Special Issue of Professor WANG Jianhua JIANG Xia，HUANG Wei, SUN Qiyan
In this paper, based on Biot's theory, a numerical model for wave-seabed-pipeline dynamic response was established to investigate seabed instability failure. The seabed was treated as porous medium. The model simulated the distribution of pore pressure and effective stress, and the process of liquefaction around buried pipeline under various wave loads were investigated. Partly dynamic (u-p) formulations for the wave-induced response of the seabed with pipeline were adopted. In partly dynamic analysis, the u-p formulation in which both displacement and pore pressure were field variables was adopted considering the acceleration of soil skeleton while neglecting the inertial terms associated with pore water. Using COMSOL Multiphysics, a parametric study, including the permeability, degree of saturation, buried depth and wave height was conducted to investigate the seabed response. Then, a criterion for liquefied state was used and the possibility of wave-induced liquefaction occurring in porous seabed was studied.
With the fast increasing of urban underground space developments in China, a new kind of underground construction, deep excavation group, has been developed, which means a group of adjacent / related excavations constructed at the same time or the super-large excavation divided into small pits. The excavation groups are divided into three kinds according to the special relation of different parts, including the divided, jointed, and adjacent ones. Based on the project of Shanghai International Aviation Centre excavation group, the deformation characteristics of divided excavation groups which is one of the typical types, was studied by statistical analysis method of field measured data in the research. The deformation of partition walls, lateral displacement of underground walls and ground settlement during construction were studied in detail and their differences in different location were analyzed. The differences between traditional excavation and the excavation group were also compared in the research. Research shows that the deformation of partition walls increases first and then decreases, and it is affected by the nearby excavating. In the partition zone, the average maximum lateral displacement of the undergroud wall is 0.16%H, which is smaller than the average of 0.60%H in Shanghai and the average maximum ground settlement is 0.14% H, which is also smaller than the average of 0.40% H in Shanghai. The study provides a very strong reference value for other excavation group construction and protection of sensitive buildings.
A numerical analysis method was presented to study the behavior of the laterally loaded pile considering the characteristic of the contact interface. The test data of piles under lateral loaded piles were used to analyze the effect of contact interface on laterally loaded piles. FEM was used to compare the results of the horizontal loaded single pile using different interfaces. The displacement curves of the pile computed show that as to horizontal loaded piles, there is a critical value of the depth of pile in soil, and the excess depth is useless.
Based on the shallow and deep soil deformation data, the deformation data of the aquifer and the water level, the deformation data of the infrastructure (mainly the subway tunnel, the elevated and the ground roads), we studied the deformation characteristics of the deep soil layer and shallow soil layer in Shanghai, and discussed the deformation characteristics of subway tunnels, elevated and ground roads under the combined deformation of shallow and deep soil layers, and reached the following conclusions. First, the shallow soil layers are in continuous compression, and the total amount of compression is small. The deep soil greatly compressed before 2009, and has gradually expanded since then. Second, the deformation of the confined aquifer in Shanghai is closely related to the water level of the soil layer. When the water levels of the first, second, third and fifth aquifer rise, the soil layer rapidly expands. The expansion of the fourth confined aquifer is lagging behind the rise of the soil water level. Last, deep soil layers have similar deformation trend with the infrastructure, and shallow soil layers with different thickness affect the deformation of the infrastructure. The infrastructure near the deep soil layer has obvious uplift deformation, accompanied by the expansion of deep soil layer. Under the same conditions, the infrastructure with thick shallow soil layer shows greater settlement than that with thin shallow soil.
A practical numerical example is used to simulate the excavation process of a deep foundation pit in Shanghai, and the rationality of the model is verified by comparing with the measured data. The cross wall between tunnel and diaphragm wall is studied and the influence of cross wall is discussed. By analyzing the vertical displacement of adjacent walls and the displacement of soil on both sides of diaphragm walls, the interaction principle between diaphragm wall and tunnel or diaphragm wall and soil is obtained. The force distribution of the wall in the excavation process is used to reveal the influence principle of adjacent deep excavation on underground structure (cut-and-cover tunnel). The results show that the uplift of the tunnel is mainly caused by the uplift of the nearby diaphragm wall. The influence of the diaphragm wall on the cut-and-cover tunnel is obviously greater than that of the surrounding soil. Under the influence of deep excavation, the reason for the diaphragm wall uplifting is that the friction force in the foundation pit is larger than that of outside the pit.
