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Experimental and numerical studies of the blast-induced overbreak and underbreak in underground roadways

Underground Space 2023年第1期8卷 61-79页

作者： Zhixian Hong Ming Tao Xuejiao Cui chengqing wu Mingsheng Zhao School of Resources and Safety Engineering Central South UniversityChangshaHunan 410083China School of Civil and Environmental Engineering the University of Technology SydneySydneyNSW 2007Australia Poly Xinlian Blasting Engineering Group Co. Ltd.GuiyangGuizhou 550002China

Overbreak and underbreak are the crucial problems during the blasting excavation of underground tunnels owing to their effects on the construction costs and operational safety.A critical challenge facing overbreak and underbreak control is the difficulty in developing guidelines with respect to various and complex engineering *** this study,a series of field measurements of overbreak and underbreak using the Focus^(S)150 laser scanner were performed in a deep roadway of the Kaiyang phosphate mine,*** distri-bution and extent of the overbreak and underbreak surrounding the roadway contour were accurately analyzed in accordance with the collected point cloud ***,a simplified three-dimensional model was established to simulate the blasting excavation of pre-stressed roadway using the explicit dynamic analysis code LS-DYNA.A comparison of numerical and measurement results revealed that the proposed model was a reliable tool to simulate the overbreak and underbreak induced by blasting ***,the influ-ences of uncontrollable geological factors such as in situ stress conditions and controllable blasting factors including contour hole spac-ing(S),charge concentration(b)and decoupled coefficient(f)as well as stemming were further numerically *** simulation results indicated that the lateral pressure coefficient significantly affected the distribution pattern of the overbreak and underbreak,while the stress magnitude contributed to their ***,a comparison of the simulation findings and the field measurement data indicated that the minimal extents of the overbreak and underbreak corresponding the optimal contour blasting results were obtained at S=0.70 m,b=0.9 kg/m and f=2.5,***,the contour blastholes stemmed with sand created smaller damage to the periphery rock mass of roadway and enhanced the utilization efficiency of explosive *** research findings of this study pro-vide impo

关键词： Underground roadway Overbreak Underbreak Blasting excavation 3D laser scanning Numerical modeling

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FRP Retrofitted RC Slabs Using Finite Difference Model

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Transactions of Tianjin University 2008年第5期14卷 344-347页

作者： wu chengqing OEHLERS DericJohn WHITTAKER Andrew School of Civil Environmental and Mining Engineering The University of Adelaide North Terrace SA 5005 Australia Department of Civil Structural and Environmental Engineering State University of New York at Buffalo Buffalo NY 14260 USA

Current guidelines recommend using single-degree-of-freedom(SDOF) method for dynamic analysis of reinforced concretec (RC) structures against blast loads, which is not suitable for retrofitted members. Thus, a finite difference procedure developed in another study was used to accurately and efficiently analyze the dynamic response of fibre reinforced polymer (FRP) plated members under blast loads. It can accommodate changes in the mechanical properties of a member's cross section along its length and through its depth in each time step, making it possible to directly incorporate both strain rate effects (which will vary along the length and depth of a member) and non-uniform member loading to solve the partial differential equation of motion. The accuracy of the proposed method was validated in part using data from field blast testing. The finite difference procedure is implemented easily and enables accurate predictions of FRP-plated-member response.

关键词： finite difference analysis blast loads retrofit slab

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Numerical Analysis of Structural Progressive Collapse to Blast Loads

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Transactions of Tianjin University 2006年第B09期12卷 31-34页

作者： HAO Hong wu chengqing LI Zhongxian ABDULLAH A K School of Civil and Resource Engineering University of Western Australia Australia School of Civil and Environmental Engineering University of Adelaide Australia School of Civil Engineering Tianjin University Tianjin 300072 China

After the progressive collapse of Ronan Point apartment in UK in 1968, intensive research effort had been spent on developing guidelines for design of new or strengthening the existing structures to prevent progressive collapse. However, only very few building design codes provide some rather general guidance, no detailed design requirement is given. Progressive collapse of the Alfred P. Murrah Federal building in Oklahoma City and the World Trade Centre (WTC) sparked again tremendous research interest on progressive collapse of structures. Recently, US Department of Defence (DoD) and US General Service Administration (GSA) issued guidelines for structure progressive collapse analysis. These two guidelines are most commonly used, but their accuracy is not known. This paper presents numerical analysis of progressive collapse of an example frame structure to blast loads. The DoD and GSA procedures are also used to analyse the same example structure. Numerical results are compared and discussed. The accuracy and the applicability of the two design guidelines are evaluated.

