Mechanical response and stability analysis of rock mass in high geostress underground powerhouse caverns subjected to excavation

To investigate the stability of rock mass in high geostress underground powerhouse caverns subjected to excavation,a microseismic(MS)monitoring system was established and the discrete element method(DEM)-based numerical simulation was carried out.The tempo-spatial damage characteristics of rock mass were analyzed.The evolution laws of MS source parameters during the formation of a rock collapse controlled by high geostress and geological structure were investigated.Additionally,a three-dimensional DEM model of the underground powerhouse caverns was built to reveal the deformation characteristics of rock mass.The results indicated that the MS events induced by excavation of high geostress underground powerhouse caverns occurred frequently.The large-stake crown of the main powerhouse was the main damage area.Prior to the rock collapse,the MS event count and accumulated energy release increased rapidly,while the apparent stress sharply increased and then decreased.The amount and proportion of shear and mixed MS events remarkably increased.The maximum displacement was generally located near the spandrel areas.The MS monitoring data and numerical simulation were in good agreement,which can provide significant references for damage evaluation and disaster forecasting in high geostress underground powerhouse caverns.

超声断层扫描法检测混凝土内部缺陷技术研究

目前,建筑工程混凝土结构质量检测中的常用方法包括超声波法、雷达法、冲击回波法、红外热像法和钻芯法,论文介绍了这些检测方法的原理及缺点,详细介绍了断层扫描检测技术的原理及应用过程,旨在推广断层扫描检测技术在工程领域中的应用。

“家校卫融合”模式对深圳市光明区学生伤害结果的影响

目的了解“家校卫融合”模式对中小学生伤害发生和结果的影响,为制定中小学生伤害预防与干预政策提供科学依据。方法采用分层整群抽样方法,抽取深圳市光明区已采用“家校卫融合”模式运作的3所哨点学校2019学年(2019年9月1日―2020年8月31日)11439名中小学生,与干预模式实施前的2014学年(2014年9月1日―2015年8月31日)3所学校8056名中小学生的伤害数据作为对照进行比较,采用SPSS 21.0软件进行统计分析,定性资料采用频率描述,组间比较使用χ^(2)检验,等级资料组间比较使用非参数检验。结果2019学年光明区学校报告年平均伤害发生率为19.86%,男生伤害发生率为24.54%,女生伤害发生率为13.89%;小学伤害发生率最高,为35.01%;伤害发生时最主要的状态是活动娱乐/玩耍/休闲,占比60.40%;伤害类型主要表现为跌倒/坠落伤、钝器伤,分别占比57.39%、30.85%;伤害部位以膝部、头部为主,分别占比19.76%、15.76%;挫伤、擦伤是最主要的伤害后果,占比64.13%;与2014学年相比,2019学年学生轻度伤害比例提升,中度和重度比例下降,差异具有统计学意义(Z=-51.88,P<0.001)。结论“家校卫融合”模式促进了家庭、学校、医疗卫生机构的在学校卫生工作各方面的有效协同,提高了中小学生伤害监测的敏感度。