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Improving the engineering properties of low-strength soft clay in an environmentally friendly way becomes a challenge in coastal areas. Conventional ground treatment techniques for marine clay using cement can cause significant environmental pollution. In this study, the potential use of industrial waste residue-based binder (IWRB), a silicate-based chemical modified by a powdery polymer, as a substitute for Portland cement (PC) is investigated. Collected marine clay was treated with various IWRB-to-PC ratios (0:8, 4:4, 2:6 and 8:0 wt. %) to measure the mechanical properties, through unconfined compression (UC) test and one-dimensional consolidation (ODC) test, and the microstructural and mineralogical characters, through scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetry analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The strength and the deformation of specimens treated with mixed IWRB and PC in a ratio of 1:1 were similar to those improved with PC alone, but the toughness was significantly improved. The microstructural results demonstrated that the cementitious compounds (C–S–H and C–A–S–H) increased significantly in the early curing stage of marine clay treated with IWRB, contributing to the improvement of mechanical properties. It is suggested that IWRB can be an effective substitute for PC to reduce the cost and environmental pollution.

In this paper, the strength, ductility and microstructure behavior of cement-treated silt with polypropylene fiber was studied by a host of experimental studies. The influence of fiber content (the weight of dry soil was 0.75%, 1.0%, 1.25%, 1.5%, 1.75% and 2.0%), curing time (7, 14 and 28 days) and freeze–thaw cycles (3, 6, 9, 15 and 30) on the unconfined compressive strength (UCS), post-peak stress ratio Rps, resilient modulus MR and mass loss ratio Rml of reinforced silt with 12% cement was discussed in detail. Test results indicated that the addition of polypropylene fiber can improve the UCS of reinforced specimen and the optimal fiber content is 1.75%. Under freeze–thaw cycles, the inclusion of clay with fiber content ranging from 0.75 to 2.0% can increase the UCS. The addition of polypropylene fibers can significantly enhance the post-peak stress ratio of the specimens. The mass loss ratio increased with the number of freeze–thaw cycles. The soil specimens free of fiber were completely destroyed after nine freeze–thaw cycles, while the mass loss rate of the soil specimens with fiber were less than 8%. An empirical model was established to predict the peak value of UCS considering the effect of freeze–thaw cycle and fiber content using logarithmic and quadratic polynomial function, respectively. The predicted results are in good agreement with the tested results. The microstructural study shows that the spatial three-dimensional network between fibers and soil particles is conducive to increase the shear strength of the fiber-reinforced silt. The results indicate that the application of polypropylene fiber in silt reinforcement is an effective way to reuse resources.

Excavation following the installation of pile may significantly affect the original behavior of installed piles. To better understand the shaft friction response of existing piles during deep excavation, the principle of pile loading transfer was discussed in this study. Based on the concept of interface normal stress and interface relative displacement, a 5-segment distribution pattern of pile shaft friction was proposed. The varying law and practical calculation model of shaft friction subject to deep excavation was also proposed through numerical analysis. Its feasibility was verified against case histories and this could provide possible reference to pile design incorporating excavation effect.

Surface groove morphology of structure and particle distribution of soil had a significant effect on the surface friction of structure. In order to investigate the interface shear stress-shear displacement curves, interface model and interface shear strength index when normal stress, groove width, and groove angle change, the interface shear tests of standard sand with steel plates are performed using an improved direct shear apparatus. Test results indicate that the peak shear stress increases with normal stress and the intersection angle between groove direction and shear direction. When the angle increases by 45°, the peak shear stress increases range from 4% to 13%. The peak shear stress increases with groove width, for every 1 mm increase in groove width, and the increasing extent of peak shear stress ranges from 4% to 22%, 3% to 13%, and 1% to 6%, respectively. When the groove angle is 45° and 90°, the increasing extent of peak shear stress decreases with groove width, but when the groove angle is 0°, the decrease regularity of peak shear stress increasing extent is not obvious. The hyperbolic model and Gompertz-C model are used to study the shear stress-shear displacement curves of sand-steel interface. The ratio of the interface peak shear stress of the hyperbolic model and Gompertz-C model to that of the shear test ranges from 0.90 to 1.03 and 0.88 to 0.98, respectively. The interface friction angle at the sand-steel interface ranges from 22° to 29°, and the friction angle of the rough interface is larger than that of the smooth interface. The interface friction angle increases with the intersection angle between the groove direction and the shear direction, the largest at 90°, the second at 45°, and the smallest at 0°. Under the same groove angle, the interface friction angle increases with the groove width, for every 1 mm increase in groove width, and the increasing extent of interface friction angle ranges from 4% to 15%, 4% to 7%, and 2% to 3%, respectively. The increasing extent of interface friction angle decreases with groove width, and this change rule is more obvious at the groove angle of 45° and 90° than at 0°.

