Case Study on Synchronous Construction Technology for Secondary Lining of Large-diameter Single track Shiel Shield-bored ored Tunnel

The synchronous construction of the secondary lining during the boring of large-diameter shield faces challenges such as the design of the lining jumbo,the high requirements on the performance for the lining jumbo,the organization of the construction activities in the small and confined area,the horizontal transportation for shield boring and high safety management requirements.A super-long invert lining construction jumbo,as well as the matching California switch,is developed,which provides solution for the confliction between the invert lining construction and the horizontal transportation.The procedure and method for the synchronous operation of the shield boring and the secondary lining are developed by referring to the synchronous construction of the secondary lining during the boring of the TBMs in hard rocks.Due to the adoption of the synchronous operation of the shield boring and the secondary lining,the construction period is shortened and the construction cost is reduced.The paper can provide reference for the synchronous construction of the secondary lining in similar projects in the future.

An Approach to Stability Analysis of Embedded Large-Diameter Cylinder Quay

The large-diameter cylinder structure, which is made of large successive bottomless cylinders placed on foundation bed or partly driven into soil, is a recently developed retaining structure in China. It can be used in port, coastal and offshore works. The method for stability analysis of the large-diameter cylinder structure, especially for stability analysis of the embedded large-diameter cylinder structure, is an important issue. In this paper, an idea is presented that is, embedded large-diameter cylinder quays can be divided into two types, i.e. the gravity wall type and the cylinder pile wall type. A method for stability analysis of the large-diameter cylinder quay of the cylinder pile wall type is developed and a method for stability analysis of the large-diameter cylinder quay of the gravity wall type is also proposed. The effect of significant parameters on the stability of the large-diameter cylinder quay of the cylinder pile wall type is investigated through numerical calculation.

Coupled BEM-FEM Analysis of the Large-Diameter Cylinder Structure System

A method of coupled BEM-FEM analysis for the elastic spatial structure system is presented. It can be applied to the calculation of the stress and deformation of the large-diamater cylinder structure system and it is suitable for symmetric or non-symmetric structures under the distributed or concentrated load. Numerical examples show that the proposed method and computer program BEFEM are quite efficient in the analysis of the large-diameter cylinder structure problems in ocean engineering.

Selection of superior families of Pinus massoniana in southern China for large-diameter construction timber

This study addresses the increasing demand for large-diameter production timber,and considers the time and space variability of half-sib families of Pinus massoniana.Height,diameter at breast height(DBH)and timber volume of 440 open-pollinated half-sib progeny families were investigated in 14 progeny trials in different years and production regions.An evaluation of the genetic variation of all half-sib families was carried out during the sustainable rapid growth period and individual volumes were characterized as a major index.ANOVA analysis showed that there was considerable variance in the growth traits of most families in different years and on different sites.The variations caused by temporal and spatial changes of the mating system required three selection methods for analysis.The results show that there were differences among the heritabilities of different growth traits by different halfsib progenies.Average heritability values of height,DBH and volume were 0.33,0.34 and 0.36,respectively.Fortyfive superior families were selected in every progeny test,12 were selected in progeny trials by different years and five in different habitat progeny trials.Three superior families(Gui GC553A,Gui GC414A and Gui GC431A)were selected,although in different years and production regions.The genetic gains of timber volume of these selected r families ranged from 1.20 to 47.00%,which could provide a foundation for superior wood property selection and serve as material for seed improvement and extension in surrounding areas.

Theoretical Analysis and Experimental Study on Breakaway Torque of Large-diameter Magnetic Liquid Seal at Low Temperature

The existing researches of the magnetic liquid rotation seal have been mainly oriented to the seal at normal temperature and the seal with the smaller shaft diameter less than 100 mm. However, the large-diameter magnetic liquid rotation seal at low temperature has not been reported both in theory and in application up to now. A key factor restricting the application of the large-diameter magnetic liquid rotation seal at low temperature is the high breakaway torque. In this paper, the factors that influence the breakaway torque including the number of seal stages, the injected quantity of magnetic liquid and the standing time at normal temperature are studied. Two kinds of magnetic liquid with variable content of large particles are prepared first, and a seal feedthrough with 140 mm shaft diameter is used in the experiments. All experiments are carried out in a low temperature chamber with a temperature range from 200℃ to -100℃. Different numbers of seal stages are tested under the same condition to study the relation between the breakaway torque and the number of seal stages. Variable quantity of magnetic liquid is injected in the seal gap to get the relation curve of the breakaway torque and the injecting quantity of magnetic liquid. In the experiment for studying the relation between the breakaway torque and the standing time at the normal temperature, the seal feedtrough is laid at normal temperature for different period of time before it is put in the low temperature chamber. The experimental results show that the breakaway torque is proportional to the number of seal stages, the injected quantity of magnetic liquid and the standing time at the normal temperature. Meanwhile, the experimental results are analyzed and the torque formula of magnetic liquid rotation seal at low temperature is deduced from the Navier-Stokes equation on the base of the model of magnetic liquid rotation seal. The presented research can make wider application of the magnetic liquid seal in general. And the large-diameter magnetic liquid rotation seal at low temperature designed by using present research results are to be used in some special fields, such as the military field, etc.

