Marine Clay Research Articles

Effects of frequencies on the cyclic behavior of marine soft clay under different consolidated stress paths

To experimentally investigate the effect of frequency on the cyclic behavior of marine soft clay under different consolidated stress paths, a series of cyclic tests on remolded Wenzhou marine clay were conducted under undrained conditions covering various frequencies and consolidated stress paths using a triaxial apparatus. The development of pore water pressure, stress–strain relationship, and resilient modulus was analyzed. Several useful conclusions were reached from this study. First, the trends of pore water pressure development can be divided into three stages: linearly increasing, slowly increasing, and stable. Second, the frequency has a more pronounced influence on the number of cycles of the steady value of pore water pressure than the counterparts of values of the ratio of the radial to vertical consolidation stresses, K. Then, a unified linear equation was established based on the consideration of different K values on a logarithmic scale. Finally, the shapes of the stress–resilient strain hysteretic loops and the range encompassed by the stress–resilient strain hysteretic loops are slight as the value of K decreases, which indicates that the K value has a slight effect on the shift in the type of elastic behavior of clay.

An approach for characterising electrical conductivity of cement-admixed clays

This paper proposes a framework for relating electrical conductivity of cement-treated marine clay to its strength. The feasibility of relating conductivity to strength is first examined by measuring the two quantities over a range of water-cement and soil-cement ratios as well as curing periods. The results indicate that, within a limited curing period, conductivity changes are sufficiently monotonic to permit its correlation to strength. This leads to the proposal of two empirical relationships, which relate the strength and conductivity to the water-cement and soil-cement ratios of the treated soil. By assuming that there is no diffusion of water from the binder during the relatively short mixing duration, the water-cement and soil-cement ratios can be related to the in-situ water content, water-cement ratio of the binder and the binder mass fraction. If the first two quantities are constant over the site and only the last quantity is a variable, then the conductivity can be uniquely related to the strength. This provides the framework for correlating strength and conductivity measurements, which would allow electrical resistivity measurements to be used to infill point strength data from core samples for quality control of cement-treatment works.

Evaluation of stress history and undrained shear strength of three marine clays using semi-empirical methods based on Piezocone Test

The paper presents a comparative study between semi-empirical methods for the estimation of pre-consolidation pressure and undrained shear strength from Piezocone (CPTu) data. The first method, proposed by Massad, was developed from observing the variation of these parameters with depth; the second method, proposed by Mayne, was developed from simplifications and relationships between the Spherical Cavity Expansion Theory (SCET) and the Critical State Theory; the third method was proposed by Mayne, which considers the variations due to soil type from the CPT Index to estimate the pre-consolidation pressure. The methods were validated based on their applications to the marine clay from Santos Coastal Plain, Brazil, Bothkennar clay from Scotland, and Torp Clay from Sweden. It is intended to verify if the results are consistent with each other, with the stress history of these soils and with the available test results. The application of the Massad’s method led to results close to the available reference values. The results of the Mayne’s method based on SCET showed great variability in behavior comparing to the test data depending on the case study. By the Mayne’s method based on CPT Index values, the calculated pre-consolidation pressures were slightly higher than the values of the available test data. The variations in the results highlighted the importance of validating estimates based on semi-empirical methods through specific tests and the knowledge of geological history contributes to predicting the behavior of clays, since they showed good agreement with the available data from oedometer tests.

State parameter governing the mechanical properties of cement-treated clays

A new state parameter that is capable of characterizing the mechanical properties of cement-treated clays with different mixing proportions, curing time, and stress conditions is developed in this study. The development is conducted by combining the effect of stress level based on the critical state theory with the effective void ratio. Based on the experimental data of cement-treated Bangkok clay performed in this study together with those of cement-treated Singapore marine and Ariake clays reported in previous studies, the analyses reveal that the state parameter is proven to be an efficient parameter for characterizing the mechanical properties of cement-treated clays with different base clays under various mixing proportions and curing times tested under various stress conditions. Furthermore, empirical equations to assist the establishment of the effective void ratio on the critical state locus from the plastic limit value of the base clay are suggested based on regression analyses. The state parameter can thus be computed and the engineers can preliminarily estimate the mechanical properties of cement-treated clay in the planning stage.