关键词： progressive collapse blast loads damage mechanics numerical

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Dynamic response of water-rich tunnel subjected to plane P wave considering excavation induced damage zone

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Underground Space 2024年第2期15卷 113-130页

作者： Gongliang Xiang Ming Tao Rui Zhao Huatao Zhao Muhammad Burhan Memon chengqing wu School of Resources and Safety Engineering Central South UniversityChangsha 410083China School of Geoscience and Technology Southwest Petroleum UniversityChengdu 610500China School of Civil and Environmental Engineering University of Technology SydneyNSW 2007Australia

The stability analysis of a deep buried tunnel subjected to dynamic disturbance is an important *** this study,the transient response has been obtained by establishing a water-rich tunnel model considering excavation damage zone(EDZ).Based on Biot’s two-phase dynamic theory and wave function expansion method,the analytical solution of dynamic response around the water-rich tunnel containing EDZ subjected to P wave is ***,Fourier transform and Duhamel’s integral technique is introduced to calculate the transient response,and the equivalent blasting curve is adopted to input excitation *** dimensionless parameters thickness N and shear modulus ratio lare defined to characterize the degree of damage in the surrounding rock,investigating the influencing factors,such as the parameters and the incident source *** results indicate that the dynamic stress concentration factor(DSCF)gradually decreases as the dimensionless parameters ***,it is observed that the DSCF is more sensitive to changes in the thickness parameter ***,the influence of the waveform parameters has been taken into account in the analysis of transient response,and the stress state and transfer process in each time stage of the EDZ are *** study establishes a theoretical foundation for comprehending the mechanical behavior and support design considerations associated with a deep-buried water-rich tunnel containing EDZ.

关键词： Water-rich tunnel Two-phase dynamic theory Wave scattering Transient response Dynamic stress concentration

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Retrofitting of RC Slabs Against Explosive Loads

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Transactions of Tianjin University 2006年第B09期12卷 88-93页

作者： wu chengqing 0EHLERS Deric John XIA Shaohua School of Civil and Environmental Engineering The University of Adelaide Australia Defence Science and Technological Organization Australia

With the increase of terrorist bomb attacks on buildings, there is a need to develop advanced retrofitting techniques to strengthen structures against blast loads. Currently, several guidelines including an Australian version for retrofitting reinforced concrete (RC) structures are available for the design of retrofitting systems against seismic and monotonic loads using steel or fibre reinforced polymer (FRP) plates that can be either adhesively bonded to the surface or near surface mounted to the concrete cover. However, none of these guidelines provide advice suitable for retrofitting structures subjected to blast loads. In this paper, numerical models are used to simulate the performance of retrofitted RC slabs subjected to blast loads. Airblast pressure distributions on the surface of the slabs estimated in a previous study are used as input in the analysis. A material damage model developed previously for concrete and an elastoplastic model for steel bars are employed in this research for modelling reinforced concrete behaviour due to explosive loads. The material models and blast loading are coded into a finite element computer program LS-DYNA3D to do the analysis. With the numerical model, parametric studies are conducted to investigate RC slabs retrofitted by either externally bonded or near-surface mounted plates or GFRP sheets subjected to blast loads. Discussion is made on the effectiveness of the retrofitting system for RC slabs against blast loads.