In this paper, a study on whether the use of polymer would affect the engineering properties of marine clay during and after the consolidation stage was carried out. A polymer, polyacrylamide (PAM)...

The microbial-induced carbonate precipitation (MICP) technique has been increasingly employed for erosion mitigation and stabilization of sandy slopes. Biocementation can improve the streng...

Variations in the dynamic triaxial strength of hybrid basalt–polypropylene fibre-reinforced concrete (HBPRC) with strain rate and confining pressure were investigated, and a dynamic non-linear Mohr–Coulomb (M–C) strength criterion for HBPRC was established. The results showed that the dynamic strength of HBPRC increased non-linearly with the strain rate and confining pressure; however, the strain rate effect decreased with an increase in the confining pressure. The restraint effect of the basalt fibre and polypropylene fibre on the cracks enhanced the strain rate effect of the dynamic strength of concrete. The cohesion of HBPRC increased with the strain rate and confining pressure but decreased with an increase in the amount of fibre monofilaments. However, the internal friction angle showed a reverse trend. The established dynamic non-linear M–C strength criterion reflected the relationship of the dynamic strength of HBPRC with the confining pressure and strain rate, as well as the effect of fibre content on dynamic strength. The less average standard deviation and the tangential relationship between the strength envelope and the Mohr’s circle of stress demonstrated the applicability of the established dynamic non-linear M–C strength criterion.

The performance of steel caisson during and after installation with different penetration velocities in medium dense sand is presented. The applied jacking forces, the amount of formed soil heave a...

An experimental study of the performance of concrete pipe piles during installation under different penetration speeds and static load tests on the piles in sand is presented. The applied jacking f...

Excess pore water pressure is an important parameter that can be used to analyze certain physical characteristics of sediment. In this paper, the excess pore water pressure of subseafloor sediment and its variation with tidal movement was measured following the installation of a wharf in Qingdao, China by using a fiber Bragg grating (FBG) piezometer. The results indicated that this FBG piezometer is effective in the field. The measured variation of excess pore water pressure after installation is largely explained by the dissipation of excess pore water pressure. The dissipation rate can be used to estimate the horizontal consolidation coefficient, which ranged from 1.3×10-6 m2/s to 8.1×10-6 m2/s. The measured values during tidal phases are associated with the variability of tidal pressure on the seafloor and can be used to estimate the compressibility and the permeability of the sediment during tidal movement. The volume compression coefficient estimated from tidal oscillation was approximately 2.0×10-11 Pa-1, which was consistent with the data from the laboratory test. The findings of this paper can provide useful information for in situ investigations of subseafloor sediment.

The interface behavior between a caisson and the surrounding soil plays an important role in the installation of suction caissons as foundations for offshore wind turbines. A series of shear tests were carried out using a modified direct shear apparatus to study the interface shear behavior between sand and concrete. Sand samples with three particle size ranges (0.63–1.25 mm, 1.25–2.5 mm, 2.5–5.0 mm) and concrete plates with different relative roughness were used to explore the influence of the relative roughness parameter (Rn) and mean particle size (D50) on shear behavior. The responses from the pure sand shear test are also discussed for comparison. Test results show that the higher the relative roughness (Rn), the greater the maximum shear stress (τmax) appeared. The interface shear stress was weaker than that of the pure sand test. Furthermore, the interface friction angle (φ) of sand–concrete was closely related to the relative roughness of the concrete surface. Under the same conditions, the interface friction angle (φ) increased with relative roughness due to the effect of sand particles breakage and redistribution. By contrast, the effect of the mean particle size (D50) on the interface friction angle (φ) was less significant. However, for the pure sand shear test, the friction angle (φ′) obtained from the traditional shear test apparently increased with D50, indicating that the friction angle was more affected by D50 in the pure sand test than in the interface shear test.