In this paper, an efficient multi-objective back-analysis method of tunnel engineering was proposed by using the AMALGAM as the genetic algorithm, and by using the Pareto optimal theory as the evaluation criterion. The proposed method was applied to a test section of the West Changjiang Road tunnel project. Taking horizontal displacement as one objective, and ground settlement as the other, the soil parameters of the key layers were estimated using this method. The optimal solution was compared with the measured results, which proved that the multi-objective back analysis was superior to the single-objective back analysis in accuracy. Meanwhile, predictive analysis was taken based on the results of back analysis, and was verified as feasible. This method can provide references for environmental impact analysis of tunnel engineering.
In a foundation pit group project, complex excavation stages and large number of monitor data can be encountered, so that the operators are hard to handle the analysis of the interactive impact of the excavation processes on the adjacent foundation pits. To resolve this problem, an analysis system was developed to monitor data and construct information in a foundation pit group synchronously and dynamically. The system used Microsoft SQL Server to facilitate the classification and management of the information of constructions and instrumentations, the time related fields were selected as the reference for the synchronous analysis. The visualized modeling for the excavation processes and the monitor data was conducted through the secondary development of Microsoft Visio and Excel, respectively. A console application was utilized to link and control these models. The system was applied in the synchronous and dynamic analysis of the construction processes and the monitor data in the project of Shanghai Expo foundation pit group, and exposed the interactive impact characteristics of the adjacent excavations in a global and local time/space domain. The system provided an efficient means for the analysis and verification of theories of the interactive impact in the excavation of foundation pit groups.
Artificial recharge in deep strata is an effective method to prevent land subsidence, and make the deep strata upheave to some extent. The pile foundations of elevated road are relatively deep so that the deformation of deep strata will greatly affect the elevated road. Using the numerical method, the elevated pile and the behavior of the surrounding soil at pumping and recharge loads were simulated and its deformation characteristics were discussed based on the coupled theory. The result shows that groundwater pumping can cause a large settlement of elevated road, while the artificial recharge can control the settlement effectively. Regional land subsidence is smaller than the elevated settlement, but the deformation tendency matches the elevated road well. Besides, based on an engineering project, the long-term deformation characteristic of elevated road at underground water recharge was simulated. The study shows that numerical results agree with the filed data, and the deformation characteristics of elevated piles are mainly influenced by deep strata. Using parameter analysis, the basic laws of elevated deformation were obtained, providing reference for the prediction of long-term settlement of elevated piles.
A series of laboratory tests were conducted of intacted samples of the 2nd to 6 th Shanghai clays to investigate fundamental physical properties of successive upper clay layers in Shanghai, and overconsolidation behaviors were studied through a series of standard oedometer tests and triaxial consolidated drained compression tests. Natural water content, initial void ratio, liquid/plastic limit and liquid/plastic index were found to have similar trends of variations with depth change. Due to gentle curvature of the compression curve over the preconsolidation pressure range, the work method proposed by Becker was cited to obtain the yield pressure in oedometer test, which showed that the overconsolidated ratio (OCR) of the 2nd and 6th layers were larger than 2, while those of the 3rd and 4th were about 1.15, and that of the 5th were closed to 1.40. Different characteristics of stress-strain curves in drained triaxial tests of the 2nd to 6th Shanghai clays reflect the distribution of OCR obtained in the oedometer test. The unite study method composed by oedometer and triaxial tests will contribute to further understanding of the overconsolidated behaviour of soft clays with weak structure.
Based on the modified cylinder test equipment, the wave pressure is controlled by the loading device to simulate the response of the soil under wave loading. The effects of different wave periods, wave pressure, and soil relative density on the pore pressure around the pile are studied. The maximum amplitude of the pore pressure and the liquefaction of the seabed are analyzed. The results show that the smaller wave period, wave pressure and permeability make the maximum amplitude of pore water pressure attenuates more quickly. The pore pressure in the seabed soil near the pile bottom suddenly increases. The effect of wave period, wave pressure and permeability on the pore pressure is great.
