Soil Stratigraphy Research Articles

Field axial cyclic loading tests of screw micropiles in cohesionless soil

Screw micropile is a new type of steel pipe pile that consists of a smooth, threaded segment and a tapered segment. It is installed using the torque method. To examine the axial cyclic behavior of the piles, six one-way compressive and load-controlled axial cyclic tests were performed at a sandpit site. The axial cyclic load, with 15 cycles and an equivalent peak vertical acceleration ranging from 0.4 g to 0.6 g, was meant to replicate the vertical motion of an earthquake load. In-situ geotechnical investigation and lab testing were undertaken to determine the soil stratigraphy and properties. Three of the piles were instrumented with strain gauge to measure the unit shaft distribution. The pile-head cumulative displacement, stiffness and equivalent damping ratios were obtained. The effect of initial factor of safety on the cyclic behavior was examined. The re-distribution of unit shaft resistance of individual segments was obtained. Segment equivalent damping ratio and stiffness of the unit shaft resistance hysteresis were determined. The contribution of each pile segment to global pile behavior was delineated.

Mapping Groundwater Seepage in a Fen Using Thermal Imaging

The transport of dissolved minerals and groundwater flow plays a crucial role in the ecosystem of many wetlands. Nonetheless, installing equipment to monitor groundwater seepage is invasive, harms vegetation, and can impact biodiversity. By remotely mapping surface temperature in late summer, when there is the greatest difference between warm soil and cold groundwater, temperature patterns can expose areas with the greatest upward gradient and flow. The conventional method of using tensiometers to measure hydraulic gradient and estimate flux using Darcy’s law was applied and compared with thermal imaging to characterize groundwater seepage at two contrasting sites within a central North Dakota fen (groundwater discharge wetland). Both sites exhibited variable gradients between the shallow and deep tensiometers. The temperature trend determined from the thermal imaging showed a closer relationship to the measured hydraulic gradients at the herbaceous (Sedge) site than at the wooded (Willow) site. Saturated hydraulic conductivity K ranged from 6 × 10−5 to 2 × 10−4 m/s for the Willow site; and 6 × 10−6 to 1 × 10−4 m/s for Sedge site. The flux calculated for the Willow site ranged from 1.4 × 10−5 to 2.7 × 10−4 m/s and that of the Sedge site ranged from 2.2 × 10−6 to 6.3 × 10−5 m/s. The gradients are affected at shallow depth because of heterogeneous soil stratigraphy, which is likely the reason that seepage faces at the sites cannot be mapped solely by thermal imaging.

A computational workflow for rupture‐to‐structural‐response simulation and its application to Istanbul

AbstractScenario‐based earthquake simulations at regional scales hold the promise in advancing the state‐of‐the‐art in seismic risk assessment studies. In this study, a computational workflow is presented that combines (i) a broadband Green's function‐based fault‐rupture and ground motion simulation—herein carried out using the “UCSB (University of California at Santa Barbara) method”, (ii) a three‐dimensional physics‐based regional‐scale wave propagation simulation that is resolved at Hz, and (iii) a local soil‐foundation‐structure finite element analysis model. These models are interfaced with each other using the domain reduction method. The innermost local model—implemented in ABAQUS—is additionally enveloped with perfectly matched layer boundaries that absorb outbound waves scattered by the structures contained within it. The intermediate wave propagation simulation is carried out using Hercules, which is an explicit time‐stepping finite element code that is developed and licensed by the CMU‐QUAKE group. The devised workflow is applied to a km region on the European side of Istanbul, which was modeled using detailed soil stratigraphy data and realistic fault rupture properties, which are available from prior microzonation surveys and earthquake scenario studies. The innermost local model comprises a chevron‐braced steel frame building supported by a shallow foundation slab, which, in turn, rests atop a three‐dimensional soil domain. To demonstrate the utility of the workflow, results obtained using various simplified soil‐structure interaction analysis techniques are compared with those from the detailed direct model. While the aforementioned demonstration has a limited scope, the devised workflow can be used in a multitude of ways, for example, to examine the effects of shallow‐layer soil nonlinearities and surface topography, to devise site‐ and structure‐specific seismic fragilities, and for calibrating regional loss models, to name a few.