Fiber Bragg Grating (FBG) technology has emerged as a relatively new sensing technology for engineering applications because of lots of advantages. In this study, a large diameter probe ins...

Melamine manufacturers in Thailand currently produce a substantial amount of melamine products to meet local and international demands. As a result, melamine debris (MD), a waste from melamine manu...

The performance of open-ended piles can be different from that of closed piles due to the effect of soil plugging. This paper presents the results of a large-scale field pile load test conducted on an open-ended pile in clay under static compressive loads. A prestressed high-strength concrete pipe pile with an outer diameter of 400 mm and a wall thickness of 75 mm was instrumented with strain sensors and installed in a marine deposit for static load testing. The measured load-transfer data during pile installation and the pile load test results are reported and analysed. The data show that the pile was in a partially plugged condition during jacking and behaved in a fully plugged mode in the static load test. The measured ultimate shaft resistance and total resistance of the test pile were 659 and 1180 kN, respectively, which were smaller than the values calculated using a previously proposed method. The back-calculated α and β values (as used in the α and β methods) for axial pile capacity in marine deposits were 0·42 and 0·56, respectively.

A model test program for studying soil stratum failure and pore pressure variation during tetrahydrofuran (THF) hydrate dissociation considering the effects of heating and drainage conditions is pr...

To effectively characterise the dynamic mechanical properties of basalt fibre-reinforced coral aggregate concrete (BFRCAC) under confining pressure, a dynamic constitutive model of BFRCAC is presented through characterising the basalt fibre reinforcement by measuring the variation in elastic modulus and the mechanical damage by measuring the fracture probability of micro-crack propagation. The dynamic mechanical properties of BFRCAC under different confining pressures were investigated using a split Hopkinson pressure bar device with active confining pressure. A comparison of the theoretical results and experimental results indicates the good validity of the dynamic constitutive model. Analysis of damage development reveals that both strain rate and confining pressure have delayed effects on damage development. The addition of basalt fibre at an appropriate content reinforces the BFRCAC; consequently, the total damage is less than the mechanical damage in the early stage of deformation. As the deformation progresses, basalt fibre is gradually destroyed and its reinforcement effect gradually disappears, causing the total damage to gradually approach the mechanical damage. The bridging effect of basalt fibre helps restrain crack propagation ; this not only slows the rate of damage in BFRCAC but also improves the confining pressure effect and strain rate effect of damage development.

Suction bucket foundation is a typical type for offshore turbines. Scour caused by wave and current can reduce the stability of foundation and then endanger the whole structure. This paper details ...

In geotechnical engineering seepage of diaphragm walls is an important issue which may cause engineering disasters. It is therefore of great significance to develop reliable monitoring technology to monitor the leakage. The purpose of this study is to explore the application of a distributed optical fiber temperature measurement system in leakage monitoring of underground diaphragm walls using 1 g model tests. The principles of seepage monitoring based on distributed optical fiber temperature measurement technology are introduced. Fiber with heating cable was laid along the wall to control seepage flow at different speeds. The temperature rise of the fiber during seepage was also recorded under different heating power conditions. In particular the effect of single variables (seepage velocity and heating power) on the temperature rise of optical fibers was discussed. Test results indicated that the temperature difference between the seepage and non-seepage parts of diaphragm wall can be monitored well using fiber-optic external heating cable. Higher heating power also can improve the resolution of fiber-optic seepage. The seepage velocity had a linear relationship with the final stable temperature after heating, and the linear correlation coefficient increases with the increase of heating power. The stable temperature decreased with the increase of flow velocity. The findings provide a basis for quantitative measurement and precise location of seepage velocity of diaphragm walls.

Fiber Bragg grating (FBG) sensors emerged as a relatively new strain-sensing technology for civil engineering applications. This study presents a field test to assess the feasibility of FBG...

