
Kai YaoShandong University | SDU · School of Qilu Transportation
Kai Yao
Ph.D. (National University of Singapore)
Humboldt Fellowship for Experienced Researcher
About
88
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1,748
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Introduction
Skills and Expertise
Additional affiliations
September 2018 - February 2019
March 2019 - October 2020
January 2017 - August 2018
Education
January 2013 - January 2017
September 2010 - June 2013
September 2006 - June 2010
Publications
Publications (88)
Landslides significantly threaten lives and infrastructure, especially in seismically active regions. This study conducts a probabilistic analysis of seismic landslide runout behavior, leveraging a large-deformation finite-element (LDFE) model that accounts for the three-dimensional (3D) spatial variability and cross-correlation in soil strength-a...
The Deep Cement Mixing Integrated Drilling, Mixing and Jetting (DMJ) method represents a novel approach to the construction of slurry piles in the Yellow River Floodplain, offering the potential to enhance the quality of these structures. In order to investigate the pile strength and its distribution characteristics under different conditions, an u...
The Deep Cement Mixing Integrated Drilling, Mixing and Jetting (DMJ) technique has been developed through the installation of high-pressure spray holes at the mixing blades, with the objective of enhancing the bearing capacity of deep-mixed piles in the Yellow River floodplain. In order to enhance the bearing capacity of the foundation, variable-mo...
Submarine pipeline has been utilized more and more widely in offshore oil and gas transportation engineering. Given that these pipelines frequently subject horizontal loading during operation, thus precise predicting their horizontal bearing capacity is essential. However, most previous studies employ deterministic analysis without considering soil...
Jia Liu Yi Xue Huimin Wang- [...]
Kai Yao
Comprehending the intricate mechanics and fracture characteristics of shale holds significant importance in the realm of controlling the reconstruction of shale gas reservoirs. It is noteworthy that shale typically exhibits a distinctive bedding structure which sets it apart from other geological formations. Previously, single-mode cracks in shale...
This paper presents a numerical study to model the thermal-induced pipeline buckling-soil interaction as a demonstration of the feasibility of modeling global buckling using an effective stress remeshing and interpolation technique with a small strain (RITSS) approach in 3D. The numerical results are compared with a previously published large-scale...
In the offshore fields, helical piles are increasingly deemed to constitute suitable tools for anchoring floating structures and wind turbines. A large number of studies have been published to explore the installation torque–capacity correlation, and most of them are conducted in a deterministic manner. However, natural soils are inherently spatial...
The importance of accurate estimation of elastic stiffness coefficients of suction caisson has been already highlighted in previous works. Nonetheless, studies related to the spatial non-uniformity of the clayey seabed are somewhat limited, and current theoretical solutions are usually established using deterministic soil properties, overlooking th...
I am delighted to introduce this September issue of Ground Improvement to you on behalf of the editorial panel. Recently, soil mechanism problems have held researchers' attention worldwide, and as such, there are a total of six papers in this issue on the study of soil mechanisms and characteristics. Following are synopses of these papers. The firs...
Given the wide application of lime stabilized loess in road base and subbase, subgrade, building foundations and slopes, a set of generalized and accurate mechanical estimation models of lime stabilized loess is essential for quality control. In this research, three modified models were proposed to capture the effects of lime content and compactnes...
This issue of Geotechnical Engineering (volume 176, issue 3) includes nine papers discussing a wide range of topics. One paper revisits the standard relationship between plasticity index and linear shrinkage; another analyses the reinforcement effect on the end soil of rectangular pipe jacking; one paper is on the design life of clay cut slopes; an...
Highway widening is an important way to improve the existing expressway capacity and promote the development of transportation systems. The differential settlement between the old and new subgrade is the key factor to evaluate whether it is necessary to carry out ground improvement for the new foundation, which will cause longitudinal pavement crac...
Silt in the Yellow River alluvial plain is widely spread, but its uniform particle size and high roundness make it unsuitable as a subgrade filling material, while titanium gypsum (TG) is an industrial solid waste in Shandong Province, not only occupying land resources but also causing water and air pollution. In order to improve the engineering pe...
This paper examines the effect of dynamic compaction by multi-point tamping on the densification of sandy soil between adjacent impact points. First, by using a three-dimensional finite element analysis, tamping was modelled using drop weight with prescribed impact velocity. The numerical model was then validated with centrifuge model test results...
