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2 Archives of Hydro-Engineering and Environmental Mechanics

2 2004

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The Perfect Ménard Pressuremeter Curve

Tarnawski M.

Archives of Hydro-Engineering and Environmental Mechanics

2004

Vol. 51, nr 4

387-402

As it is commonly known, to obtain a good quality Ménard Pressuremeter Test a perfectly drilled borehole (pocket) is required. It should be of proper size, only slightly greater than the diameter of the pressuremeter probe, and its walls should remain undisturbed. Unsatisfactory shapes of pressuremeter curves result usually from a poor quality drilling. Typical examples of such curves are given in all handbooks dealing with pressuremeters. They correspond to situations when the tested cavity is too large, too mall or its walls are collapsed. There is, however, plenty of room between the pressure and volume axes. An infinite number of various curves can run through this field and only one of them is really the proper one. An interpreter should be able to evaluate the quality of any curve obtained, estimate the source, the direction and the approximate scale of error and finally to draw conclusions on how to improve the drilling technique to avoid or minimize any future errors. To be able to do that, one needs to understand how the perfect curve should look. The present paper is a study on shapes of pressuremeter curves based on the author's 25years' experience.

Implicit versus explicit finite volume schemes for extreme, free surface water flow modelling

Szydłowski M.

Archives of Hydro-Engineering and Environmental Mechanics

2004

Vol. 51, nr 3

287-303

One explicit and three implicit finite volume method schemes of the Roe type are presented in the paper. The properties and applicability of these methods for modelling unsteady, rapidly varied, open channel flow are investigated. The schemes are used for numerical simulation of one-dimensional extreme flow described by de Saint-Venant equations. The computational results are compared with each other and an analytical (exact) solution to an idealized dam-break problem. The classical versions of general scheme implicit in time - fully implicit and trapezoidal scheme - are not restricted by a stability condition, like an explicit one, however they add some numerical diffusion and dispersion errors to the solution. The modification of parameter , originally proposed for a box scheme of finite difference method, has improved computational properties of the general one-step implicit scheme. This version of finite volume scheme of the Roe type implicit in time can be recommended for modelling and simulation of transient flows in storm sewers and open channel networks.