LAB MANUAL 8Consolidation

LAB MANUAL 8Consolidation - CIVE 310 Soil Mechanics ONE...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
CIVE 310 Soil Mechanics ONE DIMENSIONAL CONSOLIDATION Section Assigned Due Before Lab: Read this Handout 76
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
ONE-DIMENSIONAL CONSOLIDATION PROPERTIES OF SOILS Our lab today will be about consolidation. This particular test is also known as a one- dimensional (1-D Consolidation) test because the sidewalls of the consolidometer are fixed and allow movement in only the vertical direction. Why do we do consolidation testing? We do consolidation testing to estimate the magnitude and rate of consolidation settlement, mainly for clays. What do we need to find in order to estimate consolidation settlement? 1) Calculate σ V (also seen as P 0 ), the vertical effective stress on the soil at the depth we are concerned with. We estimate this by assuming unit weights and water pressures. 2) Estimate the preconsolidation pressure, σ p (also seen as P c or P p ), which is the maximum past vertical effective stress the soil has experienced. (See Example 1) 3) Estimate C c the Compression Index (the slope of the “virgin curve”). (See Example 1) 4) Estimate C r , the Recompression Index (the slope of the “recompression curve”). (See Example 1) We can find items 2 through 4 on the e-log σ ’ (log P) curve we get from our consolidation test. 5) Estimate C v , the Coefficient of Consolidation (units = T L 2 ). Knowing the load we will place on the soil, Δσ (or Δ P) and c V , we can estimate real settlements. (See Example 1 for determination of c V ) We can find c V when we plot settlement vs. time for the load increments we apply to our soil sample. When we run a consolidation test we need to calculate the value of certain parameters: When doing this you need to recall some of the relationships you established using phase diagrams for soil: Void Ratio = s v V V e = G s = the specific gravity of the soil V = A * H (Area * Height) Then s v s v AH AH V V e = = To determine the height of the solids , recall that: w s s s G W V γ = Since volume can be expressed as: s s AH V = 77
Background image of page 2
Then: w s s s G W AH γ = Rearranging, A G W H w s s s = The initial height of the voids is: s o vo H H H = Where; H 0 is the initial sample height, H s the height of the solids The initial void ratio is: s s o H H H e = 0 The void ratio during the test
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 16

LAB MANUAL 8Consolidation - CIVE 310 Soil Mechanics ONE...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online