Technical advances in horizontal drilling and hydraulic fracturing have significantly improved commercial shale gas development. However, current shale gas development has encountered the challenge of sustainability. Therefore, there is an urgent need to develop new technologies for shale gas production. Microwave irradiation can be used as an auxi...
We have reached the October issue of Volume 175 of Geotechnical Engineering. As soil mechanism problems have researchers' attention worldwide, the fifth issue of this year has eight papers discussing the chemical stabilisation of soft soils, landslides, river levee failures and the generalised limit equilibrium approach. In addition, we have papers...
Road infrastructure is often built above the groundwater table. The materials used are usually compacted and thus generally remain under unsaturated conditions throughout their service life. This paper presents experimental results that highlight the influence of matric suction on the resilient modulus (M R) and California bearing ratio (CBR) of a...
Yanbin Jiang Kai Yao Sin- [...]
Yu Rong
This paper aims to present an integrated analytical model for geosynthetic-reinforced and pile-supported embankments (GRPSEs) by rationally combining the reinforced embankment, the pile-embedded soft soil foundation, the stress adjustment region, and the equal settlement region of the substratum. The embankment geometry boundary is considered for c...
Helical piles are one promising foundation option in offshore industries to support wind turbines and floating structures. During service, the helical piles are subjected to combined loading originating from the superstructure and environmental factors. For the inclined pullout capacity of hel-ical piles, several studies focused on the influence of...
This paper presents a numerical study of dynamic compaction (DC) on ground improvement in foundation with a high groundwater table, based on a dynamic fluid–solid coupled finite element method with a cap model. Firstly, an analysis of dry ground was carried out to evaluate the effective improvement range, with the proposal of a normalized formula c...
The August 2022 issue of Ground Improvement has been reached. As soil mechanism problems have the worldwide researchers' attention, 5 papers make up this this third issue, discussing sulfonated oil (SO) effects on expansive soil properties , the improvement methods performance of tunnel excavation , and the performance of unpaved roads reinforced w...
The behavior of buried offshore pipelines subjected to upheaval buckling has attracted much attention in recent years. Numerous researchers have made great efforts to investigate the influence of different soil cover depth ratios, soil strengths and pipe-soil interfaces on failure mechanisms and bearing capacities during pipeline uplift. However, a...
Effective recognition of the representative volume element (RVE) of non-homogeneous materials is vital and has been applied in various fields. However, most recognition methods are based on computer-simulated images, and little attention has been paid to real non-homogeneous materials with complex structures. To solve this problem, this study propo...
The bedding plane with the special structural characteristics may have a significant influence on the cracking behavior induced by stress wave in bedded shale. This study proposes a novel phase-field model to predict the dynamic crack propagation path in bedded shale. The bedding plane is assumed to be the thin elastic layer with the certain thickn...
The unidirectional migration of electroosmotic flow under direct current electric field has remained an issue of previous studies such as seriously uneven strength and difficult drainage collecting, which primarily limited the practical engineering applications of electroosmosis method. Innovative cyclic and progressive electroosmosis method (CPE)...
Ballastless tracks are widely used to provide high rail smoothness in high-speed railways. However, the differential settlement inevitably develops in the subgrade soil, which poses a great threat to the track performance and riding quality via the train-rail dynamic interaction. Since the ballastless tracks are extremely difficult to repair during...
Two sites with different groundwater tables (3 m and 2 m, respectively) were chosen for the in situ test to assess the variation of excess pore pressure during dynamic compaction. Numerical analysis by FLAC3D was also performed to examine the liquefaction potential of silty ground, considering the effect of the water table and tamping energy. Exper...
To evaluate the quality of the subgrade reinforcement by dynamic compaction (DC), a dynamic finite element model was established based on the soil cap yield hardening model. A subroutine was performed to simulate the parameters (e.g., modulus of soil) changing with drop numbers. The numerical results agreed well with the results of the field test,...
Electrokinetic remediation is often developed for heavy metal–contaminated soils but shows limitations for the drainage and volume reduction of the soil, and electrolyte is difficult to apply in in situ practical engineering. Innovative cyclic and progressive electrokinetic remediation and electroosmotic consolidation method (CP-ERC) were proposed...
With the massive exploitation and utilization of no-renewable natural resources, good-quality road building materials has been becoming scare and it is an urgent demand to explore and develop alternatives. This study investigated feasible approaches of using red mud as a filler substitute to replace limestone powder in asphalt mixtures. In order to...
