Experimental Investigation on the Effect of Volume Loss on Ground Movements Induced by Tunnelling in Sand

Tianzuo Wang,Ruipeng Wang,Fei Xue,Ningbo Tang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.1

Complex ground conditions or support failures during tunnel construction can lead to high ground loss, which may cause damage to surrounding structures. In this paper, a series model tests are carried out in order to clarify tunnelling-induced ground deformation at high ground loss conditions. The model tunnel in this test is shallowly buried in loose sand and the tunnel volume loss (Vl,t) is set from 4% to 10%. The Vl,t is controlled by a water-filling-drainage system and the ground deformation is monitored by digital image correlation (DIC) system. The results show that the Peck-Gaussian function can be used to fit the settlement data well, and the increase of Vl,t has no significant effect on the width of the settlement trough, while the horizontal displacement can be described by modified empirical method. The width of influence aera caused by tunnelling decreases linearly with depth, and the width near the tunnel crown is about 78% of that on the surface. For loose sand ground, it is the shear band rather than the soil arch that dominates the ground deformation. Furthermore, excavation leads to a volume contraction of the ground, which suggests predictions based on tunnel over-excavation trend to underestimate the ground deformation, and that should be taken seriously in consideration of the safety of the engineering project. This study can provide a better understanding of ground deformation induced by tunnelling.

A Rock Mass Strength Prediction Method Integrating Wave Velocity and Operational Parameters based on the Bayesian Optimization Catboost Algorithm

Yaxu Wang,Ruirui Wang,Jiwen Wang,Ningbo Li,Hongyi Cao 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.7

Tunnel Boring Machines (TBMs) have been the main equipment for tunneling and underground construction due to their high safety performance and tunneling efficiency. However, the unknown and changing geological conditions during construction pose a challenge to TBM construction. As one of the essential parameters of rock properties, accurate acquisition of uniaxial compressive strength (UCS) is crucial for TBMs to adapt to changing ground conditionsin a timely manner. Therefore, this study proposes a Catboost intelligent model based on Bayesian Optimization to predict UCS. Rock mass are velocity information and key TBM operational parameters are used as model input variables. The Gaussian data augmentation method is used to compensate for the difficulty of obtaining field data in large quantities. The Zhujiang Delta Water Resources Allocation Engineering field data are used in the model, and the obtained evaluation indicators MAPE, RMSE, VAF and a20-index are obtained as 9.91%, 499.38 MPa, 90.7% and 0.95, respectively. In addition, another project is selected to verify the applicability of the model. The validation results also confirm that the model is valid and reliable when applied to practical engineering.

Depoling of porous Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 ferroelectric ceramics under shock wave load

Ningbo Feng,Hengchang Nie,Xuefeng Chen,Genshui Wang,Xianlin Dong,Hongliang He 한국물리학회 2010 Current Applied Physics Vol.10 No.6

Poled Pb0.99(Zr0.95Ti0.05)0.98Nb0.02O3 ferroelectric ceramics in different porosity depoled under shock wave load. Porosity and material dielectric characteristic effects on the depoling current evolution were discussed. The results showed that under open circuit condition, the dielectric constant of all samples exhibited obvious increase, but as the porosity increased, the dielectric constant decreased. As a result of lower dielectric constant of porous samples during depoling process, the charge-releasing rate is faster than that of dense sample.

Multi-energy coordinated regulation strategy based on the decomposition of large-scale new energy fluctuations

BAO Guangqing,ZHOU Jiawu,MA Ming,WANG Ningbo 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

The high volatility and weak support of wind, photovoltaic power generation and other new energy sources have a negative impact on the stability of the power system. Therefore, the power spectrum density of the power curve compensating the combined output of wind power and photovoltaic power was analyzed by discrete Fourier transform (DFT)based on the study of the random fluctuation characteristics of wind power and photovoltaic output, and the multi-energy frequency division compensation control mode of thermal power, hydropower and energy storage was proposed to deal with the fluctuation of high proportion of new energy grid-connection.Firstly, the wave compensation is decomposed into low frequency, medium frequency and high frequency components by two wavelet packet decomposition.Then the annual operating cost is minimized to optimize the capacity of different compensation units according to the output characteristics of differ-ent energy units on the basis of introducing the penalty coefficient of fluctuation. By analyzing the data of wind farm group and photovoltaic power station in a western region, the correctness and feasibility of the proposed scheduling optimization method are verified.

