Ground Improvement Techniques

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson
Download our mobile app to listen on the go
Get App

Questions and Answers

The method of ______ has been used for thousands of years to provide tensile reinforcement to clayey materials in buildings, representing an early form of ground modification.

wattle and daub

The process of adding straw to clay and ______ improved the strength properties of the clay, leading to a durable building material that has been used for centuries.

baking it in the sun

According to Moseley and Kirsch, all ground improvement techniques enhance soil characteristics to align with project goals, like boosting density and ______ for enhanced stability.

shear strength

As noted by Schaefer et al., ground improvement aims to alter foundation conditions or earth structures to achieve better performance under specified design and ______ conditions.

<p>operational loading</p> Signup and view all the answers

Compaction is a first-order improvement that directly increases the ______ of soil, enhancing its stability.

<p>density</p> Signup and view all the answers

An increase in soil density due to compaction leads to second-order effects such as increased strength and reduced ______, improving the soil's load-bearing capabilities.

<p>compressibility</p> Signup and view all the answers

Improvements in soil leading to increased bearing capacity and reduced settlement represent ______ order effects, further enhancing structural stability.

<p>third</p> Signup and view all the answers

Instead of ground improvement, an alternative is to consider ______ or a different area within the same site, leveraging more suitable ground conditions.

<p>finding an alternative site</p> Signup and view all the answers

An economical alternative to ground improvement involves excavating unsuitable soils and replacing them with more suitable ______, ensuring a stable base.

<p>materials</p> Signup and view all the answers

The use of ______, such as piles or drilled shafts, is a method to transfer loads to deeper, more competent bearing materials, bypassing shallow unstable layers.

<p>deep foundations</p> Signup and view all the answers

Adapting structures through ______ to accommodate site conditions is a strategic approach that minimizes the impact of less-than-ideal soil.

<p>structural redesign</p> Signup and view all the answers

Evaluating ground improvement alternatives based on their ______ to increase bearing capacity and decrease settlement is crucial in structural engineering.

<p>ability</p> Signup and view all the answers

Increasing the ______ of the soil results in decreased settlement, enhancing the soil's ability to support structural loads with minimal deformation.

<p>stiffness</p> Signup and view all the answers

Boosting the ______ strength of soil increases its bearing capacity, allowing it to support heavier loads and maintain stability.

<p>shear</p> Signup and view all the answers

Decreasing soil ______ variability results in reduced differential settlement, ensuring uniform support across a structure's foundation.

<p>property</p> Signup and view all the answers

______ granular materials or cohesive materials can improve soil properties such as strength and stiffness, essential for construction.

<p>Densifying</p> Signup and view all the answers

______ can be increased through ground improvement techniques that decrease the void ratio and/or add a cohesive cementing component.

<p>Shear strength</p> Signup and view all the answers

Compressibility depends on the nature of the ______ and the initial stress state of the soil; it is not a unique value.

<p>load application</p> Signup and view all the answers

______ can be increased by compaction and consolidation, which are imperative when improving fundamental soil behavior.

<p>Cohesive soil stiffness</p> Signup and view all the answers

Improved ground is modified to produce a zone of reduced ______ to control detrimental effects of groundwater.

<p>permeability</p> Signup and view all the answers

Flow beneath a dam can lead to ______ and instability if not treated properly.

<p>soil particle movement</p> Signup and view all the answers

Construction projects below grade often require ______ to make sure that the site does not get flooded.

<p>construction dewatering</p> Signup and view all the answers

If loose gramual materials are subject to a dynamic load, this can cause ______ during an earth quake.

<p>liquefaction</p> Signup and view all the answers

Most common mitigation to the risk of having loose granular materials on site, is to ______ the soil, which reduces their liquefaction potential.

<p>densify</p> Signup and view all the answers

Loose granular soil deposits generally ______ in volume during an earthquake by liquefaction.

<p>decrease</p> Signup and view all the answers

Techniques to reduce liquefaction potential include both groundwater control and ______, which can be a tedious process.

