1 / 38

EARTH EROSION PROCESSES

EARTH EROSION PROCESSES. __________________________ SITES 2005 INTEGRATED DEVELOPMENT ENVIRONMENT for WATER RESOURCE SITE ANALYSIS. OBJECTIVE. Introduce erosion theory related to earthen auxiliary spillways. BASIC EROSION PROCESSES RELEVANT TO EARTHEN AUXILIARY SPILLWAYS.

umeko
Download Presentation

EARTH EROSION PROCESSES

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. EARTH EROSION PROCESSES __________________________ SITES 2005 INTEGRATED DEVELOPMENT ENVIRONMENT for WATER RESOURCE SITE ANALYSIS

  2. OBJECTIVE Introduce erosion theory related to earthen auxiliary spillways

  3. BASIC EROSION PROCESSES RELEVANT TO EARTHEN AUXILIARY SPILLWAYS • SURFACE DETACHMENT VEGETATED EARTH CHANNEL FLOW BARE EARTH CHANNEL FLOW IMPINGING JET FLOW • HEADCUT ADVANCE

  4. SURFACE DETACHMENT

  5. er tc te

  6. SURFACE DETACHMENT . r = kd (e - c)a . r = the rate of detachment kd = coefficient of detachment e = effective stress c = critical tractive stress a = exponent (~ 1)

  7. EFFECTIVE STRESS • VEGETATION • e= ds(1-Cf) (ns/n)2

  8. EFFECTIVE STRESS • BARE EARTH • e=ds

  9. EFFECTIVE STRESS • AT THE HEADCUT • e= dc 0.011(H/dc)0.582 dc H e

  10. APPLICATION OF DETACHMENT RATE EQUATION IN VEGETATION e=  ds(1-Cf) (ns/n)2 . r = kd (e - c)

  11. ef te

  12. DETACHMENT RATE EQUATION gd 5.66gw ( )3.10 kd = exp[ -0.121(c%)0.41 ] gw gd kd = detachment rate coefficient gd = dry unit weight gw = unit weight of water c%= clay percentage

  13. t

  14. MASS MOVEMENT

  15. HEADCUT MIGRATION dx/dt = C (A - Ao) dX/dt = rate of headcut migration, C = material-dependent advance rate coefficient, A = hydraulic attack, and Ao = material-dependent threshold.

  16. HEADCUT MIGRATION RATE dX/dt

  17. HYDRAULIC ATTACK A = (q q H

  18. MATERIAL-DEPENDENT PARAMETERS AO & C are a function of Kh = headcut erodibility index

  19. HEADCUT ERODIBILITY INDEX, Kh Kh= MS x Kb x Kd x JS MS= material strength number of the earth material, Kb= block or particle size, Kd= discontinuity or inter- particle bond shear strength number, and Js= relative ground structure number.

  20. Condition of the Joints • Rough or smooth • Open or closed • Gap size • material in joints Block size Kb Kd Orientation to the flow Js

  21. Kh = 0.01 DESCRIPTION: SM, very loose sand with little bonding SITE: Buck and Doe Run 33, Missouri COMMENT: Eroding material in spillway breach: deep deposit

  22. Kh = 0.17 DESCRIPTION: CL , stiff SITE: Rush Creek 12R, Oklahoma COMMENT: Eroding material in headcut face.

  23. Kh = 0.5 DESCRIPTION: Disintegrated shale SITE: West Fork Point Remove 5, Arkansas COMMENT: Eroding material in gully bank.

  24. Kh = 20 DESCRIPTION: Jointed sandstone SITE: West Fork Pint Remove 5, Arkansas COMMENT: Material remaining below surface erosion. Some minor detachment by flow.

  25. Kh = 35000 DESCRIPTION: Massive rock (ryolite) SITE: Painted Rock Dam, Arizona COMMENT: Spillway outlet, negligible erosion.

  26. [ _ 189 Kh1/2exp(-3.23/ln(101Kh)) ]1/3 Kh> 0.01 AO = 0 Kh< 0.01 AND - 0.79 ln(Kh) + 3.04 Kh< 18.2 C = 0.75 Kh > 18.2 _

  27. Kh for MULTIPLE MATERIALS { } hi ln( Kh )i Kh = exp hi h1 Kh1 htotal h2 Kh2 h3 Kh3

More Related