提高连续墙抓斗入岩效率若干问题的探讨          下载免费PDF全文

贾学强  苏伟  丁洪亮  刘永光 《探矿工程》2015,42(10):59-62

越来越多的连续墙工程提出了入岩要求,而现阶段广泛使用的连续墙抓斗入岩效率低下,针对这种状况,以抓斗抓取地层的特点为出发点,对其现阶段在岩石地层抓取效率低下的原因进行分析,然后以岩石破碎学为理论支撑,从抓斗自重、油缸闭合力、斗齿布置规格以及抓取方式等方面着手,提出了若干可用于提高抓斗入岩效率的改进建议。  相似文献   

应力分散型预应力抗拔桩系列技术研究与应用          下载免费PDF全文

何世鸣 《探矿工程》2015,42(2):74-78

根据目前国内外预应力抗拔抗浮桩、部分粘结预应力抗拔抗浮桩的优缺点以及使用的局限性——长螺旋钻机对于桩径＞800 mm或桩长＞30 m的桩力不从心,研究了应力分散型预应力抗拔桩及钢筋钢绞线笼系列技术,用于一个直径1 m、桩长60 m的抗拔桩工程,采用旋挖成孔,可实现在工程桩上进行大吨位试桩,受力合理,节省资金和工期,实践证明该系列技术有很好的应用前景。  相似文献   

赤泥库大坝渗漏分析及灌浆处理技术          下载免费PDF全文

黄全海  赵尊亭  王利芳 《探矿工程》2015,42(11):66-69，79

由于施工质量问题,洛阳一个赤泥库大坝在试运行中发生大面积渗漏及管涌。在对渗漏原因进行分析的基础上实施的在坝内坡增设土工膜、坝轴线上游增设帷幕灌浆防渗墙、坝体下游坡面增设排渗沟和排水棱体等抢险加固措施,有效地解决了坝体渗漏问题。在灌浆处理过程中,针对筑坝材料的复杂性和不均匀性,通过施工前的灌浆试验,取得了适合本场地条件的钻孔施工工艺参数及灌浆方式、灌浆压力、灌浆段确定、水灰比比级等施工技术参数,确保了灌浆处理的效果。  相似文献   

武汉钰龙金融广场超深基坑工程设计方案选型          下载免费PDF全文

杜魁  余小国  岳丽娜  李超 《探矿工程》2015,42(12):28-33

以武汉钰龙金融广场超深基坑工程为实例,在结合常用的深基坑设计方案的基础上分别从基坑总体设计方案选定、基坑围护体系选定和设计、支撑体系选定、基坑降水选定、土方开挖方案选型和换撑方案的选定等方面进行探讨,并确定最终的基坑工程设计方案选型,即地下连续墙围护+3道内支撑+管井降水处理承压水的支护方案。  相似文献   

泥沙起动概率的高速摄影测量方法          下载免费PDF全文

苗蔚  陈启刚  李丹勋  钟强 《水科学进展》2015,26(5):698-706

为了通过实验测量泥沙起动概率,基于封闭槽道内开展的泥沙起动实验,系统论述了基于高速摄影的起动概率测量方法所涉及的起动概率定义、相机采样频率、图像处理方法、起动比例与运动比例的关系等关键问题.根据泥沙在水流紊动猝发作用下起动的物理机制,定义实测起动概率为单个紊动猝发周期内,从一定面积床面上冲刷外移的泥沙比例.根据推移质运动概念模型,提出高速图片拍摄间隔应小于推移质运动的中间时间尺度,以捕获泥沙的每一次起动.在高速图像处理时,通过连续两帧图片之间的灰度差实现运动比例的无偏差提取.进一步分析表明,运动泥沙可处于起动、止动或滑翔状态,运动比例等于起动比例、止动比例和滑翔比例之和,起动比例与运动比例之比等于两张图片之间的时间间隔除以推移质运动的中间时间尺度.基于上述关键技术,将高速摄影测量方法用于泥沙起动概率的测量,结果表明,临界起动水流条件时,床沙处于少量起动现象,对应的临界起动概率与窦国仁所推导的2.28%接近.  相似文献   

王家官庄旧村改造基坑支护设计与施工实践          下载免费PDF全文

李先经  王会军  刘心起 《探矿工程》2020,47(1):69-74

介绍了青岛市即墨区王家官庄旧村改造项目基坑支护设计方案与基坑支护实施情况，该工程地层条件复杂，地下水丰富，又靠近石鹏水库，环境条件较复杂，通过采用土钉墙与高压旋喷桩止水帷幕，基坑降水等技术措施的顺利实施，基坑支护效果良好，确保了地下车库基坑开挖、基础施工的安全，施工质量满足相关技术要求。  相似文献   

