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Revisiting the theoretical prediction of the explosive performance found by the Trauzl test

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Defence Technology（防务技术） 2024年第6期36卷 163-174页

作者： Ivana Dobrilovic Mario Dobrilovic Muhamed Suceska Faculty of Mining Geology and Petroleum EngineeringDepartment of Mining Engineering and GeotechnicsUniversity of ZagrebPierottijeva 6Zagreb10000Croatia

The Trauzl lead block test allows the determination of the approximate performance of explosives in blasting applications by measuring the volume increase(expansion)that is produced by the detonation of an explosive charge in the cavity of a lead *** this paper,we reconsider the possibility of interpreting the Trauzl test results in terms of detonation parameters or *** detonation parameters used in the analysis are calculated using the thermochemical code EXPLO5,while the hydrocode AUTODYN is used to simulate the effect of explosive charge density and reaction rate on the results of the Trauzl *** increase in the volume of the lead block cavity was found to correlate best with the product of the detonation heat and the root of the volume of detonation *** simulation showed that the density of explosive charge and the rate of explosive decomposition affect the dynamics of the interaction of the detonation product and the lead block,and consequently the lead block cavity volume increase.

关键词： Trauzl lead block test Performance of explosives EXPLO5 AUTODYN Detonation heat

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Deformation-based longitudinal equivalent stiffness beam model for shield tunnel and its application in seismic deformation method

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Underground Space 2024年第4期17卷 280-299页

作者： Pingliang Chen Ping Geng Junbo Chen Qi Yang Key Laboratory of transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China State Key Laboratory of Intelligent geotechnics and Tunnelling Chengdu 610031China Technology Center of Sichuan Road&Bridge Group Co. LtdChengdu 610041China

In the longitudinal seismic deformation method for shield tunnels,one of the most commonly used is the longitudinal equivalent stiffness beam model(LES)for simulating the mechanical behavior of the *** this model,axial deformation and bending deformation are independent,so the equivalent stiffness is a constant ***,the actual situation is that axial deformation and bending deformation occur simultaneously,which is not considered in *** present,we are not clear about the effect on the calculation results when axial deformation and bending deformation occur ***,in this paper,we improve the traditional LES by taking the relative deformation as a load and considering the coordinated deformation of axial and bending degrees of *** improved model is called DNLES,and its neutral axis equations are an explicit ***,we propose an iterative algorithm to solve the calculation model of the DNLES-based longitudinal seismic deformation *** a calculation example,we find that the internal forces based on LES are notably underestimated than those of DNLES in the compression bending zone,while are overestimated in the tension bending *** considering the combined effect,the maximum bending moment reached 13.7 times that of the LES model,and the axial pressure and tension were about 1.14 and 0.96 times,*** analysis reveals the coordinated deformation process in the axial and bending directions of the shield tunnel,which leads to a consequent change in equivalent *** explains why,in the longitudinal seismic deformation method,the traditional LES may result in unreasonable calculation results.

关键词： Shield tunnel Longitudinal seismic deformation method Longitudinal equivalent stiffness beam Combined axial and bending deformation

Deformation and stability of the seawall,considering the strength uncertainty of cement mixing piles

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第6期25卷 483-501页

作者： Yuansheng YU Lingling LI Xiangmiao KONG Chengyuan LI Zhen GUO Key Laboratory of Offshore geotechnics and Material of Zhejiang Province College of Civil Engineering and ArchitectureZhejiang UniversityHangzhou310058China Hainan Institute Zhejiang UniversitySanya572000China Ninghai Highway and transportation Management Center Ningbo315600China Ninghai Traffic Engineering Construction Management Institute Ningbo315600China

The cement mixing (CM) pile is a common method of improving soft offshore ground. The strength growth of CM piles under complex conditions is affected by many factors, especially the cement and moisture contents, and shows significant uncertainty. To investigate the stochasticity of the early strength of CM piles and its impact on the displacement and stability of a seawall, a series of laboratory tests and numerical analyses were carried out in this study. Vane shear tests were conducted on the cement-solidified soil to determine the relationships between the undrained shear strength s_(u) of the cement soil curing in the seawater and the cement content a_(c), as well as the in situ soil moisture content w. It can be inferred that the 24 h undrained shear strength follows a normal distribution. A numerical model considering the random CM pile strength was established to investigate the deformation of the seawall. Due to the uncertainty of CM pile strength, the displacement of the seawall demonstrates a certain discreteness. The decrease of the mean undrained shear strength of CM piles causes a corresponding increase in the average displacement of the seawall. When the mean strength of CM piles is lower than a certain threshold, there is a risk of instability. Furthermore, the heterogeneity of the strength within an individual CM pile also has an impact on seawall displacement. Attention should be paid to the uncertainty of CM pile strength to control displacement and stability.