Circumferential and longitudinal strain of steel jacking pipe which is buried in deep soft soil and jacked with long distance was monitored on the spot to study internal force of pipe under construction and temperature load. The results show that internal force of a fixed section changes little due to jacking distance. For different sections, the one that is closer to the jacking machine head is affected less by jacking force. Compressive stress predominates in longitudinal direction, and is mainly affected by jacking force. However, circumferential stress is mainly due to buried depth, and maybe tensile with deep buried on top of pipe. Circumferential stress and longitudinal stress are coupling especially with large buried depth. Eccentricity of jacking force has a great effect on internal force of pipe. When jacking force is applied, longitudinal stress changes by a large margin, and returns to steady after jacking force removed. The stress in pipe can reach 25 MPa caused by 6 ℃ temperature difference, which hardly influences the using of the pipe. There is little distinction between longitudinal stress and circumferential stress. However, extreme range of temperature should be valued, and may cause destroying.
CEL (Coupled Eulerian-Lagrangian) method was used to model the pile penetration process in soft clay. Firstly, effective stress method was used in the Vumat subroutine to calculate excess pore pressure. Comparison of the experiment results (by odometer test and triaxial test) with the numerical tests demonstrated the reliability of the Vumat subroutine. The subroutine was implemented in the CEL method of Abaqus/Explicit. Pile jacking process in soft clay under undrained conditions was simulated. The soil movements, horizontal displacement, horizontal stress, excess pore pressure were analyzed. The analysis results show that the CEL method which considers excess pore pressures can simulate well the installation effects caused by pile jacking in soft clay.
Unloading effect of the deep excavation would decrease the pile's bearing capacity and increase the tensile in pile shaft. A novel test system which can control the soil stress state was developed to study the pile-soil interactive behavior. In this novel system, the normal stress on the pile-soil interface is applied by the air pressure in the triaxial cell. The soil stress along the pile axis and the movement of model pile are controlled by the double piston. The pore pressure and water flow in the soil sample are adjusted by the two water cannels on the test cell. With the monitoring part of the system, the total shear force on the interface, the relative movement of the pile, and the deformation of the soil layer can be measured during tests. The triaxial interface tests show that the limit friction resistance and friction coefficient increase with the increase of the confining pressure, and the displacement of soil also increases with the increase of the confininig pressure.
Based on the random field theory, a random finite element model of coupled unsaturated consolidation in spatial random soils was established using the covariance matrix decomposition method and Monte Carlo simulation method. The effects of spatial variability of Young's modulus and saturated permeability were investigated. The results show that the mean and standard deviation of the settlement are significantly affected by the coefficient of variation of Young's modulus, and COVE. When COVE increases, the mean and standard deviation of the settlement increase, which means the uncertainty of the settlement are increased due to the spatial variability of Young's modulus. When the correlation length of Young's modulus δlnE decreases, the standard deviation of excess pore water pressure and the surface settlement decrease due to the increased spatial averaging effect. The spatial averaging effect is more significant when the thickness of soil layer is smaller than δlnE. In general, the effect of spatial variability of ks is much less significant than that of elastic modulus, which mainly affects the unsaturated consolidation in process.
A coupled model was proposed to study the dynamic response of seabed and the mechanical response of pile under wave. The volume of fluid (VOF) method was used to track the free surface of water while the Navier-Stokes equations are regarded as governing equations of wave to investigate the dynamic interaction between the wave and the pile. Then, based on the CFD numerical model, a three-dimensional numerical coupled model of wave-seabed-pile was built to simulate the response of seabed and pile under wave. The seabed was treated as porous medium and characterized by Biot's consolidation theory and partly dynamic formulations. After the models were validated, parametric studies such as wave height, water depth and permeability were conducted and liquefaction potential was investigated.
A 3D FEM model of a single pile in saturated sandy seabed was proposed to study the reponse of pile. Meanwhile, the quasi-static method and fluid-soil coupling and contact behavior on interface was considered. Based on numerical results, responses of the pore water pressure and stress of seabed soil under wave was studied, and the deformation and internal force of the single pile were discussed. Besides, two different methods to model the pile-soil interface were discussed with a comparison of the free field seabed model and seabed model with a totally embeded pile. The results show that the pore water pressure increases significantly near the mudline and bottom of pile. Responses of pore pressure and bending moment are evidently larger in the coupling model, but the displacement response is smaller. Moreover, the totally embeded pile model is mainly affected by seabed, as the wave dominatedly acts on the model with a pile out of the seabed.
