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Calculation method for the formation time of dynamic filter cake in slurry shield tunneling

Frontiers of Structural and Civil Engineering 2024年第9期18卷 1337-1349页

作者： Yinzun YANG Dajun YUAN Changyan DU dalong jin Jun HAO Key Laboratory of the Ministry of Education for Urban Underground Engineering Beijing Jiaotong UniversityBeijing 100044China School of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China China Railway 14th Bureau Group Mega Shield Engineering Co. Ltd.Nanjing 211800China

In slurry shield tunneling,the stability of tunnel face is closely related to the filter *** cutting of the cutterhead has negative impact on the formation of filter *** study focuses on the formation time of dynamic filter cake considering the filtration effect and rotation of *** effect is the key factor for slurry infiltration.A multilayer slurry infiltration experiment system is designed to investigate the variation of filtrate rheological property in infiltration *** mass concentration C_(L),soil permeability coefficient k,the particle diameter ratio between soil equivalent grain size and representative diameter of slurry particles d_(10)/D_(85) are selected as independent design variables to fit the computational formula of filtration *** on the relative relation between the mass of deposited particles in soil pores and infiltration time,a mathematical model for calculating the formation time of dynamic filter cake is proposed by combining the formation criteria and formation rate of external filter *** accuracy of the proposed model is verified through existing experiment *** results show that filtration coefficient is positively correlated with slurry mass concentration,while negatively correlated with the soil permeability coefficient and the particle diameter ratio between soil and *** infiltration distance increases,the adsorption capacity of soil skeleton to slurry particles gradually *** formation time of external filter cake is significantly lower than internal filter cake and the ratio is approximately *** the dynamic cutting of the cutterhead,the formation time is positively associated with the rotation speed of cutter head,while negatively with the phase angle difference between adjacent cutter *** formation rate of external filter cake is greater than 98%when d_(10)/D_(85)≤*** increasing the content or decreasing the diameter size of solid-phase

关键词： slurry infiltration filtration coefficient dynamic filter cake formation time rotation speed phase angle

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Prediction of fracture initiation in cohesive soils based on data mining modelling and large-scale laboratory verification

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Underground Space 2024年第6期19卷 279-300页

作者： Weiping Luo Dajun Yuan Yannick Choy Hing Ng dalong jin Ping Lu Teng Wang Department of Geotechnical Engineering College of Civil EngineeringTongji UniversityShanghai 200092China Key Laboratory of the Ministry of Education for Urban Underground Engineering Beijing Jiaotong UniversityBeijing 100044China Department of Civil and Environmental Engineering National University of SingaporeSingapore 119077Singapore

Many empirical and analytical methods have been proposed to predict fracturing pressure in cohesive *** of them take into account three to four specific influencing factors and rely on the assumption of a failure *** this study,a novel data-mining approach based on the XGBoost algorithm is investigated for predicting fracture initiation in cohesive *** has the advantage of handling multiple influencing factors simultaneously,without pre-determining a failure mode.A dataset of 416 samples consisting of 14 distinct features was herein collected from past studies,and used for developing a regressor and a classifier model for fracturing pressure prediction and failure mode classification *** results show that the intrinsic characteristics of the soil govern the failure mode while the fracturing pressure is more sensitive to the stress *** XGBoost-based model was also tested against conventional approaches,as well as a similar machine learning algorithm namely random forest ***,several large-scale triaxial fracturing tests and an in-situ case study were carried out to further verify the generalization ability and applicability of the proposed data mining approach,and the results indicate a superior performance of the XGBoost model.

关键词： Fracturing pressure Failure mode Cohesive soil Data-mining Large-scale tests

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Effect of cutterhead configuration on tunnel face stability during shield machine maintenance outages

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Frontiers of Structural and Civil Engineering 2023年第4期17卷 522-532页

作者： Yinzun YANG Dajun YUAN dalong jin Key Laboratory of the Ministry of Education for Urban Underground Engineering Beijing Jiaotong UniversityBeijing 100044China School of Civil Engineering Beijing Jiaotong UniversityBeijing 100044China

Owing to long-distance advancement or obstacles,shield tunneling machines are typically shut down for *** safety during maintenance outages is determined by the stability of the tunnel *** maintenance openings are typically used under complicated hydrogeological *** tunnel face is supported by a medium at the bottom of the excavation chamber and compressed air at the *** to the high risk of face failure,the necessity of support pressure when cutterhead support is implemented and a method for determining the value of compressed air pressure using different support ratios must to be *** this study,a non-fully chamber supported rotational failure model considering cutterhead support is developed based on the upper-bound theorem of limit *** simulation is conducted to verify the accuracy of the proposed *** results indicate that appropriately increasing the specific gravity of the supporting medium can reduce the risk of *** required compressed air pressure increases significantly as the support ratio *** the supporting effect of the cutterhead will result in a tunnel face with underestimated *** satisfy the requirement of chamber openings at atmospheric pressure,the stratum reinforcement strength and range at the shield end are provided based on different cutterhead aperture ratios.