关键词： Construction uncertainty Cement mixing(CM)pile Strength of cement soil Seawall stability Random finite element method(RFEM) Monte Carlo simulation(MCS)

Enhanced air-coupled impact echo technique by phase analysis of signals from multiple sensors

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 297-310页

作者： Najjiya Almallah Nenad Gucunski New Jersey department of transportation New Jersey 08625USA department of Civil&Environmental Engineering Rutgers University-New BrunswickNJ 08854USA

This paper presents an air-coupled impact echo(IE)technique that relies on the phase spectrum of the collected data to find the frequencies corresponding to the reflections from *** proposed technique takes advantage of the fact that the IE compression wave is not a propagating wave,but it is the 1st order symmetrical(S1)mode Lamb wave at zero group velocity(S1-ZGV).Therefore,it searches the phase spectra of the data collected by multiple sensors to locate the frequency corresponding to the lowest phase *** a result,the technique reduces the effect of propagating waves,including the direct acoustic wave and ambient *** is named the Constant Phase IE(CPIE).The performance of the CPIE is experimentally compared with the regular amplitude spectrum-based IE technique and two other multisensor IE *** CPIE shows a performance advantage,especially in a noisy environment.

关键词： nondestructive testing(NDT) nondestructive evaluation(NDE) bridge inspection bridge evaluation impact echo bridge delamination concrete bridge deck air-coupled sensing MEMS

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Heterogeneities of grain boundary contact for simulation of laboratoryscale mechanical behavior of granitic rocks

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2629-2644页

作者： Xiongyu Hu Marte Gutierrez Zhiwei Yan Key Laboratory of transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu610031China University transportation Center for Underground transportation Infrastructure Colorado School of MinesGoldenUSA School of Civil Engineering Southwest Jiaotong UniversityChengdu610031China

From a practical point of view,grain structure heterogeneities are key parameters that control the rock response and still remains a challenge to incorporate in a quantitative *** of the less discussed topics in the context of the grain-based model(GBM)in the particle flow code(PFC)is the contact heterogeneities and the appropriate contact model to mimic the grain boundary ***,the smooth joint(SJ)model and linear parallel bond(LPB)model are used to simulate the grain boundary ***,the literature does not document the suitability of different models for specific *** challenge in implementing GBM in PFC is that only a single bonding parameter is used at the grain *** aim of this study is to investigate the responses of a laboratory-scale specimen with SJ and LPB models,considering grain boundary heterogeneous and homogeneous contact *** and biaxial compression tests are performed to calibrate the response of Creighton *** stressestrain curves,volumetric dilation,inter-crack(crack in the grain boundary),and intra-crack(crack within the grain)development,and failure patterns associated with different contact models are *** was found that both the SJ and LPB models can reproduce the pre-peak behavior observed for a granitic rock ***,the LPB model is unable to reproduce the post-peak *** to the large interlocking effect originating from the balls in contact and the ball size in the LPB model,local dilation is induced at the grain *** overestimates the volumetric dilation and residual shear *** LPB model tends to result in discontinuous inter-cracks and stress localization in the rock specimen,resulting in fine fragments at the rock surface during failure.

关键词： Grain boundary contact Smooth joint(SJ)model Linear parallel bond(LPB)model Contact heterogeneities Particle flow code(PFC) Granitic rock

Three-year field study on grass growth and soil hydrological properties in biochar-amended soil

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2764-2774页

作者： Haowen Guo Charles Wang Wai Ng Junjun Ni Qi Zhang Yuchen Wang department of Civil and Environmental Engineering The Hong Kong University of Science and TechnologyHong KongChina School of transportation Southeast UniversityNanjingChina

Field monitoring was conducted to investigate and quantify the long-term effects of peanut shell biochar on soil-grass interaction over three *** 10 m5 m grassed plots were constructed in completely decomposed granitic *** of them were amended,respectively,with 5%and 10%biochar contents(m^(3)/m^(3))for grass growth,while the third was without biochar *** the threeyear monitoring,plant characteristics,saturated water permeability(k_(s))of grassed soil and soil suction were *** monitored results show that the grass leaf area index(LAI)and root length density(RLD)with biochar amendment were improved by 38%and 200%,*** the grassed plot without biochar,a threshold RLD existed with a value of 1.7 cm/cm^(3),beyond which k_(s) raised *** threshold RLD increased by 52%when biochar content increased from 0%to 10%.This implies that biochar may restrict the increase in k_(s) of grassed soil due to the rise in the threshold *** presence of biochar and grass can retain over 100%higher suction after heavy rainfalls,while 54%lower peak suction under evapotranspiration(ET)compared with the non-amended *** can alleviate the negative effects on hydraulic properties caused by plant growth and reduce ET-induced excessive water loss.A 5%peanut shell biochar content is recommended for the long-term management of vegetated earthen infrastructures.

