CPT tests

However, the most stringent CPT test comes from a mass comparison of the neutral kaon and antikaon, where the tremendous accuracy of 10-18 has been reached, albeit in a theoretically dependent manner. Not only does the comparison only restrict CPT violation to 1 part in 103 of CP violation, the origin of which itself is not fully understood, but it has been argued [9] that the analysis leading to this limit assumes the validity of the standard model, which in itself does not contain a mechanism for CPT violation. 

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... 

Now a days the CPT test is also widely being used for the evaluation of site classification. The soil classification schemes based on CPT values are given in Table 3. 

This second lecture also introduces students to various methods of site investigation used in the project. Particular emphasis is given to describing CPT testing and how the results of such tests are used by engineers to interpret the subsoil conditions at a site and to obtain parameters for modeling the soil. A CPT probe is handed around the class for students to gain a better appreciation of the methods. 

Schmertmann (1978) recommended a method to estimate the pile capacity by using the CPT test ... 

Although often neglected, information on the relative density in the borrow area is required for an accurate estimate of the dredging production. The in situ relative density can be determined by boreholes (with SPT testing) or CPT-testing. 

The relative density of the fill can be tested by several methods after realisation of the fill. The most common method is the use of the Cone Penetration Test (CPT). The Standard Penetration Test (SPT) is an alternative method although less frequently used. The CPT test has the advantage to provide a continuous profile. Some correlations between CPT or SPT results and relative density can be found in appendix C, Correlations and correction methods. 

A more practical approach is to use CPT testing. A criterion related to the cone resistance and friction ratio can be used to define a layer of fines. When necessary this criterion can be checked with boreholes. 

Special attention should be paid to the saturation of the cone when testing fill placed above the water table. Since saturation of the cone can be time consuming, often only standard CPT testing is performed when significant fill layers are present above the water table. 

Boreholes can be drilled to sample the fill material throughout the entire layer thickness of the fill. Alternatively CPT testing can be used after calibration with the borehole results. The advantage of CPT testing is the speed of execution and the continuous recording of the Cone resistanee, the friction ratio and the pore pressure. 

The in situ density of deeper layers is generally tested by means of a CPT test. Correlations between CPT testing and relative density are used (see appendix C). It is strongly advised to specify which correlations and corrections are to be used. 

In case the CPT is used to evaluate the compaction results of vibroflota-tion compaction, the CPT test locations relative to the vibroflotation grid should be specified. (See Section 7.5.3, Figure 7.10). 

In view of the difficulties related to the correlation of the Relative Density to the Cone resistance values (see Section S.4.3.5), rather than using literature correlations, a practical way forward could be to setup a site specific correlation. A tempting approach could be to correlate CPT test results with density measurements on undisturbed samples originated from adjacent boreholes. This is however not possible since undisturbed samples cannot be retrieved from boreholes in non-cohesive soils. Therefore, when setting up a site specific Relative Density - correlation, calibration chamber tests are required. New promising developments with nuclear density probes allow for direct measurement of densities (see Appendix B.2.3.2). 

For each acceptance area, after completion of the Cone Penetration Testing, the Contractor shall submit the results of the CPT testing to the Employer... 

In situ density Nuclear method All soil types In situ density In combination with CPT test... 

Since no friction is measured, it is difficult to distinguish clayey soils from sandy soils. It is therefore advised to perform CPT testing as much as possible ... 

In case there is no time for a calibration chamber test, and there are serious doubts about the correlation to be adopted, it is advised not to use CPT-testing as a means to determine the relative density of the sand. In such cases, other testing meth-... 

Almeida, M.S.S., Jamiolkowksi, M. and Peterson, R.W. Preliminary results of CPT tests in calceare-ous Quiou Sand, Proceedings of the first international symposiiun on calibration chamber testing,... 

Seed and De Alba. Use of SPT and CPT test for evaluating the liquefaction resistance of soils, Proc. Insitu, ASCE, 1986. 

Young s Modulus at very small deformations Young s Modulus at 50 /o of the failure stress Friction Ratio CPT test Shear Modulus... 

The small-strain values of the soil shear modulus or the shear wave velocity may be determined by a variety of methods, the choice depending on the variability of the soil conditions, available knowledge on the material behavior, and the importance of the stmcture. These methods include (i) empirical relationships in terms of the SPT blow count or of the tip resistance of the CPT tests, (ii) geophysical field methods based on wave propagation, and (iii) dynamic laboratory tests. An overview of the testing procedures and available design equations is summarized by Kramer (1996). 

---