Impact of Local Site Conditions on the Seismic Response of the Athenian Acropolis Hill

In the literature, records and analyses have shown that in earthquake-prone areas local site conditions tend to alter the strong motion at the ground surface. More specifically, the surface topography, in combination to the soil stratigraphy and/or the geomorphology of the seismic bedrock, may have a substantial impact on the amplitude, the frequency content, and/or the duration of the seismic motion at the ground surface. The current study is involved with the Athenian Acropolis Hill, which is an unusual case of local site conditions affecting ground motion as a rock outcrop of limestone overlies the relatively soft Athenian schist. Since monuments of paramount importance are founded on the Hill (i.e. Parthenon, Propylaea, Erechtheion and Temple of Athena Nike) and Athens is characterised by moderate to high seismicity, a seismic array of accelerographs has been installed by the National Observatory of Athens and the Acropolis Restoration Service at specific locations on the Hill in order to monitor its seismic response in real time. Aiming to assess the impact of local site conditions on the seismic response of the Hill, an evaluation of the available recorded acceleration time histories has been conducted. Additionally, two-dimensional numerical simulations have been performed utilising the finite-element method. Various excitations, such as simple pulses and records obtained by the seismic array, have been used as input motion for the numerical analyses. Despite the discrepancies, the numerical results are in good agreement with the available records and demonstrate the importance of local site conditions on the seismic response of the Acropolis Hill.

Characteristics of small anthropogenic landforms resulting from historical charcoal production in western Connecticut, USA

Relict charcoal hearths (RCHs) are anthropogenic geomorphic features with an average diameter of 12 m found in many forests of Central Europe and in the eastern USA wherever pre-coal iron production took place or other industries demanded the production of charcoal. To expand the knowledge about their geoarchaeological significance and their legacy effect on soil properties and forest ecosystems, we propose a method for a generalized description of soil stratigraphy on RCHs. We studied 154 soil profiles at 52 RCH sites alongside two 1 km transects in Litchfield County, Connecticut, USA. The sites can be classified based on the slope inclination, with sites on <4° mostly having a single-layered stratigraphy and an elevated circular shape, while sites on slopes >4° mostly are built as levelled and multilayered platforms. The latter have two or more charcoal rich technogenic Auh-layers separated by intermediate Auh-layers mostly consisting of mineral substrate. Based on average layer thicknesses and their dependence on the sites slope inclinations, we propose a model with two idealized RCH shapes with slope controlled properties that allow for an easy computation of site diameters and elemental stocks. With ongoing advances in remote sensing of RCH sites, our proposed model can help to further understand the effects of historic land use on a landscape scale.

Vertical vibration of a large diameter pile partially-embedded in poroelastic soil

This paper presents an analytical study on the vibration characteristics of partially-embedded single piles subjected to vertical harmonic loads. The derived solution allows accounting for the contribution of the second-order lateral vibrations of the pile to its response, by modelling the pile as a Rayleigh-Love rod. In addition, the effects of dynamic stress-flow coupling on the propagation of ground waves resulting from pile vibrations are considered in the solution, by modelling the soil surrounding the pile shaft and underlying the pile base as poroelastic material of finite thickness. Following the verification of the derived solution against an existing solution for fully-embedded piles in single-phase soil, we investigate the effects of pile geometry and free length as well as soil stratigraphy, stiffness and flow characteristics on the response of the soil-pile system. Results of this parametric analysis suggest that ignoring the vibration characteristics of the free length of the pile can introduce significant inaccuracies in the estimation of the response for high-frequency loads, a finding that is particularly important for certain ocean and bridge engineering applications.

