Undrained test

To test the coupling in the storage terms of the flow equation, five test cases were used for verification purposes 1) Isothermal Undrained Test (UTT), 2) Isothermal Drained Test (DIT), 3) Isothermal Injection Test (INI), 4) Non-isothermal Undrained Test (UNT) and (5) Non-isothermal drained test (DNT). 

Critical level of repeated loading (CLRL) from undrained tests on contractive soils. (After Sangrey, D.A. et al., Cyclic loading of sands, silts and clays. Proceedings of the ASCE Special Conference on Earthquake Engineering and Soil Dynamics, Pasadena, CA, 2, pp. 836-851,1978. Reprinted with permission of ASCE.)... 

Su is the static strength in an undrained test performed on an undisturbed sample prior to any cyclic loading... 

Ladd, C.C., and Lambe, T.W. 1963. The strength of undisturbed clay determined from undrained tests. In Symposium on Laboratory Shear Testing of Soils. ASTM 361. American Society for Testing and Materials, Philadelphia, PA, pp. 342-371. 

Triaxial tests are normally carried out on nominal 100 mm or 38 mm diameter samples with height to diameter ratio 2 1. If the height to diameter ratio is reduced to 1 1 the end platens should be lubricated Undrained tests measure undrained strength s . Drained tests, or undrained tests with measurement of pore pressure, evaluate the Mohr Coulomb parameters c and 4> Since soil strength depends on strain it is necessary to state whether the strength corresponds to the peak state, the critical state or the residual (Atkinson 1993)... 

Prior to triaxial shearing, samples may be consolidated in the apparatus to some specified state these are then known as consolidated undrained or consolidated drained tests as appropriate. Any drained or undrained test in which port pressures are measured should be consolidated before shearing... 

This result is similar to drained triaxial tests (namely, CTj = constant, dp = — (l/3)rfa(, dq= — da, dq/dp = 3). As shown in Fig. 6.2d, if an undrained stress path B-B under a consolidation pressure p g intersects with a drained stress path A-A" under a consolidation pressure a point C, the void ratio obtained from the undrained test is the same as the void ratio obtained from the drained test. We can draw these states in a space p, q, e) as illustrated in Fig.6.2f, which shows that the critical state is reached after travelling the surface referred to as the state boundary surface or Roscoe surface in both the undrained and drained tests. The line of failure is known as the critical state line (CSL). It is noted that the projection of CLS in the space p, q, e) onto the space (p, q) is given as = Mp, and the surface formed by CLS and its projection onto q, e) is referred to as Hvoslev surface, which is a failure surface found by Hvoslev in 1937 through a series of direct shear tests conducted on Vienna clay. 

CU (consolidation undrained test) method used to determine the drained and undrained shear strength parameters. The excess pore water pressure should be measmed to determine the drained characteristics. 

UU (unconsolidated undrained test) determination of undrained shear strength of a saturated soil. 

Direct shear test of soils under consolidated drained conditions Consolidated-undrained triaxial compression test on cohesive soils One-dimensional consolidation properties of soils One-dimensional consolidation properties of soils using controlled-strain loading... 

Several successive sets of creep tests were carried out between 1996 and 2002. The tests results show that the argillites has a time-dependent behaviour even in undrained conditions. That observation confirms that the time-dependent behaviour of the argilites is thus dependent on both... 

Shear Wave Velocity, Vs feet/second (m/s) Standard Penetration Test, Af [or NchIot cohesionless soil layers] (blows/foot) Undrained Shear Strength, s psf (kPa)... 

The vane shear test is a wireline tool used during the drilling operation to determine the in situ (field) undrained shear strength (S ) of soft to medium stiff clay soils. The vane shear apparatus consists of four blades placed on the end of a rod (Figure 4.20). The height (H) of the vane is standardized as twice the diameter (D). The vanes can be either rectangular or tampered. To use in the field, the vanes of the apparatus are pushed into the sediment at the bottom of the borehole. This operation produces very little soil disturbance. 

There are a wide variety of static shear strength tests as shown in Figure 6.19. These various tests differ in the manner of lateral constraint, shearing plane, and whether they are undrained/drained. 

The vane test has proved to be a very useful method of determining the undrained shear strength of soft clays and silts. It has been shown to give strength values similar to the undrained unconsolidated triaxial test (Richards, 1988). Generally, a four-bladed vane is... 

The undrained shear strength as measured by unconsolidated (UU) and consolidated undrained (CU) tests behaves in a similar pattern to the compressive strength on disturbance. The maximum undrained strength, still lower than the field strength, is usually obtained in the second quarter from the bottom of a tube sample (De Lory and Salvas, 1969). 

One of the more popular of the recent procedures based on this technique is SHANSEP (stress history and normalized soil engineering properties), which was proposed by Ladd and Foott (1974). This laboratory strength-testing procedure normalizes the undrained strength (Sy) and stress-strain characteristics with respect to the consolidation stress, Results from laboratory tests have shown that for a given OCR, the normalized stress can be used to represent the behavior of other samples with different consolidation stresses when sheared in the same type of test, at the same temperature, and at the same rate of loading. 

Beaufort Sea Clay -0.6 1.0 Jefferies et al. (1985) K as determined by pressuremeter ranged from 0.3 at surface to 2.0 at depth. K consolidated undrained triaxial tests (CKU) agreed well with CPT tests (N = 10). Very limited CKU tests. Pressuremeter tests compared very weU with UU tests... 

Note 1. ICU is the isotropically consolidated undrained triaxial test... 

The stress path generated during loading will depend upon whether the test is run allowing volume to change (drained) or not (undrained). The resulting plot of deviatoric... 

Undrained shear strength of remolded material may be estimated on the basis of the index test results. Using the theories of critical state soil mechanics (Schofield and Wroth, 1968), and assuming the undrained shear strength at the plastic limit is 70 times that at the liquid limit, it may be shown (Weaver and Schultheiss, 1990) that... 

Clay Available pile load test data in clay show that the average frictional resistance expressed as a percentage of the average undrained shear strength or average effective overburden pressure decreases with increasing pile penetration. Three different procedures have been developed based on this database. The first two, alpha and lambda methods, are based on total stress concepts. The third, beta method, is based on effective stress concepts. 

P is the an empirical factor that is a function of soil type, stress level, and OCR Cu is the undrained shear strength found from friaxial compression tests... 

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