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The one-dimensional consolidation analysis of clays considering creep compression is a classical issue in soil mechanics and geotechnical design. The major debate lies in how to predict the consolidation settlement for a thick layer in the field using parameters obtained from a thin specimen from the laboratory. Different hypotheses have been advocated, based on which various methods and constitutive models have been developed. However, there are still some questions unaddressed and concepts inconsistently used, which may mislead engineers in the selection of methods/models and may result in settlements underestimated on a risk design side. In this paper, a state-of-the-art review and a thorough comparison study are performed on the existing methods and models for the consolidation analysis of clays exhibiting creep, from theoretical derivations to numerical simulations in comparison with soil test data. An in-depth discussion is carried out on several key issues related to the thickness effects on the time-dependent compression behaviour of clays. The arguments of Hypothesis A and Hypothesis B are revisited based on the current development of constitutive theories. Three existing elastic visco-plastic (EVP) models that consider the creep compression implicitly during the whole consolidation process can perform well in predicting the settlement of clay layers with different thicknesses, and are in line with Hypothesis B. It is concluded that using existing EVP models based on porous-media continuum mechanics is a rigorous scientific method (also called "rigorous" Hypothesis B method), which is superior to the old Hypothesis A method which has logic errors and may result in unsafe underestimation of settlements. [ABSTRACT FROM AUTHOR]

This paper presents a consolidation model for stone column-reinforced soft ground subjected to time-dependent loading under free strain condition. Smear effects and three types of loadings, namely, constant loading, ramp loading, and sinusoidal loading, are considered in the developed consolidation model, which is solved by a numerical method based on a partial differential equation solver. The applicability of the proposed consolidation model and the reliability of the numerical method are demonstrated and verified by well-predicting the consolidation behaviors of two practical engineering cases and one laboratory experiment. The verified model and the numerical method are then employed to investigate the effects of smear zone and time-dependent loading on consolidation characteristics of stone column-improved soft ground. The results indicate that the excess pore water pressure undergoes a sharp change at the interface between the smear zone and the undisturbed zone due to smear effects. The smaller the range of the smear zone, the faster the settlement of the composite foundation develops. The faster the loading rate, the faster the dissipation of excess pore water pressure and the faster the settlement develops. In addition, for the foundation subjected to sinusoidal loading, the higher loading frequency results in a larger amplitude corresponding to the excess pore water pressure and a smaller amplitude corresponding to the settlement of the soil. [ABSTRACT FROM AUTHOR]

Many design guidelines have been proposed for piled embankments, most of which consider piles or columns as rigid inclusions. In this study, a small-scale physical model test was performed to investigate the load transfer mechanism of a geotextile-reinforced sand layer over a soft subsoil improved by semirigid columns. A multi-stage load was applied at the top of the sand layer until the columns started to yield. When the columns yielded, a reverse load transfer was observed. Vertical stresses were measured and analyzed in terms of efficacy and stress reduction ratio (SRR) with a comparison of existing design guidelines for assessing soil arching. Among the reviewed guidelines, the approach recommended by the Dutch guidelines provided the closest results to the experimental data, whereas the one adopted by the American guidelines predicted well the change in efficacy and SRR under different surcharge loads. However, the load transfer mechanism after the yielding of columns is beyond the scope of the existing design guidelines. In addition, it was found through regression analysis that the increment of vertical stresses on columns and surrounding soil followed an inclined line under partially undrained conditions during loading stages and a curve during consolidation. [ABSTRACT FROM AUTHOR]

Spatial variability of engineering properties caused by the natural characteristic heterogeneity is a common feature in soil layers. Meanwhile, changes in soil properties during consolidation and large strains are commonly encountered during long-term consolidation analysis of soft soils; however, few studies have considered these factors. A 1-D consolidation model fully coupled with elastic viscoplastic constitutive model, called EVPC, is developed using piecewise-linear method for long-term settlement of soft clay. The EVPC incorporates the idea of 'equivalent time' to account for large strain, soil self-weight, compressibility and permeability with spatial variability and high nonlinearity, as well as creep during the consolidation process. A comparison with finite element simulations and oedometer tests with different thicknesses of soil layer under multi-stage constant loads verified the effectiveness and accuracy of the EVPC's deterministic analysis. After that, the long-term settlement and excess pore pressure distribution of Berthierville clay layer from the field test are estimated using EVPC probabilistic analysis. All measurements from the field test are within the range of corresponded closely to the high probability density results of the probabilistic analysis, and the excess pore pressure is revealed to be more sensitive to the spatial variability of soil parameters than settlement. [ABSTRACT FROM AUTHOR]

How to predict the long-term deformation of natural soft soils under embankments has been an important yet challenging issue in geotechnical and transportation engineering. The major difficulties lie in consolidation analyses of thick soil layers, modelling of the nonlinear time-dependent stress–strain behaviour of clayey soils, and proper determination of soil parameters. While finite element (FE) software has great advantages and wide applications in consolidation analyses, development of reliable simple methods, which can be conveniently used by engineers, is also needed. In this paper, both a fully coupled FE model and a simplified Hypothesis B method are developed and applied for long-term deformation analyses of two test embankments on the multi-layered Malaysian marine clays. FE simulations are conducted using PLAXIS with a nonlinear 3-D elastic visco-plastic (3-D EVP) model. A series of parametric studies are carried out on the influences of soil parameters and modelling techniques using this FE model. A simplified Hypothesis B method with the nonlinear 1-D EVP model and modifications for 2-D stress diffusion and buoyancy effects is derived and applied for estimating the long-term consolidation settlement curves of the two test embankments. It is found that the fully coupled FE model with the nonlinear 3-D EVP can simulate the long-term embankment displacements with good agreement with measured data. Parametric studies indicate that using averaged soil indices and updating static pore pressure have significant contributions to the accuracy of simulations. The settlements calculated by the improved simplified Hypothesis B method are found in close agreement with FE simulation results and measured data. [ABSTRACT FROM AUTHOR]

