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1

Application of Clustering Method in Different Geophysical Parameters for Researching Subsurface Environment

Le Cuong Van Anh, Nguyen Ngan Nhat Kim, Nguyen Thuan Van

Inżynieria Mineralna

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2022

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no. 2

39--47

EN

Safety of construction needs knowledge of physical parameters as stiffness or porosity of the subsurface environment. Combination of different geophysical methods such as electrical resistivity imaging and multichannel analysis of surface waves can provide distributions of resistivity and shear velocity which are responsible for the underground physical parameters. Their joint interpretation can solve individual problems of none-uniqueness of the solutions when expressing two inversion results to describe environment characteristics. In our work, the k-means clustering method can categorize the two parameters into specific zones that can help to interpret the geophysical data effectively. Our workflow consists of two stages in which two independent geophysical data are inverted and the k-means clustering is applied to the two results for achieving the specified groups. The collocated geophysical data are measured in District 9, Ho Chi Minh City, Vietnam. Matching with the geology drillhole information, the joint results generally present layered medium with the upper zone having smaller resistivity and shear velocity values and the bottom zone of stronger stiffness.

PL

Bezpieczeństwo konstrukcji wymaga znajomości parametrów fizycznych, takich jak sztywność czy porowatość środowiska podpowierzchniowego. Połączenie różnych metod geofizycznych, takich jak obrazowanie rezystywności elektrycznej i wielokanałowa analiza fal powierzchniowych, może dostarczyć rozkłady rezystywności i prędkości ścinania, które są odpowiedzialne za parametry fizyczne podziemnych warstw. Ich wspólna interpretacja może rozwiązać indywidualne problemy niejednoznaczności rozwiązań przy wyrażaniu dwóch wyników inwersji do opisu cech środowiska. W naszej pracy metoda grupowania k-średnich może podzielić dwa parametry na określone strefy, co może pomóc w skutecznej interpretacji danych geofizycznych. Nasz przepływ pracy składa się z dwóch etapów, w których dwa niezależne dane geofizyczne są odwracane, a grupowanie k-średnich jest stosowane do dwóch wyników w celu uzyskania określonych grup. Zebrane dane geofizyczne są mierzone w Dystrykcie 9, Ho Chi Minh City, Wietnam. Dopasowując się do informacji uzyskanych z odwiertów geologicznych, wyniki połączeń ogólnie przedstawiają ośrodek warstwowy, w którym górna strefa ma mniejsze wartości rezystywności i prędkości ścinania, a dolna strefa ma większą sztywność.

2

3D subsoil reconstruction of a mud volcano in central Sicily by means of geophysical surveys

Grassi Sabrina, De Guidi Giorgio, Patti Graziano, Brighenti Fabio, Carnemolla Francesco, Imposa Sebastiano

Acta Geophysica

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2022

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Vol. 70, no 3

1083--1102

EN

The upwelling of fluids, subject to overpressure, along with discontinuities in the subsoil, causes the formation of geological structures known as mud volcanoes. These structures, very widespread in the world and in some cases located near inhabited centers, can represent a considerable risk factor for the population, as they can give rise to paroxysmal eruptions, even very violent. The assessment of the characteristics and structure of the subsoil of the areas affected by this phenomenon can prove to be a useful tool for risk mitigation. Non-invasive geophysical surveys were carried out in the area of the active cone of the Santa Barbara mud volcano in order to obtain a 3D characterization of the subsoil. Through the processing and integration of data derived from active and passive seismic surveys was obtained, a 3D model showing the seismostratigraphic subsoil structure. The electrical resistivity tomography surveys provided results comparable to those obtained from seismic surveys and supplied information on the perimetral areas of the mud volcano. The information obtained is useful to study the boundary conditions that influence short-scale activity. Furthermore, this study seeks to evaluate the possibility of using the proposed methodological approach for monitoring the variations that occur over time in the areas affected by mud volcanoes phenomenon.

