Analysis of predictor equations for determining the blast-induced vibration in rock blasting

The paper proposes a new empirical correlation designed to complement the‘‘site laws"currently used to evaluate the attenuation in the rock masses of vibrations induced by rock blasting.The formula contains a deformed exponential known as the K-exponential,which seems to well represent a large number of both natural and artificial phenomena ranging from astrophysics to quantum mechanics,with some extension in the field of economics and finance.Experimental validation of the formula was performed via the analysis of vibration data covering a number of case studies,which differed in terms of both operation and rock type.A total of 12 experimental cases were analysed and the proposed formulation exhibited a good performance in 11 of them.In particular,the proposed law,which was built using blast test data,produced very good approximations of the points representing the vibration measurements and would thus be useful in organising production blasts.However,the developed formula was found to work less well when a correlation obtained for a given site was applied to another presenting similar types of rocks and operations,and thus should not be employed in the absence of measurements from test data.

An innovative bio-engineering retaining structure for supporting unstable soil

The paper presents a new prefabricated bio-engineering structure for the support of unstable soil.This prefabricated structure is made of a steel frame which is completely filled with soil and a face made of tree trunks among which scions or autochthonous bushes are planted.Due to the difficulties in interpreting the complex interaction between soil and structure during the installation and lifetime,an in situ test was carried out in order to evaluate the state of stress in the steel frame and to understand the global behavior of the structure under service loads.On the basis of the obtained results,a procedure for checking the structure safety was proposed and discussed.An easy design method was developed during the research.Moreover,the use of this type of prefabricated structure shows several advantages,such as good performances in terms of stabilizing effects,and easy assembly and transport.

Mechanical properties of microcrystalline branching selenite gypsum samples and influence of constituting factors

The high sedimentological variability of gypsum rocks has the effect that a univocal characterization of this material is not easy to establish. This is particularly true from the geomechanical point of view: when the mechanical properties of gypsum rocks are requested, it is therefore necessary to undertake detailed characterization analyses. Common facies of gypsum was observed in the Upper Miocene evaporitic succession(Messinian Salinity Crisis) within the whole Mediterranean Basin. In this work, mechanical tests were conducted on a site-specific facies, represented by the microcrystalline branching selenite. The tested samples came from the Monferrato area(northwestern Italy). Uniaxial compressive strength(UCS)tests were performed in order to obtain reference mechanical parameters. More rapid and economic point load test(PLT) and ultrasonic pulse velocity(UPV) measurements were additionally performed to verify their applicability as complementary/alternative methods for site characterization. Rock-type specific PLT-UCS and UPV-UCS relationships were established. A wide dispersion of the mechanical parameters was observed due to the heterogeneities of the studied material. Consequently, compositional, textural and microstructural observations on selected samples were performed. Two main material classes were recognized based on average grain size and total gypsum content, underlining the significant influence of the grain sorting on the measured mechanical properties.