Consolidation of marine soft soils with prefabricated vertical drains (PVDs) and vacuum preloading is a hot spot of research in marine geotechnical engineering. Marine soft soils usually have low permeability and the consolidation is time-consuming. To accelerate the consolidation of marine soft soils, elevating the temperature with heating-aided PVDs in soils has been an attractive option. In this study, a series of laboratory tests were conducted to investigate the influence of heating on Hong Kong marine deposits (HKMD). Through the oedometer tests, the effects of heating on the compression and consolidation behavior are quantified. In the two physical model tests with vacuum preloading, it is indicated that increasing the temperature to 40 °C in HKMD can significantly speed up the consolidation process, reduce vacuum loss and increase the settlements and effective stress in a shorter period. To reveal the mechanism of thermal effect on HKMD, the molecular dynamics simulation was performed with three typical mineral elements, and the thermal effect on the different responses of minerals in HKMD is interpreted. Furthermore, theoretical analysis with Hansbo's theory and simplified Hypothesis B method is also conducted for calculating the consolidation settlements of the model tests, with a quantified smear factor accounting for the combined effects of non-uniform consolidation, clogging, and temperature during vacuum-heat preloading. [ABSTRACT FROM AUTHOR]

A large amount of bentonite slurry is dumped as construction waste in fill banks around the world. In order to reuse them, it is important to determine the mechanical and hydraulic parameters of bentonite-soil mixtures containing different montmorillonite contents. The establishment of these parameters with index properties is an efficient and simple way. Despite the proposal of some correlations to estimate the compression and swelling indices for kaolinite or illite-dominated soils (KIDSs) with relatively low liquid limits, they are unsuitable for bentonite-soil mixtures dominated by montmorillonite. Besides, no correlation was given for predicting the parameters in the non-linear creep function as well. In this study, the results of the Atterberg limits, oedometer, and scanning electron microscope (SEM) tests on five mixtures with different montmorillonite contents from 5 to 35% were presented. Compression and swelling indices creep coefficient as well as the non-linear creep parameters and hydraulic conductivity of bentonite-soil mixtures were obtained. Several correlations were put forward to estimate the mechanical parameters with Atterberg limit indices. The proposed correlations were further verified using the data collected from literature, which can well estimate the mechanical parameters of soils with a liquid limit of above 50%. In addition, a simplified model with a homogenization approach was developed to estimate hydraulic conductivity with reasonable accuracy, which is easier to be adopted in practical engineering. [ABSTRACT FROM AUTHOR]

It is well known that the calculation of consolidation settlements of clayey soils shall consider creep compression in both "primary" consolidation and so-called secondary consolidation periods. Rigorous Hypothesis B method is a coupled method and can consider creep compression in the two periods. But this method needs to solve a set of nonlinear partial differential equations with a proper elastic viscoplastic (EVP) constitutive model so that this method is not easy to be used by engineers. Recently, Yin and his coworkers have proposed a simplified Hypothesis B method for single and two layers of soils. But this method cannot consider complicated loadings such as loading, unloading and reloading. This paper proposes and verifies a general simple method with a new logarithmic function for calculating consolidation settlements of viscous clayey soils without or with vertical drains under staged loadings such as loading, unloading and reloading. This new logarithmic function is suitable to cases of zero or very small initial effective stress. Equations of this simple method are derived for complicated loading conditions. This method is then used to calculate consolidation settlements of clayey soils in three typical cases: Case 1 is a single soil layer without vertical drains under loading only; Case 2 is a two-layered soil profile with vertical drains subjected to loading, unloading and reloading; and Case 3 is a real case of a test embankment on seabed of four soil layers installed with vertical drains under three stages of loading. Settlements of all three cases using the new general simple methods are compared with values calculated using rigorous fully coupled finite element method (FEM) with an elastic viscoplastic (EVP) constitutive model (Cases 1 and 2) and measured data for Case 3. It is found that the calculated settlements are in good agreement with values from FEM and/or measured data. It is concluded that the general simple method is suitable for calculating consolidation settlements of layered viscous clayey soils without or with vertical drains under complicated loading conditions with good accuracy and also easy to use by engineers using spreadsheet calculation. [ABSTRACT FROM AUTHOR]

The Turán number of a graph G, denoted by ex(n, G), is the maximum number of edges of an n-vertex simple graph having no G as a subgraph. Let S ℓ denote the star with ℓ + 1 vertices, and let ⋃ i = 1 k S ℓ i denote the disjoint union of S ℓ 1 , … , S ℓ k . For k ≥ 2 and ℓ 1 ≥ ⋯ ≥ ℓ k ≥ 1 , Lidický et al. [On the Turán number of forests, Electron. J. Combin., 20(2)(2013)#P62] proved that e x (n , ⋃ i = 1 k S ℓ i) = max 1 ≤ i ≤ k { ⌊ (ℓ i + 2 i - 3) n - (i - 1) (ℓ i + i - 1) 2 ⌋ } for n sufficiently large. In this paper, we further show that e x (n , ⋃ i = 1 k S ℓ i) = max 1 ≤ i ≤ k (ℓ i + 2 i - 3) n - (i - 1) (ℓ i + i - 1) 2 for n ≥ N k by giving another proof, where L j = max 1 ≤ i ≤ j { ℓ i + 2 i - 3 } for 2 ≤ j ≤ k and N k = max 2 ≤ j ≤ k (∑ i = 1 j - 1 ℓ i + 1) (∑ i = 1 j 2 ℓ i - ℓ j + 2 j - 5) + (j - 1) ℓ 2 - (j - 2) ℓ j + j 2 - 3 j + 5 L j - ℓ j - 2 j + 5 . [ABSTRACT FROM AUTHOR]

