Site correction of ground motion in Fujian area

On the basis of the interpretation of the highresolution satellite remote sensing images, in combination with the data of engineering geological exploration and shear-wave velocity testing, the site category-zoning map of FJ area with the scale of 1：200,000 is generated according to the site classification standard of ＂Code for Seismic design of Buildings＂ of China （GB50011 2010）. By the method of Probabilistic Seismic Hazard Analysis, we obtain bedrock seismic ground motion parameters of five recurrent periods （50, 200, 500, 1000, and 2500 a） of FJ area. By using the 617 typical soil layer structures of the site classifications in FJ area, we build seismic response models of soil layers and make seismic response analysis, then obtain the statistic sample space of site amplification factors, which possess reasonable distribution and sufficient data. Considering the distribution characteristics of The Quaternary Strata in FJ area, according to the statistic zoning （mountains and coastal areas respectively） and site classifications as well as the level of bedrock importing ground motion, the site magnification-factors of ground motion in FJ area are obtained by classification statistics.

Seismic hazard analysis of Tianjin area based on strong ground motion prediction

Taking Tianjin as an example, this paper proposed a methodology and process for evaluating near-fault strong ground motions from future earthquakes to mitigate earthquake damage for the metropolitan area and important engineering structures. The result of strong ground motion was predicted for Tianjin main faults by the hybrid method which mainly con- sists of 3D finite difference method and stochastic Green＇s function. Simulation is performed for 3D structures of Tianjin re- gion and characterized asperity models. The characterized asperity model describing source heterogeneity is introduced fol- lowing the fault information from the project of Tianjin Active Faults and Seismic Hazard Assessment. We simulated the worst case that two earthquakes separately occur. The results indicate that the fault position, rupture process and the sedi- mentary deposits of the basin significantly affect amplification of the simulated ground motion. Our results also demonstrate the possibility of practical simulating wave propagation including basin induced surface waves in broad frequency-band, for seismic hazard analysis near the fault from future earthquakes in urbanized areas.

Preliminary Study on Dynamic Changes of Insect Communities in Airport Ground Cover Areas in Different Weather Conditions

[Objectives]This study was conducted to investigate insect activity rhythms in airport ground cover areas,and provide guidance for insect control and bird strike prevention.[Methods]The daily rhythm of insects in the northern area of the airport was studied,and their activity rhythms and characteristics under different weather conditions were analyzed.[Results]In rainy days,the insect number in the three sample areas was low.In cloudy days,insect activity was relatively stable,and insect number was consistent in the morning and evening,and maintained in a stable range,while in sunny weather,insect activity was increased,and the number changed greatly with time.For a single tussock plant growth area,the number of insects was at a relatively low level under rainy weather.In fine weather,the peak period of insect activity was between 10:00-11:00 and 14:00-15:00.[Conclusions]This study can provide a reference for the formulation of safe flight departure time.

Assessment of seismic ground motion amplification and liquefaction at a volcanic area characterized by residual soils

A seismic hazard was assessed related to site effects at Abbadia San Salvatore, central Italy, on the Mt. Amiata slopes, an ancient volcanic area characterized by residual soils(thick layers of loose to dense sands originated from weathering of the trachydacitic lavas). The seismic ground amplification and soil liquefaction related to these layers were recognized as the major seismic hazards for the area.Geological, geophysical, and geotechnical surveys were carried out on the volcanic rocks. The Horizontal-to-Vertical Spectral Ratio(HVSR) analysis of 252 noise measurements and 29 shear-wave velocity models of the subsoil allowed a seismic microzonation of the studied area, distinguished by thick weathered volcanic sands and shear-wave impedance contrast with respect to the seismic bedrock(volcanic bedrock). The differentiation of classified zones allowed recognition of areas characterized by residual(almost undisturbed) soils from those with soils probably affected by flowing water. The analysis of hazards revealed that peak acceleration by seismic amplification of ground motion exceeded the value set by the national rules(0.175 g) in a restricted area of the zone characterized by the most perturbed soils(Zone D);the potential occurrence of soil liquefaction was also greater in this zone. Finally, the study showed potential high hazards due to site effects of the volcanic mountainous area characterized by residual soils as opposed to an alluvial plain formed by volcanic debris where these effects have generally been more recognized.

