Geology and Construction - Dams

Geology

it is one of the most important factors in construction since construction takes place either at or below the ground surface

Geology

it has an influence on most construction operations because it helps determine their nature, form and cost

Open Excavation

it refers to the removal of material, within certain specified limits, for construction purposes

Stability of Slopes

it is a critical factor in open excavation

Stability Analysis

should determine under what conditions a proposed slope will remain stable

Instability in a soil mass

it occurs when slip surfaces develop and movements are initiated within it

Method of Excavation

it is determined largely by the geology of the site, however, consideration also must be given to the surroundings

Rippability

it depends on intact strength, fracture index and abrasiveness, that is, strong, massive and abrasive rocks do not lend themselves to ripping

Seismic Refraction

the most common method for determining rippability is by ________

Digging

the diggability of ground is of major importance in the selection of excavating equipment and depends principally upon the intact strength of the ground

Groundwater

frequently represents one of the most difficult problems during excavation, and its removal can prove costly

Fences

supported by rigid posts can contain small rockfalls, but larger heavy duty catch fences are required for larger rockfalls

Rock Traps

in the form of a ditch and/or barrier can be installed at the foot of a slope

Benches on a slope

also may act as traps to retain rock falls, especially if a barrier is placed at their edge

Dentition

it refers to masonry or concrete infill placed in fissures or cavities in a rock slope

Rock Bolts

it may be up to 8 m in length with tensile working loads of up to 100 kN

Rock Bolts

they are put in tension so that the compression induced in the rock mass improves shearing resistance on potential failure planes

Light Steel Section or Steel Mesh

it may be used between bolts to support the rock face

Rock Anchors

are used for major stabilization works, especially in conjunction with retaining structures

Rock Anchors

they may exceed 30 m in length

Gunite or Shotcrete

frequently is used to preserve the integrity of a rock face by sealing the surface and inhibiting the action of weathering

Gunite or Shotcrete

the are pneumatically applied mortar or concrete, respectively

Coatings

may be reinforced with wire mesh and used in combination with rock bolts

Coatings

heavily fractured rocks may be grouted in order to stabilize them

Reinforced Earth Walls

are constructed by erecting a thin front skin at the face of the wall at the same time as the earth

Cribs

may be constructed of precast reinforced concrete or steel units set up in cells that are filled with gravel or stone

Gabions

contains of strong wire mesh surrounding placed stones

Concrete Buttresses

occasionally have been used to support large blocks of rock, usually where they overhang

Drainage

it is generally is the most applicable method for improving the stability of slopes of for the corrective treatment of slides, regardless of type, since it reduces the effectiveness of one of the principal causes of instability, namely, excess pore water pressure

Drainage

the most likely zone of failure must be determined so that the extent of the slope mass that requires drainage treatment can be defined

Dams

can be divided into two major categories according to the type of material with which they are constructed, namely, concrete dams and earth dams

Concrete Dams and Earth Dams

Dams can be divided into two major categories according to the type of material with which they are constructed, namely, ____________________

Gravity Dam

it is a rigid monolithic structure that is usually straight in plan, although sometimes it may be slightly curved

Gravity Dam

its cross section is roughly trapezoidal

Gravity Dam

it can tolerate only the smallest differential movements, and their resistance to dislocation by the hydrostatic pressure of the reservoir water is due to their own weight

Arch Dam

consists of a concrete walls, of high-strength concrete, curved in plan, with its convex face pointing upstream

Arch Dam

are relatively thin walled and lighter in weight than gravity dams

Arch Dam

they stand up to large deflections in the foundation rock, provided that the deflections are uniformly distributed

Buttress Dam

provide an alternative to other concrete dams in locations where the foundation rocks are competent

Buttress Dam

consists principally of a slab of reinforced concrete that slopes upstream and is supported by several buttress whose axes are normal to the slab

Earth Dam

are embankments of earth with an impermeably core to control seepage

Earth Dams

this usually consists of clayey material

Rockfill Dam

usually consists of three basic elements

Loose Rockfill Dump

which forms the bulk of the dam