Large span double-row steel sheet piles were constructed in marine environments to serve as cofferdams of dry dock projects. Due to the construction of the dock excavation, considerable deformation of the cofferdam could occur. The deformation of the large span double-row steel sheet piles was measured during construction of a large scale dock project in Shanghai. Extensive field performance data were collected including lateral survey data and lateral inclinometer data. Construction procedures were summarized and correlated with monitoring data. The measured data were analyzed to investigate the deformation performance of the large span double-row steel sheet piles. A 2D finite-element method was also performed to study the effect of the soil reinforcement technology on deformation control of the double-row steel sheet piles.
Short-delay blasting was used in a pipe-jacking tunnel in order to pass through rock stratum. And three-dimensional finite element numerical analysis on the influence of the blasting to bored machine and surrounding ground was carried out. The effects of different ground conditions, different clogged lengths were carefully analyzed in the numerical analysis. The analysis results indicate that shock and vibration of blasting on the bored machine reduce with the increase of clogged length. An appropriate clogged length can evidently decrease the influence of blasting on the machine. The blasting vibration on the surrounding rock of full rock face is smaller than that of half rock face condition.The influence of central hole is smaller than that of peripheral hole.
Three-dimensional finite element method was used to analyze an unbraced dock excavation. Cellular diaphragm wall and high-piled slab & beam diaphragm wall were used as the retaining structures of the excavation. The soil was assumed as cross-isotropy elastic material. The calculated results of retaining wall deflections agree well with the field measurements. The calculated results show that the deformation behavior of the retaining wall is influenced by its structure form and construction sequence of the excavation. The piles in the excavation can control the deformation of the retaining wall effectively. The effect of the dock excavation on the adjacent excavation was also discussed.
Fast Lagrangian Analysis of Continua in 3 Dimensions (FLAC3D) was employed to investigate the deformation characteristics of a staged excavated and supported foundation pit. Modified Cam-clay model was adopted to model the soil behavior and the interaction between soils and retaining structures was also taken into account in the numerical model. The deflection of retaining walls, the settlement of ground surface, the heave of excavation bottom, and the movement of the deep strata outside the excavation were analyzed. The ground surface settlement curves of the numerical model are basically consistent with the empirical ones from the existing literatures, so its feasibility is proved. The numerical results provide a useful reference for the design and construction of similar deep excavation projects.
The earthquake induced liquefaction of dam foundation was analyzed using an effective-stress based, fully coupled dynamic analysis method, in which the behavior of the sandy soil is described by means of a cyclic mobility constitutive model. The paper is primarily concerned with different responses under design water table and dead water table in a reservoir. The results show that the cyclic mobility constitute model can reflect the dynamic response of liquefiable soils, and that the liquefaction zone under dead water table decreases compared with the case of design water table, but the liquefaction induced deformations increase obviously in the upstream.
The mechanical behavior of large diameter glass reinforced plastic mortar pipe for pipe-jacking was studied by tests. The compressive strength and elastic module of large diameter glass reinforced plastic mortar pipe material were presented from experiments. The failure mode of the glass reinforced plastic mortar pipe material was analyzed from the stress-strain wreck curves under pressure, and the difference of the failure characteristics between the two types of pipes were discussed. The test results show that the glass reinforced plastic mortar pipe is brittle material, and the failure mode of enlaced pipe and centrifugal pipe is different. The strength and uniformity of the centrifugal pipe is better than that of tbe enlaced pipe.
A three-dimensional finite element method by considering the properties of the diaphragm wall-soil interface was applied to analyze the excavation of a deep foundation pit in Shanghai soft ground. The simulation results were compared with the monitoring data as well as the simulation results without diaphragm wall-soil contact. The influence of diaphragm-soil interface on the deformation analysis of excavation was discussed. The results of simulation considering the properties of the diaphragm-soil interface show closer agreement with the measure ment data. Moreover, the model without diaphragm wall-soil contact generally gets smaller wall deformation and induced ground movement.
