Novel shape indices for vector landscape pattern analysis     

Ce Zhang  Peter M. Atkinson 《International journal of geographical information science》2016,30(12):2442-2461

The formation of an anisotropic landscape is influenced by natural and/or human processes, which can then be inferred on the basis of geometric indices. In this study, two minimal bounding rectangles in consideration of the principles of mechanics (i.e. minimal width bounding (MWB) box and moment bounding (MB) box) were introduced. Based on these boxes, four novel shape indices, namely MBLW (the length-to-width ratio of MB box), PAMBA (area ratio between patch and MB box), PPMBP (perimeter ratio between patch and MB box) and ODI (orientation difference index between MB and MWB boxes), were introduced to capture multiple aspects of landscape features including patch elongation, patch compactness, patch roughness and patch symmetry. Landscape pattern was, thus, quantified by considering both patch directionality and patch shape simultaneously, which is especially suitable for anisotropic landscape analysis. The effectiveness of the new indices were tested with real landscape data consisting of three kinds of saline soil patches (i.e. the elongated shaped slightly saline soil class, the circular or half-moon shaped moderately saline soil, and the large and complex severely saline soil patches). The resulting classification was found to be more accurate and robust than that based on traditional shape complexity indices.  相似文献   

Rotation Center and Horizontal Bearing Capacity of the Bucket Foundation in Soft Ground     

Xiaowei Tang  Xiwen Zhang  Qi Shao  Zhenqing Li 《Marine Georesources & Geotechnology》2016,34(6):594-601

In the last 20 years, the bucket foundation has been developed as a new type of offshore platform structure. Because of its short period of application to engineering practices, the theoretical decision on the rotation center and horizontal bearing capacity of the bucket foundation has yet to be agreed. A limit analysis method is used to determine the updated rotation center position and horizontal bearing capacity to evaluate the failure mechanisms of the bucket foundations. The results are compared with numerical simulation and experiments, and also with other theoretical methods. The proposed method can satisfactorily consider the engineering conditions and the result is accurate in determining the rotation center and horizontal bearing capacity.  相似文献   

Numerical Studies on Piled Gravity Base Foundation for Offshore Wind Turbine     

Yun Wook Choo  Ji-hoon Seo  Young-Nam Kim  Jeong-min Goo  Young-ho Kim 《Marine Georesources & Geotechnology》2016,34(8):729-740

This study aims to investigate a hybrid gravity base foundation to support offshore wind tower. A new hybrid gravity base foundation considered in this study has five component piles, referred to as ‘piled gravity base foundation’. The three-dimensional finite element analyses were carried out for the piled gravity base foundation subjected to a combined load with a lateral load and overturning moment. The parametric analyses were undertaken varying the loading height and direction, the rigidity of the piled gravity base foundation, the field soil layers, and the clay strength. Overall, the response of the piled gravity base foundation was significantly influenced by the interaction between the cone base piles and the surrounding soil. The increased strength of the soil led to a significant reduction of the pile and gravity base foundation responses, in terms of the bending moments, axial forces, lateral displacements, and rotations.  相似文献   

坑式钢管静压桩在地基加固中的应用     

周军怀  李向阳  柴卓 《探矿工程》2018,45(11):56-59

坑式钢管静压桩是解决既有建筑物因软弱土层地基产生沉降变形的一种技术方法。针对山西北化关铝化工有限公司质检楼地基沉降变形及工程地质条件,提出了采用坑式钢管静压桩进行加固处理的设计方案,介绍了坑式钢管静压桩施工方案和施工流程及注意事项;总结了施工过程中遇到的问题,并对施工后的监测数据进行了分析。结果表明,坑式钢管静压桩施工对软弱地基加固效果良好,可成功地解决软弱土层产生的地基沉降开裂问题。  相似文献   

软土区旋喷式插筋微型桩工艺试验研究     

吴越琛  王进明  陆舟超 《探矿工程》2018,45(12):74-78

软土地质条件下建筑物的沉降变形和承载力要求越来越高,对基础施工工艺提出了较高要求。在高压旋喷施工工艺的基础上,提出旋喷式插筋微型桩施工工艺,开展了微型桩工艺试验研究,结果表明该工艺大幅提高了单桩桩基承载性能,为实际工程应用提供了技术数据支持。  相似文献   