Characterization of Ancient Burial Pottery of Ban Muang Bua Archaeological Site (Northeastern Thailand) Using X-ray Spectroscopies

Ancient potteries found at Ban Muang Bua, located in northeastern Thailand, associate with Thung Kula Ronghai culture. Most of them are products used in daily life and grave goods. The potsherds were examined using techniques based on X-ray spectroscopy. Elemental composition and morphology were analyzed using proton-induced X-ray emission spectroscopy (PIXE) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS). Three-dimensional analysis was performed using X-ray tomographic microscopy based on synchrotron radiation (SR XTM). Irregular plate-like particles of composites with a wide range of size distribution were found in the potsherds. The major (O, Si, and Al), minor (C, Fe, Ca, and K), and trace elements (P, S, Ti, Na, Mg, and Zn) which were observed can provide the information about raw materials and production of pottery. The 3D tomographic images show the internal feature of these samples. The combination of SEM-EDS, PIXE, and SR XTM is a powerful tool for archaeological research especially in terms of composition and internal structure. The results imply that the raw materials of pottery were sandy soil derived from marine sands, clays, and salt deposits that were mostly iron-rich-kaolin clay. The production was carried out with low firing temperatures (~600–900 °C) in open-air kilns.

Relationship between the initial water content of clay and the mixing quality of cement treated marine clay

Relationship between the initial water content of clay and the mixing quality of cement treated marine clay

Utilization of pelagic clay to prepare porous silicon as negative electrode for lithium-ion batteries

In order to rationally develop abundant marine clay resources, in view of its large specific surface area, looseness, high porosity, poor crystallinity, and high activity, the magnesium thermal reduction method was used to reduce Si4+ in the pelagic clay minerals to obtain porous silicon. Through targeted process design and reaction condition control, the obtained silicon material not only has higher crystallinity, but also has layered accumulation pores with relatively uniform pore size distribution. It had a BET specific surface area of 81.473 m2·g−1, a pore volume of 0.290 cm3·g−1, and an average pore size of 10.193 nm. In addition, using sucrose as the carbon source, the prepared silicon was modified to obtain a carbon-coated porous silicon material, whose performance as lithium-ion battery negative electrode was preliminarily characterized. The specific capacity, cycling performance and multiplicity performance test results showed that the porous silicon derived from pelagic clay exhibits good cycling and rate performance under the carbon coating conditions, which means that it had a certain potential in the field of lithium-ion batteries. This work opened up a new way for high value-added utilization of pelagic clay.

Numerical study on the suction force of jack-up mat foundation on marine clay seabed

A deep layer of soft clay is widely present on the seabed in the offshore area of China. The traditional jack-up spudcan faces the problem of difficult insertion and extraction in clay seabed. Jack-up mat foundation is more suitable in soft clay than spudcan for its lower requirements on bearing capacity. Due to the poor permeability of clay, the uplifting process of the mat foundation needs to overcome a large soil suction force. In this study, three-dimensional numerical model is established to investigate the suction force of jack-up mat foundation on marine clay seabed. The elastoplastic constitutive model, which can describe the structural and over-consolidation of soft marine clay seabed, was embedded in commercial software ABAQUS through UMAT subroutine. The cohesive contact model was adopted to stimulate the interaction between mat foundation and the seabed soil. Field test was conducted to verify the accuracy of the numerical model. Then, the effects of degree of over-consolidation, degree of structural, depth of clay, interface stiffness and eccentric uplift loading on suction force are studied in detail. Numerical results show that the effects of degree of over-consolidation and structural of soil have significant influence on the suction force. The suction force first increases rapidly and then decrease gradually as the thickness of the upper dimensionless clay layer increases. With the increase of the uplift eccentricity, the suction force reduces continuously.

