One of the standards most commonly used in Croatia is the standard BS 1377:1990, Part 8, paragraph 7. This parameter typically correlates well with rock hardness and density, which in turn tend to correlate with changes in lithology, degree of fracturing, water content, and weathering. Seismic methods can provide valuable information of the subsurface, such as the seismic velocity structure of the geology (e.g. In most cases a 12-channel system was used. The seismic refraction method involves analysis of the travel times of the first energy to arrive at the geophones. If you continue browsing the site, you agree to the use of cookies on this website. select among the possible technical solutions the most advantageous (in term of stability, strength and costs). Earth exploration - Earth exploration - Seismic refraction methods: Seismic methods are based on measurements of the time interval between initiation of a seismic (elastic) wave and its arrival at detectors. The Seismic Refraction method involves the measurement of travel times of seismic compressional waves (P-waves) that are generated at the surface, propagate through the subsurface and return to the surface after being refracted at the interface between layers of contrasting seismic velocity. Therefore is of major interest to have an improved knowledge upon the hazardous geological features, to evaluate them and to, Possibilities of protection of a construction excavation during the construction of deep foundations for a bridge in riverbed are tested in this work. ISO/TS 17892-9:2004; ISSMGE ETC5-F1.97; Simons, N., Menzies, B.(2000)). This technique is termed seismic refraction. The new tunnels routes were also prospected by means of seismic refraction, with the aim to obtain high resolution data of the geological formations and hence to avoid some of the most common troublesome elements for such constructions. These differences include advantages, disadvantages and conceptual challenges in utilizing the results. Conference: International Balkans Conference on Challenges of Civil Engineering, BCCCE. An Introduction to Seismic Refraction Theory and Application 1. Seismic refraction interpreting methods like intercept-time method, generalized reciprocal method, delay time method or refraction tomography, are used to determine the near-surface model and the travel time correction values. Consolidation grouting has been carried out under reactor buildings upto 15m depth and surrounding area upto 10m depth. Seismic refraction study, single well test and physical core analysis of anthropogenic degraded Peat at the Badas Peat Dome, Brunei Darussalam, Subsurface Profile Mapping using 3-D Compressive Wave Imaging, Seismic Refraction Analysis of Landslides, SEISMIC REFRACTION INTERPRETATION WITH VELOCITY GRADIENT AND DEPTH OF INVESTIGATION, Prediction of the nonlinear load - settlement relationship for shallow foundations on granular soils. The seismic reflection method These tools are also able to identify multiple lithological structures based on their geophysical and geotechnical properties, Application of seismic refraction studies in the design of viaducts; First BiH Congress on Roads; Proceedings. © 2008-2021 ResearchGate GmbH. In all three examples, seismic refraction surveys and analyses of the data provided information integral to understanding and characterizing the landslides. 1. Two-shot reverse profiling seismic refraction was conducted in the targeted areas. The conduct of triaxial tests and use of test results undoubtedly facilitate rationalization during construction of geotechnical structures and civil engineering structures in general. It is important to treat the seismic information as an independent source of data for an overall geological model that is developed for the site. G.Mitrovic, Application of seismic refraction studies in the design of viaducts; First The seismic refraction method utilizes the refraction of seismic waves on geologic layers and rock/soil units in order to characterize the subsurface geologic conditions and geologic structure. This method was used as reconnaissance to locate the bedrock valleys. The picked phase should be defined with great care. Osim ovog standarda, primjenjivi su još neki standardi i preporuke(ASTM D 4767 – 04; ISO/TS 17892-9:2004; ISSMGE ETC5-F1.97;Simons, N., Menzies, B.(2000)). 2/GPH221L9 KSU 2012-2013 I. Method Use of this approach has been critical in achieving substantial reductions is cost overruns attributable to geotechnical conditions. Seismic refraction is one of the methods of geophysics used to investigate subsurface ground conditions for trenchless operations. See our User Agreement and Privacy Policy. seismic reflection). Refraction tomography, another method of interpreting seismic refraction data, is capable of modeling these complex velocity structures. The receivers are arranged to one side of a shot, which is 15 m from the first geophone. The geological mapping and borehole drilling were carried out which revealed that the founding stratum is basically a weathered granite hypersthenes with varying degree of weathering and occasional presence of calcareous material. A combination of these methods (seismic refraction, single well test and coring) are suitable for identifying different levels of peat degradation. This paper presents two examples of preparation of seismic sections as a basis for geotechnical design of foundations. Over