Study on Multi-scale Unit Commitment Optimization in the Wind-Coal Intensive Power System

Xi YE,Ying QIAO,Zongxiang LU,Yong MIN,Ningbo Wang 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.6

Coordinating operation between large-scale wind power and thermal units in multiple time scale is an important problem to keep power balance, especially for the power grids mainly made up of large coal-fired units. The paper proposes a novel operation mode of multi-scale unit commitment (abbr. UC) that includes mid-term UC and day-ahead UC, which can take full advantage of insufficient flexibility and improve wind power accommodation. First, we introduce the concepts of multi-scale UC and then illustrate the benefits of introducing mid-term UC to the wind-coal intensive grid. The paper then formulates the mid-term UC model, proposes operation performance indices and validates the optimal operation mode by simulation cases. Compared with day-ahead UC only, the multi-scale UC mode could reduce the total generation cost and improve the wind power net benefit by decreasing the coal-fired units’ on/off operation. The simulation results also show that the maximum total generation benefit should be pursued rather than the wind power utilization rate in wind-coal intensive system.

Optimizing bioconversion of ferulic acid to vanillin by Bacillus subtilis in the stirred packed reactor using Box-Behnken design and desirability function

Peng Chen,Lei Yan,Shuang Zhang,Zhengrong Wu,Suyue Li,Xiaojuan Yan,Ningbo Wang,Ning Liang,Hong Yu Li 한국식품과학회 2017 Food Science and Biotechnology Vol.26 No.1

A stirring bioreactor packed with a carbon fiber textiles (FT) biofilm formed by Bacillus subtilis was used to produce vanillin from ferulic acid. Biofilm formation was characterized by scanning electron microscopy. The interactive effects of three variables on vanillin molar yield (M) and conversion efficiency of ferulic acid (E) were evaluated by response surface methodology (RSM) with a Box-Behnken design (BBD). The optimal conversion conditions with a maximum overall desirability D of 0.983 were obtained by a desirability function. Considering the actual operation, the confirmation tests were performed using the slightly modified optimal conditions (initial ferulic acid concentration 1.55 g/ L, temperature 35oC, stirring speed 220 rpm). The results showed that M and E were 57.42 and 93.53%, respectively. This was only 1.03% and 1.87%, respectively, different from the predicted values, confirming the validity of the predicted models. These revealed that the stirred packed reactor could be successfully used in vanillin bioconversion from ferulic acid.

Effects of Supplementing Different Levels of a Commercial Enzyme Complex on Performance, Nutrient Availability, Enzyme Activity and Gut Morphology of Broilers

Yuan, Jiu,Yao, Junhu,Yang, Fengxia,Yang, Xiaodan,Wan, Xinjie,Han, Jincheng,Wang, Yaojie,Chen, Xinke,Liu, Yurui,Zhou, Zhenfeng,Zhou, Ningbo,Feng, Xinyu Asian Australasian Association of Animal Productio 2008 Animal Bioscience Vol.21 No.5

A trial was conducted to study the influence of different levels of a commercial enzyme complex on performance, nutrient availability, blood parameters, digestive tract measurements, amylase and trypsin activity of the digestive tract and gut morphology in broilers fed the typical diets in north China. There were four treatments: the control diet and the other three enzyme complex supplemented diets which were 180 mg/kg, 360 mg/kg and 720 mg/kg enzyme complex supplemented to the control diet, respectively. The birds fed the diets supplemented with 180 mg/kg and 360 mg/kg enzyme complex had better performance and nutrient availability, the activities of amylase and trypsin in the digestive tract in the two treatments were improved, the villus height and surface area of villus in the small intestine increased and the crypt depth and epithelial thickness of small intestine decreased. Relative weights of pancreas and relative weights and lengths of small intestine decreased. However, the addition of 720 mg/kg enzyme complex had no effects on these parameters and increased crypt depth and epithelial thickness of the small intestine. The data suggested that suitable supplementation of enzyme complex was beneficial for the birds, while excess enzyme complex inhibited secretion of endogenous enzyme and destroyed the structure of the small intestine.

Study on Multi-scale Unit Commitment Optimization in the Wind-Coal Intensive Power System

Ye, Xi,Qiao, Ying,Lu, Zongxiang,Min, Yong,Wang, Ningbo The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.6

Coordinating operation between large-scale wind power and thermal units in multiple time scale is an important problem to keep power balance, especially for the power grids mainly made up of large coal-fired units. The paper proposes a novel operation mode of multi-scale unit commitment (abbr. UC) that includes mid-term UC and day-ahead UC, which can take full advantage of insufficient flexibility and improve wind power accommodation. First, we introduce the concepts of multi-scale UC and then illustrate the benefits of introducing mid-term UC to the wind-coal intensive grid. The paper then formulates the mid-term UC model, proposes operation performance indices and validates the optimal operation mode by simulation cases. Compared with day-ahead UC only, the multi-scale UC mode could reduce the total generation cost and improve the wind power net benefit by decreasing the coal-fired units' on/off operation. The simulation results also show that the maximum total generation benefit should be pursued rather than the wind power utilization rate in wind-coal intensive system.