秦皇岛中央河畔结构设计

高层建筑结构大面积地库设计时,概念设计的重要性,控制单体建筑规则性,避免超限设计;地库与主楼相连对主楼的影响,对地基基础的分析,通过设置后浇带等手段解决高低层的沉降问题。介绍大面积地库的裂缝预防措施等设计方法,最终实现结构设计。     

外加剂对硫氧镁水泥的改性作用

通过对硫氧镁水泥材料进行改性,使其试块在空气中性质稳定,同时获得具有较高的抗压强度。为了对比外加剂对硫氧镁水泥试块抗水性能的影响,试块水养护和空气养护同时进行,并测试3 d、7 d、28 d龄期的抗压强度,试块空气养护28 d后转置入水中养护,取得水对硫氧镁水泥的软化影响(K)。对龄期为28 d样品进行扫描电子显微镜(SEM)微观形貌分析和X-射线衍射(XRD)物相分析。实验结果显示两种外加剂能够有效提高硫氧镁水泥材料的稳定性和抗压性能,同时对提高材料抗水性能有一定的效果。     

Comparison of 2D versus 3D modeling approaches for the analysis of the concrete faced rock‐fill Cokal Dam

This paper's primary purpose is to compare the 2D and 3D analysis methodologies in investigating the performance of a concrete faced rock‐fill dams under dynamic loading conditions. The state of stress on the face plate was obtained in both cases using a total strain based crack model to predict the spreading of cracks on the plate and the corresponding crack widths. Results of the 2D and 3D analyses agree well. Although significantly more demanding, 3D analyses have the advantage of predicting the following: (i) the opening of the vertical construction joints; (ii) the cracking at the valley sides; and (iii) the crushing of the plate during the seismic action. During the earthquake loading, the cracking predicted at the base of the face plate after the impounding spread significantly towards the crest of the dam; however, the crack widths are obtained relatively small. Crushing of the face plates at the construction joints is the primary cause of the large scale cracking predicted on the face plate for high intensity earthquakes. Earthquake induced permanent deformation of the fill increases the compressive stresses on the face plate, thereby reducing the minute cracking on the plate. However, this effect also leads to significant increases in the residual openings at the construction joints and at the plinth level. Copyright © 2013 John Wiley & Sons, Ltd.     

断裂（带）对采空塌陷及地裂缝地质灾害的影响——以山东新泰市河山子村为例

新泰市河山子村东部较大范围集中发生地面裂缝和房屋裂缝,裂缝点沿莲花山断层呈线状分布,所在地段远离采空区,基岩裸露,经调查分析,排除了岩溶塌陷、区域构造活动引发的可能,结合有关研究认为,断层带的存在使采空塌陷及地裂缝的影响范围扩大,就本区而言,较传统理论预测范围扩大了243m,相当于采空地面变形影响角减小为48°．     

某洞库裂缝原因分析及加固设计

在分析某洞库裂缝原因的基础上,采用间隔增设二次衬砌的方法对洞库进行了加固设计,提出了以控制原衬砌混凝土不出现裂缝的原则来确定二次衬砌间距的确定方法,并利用叠合构件位移协调的条件推导出了二次衬砌上荷载的计算公式,为洞库的二次衬砌加固提供了一套设计方法。     

老挝Nam Ngum 5水电站重力拱坝裂缝处理实践

针对老挝Nam Ngum 5水电站重力拱坝裂缝进行的灌浆处理,采用化学灌浆和水泥灌浆相结合,取得了良好的治理效果。详细介绍了裂缝深度的检测方法和裂缝止裂措施,以及灌浆施工工艺。     

利用目标点最小生成树的路面裂缝检测

分析路面裂缝的成像特点,提出了一种基于目标点最小生成树的路面裂缝检测方法。最小生成树具有描述空间线性聚集特征的优点,有利于实现对裂缝的全局分析和提取。实验结果表明,对不连续裂缝的处理,本文方法优于传统方法。     

弹性各向异性介质岩石体波相速度计算

综述弹性波相速度计算的若干严格数值方法和近似解析方法,对数值算例及对不同方法作了比较.结果显示,不同数值方法得到结果一致,其适用于计算任意复杂各向异性介质岩石的相速度,但不便从物理意义的角度去分析物理参数对速度的影响;而近似解析解虽然精确程度各有不同,但是便于从物理意义的角度去进行速度分析,并在此基础上解析求取群速度这...     

Microbial mats implicated in the generation of intrastratal shrinkage (‘synaeresis’) cracks

Intrastratal shrinkage (often termed ‘synaeresis’) cracks are commonly employed as diagnostic environmental indicators for ancient salinity‐stressed, transitional fluvial‐marine or marginal‐marine depositional environments. Despite their abundance and use in facies interpretations, the mechanism of synaeresis crack formation remains controversial, and widely accepted explanations for their formation have hitherto been lacking. Sedimentological, ichnological, petrographic and geochemical study of shallow marine mudstone beds from the Ordovician Beach Formation of Bell Island, Newfoundland, has revealed that crack development (cf. synaeresis cracks) on the upper surface of mudstone beds is correlated with specific organic, geochemical and sedimentological parameters. Contorted, sinuous, sand‐filled cracks are common at contacts between unbioturbated mudstone and overlying sandstone beds. Cracks are absent in highly bioturbated mudstone, and are considered to pre‐date firmground assemblages of trace fossils that include Planolites and Trichophycus. The tops of cracked mudstone beds contain up to 2·1 wt% total organic carbon, relative to underlying mudstone beds that contain around 0·5 wt% total organic carbon. High‐resolution carbon isotope analyses reveal low δ¹³C_org values (?27·6‰) on bed tops compared with sandy intervals lacking cracks (?24·4 to ?24·9‰). Cracked mudstone facies show evidence for microbial matgrounds, including microbially induced sedimentary structures on bedding planes and carbonaceous laminae and tubular carbonaceous microfossils in thin section. Non‐cracked mudstone lacks evidence for development of microbial mats. Microbial mat development is proposed as an important prerequisite for intrastratal shrinkage crack formation. Both microbial mats and intrastratal shrinkage cracks have broad palaeoenvironmental distributions in the Precambrian and early Phanerozoic. In later Phanerozoic strata, matgrounds are restricted to depositional environments that are inhospitable to burrowing and surface‐grazing macrofauna. Unless evidence of synaeresis (i.e. contraction of clay mineral lattices in response to salinity change) can be independently demonstrated, the general term ‘intrastratal shrinkage crack’ is proposed to describe sinuous and tapering cracks in mudstone beds.     

莱芜市用地瓶颈措施问题解析

当前,国家收紧地根,从严控制新增建设用地指标成为各地建设项目顺利落地的制约瓶颈。为破解这一难题,结合莱芜实际,分析了规划修编、指标利用、挖潜存量、加快供地等做法,对保障项目用地提出了建议和对策。