A nonincreasing sequence π = (d1,..., dn) of nonnegative integers is a graphic sequence if it is realizable by a simple graph G on n vertices. In this case, G is referred to as a realization of π. Given two graphs G1 and G2, A. Busch et al. (2014) introduced the potential-Ramsey number of G1 and G2, denoted by rpot(G1, G2), as the smallest nonnegative integer m such that for every m-term graphic sequence π, there is a realization G of π with G1 ⊆ G or with G 2 ⊆ G ¯ , where G ¯ is the complement of G. For t ≽ 2 and 0 ⩽ k ⩽ ⌊ t 2 ⌋ , let Kt−k be the graph obtained from Kt by deleting k independent edges. We determine rpot (Kn, Kt−k) for t ⩾ 3 , 1 ⩽ k ⩽ ⌊ t 2 ⌋ and n ⩾ ⌈ 2 k ⌉ , which gives the complete solution to a result in J. Z. Du, J. H. Yin (2021). [ABSTRACT FROM AUTHOR]

High-throughput single-cell RNA sequencing (scRNA-seq) is a popular method, but it is accompanied by doublet rate problems that disturb the downstream analysis. Several computational approaches have been developed to detect doublets. However, most of these methods may yield satisfactory performance in some datasets but lack stability in others; thus, it is difficult to regard a single method as the gold standard which can be applied to all types of scenarios. It is a difficult and time-consuming task for researchers to choose the most appropriate software. We here propose Chord which implements a machine learning algorithm that integrates multiple doublet detection methods to address these issues. Chord had higher accuracy and stability than the individual approaches on different datasets containing real and synthetic data. Moreover, Chord was designed with a modular architecture port, which has high flexibility and adaptability to the incorporation of any new tools. Chord is a general solution to the doublet detection problem. For the unmet need to choose the suitable doublet detection method, an ensemble machine learning algorithm called Chord was developed, which integrates multiple methods and achieves higher accuracy and stability on different scRNA-seq datasets. [ABSTRACT FROM AUTHOR]

A graphic sequence π = (d1, d2, ..., dn) is said to be forcibly k-edge-connected if every realization of π is k-edge-connected. In this paper, we obtain a new sufficient degree condition for π to be forcibly k-edge-connected. We also show that this new sufficient degree condition implies a strongest monotone degree condition for π to be forcibly 2-edge-connected and a conjecture about a strongest monotone degree condition for π to be forcibly 3-edge-connected due to Bauer et al. (Networks, 54(2) (2009) 95–98), and also implies a strongest monotone degree condition for π to be forcibly 4-edge-connected. [ABSTRACT FROM AUTHOR]

This study proposes a novel approach to surface strain measurement for cylindrical rock specimens subjected to uniaxial compression using distributed fibre optic sensing technology. The capability and accuracy of this approach in measuring the full-field strain distribution of a rock specimen have been verified by a series of uniaxial compressive strength (UCS) tests on cylindrical specimens of aluminium alloy, sandstone, and granite. By analysing the experimental results, this new approach also has the potential of being utilized to detect the potential failure locations and sequence through strain localization zone variations and estimation of the development of crack opening displacement and rock fracturing characteristics during the loading and unloading process. Detailed installation procedures are provided for this study for assistance in the use of this new approach. The boundary issue of fibre measurements is identified, and solved by extending the bonding length of the measuring fibre. [ABSTRACT FROM AUTHOR]

There are limited studies in the development of testing apparatus on unsaturated soils due to the complex structure, tedious calibration process, and large demands on test time and skills. In this study, a novel multifunctional apparatus (MFA) has been designed and manufactured for testing the unsaturated soils. This state-of-the-art testing apparatus is based on modular design and can be configured to conduct a variety of tests such as pressure plate test, oedometer test, direct shear test, and triaxial creep test under suction-controlled conditions. This apparatus has a high-grade stainless-steel chamber which is used to measure the total volume changes of an unsaturated soil specimen in triaxial creep tests. Based on the calibration results, the creep coefficient for MFA is about half of the coefficient for a typical double-cell system. Additionally, the MFA is designed in a manner to enable testing specimens with different dimensions and to control soil suction based on different techniques. Typical calibration results, test procedures, and experimental results obtained from this apparatus are presented and discussed in detail. Finally, the performance of this apparatus is well verified by the experimental results. It is found that the MFA is capable of and reliable for performing above-mentioned tests and accurately investigating engineering behaviour of both saturated and unsaturated geomaterials. [ABSTRACT FROM AUTHOR]

Retention behavior of a flexible barrier in mitigating a granular flow is still an open problem not fully understood, especially due to the complexity of the granular material and the flexible barrier. Understanding the retention mechanism and quantifying the influencing factors of retention efficiency are desirable for optimizing the design and minimizing the maintenance cost of a debris-resisting flexible barrier. In this paper, a numerical model, based on the discrete element method, is presented, calibrated, and validated to analyze the interaction between a granular flow and a flexible net. A full-scale numerical simulation is first performed to compare with a large-scale physical modeling test in the literature and validate the applied parameters in the simulation. The interaction and deposition characteristics of the granular flow interacting with a flexible net are revealed. Afterward, parametric study is performed to investigate the effects of the internal friction angle (φ) of debris material and the relative mesh size of flexible net on the retention efficiency and clogging mechanism of a flexible barrier. The simulation results illustrate that the particle passing ratio (P) increases with increment of the friction angle of particles and enlargement of the mesh size of a flexible net. Both parameters have critical effects on the retention efficiency of a flexible barrier in intercepting a granular flow. Therefore, the friction angle and the particle size distribution characteristics of the debris material are suggested being used for optimization of the mesh size and more efficient design of debris-resisting flexible barriers. [ABSTRACT FROM AUTHOR]