REVIEW OF BEARING CAPACITY AND SETTLEMENT OF PILE FOUNDATION IN PORT INFRASTRUCTURE

ABSTRACTThe rapid infrastructure development is one of the indicators on the country economic progress. Indonesia as one of the largest archipelagic countries in the world, should be prioritized the port infrastructure to support the maritime. One of the government’s solutions is infrastructure development of Kuala Tanjung port. This research analyzed bearing capacity and settlement of single and group pile foundation on port infrastructure of Kuala Tanjung so it is known that the port is safe to use. The data used are Standard Penetration Test data with soil stratigraphy that is clay and sand. The type of foundation used is Concrete Spun Pile 1000 mm and 600 mm with a pile length of 36 meters. The data are then analyzed by manual calculation and Allpile 6.5E program based on Reese method and methods such as Vesic and Converse-Labarre. The results showed that single pile foundations of 1000 mm and 600 mm each had allowable capacity (Qall) 492.78-538.81 ton and 110.65-128.31 ton, with vertical load (Q) of 330.90 ton, settlement 0.56-1.17 cm and 3.32-3.64 cm, lateral deflection 27.50 cm and 94.90 cm. While the 1000 mm and 600 mm pile group foundations respectively have Qall 8717.31-10796.29 tons and 2059.25-2566.32 tons, with Q of 6618 tons, settlement 0.56-1.68 cm and 3.32-3.64 cm, lateral deflection of 2.49 cm and 19.49 cm. The conclusion of the research indicates that the safe pile foundation used is 1000 mm group pile foundation. Keywords: Bearing Capacity; Foundations; Pile Foundation; Port Infrastructure; Settlement

DISPLACEMENT ANALYSIS OF SHEET PILE WITH TIE BEAM ON BREAKWATER CONSTRUCTION BY USING PLAXIS

The breakwater construction usually founded in coastal area with many public or company facilities. It is very useful to break the ocean waves so it can not reach the shore line. Furthermore, the breakwater construction is also applied as a barier for a port for ship docked. One of the type of breakwaters is tube column filled with compacted sand reinforced by sheet file and tie beam. This research will discuss about the sheet pile displacement in static and dynamic condition. Plaxis is applied as the main tool to built the 2-D model based on given data from field observation. The input parameter for this model is applied in soil stratigraphy, compacted sand column, sheet pile, tie beam, pseudostatic wave force, sea level and earthquake acceleration. The running of this model divided in three condition. There are static condition, static condition with pseudostatic wave force, and dynamic condition. The results show different displacement between the conditions. The sheet pile displacement in static condition is 3.35 cm at harbor side and 1.91 cm at open sea. The sheet pile displacement in static condition with pseudostatic wave force is 12.14 cm at harbor side and 12.08 cm at open sea. The sheet pile displacement in dynamic condition has 5 cm peak both harbor side and open sea.

Integrated approach for the MASW dispersion analysis using the spectral element technique and trust region reflective method

Abstract In this paper, a semi-analytical elastodynamic forward solver was proposed for the Multichannel Analysis of Surface Waves (MASW) using the spectral element technique for the first time. A root finding method based on Brent's algorithm was proposed to accurately extract the dispersion curves. The trust region reflective method, an effective bound-supported least square algorithm, was applied, for the first time, for the inversion analysis of MASW data. In comparison to the commonly used neighborhood algorithm, the proposed solver converges rapidly; the Euclidean distance between the measured and numerically calculated dispersion curves are significantly reduced within only 300 runs of the forward solver in comparison to over 10,000 runs using the neighborhood algorithm. Several numerical case studies were performed to demonstrate the selection of initial guesses as well as the bounds of each optimization parameter. Also, a parametric study was performed to determine the effect of discontinuity in the soil stratigraphy on the dispersion curves. Finally, the integrated approach developed in this study was used to analyze the MASW data collected in a site in south Iceland. It was concluded that the proposed approach determines effectively and efficiently the soil stratigraphy as well as soil properties.

Clearing a Path for Ground Heat Exchange Systems: A Review on Thermal Response Test (TRT) Methods and a Geotechnical Routine Test for Estimating Soil Thermal Properties

The performance of ground heat exchanger systems depends on the knowledge of the thermal parameters of the ground, such as thermal conductivity, capacity, and diffusivity. The knowledge of these parameters often requires quite accurate experimental analysis, known as a thermal response test (TRT). In this paper, after a general analysis of the various available types of TRT and a study of the theoretical basics of the method, we explore the perspective of the definition of a simplified routine method of analysis based on the combination of a particular version of TRT and the routine geotechnical tests for the characterization of soil stratigraphy and the ground characteristics. Geotechnical analyses are indeed mandatory before the construction of new buildings, even if limited to 30 m below the ground level or foundation base when piles are needed. The idea of developing TRT in connection with geotechnical test activity has the objective of promoting the widespread use of in situ experimental analysis and reducing TRT costs and time. The considerations presented in the present paper lead to reconsidering a particular variety of the TRT, in particular, the versions known as thermal response test while drilling (TRTWD) and TRT using heating cables (HC-TRT).