Ground stability of new surface buildings erected on site above worked-out area

The subsided area caused by mining is expanding gradually in coal mining areas. In order to occupy less or no farmland, many mining areas are constructing or intend to erect new buildings (structures) on the ground sites above the worked-out areas. The long-term safety of the new buildings is of great importance. This matter should be, therefore, handled with great care. Following an analysis of the different conditions of the worked-out areas, and the characteristics of the failure of different types of worked-out areas and their overlying strata, the cause for the occurrence of residual deformation of the surface above the worked-out area was explained. The techniques for (evaluating) the stability of ground site for erecting new buildings above worked-out area, and the technical measures for protecting such buildings were proposed. The ground stability evaluation techniques were introduced by reference to specific cases.

基于随机森林算法的天津市滨海地区地面沉降模拟

地面沉降的监测与预测,对于保障城市安全和社会可持续发展具有重要意义和现实价值。利用随机森林机器学习模型预测了天津市滨海地区的地面沉降量空间分布,并评估了模型的性能和变量的重要性。基于2020年天津市滨海新区局部地区的地面沉降量、含水层岩性、含水组水位差、水文地质参数等数据来训练和验证随机森林模型。结果表明:随机森林模型能够较好地拟合和预测地面沉降量(R^(2)=0.98,RMSE=0.52 mm);影响地面沉降量最重要的因素是水位差,其次是含水层的岩性(砂-黏比值),最后是相关水文地质参数。上述结果与传统上太沙基原理基本吻合,进一步验证了模型的正确性和可预测性。本研究采用了空间分布数据来训练随机森林模型;根据物理机制,选取了重要控制因素来开展分析;评估了控制因素的重要性程度,并指出了研究的局限性和未来的研究方向,为利用随机森林模型快速有效预测地面沉降提供了重要参考和启示。

我国黄土高原地区地震动衰减关系研究的若干进展

地震动的衰减关系是指地震动随震级、距离和场地条件等变化的经验关系,近年来在我国亦被称为地震动预测方程,是估计地震动及其影响场的主要方法之一,在地震区划和重大工程场地地震安全性评价中被广泛应用。黄土是一种特殊土,在我国广泛分布。我国黄土高原地区地质构造复杂,新构造活动强烈,中强地震频发,地震动的衰减关系有其特殊性,总结我国黄土高原地区地震动衰减关系的研究成果对促进黄土高原地区抗震研究有重要意义。在简要介绍国内外地震动衰减关系研究的基础上,全面系统地总结我国学者在黄土高原地区的地震烈度衰减关系,基岩和土层场地地震动峰值加速度、峰值速度、峰值位移以及反应谱衰减关系方面的研究成果;评述和讨论在黄土覆盖地区地震动衰减研究领域存在的问题和今后的研究方向。文章的研究工作对从事黄土高原地区地震工程研究的科技人员有重要参考价值。

西南山区铁路客运专线隧道底鼓病害变形监测研究

西南山区铁路客运专线具有高桥隧比、沿线地质条件复杂恶劣等特征,在建设和运营过程中易出现各类工程病害。文章基于某隧道底鼓变形病害,设计并开展包含围岩变形、仰拱受力和道床板沉降变形3个监测指标的隧道变形监测方案。通过对监测数据进行分析,获取隧道和围岩受力变形的演化规律,据此提出后续加密轨道几何形位静态、动态检测和衬砌结构贯通裂缝观测、实施列车降速运行等处理措施。相关研究可为该客运专线的安全运营提供有力保障,同时为类似工程隧道病害的监测和整治工作提供有益参考。

长春市羊草沟矿区地面塌陷现状及防治对策

随着煤炭资源的开发,曾经隐于地下的宝藏和财富得以显现,然而开采过程会伴随着严重的地面塌陷问题,对土地资源及地区经济发展带来了深远的负面影响。本文聚焦长春市羊草沟矿区,对其地面塌陷问题进行了细致研究。通过分析该矿区塌陷的分布特点、发育特征以及所引发的一系列问题,系统剖析了导致地面塌陷的多种因素,并基于此提出了坚持政策先行、加强监测预警、开展工程治理、土地利用调整等针对性的预防与治理对策,作为羊草沟及类似矿区矿山地质环境治理工作的参考依据。