In situ soil properties exhibit spatial variability, which is often described using a three-dimensional (3D) random field. With site investigations, soil properties at some specific locations are available. The corresponding data can be incorporated by a conditional random field to update the uncertainty parameters so that a more realistic or refin...
This paper examines the effectiveness of using varying proportion (2%, 4% and 6% by dry weight of soil) of a
newly formulated biomass silica soil stabiliser (BSS) on tropical lateritic clay which has deleterious effects on
construction materials due to its high amounts of SiO2 and Fe2O3. A series of laboratory experiment testing
methods: i.e. parti...
The model uncertainty is explored for two ISO methods to estimate the peak penetration resistance in an offshore spudcan foundation punch-through incident. The model factor, defined as the ratio of measured resistance to calculated resistance, is introduced in the characterisation of the model uncertainty. Model uncertainty of a coupled Eulerian–La...
The stability assessment of a soil embankment in the flooding season has attracted increasing attention in recent years. The current study performs a coupled hydraulic-mechanical analysis of an embankment subjected to water level fluctuation. The coefficient of permeability of embankment soils is represented by a uniform random field with upper and...
Piles are usually installed in both onshore and offshore sites to transit the structural loads through soft or loose soil layers to competent soil strata. Although the installation of a single pile is usually considered to be undrained, consolidation may take place during the installations of multiple piles, especially in the pauses between neighbo...
This paper is aimed to investigate the bond performance of mortar with magnesium phosphate cement (MPC) as a novel-type repair material. This is achieved by mixing ferroaluminate cement (FAC) with MPC to prepare composite cement (MPC-FAC). Under standard and water curing conditions, the properties of MPC-FAC composite including setting time, ph, co...
Dynamic compaction (DC) is one of the most popular methods for ground improvement. To solve the problem of the factors affecting the sandy soil improvement effect and estimate the effective improvement range under DC, the influences of drop number, drop energy, tamping distance, tamper radius, and drop momentum on the relative degree of improvement...
Water/cement (w/c) ratio is a critical parameter for the wet deep mixing method. In Singapore, a relatively high w/c ratio of 1.0–1.2 is typically used , which may reduce the performance of the cement-stabilized clay. Hence, effect of w/c ratios on geotechnical properties of cement-stabilized clay is investigated. The results indicate that as the w...
Nanomaterials for asphalt modification and incorporating nanoparticles into asphalt mixtures to deal with road failure have gained popularity recently. Researchers have reported the improved performance of asphalt modified by carbon nanotubes (CNTs), but the cost is very high with the relatively high CNTs content. This work studied the composites m...
Because of the scarcity of irreplaceable natural resources and environmental pollution of demolished asphalt pavement, circular utilization of Reclaimed Asphalt Pavement (RAP) to prepare recycled asphalt pavement mixtures was promoted. To restore properties of the aged bituminous binder in RAP, rejuvenators designed with diverse viscosity levels an...
Vacuum preloading combined with electroosmosis (VE) has a good drainage effect, but electric vertical drains (EVDs) as the drainage plate and electrode will cause the offset of water flow near the anode. Therefore, there is an alternate time for the optimal use of the two methods. In this paper, some macroscopic indexes were monitored through labor...
Jia Liu Yi Xue Qi Zhang- [...]
Songhe Wang
Thermal stimulation for shale gas reservoirs may cause water to evaporate, accelerate desorption of adsorbed gas and induce micro-scale cracking in shale matrix, which will increase shale gas productivity. However, few researches have been focused on the thermal micro-cracking behavior of shale matrix. In this paper, a novel energy functional consi...
Low improvement ratio soil-cement columns adopted in ground improvement are cost-effective with less environmental impact. However, the settlement mechanism of the reinforced area has not been clearly established, and the traditional settlement estimation formula only treats the reinforced area as an elastic block. Settlement of the reinforced area...
A fully coupled thermo-hydro-mechanical model in multiphase shale gas reservoirs is first developed and is then validated with analytical solutions and experimental result. Subsequently, the coupling responses are investigated to addressing mechanisms of gas recovery enhancement. Finally, a series of parameter sensitivity analyses are implemented t...