The behavior of open-ended pipe piles is different from that of closed-ended pipe piles due to the soil plugging effect. In this study, a series of field tests were conducted to investigate the behavior of open-ended prestressed high-strength concrete (PHC) pipe piles installed into clay. Two open-ended PHC pipe piles were instrumented with Fiber Bragg Grating (FBG) sensors and jacked into clay for subsequent static loading tests. Soil plug length of the test piles was continuously measured during installation, allowing for calculation of the incremental filling ratio. The recorded data in static loading test were reported and analyzed. The distribution of residual forces after installation and the effect on the bearing capacity were also discussed in detail. The test piles were observed to be in partially plugged condition during installation. The measured ultimate shaft resistance and total resistance of the test piles were 639 and 1180 kN, respectively. The residual forces locked in the test piles after installation significantly affected the evaluation of the axial forces, and thus the shaft and end resistances. It tended to underestimate the end resistances and overestimate the shaft resistances if the residual forces were not considered in the loading test. However, the residual forces did not affect the total bearing capacity of open-ended PHC pipe piles in this study.

The shear behavior of sand-steel interface plays an important role in the performance of steel pipe piles that support marine structures. In this study, the effects of surface roughness (from rough surface to smooth surface) and mean particle size on mobilized sand-steel interface friction were investigated by direct shear tests. Three types of calcareous sand with different particle sizes and three steel plates with different surface roughness were employed in the experimental program. Results indicate that the surface roughness of steel plate has a significant effect on the shear behavior between calcareous sand and steel. The peak shear strength increases with the surface roughness, and the interface friction angle reaches 90% of the internal friction angle of calcareous sand with various particle size. Moreover, the interface friction angle of calcareous sand is higher than that of siliceous sand, which is due to the effect of soil densification and particle breakage during the specimen preparation of calcareous sand.

In this study, the dynamic compressive behaviour of concrete reinforced with hybrid basalt-polypropylene fibres (HBPRC) and different matrix strengths was investigated using a split Hopkinson pressure bar. The results indicated that the differences between the highest dynamic strength and the dynamic strength of the reference concrete for each matrix strength grade increased from 6.63 MPa, 3.77 MPa, and 4.80 MPa under the minimum strain rates to 7.16 MPa, 9.04 MPa, and 12.08 MPa under the maximum strain rates. The strain rate effect of dynamic compressive strength of HBPRC was increased by increasing the volume of hybrid basalt fibre (BF) and polypropylene fibre (PF) from 0.1% to 0.2%, but was decreased with increasing matrix strength. The toughness was increased with increasing strain rate, hybrid BF and PF volume, and matrix strength. A microscopic test indicated that an increase in the matrix strength and strain rate exhibited a similar impact on the damage patterns of BF and PF. The primary effect of BF on the dynamic mechanical properties of HBPRC was to increase the strength and that of the PF was to improve the energy dissipation. A dynamic damage constitutive model for HBPRC was established based on the continuum media and statistical damage theories, and its validity was verified.

The microbial induced carbonate precipitation (MICP) technique has been increasingly employed for ground improvement and fracture sealing, as well as for erosion mitigation and stabilization of sandy slopes. However, there is a lack of an effective assessment method to estimate the erosion resistance of biocemented sandy slope under wave actions. In this study, a series of bench-scale flume erosion tests was conducted on sandy slopes with and without MICP treatment under waves to quantitatively investigate the erosion resistance. Variables, including the MICP treatment cycle(0 ~ 4 cycles) and the slope angle (10°, 20°, and 35°), were explicitly considered. Penetration tests were conducted to measure the strength of biocemented sand at the slope surface. The calcite mass was calculated using theacid washing method to evaluate the level of cementation. Results show that the erosion resistance follows a nonlinear relationship with the penetration resistance. A fitting calculation was therefore carried out to evaluate the erosion process of MICP-treated sandy slope based on the results oferosion and penetration tests for use to assess the slope stability. A microstructure study also shows that there was interlocking cementation produced between sand particles in the sandy slope after MICP treatment,whichcontributed to the increase in erosion resistance ofsand.

