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This paper presents the results of field tests performed to investigate the installation effects of pre-bored grouted planted (PGP) pile in deep clayey soil. The variation of horizontal soil displacements, excess pore water pressures and lateral soil pressures was measured in the PGP pile installation process. The test results show that the drilling and grouting process induced large horizontal soil displacements in the soil within a radial distance of 2 d (d is pile diameter), and the maximum horizontal soil displacements induced by the drilling and grouting process were smaller than 15.9 mm when the radial distance reached 4–5 d. Moreover, the horizontal soil displacements decreased along the soil layer depth, as the superficial soil layers were of small deformation modulus and lateral soil pressure. The drilling process brought large excess pore water pressures in the soil when the radial distance was less than 3 d, and the excess pore water pressures induced by the drilling stage were all less than 55 kPa when the radial distance reached 4–6 d. The drilling process also induced some lateral soil pressure increases in the soil within a radial distance of 3 d, while the measured maximum lateral soil pressure increases were smaller than 10.9 kPa when the radial distance increased to 4 d. On the whole, the excess pore water pressures and lateral soil pressure increases induced by the installation of PGP pile were much smaller than that induced by the installation of driven PHC pile. Moreover, the horizontal soil displacements, excess pore water pressures and lateral soil pressure increases induced by the installation of PGP pile all recovered rapidly after the installation of pile, as the cemented soil in the pile hole was in liquid state after the drilling and grouting stage. [ABSTRACT FROM AUTHOR]

This paper presents the results of field tests performed to investigate the behavior of pre-bored grouted planted nodular (PGPN) pile embedded in deep clayey soil. The test piles were all instrumented to measure the shaft and tip resistance and to determine the load transfer along the pile shaft. The test results show that the displacement necessary to fully mobilize the shaft resistance of PGPN pile is in the range of 1.83–3.32% D (D is pile diameter), and that the ultimate skin frictions of grout–soil interface of different soil layers are larger than the conventional proposed ultimate skin frictions for non-displacement piles. Furthermore, the pile tip resistance accounts for about 16% of the total applied pile head load corresponding to a pile head displacement of 0.1 D, and the pile tip resistance continues to increase after tip displacement reaches 5% of pile tip diameter. [ABSTRACT FROM AUTHOR]

The pre-bored grouted planted pile is a new type of composite pile foundation that consists of a precast concrete pile and the surrounding cemented soil. A series of shear tests were conducted in a specific shear test apparatus to investigate the shaft capacity of the different pile-soil interfaces. The test results show that the frictional capacity of the cemented soil-sand interface is controlled mainly by the sand properties, while the strength of the cemented soil slightly influences the interface properties by affecting the normalized roughness coefficient Rn. The frictional capacity of the concrete-sand interface is similar to the frictional capacity of the cemented soil-sand interface, and the existence of mud cake layer virtually hampers the frictional properties of the interface. The maximum skin friction of the concrete-cemented soil interface increases approximately linearly with the increasing cemented soil strength, and the value of the maximum skin friction is much larger than that of the cemented soil-sand interface of identical cemented soil strength, which demonstrates the integrity of the pre-bored grouted planted pile in the load transfer process. [ABSTRACT FROM AUTHOR]

A group of field tests and three-dimensional finite element simulation were used to investigate the behavior of the pre-bored grouting planted pile under compression and tension; moreover, a group of shear tests of the concrete-cemented soil interface was carried out to study the frictional capacity of the pile-cemented soil interface. The load-displacement response, shaft resistance and mobilized base load were discussed based on the measured and computed results. The measured and computed results show that the frictional capacity of the cemented soil-soil interface is better than the frictional capacity of the concrete-soil interface. The frictional capacity of the concrete-cemented soil interface is mainly controlled by the properties of the cemented soil, and the ultimate skin friction of the concrete-cemented soil interface is much larger than that of the cemented soil-soil interface. The frictional capacity of the soil layer close to the enlarged base is also promoted because of the compaction of the enlarged base. The enlarged cemented soil base can promote the behavior of the pile foundation under tension, and the enlarged cemented soil base undertakes approximately 26.3% of the total uplift load under the ultimate bearing capacity in this research. [ABSTRACT FROM AUTHOR]