An analysis model of post-grouting bored pile and soil was built up by numerical method to simulate the bearing capacity of the pile. The results of numerical analysis on the pile load tests are agreement with the measured ones. The effects of post-grouting on bearing capacity were simulated by this method with considering the grouting volume, the strength of grouted soil body, the height of turn-up grout and the improvement of skin friction. The results show that the grouting volume and the strength of grouting soil body have a limited effect on the bearing capacity, and the increasing effect of the grouting volume is also influenced by the length of pile. The height of turn-up grout and the improvement of skin friction have a great effect on the bearing capacity, which is linearly increased with the increasing of the height of turn-up grout and the improvement of lateral friction.
The deformation of single piles in soft foundation was studied based on more than 300 in situ data of pile including the settlements at pile-top and pile-tip. The piles are divided into four types: precast concrete pile, hollow concrete pile, steel pipe pile, and cast-in-place pile. Analyzing the in situ data with elasticity theory, a simplified method to predict the shaft compression of pile was presented based on the pile length-diameter ratio. It is shown that the shaft compression of precast concrete pile is the largest, while the compression of cast-in-place pile is the smallest. Therefore, the deformation of single piles is influenced by the squeezing effect obviously. The settlement at pile bottom was calculated by the layer-wise summation method, and the modified method to compute the settlement of single piles was obtained. The comparison analysis for 300 individual piles shows that the modified method can be used to calculate the settlement of pile at working load very well.
Large settlement occurs in soft clay foundation due to surcharge loads, which will affect the behavior of the pile foundation in site and nearby. Negative piles were studied by FEM considering the pile-soil slippage and consolidation of soil. Then settlement, side displacement, and axial force of piles were discussed and analyzed by using different contact surface of two examples. The comparison between the numerical analysis and in-situ tests shows the efficiency of the method and demonstrates some rules of soil settlement, pile axial force and moment, which can be used in engineering design.
Based on the limit equilibrium theory for axially symmetric condition, the active earth pressure of circular pit obtained with slip-line method was extended to non-uniform surcharge loading. By analyzing the influence of the radius of pit and soil parameters to the active earth pressure distribution, it was achieved that the influence is identical to Rankine theory. The comparison of slip-line field and active earth pressure distribution under non-uniform and uniform surcharge loading was made, it is show n that the surcharge loading at some region only affects the earth pressure at some specific area. So, it is easy to estimate earth pressure distribution qualitatively according to the distribution of surcharge loading.
The crack isolating theory was proposed. On the basis of the crack isolating theory and the near crack line analysis method, the elasticplastic stress field near the crack line was analyzed, the laws that the length of the plastic zone along the crack line is varied with external loads were established by the matching condition of the elastic-plastic fields on the boundary, and the strength properties of rock masses were determined. The solution is a function of the geometry of the crack array. The results show that the strength of rock masses depends on the crack spacing, orientation of the cracks, the crack interface friction coefficient and the crack half-length. The conclusions are of important significance for rock masses engineering.
In order to make natural element method (NEM) be applied to calculate and analyse the elastoplastic material, through cosidering the essential elasto-plastic theory and the specialties of NEM, an algorithm for two dimensional elasto-plastic analysis based on the yield criteria of Von-Mises, Mohr-Coulomb and Drucker-Prager was presented. Each of them has an example to check its exactness and proves its advantage at precision. Those works enlarged the applicable range of NEM.
Natural element method (NEM) is a recently developed meshless method and is essentially the Galerkin method based on natural neighbour interpolation. The algorithm for calculating natural neighbour co-ordinates and their derivatives based on Lasserre's algorithm for the volume of a convex polyhedron was derived and the generalized flowchart for NEM in 3D case was presented. The algorithm can be applied to NEM in any dimensions case in fact. Two algorithms to solve the redundant constraint problem lying in Lasserre's algorithm were also presented. The example's numerical results are equal to the results of hexahedral finite element method.
The steady dynamic response of saturated soil was studied by means of Hankel transform. The liquid's inertia is considered, i. e. there is not any hypothesis. By using Hankel integral transform method, the solution of horizontal harmonic force applied to the interior or the surface of saturated soil is obtained. The general solutions of the Biot dynamic equations in frequency domain are established through the use of Hankel integral transforms technique. Utilizing the above-mentioned general solution, the boundary conditions of the surface of half-space and the continuous conditions at the plane of horizontal force, the solutions of the boundary value problem can be determined. By the numerical inverse Hankel transforms method, the stress and the displacement of harmonic horizontal force are obtainable. In the end, the numerical method of inversion of Hankel transform was given.