A home-made small-sized Raman spectrometer combined with machine learning algorithms was used to study and identify healthy and multi-period osteoarthritis (OA) canine knee joints. Nine canines were equally divided into three groups according to the post-operative (OA modeling) time of 2-month, 3-month and 7-month. Other two normal canines were used as control. It was found that the degeneration degree of cartilage was positively correlated with post-operative time by doing anatomical analysis. The mixed Raman spectra of cartilage and subchondral bone were collected and analyzed, which reveals subchondral bone demineralization and carbonate ion substituting into the apatite mineral during OA. Raman spectra combined with principal component analysis (PCA) further disclosed that collagen matrix became unordered, both content ratios of amide I/matrix and phenylalanine/matrix in OA cartilage and subchondral bone increased. Based on the PCA getting five principal components, all groups were effectively discriminated by Fisher discriminant analysis (FDA) with high accuracy of 91.07% for the validation set, as well as 95.45% for the test set. It suggests that Raman spectroscopy combined with machine learning is capable to become an effective tool to achieve in situ identification of multi-period OA with high accuracy and preclinical significance. [ABSTRACT FROM AUTHOR]

A nonincreasing sequence π = (d1,...,dn) of nonnegative integers is a graphic sequence if it is realizable by a simple graph G on n vertices. In this case, G is referred to as a realization of π. Given a graph H, a graphic sequence π is potentially H-graphic if π has a realization containing H as a subgraph. For graphs G1 and G2, the potential-Ramsey number rpot(G1, G2) is the smallest integer k such that for every k-term graphic sequence π, either π is potentially G1-graphic or the complementary sequence π ¯ = (k − 1 − d k , ⋯ k − 1 − d 1) is potentially G2-graphic. For 0 ≤ k ≤ ⌊ t 2 ⌋ , denote K t − k to be the graph obtained from Kt by deleting k independent edges. If k = 0, Busch et al. (Graphs Combin., 30(2014)847–859) present a lower bound on rpot(G, Kt) by using the 1-dependence number of G. In this paper, we utilize i-dependence number of G for i ≥ 1 to give a new lower bound on rpot(G, K t − k ) for any k with 0 ≤ k ≤ ⌊ t 2 ⌋ . Moreover, we also determine the exact values of rpot(Kn, K t − k ) for 1 ≤ k ≤ 2. [ABSTRACT FROM AUTHOR]

In mountainous western China, a large number of granular materials are used as construction materials in high-fill embankments. These granular fill materials in the embankments are typically unsaturated owing to the arid and semi-arid climates in this area. However, previous studies on unsaturated soils primarily focus on fine-grained soils. In this study, a series of triaxial tests were performed to determine the critical state parameters of a granular fill material in q– p ¯ , v–ln p ¯ , and vw–ln p ¯ planes. An upgraded double-cell triaxial system (DCTS) was used in net confining pressures ranging from 0 to 450 kPa and matric suctions ranging from 0 to 160 kPa. This study demonstrates the good performance of the upgraded DCTS in unsaturated soil testing. Experimental results show that the critical state lines are almost parallel to those of saturated soil in the q– p ¯ plane, suggesting that the friction angle is independent of suction. The total cohesion and hence the shear strength increase with suction. In the v–ln p ¯ plane, both the intercept and slope of the critical state line increase with suction. Finally, it is observed that the intercept and slope decrease with increasing suction in the vw–ln p ¯ plane. [ABSTRACT FROM AUTHOR]

Debris flow normally occurs after heavy rains in mountainous regions with multiple surges. Flexible barriers are installed in torrents to intercept debris flows in an early stage. For the safer design of a flexible barrier installed in the upstream, the forces on the barrier invaded by debris flows should be taken into consideration. An outdoor physical modelling facility was utilized to study the interaction between debris flows and a flexible barrier. Three continuous debris flow impact tests were conducted to investigate the performance of a flexible barrier affected and overflowed by multiple surges of debris flow. A parameter named Initial Block Ratio (IBR) is introduced in this study to describe the initial condition of a flexible barrier filled by the earlier debris flow surges. By analysing the results of these tests, the dynamic response of a flexible barrier under the impact of multiple surges of debris flow is studied, and the influence of IBR on the interaction of debris flow with the flexible barrier is investigated. Based on the findings of the experimental study, a new simple method is proposed to calculate the loads on a filled flexible barrier overflowed by debris flow. By comparing with the measured impact force in the overflow test, this method has a good performance and can be utilized in design analysis with further calibration. [ABSTRACT FROM AUTHOR]

Considering the increasing applications of micropile systems in seismically active areas, a better understanding of their seismic performance and the key controlling factors is of high significance. This paper presents experimental investigations of the seismic performance of a small-scale physical model of micropiles under seismic ground motions. Shaking table tests were performed on a 4 × 4 group of vertical micropiles embedded in loose sand. Horizontal acceleration time histories recorded from the 1940 El Centro earthquake and 1995 Kobe earthquake were applied to the base of the soil container. The response of the physical model was monitored in terms of horizontal accelerations at different levels and bending moments induced in the micropiles. The experimental results indicate that in all shaking events, the magnitudes of horizontal accelerations on the soil surface and the pile cap were amplified with respect to the input motion. Bending moments were induced in the micropiles and peaked at the mid-depth. It was also found that inclining the micropiles led to improvement in their seismic performance, reducing both the acceleration response on soil surface and pile cap, and the induced bending moments in the micropiles. Finite element simulations of shaking table tests have been performed, and the results are in reasonable agreement with observations from the experiments. [ABSTRACT FROM AUTHOR]