关键词： tunnel face stability cutterhead configuration aperture ratio pressure gradient support ratio

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Experimental study on slurry-induced fracturing during shield tunneling

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Frontiers of Structural and Civil Engineering 2021年第2期15卷 333-345页

作者： Teng WANG Dajun YUAN dalong jin Xinggao LI Key Laboratory of Urban Underground Engineering of the Education Ministry Beijing Jiaotong UniversityBeijing100044China

Facial support in slurry shield tunneling is provided by slurry pressure to balance the external earth and water *** fracturing may occur and cause a significant decrease in the support pressure if the slurry pressure exceeds the threshold of the soil or rock material,resulting in a serious face collapse *** the occurrence of hydraulic fracturing in a slurry shield requires investigating the effects of related influencing factors on the hydraulic fracturing pressure and fracture *** this study,a hydraulic fracturing apparatus was developed to test the slurry-induced fracturing of cohesive *** effects of different sample parameters and loading conditions,including types of holes,unconfined compressive strength,slurry viscosity,and axial and circumferential loads,on the fracturing pressure and fracture dip were *** results indicate that the fracture dip is mainly affected by the deviator *** fracturing pressure increases linearly with the increase in the circumferential pressure,but it is almost independent of the axial *** unconfined compressive strength of soil can reflect its ability to resist fracturing *** fracturing pressure increases with an increase in the unconfined compressive strength as well as the slurry *** on the test results,an empirical approach was proposed to estimate the fracturing pressure of the soil.

关键词： slurry shield tunneling hydraulic fracturing test fracturing pressure fracture dip unconfined compressive strength slurry viscosity

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Hydraulic fracturing pressure of concentric double-layered cylinder in cohesive soil

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Frontiers of Structural and Civil Engineering 2021年第4期15卷 937-947页

作者： Dajun YUAN Weiping LUO dalong jin Ping LU Key Laboratory of Urban Underground Engineering of the Education Ministry Beijing Jiaotong UniversityBeijing100044China School of Civil Engineering Beijing Jiaotong UniversityBeijing100044China

This study aims to investigate hydrofracturing in double-layered soil through theoretical and experimental analysis,as multilayered soils where the difference in mechanical properties exists are generally encountered in practical ***,an analytical solution for fracturing pressure in two different concentric regions of soil was presented based on the cavity expansion ***,several triaxial hydraulic fracturing tests were carried out to validate the analytical *** comparison between the experimental and analytical results indicates the remarkable accuracy of the derived formula,and the following conclusions were also ***,there is a linear relationship between the fracturing pressure and confining pressure in concentric double-layered cohesive ***,when the internal-layer soil is softer than the external-layer soil,the presence of internal soil on the fracturing pressure approximately brings the weakening effect,and the greater strength distinction between the two layers,the greater the weakening ***,when the internal-layer soil is harder than the external-layer soil,the existence of the internal-layer soil has a strengthening effect on the fracturing pressure regardless of the proportion of internal-layer ***,the influence of strength distinction between the two layers on the fracturing pressure is significant when the proportion of internal-layer soil is less than half,while it’s limited when the proportion is more than *** proposed solution is potentially useful for geotechnical problems involving aspects of cohesive soil layering in a composite formation.

关键词： hydraulic fracturing pressure layered cavity expansion theory triaxial fracturing test cohesive soil

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Probabilistic analysis of secant piles with random geometric imperfections

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Frontiers of Structural and Civil Engineering 2021年第3期15卷 682-695页

作者： Yi YANG dalong jin Xinggao LI Weilin SU Xuyang WANG Key Laboratory of Urban Underground Engineering of the Education Ministry School of Civil EngineeringBeijing Jiaotong UniversityBeijing100044China

The failure to achieve minimum design overlap between secant piles compromises the ability of a structure to perform as designed,resulting in water leakage or even ground *** establish a more realistic simulation and provide guidelines for designing a safe and cost-effective secant-pile wall,a three-dimensional model of a secant pile,considering the geometric imperfections of the diameter and direction of the borehole,is *** ultrasonic cross-hole test was performed during the construction of secant piles in a launching shaft in Beijing,*** on the test results,the statistical characteristics of the pile diameters and orientation parameters were *** taking the pile diameter D,inclination angleβ,and azimuth angleαas random variables,Monte Carlo simulations were performed to discuss the influence of different design parameters on the probability density functions of the overlap of secant *** obtained results show that the randomness of the inclination angle and pile diameter can be well described by a normal distribution,whereas the azimuth angle is more consistent with a uniform *** integrity of the secant-pile wall can be overestimated without considering the uncertainty of geometric *** failure of the secant-pile wall increases substantially with increasing spatial variability in drilling inclination and diameter.A design flowchart for pile spacing under the target safety level is proposed to help engineers design a safe and economical pile wall.

