Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic...

17
Soils Part 2: Working through examples

Transcript of Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic...

Page 1: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,

Soils Part 2: Working through examples

Page 2: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,

Engineering Properties of Soils

• Soil Mechanics– Algebraic relationships

• Vm, Va, Vv, Vw, Vs

• Wm, Wa, Ww, Ws

– Examples• Solution for water content (w)

• Solution of void ratio (e)

• Effect of water table level on effective pressure

Page 3: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,

Phase Diagram

Page 4: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,
Page 5: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,
Page 6: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,

Engr. Properties of Soils: Example # 2

Page 7: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,

Engineering Properties

• Corrosion– Chemical decomposition– Affects fixtures such as culverts, cables and

pipes– Depend on soil resistivity (low R-values have

high corrosion potential)

• Ease of excavation– Procedures for removal during construction– Excavation vs. blasting (definition)

Page 8: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,

Expansive Soils

Expansion results from changes in cation hydration envelopes; improves when Ca+2 replaces Na+1

Pure Montmorillonite may expand up to 15x original volume!

Page 9: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,

Engineering Properties

• Shrink-swell potential (expansive)– >3% volume increase potentially hazardous– Gain or loss of water (PI)– Clay mineralogy (smectites)/sulfate soils– About $3 billion in losses/yr. (Most expensive)

– Common problem in parts of Florida– Treatments

• Avoidance, Removal (Nationwide building)• Slaked/hydrated lime (I-75 at Payne's Prairie)• Portland Cement (sandy soils)• Calcium chloride

Page 10: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,

Engineering Properties of Soils

Page 11: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,

Auger for drilling Footings for Stadium addition,Sept. 13, 2001

Engineering Propertiesof Soil

Page 12: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,

Rates of Soil Erosion (Universal Soil Loss Equation)

Sediment Pollution -The greatest source of pollution.

Land Use and Environmental Problems of Soils– Urbanization

• Increased erosion during construction• Increased run-off after construction• Increased stream erosion due to decreased sediment load and increased run-

off

– Off-Road Vehicles (snowmobiles, mountain bikes)• Dunes and forests • Damaging vegetation

Page 13: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,

Land Use Changes

Page 14: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,

Soil Pollution

• Times Beach Missouri(dioxin)• Alachua and High Springs (EDB)• Cabot Carbon Superfund site• School on landfill• Inadvertent or deliberate• Treatment

– On-site– Excavation– Bioremediation

Page 15: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,

Desertification• Symptoms

– Declining water table– Salinization of soil and water– Decrease in surface drainage– High rates of soil erosion– Damage to native vegetation

• Minimization– Protect and improve arable land– Protect from overgrazing; increase restoration efforts– Apply soil conservation practices– Appropriate technology (less intense)

Page 16: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,

Desertification

Page 17: Soils Part 2: Working through examples. Engineering Properties of Soils Soil Mechanics –Algebraic relationships V m, V a, V v, V w, V s W m, W a, W w,

Soil Surveys and Land-Use Planning

• Soils affect the best use of land• Properties are mappable features• Geohazards may be mapped or imaged• Geographic Information Systems

– Features identify "best uses" area – Exclude areas(paleo-sinkholes at landfill site)

• Must be done on a large enough scale to be effective (satellite, SLAR, LIDAR)