A simple graph G is a 2-tree if G = K3, or G has a vertex v of degree 2, whose neighbors are adjacent, and G — v is a 2-tree. Clearly, if G is a 2-tree on n vertices, then E(G) = 2n — 3. A non-increasing sequence π = (d1,...,dn) of nonnegative integers is a graphic sequence if it is realizable by a simple graph G on n vertices. [Acta Math. Sin. Engl. Ser., 25, 795–802 (2009)] proved that if k ≥ 2, n ≥ and π = (d1,...,dn) is a graphic sequence with , then p has a realization containing every 1-tree (the usual tree) on k vertices. Moreover, the lower bound (k — 2)n is the best possible. This is a variation of a conjecture due to Erdos and Sós. In this paper, we investigate an analogue problem for 2-trees and prove that if k ≥ 3 is an integer with k = i (mod3), π = (d1,...,dn is a graphic sequence with , then π has a realization containing every 2-tree on k vertices. Moreover, the lower bound max is the best possible. This result implies a conjecture due to [Discrete Math. Theor. Comput. Sci., 17(3), 315–326 (2016)]. [ABSTRACT FROM AUTHOR]

The site formation for the construction of a new airport in a mountainous region is typically performed by cutting and filling a hill section. The fill materials are subjected to seasonal changes and large variations in water content. The water content change renders the fill material to be characterized as unsaturated or saturated. This study aims to investigate the influence of matric suction on the time-dependent compression behavior of one local soil as a fill material for the construction of a new runway of an airport in Chongqing city, a mountainous region in China. A series of unsaturated drained triaxial tests were conducted on this coarse-grained soil to obtain the relationship between the effective stress parameter, χ, and the matric suction. Subsequently, multistaged compression tests were performed on this soil using a newly designed suction-controlled oedometer apparatus. The influence of suction on the time-dependent compression behavior of the fill material is emphasized. The results indicate that the matric suction can increase the compression stiffness, and that the unloading–reloading index varies nonlinearly with suction. A linear relationship between the time-dependent compression coefficient and normalized effective vertical loading is established. The linear relationship is subsequently used to predict the time-dependent compression coefficient to describe the time-dependent behavior of the fill under unsaturated conditions. Further, a nonlinear function based on the work of Yin (Géotechnique 49(5):699–707, 1999) is adopted to describe the development of time-dependent compression. The results indicate that the prediction obtained from the two newly proposed methods are promising, and can predict the nonlinear time-dependent compression behavior of this coarse-grained soil. [ABSTRACT FROM AUTHOR]

Fourier transform infrared imaging (FTIRI) can be used to obtain the composition and structure information of sample. Here, FTIRI combined with spectral polarization analysis method was applied to investigate the fine anisotropy of bovine nasal cartilage (BNC). The upper BNC tissue was sliced into a three-dimensional (3D) block with three planes (XY, YZ, and XZ) parallel to horizontal section, forward section, and lateral section, respectively. The anisotropy of collagen fiber in BNC was represented by the absorbance of amide II (1590–1500 cm−1) at different polarization directions. It was found that collagen fiber showed little anisotropy in plane XY, XZ, and along the direction Z in plane YZ. It was more important that collagen fiber showed strong anisotropy along direction Y in plane YZ (transverse axis) of BNC, possibly including arched or wavy fiber orientation even a mixture of both in nasal septum top end. Two anisotropic deflections ranging from 600 to 930 μm and from 2680 to 2980 μm were quantitatively calculated. This study is of important significance for further understanding the physiological structure of nasal septum and provides remarkable experimental support for being a good transplant material in cartilage reshaping studies. [ABSTRACT FROM AUTHOR]

In most marine reclamation projects, sand fill is placed directly on soft marine seabed soils. The sand particles can easily penetrate into the soft marine soils, and the soft soil can also move into the pore spaces inside the sand at the initial contact interface between the sand and the soft marine soil. In this case, the permeability and the volume of the sand above the initial surface are reduced. To avoid this problem, a geotextile separator is often placed on the surface of the soft marine soils before placing the sand. In this study, a two-dimensional physical model is utilized to study the geotextile separator effects. The initial conditions of a clayey soil, sand fill, and surcharge loading were kept the same in the physical model test with the only difference being that a geotextile separator was either placed on the clay surface or omitted. The settlements of the initial interface were recorded and compared for the two cases without or with the geotextile separator. The particle size distribution of the soils taken across the interface zone for different time durations was then measured, analyzed, and compared. Based on an analysis of the results, the sand percolation depth was 40 mm and fine particle suffusion was apparent when the sand was placed directly on the marine slurry surface without a geotextile separator. However, when a geotextile separator was used sand percolation was avoided, and the fine particle suffusion was effectively diminished. A relative fine particle fraction is defined to illustrate the migration of fine particles from the clay to the sand soils. The fine particle percentages of the Hong Kong Marine Deposits–sand mixtures were calculated for the cases with and without a geotextile separator using an empirical formula and micromechanical modeling to obtain a better understanding of the effects of geotextile separators in practice. [ABSTRACT FROM AUTHOR]