3

Comparison of MASW and seismic interferometry with use of ambient noise for estimation of S‑wave velocity field in landslide subsurface

Harba Paulina, Pilecki Zenon, Krawiec Krzysztof

Acta Geophysica

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2019

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Vol. 67, no. 6

1875--1883

EN

This study presents a comparison of data acquisition, processing and interpretation between passive seismic interferometry (SI) and active multichannel analysis of surface waves (MASW) methods, both using surface waves for estimation S-wave velocity field. Measurements have been taken in the same geological engineering conditions on Just-Tegoborze landslide on the south of Poland. This comparison study has an important meaning from landslide hazard evaluation point of view. The landslide is located in Magura Nappe in Outer (Flysch) Carpathians. SI was based on registration of local seismic noise generated by high traffic on the state road which intersects the landslide. The main processing step was cross-correlation of seismic noise between every pair of receivers. It led to obtain series of empirical Green’s functions for Rayleigh surface wave. However, in MASW method, seismic energy was released by an impact of 5 kg sledgehammer in a metal plate. Both methods included analysis of dispersion curves of Rayleigh surface wave. The inversion of picked fundamental modes was applied using genetic algorithm and resulted in 1D S-wave velocity models. The last step of interpretation included model visualization as the 2D S-wave velocity sections for studied profiles. Both MASW and SI methods allowed to estimate S-wave velocity field in Just-Tegoborze landslide subsurface. Dispersion images obtained from both methods provided similar phase velocity and frequency ranges. On S-wave velocity sections, the greater depth range was observed for SI method; however, lateral resolution was better for MASW. Slip surfaces in colluvial layer were not observed on either SI or MASW S-wave velocity sections. Only results obtained from SI allowed to distinguish probable slip surface located deeper, i.e. on the contact with less weathered flysch bedrock.

4

The investigation of soil–structure resonance of historical buildings using seismic refraction and ambient vibrations HVSR measurements: a case study from Trabzon in Turkey

Babacan A. E., Akın Ö.

Acta Geophysica

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2018

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Vol. 66, no. 6

1413--1433

EN

In this study, two different historical structures built in Trabzon have been processed by ambient vibrations and seismic refraction measurements. One of the investigated historical structures is the Atatürk Pavilion built in the nineteenth century, and the other one is Hagia Sophia which was built in the thirteenth century. These two buildings are among the most important historical buildings in Trabzon and are very important for the tourism of the city. In order to determine peak/s frequency and amplitude from the horizontal-to-vertical spectral ratios (HVSRs), we have performed several measurements of ambient vibrations both inside (at different floors) and outside (on the ground) of structures. We have also conducted seismic prospecting to evaluate the vertical 1D and 2D profile of longitudinal and shear seismic waves, Vp and Vs, respectively. To this purpose, we have performed seismic refraction tomography and MASW. Ambient vibrations and seismic measurements were compared with each other. The results show that average predominant frequencies and HVSR amplitudes of inside and outside of Atatürk Pavilion are 4.0 Hz, 7.8 Hz and 2.6, 2.3, respectively. The Vp values vary from 300 to 2070 m/s, and the Vs for maximum effective depth is up to 790 m/s in Atatürk Pavilion. On the other hand, average predominant frequencies and HVSR amplitudes of inside and outside of Hagia Sophia and its tower are 4.7, 4.4 and 2.4 Hz and 1.6, 1.8 and 6.9, respectively. Vp values range from 450 to 2200 m/s, and Vs for maximum effective depth is also up to 1000 m/s in Hagia Sophia. The frequency values (F0 = Vs/4 h) calculated from the velocities up to the maximum effective depth for Atatürk Pavilion are in good agreement with the predominant frequency values determined from ambient vibrations. Atatürk Pavilion and Hagia Sophia soils have been classed according to Eurocode 8 by using VS30 values. The class was defined as “B.” Moreover, the bedrock in studied area is basalt. The high Vp and Vs values are also compatible with the lithology. The HVSR curves measured at the Hagia Sophia show the presence of clear peaks when compared to the Atatürk Pavilion. At the same time, there are marked velocity changes in the Vs sections calculated in both areas. As a result, in both areas there are significant impedance contrasts in the subsoil. However, this impedance contrast is more evident in Hagia Sophia. This could be also compatible with a lithological transition. The possible soil–structure interaction was investigated by using all the results and evaluated in terms of resonance risk. It is thought that the probability of resonance risk at Atatürk Pavilion is low according to the ambient vibrations measurements. However, resonance risk should be taken into consideration at Hagia Sophia site since the predominant frequency values are very close to each other. Finally, this site should be investigated in detail and necessary precautions should be taken against the risk of resonance.

