Foundation Engineering Basics

<p>Pile (D)</p> Signup and view all the answers

<p>Ensuring adequate foundation depth (C)</p> Signup and view all the answers

<p>Local weather patterns (C)</p> Signup and view all the answers

<p>Maintaining a safety margin in design (B)</p> Signup and view all the answers

<p>Plastic sheeting (C)</p> Signup and view all the answers

<p>To identify any existing utilities that may pose hazards (C)</p> Signup and view all the answers

<p>Excavations provide a better view of soil layers and contamination (C)</p> Signup and view all the answers

<p>Shallow investigation borings (B)</p> Signup and view all the answers

<p>Rotary drilling (C)</p> Signup and view all the answers

<p>Soil consistency (D)</p> Signup and view all the answers

<p>They must be familiar with both tasks and equipment used (D)</p> Signup and view all the answers

<p>Conduct pre-drilling if necessary (B)</p> Signup and view all the answers

<p>When contamination is distributed unevenly, like in landfills (A)</p> Signup and view all the answers

<p>Change in void ratio and material alteration (A)</p> Signup and view all the answers

<p>2 x the least lateral plan dimensions of the building or 10 m below lowest building elevation (D)</p> Signup and view all the answers

<p>Average grain size distribution (C)</p> Signup and view all the answers

<p>High-rise structures with small plan dimensions (D)</p> Signup and view all the answers

<p>Recovering undisturbed soil samples (B)</p> Signup and view all the answers

<p>2B to infinity (A)</p> Signup and view all the answers

<p>Base shear resistance and settlements (D)</p> Signup and view all the answers

<p>Settlement criteria (C)</p> Signup and view all the answers

<p>Vertical accumulation of soil particle movements (B)</p> Signup and view all the answers

<p>Time-dependent nature of settlements (B)</p> Signup and view all the answers

<p>They are more cost-effective (A)</p> Signup and view all the answers

<p>Vertical values often differ significantly from horizontal values (C)</p> Signup and view all the answers

<p>Soft strata could lead to failure of the structure (B)</p> Signup and view all the answers

<p>Ultimate bearing capacity (A)</p> Signup and view all the answers

<p>Elastic properties of soil subjected to shear (D)</p> Signup and view all the answers

<p>Site-specific engineering judgment is necessary (A)</p> Signup and view all the answers

<p>Make the best estimate of qo. (C)</p> Signup and view all the answers

<p>By seven percent. (D)</p> Signup and view all the answers

<p>It is the depth to where a hard stratum is encountered. (B)</p> Signup and view all the answers

<p>To increase load-bearing capacity. (C)</p> Signup and view all the answers

<p>It specifically targets increased soil performance effectively. (D)</p> Signup and view all the answers

<p>The base dimensions into contributing rectangles. (B)</p> Signup and view all the answers

<p>Vibration. (C)</p> Signup and view all the answers

<p>10 (D)</p> Signup and view all the answers

<p>Overestimating the computed values. (B)</p> Signup and view all the answers

<p>About 7 days. (A)</p> Signup and view all the answers

<p>Consolidation settlement. (C)</p> Signup and view all the answers

<p>0.8 to 1.2. (D)</p> Signup and view all the answers

<p>Time-dependent factors. (A)</p> Signup and view all the answers

<p>Intensity of contact pressure. (A)</p> Signup and view all the answers

<p>To depend on the ratio of L’ to B’, thickness, and other properties. (C)</p> Signup and view all the answers

<p>Leaning Tower of Pisa. (B)</p> Signup and view all the answers

A foundation that is relatively shallow, with a depth generally less than the width (D/B < 1).

A shallow foundation supporting a single column.

A shallow foundation used to support multiple columns.

A foundation that extends significantly into the ground, having a depth greater than 4 times its width (D/B > 4).

A deep foundation that distributes load vertically, like spread footings but deeper.

Considerations for foundation design include building purpose, loading expectations, soil conditions, construction methods, and cost.

Foundation depth must prevent lateral soil movement and be below zones affected by seasonal changes (freezing/thawing).

