebar reinforcements in concrete and increase the resistance of a slope to landsliding. Vegetation also adds weight to a slope. Water is almost always directly or indirectly involved with landslides, so its role is particularly important.

What are the factors controlling slope failure?

Slope stability is ultimately determined by two factors: the angle of the slope and the strength of the materials on it. In Figure 15.2 a block of rock situated on a rock slope is being pulled toward Earth's centre (vertically down) by gravity.

How do you stop erosion on a slope?

Techniques for steep slopes include wood retaining walls, interlocking concrete blocks, rock retaining walls, riprap (loose rock) areas, and terracing. If you choose wood, make sure the wood is treated with a wood preservative to prevent rotting.

How do you retain a steep slope?

Landscaping on SlopesStabilize With Plants & Trees. A smart way to stabilize the soil on a hill is by planting shrubs, trees, and flowers. ... Install Stairs or a Path. If your slope is not too steep, installing a stone path or stairs in your landscape can be a good option. ... Build Up Tiers of Walls. ... Build a Deck.

What are slope protection methods?

Slope protection approaches discussed below include erosion control blankets and turf reinforcement mats, which can also be used for ditch protection, surface roughening, slope drains, gabion structures, and cellular mats.

What is meant by slope stabilization?

Slope stabilization refers to any implemented technique that aims to stabilize an unstable or inadequately stable slope. The purpose of slope stabilization techniques is to increase the Factor of Safety of a slope to a level that is considered adequate.

What causes slope failure?

Slope failures are caused, in general, by natural forces, human misjudgment and activities, and burrowing animals.

What are the factors that determine slope failure?

Slope failures depend on the soil type, soil stratification, groundwater, seepage, and the slope geometry.

What is failure of a slope along a weak zone of soil called?

Failure of a slope along a weak zone of soil is called a translational slide (Figure 16.2a). The sliding mass can travel long distances before coming to rest.

What type of failure is a rotational slide?

A common type of failure in homogeneous fine-grained soils is a rotational slide that has its point of rotation on an imaginary axis parallel to the slope.

Why does construction near the toe of an existing slope cause failure?

Construction activities near the toe of an existing slope can cause failure because lateral resistance is removed (Figure 16.3g).

What is the third type of rotational failure?

The third type of rotational failure is the slope slide, whereby the failure surface passes through the slope (Figure 16.2d).

What would happen if the water level in a reservoir was low?

If the water level in the reservoir remains at low levels and failure did not occur under the undrained condition, seepage of groundwater would occur, and the additional seepage forces could provoke failure (Figure 16.3j).

What caused the slope failure on Idlewood Road?

Summary: As a result of severe spring rainstorms, a slope failure occurred on an embankment in Marin County (Applicant). Storm water runoff resulted in a slope failure that damaged the road surfaces on Idlewood Road and Crown Road. FEMA prepared PW 828 for $417,707 to stabilize the slope and repair the damaged roads. Based on investigations by the Applicant’s geotechnical consultants, FEMA determined that Public Assistance funding was not eligible to stabilize the failed slope due to evidence of a pre-existing slip plane observed during the technical investigations and records of a landslide event that occurred at the site in 1982.

What happened to Idlewood Road in Marin County?

Severe rainstorms from March 29, 2006, through April 16, 2006, resulted in significant storm water runoff from the uphill side of a slope in Marin County. Storm water drained across Idlewood Road and down the adjacent earthen embankment resulting in a slope failure that damaged the road surfaces of Idlewood Road and Crown Road. FEMA prepared PW 828 for $417,707, to repair the roadways and stabilize the failed slope. However, FEMA denied funding because it determined that the slope failure was not the result of the disaster but was due to a pre-existing slide plane found below the site during the geotechnical investigations. If a site is unstable, the Applicant is responsible for stabilizing the site. After the site is stabilized, the cost to restore the facility is eligible.

Can a PW be reimbursed for repairs to a non-Federal road?

However, the Applicant did not submit documentation that demonstrates that the slope has been stabilized. If the Applicant can provide such documentation to the Region, a PW will be prepared to reimburse the Applicant for repair costs for non-Federal roads.

Why did the RA deny the appeal?