5

Geological and seismic investigation of former lignite mining area in Zielona Góra – two case studies

Gontaszewska-Piekarz A., Kłosiński J.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

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2017

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z. 64, nr 2/I

311--326

EN

The article presents two case studies of investigation carried out on plots of land, intended for multi-family residential development, lying on a former lignite mining area in Zielona Gora. It was underground mining, operating in the years 1840- 1948. Lignite deposits were extracted with the room and pillar method, i.e. with an overlayer collapse, causing deformations on the surface of the ground. In the first case study, there was no detailed mining data. In order to identify the geological structure under the planned seven-floor multi-family building, seismic surveys were performed with the technique of multichannel analysis of surface waves (MASW). Three seismic profiles were performed. They revealed the presence of several zones where S-waves had smaller velocity values. In order to verify whether the zones with the smaller values of velocity correspond to e.g. lower soil density resulting from collapsed exploitation room, some drillings were undertaken to the depth indicated in geophysical investigation. Additionally, the CPT and dynamic probing were also performed. The data obtained allowed to determine the soil parameters necessary for the safe design and foundation of the building. In the second case study, a historical mining map with the marked location of the shaft and the main galleries was used. Formerly, geological and engineering documentation for construction works had been prepared, based on 30-meter drillings and soundings with a heavy probe. The mining maps and the contemporary maps were mapped one on another carefully and accurately, calibrated with historic buildings. Thus, the accuracy of 5 m was obtained. Additionally, investigation with the MASW technique was performed. Ten seismic profiles were performed, and then verified by drillings. Also, dynamic probing in the vicinity of the expected location of the shaft was performed. Neither the MASW investigation nor the dynamic probing did not reveal any alterations in the soil condition, which would suggest the presence of the properly liquidated shaft. Thus, based exclusively on the cartographic material, the area comprising the liquidated and backfilled shaft was established. The area was excluded from the plans for the intended building erection.

PL

Artykuł przedstawia badania, jakie przeprowadzono na dwóch przykładowych działkach przeznaczonych dla zabudowy wielorodzinnej leżących na terenie dawnego górnictwa węgla brunatnego w Zielonej Górze. Było to górnictwo podziemne, działające w latach 1840-1948. Węgiel 326 A. Gontaszewska-Piekarz, J. Kłosiński brunatny eksploatowany był metodą filarowo – komorową, na zawał, powodując powstawania na powierzchni deformacji terenu. Dla niektórych fragmentów miasta zachowały się mapy górnicze. W pierwszym przypadku brak było szczegółowych danych górniczych. W celu rozpoznania budowy geologicznej pod projektowany budynek wielorodzinny, 7-kondygnacyjny wykonano geofizyczne badania sejsmiczne techniką wielokanałowej analizy fal powierzchniowych MASW. Wykonano 3 profile sejsmiczne. Wykazały one kilka niewielkich stref cechujących się niższymi wartościami prędkości fal sejsmicznych poprzecznych S. W celu weryfikacji, czy strefy obniżeń prędkości związane są np. z obniżonym zagęszczeniem gruntu wskutek zawału stropu nad komorami eksploatacyjnymi wykonano odwierty do głębokości wskazanej badaniami geofizycznymi. Wykonano także sondowania sondą CPTu oraz sondowania dynamiczne. Uzyskane dane pozwoliły na określenie parametrów podłoża koniecznych do bezpiecznego zaprojektowania posadowienia budynku. W drugim przypadku dostępna była mapa górnicza z lokalizacją szybu oraz głównych chodników.

6

Application of Multichannel Analysis of Surface Waves to S-Phase Wave Anisotropy Estimation

Stan-Kłeczek I., Mendecki M. J.

Acta Geophysica

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2016

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Vol. 64, no. 5

1593--1604

EN

The Multichannel Analysis of Surface Waves (MASW) is an increasingly used technique for recognition of a shallow geological structure and estimation of geotechnical parameters, e.g., S-wave velocity, layer density, layer thickness, shear modulus, estimated P-wave velocity, and estimated Poisson ratio. MASW surveys were carried out in two limestone quarries in the southern part of Poland. The experimental areas are characterised by a simple geological structure: consolidated Triassic limestone. Measurement profiles were arranged as a shapely six-pointed star. For each survey line, 12 geophones with 2-meter (Deposit 1) and 3-meter (Deposit 2) spacing were applied. The research allowed to compare P- and S-wave velocity changes with the main crack systems in the studied rock masses.

7

Evaluation of the state of sandy soils on a sinkhole area with the use of noninvasive (MASW) and invasive (SDMT) tests

Szajna W. S.

Engineering Transactions

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2015

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Vol. 63, iss. 1

109--131

EN

The subject of the study is to assess the state of soil in the area of a former shallow underground mining site which presents a potential hazard of sinkholes. Two kinds of tests were performed i.e. noninvasive seismic tests MASW and invasive seismic dilatometer tests SDMT. The test procedures and the used equipment are described in the paper. The MASW tests allowed the detection of shallow and deep seismic anomalies – places with reduced mechanical parameters. Shallow anomalies were subjected to SDMT tests. Stiffness parameters were adopted as a measure of the state of soil. The applied consistent methodology allowed for the assessment of soil stiffness for intermediate and very small strains. It has been shown that the shallow anomalies were not caused by sinkhole processes. The values of stiffness for intermediate and very small strains in the zone above shallow anomalies occurred to be inconsistent, suggesting the influence of cementation or desiccation processes.

