新建高铁隧道小净距下穿公路隧道结构安全影响分析

为了分析新建隧道建设对所交叉的既有隧道结构的安全影响,以西渝高铁徐家坡隧道为例,采用地层结构法,建模分析计算了新建隧道开挖不同进尺阶段既有隧道的变形情况。结果表明,新建隧道下穿既有隧道开挖至既有隧道正下方时交叉位置发生塑性区贯通,影响较大,该施工时间节点应重点加强超前支护防护;下穿隧道开挖引起上方既有隧道竖向位移最大,且竖向位移随着下方新建隧道的开挖进尺不断增大;既有公路隧道竖向最大位移较大,安全风险较大,应采取相应的超前预加固措施。

深海天然气水合物机械-热联合开采方法研究综述

天然气水合物由于储量大、污染低等优点,已成为我国非常重要的战略能源,世界各国也加快了天然气水合物的勘探和开发工作.经济高效的开采方法以及相关的灾害控制和环境保护是对天然气水合物进行商业化开采必须要解决好的两个关键问题.目前,注热法和降压法的联合使用被认为是最为有效的天然气水合物开采方法.在降压法和注热法中,天然气水合物开采涉及传热、相变、渗流和变形等物理过程和效应,而传热最慢且相变会消耗大量的热量,无法直接采用常规的单纯依靠渗流原理的油气开采方案来开采天然气水合物.我国南海的天然气水合物主要赋存于粉砂质黏土和粉细砂等类型的沉积物中,胶结性差且埋深较浅.常规的开采方法还不适合我国南海的水合物开采,需要考虑新型的开采方式,这其中提高沉积层中的热传导效率是天然气水合物开采的关键.郑哲敏提出了机械-热联合开采的新概念方法,利用无穷无尽表层海水的热量,基于对流传热的原理和管道输送技术,并兼顾类似采煤挖掘可能导致的深海浅软地层安全问题.天然气水合物机械-热联合开采法是一种新的概念模式,具有开采可控、高效且能有效降低地层安全性风险的优点.本文针对该新方法的能量、装备、经济可行性进行综合评估,阐述了针对核心问题管道含相变气液固多相流动、地层安全方面的研究进展,展望了未来推广应用的空间.

废弃油基钻井液处理技术概况及其应用

文章阐述了热蒸馏、溶剂萃取、超临界流体抽提、坑内密封掩埋、注入安全地层或环行空间、生物修复、化学破乳几种废弃油基钻井液处理技术及其应用实例,分析各处理技术的优缺点。每一种处理技术都存在不足,必须结合油田实际生产,选择适宜有效的处理技术。生物修复法是当前最具前景也是最具难度的处理技术。

Study on Critical,Modern Technology for Mining in Gassy Deep Mines

To achieve safe and highly efficient mining in the gassy, deep mines of the Huainan collieries simultaneous coal and gas extraction, and the corresponding ventilation methods were developed. This includes a set of mining procedures and principles which help insure safe and efficient production. Furthermore, green mining, meaning the comprehensive use of emitted gas, proper treatment of the environment and appropriate mine temperature control, is now standard. The concepts of modem mining and the principles of pressure relief are described. Coal-gas simultaneous ex- traction and multi-pressure relief techniques were developed which require a combination of surface and underground gas extraction. The application of Y-ventilation systems, of roadways retained along goafs, of stress control techniques for highly fragile mine roofs and of powerful, automatic and reliable mining equipment contributes to safe operation of modem deep mines. Operating parameters for these techniques are described and the results of their use discussed.

Numerical simulation of dewatering thick unconsolidated aquifers for safety of underground coal mining

With an increase of mining the upper limits under unconsolidated aquifers, dewatering of the bottom aquifer of the Quaternary system has become a major method to avoid water and sand inrushes.In the 8th District of the Taiping Coal Mine in south-western Shandong province, the bottom aquifer of the Quaternary system is moderate to excellent in water-yielding capacity.The base rock above the coal seam is very thin in the concealed coal field of the Carboniferous and Permian systems.Therefore, a comprehensive dewatering plan from both the ground surface and the panel was proposed to lower the groundwater level in order to ensure mining safety.According to the hydrogeologic conditions of the 8th District, we established a numerical model so that we could simulate the groundwater flow in the dewatering process.We obtained the simulation parameters from previous data using backward modeling, such as the average coefficient of permeability of 12 m/d and the elastic storage coefficient of 0.002.From the same model, we predicted the movement of groundwater and water level variables and obtained the visible effect of the dewatering project.Despite the overburden failure during mining, no water and/or sand inrush occurred because the groundwater level in the bottom aquifer was lowered to a safe water level.

精细控压压力平衡法固井技术的应用实践

精细控压钻井技术多用于解决同一裸眼油气井段存在多压力系统、窄安全密度窗口地层的安全钻进难题,其尾管固井作业若采用常规方法,在满足小间隙尾管固井顶替效率的前提下,施工过程中必然造成井漏;若采用"正注反打"工艺,固井质量又难以满足后期超深井试油工程的需要。为此,以四川盆地剑阁构造上所钻龙岗70井?114.3 mm尾管固井作业为例,探索精细控压压力平衡法固井技术在多储层、高低压互存、长裸眼段(859 m)中的固井应用。具体做法如下:①采取了确保水泥浆环空充填效率、固井施工全过程压力平衡等针对性的技术措施;②依靠精细控压钻井装置和中心管泵注加重钻井液的方式,精确控制环空压力平衡来降低钻井液密度,实现窄安全密度窗口地层的固井施工全过程井筒压力平稳。现场试验结果表明,该井?114.3 mm尾管固井质量良好,分阶段降密度期间喇叭口无窜流,试压合格。结论认为,该方法能够提高复杂超深气井尾管的固井质量,改善了后期高压气井试油安全作业的井筒条件。