A structure built to hold back soil or other materials in a specific shape, instead of relying on gravity alone.

Continuous-flight augers with rotary drills are a common method of soil exploration in North America and Europe.

Verify absence of utilities (gas, electric, pipes), conduct utility surveys, and ensure personnel familiarity with tasks and protective equipment.

Soil borings up to 3-4 meters deep used to identify contamination in the upper soil layers and surface aquifers.

Borings deeper than 4-5 meters, probing deeper soil layers and groundwater for contamination.

Preferred method for close-to-surface soil sampling, advantageous for unevenly distributed contamination.

Drilling rigs, portable augers, percussion gouges, and hand augers are used for soil borings.

Hand augers, portable motor augers, and percussion gouges, usually used for shallow soil borings with a depth of 3-4 meters, dependent on soil consistency.

A survey for gas, electric, steam/hot water lines to ensure safe drilling location.

The downward movement of soil under applied load, caused by particle rearrangement and deformation.

The difference in stress on soil before and after applying a load, causing settlement.

The area beneath the loaded surface where the soil is affected by the applied load, leading to settlement.

The ratio of the volume of voids (empty spaces) to the volume of solid particles in the soil.

Temporary deformation of soil particles that mostly recover when the load is removed.

A material that, though not truly elastic, is modeled with elastic parameters for settlement calculations.

Measures how much a soil deforms under a certain applied stress.

Difficulty in obtaining reliable values for soil parameters and determining the accurate stress profile under the applied load.

Borings should extend below the depth where foundation load stress significantly increases. A general rule is 2 times the least building width or 10 meters below the lowest building element, though adjustments are required for varying building types.

Soil's ability to support structure loads without shear failure or unacceptable settlements.

A failure of the soil where there is a sliding or crumbling of the supporting surface.

The maximum load a soil can safely support without unacceptable settlement.

Standards that dictate how much a structure can sink before it becomes problematic.

The soil's ability to resist movement and sliding of the structure due to external forces

Borings are crucial for evaluating the suitability of the soil for supporting proposed structures, to locate bedrock or strong soil, and to ensure adequate safety margins in construction.

The ratio of measured to computed settlement in a foundation, typically ranging from 0.5 to 2+, with most values between 0.8 and 1.2.

Settlements are categorized into two types: immediate (occurring quickly) and consolidation (happening over time, months to years).

An extreme example of consolidation settlement, the tower's uneven subsidence over centuries demonstrates the potential of this time-dependent process.

These analyses are used for fine-grained soils with low saturation and coarse-grained soils with high permeability.

Applied to saturated or nearly saturated fine-grained soils, these analyses estimate both settlement and its duration.

A function solely of the ratio of r/z, representing the influence of the base's radius and depth on settlement.

Calculates the settlement of a rectangular base on an elastic half-space, taking into account pressure, base dimensions, influence factors, and soil properties.

Factors like base dimensions (L'/B'), stratum thickness (H), Poisson's ratio (μ), and embedment depth (D) significantly affect settlement.

The H equation is accurate for flexible foundations on a half-space, where the foundation deflects under load. Rigid foundations have a slightly lower settlement (about 7% less).

For rigid foundations, the settlement is uniform but may tilt. The settlement is approximately 7% less than that of a flexible foundation.

When dealing with a rigid base, reduce the Is factor by approximately 7% (Isr = 0.931 Is) to account for the smaller settlement.

The depth at which the stratum causes settlement is not H/B to infinity but either 5B (B is the base's least lateral dimension) or the depth of a hard stratum.

Consider a stratum 'hard' when its elastic modulus (Es) is 10 times larger than the adjacent layer's Es.

H/B' ratio is calculated as H/B' = H/ (B/2) for the center of the base and H/B' = H/B for the corner of the base.

Soil improvement aims to enhance soil properties by increasing load-bearing capacity, reducing settlement, and mitigating liquefaction risk.

Techniques include compaction, vibration, and adding stronger materials to enhance soil properties. The choice depends on the soil type.