The pre-bored grouted planted (PGP) pile shaft consists of a core PHC pile and the surrounding cemented soil column. The shaft capacity of PGP pile is controlled by the PHC pile–cemented soil–soil interface. In this paper, the effect of curing time on the frictional capacity of smooth concrete pipe pile–cemented soil interface was investigated through pile–soil interface shear tests. The test results show that the peak skin friction of pipe pile–cemented soil interface increased with the curing time. Nevertheless, the normalized peak skin friction (peak skin friction/cemented soil strength) of interface decreased with the curing time. The thickness of the cemented soil layer had a large effect on the residual skin friction of pipe pile–cemented soil interface. The scale effect also existed in the smooth concrete pipe pile–cemented soil interface shear tests, as the stiffness and shear strength of interface would decrease with the pipe pile diameter, which would eventually induce the decrease of radial confining pressure of the interface. [ABSTRACT FROM AUTHOR]

A static drill rooted nodular pile is a new type of composite pile foundation with high bearing capacity, and mud emissions can be largely reduced using the static drill rooted method. This report presents a model test on the behavior of this composite pile in a test box. The load-displacement response, axial force, skin friction, and mobilized base load are discussed in the report; in particular, the force in the cemented soil was investigated based on the measured data. Moreover, the finite element software ABAQUS was used to help investigate this behavior more thoroughly. It was determined that the function of the cemented soil around the pile shaft was different from that at the enlarged pile base; the stress in the cemented soil around the shaft increased suddenly when nearing the pile base; the ultimate skin friction obtained in the model test was larger than that estimated in the field test; and the relative displacement between the precast nodular pile and the cemented soil could be ignored during the loading process, which corresponded to the result of the field test and demonstrated that the nodular pile and cemented soil act as one entity during the loading process. [ABSTRACT FROM AUTHOR]

Previous experimental tests on clays have confirmed the non-coincidence of principal strain increments with principal stress axes even though the stress rate is colinear with the current stress. To simulate the non-coaxial behavior of saturated clay subjected to monotonic proportional or non-proportional loading with constant principal stress rate directions, an anisotropic hypoplastic model is presented in this paper. The model is proposed by incorporating an improved anisotropic asymptotic state boundary surface (ASBS) and a non-coaxial asymptotic strain rate direction into the original explicit-ASBS hypoplastic model. The non-coaxial flow results from a non-coaxial stress rate defined by a Gram-Schmidt orthogonalization process based on a reference stress tensor. The capability of the proposed model is demonstrated by simulating the test data performed in hollow cylindrical apparatus (HCA) on Wenzhou clay and Shanghai clay with different drainage conditions and initial consolidation states. In addition, a series of numerical stress probing tests have been conducted to gain further insights into the properties of the proposed model. [ABSTRACT FROM AUTHOR]

This paper presents the results of field tests performed to investigate the compressive bearing capacity of pre-bored grouted planted (PGP) pile with enlarged grout base focusing on its base bearing capacity. The bi-directional O-cell load test was conducted to evaluate the behavior of full scale PGP piles. The test results show that the pile head displacements needed to fully mobilize the shaft resistance were 5.9% and 6.4% D (D is pile diameter), respectively, of two test piles, owing to the large elastic shortening of pile shaft. Furthermore, the results demonstrated that the PHC nodular pile base and grout body at the enlarged base could act as a unit in the loading process, and the enlarged grout base could effectively promote the base bearing capacity of PGP pile through increasing the base area. The normalized base resistances (unit base resistance/average cone base resistance) of two test piles were 0.17 and 0.19, respectively, when the base displacement reached 5% Db (Db is pile base diameter). The permeation of grout into the silty sand layer under pile base increased the elastic modulus of silty sand, which could help to decrease pile head displacement under working load. [ABSTRACT FROM AUTHOR]

The rigid pile composite foundation is widely used in highway projects in soft soil area as it can effectively increase the bearing capacity and stability of the foundation. While the research on the behavior and failure mode of rigid pile composite foundation under embankment is not enough, instability failure of rigid pile composite foundation often occurs in practical projects. This paper presents a centrifuge model test to investigate the load transfer mechanism, settlement characteristic and failure mode of rigid pile composite foundation under embankment. The test results show that: the soil displacement of different region in rigid pile composite foundation was different, obvious vertical displacement occurred in the soil under the center of embankment and the horizontal displacement was very small in this region; both vertical and horizontal displacement occurred in the soil under the shoulder of embankment; and obvious horizontal displacement occurred in the soil under the slope toe of embankment; moreover, ground heave also occurred near the slope toe of embankment. The soil displacement in rigid pile composite foundation had a large influence on the stress characteristic and failure mode of rigid piles, the compressive failure and bending failure would probably occur for the piles under the center and shoulder of the embankment, respectively, and the tension-bending failure would probably occur for the piles under the slope toe of embankment. The different failure modes of piles at different regions should be considered in the design of rigid pile composite foundation under embankment. The test results can be used to improve the design method for rigid pile composite foundation under embankment in practical projects. [ABSTRACT FROM AUTHOR]

