New approach in the application of seismic methods for assessing surface excavatability of sedimentary rocks
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ORIGINAL PAPER
New approach in the application of seismic methods for assessing surface excavatability of sedimentary rocks Jasmin Jug 1
&
Davor Stanko 1
&
Kristijan Grabar 2 & Petar Hrženjak 3
Received: 19 August 2019 / Accepted: 8 April 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract In the present study, a new approach on the application of seismic methods for assessing the excavatability of sedimentary rocks for surface excavations is proposed. The excavatability classification system has been developed based on seismic S-waves velocities determined by the multichannel analysis of surface waves. Prior to practical excavations carried out with different excavation methods (blasting, hydraulic breaking, ripping and digging), extensive field and laboratory studies were performed on eight sedimentary rock sites displaying a wide range of weathering and strength conditions in the area of Croatian karst (Dalmatia, Istria, Gorski Kotar). The investigation involved parameters of intact rock, such as compressive strength and point load strength, and parameters of rock mass such as seismic P-waves and S-waves velocities, geological strength index, discontinuity spacing and rock quality designation from borehole core. A new classification was proposed by comparing the measured VS and applied excavation methods on the studied sites. Estimates of several existing classifications were used for comparison and verification. It was found that the estimates of the proposed model are comparable with the estimates of previous research. The proposed method is not applicable to igneous and metamorphic rocks, or for subsurface excavatability assessments. Keywords Excavatability assessment . Sedimentary rocks . Seismic S-waves . MASW . Surface excavation method
Introduction The selection of the most appropriate excavation method is one of the most important tasks during the design and construction of various engineering objects in rock masses (surface mines, highways and rail routes, foundations). These decisions are particularly important as they affect and determine the cost and time required for the entire project (Liang et al. 2017a). The term excavatability is used as a broad term that refers to the ease of excavation of rock and rock masses and includes the following methods: (a) digging when easy/very easy excavation conditions exist, (b) ripping for moderate to difficult
* Jasmin Jug [email protected]; [email protected] 1
Faculty of Geotechnical Engineering, University of Zagreb, Hallerova aleja 7, Varaždin, Croatia
2
SPP d.o.o, Trstenjakova 3, Varaždin, Croatia
3
Faculty of Mining, Geology and Petroleum Engineering, University of Zagreb, Pierottijeva 6, Zagreb, Croatia
excavation conditions and (c) blasting for very difficult excavation conditions (Tsiambaos and Saroglou, 2010). If the main purpose of the excavation work is to break rock into smaller fragments by using a hydraulic hammer, the fourth method can be called (d) breaking. Cutting is also one of the known mechanica
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