Let Ks,t be the complete bipartite graph with partite sets {x1, ..., xs} and {y1, ..., yt}. A split bipartite-graph on (s + s′) + (t + t′) vertices, denoted by SBs + s′, t + t′, is the graph obtained from Ks,t by adding s′ + t′ new vertices xs + 1, ..., xs + s′}, yt + 1, ..., yt + t′ such that each of xs + 1, ..., xs + s′; is adjacent to each of y1, ..., yt and each of yt + 1, ..., yt + t′ is adjacent to each of x1, ..., xs. Let A and B be nonincreasing lists of nonnegative integers, having lengths m and n, respectively. The pair (A; B) is potentially SBs + s′, t + t′-bigraphic if there is a simple bipartite graph containing SBs + s′, t + t′ (with s + s′ vertices x1, ..., xs + s′ in the part of size m and t + t′ vertices y1, ..., yt + t′ in the part of size n) such that the lists of vertex degrees in the two partite sets are A and B. In this paper, we give a characterization for (A; B) to be potentially SBs + s′, t + t′-bigraphic. A simplification of this characterization is also presented. [ABSTRACT FROM AUTHOR]

A non-increasing sequence π = (d1, d2,..., dn) of nonnegative integers is said to be potentially hamiltonian-graphic (resp. potentially pancyclic-graphic) if it is realizable by a simple graph on n vertices containing a hamiltonian cycle (resp. containing cycles of every length from 3 to n). A.R. Rao and S.B. Rao (J. Combin. Theory Ser.B, 13(1972), 185-191) and Kundu (Discrete Math., 6(1973), 367-376) presented a characterization of π = (d1, d2,..., dn) that is potentially hamiltonian-graphic. S.B. Rao (Lecture Notes in Math., No. 855, Springer Verlag, 1981, 417–440, Unsolved Problem 2) further posed the following problem: present a characterization of π = (d1, d2,..., dn) that is potentially pancyclic-graphic. In this paper, we first give solution to this problem for the case of 4 ≤ n ≤ 11. Moreover, we also show that a near regular graphic sequence π = (d1, d2,..., dn) with dn ≥ 3 is potentially pancyclic-graphic. [ABSTRACT FROM AUTHOR]

For accurately measuring the volume change of a soil specimen under monotonic and cyclic loading, a new double-cell system is described in this paper. This newly designed double-cell system is equipped with local linear variable differential transformers (LVDTs) and can also accommodate large specimens. Careful calibrations, including the effect of cell pressure change, "creep" of inner cell volume, the effect of temperature fluctuation, and loading ram movement, are presented and discussed by comparing the possible errors with those of other existing apparatuses. This system exhibits superior performances in volume change due to cell pressure, temperature sensitivity, and accuracy of loading ram movement. Three monotonic compression tests under saturated and unsaturated conditions were conducted to evaluate the performance of volume change measurement and local LVDTs. Moreover, six different frequencies were used to verify the workability and accuracy of this system in conducting cyclic testing. The results indicate that the maximum frequency this system can achieve, with a satisfactory precision, is 0.2 Hz, which is four times higher than what the previous systems could achieve. Finally, several suggestions are made on how to improve the system's performance even better. [ABSTRACT FROM AUTHOR]

Flexible barriers have been widely applied in rockfall mitigation in recent years. However, the behavior of flexible barriers under the impact of boulders is still not fully understood. To investigate the interaction between a flexible barrier and a falling boulder, a large-scale physical modeling device has been constructed at a site in Hong Kong. Using this device, large-scale impact tests using boulders with different diameters were conducted. Test results are presented and analyzed in this paper. The motion of the boulder during impact is traced and analyzed. The impact forces on the flexible ring net and the supporting structures are measured and compared. From the comparison, the impact reduction rates (IRR) of boulders with different diameters are calculated. Moreover, a simple approach for estimating the impact loading of a boulder on a flexible barrier is proposed in this study. This approach is calibrated and verified using measured impact forces in the tests. [ABSTRACT FROM AUTHOR]

Geogrid has been extensively used in geotechnical engineering practice due to its effectiveness and economy. Deep insight into the interaction between the backfill soil and the geogrid is of great importance for proper design and construction of geogrid reinforced earth structures. Based on the calibrated model of sand and geogrid, a series of numerical pullout tests are conducted using PFC under special considerations of particle angularity and aperture geometry of the geogrid. In this work, interface characteristics regarding the displacement and contact force developed among particles and the deformation and force distribution along the geogrid are all visualized with PFC simulations so that new understanding on how geogrid-soil interaction develops under pullout loads can be obtained. Meanwhile, a new variable named fabric anisotropy coefficient is introduced to evaluate the inherent relationship between macroscopic strength and microscopic fabric anisotropy. A correlation analysis is adopted to compare the accuracy between the newly-proposed coefficient and the most commonly used one. Furthermore, additional pullout tests on geogrid with four different joint protrusion heights have been conducted to investigate what extent and how vertical reinforcement elements may result in reinforcement effects from perspectives of bearing resistance contribution, energy dissipation, as well as volumetric response. Numerical results show that both the magnitude and the directional variation of normal contact forces govern the development of macroscopic strength and the reinforcing effects of joint protrusion height can be attributed to the accelerated energy dissipation across the particle assembly and the intensive mobilization of the geogrid. [ABSTRACT FROM AUTHOR]

The split graph K V K on r+ s vertices is denoted by S . A graphic sequence π = ( d , d , ···, d ) is said to be potentially S -graphic if there is a realization of π containing S as a subgraph. In this paper, a simple sufficient condition for π to be potentially S -graphic is obtained, which extends an analogous condition for p to be potentially K -graphic due to Yin and Li (Discrete Math. 301 (2005) 218-227). As an application of this condition, we further determine the values of σ( S , n) for n ≥ 3 r + 3 s - 1. [ABSTRACT FROM AUTHOR]

