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341.
Taking the ' 6·13 ′ major gas explosion accident in Shiyan, Hubei Province, China as an example, three problems were studied in this work: (1)The determination of the volume of natural gas involved in the explosion; (2)The propagation process of shock wave inside the building and the damage evolution process of the accident-related building; (3)The overpressure and fragment injury to the person outside the building. Through the numerical simulation in ANSYS/LS-DYNA software, the volume of natural gas involved in the explosion is determined to be 10240 × 1400 × 400 cm (length × width × height) from three perspectives: the damage to the building, the distribution of overpressure inside the building, and the TNT equivalent of the explosion energy. The simulation results are in good line with the accident, which verifies the effectiveness of the scheme and the accuracy of the numerical model. Based on the reasonable filling scheme, the propagation process of shock waves inside the building, the damage evolution process of the building, and the injury ranges of overpressure and fragments outside the building are analyzed. It can be found that the propagation of shock waves in confined space is complex and variable. The explosion shock waves are first reflected and superimposed in the watercourse, resulting in pressure rise. At about 8ms, the shock waves rushed into the first-floor space of the building, and the maximum overpressure was about 0.56 MPa. At about 50 ms, the shock waves rushed into the second-floor space, and the maximum overpressure was about 0.139 MPa. The first and second-floor slabs and infilled walls were almost completely destroyed. The interior walls of the infilled walls are mainly collapsed, and the exterior walls are ejection around the building as the center. The peak displacement and peak velocity of the interior walls of each floor are about 15% of the exterior walls. The fragments which cause fragment injury mainly come from the retaining wall above the watercourse, the maximum velocity is about 89 m/s, and the maximum displacement is 8.9 m. The safety distance of fragment injury is about 8.8 m, while the safety distance of overpressure injury is about 4.6 m. The lethal distance of fragment injury is greater than that of overpressure injury. Compared with the distance between different damage levels of overpressure injury, the difference in fragment injury is small. Therefore, the safety assessment at the engineering level only needs to consider the safety distance of fragment injury. This study can provide suggestions for evaluating the damage of natural gas cloud explosions in confined spaces and is helpful for accident investigation and safety protection. 相似文献
342.
An E. coli SOS-EGFP biosensor which expresses enhanced green fluorescent protein as a reporter protein under the control of recA gene promoter in SOS response was constructed for detection of DNA damage and evaluation of DNA damaging chemicals. The chemicals that may cause substantial DNA damage will trigger SOS response in the constructed bacterial biosensor, and then the reporter egfp gene under the control of recA promoter is stimulated to express as a fluorescent protein, allowing fast and sensitive fluorescence detection. Interestingly, this biosensor can be simultaneously applied for evaluation of genotoxicity and cytotoxicity. The SOS-EGFP bacterial biosensor provides a sensitive, specific and simple method for detecting known and potential DNA damaging chemicals. 相似文献
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微塑料对鲫鱼生长、肝脏损伤和肠道微生物组成的影响 总被引:2,自引:2,他引:0
广泛存在于自然环境中的微塑料可能会危害水生生物的生长和健康,目前该方面的研究较少.以淡水杂食性鱼类鲫鱼作为研究对象,喂食不同微塑料浓度的鱼食进行为期30 d的食源暴露试验,分析微塑料对鲫鱼生长、肝脏损伤和肠道微生物组成的影响.结果表明,与对照组相比,各试验组中鲫鱼的身长没有明显变化,但低浓度组的鲫鱼体重显著增加,中浓度组和高浓度组的体重明显下降.低浓度组的鲫鱼肝脏组织基本正常,中浓度组和高浓度组的均出现了不同程度的肝组织异常现象,其中高浓度组的肝脏损伤最为严重.鲫鱼肠道中,变形菌门、梭杆菌门、厚壁菌门和拟杆菌门是门水平上的优势菌种,葡萄球菌属和劳尔氏菌属等致病菌在各试验组鲫鱼肠道中均有出现;α多样性结果表明高浓度组的鲫鱼肠道微生物菌群最为丰富;PCoA结果显示对照组和试验组的鲫鱼肠道微生物存在明显的聚类特征. 相似文献
346.
为了监测混凝土内部受拉开裂损伤,提出了混凝土内部拉应力监测压电智能骨料,并对其进行了动态拉应力标定试验研究。首先,制备4个压电智能骨料受拉试件,建立拉应力监测系统;其次,对压电智能骨料施加往复拉应力,标定得到其灵敏度系数;然后,对压电智能骨料试件施加单调荷载直至其受拉破坏,得到其抗拉强度及输出的电压信号,对比了破坏过程的实际与监测荷载。结果表明,往复荷载作用下,SA输出与输入荷载呈良好的线性关系,SA的灵敏度系数一致性较好;单调荷载作用下,各SA抗拉强度均高于混凝土抗拉强度。综上,压电智能骨料有潜力应用于混凝土内部的拉应力监测。 相似文献
347.
秦岭大巴山地区山地灾害及减灾对策 总被引:4,自引:0,他引:4
本文在论述秦岭大巴山地区山地灾害类型特征、分布规律及综合分析致灾成因的基础上,提出了五条具体的减灾对策。 相似文献
348.
工程冻害主要表现为;基土在冻融过程中.结构物或基础的各种冻胀及融沉破坏;江河水库等的冻结冰盖板对建筑物的静冰推力及动压力作用;工程材料的冻融损伤破坏。而冻害的实质是冻土(或冰)与结构物之间相互作用和相互适应的问题.本文从工程冻害防治的角度出发,分别对抗冻胀设计,冻害预测预报和防治措施优化等几方面,进行了初步分析与探讨. 相似文献
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