IMPACT ~ Breach Physical Modelling Review of Modelling Work Undertaken So Far

Download IMPACT ~ Breach Physical Modelling Review of Modelling Work Undertaken So Far

Post on 01-Apr-2015

213 views

Category:

Documents

1 download

Embed Size (px)

TRANSCRIPT

<ul><li>Slide 1</li></ul> <p>IMPACT ~ Breach Physical Modelling Review of Modelling Work Undertaken So Far... Slide 2 IMPACT - Breach Physical Modelling Summary Objectives General approach and facilities Scaling Controlling / assessing soil properties Data collection Test programme Test results so far... Slide 3 IMPACT - Breach Physical Modelling Objectives To provide lab data through which: Field test data may be compared and scaling issues (between field and lab) analysed Breach formation behaviour may be extrapolated from field test data via multiple lab tests showing effect of variation in: geometry / sediment size &amp; grading / construction / embankment condition Additional data for numerical model comparison and validation Slide 4 IMPACT - Breach Physical Modelling General approach and facilities: General approach: Programme of 25 lab tests 9 Autumn 2002 8 Spring 2003 8 Autumn 2003 Scaling field tests at 1:10 (trying to balance scaling effects) Using large scale laboratory facilities to extend data sets as much as possible Slide 5 IMPACT - Breach Physical Modelling General approach and facilities: Facilities: Using a large flume (50m x 10m wide) Peak discharge &gt;1m3/s (but limited) Automated logging of: water levels flow into flume pressure beneath embankment u/s vertical velocity profile u/s face digital photo shots d/s face video footage Slide 6 Breach Formation Physical Modelling Flume (earlier model) Slide 7 Breach Formation Physical Modelling Flume (dimensions) 10m 50m 0.8m Flow upto 1.25m 3 Slide 8 IMPACT - Breach Physical Modelling Flume Slide 9 Slide 10 IMPACT - Breach Physical Modelling Scaling Range of approaches considered Mobile bed modelling Sediment entrainment / fall velocities Reynolds, Froudian etc. For non cohesive, considering different approaches, concluded straight geometric scaling 1:10 Review of scaling later within uncertainty assessment Slide 11 IMPACT - Breach Physical Modelling Scaled Sediment Slide 12 Slide 13 Slide 14 IMPACT - Breach Physical Modelling Controlling and Assessing Soil Properties In order to ensure that field and lab tests are similar we need to consider: Soil type grading permeability strength cohesion Construction properties: density moisture content Slide 15 IMPACT - Breach Physical Modelling Controlling and Assessing Soil Properties Soil type (grading, strength etc.) is determined through lab analysis of the sample. Properties analysed include: grading permeability proctor Slide 16 IMPACT - Breach Physical Modelling Controlling and Assessing Soil Properties This data permits plotting of the density moisture curve to show optimum compaction. During construction, optimum compaction is aimed for. During construction density readings are taken (nuclear density probe) at 9 locations across the bank and at three levels. This permits the degree and consistency of compaction to be identified. (Test#1 1.79g/cm 3 ; Test#2 1.76g/cm 3 ) Slide 17 IMPACT - Breach Physical Modelling Density Measurement - Nuclear Probe Slide 18 IMPACT - Breach Physical Modelling Data Collection Automated logging of: water levels flow into flume pressure beneath embankment u/s vertical velocity profile u/s face digital photo shots d/s face video footage Slide 19 IMPACT - Breach Physical Modelling Data Collection Slide 20 Slide 21 Slide 22 IMPACT - Breach Physical Modelling Test Programme Programme of 25 lab tests 9 Autumn 2002 Non cohesive Prior to Autumn 2002 field work 8 Spring 2003 Cohesive Prior to Autumn 2003 field work 8 Autumn 2003 TBA (piping?) Post Autumn 2003 field work Slide 23 IMPACT - Breach Physical Modelling Test Programme - Autumn 2002 Lab Test#1Trial / test experiment Lab Test#2Steeper sediment grading - D 50 Field Test#2 Lab Test#3Repeat Lab Test#2 Lab Test#4Breach location (initiate at side of channel) Lab Test#5Scaled grading of Field Test#2 Lab Test#6Vary geometry(Crest 2m, Slope 1:2) Lab Test#7Vary geometry(Crest 3m, Slope 1:2) Lab Test#8Steeper grading, different D 50 Lab Test#9SS Seepage or 2 nd D 50 variation Slide 24 IMPACT - Breach Physical Modelling Test Programme - Spring 2003 Programme to be agreed. Objectives to: Integrate with Norwegian field work Integrate with other European and US experimental work Slide 25 IMPACT - Breach Physical Modelling Test results so far... Tests 1-5 completed (probably!) Tests 6-9 within next 2-3 weeks Steady state seepage an issue Data from first tests yet to be processed, however photo and video footage is available... Slide 26 IMPACT - Breach Physical Modelling Test results so far... Breach features noted in Tests 1-3: (Seepage and slumping of d/s face) Initial vertical cut through bank Rapid cut back of d/s face in line with slot Likely significant erosion below bed level Vertical sides of breach Side cracking and slumping Upstream slope (face) remains in place as weir for considerable time (flow control) Slide 27 IMPACT - Breach Physical Modelling Test results so far... Still photo series Test 2Test 2 Still photo series Test 3Test 3 AVI footage Test 2Test 2 AVI footage Test 3Test 3 </p>