Longhole waterjet rotary cutting for in-seam cross panel methane drainage

In order to improve the efficiency of gas drainage before and during longwall extraction,a waterjet rotary cutting system has been developed for in-seam cross panel methane drainage.The purpose of the water rotary cutting system developed was to create artificial fractures along the gas drainage boreholes.During the design of the system,it was perceived that the nozzle geometry is one of the key factors,affecting cutting capacity.Therefore,we studied the structural and geometric parameters of the nozzle and optimized its performance during laboratory tests and numerical simulation.Underground trials conducted in a coal mine,indicate that production of gas drainage before and after cutting significantly increased by up to three times.The advantages of waterjet assisted gas drainage method has been identified as:1) increasing gas drainage efficiency,2) a possible development of a gas drainage fractured network within coal seams associated with panel extraction,and 3) reducing the risk of exceeding gas limits during longwalling.

Control study of short-term curative effect of minimally invasive total hip arthroplasty using metal-on-metal large-diameter femoral head for the elderly patients with femoral neck fractures

Objective To discuss the postoperative curative effects of two surgical techniques of minimally invasive total hip arthroplasty (THA) using metal-on-metal largediameter and conventional diameter femoral head for the elderly patients

Drivability of Large Diameter Steel Cylinders During Hammer-Group Vibratory Installation for the Hong Kong–Zhuhai–Macao Bridge

The Hong Kong–Zhuhai–Macao Bridge(HZMB)involved the installation of 120 mega-cylinders with a diameter of 22 m,weights up to 513 t,and penetration depths up to 33 m using an eight-vibratory hammer group.Due to the lack of engineering experience on the drivability of large-diameter cylinders under multiple vibratory hammers,predicting the penetration rate and time of steel cylinders is an open challenge that has a considerable impact on the construction control of the HZMB.In this study,the vibratory penetration of large-diameter steel cylinders in the HZMB is investigated based on geological surveys,field monitoring,and drivability analysis.The vibratory penetration rate,installation accuracy,and dynamic responses of the steel cylinders at both the eastern and western artificial islands are analyzed.The dynamic soil resistance has a great influence on the cylinder drivability.However,the current design methods for estimating the vibratory driving soil resistance are proven inaccurate without considering the scale effects.Therefore,a modified method with a normalized effective area ratio A_(r,eff)is proposed in this study to calculate the vibratory soil resistance for open-ended thin-wall cylinders under unplugged conditions.Considering the scale effects on the vibratory driving soil resistance,the proposed method leads to closer results to the measured data,providing a reference for future engineering practice.

黄土地基中超长钻孔灌注桩承载性状试验研究

为了研究黄土地基中超长钻孔灌注桩的承载性能、桩身轴力传递规律、桩侧阻力和端阻力的发挥性状,对西安地区6根超长钻孔灌注桩进行单桩静载荷试验,采用滑动测微计测试每米范围内桩身轴力的变化。可以发现,黄土地基中超长钻孔灌注桩的Q—S曲线呈缓变型,在最大荷载时都未达到破坏状态;桩身轴力传递规律和桩侧阻力的发挥与成孔工艺、桩长、桩周土层性质密切相关。由于黄土地基中的粉质黏土和粉土具有强结构性,测试得到的极限侧阻力远比规范值要大,使得黄土地基中超长钻孔灌注桩具有较大的承载能力,但桩端阻力和桩侧阻力并非同时发挥,建议在设计时考虑端阻力的发挥度,桩侧摩阻力和桩端阻力采用不同的分项系数。

黄土地区超长钻孔灌注桩荷载传递性状试验研究

通过西安黄土地基中超长钻孔灌注桩静载荷试验和桩身轴力的测试,探讨了黄土地基中超长钻孔灌注桩的承载力 性状和荷载传递规律。超长桩桩身轴力的传递规律和侧摩阻力的发挥性状对黄土地基中超长桩的理论研究和工程应用具有 重要的参考价值。

三维激光扫描技术在大直径深孔采矿中的应用

针对大直径深孔采矿中采场出现的超爆、欠爆情况难以确定的问题。选择某矿山23#、25#采场作为试验场地,使用北京矿冶研究总院自主研发的矿用三维激光扫描仪对23#、25#采场进行现场扫描并进行后续数据分析。数据处理结果表明,矿用三维激光扫描仪非常适合采场爆破效果分析,可以定量给出采场超爆、欠爆尺寸,同时可以为后续二步骤回采爆破设计优化提供数据基础。

