Study of Ground Investigation Data along the Brunei Temburong Bridge Alignment

2021 ◽  
pp. qjegh2021-002
Author(s):  
Yogerej Visvanathan ◽  
Stefan Herwig Gödeke
Keyword(s):  
Cross Sections ◽  
Sedimentary Rocks ◽  
Geophysical Methods ◽  
Standard Penetration Test ◽  
Rock Quality Designation ◽  
Borehole Data ◽  
Rock Quality ◽  
Ground Investigation ◽  
Ground Conditions ◽  
Investigative Techniques

The Brunei Temburong Bridge (BTB) is an iconic project connecting Brunei Muara and Temburong districts in Brunei over a length of 30 km. The bridge crosses from Brunei Muara across Brunei Bay to Temburong. A key aim of the BTB project was the development of Temburong district, being prior the more isolated district, because of not having a direct land link to the other districts. This study reviews the geology of soil materials and sedimentary rocks along the bridge alignment based on 164 boreholes drilled for ground investigation. Standard Penetration Test, Rock Quality Designation and Fracture Index data were evaluated to interpret soil materials and sedimentary rocks along the alignment. Borehole data was used to generate lithological cross sections along the alignment providing an overview of geology. The geology encountered is extremely heterogenous, with low strength sediments encountered at depth of up to 80 m and more e.g., at the Temburong section. Rock quality designation vs. Fracture Index did not show a strong correlation likely due to the extreme heterogeneity in particular for the Brunei Bay and Temburong sections. The study demonstrates the importance of a closely spaced investigative drilling and sampling program for major construction programs which was successfully achieved for this project. Other investigative techniques such as geophysical methods could be highly useful for future projects. Considering economic and environmental reasons these techniques could be very useful to map the top of the bedrock even under highly heterogeneous ground conditions.

scholarly journals KUAT TARIK ANGKER KANTILEVER DENGAN METODE PENDEKATAN JRC (STUDI KASUS JALAN KANTILEVER KM. 461+480 TAPAKTUAN)

2018 ◽  
Vol 1 (3) ◽  
pp. 647-656
Author(s):  
Jumaidi Jumaidi ◽  
Munirwansyah Munirwansyah ◽  
Sofyan M. Saleh
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Safety Factor ◽  
Standard Penetration Test ◽  
Rock Quality Designation ◽  
Penetration Test ◽  
Loading Test ◽  
Rock Quality ◽  
Ground Anchor ◽  
Cut And Fill

Abstract: The Tapaktuan-Bakongan is the national road access to the South-West part of Aceh. Topographically shows that the road consist of canyon and a very steep cliff, which will be impossible to build more infracstructure using either blasting or cut and fill method with heavy equipment. Referring to the situation, the study about anchor tensile strength, which is used in construction of road access expansion using cantilever method is conducted. The research methode is begin by collecting the real data which are Standard Penetration Test data (SPT) SNI 4153-2018 and tensile graund anchor proving test (Bristish Satndard 8081:1981) and geological data taken from SPT drilling data. Furthermore, the data involved N-SPT, Joint Roughness Coefficient (JRC), shear stress will be analyzed and yield loading test value. Finally, from the loading test value, the reseacher will evaluate the stability of tensile capacity and safety factor (SF) of ground anchor. From the data analysis obtained that rock mass of STA 1+ 280 or KM. 461 +480 geologically contain unrigid and very strong limestone with N-SPT value greater than 50 where the rock condition is solid concrete and could be crushed using blasting method. Five samples are taken from the 10 meters driling for the laboratory test and obtain the minimum compressive strength is 51,10 MPa and maximum is 103,89 MPa with JRC from 2 to 20. In addition, the rock quality designation (RQD) calculation yield the average stone quality is 60,8% which means the rock has medium quality. Ground anchor failure if the proving test over 80% UTS(ultimate tensile strength)   i.e. the load increment reaches 92,55% UTS or 54 MPa. Therefore, the proving test maximum capacity for ground anchor is 54 Mpa and safety factor is 1,85 which are suitable to geological condition research area.Abstrak: Ruas jalan Tapaktuan – Bakongan merupakan ruas jalan nasional lintas Barat – Selatan Aceh. Kondisi topografi ruas jalan terdiri dari tebing yang terjal dan lereng yang curam sehingga tidak memungkinkan dilaksanakan pelaksanaan kontruksi pembangunan/peningkatan dengan metode blasting (penggunaan bahan peledak) maupun metode cut and fill yang menggunakan alat-alat berat. Dari permasalahan tersebut dilakukan sebuah kajian mengenai kuat tarik angker yang digunakan pada pelaksanaan pembangunan pelebaran badan jalan dengan menggunakan metode kantilever untuk daerah dengan kondisi topograsi tebing yang terjal dan lereng yang curam. Metode yang diterapkan pada penelitian ini diawali dengan pengumpulan data riil yang meliputi data Standard Penetration Test (SPT) SNI 4153-2008 dan uji tarik proving test ground anchor (British Standard 8081:1981) dan data geologi yang dihasilkan dari data pengeboran SPT. Selanjutnya dari data-data yang diperoleh dilakukan analisis data yang meliputi analisis nilai N-SPT, Joint Roughnes Coefficient (JRC), gaya geser, yang menghasilkan angka loading test. Dari data hasil loading test dapat dievaluasi stabilitas kapasitas tarik dan safety factor (SF). Dari data analisis didapatkan bahwasanya kondisi geologi batuan di STA 1+ 280 atau KM. 461 + 480 terdiri dari batu gamping tidak lapuk dan sangat keras dan dapat dipecahkan dengan peledakan dengan nilai N-SPT lebih besar dari 50 dimana kondisi batuan sangat padat. Dari hasil pengeboran sepanjang 10 meter diambil lima sampel untuk di uji laboratorium dan diperoleh nilai compressive strength minimal 51,10 MPa dan maksimum 103,89 MPa dengan nilai JRC 2-20. Selain daripada itu hasil perhitungan rock quality designation (RQD) menunjukkan kualitas batuan pada lokasi kajian rata-rata 60,8% yang berarti kualitas batuannya adalah sedang. Ground anchor putus pada saat uji tarik proving test diatas pembebanan 80% UTS yaitu pembebanan sampai 92,55% UTS (ultimate tensile strength) atau sebesar 54 MPa. Dengan demikian kapasitas maksimum hasil uji tarik proving test ground anchor yaitu sebesar 54 MPa dengan faktor keamanan 1,85 sesuai dengan kondisi geologi daerah kajian.