Analytical solutions for the steady-state seepage field in a finite seabed under homogeneous and isotropic conditions with a drained circular lined tunnel are developed. A numerical model is established using the COMSOL Multiphysics software to verify the solutions presented in this study, and strong agreement is found. A parameter analysis considering the seabed thickness, coefficient of permeability, tunnel burial depth and lining thickness is presented. The results indicate that the error induced by ignoring the thickness of the seabed cannot be neglected when the tunnel is close to the bottom of the seabed. [ABSTRACT FROM AUTHOR]

In this study, analytical solutions are developed to assess the hydraulic and structure responses of underwater tunnels by considering the tidal loading in conjunction with water ingress. Two scenarios are considered, that is, the surface water fluctuation (SWF) and groundwater variation (GWV). A single-step scheme is put forward to obtain the exact horizontal displacement developed at the springline with high efficiency. The proposed analytical method is verified by comparing the result from numerical simulations. A detailed parameter analysis is presented to investigate the effect of soil properties on the ground and tunnel behaviors as well as the discrepancies between these two hydraulic loadings. This study reveals that the underwater tunnel tends to act as drainage in the SWF condition whereas blockage for GWV. Much more intensive hydraulic and structure responses are observed under SWF than GWV, but both cases lead to slight tunnel deformations. [ABSTRACT FROM AUTHOR]

This paper investigated the installation effects of a driven prestressed high-strength concrete (PHC) nodular pile in deep soft clay through full-scale tests, and the behavior of a driven PHC nodular pile is analyzed based on the field test results. The test results demonstrated that the driven PHC nodular pile installation process induced significant disturbance in the surrounding soil. The excess pore water pressures (Δu) that were induced by the installation of a driven PHC nodular pile were larger than the Δu that were induced by the installation of a driven PHC pipe pile. The driven PHC nodular pile installation caused significant Δu in the soil down to 2 m below the pile base, and the Δu became much smaller in the soil at 4 m below the pile base. The Δu dissipated slowly in the soft clay layers, and the Δu in the surficial soil layers dissipated faster than that in the deep soil layers. The nodules along the PHC nodular pile shaft could increase the pile shaft capacity. The measured shaft resistances of 350(400)-mm PHC nodular piles were 1.17–1.18 times the calculated shaft resistances of 350-mm PHC pipe piles in soft clay layers. [ABSTRACT FROM AUTHOR]

The saturated hydraulic conductivity ( K s ) of soil is characterized by strong spatial variability and often decreases with depth. The main objective of this paper is to investigate how the trend function of the mean of saturated hydraulic conductivity ( μ K s ) and its spatial variability affect the distribution of critical failure surfaces and the probability of slope failure during a period of rainfall. A random field method is used to simulate the spatial variability structure in the numerical analysis of a slope, and a numerical procedure for a probabilistic slope stability analysis based on Monte Carlo simulations is presented, in which K s is modeled as a non-stationary lognormal random field. For a hypothetical weathered soil slope subjected to rainfall, a deterministic analysis and a sequence of probabilistic analyses are conducted using an infinite unsaturated slope model. The results show that these shallow failures are attributed to the reduction of matric suction and the development of positive pore pressure. The probability of slope failure increases with an increase in the variation of the trend component (Δ k ), but the rate of increase levels off at the later stage of rainfall. Ignoring the trend component of μ K s would lead to less conservative estimates of the failure probability. The coefficient of variability has a more significant influence on the distribution of the critical failure surfaces and the probability of failure than does the correlation length of K s . [ABSTRACT FROM AUTHOR]

Many soil parameters are highly variable, especially saturated hydraulic conductivity, which is bound to significantly influence the stability of unsaturated soil slopes that are subjected to rainfall infiltration and redistribution. A random variable model is used to characterize the variability of saturated hydraulic conductivity. Random number sequences of saturated hydraulic conductivity are generated following a lognormal distribution using the Monte Carlo Simulation method. Then the closed form of the limit state function is established, based on the combination of the extension of the Green-Ampt model and the infinite slope stability model. The suggested probabilistic method can calculate the time-dependent failure probability of the slope during a process of rainfall infiltration and redistribution. For a hypothetical slope that is subjected to steady-state rainfall infiltration, a series of parameter analyses are conducted and the results indicate that there exists a critical rainfall duration. At different stages of rainwater infiltration–redistribution, the trends between the failure probability of the soil slope and the coefficient of variation of the saturated hydraulic conductivity have a different form. The coefficient of variation of the saturated hydraulic conductivity does not affect the failure time of the slope that is most likely to occur. This paper figures out why some landslides occur after a rainfall event from the perspective of rainwater redistribution, and the corresponding lag times generally depend on the duration of antecedent rainfall. It is very risky to adopt mean safety factors to assess their stabilities for rainfall-induced landslides when the variability of the hydraulic conductivity is considered. [ABSTRACT FROM AUTHOR]