地下采矿大直径深孔爆破研究

大直径深孔采矿法因为其高效率、低成本、安全性好在矿山得到了广泛的应用。介绍了我国地下采矿大直径深孔爆破技术的应用研究现状,剖析了主要问题及其危害。而后以铜绿山铜铁矿大直径深孔采矿方案为例,从凿岩工艺、装药结构与爆破参数三个方面,简述了其解决方案与主要优点。

某铁矿采场大直径深孔爆破对含水层稳定性的影响

某铁矿采用大直径深孔阶段空场嗣后充填法进行采矿,为防止深孔大爆破对上覆含水层贯通的导水裂隙产生较大的破坏,建立微震监测系统,对含水层的稳定性进行监测。监测结果表明,目前采场大直径深孔爆破对上覆含水层隔离底板的扰动较小,但是当后续采场大爆破靠近导水裂隙发育带时,大爆破对含水层导水裂隙的影响将会日趋明显,需要进行持续的监测与分析,为后续的爆破优化设计提供依据。

地下残矿高效回采技术研究

根据地下残矿开采形态复杂、安全条件差的特点,对比各种采矿方法优缺点,研究提出利用采空区为补偿空间的区域整体爆破嗣后充填采矿方法。将残矿周围采空区作为爆破补偿空间,利用大直径深孔一次爆破落矿,集中出矿后对采空区进行大流量充填。该技术在残矿开采中取得了良好的应用效果。

Excel VBA在大直径深孔爆破设计的应用

针对地下大直径深孔间隔装药微差爆破设计过程复杂、繁琐、低效、易出错的特点,应用Excel强大的计算统计功能和VBA自动化功能,通过调用函数、编写宏代码及设置控件,构建功能模块,开发了具有参数化数据输入、动态计算与统计、自动生成材料报表、爆破设计优化、自动查错功能的爆破设计表格系统;在凡口铅锌矿大直径深孔采矿实践应用中,表格系统能够快速准确实现爆破设计图的表格化,用于指导爆破现场的精细化施工,并且自动分类统计出爆破器材、单响药量等,取代手工计算,明显提高了设计效率和准确度、降低了工作强度,取得了良好的效果,可为其它间隔装药微差爆破设计提供借鉴。

复杂岩体内的深孔爆破成井

在复杂岩体内用深孔爆破成井法掘进井筒 ,既可解决施工安全问题 ,又能加快施工进度 ,缩短工期。

大直径深孔爆破参数优化研究

针对地下大直径深孔爆破存在的块度不均、超采超爆、边帮控制不佳等问题,在影响爆破效果的主要因素进行理论分析的基础上,采用ANSYS/LS-DYNA软件对大直径深部爆破孔网参数和边界孔装药结构进行模拟研究,确定了不同孔径下最佳的孔网参数和边界孔装药结构。将爆破参数优化结果应用于凡口铅锌矿井下大直径深孔爆破现场,取得了良好的爆破效果,研究结果为类似矿山大直径深孔爆破参数优化提供理论依据和和技术参考。

安庆铜矿不规则二步骤矿柱采场回采实践

本文针对安庆铜矿两侧矿房回采后矿体形态极不规整的"二步骤"矿柱采场,提出了小孔径VCR法掏槽及扇形中深孔侧向崩矿的回采方案,克服了传统钻凿切割天井掏槽采切比高、劳动强度大、安全性差等缺点,为矿山持续高产、稳产提供了技术保证。不仅取得了显著的经济效益,而且对类似矿山相似采场的回采有良好的参考作用。

黄土地区两种成孔工艺钻孔灌注长桩承载力性状对比研究

旋挖钻孔灌注桩和泥浆护壁钻孔灌注桩是近年来黄土地基中广泛使用的桩基形式。本文通过黄土地基中旋挖钻孔灌注长桩和泥浆护壁钻孔灌注长桩静载荷试验和桩身应力的测试,分析了黄土地基中两种成孔工艺钻孔灌注长桩桩身轴力的传递规律、桩侧阻力及桩端阻力的发挥性状,探讨了两种成孔工艺对钻孔灌注长桩承载力的影响。

高阶段大直径深孔嗣后充填采矿法在某铁矿的应用研究

针对某急倾斜厚大铁矿体的开采现状,开展采矿方法研究。在查阅国内外类似矿体开采现状的基础上,提出了几种可行的采矿方法。综合分析各采矿方法的安全、高效、经济等主要指标,认为采用高阶段大直径深孔嗣后充填采矿技术能够满足矿山大规模开采要求,可以实现急倾斜厚大矿体的低成本高效开采。同时对国内外其他类似矿体开采起到借鉴意义。