scholarly journals Classification of cut slopes in weathered meta-sedimentary bedrocks

2016 ◽  
Vol 20 (2) ◽  
pp. 1 ◽  
Author(s):  
Johnbosco Ikenna Nkpadobi ◽  
John Kuna Raj ◽  
Tham Fatt Ng
Keyword(s):  
Rock Mass ◽  
Sedimentary Rocks ◽  
Rock Mass Rating ◽  
Rock Quality Designation ◽  
Rock Quality ◽  
Slope Mass Rating ◽  
Field Investigations ◽  
Kinematic Analyses ◽  
Cut Slopes

In order of abundance, the meta-sedimentary rocks along Pos Selim Highway in Perak state Malaysia comprise quartz mica schist, graphitic schist, and quartzite layers. Field investigations revealed that these meta-sedimentary rocks have gradational weathering profile based on differences particularly in textures, hardness, lateral changes in colour, and consistency of material extension. The results from uniaxial compressive strength tests confirmed field observations whereby failure occurred mostly on outcrops having joints almost perpendicular to foliation. From the kinematic analyses, the investigated cut slopes are unstable with possibilities of wedge and planar failures. Application of rock mass classification schemes including Rock Quality Designation (RQD) and Rock Mass Rating (RMR) yielded almost similar poor to good quality ranges for each investigated rock mass. While Slope Mass Rating (SMR) classified the cut slopes from stable to unstable slopes, this study categorized them into one actively unstable, four marginally stable and five stable slopes.  ResumenEn orden de abundancia, las rocas metasedimentarias a lo largo de la carretera Pos Selim, en el estado Perak de Malasia, se componen de esquistos de cuarzo mica, esquistos de grafito y capas de cuarzo. Las investigaciones de campo revelan que estas rocas metasedimentarias tienen perfiles de meteorización progresiva basados en diferencias particulares como textura, dureza, cambios laterales de color y consistencia del material de extensión. Los resultados de los ensayos uniaxiales de esfuerzo de compresión confirmaron las observaciones de campo por las cuales se estableció que las fallas ocurrieron mayormente en los afloramientos con coyunturas perpendiculares hacia la foliación. De los análisis cinemáticos se desprende que los taludes de corte investigados son inestables con posibilidades de fallas planas y de cuña. La utilización de esquemas de clasificación rocosa como el índice RQD (del inglés Rock Quality Designation) y la clasificación geomecánica de Bienawski o RMR (del inglés Rock Mass Rating) evidencia rangos similares de baja y buena calidad para cada masa rocosa estudiada. Mientras que el índice de taludes SMR (del inglés Slope Mass Rating) clasificó los taludes de corte de estables a inestables, este estudio los categorizó de uno activamente inestable, cuatro marginalmente estables y cinco estables.