铁路地质灾害勘察识别与监测预警

地质灾害对铁路建设、安全运营构成了极大威胁,“天空地”一体化综合勘察技术有效解决了地质灾害勘察识别难题。“天”基多源立体卫星遥感技术实现艰险复杂山区地质灾害的大范围精准判识,长时序InSAR与高精度GPS实现高陡岸坡的稳定性监测分析;“空”基真实感大场景、机载倾斜摄影和机载LiDAR扫描技术实现高植被覆盖区隐蔽性地质灾害判识;“地”基三维立体勘探技术获取岩土体结构、属性、参数;共同构建沟谷山地灾害链风险评价方案,为建设工程合理选址和工程设置提供依据。介绍地质灾害监测预警的方法、内容、技术和预警模型,对监测预警技术发展方向进行展望。

空地一体遥感技术在轨道交通安全保护区巡查中的应用

随着城市轨道交通建设的不断发展,轨道交通沿线安全保护区巡查工作的范围越来越大,内容越来越多,区域内的情况越来越复杂。针对存在的问题,本文构建了一套空地一体的遥感综合监测体系,在巡查工作中引入航空摄影测量、低空无人机监测、车载全景扫描、定点实时监控等多种遥感监测技术及DSM差分计算、深度学习智能识别等多种数据处理技术,并以上海为例开展应用实践。结果表明,本文方法具有可行性,对建立全覆盖、高频次、智能化的巡查模式有参考借鉴价值。

某萤石矿老空区水害及稳定性风险综合评估研究

为掌握河南某整合萤石矿老空区体量规模、富水性、稳定性等基本情况,开展该矿黄土岗采区富水情况物探及稳定性评估研究。通过理论分析与地面物探相结合方法,进行老空区富水情况研究;通过现场调查,采用经验公式验算分析老空区稳定性。研究结果表明:黄土岗采区K_(2)、K_(3)矿体老空区共圈定8个富水异常区,其总面积21 074.22 m^(2),总体积358 902.3 m^(3);各个异常区在空间上分布较为分散、孤立,老空区属性为单一采空区,规模为小型,顶板稳定性良好,安全等级为安全级,综合评定老空区不构成重大事故隐患。在此基础上给出合理的老空区治理建议,为老空区的水害防治提供了可靠依据,也为相似条件下矿山的隐蔽致灾因素调查提供参考。

岩溶区土洞对自由场地震动放大效应的影响

岩溶区土洞的发育改变了自由场的地震工程地质条件,从而影响了地表地震动力响应结果。为探讨岩溶区土洞对地震动场地效应的影响,设计并构建典型岩溶区土洞自由场地,利用有限差分法开展了不同地震动输入条件下的含土洞场地的地震反应分析。通过与自由场地震反应分析结果对比可知:(1)土洞的存在阻碍了地震波的传播,从而使得地表中心点峰值加速度显著减小,随着输入地震动峰值增大,土洞的影响范围增大,土洞附近地表峰值加速度呈现出先增大后减小,最后逐渐趋向于自由场;(2)土洞的存在使场地的竖向位移增大,且随输入加速度峰值增大而增大、对水平向峰值位移影响较小;(3)加速度放大系数总体呈现出先增大后减小的趋势,随输入加速度峰值增大而减小;(4)土洞的存在使得反应谱的短周期幅值减小,这种减小幅度受输入地震动峰值的影响不明显。

高密度环境下住区设计中的次级地面策略研究

在高密度环境下,借助空中连廊、空中平台来创造公共空间是近期住宅设计中频繁出现的设计策略,又被称为次级地面策略。通过梳理次级地面从乌托邦设想发展至实践策略的历程,分析得出次级地面需要面对的“本体性问题”和“城市性问题”。进一步讨论了次级地面实践案例中对两个问题的回应方式,归纳出三种次级地面策略的应用方式,以期丰富住区公共空间设计的思路和方法。