the years, this area has seen a noticeable loss of peatland due to fires and infrastructure development. The interpretation is based on Heiland (1946). In principle this means that the refraction arrival of interest is approximately horizontal in the travel-time diagram. These first arrivals are from either the direct wave (at geophones close to the source), or critically refracted waves (at geophones further from the source). calculations and calculations using the computer program Plaxis are performed. The Badas peat dome located in the Belait district is one of the biggest peat domes in Brunei. All rights reserved. In particular, a sand horizon underlying the peat deposits was identified which has the potential to be a significant hydrogeological flow unit. Satellite images were used to confirm the extent of past peat fires in the area. The seismic wave may be generated by an explosion, a dropped weight, a mechanical vibrator, a bubble of high-pressure air injected into water, or other sources. Geotechnical site investigation related to subsurface profile mapping was commonly performed to provide valuable data for design and construction stage based on conventional drilling techniques. SAŽETAK Provođenje troosnih pokusa i upotreba rezultata ispitivanja nedvojbeno znatno doprinose racionalizaciji tijekom izgradnje geotehničkih i općenito građevinskih konstrukcija. In particular high standards have been developed for seismic refraction information and its integration into overall geotechnical information in relation to detailed design, documentation for, This paper presents improvement of rock-strata below the foundation of two reactor buildings for a 2 × 1000 MW Nuclear power plant by compaction grouting. Join ResearchGate to discover and stay up-to-date with the latest research from leading experts in, Access scientific knowledge from anywhere. This method of seismic refraction is common and provides a depth to bedrock under each shot location. Clipping is a handy way to collect important slides you want to go back to later. (2) is the most common method (also called refraction statics), especially when using surface seismic sources. After data processing, an image of the crust is obtained (Fig. They are all artistically enhanced with visually stunning color, shadow and lighting effects. Standards currently in use are compared, and their applicability in real-life design situations is analyzed. Single well tests conducted in this study showed that disturbed peat had lower hydraulic conductivities with an average of 1.73 × 10⁻⁵ m/s compared to undisturbed peat with an average of 6.66 × 10⁻⁵ m/s. As the angle of incidence is increased, the geometry results in a head wave travelling horizontally in layer 2. Abrupt increases in the gradient velocity with depth inconsistent with confining pressure may be a reasonable indicator of cemented or cohesive materials rather than cohesionless materials. The author is presently performing interpretations using a combination of both traditional and velocity gradient interpretation to utilize the advantages of both concepts. The author has observed that interpretations in geologic environments containing velocity reversals, where an underlying horizon seismic velocity is lower than in the overlying horizon, the velocity gradient method tends to interpret shallow depths of investigation consistent with bottom depths of the higher velocity horizons. Seismic Refraction Figure 2. Schematic of the seismic reflection method. Seismic refraction method was used to delineated two distinct layers with the first layer having a weak and incompetent parameter values. From past experience, drilling techniques particularly using borehole method suffer from limitations related to expensive, time consuming and limited data coverage. Seismic refraction maps contrasts in seismic velocity – the speed at which seismic energy travels through soil and rock. Hence, this study performs subsurface profile mapping using 3-D compressive wave imaging in order to minimize those conventional method constraints. Times elapsed from sending to receiving seismic waves depend on depths of studied structures and propagation velocities of seismic waves along paths of their propagation from the source to the refractor (or reflector) to the receiver. Using these methods, this study has identified multiple peat, sand and clay layers demonstrating the stratigraphic heterogeneity that can be present in tropical peatlands. In another example, velocity models of a landslide generated using GRM and tomography indicate low-velocity slide material over a steeply dipping, concave, high velocity unit interpreted to be bedrock characteristic of a rotational failure. The T-X method averages out depth variations, although the plus-minus method will show them from the same data It is incapable of fine detail, especially if the bedrock is irregular or lacks internal elastic contrasts. A survey of a different landslide identified a localized high velocity zone in the near surface indicative of a bedrock block within the slide mass. C3.1 Seismic refraction – single horizontal interface The P-wave is refracted at the interface between the two layers. Seismic waves generated by closely spaced chemical bore-hole explosions are recorded by closely spaced seismic recorders on a linear profile. Jedan od najčešće korištenih standarda u Hrvatskoj je standard BS 1377:1990, Dio 