The frictional capacity of pile–cemented soil interface is similar to the frictional capacity of pile–rock interface as the strength of cemented soil is close to the strength of soft rock. A series of pile–soil interface shear tests were carried out to study the frictional capacity of square pile–cemented soil interface. The shear test results show that the peak skin friction of square pile–cemented soil interface decreased with the increase in the side length of square pile; the failure mode of square pile–cemented soil interface was affected by the cemented soil thickness; the peak skin friction of square pile–cemented soil interface would increase with the roughness of square pile surface when the mean size of coated silica sand reached 0.94 mm, and the peak skin friction increased slightly with the density of coating sand. [ABSTRACT FROM AUTHOR]

The concrete-cored cement mixing (CCM) pile composite foundation is a practical technology for soft soil ground treatment. This paper proposed a theoretical analysis model for the CCM pile composite foundation under embankment in undrained condition which comprehensively considered the interaction between the various components of the CCM pile composite foundation. The working behavior and influencing factors of CCM pile composite foundation under the embankment was also investigated based on the proposed analysis model. The research results showed that: the embankment load was transferred from the outer soil column to the inner soil column. The formation of soil arch effect promoted the concrete core pile to undertake the majority of embankment load, which improved the working behavior of the CCM pile composite foundation under flexible foundation. There was a neutral plane at a certain depth below the ground surface, and the pile shaft above the neutral plane was under negative skin friction, moreover, the vertical stresses of the concrete core pile, cement mixing pile and the soil around the pile all reached the maximum value at the neutral plane. [ABSTRACT FROM AUTHOR]

Building damage induced by the excavation conducted for the three-storey basement of the Kerry Center – a modernised business centre comprising large-scale departmental stores, business offices, apartments and a hotel in Hangzhou, China – was investigated. A method for estimating the building damage level considering the spatial effects of soil deformation around the excavation was also developed. The excavation site is in the Hangzhou urban centre, near to which stands an ancient building known as the Red House. Settlement, horizontal displacement and cracks on the Red House were studied to estimate the actual damage level. Surface settlements around several excavations were analysed to obtain a surface profile along the excavation. The results showed that the profile could be simplified to a parabolic model. A damage criterion based on the average state of strain in the distorted portion of the structure was derived considering the spatial effects of soil deformation. Different damage criteria, including tensile stress, cracks, distortion and horizontal strain, were used to evaluate the damage level of the Red House. The result obtained from the damage criterion presented in this paper agrees well with the actual building damage level. This criterion formed the basis of the preliminary analysis conducted prior to finite-element modelling. [ABSTRACT FROM AUTHOR]

A semi-analytical solution for the groundwater ingress into a lined tunnel in a semi-infinite aquifer is derived based on the conformal mapping technique. The new solution considers the property of the lining, such as the permeability coefficient of the lining as well as the external and internal lining radii. A numerical model is established using the software COMSOL to verify the semi-analytical solution, and a good agreement is found. Parameters including water layer thickness, burial depth of the tunnel, permeability coefficient of the lining and the lining thickness are discussed in detail. This paper explains why the water ingress obtained from early research should be reduced by Heuer’s empirical factor 1/8. Moreover, an optimal burial depth is found when the permeability of the lining is close to the permeability of the aquifer. [ABSTRACT FROM AUTHOR]

Abstract: In this study we developed a tissue engineered bulking agent that consisted of adipose-derived stem cells (ADSCs) and silk fibroin microspheres to treat stress urinary incontinence caused by severe intrinsic sphincter deficiency (ISD). ISD models were established by completely transection of the bilateral pudendal nerve (PNT) and confirmed by the decreased leak-point pressure (LPP) and increased lumen area of urethra. Injection of silk fibroin microspheres could recover LPP and lumen area at 4 weeks but its efficacy disappears at 8, 12 weeks. Moreover, it was exciting to find that tissue engineered bulking agent brought long-term efficacy (at 4, 8, 12 weeks post-injection) on the recovery of LPP and lumen area. Concomitantly with the function, tissue engineered bulking agent treated group also improved the urethral sphincter structure as exhibited by better tissue regeneration. The findings showed that silk fibroin microspheres alone could work effectively in short-term, while tissue engineered bulking agent that combined silk fibroin microspheres with ADSCs exhibited promising long-term efficacy. This study developed a new strategy of tissue engineered bulking agent for future ISD therapy. [Copyright &y& Elsevier]