山丘区地表基质空间异质性特征及其对植被生态影响

地表基质是地球表层孕育和支撑森林、草原、水、湿地等各类自然资源的基础物质,受地球关键带空间结构、元素特征等因素的影响,山丘区地表基质呈现明显的空间异质性特征,并显著影响着所属植被的空间分布和生态演化。研究地表基质空间异质性特征及其对植被生态的影响机理,对于进一步认识地球关键带结构及地表作用规律,支撑国土空间生态环境修复具有重要意义。以宁波山丘区地表基质为研究对象,采取剖面研究和样品测试的方法,从地表基质空间结构和元素特征角度,对花岗岩、流纹岩和玄武岩3类典型地表基质空间异质性进行了分析。研究发现,花岗岩类具有土质粗、透水性强等特点,流纹岩类具有土质较粗、浅表透气好等特点,玄武岩类具有土质细、通气性差等特点。此外,花岗岩类主量和微量元素较缺乏,流纹岩类富含Mo和Zn,玄武岩类富含Fe、Mg、Co、Cu、Zn等元素,且玄武岩CIA值明显高于花岗岩和流纹岩。结果表明,山丘区地表基质空间异质性主要受基岩的结构和元素组成影响,并对植被生长产生明显的生态效应。地表基质的空间结构主要影响水分的分布与运移,元素特征影响着养分的分布状况,由此引起的水分和养分的空间分布和丰度差异直接影响着植被生长。

浅埋煤层过沟开采覆岩破坏特征及水害防治技术研究

黄土沟壑区溃水水害是浅埋煤层开采的主要灾害之一。安山煤矿煤层埋藏浅、局部沟道所在区域5-2煤层顶板距离地表不足30 m,为了解决黄土沟壑区工作面过沟开采可能遇到的水害问题,通过数值模拟的手段研究了工作面过沟开采时的覆岩破坏特征,提出了研究区过沟开采时冒裂安全性分区标准,并基于分区结果提出了预防工作面过沟开采发生溃水水害事故的防治技术,过沟开采防治技术包括采前筑坝截流引流,采后工作面地表裂缝修复等,并在工作面过沟开采区域成功地进行了防治应用,应用结果表明,防治技术能够有效预防工作面过沟开采溃水水害。研究成果对榆神矿区工作面安全、绿色高效过沟开采具有一定的借鉴意义。

面向环保接地施工的杆塔分支式外延接地网接地特性研究

低碳环保已成为国家的战略和政策导向,输电杆塔在降阻施工时,常采用敷设长距离外延接地极方式接地,造成资源浪费、环境破坏等问题。针对杆塔接地施工环境的复杂性与施工面积的有限性,文中提出输电线路杆塔分支式外延接地网散流降阻结构,实现了接地降阻施工的低碳环保。首先,仿真计算单根外延接地极的有效降阻长度;然后,研究了土壤电阻率、入地电流频率对单分支式和多分支式外延接地网降阻特性的影响规律;最后,分析了不平衡分支式外延接地网的散流特性。结果表明:相比于传统方框带射线型接地网,分支接地极结构比例为1/3的单分支式外延接地网具备更好的降阻特性,并且三分支式外延接地网的接地施工面积更小,不平衡分支式外延接地网有助于进一步降低主接地网的散流密度。

阿尔金地区“天空地深”一体化找矿勘查评价体系应用实践——以阿亚克-瓦石峡南为例

阿尔金地区属中高山地形,地势陡峭,海拔一般在2 000 m以上,比高大于300 m。高山区切割较深,地表基本无植被,基岩裸露较好。长期以来,因极端恶劣的交通条件,矿产勘查开发受到严重制约。新一轮找矿突破行动主攻昆仑-阿尔金,对高寒山区、工作空白区探索绿色、低成本、高效率的勘查评价技术方法势在必行,在此背景下逐渐形成适应阿尔金地区“天空地深”一体化找矿勘查评价体系[1]。该体系中“天”指遥感技术应用,即采用高清卫片结合谷歌地图等影像资料识别解译伟晶岩脉,圈定伟晶岩脉集中分布区域;“空”指无人机技术应用,即采用航空摄影及三维建模对地表伟晶岩延伸情况进行圈定;“地”指地面传统找矿手段应用,即采用路线地质调查、填图、槽探及采样分析等手段对无人机圈定的伟晶岩脉进行地面查证,圈定含矿伟晶岩脉;“深”指深部钻探手段应用,即采用便携式钻机了解含矿伟晶岩脉深部延伸及品位变化情况。该体系的应用可精准锁定找矿靶区,圈定矿(化)体,对矿区进行勘查评价,极大提高了找矿勘查效率,缩短找矿周期,在地形切割强烈的阿尔金地区值得广泛运用。