A special case of geosynthetic tubes is the geosynthetic mattress characterized by its larger width-to-height ratio and higher lateral-force-resisting capacity. When the geosynthetic mattresses are adopted for dike or breakwater construction in coastal engineering projects, they are often laid on deformable foundation soil. The induced ground settlement will influence the cross-sections and tensile forces of the geosynthetic mattresses. Two analytical methods, called the Winkler foundation method and the e–log p method, are proposed in this paper to analyze the geosynthetic mattresses resting on deformable foundation soil. For the Winkler foundation method, the subgrade soil is assumed as a Winkler elastic foundation represented by the modulus of subgrade reaction, Kf. For the e–log p method, the 1D consolidation relationship (e–log p curve) is adopted to describe the behavior of the subgrade soil within which the distribution of vertical surcharge is calculated using Boussinesq equation. The nume...

A large-scale field testing program for the study of residual forces in pre-stressed high-strength concrete (PHC) pipe piles is presented in this paper. Five open-ended PHC pipe piles with 13 or 18 m in embedded length were installed and used for static loading tests at a building site in Hangzhou, China. All the piles were instrumented with fiber Bragg grating (FBG) strain gauges. The residual forces in these piles were recorded during and after installation. The measured load transfer data along a pile during the static loading tests are reported. The effect of the residual force on the interpretation of the load transfer behavior is discussed. The field data show that residual force along the installed pile increases approximately exponentially to the neutral plane and then reduces towards the toe. The residual force decreases with time to a stable value after pile jacking due to the secondary interaction between the pile and the disturbed soil around the pile and other factors. The large residual forces along the PHC pipe piles significantly affect the evaluation of the pile load distributions, and thus the shaft and toe resistances. The conventional bearing capacity theory tends to overestimate the shaft resistance at positions above the neutral plane and underestimate the shaft resistance at positions below the neutral plane, and the toe resistance for an open-ended PHC pipe piles founded in stratified soils.

This paper presents the results of static compression load tests performed on long rock-socked bored piles installed in stratified soils. Three bored piles with 34 m in embedded length were instrumented in order to separate the shaft and base resistance, and to allow the determination of the distribution of shaft resistance along the pile shaft. Conventional methods of estimating shaft resistance were assessed. It was found that more than 78% of the shaft resistance was provided by shaft friction at the end of tests. The base resistance has not been fully mobilized in the test. The recommendations of Chinese technical code (JG94-2008) to estimate the shaft resistance were more conservative for long rock-socketed bored piles. Empirical correlations to estimate the shaft resistance are limited due to different geological conditions. The methods which incorporated parameters directly interpreted from standard penetration test (SPT) results provided the most consistent estimates.

Large-scale field tests were conducted to study set-up effect in open-ended prestressed high-strength concrete pipe piles jacked into stratified soil. Four open-ended prestressed high-strength concrete pipe piles with 13 and 18 m in embedment depth were fully instrumented with fiber Bragg grating sensors and installed. Several restrike dynamic tests were performed on each test pile, with the time interval from 21.5 to 284 hours after installation. Static loading tests (SLTs) were later performed on each test pile at 408 hours after installation to substantiate the dynamic tests. Changes with time in pile bearing capacity and in the shaft and toe resistances were studied based on the results of the pile tests. The development of shaft resistance set-up in different layers was studied in particular. It was found that set-up effect in the shaft resistance is significant and the toe resistance increment was minor. The overall set-up factor of total bearing capacity was found to range from 0.09 to 0.53...

A semi-analytical methodology is developed for the transient response of FGM annular sector plate with arbitrary circular boundary conditions. The state space method, differential quadrature method and the numerical inversion method of Laplace transform are integrated into this methodology. The FGM annular sector plate is simply supported at the radial edges. At the circular edges, four kinds of boundary conditions are considered in this paper: Clamped–Clamped, Clamped–Simply supported, Clamped–Free and Simply supported–Simply supported. A comparison of the results generated by the present and finite element method is carried out. It shows that the results of the present and the finite element method always agree with each other excellently, regardless of which boundary condition, load and geometry are employed. The present method is further validated by comparing the fundamental frequency parameters with those in the literature. Moreover, convergence studies for different numbers of sampling points along the radial direction and layer numbers along the thickness direction are performed. It is found that this methodology has fast convergence rate. The effects of the boundary conditions, the functionally graded index, and the thickness on the plate response are also investigated. The results obtained in this paper can serve as benchmark data in further research.

