The role of plastic deformation in normal loading and unloading cycles

2001 ◽  
Vol 80 (3-4) ◽  
pp. 209-227 ◽  
Author(s):  
M. Onida ◽  
F. Galadini ◽  
F. Forcella

AbstractPaleoseismological techniques have been used to investigate gravitational deformations at the Mortirolo Pass (Valtellina region, central Alps), in order to improve the knowledge on the activation mechanisms and the evolution of deep-seated gravitational slope movements. The deformation has been responsible for mass sliding towards the Valtellina depression through the activation of several-hundred-metre-long shear planes. Minor shear planes dipping towards the mountain played the role of antithetic structures. Four trenches were excavated across scarps representing the surficial expression of shear planes affecting the bedrock and Late Pleistocene-Holocene deposits. The excavations enabled to investigate the stratigraphy of Quaternary deposits and the geometry and kinematics of the shear planes affecting them. Radiocarbon analyses on organic material contained in sediments and paleosols enabled to define a succession of displacement events which occurred during the Late Pleistocene-Holocene. Collected data indicate the persistence of the activity until recent times (last movement related to 1810-1540 cal. BP). A sudden movement has been detected along one of the main shear surfaces (dipping towards the valley) with a vertical displacement of several metres. In contrast, numerous displacements (with lower vertical offset) have been detected along the antithetic shear planes. Different hypotheses have been proposed in the past to define the origin of huge gravitational movements (glacial retreat, uplift of the Alpine chain, fault activity). However, the Late Pleistocene cycles of glacial loading and unloading on the mountain slopes seem to be the most probable factors causing deep-seated gravitational movements in the investigated region. A recent dramatic landslide in an area adjacent to the investigated one (Mt. Zandila-Valpola) testifies to the paroxistic evolution of the large scale gravitational deformations. The densely inhabited Valtellina region is affected by a large number of gravitational structures similar to those of the Mortirolo area. In consideration of the possible effects of the paroxistic activation of these structures, detailed studies on the chronology and kinematics of the deformations through the application of paleoseismological techniques should therefore be encouraged.


2020 ◽  
Vol 170 ◽  
pp. 110648 ◽  
Author(s):  
C.X. Dang ◽  
P. Zhang ◽  
J. Li ◽  
Z.H. Gao ◽  
B. Li ◽  
...  

Soft Matter ◽  
2017 ◽  
Vol 13 (27) ◽  
pp. 4746-4755 ◽  
Author(s):  
Mitchell L. Sesso ◽  
George V. Franks

This work demonstrates a method of measuring the fracture toughness of particulate materials comprised of colloidal sized particles over a wide range of saturation.


2013 ◽  
Vol 67 ◽  
pp. 126-132 ◽  
Author(s):  
G. Polt ◽  
F. Spieckermann ◽  
H. Wilhelm ◽  
M.B. Kerber ◽  
E. Schafler ◽  
...  

2005 ◽  
Vol 68 ◽  
pp. 144-146
Author(s):  
Colin J. Davis

In this autobiographical account of labor relations on the Montreal waterfront, Alexander C. Pathy gives an insider account of the volatile relationship between shippers and longshoremen. Pathy worked as a lawyer and then official of the influential Maritime Employers Association (MEA). The MEA was in the forefront in changing employment relations to better fit the introduction of technological changes brought on by containerization. As in most ports around the world, the introduction of containerization was riven with challenge and controversy. The Port of Montreal, and the lesser ports of Quebec City and Trois-Rivieres, shared this common experience. According to Pathy up to 1960 the respective ports had seen little strife. Indeed, it would seem that the relations between the two sides had been relatively amicable. This would change once ship owners and stevedores embarked on a rationalization scheme to make the loading and unloading of cargo that much more efficient and speedier. Beginning in 1960, negotiations became increasingly heated and hostile. Not least was the problem of language. In what could be best described as mutual ignorance the employers negotiated in English, while the union representatives, reflecting the membership, spoke in French. It was no wonder that misunderstandings could occur because of poor translation. But according to Pathy more than language, the principal point of conflict was perception. Each side brought to the table mutual suspicion and hostility. The problem Pathy contends was, “Each party did not see its glass half full but half empty.”(40) Therefore, negotiations over gang size, technological improvements, hiring methods, and union jurisdiction all became major issues of contention. Adding to the complexity of the situation was the role of Canadian government. Canadian industrial relations law gave the government a vital stake in the negotiations. Just as important, as both official and wildcat strikes broke out, the government scrambled to stabilize the situation as ships were diverted to US ports. The loss of trade and thereby revenue was seen as a critical impairment to the maritime economy.


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