<p>in situ mixing</p> Signup and view all the answers

Soils containing smectitic clays are subject to substantial volume changes in response to cycles of ______.

<p>wetting and drying</p> Signup and view all the answers

A shrink/swell behavior of expansive soils can be detrimental to both buildings and cause a ______ to fail.

<p>retaining wall</p> Signup and view all the answers

Physical and engineering properties of soils are ______, which affects it's performance when attempting to build a structure on the land.

<p>naturally variable</p> Signup and view all the answers

If the ______ varies enough from location to location; this can cause an excessive differential settlement.

<p>compressibility</p> Signup and view all the answers

Using ground improvement can modify properties of subsurface materials to provide a more ______ performance when constructing.

<p>uniform</p> Signup and view all the answers

The four defining principles to to Increasing Complexity of Ground Improvement include Control of water, Mechanical modification, Modification by additives, and Modification by inclusions or ______ .

<p>confinement</p> Signup and view all the answers

Important Principles, Engineering Considerations, and Construction Method in Ground Improvement are Compaction, Soil mixing and injection methods, Stabilization and Solidification, Grouting, Dewatering and ______ .

<p>Consolidation</p> Signup and view all the answers

You cannot “design” a ground improvement program without a full understanding of the construction means and methods, and credit for the development of ground improvement techniques lies largely with innovative ______.

<p>contractors</p> Signup and view all the answers

The water content and ______ will significantly impact the efficacy of certain ground improvement techniques; knowing the saturation is a must.

<p>degree of saturation</p> Signup and view all the answers

Flashcards

Ground Improvement

Modifying ground to enhance its properties for construction.

Wattle and Daub

An old construction technique using interwoven sticks and mud.

Improve Soil Properties

A ground improvement goal to increase density and shear strength.

Alternatives to Ground Improvement

Finding other construction options for certain site conditions.

Signup and view all the flashcards

Avoid the Site

Choosing an alternative site to build structures.

Signup and view all the flashcards

Remove and Replace

Digging out unsuitable materials.

Signup and view all the flashcards

Transfer Load to Deeper Strata

Using piles or drilled shafts for structures.

Signup and view all the flashcards

Design Structure Accordingly

Modifying structure design for expected soil behavior.

Signup and view all the flashcards

System Performance Perspective

Evaluates ground improvement alternatives for increase in capacity and decrease in settlement.

Signup and view all the flashcards

Increase Soil Stiffness

Making soil stiffer to reduce how much it sinks.

Signup and view all the flashcards

Increase Soil Shear Strength

Increasing soil's resistance to sliding or breaking.

Signup and view all the flashcards

Decrease Soil Variability

Making soil more consistent across an area.

Signup and view all the flashcards

Shear Strength

Soil's capability to withstand shear stress.

Signup and view all the flashcards

Compressibility

Soil's tendency to decrease in volume under pressure.

Signup and view all the flashcards

Hydraulic Conductivity

Soil's capacity to transmit water.

Signup and view all the flashcards

Liquefaction Potential

Loose soil loses strength when shaken.

Signup and view all the flashcards

Shrink and Swell Behavior

Soil swells when wet, shrinks when dry.

Signup and view all the flashcards

Reduction In Variability

Consistent soil properties ensure stability.

Signup and view all the flashcards

Control of Water

Altering soil by removing or controlling groundwater.

Signup and view all the flashcards

Mechanical Modification

Soil rearranged to improve its qualities.

Signup and view all the flashcards

Modification by Additives

Improving soil by adding chemicals.

Signup and view all the flashcards

Modification by Inclusions

Changing ground behavior with rigid/flexible elements.

Signup and view all the flashcards

Compaction: Shallow Methods

Surface or near-surface compaction methods to increase soil density.

Signup and view all the flashcards

Compaction: Deep Methods

Enhancing deep compaction via various methods.