8

Możliwości oceny stanu technicznego wałów przeciwpowodziowych na podstawie badań geofizyki inżynierskiej

Ostrowski S., Lasocki M.

Przegląd Geologiczny

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2014

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Vol. 62, nr 10/2

671--679

EN

Catastrophic floodings caused by floodbank and dam failures draw attention to urgent need of modernization of these facilities in Poland. The task specified above requires precise and fast methods of technical condition assessment of existing facilities. Present method of assessment of the geotechnical parameters of flood embankments and its geological setting is limited to sampling and geotechnical probing in discrete intervals, which are too sparse to recognize zones of weakening or unfavourable geologic conditions that might constitute critical zones for floodbank stability. This paper presents results and conclusions of experimental survey concluded in 2014 attempting to apply near-surface geophysical methods to floodbank condition assessment. In author's opinion, three techniques applied yielded most reliable results. Moreover the methods – electric resistivity tomography; seismic refraction tomography and multichannel analysis of surface waves can be optimised for utilisation for fast surveys on floodbanks. Authors give attention to results of above mentioned three geophysical methods and only briefly discuss the applicability of other near-surface geophysical methods for issues concerning floodbank technical condition.

9

The Possibility of Setting Dynamic Shear Modulus Based on Multi-Channel Analysis of Surface Waves

Matula R., Czaja K., Ślusarczyk R.

Logistyka

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2014

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nr 4

4658--4664, CD6

EN

Considering logistic as a process of planning, implementing and controlling the efficient and cost-effective flow of raw materials, finished products and relevant information from point of origin to point of consumption it must be stated that effective transport is an indispensable factor that determines the process flow of goods, services, etc. Consequently, transport depends on fact how effectively net of highway is constructed, providing the best possible solution to the movement of goods and services. Design of roads and highways that are without doubt the basics of logistics activities depends on many factors, which at first glance do not have much to do with logistics in the proper sense of this word. Post designate the route of the road or highway seems to be a strategic issue both from a technical point of view as well as its subsequent exploitation. Construction of the road network in the simplest, possible way consist of building roads along as straight lines as possible. But it may be difficult to implement be-cause of many reasons. Variable environmental conditions are one of the causes that contribute to changes in the originally assumed location of the investment, which entails significant costs. Non-invasive seismic survey can be an answer for series of questions related to the stability of the ground, before the start of the investment. Results of seismic measurements can be converted to the dynamic mod-ulus of elasticity. The article presents description of possibilities of evaluation shear modulus in Holocene sediments from seismic measurements.

PL

Biorąc pod uwagę logistykę jako proces planowania, wdrażania i kontrolowania sprawnego oraz efek-tywnego przepływu surowców, wyrobów gotowych oraz odpowiedniej informacji z punktu pochodzenia do punktu konsumpcji, należy stwierdzić, że sprawny transport jest niezbędnym czynnikiem, który decyduje o płynności przepływu towarów, usług, itp. Zależy on od konstrukcji sieci dróg i autostrad, które powinny zapewniać najlepsze z możliwych rozwiązanie dla przepływu towarów i usług. Projektowanie dróg i autostrad, na których opiera się szereg działań logistycznych, zależy od wielu czynników, które na pierwszy rzut oka nie mają wiele wspólnego logistyką w ścisłym znaczeniu tego słowa. Proces wyzna-czenia trasy drogi lub autostrady wydaje się być strategicznym problemem zarówno z punktu widzenia technicznego, jak i jej późniejszego wykorzystywania. Budowa sieci dróg w najprostszy z możliwych sposobów, tzn. w postaci zbliżonej do linii prostej, może być trudne w realizacji z wielu powodów. Jedną z przyczyn są zmienne warunki naturalne, które przyczyniają się do zmian w pierwotnie założonej lokalizacji inwestycji, co pociąga za sobą znaczne koszty. Odpowiedzą na szereg pytań związanych ze stabilnością podłoża przed rozpoczęciem właściwej inwestycji mogą być badanie sejsmiczne. Wyniki tych badań mogą być przeliczone na wartości dynamicznych modułów sprężystości.

10

Save and Stable Highways by Non-Invasive Seismic Monitoring

Matuła R.