Nonparametric and data-driven interpolation of subsurface soil stratigraphy from limited data using multiple point statistics

An essential task in many geotechnical projects is delineation of subsurface soil stratigraphy from scatter measurements. Geotechnical engineers often use their knowledge on local geology and interpret soil strata boundaries by linear interpolation of measured data. This usual practice may encounter difficulties when interpreting complex deposits, particularly when measurements are limited. In this study, a novel nonparametric, data-driven method based on multiple point statistics (MPS) is proposed to interpolate subsurface soil stratigraphy from sparse measurements. MPS may be formulated as Bayesian supervised machine learning, which adaptively learns high-order spatial information (e.g., curvilinear features of soil layers) using sparse measurements obtained in a specific site and training image that reflects pre-existing engineering knowledge on similar geological settings. The proposed method is the first ever purely data-driven method (i.e., without using any pre-specified parametric functions) for geotechnical site characterization. The proposed method is illustrated by a simulated example and real data from a reclamation site in Hong Kong. The proposed method not only accurately interpolates the subsurface soil stratigraphy from sparse measurements, but also quantifies uncertainty associated with the interpolation. Effects of governing parameters in the proposed method are explicitly investigated, and parameters appropriate for subsurface soil stratigraphy are identified.

The soil moisture regime of charcoal-enriched land use legacy sites

The stratigraphy and properties of soils can be significantly altered by past land use, even in areas that have been continuously used for forestry. An example of such a pedological legacy of past forest use is the soils associated with relict charcoal hearths (RCHs). The physical properties and moisture regime of RCH soils and their ecological implications have hardly been studied, although RCHs are widespread in many forest areas and might be used as model sites to study long-term effects of soil amendment with biochar. The objective of our study was to characterize the soil moisture regime and hydraulic properties of RCH soils through comparison to reference forest soils on sandy substrates in the northeastern German lowlands. RCH and reference soils were studied in woodlands around the historic iron works in Peitz (Brandenburg, Germany), combining laboratory analyses of bulk density, pore size distribution, and saturated hydraulic conductivity with sensor-based monitoring of soil moisture contents and matric potentials. The laboratory analyses reveal a low bulk density and high porosity of the RCH substrates, which is mainly related to larger volumes of coarse and fine pores. Soil moisture monitoring shows higher water contents in RCH soils under relatively wet conditions and lower water contents under dry conditions, as well as strong hysteresis effects, especially after dry periods. The results therefore affirm that the legacies of charcoal production increase spatial and temporal variations in soil moisture, which in turn can cause increased variability in ecological site conditions in charcoal production areas. They furthermore reveal that the high porosity of charcoal-enriched substrates is not necessarily associated with higher water retention and plant-available water contents, and that the pore size distribution and water retention in RCHs differ from those characteristically found for biochar-amended soils.

Seismic response of vertical shafts in multi-layered soil using dynamic and pseudo-static analyses

In this study, numerical analyses were conducted to investigate the load transfer mechanisms and dynamic responses between the vertical shaft and the surrounding soil using a dynamic analysis method and a pseudo-static method (called response displacement method, RDM). Numerical solutions were verified against data from the literature. A series of parametric studies was performed with three different transient motions and various surrounding soils. The results showed that the soil stratigraphy and excitation motions significantly influenced the dynamic behavior of the vertical shaft. Maximum values of the shear force and bending moment occurred near an interface between the soil layers. In addition, deformations and load distributions of the vertical shaft were highly influenced by the amplified seismic waves on the vertical shaft constructed in multi-layered soils. Throughout the comparison results between the dynamic analysis method and the RDM, the results from the dynamic analyses showed good agreement with those from the RDM calculated by a double-cosine method.