A graph G is a k-tree if either G is the complete graph on k + 1 vertices, or G has a vertex v whose neighborhood is a clique of order k and the graph obtained by removing v from G is also a k-tree. Clearly, a k-tree has at least k + 1 vertices, and G is a 1-tree (usual tree) if and only if it is a 1-connected graph and has no K-minor. In this paper, motivated by some properties of 2-trees, we obtain a characterization of k-trees as follows: if G is a graph with at least k + 1 vertices, then G is a k-tree if and only if G has no K-minor, G does not contain any chordless cycle of length at least 4 and G is k-connected. [ABSTRACT FROM AUTHOR]

This work focuses on the uniqueness of rate-dependency, creep and stress relaxation behaviors for soft clays under one-dimensional condition. An elasto-viscoplastic model is briefly introduced based on the rate-dependency of preconsolidation pressure. By comparing the rate-dependency formulation with the creep based formulation, the relationship between rate-dependency and creep behaviors is firstly described. The rate-dependency based formulation is then extended to derive an analytical solution for the stress relaxation behavior with defining a stress relaxation coefficient. Based on this, the relationship between the rate-dependency coefficient and the stress relaxation coefficient is derived. Therefore, the uniqueness between behaviors of rate-dependency, creep and stress relaxation with their key parameters is obtained. The uniqueness is finally validated by comparing the simulated rate-dependency of preconsolidation pressure, the estimated values of secondary compression coefficient and simulations of stress relaxation tests with test results on both reconstituted Illite and Berthierville clay. [ABSTRACT FROM AUTHOR]

The small strain stiffness of soils has a significant role in geotechnical design and analysis. In laboratory, the small strain behavior is examined by different techniques including the bender element method for measuring the maximum shear modulus and local displacement transducer (LDT) for measuring Young's modulus at small strains. However, most commonly used LDTs are based on electrical components and have limitations, such as electromagnetic interference and possibility of short circuit in the presence of water. To overcome these limitations, in the present study, a conventional triaxial apparatus has been modified to measure and study the stress-strain behavior of soils at small strains. The major modifications include addition of piezoceramic sensors (bender elements) for measuring the maximum shear modulus and fiber Bragg grating (FBG) sensor-based local displacement transducers (FBG-LDTs) for measuring the stress-strain behavior at small strains. The modified triaxial apparatus has been used to conduct several tests on a completely decomposed granite soil from a site in Hong Kong. The stress-strain behaviors measured by the newly developed FBG-LDTs and an external displacement transducer are compared and discussed. In particular, the shear modulus values obtained using the bender elements, FBG-LTDs, and the external displacement transducer are also compared, discussed, and evaluated. The comparison and assessment show that the FBG-LTDs are more suitable for measuring the small strain behavior of soils. [ABSTRACT FROM AUTHOR]

Let n ≥ r, let π = ( d1, d2, ..., dn) be a non-increasing sequence of nonnegative integers and let Kr+1 − e be the graph obtained from Kr+1 by deleting one edge. If π has a realization G containing Kr+1 − e as a subgraph, then π is said to be potentially Kr+1 − e-graphic. In this paper, we give a characterization for a sequence π to be potentially Kr+1 − e-graphic. [ABSTRACT FROM AUTHOR]

Pullout resistance of a soil nail is a critical parameter in design and analysis for geotechnical engineers. Due to the complexity of field conditions, the pullout behaviour of cement grouted soil nail in field is not well investigated. In this work, a number of field pullout tests of pressure grouted soil nails were conducted to estimate the pullout resistance of soil nails. The effective bond lengths of field soil nails were accurately controlled by a new grouting packer system. Typical field test results and the related comparison with typical laboratory test results reveal that the apparent coefficient of friction (ACF) decreases with the increase of overburden soil pressure when grouting pressure is constant, but increases almost linearly with the increase of grouting pressure when overburden pressure (soil depth) is unchanged. Water contents of soil samples at soil nail surfaces show obvious reductions compared with the results of soil samples from drillholes. After soil nails were completely pulled out of the ground, surface conditions of the soil nails and surrounding soil were examined. It is found that the water content values of the soil at the soil/nail interfaces decrease substantially compared with those of soil samples extracted from drillholes. In addition, all soil nails expand significantly in the diametrical direction after being pulled out of ground, indicating that the pressurized cement grout compacts the soil and penetrates into soil voids, leading to a corresponding shift of failure surface into surrounding soil mass significantly. [ABSTRACT FROM AUTHOR]

Bilirubin (BR) aggregating at liquid/liquid interface was firstly detected by Fourier transform infrared (FTIR) imaging/spectroscopy combining with ultraviolet-visible (UV/Vis) absorption spectra. In the UV/Vis absorption spectra of BR aggregate, a new shoulder appeared at 474 nm, and BR absorption maximum underwent red shift from 450 nm to a longer wavelength at 497 nm, which indicates that BR aggregate was formed at the interface. Meanwhile, the BR molecule structure changed or conformation torsion, that is, the increase in orbit overlap or dihedral angle and the enhancement of exciton coupling. In the study of FTIR imaging/spectroscopy, the hydrogen bond-sensitive infrared bands of BR aggregate showed remarkable changes in band shift and intensity compared with those of BR powder, suggesting that the intramolecular hydrogen bonds broke out and internal structure changed. These new findings will be helpful for understanding of the BR molecular interaction, transportation, complex with serum albumin and metal ions, and the effect of BR aggregating on biomembrane and human tissues. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The split graph K + $$\overline {{K_s}} $$ on r+ s vertices is denoted by S. A non-increasing sequence π = ( d, d, ..., d) of nonnegative integers is said to be potentially S-graphic if there exists a realization of π containing S as a subgraph. In this paper, we obtain a Havel-Hakimi type procedure and a simple sufficient condition for π to be potentially S-graphic. They are extensions of two theorems due to A.R.Rao (The clique number of a graph with given degree sequence, Graph Theory, Proc. Symp., Calcutta 1976, ISI Lect. Notes Series 4 (1979), 251-267 and An Erdős-Gallai type result on the clique number of a realization of a degree sequence, unpublished). [ABSTRACT FROM AUTHOR]