In recent years, roads in Singapore have had to be constructed on reclaimed land using marine clay as fill materials. Improving the engineering properties of the high water content, soft clayey soil in the reclaimed land in a cost-effective way before road construction becomes a challenge. It is expensive to treat high water content soil using cement because the amount of cement required would be excessive. In this paper, a study on the potential use of a waste-based binder as a substitute for portland cement for the improvement of high water content soil is presented. A series of laboratory tests were carried out to assess the undrained shear strength of binder-treated marine clay compared with the use of cement. The test results indicated that for soil with a high initial water content, the use of waste-based binder could shorten the curing period by about 20% while achieving the same unconfined compressive strength or increase the undrained shear strength at 14 or 28 days by 20 to 50% compared with the marine clay treated with cement of the same dosage. The aging effect of the waste-based binder was stronger. A microstructural study also shows that there are interlocking matrixes produced between soil particles in the binder-treated soil that contributes toward the increase in shear strength in the soil.

A series of large-scale direct shear tests for the study of interface behavior between concrete piles and silty clay are presented in this paper. Concrete platform was used to model concrete pile in the test. The shear forces and displacements were measured. The distribution of soil partials of silty clay before and after shearing was also compared using single-lens-reflex digital camera. Test results show that the shear forces between concrete platform and soil samples are closely related to the vertical loading implemented on the soil sample and the interval times. The larger the vertical loading, the larger the shear forces. With the increase of interval times, the shear forces between concrete platform and soil samples gradually increased. It is also indicated that the vertical loading has little effect on the time effect of shear forces. As the interval time lasts, the particles of soil samples gradually upheaved and the deformation area increased. Based on the predicted three-phase model with respect to the log of time, the time points of 1.0 day and 109 days can be taken as the first and second time points respectively in this test.

A good understanding of the mechanical behavior of functionally graded material (FGM) cylindrical shells is necessary for designers and researchers. However, the 3D transient response of FGM cylindrical shells under various boundary conditions has not yet been analyzed. In this paper, the problem is addressed by proposing an approach integrating the state space method, differential quadrature method, and Durbina’s numerical inversion method of Laplace transform. The laminate model is used to obtain the transient solution in the radial direction. At the edges, four kinds of boundary conditions are considered: Clamped-Clamped, Clamped-Simply supported, Clamped-Free, and Simply supported-Simply supported. The results of the proposed method and finite element (FE) method agree with each other excellently. Convergence studies show that the proposed method has a fast convergence rate. The natural frequencies obtained by the proposed method, experiment, and other theoretical methods are in close agreement with each other. The effects of the load frequency and duration, length/outer radius ratio, and the (outer radius-inner radius)/outer radius ratio on the transient response of FGM shells are investigated. Two laws of variation of material properties along the radial direction are considered: the first has material properties varying according to an exponential law along the radial direction, while the second has material properties varying according to a power law. The effect of a functionally graded index on the transient response of FGM shells is investigated in both cases. The results obtained in this paper can serve as benchmark data for further research.

Anchors are often used as anti-floating reinforcements in civil engineering structures. However, conventional steel bars present disadvantages concerning corrosion and poor adaptability to aggressive environments. Glass fiber-reinforced polymer (GFRP) components could provide a solution to these problems. In this paper the feasibility of GFRP anti-floating anchors is evaluated. Four full scale pullout tests were performed in moderately decomposed granite (MDG). Bare Fiber Bragg grating (FBG) sensors were embedded into the specimens during the pultrusion process to monitor the stress–strain distribution along their lengths. Based on the results the behavior of the anchors was assessed, including the relationships between the pullout force and the head displacement, the axial strain along anchors and the shear stress at the GFRP-grout interface. The stress distribution of anchors showing interlaminar shear failure was then analyzed based on a maximum shear stress criterion. It was proved that the load transfer mechanism of GFRP and steel anti-floating anchors differs significantly. GFRP anti-floating anchors reach failure due to interlaminar shear failure, while conventional steel anchors generally fail as a result of shear at the grout–soil interface. The test results also showed that the embedded FBG technique is reliable for monitoring the stress–strain state of an anisotropic material.

