Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018最新文献

{"title":"LABORATORY EFFORTS TO DEVELOP A BOREHOLE NONDESTRUCTIVE TESTING SYSTEM TO INSPECT IN SITU FOUNDATION ELEMENTS","authors":"Alireza Kordjazi, J. Coe","doi":"10.4133/SAGEEP.31-021","DOIUrl":"https://doi.org/10.4133/SAGEEP.31-021","url":null,"abstract":"A nondestructive testing system was developed to evaluate foundations embedded in the subsurface. The system functions by generating elastic stress waves as it is lowered in a borehole alongside the foundation. Reflections from the foundation element are recorded and plotted to develop a high resolution image. The system is intended for inspection purposes of in-service foundation elements, particularly deep foundations for critical infrastructure. In this study, a large soil model was developed with a reduced-scale deep foundation element embedded within the model subsurface so that system performance could be evaluated. The foundation element features several anomalies, which replicate issues with foundation integrity in the field. The system was capable of differentiating between competent and anomalous sections of the foundation element. A summary of hardware components, system operation, and soil model construction/geometry is presented as well as the results from laboratory testing.","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126567972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"EFFECT OF INPUT-SOURCE FREQUENCY CONTENT ON RESULTS FROM SEISMIC TECHNIQUES FOR THE VS PROFILE DEFINITION IN SPATIALLY VARIABLE SOILS","authors":"Díaz-Durán, G. Cascante, M. Pandey","doi":"10.4133/SAGEEP.31-028","DOIUrl":"https://doi.org/10.4133/SAGEEP.31-028","url":null,"abstract":"All around the world, foundation and construction codes consider the shear wave velocity (VS) profile as a good indicator of soil stiffness. The definition of a VS profile is a very common practice for site classification and soil characterization in geotechnical engineering. In order to obtain the VS profile there are typically two approaches: direct exploration (e.g. Seismic Cone Penetration Test ‘SCPT’) and indirect exploration (e.g. seismic refraction ‘SR’ and multichannel analysis of surface waves ‘MASW’ techniques). Both, direct and indirect techniques require the use of an energy source to generate the waves necessary to characterize the VS soil profile; for near surface (depth less than 30m) usually an impact force is used as input source. The shear wave velocity (Vs) is equal to the product of wave length () and wave frequency (f). On one side, wave length represents the limitation in terms of vertical resolution for indirect techniques; the shorter the wave length, the better the vertical resolution (thinner layers can be detected). On the other side, frequency content for the input source is not very well studied and its effect on vertical resolution for the Vs profile is not very well understood. As the Vs depends only on the soils variability, there is no way to modify it in the tests; so, what is modifiable in during the test is the frequency content in the input source and as a collateral effect, the wave length. Numerical Simulation By doing numerical simulations it is possible to analyze the effect of different approaches when interpreting the results obtained from seismic tests for soil characterization. In order to fully understand the results obtained in numerical models it is necessary to calibrate the model with theoretical results. One of the main assumptions when defining the VS profile for a specific site is the ‘layered-soil’ model. For each layer in the model it is assumed the soil properties are homogeneous. The layers’ definition is the result of an expert interpretation process which follows the Soil Behavior Type ‘SBT’ classification presented by Robertson (2009). Under this assumption the VS profile is obtained by using the ray-path theory for wave propagation and calculating a unique value for each layer corresponding with any specific SBT value. On the other hand, a different and innovative approach is possible, which considers the effect of spatial variability of soil properties when defining the VS profile. Under this approach the VS profile is defined considering the randomness in the soil’s shear-stiffness, so the ray-path theory for wave propagation must be carefully used in these models. Conclusions In this research the effect of frequency in the definition of VS profile was studied by using numerical models to simulate the seismic refraction ‘SR’ test and the ‘SCPT’ test. The numerical models included homogeneous deterministic and spatially variable shear stiffness (the latter using random fields). In ord","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129280975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ADVANCES IN SLIMLINE BOREHOLE GEOPHYSICAL LOGGING","authors":"J. Lococo","doi":"10.4133/sageep.31-005","DOIUrl":"https://doi.org/10.4133/sageep.31-005","url":null,"abstract":"The last 10 years in slimline borehole geophysics has seen numerous advancements. Borehole imagery logging has reached resolutions that allow investigators to visualize true-color borehole wall attributes, grain size features, rock fabric, and structural integrity. These slimline tools allow us to perform high resolution fracture characterization, casing thickness evaluation, along with many other applications. Acoustic televiewer amplitude logs are semi-quantitative and proportional to rock strength. Advances in data acquisition systems allow increased logging speeds, even at very high circumferential and vertical sampling intervals. Nuclear Magnetic Resonance (NMR) logging has evolved with much smaller diameter tools, running on standard commonly available geophysical wirelines, thus allowing entry into the mining and ground water communities. These tools operate in a borehole, like an inside-out MRI scanner, to provide direct sensitivity to hydrogen (groundwater and hydrocarbons). The tool projects a magnetic field several inches beyond the borehole axis, creating a cylindrical-shaped “sensitive region” from