Running safety and seismic optimization of a fault-crossing simply-supported girder bridge for high-speed railways based on a train-track-bridge coupling system

Bridges crossing active faults are more likely to suffer serious damage or even collapse due to the wreck capabilities of near-fault pulses and surface ruptures under earthquakes.Taking a high-speed railway simply-supported girder bridge with eight spans crossing an active strike-slip fault as the research object,a refined coupling dynamic model of the high-speed train-CRTS III slab ballastless track-bridge system was established based on ABAQUS.The rationality of the established model was thoroughly discussed.The horizontal ground motions in a fault rupture zone were simulated and transient dynamic analyses of the high-speed train-track-bridge coupling system under 3-dimensional seismic excitations were subsequently performed.The safe running speed limits of a high-speed train under different earthquake levels(frequent occurrence,design and rare occurrence)were assessed based on wheel-rail dynamic(lateral wheel-rail force,derailment coefficient and wheel-load reduction rate)and rail deformation(rail dislocation,parallel turning angle and turning angle)indicators.Parameter optimization was then investigated in terms of the rail fastener stiffness and isolation layer friction coefficient.Results of the wheel-rail dynamic indicators demonstrate the safe running speed limits for the high-speed train to be approximately 200 km/h and 80 km/h under frequent and design earthquakes,while the train is unable to run safely under rare earthquakes.In addition,the rail deformations under frequent,design and rare earthquakes meet the safe running requirements of the high-speed train for the speeds of 250,100 and 50 km/h,respectively.The speed limits determined for the wheel-rail dynamic indicators are lower due to the complex coupling effect of the train-track-bridge system under track irregularity.The running safety of the train was improved by increasing the fastener stiffness and isolation layer friction coefficient.At the rail fastener lateral stiffness of 60 kN/mm and isolation layer friction coefficients of 0.9 and 0.8,respectively,the safe running speed limits of the high-speed train increased to 250 km/h and 100 km/h under frequent and design earthquakes,respectively.

Study on the law of methane seepage in the wall of drainage roadway in mining seam-group

Based on the equation of the gas flow continuity and state, Darcy law and Langmuir equation, the law of methane seepage in the wall of drainage roadway was studied. The governing equation of methane one-way seepage in the seam was founded. By solving the equation, the calculation of methane seepage velocity in the coal wall was worked out. The result has really applied worth and will give beneficial references to re-lated research, it provides preventing coal and gas outbursts with theoretical gist.

Evaluating the Ecological Security of Land Resources based on Multi-source Data in the Altay Region of China

As a material carrier contributing to human survival and social sustainable development,the ecological environment is declining in its integrity and overall health.With the rapid development of society and economy,it is currently very necessary to carry out ecological security evaluation research to provide scientific guidance and suggestions for the construction of ecological civilization and the harmonious co-existence between man and nature.Taking Altay region as the research area,this paper collected and integrated regional geological,geographical,cultural,socio-economic,and statistical data,as well as previous research results.Combined with DPSIR and EES framework model,the evaluation index system of land resource ecological security in Altay region was constructed by using the analytic hierarchy process,entropy method and linear weighted summation function method.Using this index system,the evaluation research work was carried out to determine the current state of the security situation and the major threats which should be addressed.(1)The overall ecological security situation of Altay region was relatively safe,while the local ecological security situation was relatively fragile.Among them,the areas with safe and safer ecological environment accounted for 38.72%,while the areas with critically safe status accounted for 30.83%,and the areas with a less safe and unsafe environment accounted for 30.45%.In terms of spatial characteristics,the areas with unsafe ecological environment were mainly distributed in the west and east of the study area,while the areas with good ecological environment were distributed in the north of the study area.(2)Large-scale mining activities,frequent geological disasters,large-scale reclamation and long-term cultivation of arable land,and long-term large-scale grazing activities resulting in the destruction of grassland and vegetation were the main factors leading to the prominent ecological security problems of land resources in the Altay region.Therefore,in the process of the continuous development of the urban economy,we should pay more attention to the harmony between man and nature,and also actively and effectively advocate and implement certain policies and measures,such as returning farmland to forest,returning grazing land to grassland and integrating the mining of mineral resources.

精细控压压力平衡法固井技术的应用实践

在油田开发中,为解决多压力系统和窄安全密度的窗口裸眼井段的地层钻进难题,多采用精细控压法的钻井工艺技术。在进行尾管固井施工作业中,如果以常规方法为主,能够使小间隙的尾管固井的顶替效率得以满足,但是作业中一定会造成井漏;如果以"正注反打"技术工艺为主,固井质量就难以保证,不能满足后期开发超深井的基本试油工程的条件需要。为此,在现有技术设备条件下,尝试利用精细控压技术实施尾管固井施工作业,能够取得良好的效果,通过近几年的推广,该项工艺技术,在油田开发中,发挥了较强的技术优势,提高了超深油气井复杂井段的尾管固井质量,对稳定生产,提高效率起到了积极的作用。本文通过对盆地油田、平原油田、沙漠油田、海上油田等多家油井运用精细控压和压力平衡技术在深井固井作业中的应用资料,对该项技术在实际应用中的优化改进,提出了具体的看法和建议。