Liquid limit of marine soft clay encountering desalination percolation process

The diffuse double layer (DDL) theory indicated that the liquid limit (LL) of clays decreases based on pore-water salinity during salinization tests conducted in a laboratory. However, LL also decreased based on pore-water salinity when authors conducted geological investigations in the regression depositional zone in Lianyungang city, contradicting the DDL theory. This contradictory finding is inferred due to the coupled effect of salinity leaching and erosion of the colloid during a desalination percolation process. To confirm this hypothesis, 3 model tests of distilled water percolation and seven accelerated percolation tests were designed in this study, and the soil/water characteristics after desalination percolation were determined. The results reveal that the pore-water salinity leaches are combined with the colloidal erosion during the desalination percolation process, leading to the gradual decrease in LL based on the reduction of salinity and suggesting that the dominant effect is the colloidal erosion. At the initial stage of the desalination process, the colloids easily erode from the clay matrix due to the weakened salinity inhibition on the colloid release, leading to the seepage channel expansion, and hence the increase in colloid dimension and concentration in leachates throughout percolation. Based on the further decrease in pore-water salinity, the colloids in the clay matrix continuously release and inversely clog the inner channels of the soils, decreasing the colloid dimension and concentration in leachates. When the percolation process is sufficiently long, all salinity would be leached out from the clay matrix, and only the erosion of the colloid would be identified.

Damping of a soft marine clay subjected to the combination of monotonic and cyclic shear stresses

In relation to the dynamic behavior of soils, the damping (D) and the dynamic shear modulus (G) has always acquired special relevance, since its evaluation has allowed the application of simplified models of dynamic soil behavior. They depend on many factors, being necessary to include the combination of monotonic (τo) and cyclical shear stress (τc) that are inevitably present under any structure. As part of an extensive testing programme, the objective of the present paper, besides the identification and classification tests, was to perform 139 simple cyclic shear tests with different levels of static stresses (τo) before the cyclic phase. This paper refers to the influence that the combination of monotonic (τo) and cyclic shear (τc) stresses has on the damping of a soft cohesive soil susceptible to sudden failure. Laboratory tests were carried out on undisturbed samples from the Port of Barcelona, in Spain. The samples were obtained at depths between 29 m and 52 m, that correspond to an effective vertical stress of (σ′ov) between 277 kPa and 413 kPa, respectively. In general, the results indicate that: a) the combination of τo and τc controls the damping ratio (D), b) in the combined monotonic and cyclic case, it is possible to establish empirical functions of the type D = D(N, γc), D = D(N, G/σ′ov) and D = D(N, u/σ′ov), for different (τo/σ′ov) ratios and c) it is possible propose a chart to evaluate the damping ratio as a function of N, G/σ′ov and u/σ′ov, for different (τo/σ′ov) ratios.

Busan Geoje Fixed Link

The Busan Geoje Fixed Link project is one of the landmark projects in South Korea, providing a road connection between Gaduk and Geoje Island near to the city of Busan at the Southern tip of the Korean peninsula. The project consists of two Cable Stayed Bridges, an Immersed Tunnel, rock tunnels and it has a total length is over 8 km.This paper will focus on the immersed tunnel part of the link and the particular challenges that the project faced in designing and constructing the tunnel, these challenges required a significant evaluation in immersed tunnel technology. The tunnel consists of 18 tunnel elements and has a total length of 3.6 km. The tunnel location was characterised by the following conditions:•a large depth, maximum depth of the tunnel is 48 m below sea level.•the tunnel is located in a seismic sensitive area.•the tunnel is founded largely on weak marine clay, but parts also on bedrock.•part of the tunnel was constructed on a sub sea embankment which is also founded on a weak marine clay.•the tunnel has been constructed in a location that is facing to the Sea of japan and is exposed to a severe wind and wave environment with large long period swell waves present for part of the year.Because for only a few months a year the wave- and weather circumstances were suitable for immersion, extensive numerical and physical model tests were carried out to predict the behaviour of the immersion system for the expected conditions. These model tests were used to determine the wind and wave climate that the immersion system could cope and a go, no-go range of conditions.Additionally, an accurate, sophisticated short and long term wave and weather forecast system was developed. This system enabled forecasts to be made within a 10 cm wave height accuracy, for periods leading up to the element transport and immersion operations which allowed the immersion operations to be possible within acceptable risks.The tunnel elements (TE) were built in batches in a pre-cast yard (PC). After inundation of the dock the elements were transported to a mooring location close to the PC-yard for fitting out and to wait for favourable immersion weather.The elements were immersed using two catamaran pontoons and placed in a previous dredged trench on the sea bed. A taut mooring configuration was used in order to reduce the wave influenced motions to a minimum. Anchor points were created by pre-installed plate anchors.Due to the total length and installation depth of the tunnel the traditional survey systems using towers and total stations were not suitable. Therefore new survey methods were developed, these included a tautwire system and an Ultra Short Base Line (USBL) acoustic system were used for the positioning of the elements during the immersion operation. Fine positioning of the TE’s under swell wave influence was done using a special designed External Positioning System (EPS) and placed on the pre-laid screeded gravel bed.

