Questions and Answers of Mechanics

The following information was obtained from laboratory tests on specimens from a completely saturated sample of clay:(a) The sample had in the past been pre-compressed to at least 200 kPa.(b) A
Triaxial tests were performed on undisturbed samples from the same depth of organic clay whose pre-consolidation load, determined from consolidation tests, was in the range 90 to 160 kPa. The
An un-drained triaxial compression test was performed on a saturated sample of normally consolidated clay. The consolidation pressure was 100 kPa. The specimen failed when the principal stress
Triaxial compression tests were run on specimens from a large undisturbed block sample of clay. Data are given below. Tests 1 through 4 were run so slowly that complete drainage may be assumed. In
A CU triaxial test is performed on a cohesive soil. The effective consolidation stress was 750 kPa. At failure, the principal stress difference was 1250 kPa, and the major effective principal stress
Suppose another specimen of the soil in the preceding problem developed a major effective principal stress of 2200 kPa at failure. What would Skempton's pore pressure coefficient A at failure be, if
Two samples of a slightly over-consolidated clay were tested in triaxial compression, and the following data at failure were obtained. The pre-consolidation stress for the clay was estimated from
Two identical specimens of soft saturated normally consolidated clay were consolidated to 150 kPa in a triaxial apparatus. One specimen was sheared drained, and the principal stress difference at
A clay sample is hydrostatically consolidated to 1.0 MPa and then sheared un-drained. The (σ1 - σ3) at failure was also equal to 1 MPa. If drained tests on identical samples gave ∅' = 22o,
The following data were obtained from a CU test with pore pressures measured on an undisturbed specimen of sandy silt. The consolidation pressure was 850 kPa and the specimen was sheared in axial
A 2-m-thick fill is constructed at the surface of the soil profile of Example 6.8. If the clay is slightly over-consolidated, estimate the change in pore pressure at point A of Fig. Ex. 6.8.?
A soil sample is taken from the midpoint of the clay layer of Example 6.8-that is, from a depth of 6 m. If the pore pressure parameter Au for unloading is 0.90, estimate the effective vertical and
A sample of normally consolidated clay is removed from -10 m below the ground surface. The effective vertical overburden stress is 250 kPa, and Ko is 0.8. If the pore pressure parameter due to
A normally consolidated clay has a ∅' of 30o. Two identical specimens of this clay are consolidated to 200 kPa in a triaxial cell. Predict the maximum and minimum possible axial stresses in the
The effective stresses at failure for three identical triaxial specimens of an over-consolidated clay are shown in Fig. P13.49. Plot the Mohr circles at failure and determine âˆ…' and c'.
Three identical specimens (same e, w) of a clay are normally consolidated and sheared consolidated-drained (CD) in both compression and extension. The stresses at failure for the three specimens are
A series of conventional triaxial compression tests were conducted on three identical specimens of a saturated clay soil. Test results are tabulated below.(a) Sketch the total and effective stress
Assume that the induced pore pressures at failure for Problem 13.51 were: specimen A, - 15 kPa; specimen B, -40 kPa; and specimen C, -80 kPa; and that everything else was the same. Now do parts (a)
The following data were obtained from a conventional triaxial compression test on a saturated (B = 1), normally consolidated simple clay (Ladd, 1964). The cell pressure was held constant at 10 kPa,
A conventional triaxial compression (AC) test was conducted on a saturated sample of over-consolidated clay, and the following data, normalized with respect to the effective confining pressure, were
A consolidated-un-drained triaxial compression test was conducted on an undisturbed specimen of sensitive Swedish clay. The initial conditions were as shown in Fig. P13.56a.The stress-strain and pore
If an LE test were conducted on a sample of Swedish clay identical to that tested in Problem 13.56, predict the pore pressure versus strain response of the clay. What are uf and A f? What is ∅T?
The data shown in Fig P13.58 are obtained from several CU tests on a saturated clay which has an OCR of 10 and a pre-consolidation stress of 800 kPa. It is assumed that these results are valid for
A series of CU compression tests on simple clay (Ladd, 1964) provided the following test results:(a) In an axial compression test, if Ïƒ'c = 200 kPa, determine qf, pf, and p'f.(b) Find âˆ…' and
A soil sample is subjected to an initial equal-all-around hydrostatic state of stress of 50 kPa. Sketch the stress paths for the loading conditions when (a) σ h remains constant and σ v increases
Figure P13.60 shows normalized data from an axial compression (AC) triaxial test and a lateral compression (LC) triaxial test on saturated simple clay (Ladd, 1964). Make the appropriate calculations,
For the oil tank problem in Chapter 10 (Problem 10.16), plot the complete total, total-uo, and effective stress paths due to construction and filling of the tank for an element under the centerline
What is the maximum safe height of the embankment for Examples 13.4 and 13.8? Plot a graph of factor of safety versus height of the embankment?
A CU extension test was performed on a normally consolidated specimen using axial extension. The strength ratio was -0.280, and the effective failure angle, α' = 26.5 deg. Find A f.?
The following data was obtained from CD direct shear tests on NC and OC specimens of a low plasticity clay. The OC specimens were originally consolidated to 600 kPa, then rebounded to obtain the OCRs
Given the same initial conditions as for Problem 13.6, draw the stress paths for loading when (a) ∆σ h = ∆σ v/3 (b) ∆σ h = ∆σ v/4.?
Undisturbed piston samples of grey silty Chicago clay were obtained from a depth of -9 m as shown in the soil profile in Fig. P13.70a, for laboratory testing. Different types of strength tests as
A triaxial sample of loose sand is tested in lateral extension (LE) (see Fig. 13.7). The sample is first consolidated non-hydrostatically, with σ1 = 15 kPa and σ3 = 10 kPa. The sample is then
Another sample of the same sand tested in Problem 13.8 is tested in lateral compression (LC). Complete parts (a) and (b) requested in Problem 13.8 for this test.

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