Signup and view all the flashcards

Grouting

Injecting grout to enhance ground strength and reduce water flow.

Signup and view all the flashcards

Dewatering

Temporary, localized, lowering of ground water to allow construction to happen.

Signup and view all the flashcards

Importance of Contractors

When innovative contractors contribute to ground improvement.

Signup and view all the flashcards

Water Content Problems

Water degree can affect ground improvement.

Signup and view all the flashcards

Study Notes

Ground Improvement Overview

  • Ground modification is an age-old practice, seen in methods like using wattle and daub for tensile reinforcement in clay buildings, and baking straw into clay to improve strength.
  • Romans using timber as a road base is another ancient example.
  • Modern approaches include geogrids and geotextiles.
  • Ground improvement techniques enhance soil characteristics to match desired project outcomes, increasing density and shear strength to improve stability.
  • The techniques reduce soil compressibility and control groundwater flow to improve soil homogeneity.
  • Ground improvement alters site foundation conditions or project earth structures to enhance performance under design and operational loads.
  • First-order improvements, like compaction, increase soil density.
  • Second-order effects include increased strength and reduced compressibility.
  • Third-order effects include increased bearing capacity and improved liquefaction resistance.
  • Alternatives to ground improvement are: avoiding the site, replacing the soil, transferring the load and designing a structure accordingly.
  • Owner / developers can seek out alternative sites to the location of facilities.
  • Replacing unsuitable soil materials with more suitable materials, like crushed stone, are frequently used when encountering localized fill.
  • Deep foundations affect load transfer by the use of stiff structural members placed between the structure and competent bearing materials, like piles or drilled shafts.
  • Structural redesign can accommodate the site conditions.

Improvement in Soil Behavior

  • Ground improvement improves performance, improving the allowable bearing value of a structure on the supporting soils.
  • Ground improvement alternatives increase bearing capacity and decrease settlement.
  • Increases in soil stiffness can decrease settlement
  • Increases in soil shear strength can increase bearing capacity
  • Decreasing soil property variability can decrease differential settlement.
  • Densifying granular or consolidating cohesive materials can increase soil strength and stiffness.
  • Ground improvement enables increased shear strength via techniques that decrease the void ratio or add a cohesive component, improving slope stability and reducing liquefaction potential.
  • Compressibility depends on the nature of the load application and initial stress state of the soil and isn't a unique value.
  • Decreased compressibility increases soil stiffness via ground improvement techniques that reduce void ratio or add a cohesive component, as well as with compaction and consolidation of cohesive soil.
  • Improved ground is modified to produce a zone of reduced permeability to control the detrimental effects of groundwater.
  • Soil particle movement (piping) and instability from flow beneath a dam can be resolved with ground modification.
  • Construction dewatering is needed for construction below grade and often below the water table.
  • During an earthquake loose granular materials below the groundwater level can be subject to liquefaction.
  • Mitigation of this risk is to densify the soils, which reduces their liquefaction potential.
  • Other techniques to reduce liquefaction potential include groundwater and in' situ mixing.
  • Smectitic clays can cause expansive soils soils undergo substantial volume changes due to cycles of wetting and drying.
  • Progressive damage to buildings or retaining walls can occur due to shrink/swell soil.
  • Physical and engineering properties of soils are naturally variable.
  • Variability can cause an excessive differential settlement for planned structures.
  • Ground improvement can modify subsurface material properties to provide more uniform performance.

Ground Improvement Techniques

  • Four defining principles in increasing complexity: control of water, mechanical modification, modification by additives and modification by inclusions or confinement.
  • Important principles include: Compaction, soil mixing, stabilization, grouting and consolidation.
  • Ground improvement programs require designs that take construction methods and means into account to be effective.
  • Credit for advances lies largely with innovative contractors, with many experts being or having been contractors.

Problems

  • Water content and degree of saturation greatly impact the efficacy of ground improvement techniques.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

More Like This

Use Quizgecko on...
Browser
Browser