Undrained Deformation Characteristics of Soft Marine Clay Subjected to One-Way Cyclic Loading with Variable Confining Pressure

To gain a better understanding of the undrained deformation characteristic of saturated marine clay soil subjected to vehicle cyclic traffic load, a sophisticated dynamic triaxial was used to conduct a variety of undrained one-way compression cyclic experiments with variable confining pressure (VCP) as well as constant confining pressure (CCP). The results indicate that, compared to CCP test results, VCP is helpful to raise the axial resilient modulus (Mr) and restrain the permanent plastic strain ( ε a p ) development of the specimens. By normalization analysis of the measured data of Mr and ε a p , the virtually unique correlation between normalized average resilient modulus, normalized permanent axial strain after 1,000 loading cycles, and normalized mean normal stress is established, respectively, regardless of the values of CSR. Additionally, the VCP influence on ε a p is quantified and fitted by a power law function, which can be used for subsoil deformation prediction and provides new insights into the mechanics of strain accumulation under undrained cyclic loading conditions.

A study on marine clay as fine aggregate in microbial cement mortar mix

The scarcity of natural resources like river sand pushes construction industries in search of alternative materials to replace fine aggregate in building construction. While working with such replacement materials, few drawbacks in mechanical properties is observed. In this study, marine clay was used as fine aggregate along with microorganism (Bacillus. Subtilis MTCC441) to improve the mechanical properties of the mix. It was observed that a significant improvement in compressive strength and reduction in water absorption for microbial marine clay mortar mix compared to the control mix. The microbial excavated soil mixes could not show crack healing properties by bioprecipitation of calcium carbonate crystals. An induced crack of width 0.5 mm could not be healed when observed for 60 days with one-week intervals.

Three (3D) dimension model of settlement differences of the clay ground under rigid foundation by the affection of the groundwater variations – A comparison

In recent decades, settlement differences of the Clay ground implemented in areas and countries in the world. Whereas marine clay ground behaviors under Rigid foundation to build the construction on the clay ground with marine clay origin was evaluated the different methods such as Field and experimental measuring method, Finite Element method, formulas or TERZAGHI method and so on. Moreover, the influence of the groundwater levels is one of the most quite important problems to be needed considering. The object of this paper uses Standard Penetration (SPT), Unconfined Compression Test, and TERZAGHI formula, groundwater effects, and simulation by the software for measuring the vertical displacement (or settlement differences) of the rigid foundation on marine clay origin ground at Vinh Quang ward, Rach Gia town, Viet Nam. Results of the paper described clearly for settlement differences (vertical displacement) of the Rigid foundation as building loading with a comparison between Field, experimental, and software simulation so it can consult effectively for design and doing construction works in Civil and Geology Engineering.