which the NMR signal is captured. This thin sensitive region is ideally located within the undamaged region of the formation, where the rocks and sediments are not disturbed by drilling. Direct detection and quantification of groundwater (including capillary and clay-bound water) is possible, along with detection and quantification of hydrocarbons and fluid diffusion, precise determination of porosity and water content, estimation of permeability, mobile/bound water fraction, pore-size distributions, and sensitivity to geometric and geochemical pore-scale properties. Advances in slimline borehole gravity tools over the past several years has found importance in mining applications, including bulk density determination, rock properties, and verification of surface and airborne gravity anomalies. Borehole gravity measurements have been used for detecting the presence of oil and gas, and reservoir mapping, delineating salt domes, in addition to typical applications to determine density with greater investigative area than traditional radioactive source tools. Advances in borehole Spectral Induced Polarization (SIP) are revealing its unique sensitivity to interfacial properties of porous materials. SIP is sensitive to fundamental pore geometric properties controlling fluid flow and recent case histories indicate the measurement can be a good estimation of permeability. Numerous authors have described links between SIP parameters and permeability. SIP methods are also very sensitive to changes in the interfacial properties that result from biogeochemical processes occurring in porous media due to natural and enhanced mechanisms. Many papers that link SIP properties to biogeochemical alterations of mineral surface area and/or mineral surface chemistry have been published in recent years. It is now considered a unique geophysical method regarding","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121602212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"APPLICATION OF 2D AMBIENT NOISE TOMOGRAPHY TO LEVEE SAFETY ASSESSMENT IN NEW ORLEANS","authors":"Koichi. A. Hayashi, J. Lorenzo, A. Gostic","doi":"10.1190/TLE37100740.1","DOIUrl":"https://doi.org/10.1190/TLE37100740.1","url":null,"abstract":"To develop noninvasive methods for levee inspection, we carry out shallow, active, and passive seismic investigations at three sites along levees in the New Orleans, Louisiana, USA, area: Industrial Canal, London Avenue Canal, and 17th Street Canal. These sites sustained damage from Hurricane Katrina in 2005 and have since been rebuilt. Recorded ambient noise data are processed using the common-midpoint spatial autocorrelation method. Dispersion curves obtained with active surface-wave methods and passive wave methods, which use both L-shaped and linear sensor arrays, show internally consistent similarities. Minimum frequencies range from 0.6 to 2 Hz and maximum frequencies range from 10 to 30 Hz. Nonlinear inversion of 2D S-wave velocity models generates velocity-depth cross sections that extend approximately 400–1000 m along levees and provide information to depths of 40–60 m. Resultant S-wave velocity (VS) profiles are generally consistent with existing drilling logs and the results of laboratory tests. Beneath the London Avenue Canal wall, VS values (130–170 m/s) likely correspond to saturated, unconsolidated sands, and a low-velocity (50–100 m/s) zone at depth to 15 m beneath the 17th Street Canal matches low-rigidity clays observed in geotechnical logs. Comparison to active surface-wave methods at the Industrial Canal site display similar results but highlight that while active methods have better resolution in the upper few meters, passive methods may be acquired more quickly.","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132941676","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"RESEARCH ON RELATIONSHIP BETWEEN ELECTRICAL RESISTANCE TOMOGRAPHY AND THE MULTIPLE-SCALE SIZE AND DEPTH OF ROCK FRACTURE","authors":"F. Jing, Li Xiaozhao, A. Tarantino, H. Zhen, B. C. Lopes","doi":"10.4133/SAGEEP.31-033","DOIUrl":"https://doi.org/10.4133/SAGEEP.31-033","url":null,"abstract":"Multiple sets of cracks exist in the fault fracture zone, damage zone and even intact rock mass, resulting in poor conductivity and high permeability of the hard rock fissure seepage channels. There are likely to become potential groundwater migration channels in the future, so that the underground engineering is facing huge challenges. To more accurately grasp the characteristics of the permeability of rock mass and fracture, it is extremely important to get hold of the phenomena of internal structure model, genetic mechanism and dynamics principle in the multiple scales size and depth of rock fracture. In assurance of an accurate analysis result in the multiple scales of rock mass fracture, mastering the principles and patterns of the solute and flow medium migration rule in pore and fracture can provide scientific basis for underground construction engineering.","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126398268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Application of Underwater MASW and Acoustic Methods in the Assessment of Sub-seabed Conditions Prior to Construction of the Manifa Causeway, Saudi Arabia","authors":"K. Sayers, T. Fechner, C. Park, A. Verweerd","doi":"10.1190/ICEG2017-053","DOIUrl":"https://doi.org/10.1190/ICEG2017-053","url":null,"abstract":"The offshore Gulf Region is known to have caprock layer within the first 0-5m of ground below the seabed. It varies in thickness from a few centimetres to two or three metres in thickness. Caprock is predominantly a Gulf regional phenomenon forming in shallow coastal areas where there are small tidal movements and water circulation. It is typically a cemented Limestone anhydrite with a matrix of small shells and calcarenite.","PeriodicalId":156801,"journal":{"name":"Symposium on the Application of Geophysics to Engineering and Environmental Problems 2018","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125692527","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}