Logistyka

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2013

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nr 4

EN

In the modern world the net of highways in every country seems to be a blood vessel of alive industry organism. Fast and efficient transport depends on conditions of roads which are commonly overloaded by arising heavy motor traffic. Intensive exploitation of motorways induces damaging their embankments especially by strong vibration from trucks. Initially, local weaknesses in mechanical properties of material comprising road body spreads on larger area, mostly by process of liquefaction. In answer of transport needs this paper shows proposal of non-invasive road condition assessment using Multichannel Analysis of Surface Waves (MASW).

PL

Obecnie sieć autostrad, niezależnie od rozważanego kraju, stanowi skomplikowany układ elementów infrastruktury komunikacyjnej. Szybki i efektywny transport jest bezpośrednio zależny od stanu dróg, których obciążenie sukcesywnie narasta. Ich intensywna eksploatacja powoduje nieuchronną destrukcję nasypów drogowych bądź autostradowych, której przyczyną są zarówno czynniki naturalne jak i wibracje pochodzące bezpośrednio od ruchu drogowego. Początkowo niewielkie ubytki w prawidłowo wykonanym nasypie - a dokładniej precyzując, jego właściwościach mechanicznych, stale przyrastają przyczyniając się do zniszczenia powierzchni jezdni. Dbałość o wspomnianą infrastrukturę nie polega jedynie na usuwaniu powstałych uszkodzeń, ale na dostarczaniu w sposób ciągły informacji o jej stanie. Treścią niniejszego artykułu jest przedstawienie narzędzia sejsmiki inżynierskiej – Wielokanałowej Analizy Fal Powierzchniowych, w zastosowaniu do szacowania stanu technicznego nasypów autostradowych.

11

Seismic characterization of an abandoned mine site

Arosio D., Longoni L., Papini M., Zanzi L.

Acta Geophysica

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2013

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Vol. 61, no. 3

611--623

EN

The near-surface rock structure that covers an abandoned marl mine nearby the village of Montevecchia (Italy) was investigated through a combination of seismic surveys. The methods selected for these investigations were refraction seismics and multichannel analysis of surface waves (MASW). A sort of transillumination experiment was also attempted. All the methods were successful and gave complementary information. Refraction seismics was used to characterize the upper low velocity layer and the second layer of the near-surface structure. The MASW method was necessary to assess the existence of a velocity inversion revealing the presence of a low velocity layer between the 2nd layer and a 4th high velocity layer covering the upper mine gallery. The transillumination experiment validated the presence of the 4th layer and gave an estimate of the average velocity that represents a lower boundary for the P-wave velocity within this layer. Both the refraction and transillumination data were analysed to derive average estimates of attenuation level and rock quality factor.

12

Subsurface velocity model in post-glacial deposits based on multichannel analysis of surface waves

Matula R., Lewińska P.

Geology, Geophysics and Environment

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2012

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Vol. 38, no. 4

505

EN

First introduced and developed in the 1990s, the multichannel analysis of surface waves (MASW) is one of the active, seismic methods created for shallow seismic imaging. Surface waves generated from a sledge hammer were used for delineation of subsurface structures. MASW is analyzing the propagation velocities for each component of surface waves by generating the dispersion curves, and then as a result produces shear-wave velocity (Vs) profiles below the surveyed surface. A Vs distribution in the depth domain is obtained in 1-D or 2-D variant after a quite simple inversion procedure. Shear-wave velocity iVs) is one of the elastic constants, closely related to changes in geology. Weathering zone in post-glacial area, as one of the most complex geological forms, were chosen to check MASW ability to evaluation near-surface, folded structures. Data were acquired for typical MASW continuous profiling schema in 2 meters intervals and performed using land-streamer at the distance of about 200 m, along previously existed reflection seismic line. The analysis was supported by records from previously made reflection seismic investigations. Image of glacial till on MASW 2-D map is characterized by appearance of mix clay-sandy layers, folded and locally discontinued. Furthermore, the most of detected middle layers from 0 m up to 30 m deep form pile of thrust slices. Application of obtained subsurface model could be considered at a two main stages. First of them has a geological background where continuous Vs distribution supporting geological and geomorphological works. The second one is connecting with prospecting seismic where 2-D Vs map could be used for static purposes.

13

Wykrywanie pustek w podłożu pod obiektami budowlanymi na podstawie badań geofizycznych metoda sejsmiczną – techniką MASW

Jędruś Rafał, Kłosiński Jerzy

Zeszyty Naukowe Wyższej Szkoły Technicznej w Katowicach

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2011

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nr 3

49--56