Semianalytical Solution for Thermal Consolidation of Viscoelastic Marine Clay with the Fractional Order Derivative

The deformation property of marine clay under a heat source has received considerable attention in the geotechnical literature. In this paper, a three‐parameter fractional order derivative model is introduced into the thermo‐hydro‐mechanical coupling governing equations with thermal filtration and thermo‐osmosis to simulate viscoelastic characteristics of marine clay. The excess pore pressure, temperature increment, and displacement of marine clay are derived by using the Laplace transform method, and the semianalytical solution for the one‐dimensional thermal consolidation in the time domain is derived by using a numerical inversion of the inverse Laplace transform. The influence of the order of the fractional derivative, material parameters, and phenomenological coefficient on thermal consolidation is investigated based on the present solutions. It is shown that the influence of the fractional derivative parameter on the excess pore pressure and displacement of marine clay depends on the properties of soil mass, and the temperature increment has an obvious effect on the thermal filtration and thermo‐osmosis process.

A study on soil interface interaction

Interfaces between soil-concrete, soil-steel, soil-root, soil-wood, soil-polymer frequently stumble upon various geotechnical engineering applications. Several studies agree that the material properties interfacing with the soil, the properties and the performance of the soil at the interface makes it even more multifaceted and interesting. Highly plastic, over consolidated clays, crushable calcareous sands, soft marine clays, clays with organic content etc., show unusual complications related to cast in situ and driven pile shaft capacity calculations, functioning of various infrastructural projects that comes in contact with soil. Several testing methodologies have been developed to examine the interface behaviour under different conditions, it substantiates determination of the interface shear strength parameters for design. Such studies involve real time understanding of the frictional anisotropy which is possible through large scale direct shear tests, tilting frames, simple shear tests and radial shear experiments for finding the interface between soil and material. In addition, microstructural investigations are also to be piloted to realize the shearing mechanism of the soil material interfaces. Yet standard testing conditions for evaluating the interface angle simulating the real time environment is not yet available. A systematic review of the study on appropriate mechanisms available for investigating the Soil Material Interface is done, which will aim to suggest improvements by critically identifying their shortcomings.

Multiple Thixotropisms of Liquid Limit–Consistency Clays Unraveled by Multiscale Experimentation

AbstractMultiscale experiments were conducted to investigate the thixotropic behavior of a naturally occurring illite-rich marine clay with a moderate salinity and of a manufactured, highly purifie...

Experimental Study on Working Property and Strength Behavior of Waste Marine Clay with High Water Content Modified by Quicklime, Grounded Calcium Carbonate and Wxs-Ii Soil Stabilizer

Experimental Study on Working Property and Strength Behavior of Waste Marine Clay with High Water Content Modified by Quicklime, Grounded Calcium Carbonate and Wxs-Ii Soil Stabilizer

Determination of Consolidation Parameters of Geomaterials Using Modified CRS Consolidation Testing System

Nowadays, the constant rate of strain (CRS) consolidation phenomenon has gained more attention as an alternate testing method to evaluate the consolidation characteristics of finegrained soils based on strain rate criterion. In the present study, a modified consolidation cell has been fabricated indigenously and carried out a series of CRS tests using a conventional triaxial loading frame at four different strain rates on reconstituted samples of marine clay at 0.002, 0.003, 0.004 and 0.005 mm/min, black cotton soil at 0.0025, 0.003, 0.005 and 0.0075 mm/min, red mud at 0.10, 0.125, 0.25 and 0.50 mm/min, and Varanasi local soil at 0.05, 0.075, 0.10 and 0.125 mm/min. Based on the pore pressure ratio (PPR) criterion, the best suitable strain rates for marine clay, black cotton soil, red mud, and Varanasi local soil were found to be 0.002, 0.0025, 0.1 and 0.05 mm/min, respectively. Further, the consolidation parameters namely primary compression index (cc), recompression index (cr), coefficient of consolidation (cv), coefficient of axial compressibility (av) and permeability (k) obtained through proposed CRS consolidation method are compared and validated successfully with the parameters obtained through Incremental Loading (IL) tests using both conventional and modified oedometer cells.

Impact of environmental acidity on the geomechanical and mineralogical behavior of marine clay

Impact of environmental acidity on the geomechanical and mineralogical behavior of marine clay