Testing the shear strength of soft rock at different stages of laboratory simulated weathering

Abstract

Testing the shear strength of soft rock at different stages of laboratory simulated weatheringDetermination of the change in strength based on simulation of weathering process in laboratory conditions is described in the paper, using marl samples taken from flysch formations in the region of Dalmatia. The testing has revealed that the proposed weathering simulation in laboratory can be conducted within acceptable time frames. Because of the observed change of shear strength parameters as related to values corresponding to the strength of material described as soil, it is sometimes necessary to use soil testing devices so as to take into account the load range applied in individual types of testing devices. Mjerenje posmične čvrstoće meke stijene u uvjetima laboratorijski simulirane rastrošbe U radu je opisano određivanje promjene čvrstoće temeljeno na simuliranju procesa rastrošbe u laboratorijskim uvjetima, koristeći uzorke lapora iz flišne formacije s područja Dalmacije. Na temelju provedenih ispitivanja zaključeno je da je predloženi postupak simuliranja rastrošbe u laboratoriju provediv unutar prihvatljivih vremenskih okvira. Zbog uočene promjene parametara posmične čvrstoće na vrijednosti koje odgovaraju čvrstoći materijala koji se opisuje kao tlo, ponekad je potrebno, zbog raspona veličine opterećenja koje se nanosi u pojedinom tipu uređaja, koristiti i uređaje za tlo. Messungen der Scherfestigkeit weichen Gesteins unter im Labor simulierten VerwitterungsbedingungenIn dieser Arbeit wird die Ermittlung von Änderungen der Scherfestigkeit weichen Gesteins aufgrund simulierter Verwitterungsprozesse unter Laborbedingungen an Mergelproben aus den Flysch-Formationen der Region Dalmatien beschrieben. Aufgrund der Untersuchungen geht hervor, dass das vorgeschlagene Verfahren zur Simulation der Verwitterung im Labor in vertretbarem Zeitrahmen durchgeführt werden kann. Bedingt durch den Einfluss von Änderungen der Scherfestigkeite auf die Festigkeit des Materials, das als Boden beschrieben wird, ist es manchmal notwendig bei großen Unterschieden der aufgebrachten Lasten, je nach Gerätetyp, auch Geräte für Bodenproben zu verwenden.

Application of geological strength index for characterization of weathering-induced failures

“…As shown in Table 6, samples from location at km 22+850 (designated J-1) are the least susceptible to disintegration, whereas samples from location at km 30+200 (designated J-3) exhibit the highest level of susceptibility to disintegration. Grain size curves for samples J-1(7), J-2(12), J-3(2), and J-3 (5) are shown in Figure 10.a to 10.d. It can be seen that the highest rate of disintegration is achieved during the first five month of exposure, whereas disintegration between 9 and 12 months of exposure is insignificant.…”

“…Miščević and Vlastelica [4] emphasize that if cut slopes in flysch rock mass stay unprotected, the failures could develop within months after excavation. The influence of laboratory simulated weathering on the shear strength of marl was also studied [5]. Lithological factors such as the degree of cementation, existence of microcracks, grain size, heterogeneity, and mineralogical composition (type of clay minerals), have an influence on disintegration.…”

Structure and Mechanical Properties of the Dueñas Clay Formation (Tertiary Duero Basin, Spain): An Overconsolidated Clay of Lacustrine Origin

“…Finally, density and strength using the point load test were examined on the rock samples [28]. The point load test was selected as an index method, which is useful when the natural conditions of the samples impede the preparation of cylindrical samples [31,32].…”

Preliminary Characterisation of an Italian Soft Rock with a Block-in-Matrix Fabric

“…Field estimates of uniaxial compressive strength of intact rocks (After [30], modified from [42]). Moreover, since soft rocks constitute transition materials between (hard) rocks and (stiff) soils, they are often too soft to be tested in rock mechanics apparatus and too hard for soil mechanics equipment [13,28,43]. Furthermore, they present numerous undesirable characteristics, such as low strength, disaggregation, presence of rock inclusions, capillarity suction, crumbling, high plasticity, slaking, and fast weathering [8,13,23,25,27,28,31,[44][45][46].…”