Effects of soil-foundation-structure interaction on fundamental frequency and radiation damping ratio of historical masonry building sub-structures

Large-scale simulations and forensic analyses of the seismic behaviour of real case studies are often based on simplified analytical approaches to estimate the reduction in fundamental frequency and the amount of radiation damping induced by dynamic soil-foundation-structure (SFS) interaction. The accuracy of existing closed-form solutions may be limited because they were derived through single degree-of-freedom structural models with shallow rigid foundations placed on a homogeneous, linear elastic half-space. This paper investigates the effectiveness of those formulations in capturing the dynamic out-of-plane response of single load-bearing walls within unreinforced masonry buildings having either a shallow foundation or an underground storey embedded in layered soil. To that aim, analytical predictions based on the replacement oscillator approach are compared to results of two-dimensional dynamic analyses of coupled SFS elastic models under varying geotechnical and structural properties such as the soil stratigraphy, foundation depth and number of building storeys. Regression models and a relative soil-structure stiffness parameter are proposed to quickly predict the frequency reduction induced by SFS interaction, accounting for the presence of an embedded foundation, an underground storey and a layered soil. The effects of SFS interaction are also evaluated in terms of equivalent damping ratio, showing the limitations of simplified approaches. Since the geometric layouts considered in this study are rather recurrent in the Italian and European built heritage, the proposed procedure can be extended to similar structural configurations.

Modal analysis of Rayleigh waves using classical MASW-MAM approach: Site investigation in a reclaimed land

Surface wave tests such as the multi-channel analysis of surface waves (MASW) and microtremor array measurements (MAM) offer a fast and convenient way of measuring the shear wave velocity (Vs) of the ground for geotechnical site investigation due to their non-intrusive nature. However, it has been widely reported that the accuracy and resolution of the Vs profile depend on the construction of the dispersion image and its interpretation. While many advanced computational techniques have been proposed to process surface waves into a final Vs profile, we opted for the classical ‘picking and inverting’ approach in the current study. This is in view of the lower required computation power as well as the relatively uniform geology of the site. Surface wave tests (MASW, MAM and horizontal-to-vertical spectral ratio) were carried out at a remote reclaimed land in Singapore. A systematic methodology for the modal analysis of Rayleigh waves based on combined MASW and MAM tests is presented. The MAM dispersion image was constructed using the phase shift method, the extended spatial autocorrelation (ESAC), and the refraction microtremor (ReMi) method but a meaningful dispersion curve could only be obtained using the phase shift. Due to the modes of energy in the low frequency regime being unclear in the dispersion image, an idealized synthetic model of the site was set up to guide the mode identification process. The combined dispersion curve and HVSR profile were jointly inverted to construct the final Vs profile, which agreed quite well with the seismic cross-hole tomography experiments and bore-log information. It is also demonstrated that the inversion of the fundamental mode alone led to slight errors and low resolution in the final velocity profile, even for such a simple soil stratigraphy.

Analysis of buried steel pipelines at watercourse crossings under liquefaction-induced lateral spreading

At watercourse crossings, buried steel pipelines typically transition from a shallow burial depth to a depth below the maximum scour depth of the watercourse channel. This paper investigates the pipeline response when such watercourse crossings undergo liquefaction-induced lateral spreading. The investigation is performed via non-linear finite element analyses (FEA) for a multitude of “generic” combinations of watercourse depth, liquefiable soil stratigraphy and pipe characteristics. The FEA provide peak pipeline strains and are used to define allowable peak permanent ground displacement (PGD) values for each “generic” case. It is shown that pipe strain is most intense at pipe overbends and that the allowable peak PGD increases with the depth of the watercourse, as there is less interaction between the strained overbend and the sagbend areas. Furthermore, allowable peak PGD increases slightly with pipe diameter and significantly with pipe wall thickness, while it reduces with soil friction and the inclination angle of the downward pipeline transition below the waterbed.