Based on the disturbed state concept (DSC) theory, a new constitutive model of saturated soft cohesive soil was presented through defining relative intact state, fully adjusted state and disturbed function for the saturated cohesive soil. Analyzing the mechanical characteristics of the typical saturated cohesive soil of Shanghai by consolidated-undrained triaxial shear tests, the relationship among axial stress, axial train and pore water pressure of the soil was obtained under different confining pressure. The constitutive model of cohesive soil based on the DSC theory was verified by the test results. The research shows that the theoretical analysis is in good agreement with the results of tests.
A statically admissible stress field was constructed by using nonlinear optimization sequential quadratic programming (SQP) algorithm and FEM. Based on the rigid plastic assumption for soil materials, adopting lower bound theorem, the bearing capacity of rectangular surface footing was calculated. The example indicates that the application of SQP algorithm is successful.
Based on the results of pull-out test on geotextiles, this paper presented a three-staged model for total shear stress-displacement to consider the strain softening and plastic flow. According to the mechanical characteristics of geotextiles, the non-linear differential equations are expressed in non-dimensional form and solved numerically using a finite difference method. The variation of the displacement, strain, tension and shear stress in pull-out test can be obtained. The relation between pull-out force and deformation was discussed based on the example analysis, and compared with the experimental pull-out test results. Comparison with the results of linear elastic model and hyperbolic model shows that three-staged elastic-plastic model is in good accord with practical situation.
An extremly accurate and efficient numerical method for solving the problem was presented, which is mainly by means of the crack isolating analysis technique, stress superposition principle, the Legendre polynomial expansion of the pseudo-traction as well as the segmental average collocation technique. The singular equations of the Cauchy type and Fredholm integral equations of the first type were deduced. In the process of dealing with the superposition of infinite number of kinked cracks, the crack boundary conditions are satisfied. Many complex computing examples were given, and for some typical examples, numerical results were compared with the analytic solutions and the numerical solutions obtained by a boundary element method. The numerical results show that the stress intensity factors depend on the crack configuration, and on the geometrical and physical parameters.
The paper presented a new method to implement the elastoplastic FEM analysis of softening materials by combining the algorithm of adaptive mesh generation with the algorithm of arc-length control procedures. The integration of elastoplasticity, arc-length control procedures and the algorithm of adaptive mesh generation were focused on. The flow chart of combining the algorithm of adaptive mesh generation with the algorithm of arc-length control procedures was offered. The numerical results confirm the efficiency of the present analysis method.
This article described a method for upper bound analysis. The whole process is based on nonlinear programming and linear finite elements. By solving a non-linear optimization problem, i. e., searching the minimum value of power dissipated by external forces, the upper bound loads can be obtained. The numerical examples suggest that this method is correct and practicable. It can obtain the upper bound limit load directly without considering the complicated stress strain relationship of c-O materials in traditional finite element method.
The ultimate bearing capacity of foundation based on Mohr-Coulomb strength criterion does not consider the influence of intermediate principal stress on yield and failure of soil. In this paper, the influence of mean principal stress on the ultimate bearing capacity of foundation was taken into account based on twin shear strength theory. Formulae were derived with the influence of soils cohesive strength, over-burden loads on both sides of foundation and the self weight of soils. Taking strip foundation as an example, the influence of intermediate principal stress on the ultimate bearing capacity of foundation was calculated. The ultimate bearing capacity of foundation will be improved, when the influence of intermediate principal stress on the bearing capacity of foundation is considered.
The double lines strengthening elastic-plastic model was developed by simplifying the concrete constitutive law according to Saenz formula. The formulae for the model parameters were given. The structural analysis procedure Algor was taken to conduct the linear elastic and elastic-plastic FEM analysis on the joints of segments. The strain distribution of segment, the displacement of joints, the rotary angle of joints and the tensile force of joint bolts were given. The comparison between FEM calculation and test results was made, which shows that the finite element analysis results correspond with the test results. The FEM analysis results can bean effective measure to observe the distribution patterns of the strain and stress.
Using C++ language with object-oriented feature, a P-version adaptive FEM program was designed, which contains the modules of shape function, high grade element, adaptive course and error estimate. In the function of solving linear equations, a data structure that can save storage space and computation resource was presented. The provided examples show the correction of the theory and program.
Special Issue of Professor WANG Jianhua