8, točka 7. It can be used to derive important details about the geometry of structures and their physical properties. The GRM assumes a layered model and is effective when the velocity structure is relatively simple and refractors are gently dipping. Seismic methods are applied primarily in order to determine quasi-homogeneous zones according to parameters of fragmentation, physical and chemical weathering and deformability of rock masses and cohesionless soil. Standard investigation techniques based on drilled boreholes (up to 80m depth), and in situ & laboratory determination of geotechnical parameters of interest (permeability, bulk weight, cohesion, friction angle, Youg's modulus, Poisson coefficient, waves velocities, unconfined compression strength) were applied to obtain the necessary datasets to characterize the terrain and to get estimate data about water infiltration at the tunnel level. The seismic refraction method, due to its versatility, is one of the most commonly used geophysical methods in engineering, mining, groundwater exploration and environmental site investigations. For the chosen geotechnical problem, two different variants of the construction excavation protection are analyzed. Then, 3-D compressive wave distribution of subsurface studied was obtained using analysis of SURFER software. In addition to this standard, some other standards and recommendations are also applied (ASTM D 4767 – 04; The Roads and Traffic Authority of NSW (RTA) (Australia) has developed a high standard of practice in collecting, interpreting and documenting geotechnical information for road construction contracts. Seismic Refraction Method Overview (2) Prepared by Dr. Amin Khalil 2. refraction survey, three major and distinct layers of rock are identified below the founding depth of the reactor buildings: weathered rock of about 4.5m thickness, semi-weathered rock of average thickness 10m and hard rock occurring at a depth of about 15m below founding level. Dr. Amin Khalil. Looks like you’ve clipped this slide to already. What is Seismic Refraction? Both examples are presentations of an optimum program of exploratory boring supplemented by results of deep seismic refraction studies. Applied seismic methods comprise sending impulses underground and registering the resulting refracted arrivals from subsurface interfaces on a number of receivers positioned on or near the surface. In order to determine the degradation impact on peat through lowering of groundwater levels using these methods we produced a subsurface reconstruction at two locations with different levels of peat degradation. Illustration of common depth point (often called common mid point). Furthermore, rippability criteria developed over the last 30 or more years predates velocity gradient interpretation methods; velocities obtained by these methods may not match with traditional velocity interpretations. A profound advantage is an explicit interpretation of depth of investigation defined by the grids utilized in the interpretation. 2. If you continue browsing the site, you agree to the use of cookies on this website. You can change your ad preferences anytime. Used in the fields of engineering geology, geotechnical engineering and exploration geophysics, seismic refraction traverses (seismic lines) are performed using a seismograph(s) and/or geophone(s), in an array and an energy source. In this study we address the assessment of an area were two parallel double track tunnels were planned to be constructed. Field measurement and data analysis of compressive wave (p-wave, vp) was performed using seismic refraction survey (ABEM Terraloc MK 8, 7 kg of sledgehammer and 24 units of vertical geophone) and OPTIM (SeisOpt@Picker & SeisOpt@2D) software respectively. Seismic Reflection Method . A note is also made of test specification steps, given the specifics of materials falling within the hard soil to soft rock range. Another possibility of interpreting seismic refraction data is the refraction-tomography, which is pre-sented in chapter IV. contract tendering, road construction and its possible use in evaluating contract claims. Before stacking reflection seismic data, a normal move-out correction is applied. WesternGeco presentation - Seismic Data Processing, Land Seismic Sources - Explosives Vs. Vibroseis, No public clipboards found for this slide. 1921: ‘Seismos’ company founded to use seismic refraction to map salt domes, often associated with hydrocarbon traps. Extensive confirmative geological, geophysical and geotechnical investigations were carried out at founding level after exposing the founding rock strata. MODELING OF A PROTECTIVE STRUCTURE FOR THE CONSTRUCTION OF DEEP FOUNDATIONS IN RIVERBED, Comparison of standards for conducting CIU tests and analysis of test results, Seismic refraction in relation to geotechnical information for (road) construction contracts, IMPROVEMENT OF ROCK STRATA FOR FOUNDATION OF REACTOR BUILDINGS. Layered horizons or zones where each horizon has a discrete a seismic velocity a. Concept of layered horizons or zones where each horizon has a discrete a seismic reflection record can used! One of the travel times of the biggest peat domes in Brunei jedan od najčešće korištenih u... Integral to understanding and characterizing the landslides refraction is a useful geophysical tool seismic refraction method diagram. 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