高速公路通道下沉开裂治理实践     

张锦灵  豆敬峰  李金刚 《探矿工程》2018,45(6):75-80

河南省省道323线登封市大冶镇一段公路软弱地基以及路面出现不均匀沉降,通道箱涵开裂,边坡为欠稳定边坡。将事故路段分为4个区域进行加固治理。通过采用注浆加固路基基础、设置坡面排水系统、提高地基的承载能力等治理措施,保证了道路的通行能力。  相似文献   

粗砂砾石地层中高压旋喷桩隔水帷幕施工技术          下载免费PDF全文

张红涛 《探矿工程》2021,48(6):113-117

太原万达广场A2区商住楼基坑工程部分区域为粗砂砾石地层,基坑隔水帷幕中深层搅拌桩无法有效使用。提出了在粗砂砾石地层采用高压旋喷桩隔水帷幕的施工技术方案,采用双套管锚杆钻机引孔、单管高压喷射工艺进行施工,成功实施了这一工程。经检查,喷射注浆体相互咬合良好,有效桩径内水泥含量均匀无夹块现象,隔水帷幕止水效果良好。  相似文献   

护坡桩+微型钢管桩复合土钉墙联合支护体系研究应用          下载免费PDF全文

孙剑  范民浩  李鑫 《探矿工程》2021,48(10):116-124

本文提出了一种新的联合支护体系——护坡桩+微型钢管桩复合土钉墙支护体系,成功解决了基坑周边无放坡空间需垂直开挖、基坑深度大、要求位移小、支护费用高等技术难题,做到了施工便利,对控制边坡位移变形、增强边坡整体稳定性、保证在基坑开挖工程中不发生对周围环境的影响具有良好的作用。采用这种支护方式对北京一工程进行设计施工探讨,经工后监测效果良好,大大地提高了边坡的安全稳定性,从而验证了这一支护形式的可行性,其在深基坑支护中具有常规土钉墙和护坡桩无法相比的技术与经济优势,可供其他类似工程参考,具有较高的适用推广价值。  相似文献   

岩溶坝基帷幕灌浆高注浆量控制措施与效果分析          下载免费PDF全文

张正雄 《探矿工程》2021,48(7):121-125

帷幕灌浆是坝基防渗处理的一种常用技术手段,而岩溶地区因其岩溶发育致使岩溶裂隙和通道纵横交错,且难以获取其规律性,灌浆过程中往往会出现注浆量偏高的现象。为了能够既有效控制帷幕灌浆成本,又确保帷幕灌浆施工质量,就需要采用科学、合理、可靠的施工技术措施和手段,对高注浆量的情况进行重点控制和改进。本文结合某水电站岩溶坝基帷幕灌浆中突出的高注浆量现象,通过有针对性地从技术措施和控制手段等方面的综合探索与应用,最终达到了坝基防渗的目的,并最大限度地节约了帷幕灌浆的时间,有效控制了高材料消耗所带来的高成本问题,为类似项目的帷幕灌浆积累了一定的经验。  相似文献   

复杂地质条件和敏感环境中基坑设计实践及关键技术          下载免费PDF全文

邵晨晨 《探矿工程》2021,48(6):102-108

上海某国际金融大厦深大基坑项目北侧紧邻运营轨道交通8号线区间隧道,最近处仅7.87 m,南侧与现有世博共同管沟净距2.0~3.0 m,基坑变形控制要求高,周边环境敏感。同时,本项目位于黄浦江畔,场地浅层为典型的淤泥质软土地层,下部为富含承压水粉（砂）土层,且微承压水层与第一、第二承压水层互为连通,止水帷幕无法隔断承压水层,地质条件复杂。设计采用分坑施工、被动区加固、预应力伺服钢支撑系统、抽灌一体化降水方案、超深地下连续墙、跟踪注浆、型钢垫层等技术方案。实测结果表明,区间隧道的最大变形6.52 mm,共同管沟的最大变形15.3 mm,其最大变形均满足变形控制要求,确保了运营区间隧道和共同管沟的安全。  相似文献