On May 16, 2013, the Acting Regional Administrator (RA) issued a decision denying the Applicant’s first appeal because FEMA determined the embankment had pre-existing documented instability that must be stabilized, pursuant to RP9524.2, before PA funds could be provided for any repairs. The RA cited to FEMA’s Geotechnical Site Visit Report, listing six factors that FEMA’s Geotechnical Specialist described to show that the site was unstable prior to the disaster:

What is the second appeal denial of Morton Hill?

In its second appeal, dated September 13, 2013, the Applicant requests assistance for emergency repair measures to stabilize the Morton Hill embankment. The Applicant provides a report from Delaware Engineering, PC (Consultant), which it contracted with after the first appeal denial to review the project and Morton Hill Road and embankment history. Through the Consultant’s site assessment and review of the area’s previous repairs, it concluded that the embankment was stable prior to being destabilized by the 2011 disaster. Further, the Consultant concluded that the embankment failure was not due to previous instability or progressive failure but rather “directly linked to the intensified and concentrated runoff generated during the storm event.” The Consultant’s report addresses the six factors that the RA considered in denying the first appeal, and provides a different opinion regarding each. [5]

What is FEMA RP9524.2?

FEMA RP9524.2, Landslides and Slope Stability Related to Public Facilities, at 4-5.

Is work required as the result of a disaster eligible for FEMA?

Generally, work required as the result of a disaster is eligible. [6] According to FEMA RP 9524.2, “FEMA must determine the stability of the site where the damaged facility is located before it can approve funding to repair or restore an eligible facility and its integral ground…If a site is unstable and the instability is the direct result of the declared disaster, FEMA will fund the permanent repair or restoration of an eligible facility and its integral ground.” [7]

Is the retaining wall eligible for funding?

Conclusion: Emergency work to stabilize the embankment and the permanent work to restore the damaged facilities (the road and retaining wall) and the integral ground are eligible for funding. Hazard mitigation measures meeting eligibility requirements may also be eligible.

Is Morton Hill Road unstable?

The Morton Hill Road site was not unstable prior to the event; rather, the damage was caused by the disaster. Thus, emergency work to stabilize the embankment and the permanent work to restore the road, retaining wall, and the integral ground are eligible for funding.

Why does a slope fail?

These changes are often due to cooling or erosion that impacts rocks in upper layers. As cracks increase in the rocks, the structural integrity decreases so that, over time, the slope is more prone to fail due to these slight changes. Of course, sudden shocks to the rocks – and the soil – also have the potential to cause sudden failure like ...

What are the factors that contribute to slope failure?

In the case of natural slopes, the soil composition, degree of vegetation cover, moisture content, and water level are all factors that can accelerate slippage and sloughing in slopes.

How does internal friction affect soil?

Each soil type has its own internal friction angle. This angle effectively informs the engineer to what degree that soil can be stacked without sliding. For example, if a grain of sand has an internal friction angle of 35 degrees, then any pile of that sand you create would tumble down to a natural settlement whose sides match about 35 degrees as well. If you know the approximate internal friction angle of your soil type, then you can judge if it has been compacted in too steep of a slope for it to maintain its shape and not slip dangerously over time. Sometimes altering the soil’s composition is another technique for increasing the internal friction angle of the whole.

What to look for when constructing a slope?

If constructing a new slope, it is vital to collect the information that will show what kinds of soils and soil behaviors you’ll be working with. Once you know your stratigraphy, moisture contents, and water levels, you can predict the kind of challenges you need to plan for and ensure your inspector oversees every detail of the compaction process. If you are monitoring an existing slope, you know the key factors to keep an eye out for such as slight changes in shape or saturation due to a natural storm event. Rainfall, however, is not the only culprit: Earthquakes also are capable of causing severe destruction to slopes. Just being a little proactive can prevent many structural disasters – and could possibly save people from being seriously injured.

Why plant different species on a freshly compacted soil slope?

With their roots, plants are able to hold soils together against the impacts of heavy rains, winds, and other forms of erosion. As erosion and scouring can be a major source for undermining slope integrity, ...

How does rock integrity affect slope?

Rock Integrity. The integrity of rock located below upper soil layers can greatly affect the overall integrity of the slope once damaged. Sometimes the bedding planes in rock can be layered with inadequate materials that react differently as water content levels change.

How to ensure slope stability?

To ensure slope stability in constructed soil slopes, one common method is to take soil core samples, determine the stratigraphic layout of the soils, and then cut benches into the weaker soil. Next, a more stable and uniform soil type can be placed overtop to promote slope stabilization.