A graphic sequence π = ( d, d, . . . , d) is said to be potentially K-graphic if there is a realization of π containing K as a subgraph, where K is the 1 × 1 × s complete 3-partite graph. In this paper, a simple characterization of potentially K-graphic sequences for s ≥ 2 and n ≥ 3 s + 1 is obtained. This characterization implies Lai's conjecture on σ( K, n), which was confirmed by J.H. Yin, J.S. Li and W.Y. Li, and the values of σ( K, n) for s ≥ 4 and n ≥ 3 s + 1, where K is the 2 × s complete bipartite graph. [ABSTRACT FROM AUTHOR]

The association of viral mutations and haplotypic carriages with mutations in the preS region of hepatitis B virus (HBV) genotypes B and C with hepatocellular carcinoma (HCC) is of great significance for the prediction of this malignancy, but it remains obscure. We analyzed the preS sequences of HBV genotypes B and C from 1172 HBV-infected subjects including 231 patients with HCC. As compared with the HBV-infected subjects without HCC, C2875T, G2946C, A3054C, C3060A, T3066C, C3116T, A3120C, G3191A, A1C, C7A, C10A, A31C, C76T, G105C, and G147C in both genotypes were significantly associated with increased risks of HCC. C2875A, G2950A, G2951A, A3054T, C3060T, T3066A, T3069G, A3120T, and G3191C were significantly associated with increased risks of HCC in genotype C, whereas these mutations were inversely associated with HCC in genotype B. Multivariate regression analyses showed that C76A/T was a novel factor independently associated with an increased risk of HCC, as compared with those without HCC. The frequencies of haplotypes 2964A-3116T-preS2 start codon wild-type-7C, 2964C-3116T-7A-76C, and 2964A-3116T-7C-76A/T were significantly higher in the patients with HCC ( P<0.001), whereas a haplotypic carriage with a single mutation and another three wildtypes were inversely associated with HCC. Conclusively, the association of HBV mutations in the preS region with HCC depends on HBV genotype and haplotypic carriage with two or more mutations that are each associated with an increased risk of HCC independently. [ABSTRACT FROM AUTHOR]

A physical model facility was designed, built, and setup for conducting model tests on a composite foundation in a soil ground. The model tests were carried out on a composite foundation with different combinations of vertical reinforcement elements in the same soil ground. Via the analysis of the collected data the characteristics of the composite foundation with different reinforcing elements were obtained, including the characteristics of load-settlement curves, column stresses, stresses of the inter-column soil, pile-soil stress ratio, and load-sharing ratios of columns and soil. Results from the model tests reveal the mechanism of a composite foundation with different reinforcing elements quantitatively. It is concluded that both a composite foundation with a combination of steel pipe pile and sand column and that with a combination of concrete pile and lime column have a higher bearing capacity than the composite foundation with only sand columns with the same conditions of soil ground and loading. A composite foundation with lime column and sand column embodies no much better performance than that with sand columns only. [ABSTRACT FROM AUTHOR]

For most soft soil, the consolidation process and the creep process were coupled and the character of settlement time curve was obtained by the consolidation test at the same time. A simple and continuous function was presented to express the whole process of consolidation including immediate settlement stage, the primary consolidation stage and the secondary consolidation stage. And the features of the continuous function were analyzed. The results of the long-term (duration to 18 months) consolidation test on clays from the Chek Lap Kok formation proved the rightness of the method. In the end, the parameter meanings of the continuous function were discussed. [ABSTRACT FROM AUTHOR]

This paper presents a backward transfer-matrix method for the elastic analysis of layered solids with an imperfect bonding at the layer interfaces. Literature review reveals that the conventional transfer-matrix method has an intrinsic fault which leads to ill-conditioned matrices for thick layers and accumulative numerical errors for a large number of layers and that there are a few publications available in the relevant literature regarding analytical analysis of layered solids by taking into account the effects of imperfectly bonded interfaces. The backward transfer-matrix method adopted in this paper completely overcomes the ill-posedness associated with the conventional transfer-matrix method and fully retains the highest efficiency of the classical transfer-matrix concept for analytical formulation of solutions in layered elastic solids with imperfectly bonded interfaces. Numerical results indicate that there is no problem in the numerical evaluation of the solutions with high accuracy and efficiency, and that the interfacial bonding conditions have a significant effect on the elastic response of layered solids due to external loading. [ABSTRACT FROM AUTHOR]

The use of horizontal drains assisted by vacuum loading is an effective method for speeding up the consolidation of dredged soil slurry. However, few studies developed models for the large strain consolidation of clayey slurry with prefabricated horizontal drains (PHDs) under self-weight and vacuum loading considering the effects of nonlinear compression and creep. This study introduces a PHD-assisted finite strain consolidation model considering nonlinear compression and limited creep by incorporating an improved elasto-viscoplastic constitutive equation. Firstly, the governing equations for the consolidation of very soft soil with PHDs were derived and solved by the finite-difference method. Subsequently, the proposed consolidation model was verified by comparing the calculations with the finite element solutions, a laboratory model test, and a field trial performed in Hong Kong. Good agreement with the numerical solutions and measured results indicates that the proposed model can capture the consolidation features with PHD combining staged filling and time-dependent vacuum loading. Then, the proposed model was used to estimate a self-weight consolidation test and field test in Japan to show the performance of the proposed model. Finally, parametric studies were conducted to explore the influence of nonlinear compression and creep on the consolidation of soft soil with PHDs. [ABSTRACT FROM AUTHOR]