关键词： retrofit explosion fibre reinforced polymer slab

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Seismic response of tunnel near fault fracture zone under incident SV waves

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Underground Space 2021年第6期6卷 695-708页

作者： Zhongxian Liu Jiaqiao Liu Qiang Pei Haitao Yu Chengcheng Li chengqing wu Tianjin Key Laboratory of Soft Soil Properties and Engineering Environment Tianjin Chengjian UniversityTianjin 300384China Research&Development Center of Civil Engineering Technology Dalian UniversityDalian 116622China Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji UniversityShanghai 200092China School of Civil and Environmental Engineering University of Technology SydneyNSWAustralia

This study investigated the impact of a non-causative fault on the dynamic response of a nearby lined tunnel under the incidence of plane SV waves using the indirect boundary element *** effects of several critical parameters,such as the incident frequency,the inclination degree of the fault,the distance between the fault and the tunnel on the hoop stress of the lined inner and outer walls,were explored *** numerical results indicated that the non-causative fault could significantly change the hoop stress distribution of inner and outer surfaces of the *** general,for the vertically incident seismic waves,when the tunnel was located in the foot wall(under the fault),the hoop stress within the tunnel was significantly greater than that of the tunnels in the non-fault half space,with an amplification factor of up to 117%.The amplification effect became more pronounced as the fault dip angle ***,when the tunnel was located in the hanging wall(above the fault),the non-causative fault could produce a significant shielding effect on the dynamic response of the tunnel under high frequency wave incidence,with the reduction of hoop stress being up to 81%.For lowfrequency waves,though,the fault could lead to an increase of the hoop stress of the tunnel of up to 152%.The research results will provide a reference for the seismic design and safety protection of underground structures in non-causative fault sites.

关键词： Non-causative fault Indirect boundary element method Fault fracture zone Lined tunnel

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Numerical Simulations of the Performance of Steel Guardrails Under Vehicle Impact

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Transactions of Tianjin University 2008年第5期14卷 318-323页

作者： HAO Hong DEEKS J Andrew wu chengqing School of Civil and Resource Engineering the University of Western Australia 35 Stirling Highway Crawley WA 6009 Australia School of Civil Environmental and Mining Engineering the University of Adelaide North Terrace SA5005 Australia

Road side barriers are constructed to protect passengers and contain vehicles when a vehicle crashes into a barrier. In general, full-scale crash testing needs to be carried out if a geometrically and structurally equivalent barrier has not previously been proven to meet the requirements of containing the vehicle and dissipating sufficient impact energy for passenger protection. As full-scale crash testing is very expensive, the number of data that can be measured in a test is usually limited, and it may not always be possible to obtain good quality measurements in such a test, a reliable and efficient numerical simulation of crash testing is therefore very useful. This paper presents finite element simulations of a 3-rail steel road traffic barrier under vehicle impact. The performance levels defined in Australian Standards AS5100 Clause 10.5 for these barriers are checked. The numerical simulations show that the barrier is able to meet low performance levels. However, the maximum deceleration is higher than the acceptable limit for passenger protection. If present, a kerb launches the vehicles into the barrier, allowing for the possibility of overriding the barrier under certain circumstances, but it redirects the vehicle and reduces the incident angle, which reduces impact force on the barrier. Further investigation into all common kerb profiles on roads should be carried out, as only one kerb profile is investigated in this study.

关键词： vehicle impact steel barrier kerb performance level vehicle containment passenger protection

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Mitigation of Blast Effects on Aluminum Foam Protected Masonry Walls

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Transactions of Tianjin University 2008年第B10期14卷 558-562页

作者： GRIFFITH Mike School of Civil Environmental and Mining Engineering The University of Adelaide SA 5005 Australia

Terrorist attacks using improvised explosive devices （IED） can result in unreinforced masonry （URM） wall collapse. Protecting URM wall from IED attack is very complicated. An effective solution to mitigate blast effects on URM wall is to retrofit URM wails with metallic foam sheets to absorb blast energy. However, mitigation of blast effects on metallic foam protected URM walls is currently in their infancy in the world. In this paper, numerical models are used to simulate the per- formance of aluminum foam protected URM walls subjected to blast loads. A distinctive model, in which mortar and brick units of masonry are discritized individually, is used to model the perform- ance of masonry and the contact between the masonry and steel face-sheet of aluminum foam is modelled using the interface element model. The aluminum foam is modelled by a nonlinear elas- toplastic material model. The material models for masonry, aluminum foam and interface are then coded into a finite element program LS-DYNA3D to perform the numerical calculations of response and damage of aluminum foam protected URM walls under airblast loads. Discussion is made on the effectiveness of the aluminum foam protected system for URM wall against blast loads.

