The potential of the use of dense fluids for initiating hydraulic stimulation

To improve preferentially the permeability of fractures in the deepest parts of a geothermal reservoir, a dense fluid may be injected during the very first phase of a hydraulic stimulation test. To initiate such a permeability-enhancement process in the 5000 m deep reservoir of the European Enhanced Geothermal System (EGS) project at Soultz-sous-Forêts, France, a concentrated NaCl brine was injected. The effects of this injection were estimated using measured hydraulic and microseismic data. Two tasks associated with hydraulic stimulation have been shown to be important for this purpose: (1) determination of the failure pressures of the various fractures intersecting the open-hole section under stimulation, and (2) calculation of the transient hydraulic pressure profile in the borehole.Using the numerical borehole code HEX-B, the transient pressure profiles during stimulation of wells GPK2 (June 2000) and GPK3 (May 2003) were calculated on the basis of measured wellhead data. A comparison of the temporal history of near-borehole microseismic events during the GPK2 test and downhole pressure development in the open-hole sections of this borehole indicated that use of a dense brine helped stimulate the bottom part of this well. The corresponding analysis for the GPK3 test showed that the failure pressure of the fractures in the bottom part of the wellbore was never exceeded when injecting the dense brine. We can, therefore, assume that the brine had no effect on the fractures in GPK3.     

Plastic collapse moment equations of throughwall axially cracked elbows subjected to combined internal pressure and in-plane bending moment

Plastic collapse moment (PCM) equations of throughwall axially cracked (TAC) elbow subjected to in-plane closing/opening bending moment were previously proposed by the present authors. However, in actual situation, an elbow may often be subjected to combined internal pressure and bending moment loading. The present work investigates the effect of internal pressure on the in-plane plastic collapse moment of throughwall axially cracked elbows through 3-D elastic-plastic finite element analysis. Equations of un-pressurized cases are recommended where it is conservative and in other cases new equations are proposed.     

采场安全监测与冒顶预报

本文总结了声发射现场监测预报的试验结果，提出了采场稳定性预测的综合方法，应用灰色理论预测和神经网络方法较好地解决了采场冒顶预报问题。     

生态修复对策在崩塌地质灾害防治中的应用

山区大部分公路是削山填谷而建成的,由于建设初期生态保护意识的缺乏,致使公路沿线出现了很多裸露的高陡岩质边坡,从而导致各种地质灾害特别是崩塌、滑坡、泥石流等灾害非常发育。本文以省道302沿线（河南省林州市马安山村段）的一处崩塌地质灾害隐患点为例,在充分了解了崩塌危岩体的工程地质条件、水文地质条件、节理发育情况以及稳定性的基础上,采用生态保护修复理论,将崩塌地质灾害防治体系融入到生态景观修复规划中,完善治理区内生态系统的自我恢复能力和防护功能,从而达到防灾减灾生态景观恢复的目的。     

复杂环境下砖砌烟囱的爆破拆除

本文介绍了采用定向爆破拆除一座砖砌烟囱的施工设计方法,包括爆破方案选择、爆破切口设计和爆破安全验算等内容,对类似工程有一定的参考意义。     

青龙电站引水隧道涌水塌方段处理技术

根据青龙电站引水隧洞涌水塌方的实际工程,提出了处治坍塌和涌水的综合治理方案,取得了良好的处理效果,并提出针对该类地质条件的合理施工方案,确保了后期工程的顺利进行。     

湿陷性黄土地基加固深度经验公式的探讨

在强夯加固地基的实践中,一些工程单位和学者结合各自工程实践,提出了几种处理深度的公式,但这些公式因考虑的影响因素不够全面,有局限性。故通过对上述公式的分析比较,结合强夯加固效果,工艺参数与土性指标间的关系,提出了强夯法加固湿陷性黄土的新公式。     

江河崩岸的概化模拟试验研究

根据长江中下游崩岸的基本特征,采用典型崩岸河段原体沙,在试验室中建立了概化坡体模型,针对坡体崩塌破坏机理进行模拟试验研究。结果表明,试验坡体的崩塌破坏表现形式、过程及特征与长江坍塌型崩岸基本相似。渗流强度越大,破坏作用越明显。水流冲刷的破坏作用主要是淘蚀坡脚,使坡体坡度趋缓,崩塌破坏范围及程度随之逐步减小,坡体坡脚未受淘蚀的极限稳定坡度为1∶2至1∶3。     

12层框架角柱与边柱连续倒塌破坏效应分析

参考美国国防部编制的《结构抗连续倒塌设计》(DOD 2009),以12层钢筋混凝土框架为研究对象,基于有限元软件SAP2000,采用拆除构件方法,对角柱和边柱进行连续倒塌破坏效应分析。利用非线性动力分析,研究其抗连续倒塌能力,对结构移柱前后关键构件内力以及塑性铰分布加以对比,进行角柱与边柱连续倒塌的破坏效应分析。     

玉北地区钻井液技术

针对玉北地区古近系膏岩层易蠕变缩径、二叠系火成岩地层易垮塌掉块、奥陶系灰岩地层易漏,导致的钻井周期长、机械钻速低、复杂情况多等问题,优选了适合各开次的钻井液体系。一开选用膨润土聚合物体系,利用其高膨润土含量解决地表流沙层的井壁稳定与井眼清洁问题;二开选用KCl聚磺钻井液,通过强化钻井液的抑制封堵能力与抗污染能力解决了因泥岩段水化膨胀、砂岩段形成虚泥饼造成的阻卡问题,实现了井壁稳定;三开选用KCl聚磺防塌钻井液,解决了高密度钻井液的抗污染问题,实现了深部地层的快速钻进;四开选用低固相聚磺钻井液,大幅度提高了深部地层的钻进速度。