The regenerative building: A concept of total sustainability

The concept of building’s sustainability is progressively evolving, from the mere issues of limiting the energy needs of the building, extends to include new areas. The long-term sustainability visions (in Switzerland the “2000 W Society” by year 2100) imply not only technological changes but above all radical changes in the human behaviour. A multidisciplinary study, carried out by SUPSI and specialists, proposes a method for determining the parameters for the design of a building by year 2100. It also shows that in order to achieve long-term sustainability goals (primary energy reduction and CO2 emissions per capita, 2000 W and max 1 ton CO2), alimentation can be considered as a building need. The high potential in reducing primary energy needs in this area makes possible to compensate others energy consumptions and CO2 emissions of the building inhabitants and of the building itself. The sustainable building of the future shall therefore: - present a zero or compensated operating energy need; - present minimal energy need for construction; - allow food production (Urban Farming, Building Integrated Agriculture) through natural and regenerative agriculture (self-production); - promote and act as a shelter for local flora and fauna (regenerative); - respect the soil stratigraphy (reversible).

Simulating realistic geological stratigraphy using direction-dependent coupled Markov chain model

The design of geotechnical structures depends significantly on soil stratigraphy. The determination of geological stratigraphy is generally based on site investigations such as drilling, standard penetration tests and cone penetration tests. When the in-situ tests or boreholes are limited, the characterization of complex strata is difficult. The objective of this study is to develop an improved coupled Markov chain model (CMC) to simulate complex geological stratigraphy based only on limited in-situ data. The traditional CMC model is improved by developing a direction-dependent CMC method to address the strong variation of soil properties among boreholes. The difficulty in simulating different dip directions and prisms in a geological profile is solved by developing proper simulation direction in the modelling. The stratigraphy at a construction site in Hong Kong is characterized using the proposed method. It is found that both upwards and downwards inclined interfaces can be simulated very well. The prisms within a soil layer can be predicted. The accuracy of the method is closely related to the locations of the existing boreholes. The influence distance of a borehole is approximately 14 m.

Modelling and comparing 3-D soil stratigraphy using subsurface borings and cone penetrometer tests in coastal Louisiana, USA

ABSTRACTComplex subsurface geology of coastal Louisiana, formed under fluvial, deltaic, and sea level influences, increases the uncertainty in design and construction of hard and natural infrastructure. In this study, twenty-four (24) collocated soil borings and CPTs at the Inner Harbor Navigation Canal (IHNC) in New Orleans, Louisiana were used to construct multiple three-dimensional (3-D) soil stratigraphy models by ordinary kriging. To explore the spatial distribution of soils at the site, four soil stratigraphy models were established, including the unified soil classification system (USCS) from borings and three constructed using soil behaviour type (SBT) correlations. The SBT correlation using friction ratio () and corrected cone resistance () was found to better represent organic soils pervasive in coastal Louisiana compared using normalised friction ratio with normalised cone resistance, and using soil classification boundary. The comparison shows that the normalisation of sleeve resistance translates the data to higher normalised friction ratio compared to values. The boring and CPTu sounding comparisons suggest that extending the from 8% to 20% in the Rf–qt chart to better capture the organic-rich soils in coastal Louisiana.

Public health effects due to insufficient groundwater quality monitoring in Igando and Agbowo regions in Nigeria: A review

This paper emphasizes the need for monitoring groundwater resources by analyzing the health implications of inadequate monitoring. It highlights the importance of groundwater quality monitoring in Nigeria—a country where population dependence on groundwater is 60%. The effects of Soluos dumpsite leachate in Igando, Lagos–Nigeria, and septic tank seepages in Agbowo, Ibadan–Nigeria on groundwater quality are analyzed. All samples used in this study appeared to be microbially contaminated. This is linked to too close distances [< 50 ft (15.24 m) the United States Environmental Protection Agency recommendation] between septic tanks and groundwater wells, as well as non-engineered dumpsites used for waste disposal. This shows that groundwater within the study area is unsafe for drinking purposes. Even with the clayey soil stratigraphy of the study area which is believed to influence the natural attenuation of leachate into groundwater, high concentrations of lead (Pb) and manganese (Mn) were seen in some locations around the dumpsite. The study points to the inherent cost for individuals and government due to insufficient groundwater quality which could have been otherwise avoided through groundwater monitoring and proper waste management. This review accentuates the need for improved water quality towards achieving SDG 6.1 (universal and equitable access to safe drinking water) and SDG 3 (Good health and well-being) in Nigeria.