This study presents the results of a systematic investigation on enhancing the shear strength and bearing capacity of subgrade fill by blending the completely weathered phyllite (CWP) with locally won red clay at varying blending ratios. Many CWP soil samples were prepared at varying bended ratios for carrying out a compaction test, micro-penetrati...
Jia Liu Xin Liang Yi Xue- [...]
Dou Fa Kai
The physical, mechanical, and hydraulic properties of shales with continuous bedding plane vary with bedding orientation significantly. Thus, understanding and predicting crack initiation and propagation in hydraulic fracturing of bedded shale are crucial in terms of reservoir reconstruction. In this paper, a hybrid phase‐field method is proposed t...
This paper proposes a conceptual framework for describing the small-strain shear modulus (G max) of cement-treated clay based on the results of parametric studies covering the influence of mix ratio, curing time, void ratio, stress state, overconsolidation, and yielding on the small-strain shear modulus of cement-treated soft clay. The small-strain...
In this paper, three sets of laboratory tests were conducted on high-food-waste-content (HFWC-), no-food-waste-content (NFWC-) and decomposed (D-) MSWs to characterize their compression behaviors. The immediate compression ratios C 0 c were 0.30, 0.23 and 0.18 for HFWC-MSW, NFWC-MSW and D-MSW respectively, and tended to increase with the increasing...
Model tests were conducted for sand foundations reinforced by geocells, waste tire chips, and geocell–tire chips. Three factors related to the foundation performance are mainly examined in the current study: the embedded depth of the first layer of the geocells, the vertical spacing of geocell layers, and the content of waste tire chips. The experi...
In this paper, a hybrid phase field modelling is implemented to investigate the fracture behavior of bedded shale. The model first is compared with the anisotropic phase field model and is validated by a benchmark test. Subsequently, three-point-bending tests are conducted on bedded shale and the corresponding simulations are done by hybrid phase f...
This study explores the mechanism of the undrained response of tunnelling through spatially variable improved soil. It is found that spatial variability produces a more realistic failure mechanism compared to that produced by the conventional homogeneous assumption. The overall failure of the improved ring through which the tunnel passes occurs whe...
Wei Wang Yuan Li Kai Yao- [...]
Chen Zhang
The characteristics of nanometer magnesium oxide (nano-MgO) admixed cement in the treatment of clay were studied in direct shear tests. The chemical resistance of the admixed clay cement was investigated by soaking specimens in sulfuric acid solution. Various contents of nano-MgO (from 5‰ to 20‰) were mixed with ordinary Portland cement (OPC) and i...
A certain amount of ferroaluminate cement (FAC) was substituted for MgO during the magnesium phosphate cement (MPC) preparation to obtain the MPC–FAC composite cement. The influence of FAC on the strength, water resistance, pH, and setting time of MPC–FAC composite cement were examined. The microstructure and chemical composition were also analyzed...
This study aimed to investigate the feasibility of using lime–slag stabilized loess as base-course material by assessing its unconfined compressive strength (UCS). Loess stabilized with various mix ratios were compacted and cured to three, five, seven, and 28 days, respectively, for further strength tests. The effects of binder content, lime-to-sla...
Lime stabilization has been widely used in pavement subbases and ground improvement, but the investigation of the mechanical properties and the microstructure of lime stabilized loess is still insufficient. In this study, the effects of lime content, porosity and curing time on the strength development of lime stabilized loess were investigated thr...
Based on the horizontal slice method (HSM) and assuming a log spiral slip surface, a method to analyze the stability of a reinforced retaining wall under seismic loads was established in this study by calculating the tensile force of the reinforcement. A parametric study was conducted on the normalized tensile force of the reinforcement, and it was...
Evaluation of the strength of cement-treated clay with a broad range of mix ratios and curing periods was conducted using unconfined compression tests (UCTs). The influence of cement content, total water content, and curing period on the unconfined compressive strength of cemented clay are investigated. It is found that, at constant total water con...
Kai Yao Wei Wang Na Li- [...]
Linxia Wang
The effectiveness of nano-MgO in strength properties and microstructure characteristics of cement stabilized soft soil were analyzed in this study. Sulfuric acid attack was also taken into account, and the effects nano-MgO content and sulfuric acid concentration were mainly addressed. Based on a series of unconfined compression tests, it shows that...