南昌商业中心深基坑工程组合支护技术          下载免费PDF全文

谢秋明  张青平 《探矿工程》2020,47(9):75-80,96

以南昌市一商业中心深基坑支护工程实例为背景，通过分析周边环境、地质条件、开挖深度,在保证安全的前提下，充分利用各种因素降低基坑支护造价。在地下水控制上，合理确定坑外地下水位控制标高，采用截水、降水的组合形式。基坑支护采用组合支护结构，在不同部位分别采用土钉墙、锚拉式排桩的支护形式；支护结构上，下部采用不同结构类型的组合。通过设计方案比较与优化，做到安全适用、经济合理。  相似文献   

Semi-analytical solution for the water wave diffraction by arrays of truncated circular cylinders in front of a vertical wall     

《Applied Ocean Research》2019

The present study investigates the combined wave field that is induced by the continuous interaction of plane waves with an array of truncated circular cylinders in front of a rigid wall. The long-term goal of the study is the investigation of possible increase in the efficiency of cylindrical Wave Energy Converters (WECs) by putting in the vicinity of the array a barrier to propagation, a wall, that could assist the reflection of the incoming waves. The main task is to develop a generic solution method that is free of conceptual simplifications employed, e.g. by the method of images and the assumption of “pure” wave reflection. To cope with the set task, the proposed method relies on the semi-analytical formulation of the velocity potentials, while the solution is sought by combined expressions that involve polar and elliptical harmonics. The wall is represented as an elliptical cylinder with zero semi-minor axis. This assumption has eventually a beneficial effect to the underlying formulation given that it simplifies significantly the expansions of the involved diffraction potentials.  相似文献   

Controls on metamorphic equilibration: the importance of intergranular solubilities mediated by fluid composition          下载免费PDF全文

W. D. Carlson  J. D. Hixon  J. M. Garber  R. J. Bodnar 《Journal of Metamorphic Geology》2015,33(2):123-146

A dramatic demonstration of the role of intergranular solubility in promoting chemical equilibration during metamorphism is found in the unusual zoning of garnet in pelitic schist exposed at Harpswell Neck, Maine, USA. Many garnet crystals have irregular, patchy distributions of Mn, Cr, Fe and Mg in their inclusion‐rich interiors, transitioning to smooth, concentric zoning in their inclusion‐poor outer rims; in contrast, zoning of Ca and Y is comparatively smooth and concentric throughout. We re‐assess the disputed origin of these zoning features by examining garnet growth in the context of the thermal and structural history of the rocks, and by evaluating the record of fluid–rock interaction revealed in outcrop‐scale veining and fluid‐inclusion assemblages. The transition in the character of garnet zoning correlates with the onset of a synkinematic, simple‐shear‐dominated phase of garnet growth and with a shift in the composition of the intergranular fluid from CO₂‐rich to H₂O‐rich. Compositional variations in garnet are therefore best explained by a two‐stage growth history in which intergranular diffusive fluxes reflect differences in the concentration of dissolved species in these two contrasting fluids. Interiors of garnet crystals grew in the presence of a CO₂‐rich fluid, in which limited solubility for Mn and Cr (and perhaps Fe and Mg) produced patchy disequilibrium overprint zoning, while appreciable solubility for Ca and Y permitted their rock‐wide equilibration. Rims grew in the presence of an H₂O‐rich fluid, in which high intergranular concentrations for all elements except Cr enabled diffusion over length scales sufficient for rock‐wide equilibration. This striking example of partial chemical equilibrium during reaction and porphyroblast growth implies that thermal effects may commonly be subsidiary in importance to solubilities in the intergranular medium as determinants of length scales for metamorphic equilibration.  相似文献   

Modeling the 2D behavior of dry‐stone retaining walls by a fully discrete element method          下载免费PDF全文

James J. Oetomo  Eric Vincens  Fabian Dedecker  Jean‐Claude Morel 《国际地质力学数值与分析法杂志》2016,40(7):1099-1120

The dry‐stone retaining walls (DSRW) have been tipped as a promising solution for sustainable development. However, before recently, their behavior is relatively obscure. In this study, discrete element method (DEM) approach was applied to simulate the plane strain failure of these walls. A commercial DEM package (PFC2D™) was used throughout this study. The authors used a fully discrete approach; thus, both the wall and the backfill were modeled as discrete elements. The methodology for obtaining the micromechanical parameters was discussed in detail; this includes the three mechanical sub‐systems of DSRWs: wall, backfill and interface. The models were loaded progressively until failure, and then the results were compared with the full‐scale experimental results where the walls were loaded, respectively, with hydrostatic load and backfill. Despite its complexity and its intensive calculation time, DEM model can then be used to validate a more simplified approach. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献