scholarly journals Identifying Changes in Sediment Texture along an Ephemeral Gravel-Bed Stream Using Electrical Resistivity Tomography 2D and 3D

2021 ◽  
Vol 11 (7) ◽  
pp. 3030
Author(s):  
Marcos A. Martínez-Segura ◽  
Carmelo Conesa-García ◽  
Pedro Pérez-Cutillas ◽  
Pedro Martínez-Pagán ◽  
Marco D. Vásconez-Maza
Keyword(s):  
Electrical Resistivity ◽  
Cross Sections ◽  
Electrical Resistivity Tomography ◽  
Environmental Changes ◽  
Subsurface Layer ◽  
Sediment Texture ◽  
Borehole Data ◽  
Resistivity Tomography ◽  
Gravel Bed ◽  
Basin Scale

Differences in deposit geometry and texture with depth along ephemeral gravel-bed streams strongly reflect fluctuations in bedload which are due to environmental changes at the basin scale and to morphological channel adjustments. This study combines electrical resistivity tomography (ERT) with datasets from borehole logs to analyse the internal geometry of channel cross-sections in a gravel-bed ephemeral stream (southeast Spain). The survey was performed through longitudinal and transverse profiles in the upper channel stretch, of 14 to 30 m in length and 3 to 6 m in depth, approximately. ERT values were correlated with data on sediment texture as grain size distribution, effective grain sizes, sorting, and particle shape (Zingg’s classification). The alluvial channel-fills showed the superposition of four layers with uneven thickness and arrangement: (1) the softer rocky substrate (<1000 Ω.m); (2) a thicker intermediate layer (1000 to 2000 Ω.m); and (3) an upper set composed of coarse gravel and supported matrix, ranging above 2000 Ω.m, and a narrow subsurface layer, which is the most resistive (>5000 Ω.m), corresponding to the most recent armoured deposits (gravel and pebbles). The ERT results coupled with borehole data allowed for determining the horizontal and vertical behaviour of the materials in a 3D model, facilitating the layer identification.

scholarly journals Verification of geophysical models in Alpine permafrost using borehole information

2000 ◽  
Vol 31 ◽  
pp. 300-306 ◽  
Author(s):  
Daniel S. Vonder Mühll ◽  
Christian Hauck ◽  
Frank Lehmann
Keyword(s):  
Geophysical Methods ◽  
Swiss Alps ◽  
Rock Glacier ◽  
Surface Microtopography ◽  
Refraction Seismics ◽  
Geophysical Surveys ◽  
Ground Conditions ◽  
Lateral Extent ◽  
Ice Content ◽  
Difficult Terrain

AbstractAt two permafrost sites in the Swiss Alps a range of geophysical methods were applied to model the structure of the subsurface. At both sites, borehole information was used to verify the quality of the model results. On the Murtèl-Corvatsch rock glacier (2700 m a.s.L; upper Engadine) a 58 m deep core drilling was performed in 1987. D. c resistivity measurements, refraction seismics, ground-penetrating radar (GPR) and gravimetric surveys allowed the shape of the permafrost table beneath the marked surface microtopography to be determined and the lateral extent of a deeper shear horizon to be established The validity of each method was verified by the borehole information (cores, density log and temperature). A coherent model of the rock-glacier structure was developed. At the Schilthorn (2970 m a.s.L; Bernese Oberland), it was not clear whether permafrost is in fact present. Various geophysical surveys (d.c. resistivity tomography, refraction seismics, GPR and EM-31) gave results that were not typical of permafrost environments. A 14 m percussion drilling revealed warm permafrost and a very low ice content. These geotechnical and geothermal data allowed reinterpretation of the geophysical results, improving modelling of ground conditions. The paper demonstrates that in the difficult terrain of Alpine permafrost, boreholes may be critical in calibration and verification of the results of geophysical methods. The most useful combinations of geophysical techniques proved to be (a) seismics with d.c. resistivity, and (b) gravimetry with GPR.

scholarly journals Relief evolution of landslide slopes in the Kamienne Mts (Central Sudetes, Poland) – analysis of a high-resolution DEM from airborne LiDAR

2018 ◽  
Vol 7 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Aleksandra Osika ◽  
Małgorzata Wistuba ◽  
Ireneusz Malik
Keyword(s):  
Cross Sections ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Airborne Lidar ◽  
Lidar Data ◽  
Mountain Ridge ◽  
Geological Maps ◽  
Different Types ◽  
Sw Poland ◽  
Landslide Development