关键词： secant piles ultrasonic cross-hole testing probabilistic analysis reliability-based design random imperfections

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Optimal Control of Slurry Pressure during Shield Tunnelling Based on Random Forest and Particle Swarm Optimization

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Computer Modeling in Engineering & Sciences 2021年第7期128卷 109-127页

作者： Weiping Luo Dajun Yuan dalong jin Ping Lu Jian Chen Key Laboratory of Urban Underground Engineering of the Education Ministry Beijing Jiaotong UniversityBeijing100044China School of Civil Engineering Beijing Jiaotong UniversityBeijing100044China China Railway 14 Bureau Group Co. Ltd.Jinan250101China

The control of slurry pressure aiming to be consistent with the external water and earth pressure during shield tunnelling has great significance for face stability,especially in urban areas or underwater where the surrounding environment is very sensitive to the fluctuation of slurry *** this study,an optimal control method for slurry pressure during shield tunnelling is developed,which is composed of an identifier and a *** established identifier based on the random forest(RF)can describe the complex non-linear relationship between slurry pressure and its influencing *** proposed controller based on particle swarm optimization(PSO)can optimize the key factor to precisely control the slurry pressure at the normal state of advancement.A data set from Tsinghua Yuan Tunnel in China was used to train the RF model and several performance measures like R2,RMSE,etc.,were employed to ***,the hybrid RF-PSO control method is adopted to optimize the control of slurry *** good agreement between optimized slurry pressure and expected values demonstrates a high identifying and control precision.

关键词： Shield tunnelling slurry pressure optimal control random forest particle swarm optimization

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European Integration:Reality and Ideal

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国际交流：英文版 2010年第1期 14-18页

作者： jin dalong Shi Dongmei

In the present world, the European Union is the largest union of states with the highest level of integration. From the creation of the

关键词：欧洲联盟一体化理想意大利比利时卢森堡

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考虑土体流变特性的盾构机-土体相互作用研究

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土木工程学报 2020年第S1期53卷 57-62页

作者：金慧袁大军金大龙北京交通大学城市地下工程教育部重点实验室北京100044 北京交通大学隧道及地下工程教育部工程研究中心北京100044 北京交通大学土木建筑工程学院北京100044

针对掘进状态下盾构机-土体相互作用问题,考虑土体流变特性,基于黏弹性理论和叠加原理,建立了盾构机-土体相互作用模型,提出了考虑盾构机结构特点,掘进速度和土体流变时效性的盾构机和周围土体间接触应力的计算方法,得到盾构机-土体接... 详细信息

针对掘进状态下盾构机-土体相互作用问题,考虑土体流变特性,基于黏弹性理论和叠加原理,建立了盾构机-土体相互作用模型,提出了考虑盾构机结构特点,掘进速度和土体流变时效性的盾构机和周围土体间接触应力的计算方法,得到盾构机-土体接触应力与地层初始应力,开挖半径和时间成正比,与土体位移成反比。将黏弹性解与弹性解进行了对比,结果显示考虑流变作用推导的黏弹性解大于弹性解。对土体黏性系数、盾构机掘进速度和停机时间对盾构机-土体接触应力的影响规律进行了分析,结果显示盾构机-土体接触应力随着黏性系数的增大逐渐减小并趋于稳定,随掘进速度的增大逐渐减小并逼近于弹性接触应力分布曲线,随着停机时间的增加逐渐增大并逐渐达到稳定。

关键词：盾构土体流变特性盾构机-土体相互作用黏弹性解

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Identification,characterization,and verification of miR399 target gene in grape

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Horticultural Plant Journal 2024年第1期10卷 91-102页

作者： Maosong Pei Hainan Liu Tonglu Wei Huiying jin Yihe Yu Mengting Ma Xiaomeng Song Rundong Dai dalong Guo Henan Engineering Technology Research Center of Quality Regulation and Controlling of Horticultural Plants College of Horticulture and Plant ProtectionHenan University of Science and TechnologyLuoyangHenan 471023China

The microRNA miR399 plays an important role in phosphorus signal transduction pathways in ***,miR399 was shown to be closely associated with berry ripening in grape(Vitis vinifera).The objective of the present study was to elucidate the evolutionary characteristics of the miR399 gene family in grape and to verify the cleavage effect on the target *** miR399s were identified by miRNA sequencing and retrieval from the miRBase *** mature sequences and precursor sequences were subjected to phylogenetic analysis to reconstruct evolutionary trees,as well as secondary structure analysis of the precursor sequence,and prediction of target *** cisacting elements in the miR399 promoter were predicted and the cleavage effect of grape miR399b on its target genes was *** grape miR399 family comprised nine precursor sequences and nine mature *** precursor sequences formed a typical and stable stem—loop *** minimum folding free energy ranged from-55.70 kcal·mol^(-1)to-37.40 kcal·mol^(-1).Multiple sequence alignment revealed that the miR399 family was highly *** grape miR399 family was phylogenetically closely related to peach,apple,and citrus *** miR399s were predicted to target inorganic phosphate transporter 1—3,phospholipase D delta-like,and *** cleavage effect of grape miR399b on the target genes was verified by means of a dual-luciferase assay and 5’*** GUS staining showed that the promoter activity of miR399b was promoted by GA3treatment.

关键词： Grape miR399 Phosphorus metabolism Early ripening

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