关键词： mitigation blast loads aluminium foam masonry

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碳纤维加固钢筋混凝土板的爆炸试验研究

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混凝土 2007年第11期 65-68,72页

作者：孙文彬 chengqing wu 淮阴工学院土木工程系江苏淮安223001 School of Civil and Environmental Engineering University of Adelaide North Terrance SA 5005 Australia

粘贴或包裹碳纤维布加固钢筋混凝土结构不仅得到了广泛研究,而且已被成熟应用于工程实践。在混凝土保护层嵌入碳纤维(或玻璃纤维)条加固钢筋混凝土结构,具有不改变构件的截面尺寸和外观,不影响建筑效果等优点,正在成为一种新的加固技术... 详细信息

粘贴或包裹碳纤维布加固钢筋混凝土结构不仅得到了广泛研究,而且已被成熟应用于工程实践。在混凝土保护层嵌入碳纤维(或玻璃纤维)条加固钢筋混凝土结构,具有不改变构件的截面尺寸和外观,不影响建筑效果等优点,正在成为一种新的加固技术,尤其适用于公共建筑、经典建筑的加固。选择结构中常用的钢筋混凝土简支单向板为试验对象,在板的保护层分别嵌入6条厚度1.4mm宽度20mm的碳纤维布,研究试件的爆炸响应以及爆炸中所表现的破坏特征,尤其是嵌入的碳纤维的破坏,研究碳纤维在钢筋混凝土板爆炸动力响应中的作用。试验结果证明,保护层嵌入碳纤维(CFRP)可以有效地用于加固遭受爆炸荷载的钢筋混凝土构件和结构。

关键词：碳纤维加固钢筋混凝土板爆炸

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方形中空夹层钢管超高性能钢纤维混凝土柱抗爆性能数值模拟与实验验证

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振动与冲击 2017年第1期36卷 45-54页

作者：徐慎春刘中宪吴成清天津大学建工学院天津300372 天津城建大学天津市土木建筑结构防护与加固重点实验室天津300384 天津城建大学与悉尼科技大学防灾减灾联合研究中心天津300384

建立了爆炸荷载作用下方形中空夹层钢管超高性能钢纤维混凝土(Ultra-High Performance Steel Fiber Reinforced Concrete Filled Double Skin Steel Tube,UHPSFRCFDST)柱动态响应及其损伤破坏三维有限元数值模型。首先通过模拟结果与爆... 详细信息

建立了爆炸荷载作用下方形中空夹层钢管超高性能钢纤维混凝土(Ultra-High Performance Steel Fiber Reinforced Concrete Filled Double Skin Steel Tube,UHPSFRCFDST)柱动态响应及其损伤破坏三维有限元数值模型。首先通过模拟结果与爆炸破坏试验结果的对比分析,验证了数值模型和计算方法的有效性。进而运用参数化分析方法,研究了空心率、含钢率、内、外层钢管厚度及其强度等关键参数对UHPSFRCFDST柱抗爆性能的影响。研究结果表明,UHPSFRCFDST柱具有优越的抗爆性能,所建立的三维有限元模型能够有效地分析UHPSFRCFDST柱在爆炸荷载作用下的动态响应及其损伤破坏;在一定范围内减小空心率及提高外层钢管强度可有效提升UHPSFRCFDST柱抗爆性能;提高含钢率、减小内、外层钢管高厚比均能够显著提升UHPSFRCDST柱抗爆性能;内层钢管强度对UHPSFRCFDST柱的抗爆性能影响并不明显。

关键词：中空夹层钢管超高性能钢纤维混凝土柱爆炸荷载动态响应破坏模式有限元模型

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