In recent years, marine clay has been used as a fill material for land reclamation in Singapore. The technique adopted to improve the strength properties of marine clay plays a critical role in land reclamation projects. In this study, a series of laboratory tests have been conducted to determine the potential to use a chemical binder to stabilize marine clay in Singapore. Test results show that the chemical binder could offer shorter curing period and higher strength. With the same dosage, the unconfined compressive strength of chemical binder treated marine clay is about 1.2-1.4 times of cement treated marine clay at 14 and 28 curing days. At 14 curing days, the strength of chemical binder treated marine clay can reach 80% of the maximum value. This proves that 14 curing days is enough to make the chemical binder treated marine clay obtain sufficient strength. Furthermore, chemical binder treated marine clay has no slaking behaviour in underwater environmental. This also indicated chemical binder treated marine clay has a good cohesiveness.

Glass fiber-reinforced polymer (GFRP) bolts have been widely used in some applications of grouted anchors because of the advantages of better resistance to corrosion, high strength-to-weight ratio, low electromagnetic properties, and so on. This study presents a field test to assess the feasibility of fiber Bragg grating (FBG) sensors in monitoring the stress profile of GFRP anchors during pulling test. Two GFRP anchors were fully instrumented with FBG sensors and then installed into the ground using a drilling and grouting method. To measure the stress profile along test anchors, seven bare FBG sensors were arranged in a single optical fiber and then embedded in the middle of GFRP bolts in the process of extrusion molding. The procedure for embedding bare FBG sensors into GFRP bolts is introduced first. Then, the axial forces and shear stresses that were calculated from the measurements of the FBG sensors are discussed. The field test results indicate that the embedded FBG technology was feasible to monitor the stress state of GFRP anchors during pulling.

An experimental study of the formation of the soil heave plug inside a concrete caisson during installation in clay under suction is presented. The soil heave plug, the amount of caisson penetration and the vacuum pressure applied were measured during the model tests. The results show that the soil heave plug can completely fill in the cavity and prevent the caisson from penetrating further. The soil heave plug is affected by the geometry of the caisson. The higher the consolidation stress or the stiffer the soils, the higher is the suction pressure required, and a higher suction will in turn induce a greater soil heave plug. The m value, defined as the ratio of the volume of the soil heave plug to that of the penetrated caisson skirt wall, is adopted to evaluate the soil heave plug. The relationship between the m value and the undrained shear strength of the soil can be used to estimate the amount of soil heave plug and the caisson penetration for a concrete caisson with a wall thickness to external diameter ratio of 5% in normally consolidated clay conditions. NRF (Natl Research Foundation, S’pore) Published version

This paper firstly expounds the scope and principle of riprapping for sludge extrusion, and then details of quality control standard of the construction technology and process are described according to the engineering practice. The points of subsidence, surrounding upheaval, deep horizontal displacement, and pore water pressure are also monitored respectively set in hydraulic fill mud area. The monitoring data are analyzed for conclusion to explore the feasibility and existing problems of riprapping for sludge extrusion in this experiment.

As the most important feature of jacked open-ended concrete pipe piles, shear zone has fluence of crucial importance during installing and after penetration. This study conducted a field test in silt deposit to observe the physical phenomenon of shear zone after installation and investigated soil parameter differences from undisturbed soil through laboratory tests. Direct observation on shear zone reveals that the boundary between shear zone and in situ soil is evident. The average soil thickness in the shear zone falls between 6 and 30 mm, which are closely related to natural water content and void ratio in different layers. Laboratory tests on the shear zone show evident compaction during installation, and the soil parameters in the shear zone are sensitive to the jacking installation procedure. Some soil parameters decrease, whereas others increase because of excess pore water dissipating after installation. The extent of the shear zone is helpful in understanding interface friction on pretensi...

Pressured multi-branch bored pile is a new pile on the basis of squeezed branch reaming pile improved, it is a new pile technology focus on many advantages of the static pile, driven cast-in-place pile, belled pile and multi-branch bored pile. Pressured multi-branch bored pile has high bearing capacity, small settlement, cost-effective advantages of better. Numerical simulation of pressured double-branch pile on the vertical compression with ANSYS finite element analysis software obtained the alternate variation of the lateral friction and tip resistance of pile under the vertical load. Many branch of pile constitute multi-pivot friction and end-bearing pile, the bearing branch bear mainly bear vertical load, above branch force greater than the following branch. It is proposed recommended value about the vertical critical spacing of branch and the level spacing of pressured branch pile.