What is a safe slope?

All simple slope excavations 20 feet or less in depth shall have a maximum allowable slope of 3/4:1. Simple Slope Exception: Simple slope excavations which are open 24 hours or less (short term) and which are 12 feet or less in depth shall have a maximum allowable slope of 1/2:1.

What is maximum allowable slope?

Maximum allowable slope means the steepest incline of an excavation face that is acceptable for the most favorable site conditions as protection against cave-ins, and is expressed as the ratio of horizontal distance to vertical rise (H:V).

What is the proper slope for excavation?

The slope angle for a Type B excavation is a 1:1 ratio or a 45-degree angle. For every foot of depth, the sides of the excavation must slope back 1 foot.

What is the maximum allowable slope for stable rock?

20 ft deep shall not exceed the maximum allowable slope (expressed as horizontal:vertical) for the soil/rock type indicated below: ▪ Stable Rock shall not exceed a vertical slope (90 degrees). Type A Soils shall have a maximum allowable slope of 3/4:1 (53 degrees).

How do you stabilize a 2 1 slope?

Controls can include: subsurface drains or a layer of crushed rock at the toe of the slope. Slopes steeper than 2:1 will usually require special stabilization measures such as a crushed rock or riprap layer, crib wall or revetment.

Slope stability: failure definition and factor of safety

What is the minimum slope required if sloping is used to make the trench safe for occupancy?

OSHA requires type C soil to be sloped at 1½H:1V and it cannot be benched. This means that the slope must be cut back 1½ ft horizontally for every 1 ft of depth.

What slope is unstable?

unstable slope means a naturally occurring slope with a gradient between 15 and 39 percent (dividing the vertical rise by the horizontal extent), with a total vertical relief greater than 10 feet, where springs or ground water seepage is present on the slope.

What is factor of safety for slope?

The slope stability safety factor refers to the ratio of the soil shear strength to the shear stress of a possible sliding surface in the slope.

What is the minimum factor of safety for slope stability?

For general slope stability analysis of permanent cuts, fills, and landslide repairs, a minimum safety factor of 1.25 should be used.

How do you slope a safety trench?

The OSHA guidelines for trench sloping are generally pretty simple: for trenches less than 20 feet in depth, the slope needs to be cut back to 1.5 times wider than the depth of the trench. However, it can get much more complicated from there. Trenches over 20 feet in depth, require a licensed engineer.

What is the OSHA standard for excavation?

OSHA requires employers to provide ladders, steps, ramps, or other safe means of egress for workers working in trench excavations 4 feet (1.22 meters) or deeper. The means of egress must be located so as not to require workers to travel more than 25 feet (7.62 meters) laterally within the trench.

What is the minimum allowable slope of the ground that is immediately adjacent to a foundation wall?

The ground immediately adjacent to the foundation shall be sloped away from the building at a slope of not less than one unit vertical in 20 units horizontal (5-percent slope) for a minimum distance of 10 feet (3048 mm) measured perpendicular to the face of the wall.

What is a 10 1 slope?

In geometry, 1 in 10 means for every ten units of horizontal distance crosses there is 1 unit of vertical drop or rise. The angle of tan is used to measure this value of slope. Let x be the angle to be used for tan.

What is a 2 1 slope?

A 2:1 slope is also 50% slope, and a 1:1 slope is 100% slope. Slope can be easily measured in a yard using two wooden stakes, a piece of. nylon cord or twine, and a hanging bubble level (use schematic below for. reference).

What type of soil must never be benched?

Type C soil cannot be benched.

How do you determine the stability of a slope?

Stability is determined by the balance of shear stress and shear strength. If the forces available to resist movement are greater than the forces driving movement, the slope is considered stable. A factor of safety is calculated by dividing the forces resisting movement by the forces driving movement.

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.

What are 5 causes of slope failure?

What is steep slope?

adjective. A steep slope rises at a very sharp angle and is difficult to go up. steeply adverb [ADVERB with verb]

What are the three types of slope failures?

How do you analyze a slope?

To calculate percent slope, divide the difference between the elevations of two points by the distance between them, then multiply the quotient by 100. The difference in elevation between points is called the rise. The distance between the points is called the run. Thus, percent slope equals (rise / run) x 100.

How deep can a trench be before shoring is required?

Trenches 5 feet (1.5 meters) deep or greater require a protective system unless the excavation is made entirely in stable rock. If less than 5 feet deep, a competent person may determine that a protective system is not required.

What is the maximum slope measured from the vertical allowed for a spoil pile?

The spoil pile must be sloped at an angle not steeper than one horizontal to one vertical, or 450 measured from the horizontal .

What is shoring sloping?

Shoring- A structure that supports the sides of an excavation and protects against cave-in. Shall: Mandatory requirement Should: Optional requirement Sloping – Cutting of the edge back in inclined manner that it will not slide in the trench or excavated area.