Wyniki wyszukiwania - BazTech

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Surface Deformation due to Loading of a Layered Elastic Half-space : Constructing the Solution for a General Polygonal Load

Bevis M., Pan E., Zhou H., Han F., Zhu R.

Acta Geophysica

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2015

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Vol. 63, no. 4

957--977

EN

We describe an algorithm for rapidly computing the surface displacements induced by a general polygonal load on a layered, isotropic, elastic half-space. The arbitrary surface pressure field is discretized using a large number, n, of equally-sized circular loading elements. The problem is to compute the displacement at a large number, m, of points (or stations) distributed over the surface. The essence of our technique is to reorganize all but a computationally insignificant part of this calculation into an equivalent problem: compute the displacements due to a single circular loading element at a total of m n stations (where m n is the product m × n). We solve this “parallel” problem at high computational speed by utilizing the sparse evaluation and massive interpolation (SEMI) method. Because the product m n that arises in our parallel problem is normally very large, we take maximum possible advantage of the acceleration achieved by the SEMI algorithm.

2

Earth crust deformation in Poland: modelling and its implication for positioning with satellite based geodetic techniques

Rajner M.

Reports on Geodesy

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2012

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z. 1/92

37—46

EN

This paper gives the general overview of the effects which continuously deform our planet. The main aim is to give the picture of the temporal and spatial range of this phenomena and to indicate their importance in high precision positioning with space geodetic techniques. We present here the ranges of magnitude and pattern of earth tides, ocean tidal loading, atmospheric radiation tides loading, polar motion and its oceanic indirect effect, as well as the non-tidal ocean loading. We pay the special attention to loading effects due to atmosphere and continental water storage, which can cause significant changes in point position time series. Our study concentrate mainly on the territory of Poland. The Jozefosław site was chosen as a representative example for the whole country. We present also here the impact of selected phenomena for relative geodetic measurements.

3

Studies of crustal deformation due to hydrological loading on GPS height estimates

Rajner M., Liwosz T.

Geodesy and Cartography

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2011

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Vol. 60, no 2

135-144

EN

The paper deals with large-scale crustal deformation due to hydrological surface loads and its influence on seasonal variation of GPS estimated heights. The research was concentrated on the area of Poland. The deformation caused by continental water storage has been computed on the basis of Water GAP Hydrological Model data by applying convolution of water masses with appropriate Green's function. Obtained site displacements were compared with height changes estimated from GPS observations using the Precise Point Positioning (PPP) method. Long time series of the solutions for 4 stations were used for evaluation of surface loading phenomena. Good agreement both in amplitude and phase was found, however some discrepancies remain which are assigned to single point positioning technique deficiencies. Annual repeatability of water cycle and demanding procedure for computing site displacements for each site, allowed to develop a simple model for Poland which could be applied to remove (or highly reduce) seasonal hydrological signal from time series of GPS solutions.

PL

Celem niniejszej pracy jest analiza wpływu zmian wielkoskalowych stosunków wodnych na deformacje skorupy ziemskiej. Przedstawiona jest również możliwość monitorowania tego efektu przy pomocy geodezyjnych technik satelitarnych. Na podstawie zmiennego rozkładu mas hydrosfery lądowej (do tego celu wykorzystano model hydrologiczny WGHM) oraz wykorzystując informacje dotyczące właściwości skorupy ziemskiej (tzw. funkcje Greena) zostały obliczone modelowe zmiany wysokości wybranych punktów na terenie Polski. Wyniki te zostały porównane ze zmianami wysokości wyznaczonymi dla czterech stacji permanentnych GNSS, które dysponują długimi ciągami obserwacyjnymi, tj. Borowa Góra, Borowiec, Józefosław oraz Lamkówko. Do opracowania obserwacji GPS wykorzystana została metoda Precise Point Positioning (PPP), czyli obserwacje dla każdej stacji były opracowywane niezależnie. Pozwoliło to na odseparowanie sygnałów właściwych dla danej stacji pomiarowej i prawidłowa interpretacje geodynamiczna. Wyniki te dobrze zgadzają się co do amplitudy i fazy z modelowym efektem. Przyczyny widocznych rozbieżności również zostały przedyskutowane. Wyraźna, roczna powtarzalność deformacji wynikających ze zmiennego rozkładu mas wodnych, pozwoliła na skonstruowanie prostego dwuparametrowego modelu dla terenu Polski, który pozwala znacznie zredukować wpływ tego efektu bez konieczności złożonych obliczeń.

4

The influence of general surface loading on penetration of a circular punch into an elastic stratum

Rogowski B., Zaręba D.

Engineering Transactions

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1998

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Vol. 46, iss. 2

205-215

EN

The first of the authors (B.R.) derived an expression for the pressure distribution inside a circular region with vanishing shear tractions and normal displacements, due to the application of the forces distributed along the circumference on an elastic transversely isotropic half-space. This results is used to derive the relationships between the forces, moments and indentations for a punch acting on an elastic half-space. The results are given in terms of elementary functionss, The influence of an annular punch encircling a central punch is considered. The stress intensity factor of Mode I related to non-symmetric stress distribution in the vicinity of ann external crack under general surface loading, symmetric with respect to the crack plane, is also presented in terms of elementary functions.