With the increasing popularity of stabilizing soft soils by a cementitious binder, accurate strength prediction of cemented clay with curing period is essential for quality control. In this study, a generalized hyperbolic was proposed to overcome the shortcomings of traditional logarithmic function with regard to both short-term and long-term predi...
A series of direct shear tests were performed on cement-admixed silty clay to investigate the effect of cement content and nano-magnesia (MgO) on its shear strength properties. For each normal stress, shear strength increased with cement content. However, an obvious increment in shear strength was achieved when the cement content was adjusted from...
Wei Wang Chen Zhang Na Li- [...]
Kai Yao
In this study, the mechanical behaviour of nano magnesia–cement-reinforced seashore soft soil (NmC3S) was evaluated and characterised by the direct-shear testing of seashore soft soil (3S), cement reinforced seashore soft soil (C3S) and NmC3S. The comparison among these three types of soils indicates that NmC3S has greater shear strength and deform...
Monitoring the settlement of high-fill subgrade plays a significant role in maintaining the service quality of highways. To investigate the postconstruction settlement of high-fill subgrade under gravity stress and vehicle loads, in situ monitoring was carried out on the Lanzhou-Yongjing highway. Single-point settlement meters were buried in variou...
This study investigates the stiffness development by bender element tests on specimens of artificially cemented clay, considering the effects of cement content, total water content and curing period. Experimental results indicate that the small-strain shear modulus of cemented clay can be well determined by cement content and total water content. A...
To investigate the strong random nature of the geometric interfaces between soil and rock, a rock-soil slope is considered as a two-phase random medium. A nonlinear translation of a Gaussian field is utilized to simulate the two-phase random media, such that the soil (or rock) volume fraction and the inclination of the soil layer can be examined. T...
This paper proposes a framework for describing the modulus degradation behavior of cement-treated soft clay. The results show that effect of the mix ratio on the modulus degradation behavior can be captured through the unconfined compressive strength only, rather than through two parameters (e.g., void ratio and cement content) as used in existing...
The impact of deep excavation to the stability of adjacent slope is evaluated based on the slip line theory. Stress field of slope under various excavation conditions is simulated by finite element method, while slip line field is determined by non-associated flow rule. Factor of safety is obtained by integrating the skid-resistance and the shear s...
Understanding mechanical behaviors of a methane hydrate–coal mixture are important for its associated application in coal and gas outburst prevention. A triaxial compression apparatus for a specimen of the methane hydrate–coal mixture was developed to measure its strength and deformation properties. Triaxial compression tests were performed on coal...
The polyethylene terephthalate/carbon black (PET/CB) composite was fabricated by twin-screw extrusion and injection molding method. The morphology, electrical conductive percolation threshold, tensile piezoresistivity, and stress-strain behavior of the composite were investigated. A scanning electron microscope showed that the carbon black was disp...
In order to analyze the displacement and stress of thin plate for cement concrete pavement with rectangle shape and resting on Winkler soil foundation, an analysis model was set up based on the theory of elastic thin plate on Winkler foundation. According to elasticity Kirchhoff theory of thin plates and Winkler soil foundation model, the expressio...
Miniature submersible linear variable differential transformer (LVDT) is commonly used for small strain stiffness measurement. However, it has not been widely used on cement-treated clays. This paper proposes a method of installing and setting up submersible LVDT to minimize testing problems and errors for cement-treated clays. In soft clay testing...
This paper examines the effect of experimental methodology on the measurement of small strain shear modulus of cement-treated marine clay using bender element. The specimens tested have cement content ranging from 20% to 50%, this being the typical range of cement content used for ground improvement in relation to underground construction. The expe...
In this paper, the construction of a section of Nanjing Metro Line 2, a shallow underground tunnel constructed with an underground mining method, was analysed. Due to the existence of two aquifer soil layers near the tunnel, water and sand inrush occurred during the tunnelling process. This disrupted tunnelling project was covered until the artific...
To investigate the stress-dependent behavior of fly-ash blended cement (FAC)-admixed marine clay, isotropic consolidated drained (CID) triaxial tests were performed in the confining pressure range of 50–350 kPa. Stress dilatancy was observed when the confining pressure was in the lowest range of 50–100 kPa. The peak strength increased linearly with...
Spatial variability in the radius of a jet-grout column is commonly encountered in practice. Although various prediction models for the column radius are available, they have been generally used to predict a nominal radius. The radius variation within a column has been seldom considered. In this study, the intracolumn radius variation was simulated...