Abstract The aim of the study is to reconstruct the development of landslide relief in the Kamienne Mountains (Central Sudetes, SW Poland) based on a DEM from LiDAR data. Analyses of relief and geological maps in ArcGIS 10.5 and of slope cross-sections in Surfer 14 allowed to distinguish different types of landslide relief, developed in latites and trachybasalts lying above claystones and mudstones. The types vary from small, poorly visible landslides to vast landslides with complex relief. They were interpreted as consecutive stages of geomorphic evolution of hillslope-valley topography of the study area. Two main schemes have been established which explain the development of landslide slopes in the Kamienne Mts: (1) upslope, from the base of the slope towards the mountain ridge and (2) downslope, beginning on the top of the mountain ridge. The direction of landslide development depends on the thickness of volcanic rocks in relation to underlying sedimentary rocks. When the latter appear only in the lowest part of the slope, landslides develop upslope. If sedimentary rocks dominate on the slope and volcanic rocks form only its uppermost part, landslides develop downslope. The results show that landsliding leads to significant modifications of relief of the study area, including complete degradation of mountain ridges.

scholarly journals Hydrogeological characterisation of a glacially affected barrier island – the North Frisian Island of Föhr

2012 ◽  
Vol 9 (4) ◽  
pp. 5085-5119 ◽  
Author(s):  
T. Burschil ◽  
W. Scheer ◽  
R. Kirsch ◽  
H. Wiederhold
Keyword(s):  
North Sea ◽  
Underground Structure ◽  
Empirical Relation ◽  
Geophysical Methods ◽  
Strong Impact ◽  
Hydrogeological Model ◽  
Borehole Data ◽  
The North ◽  
The North Sea ◽  
D Model

Abstract. We present the application of geophysical investigations to characterise and improve the geological/hydrogeological model through the estimation of petrophysical parameters for groundwater modelling. Seismic reflection and airborne electromagnetic surveys in combination with borehole information enhance the 3-D geological model and allow a petrophysical interpretation of the subsurface. The North Sea Island of Föhr has a very complex underground structure what was already known from boreholes. The local waterworks use a freshwater body embedded in saline groundwater. Several glaciations disordered the Youngest Tertiary and Quaternary sediments by glaciotectonic thrust-faulting as well as incision and refill of glacial valleys. Both underground structures have a strong impact on the distribution of freshwater bearing aquifers. An initial hydrogeological model of Föhr was built from borehole data alone and was restricted to the southern part of the island where in the sandy areas of the Geest a large freshwater body was formed. We improved the geological/hydrogeological model by adding data from different geophysical methods, e.g. airborne electromagnetics (EM) for mapping the resistivity of the entire island, seismic reflections for detailed cross sections in the groundwater catchment area, and geophysical borehole logging for calibration of these measurements. An integrated evaluation of the results from the different geophysical methods yields reliable data. To determinate petrophysical parameter about 18 borehole logs, more than 75 m deep, and nearby airborne EM inversion models were analyzed concerning resistivity. We establish an empirical relation between measured resistivity and hydraulic conductivity for the specific area – the North Sea island of Föhr. Five boreholes concerning seismic interval velocities discriminate sand and till. The interpretation of these data was the basis for building the geological/hydrogeological 3-D model. We fitted the relevant model layers to all geophysical and geological data and created a consistent 3-D model. This model is the fundament for groundwater simulations considering forecasted changes in precipitation and sea level rise due to climate change.

Geoprocessing Techniques for the Visualization of Subsurface Geologic Data in Geographic Information Systems

2021 ◽  
Author(s):  
Nathan D. Williams
Keyword(s):  
Cross Sections ◽  
Geographic Information ◽  
3D Gis ◽  
Borehole Data ◽  
Plan View ◽  
Commercial Off The Shelf ◽  
Gis Software ◽  
2D And 3D ◽  
Geologic Data ◽  
Geologic Information

ABSTRACT The ability to visualize subsurface geologic information is critical to sound decision making in many disciplines of geology. While there are numerous commercial off-the-shelf software solutions available to model geologic data in both 2D and 3D, these can be costly and have a steep learning curve. Some of the same functionality of these software packages can be accomplished by workflows that incorporate built-in geoprocessing tools of Geographic Information System (GIS) software. These workflows allow the geologist to plot vertical or inclined borehole data in 2D or 3D, create section views of raster data along section lines, and provide a means to convert contact elevations from existing geologic cross sections into plan-view or 3D space. These workflows have been successfully used to visualize construction data and subsurface geologic information for several embankment dams. Grouting and exploratory borehole data from databases with tens of thousands of records have been transformed into 2D and 3D GIS features. The workflows were instrumental in developing a 3D GIS model of site geology from which a series of geologic cross sections were drawn. These sections were critical in informing risk decisions related to the foundation conditions for a recent risk assessment of an earthen embankment dam.

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