关键词： Soil-grass interaction Biochar Long-term Water infiltration Soil drying

Chaotic Aquila Optimization Algorithm for Solving Phase Equilibrium Problems and Parameter Estimation of Semi-empirical Models

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Journal of Bionic Engineering 2024年第1期21卷 486-526页

作者： Oguz Emrah Turgut Mert Sinan Turgut Erhan Kırtepe department of Industrial Engineering Faculty of Engineering and ArchitectureIzmir Bakircay UniversityMenemenizmirTurkey department of Mechanical Engineering Faculty of EngineeringEge UniversityBornovaizmirTurkey department of Motor Vehicles and transportation Technologies Sirnak UniversitySirnakTurkey

This research study aims to enhance the optimization performance of a newly emerged Aquila Optimization algorithm by incorporating chaotic sequences rather than using uniformly generated Gaussian random *** work employs 25 different chaotic maps under the framework of Aquila *** considers the ten best chaotic variants for performance evaluation on multidimensional test functions composed of unimodal and multimodal problems,which have yet to be studied in past literature *** was found that Ikeda chaotic map enhanced Aquila Optimization algorithm yields the best predictions and becomes the leading method in most of the *** test the effectivity of this chaotic variant on real-world optimization problems,it is employed on two constrained engineering design problems,and its effectiveness has been ***,phase equilibrium and semi-empirical parameter estimation problems have been solved by the proposed method,and respective solutions have been compared with those obtained from state-of-art *** is observed that CH01 can successfully cope with the restrictive nonlinearities and nonconvexities of parameter estimation and phase equilibrium problems,showing the capabilities of yielding minimum prediction error values of no more than 0.05 compared to the remaining algorithms utilized in the performance benchmarking process.

关键词： Aquila optimization algorithm Chaotic maps Parameter estimation Phase equilibrium Unconstrained optimization

MCS-based quantile value approach for reliability-based design of tunnel face support pressure

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Underground Space 2024年第5期18卷 187-198页

作者： Bin Li Changxing Wang Hong Li department of Road and Bridge Engineering School of Transportation and Logistics EngineeringWuhan University of TechnologyWuhan 430063China Hubei Highway Engineering Research Center Wuhan 430063China

This paper develops a new approach for reliability-based design(RBD)of tunnel face support pressure from a quantile value perspective.A surrogate model is constructed to calculate the collapse pressures of the random samples generated by a single run of Monte Carlo simulation(MCS).The cumulative distribution function(CDF)of the collapse pressure is then obtained and the support pressure aiming at a target failure probability is chosen as the upper quantile value of the collapse *** proposed approach does not require repetitive reliability analyses compared to the existing ***,a direct relationship between the target failure probability and the required support pressure is *** illustrative example is used to demonstrate the implementation *** accuracy of the reliability-based support pressures is verified by direct MCS incorporating with three-dimensional numerical ***,the influencing factors,including the sample size of MCS,the correlation coefficient between random variables,the choice of experimental points,and the surrogate model,are *** method can play a complementary role to available approaches due to its advantages of simplicity and efficiency.

关键词： Tunnel face stability Support pressure Reliability-based design Response surface method Monte Carlo simulation

Effect of helmet-wearing regulation on electric-bike riders:a case study of two cities in China

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transportation Safety and Environment 2024年第3期6卷 62-70页

作者： Wenxin Ma Zhiyong Liu Ruimin Li department of Civil Engineering Tsinghua UniversityBeijing 100084China School of Traffic and transportation Beijing Jiaotong UniversityBeijing 100044China

Objectives:Electric bikes(e-bikes)are widely used for commuting and delivery in *** the rapid increase in e-bikes on the road,related accidents have become crucial issues threatening the *** research aims to explore the protective effect of helmet-wearing regulation and to investigate some factors influencing head injury with reference to two case cities in China,obtaining information to protect e-bike ***:The traffic police-reported crash data cover the periods before and after the implementation of helmet-wearing regulations in Taizhou(with data from 2017 to 2019)and Nanning(with data in 2020)of *** statistical analysis,logistic regression and chi-square test with a Bonferroni correction were applied in the ***:A lack of helmets was common among victims in the context of a high helmet-wearing rate among general e-bike riders in Taizhou,indicating that fatality could be avoided to some extent by wearing ***,helmet wearing could reduce the probability of suffering fatal head injury by 6.4%.After the regulation implementation in Taizhou,the proportion of fatal head injuries decreased from 89%to 79%,remaining at a high level,which indicates that other measures in addition to helmet-wearing regulations should be *** to the results from Nanning,mandatory regulation worked more effectively than encouraged regulation in terms of reducing head ***:Mandatory helmet-wearing regulations are highly recommended to policymakers to reduce head injury among e-bike *** in addition to helmet-wearing regulation,*** law-abiding awareness and improving road infrastructure,should be considered to further protect e-bike riders.

关键词： e-bike safety accident analysis helmet-wearing regulation head injury

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