Influence of the Earth Stress on the Development of Gas Reservoirs

Gas reservoirs are located kilometers deep beneath the earth's surface under great earth stresses, including the overburden stress and the horizontal stress. After a well is drilled, the stress condition around the well bore will be changed. During the development, a pressure funnel forms around the hole, with the rock stress redistributed. In this paper, the influence of the earth stress on the gas reservoir development, including the output, the period of the steady output, the recovery and ratio, is researched thoroughly with the theory of reservoir seepage dynamics and clarified with the calculation method. The research shows that the earth stress produces impacts on the development of a gas reservoir when the stress is great.

Accumulation of Rare Earth Elements in Spinach and Soil under Condition of Using REE and Acid Rain Stress

The content and distribution characteristics of REE in spinach and soil under using REE and acid rain stress were studied by pot experiments. The results show that the content of REE is 0 527～0 696 (μg·g -1 ) in the above ground portion of spinach, 2 668～3 003 (μg·g -1 ) in the under ground portion of spinach and 229 09～250 30 (μg·g -1 ) in the soil. With the acidity of acid rain increasing, the leaching of REE in plants and soil is strengthened and the amount of REE reduces with decreasing of pH value. After REE are used, though plants show the selective absorption to Ce group elements (especially spraying on leaves), regardless under acid rain stress or using REE or not, the distribution model of REE in the above ground and under ground portion of plants is basically the same with the control. Plants also follow the Oddo Harkins rule of the REE of distribution abundance, light rare earth elements is enriched, the minus of Eu is abnormal and admeasure of Ce is a rich model. The results show that REE in plants mainly come from soil and are affected by it.

Influence of the earth rotation on the interfacial wave solutions and wave-induced tangential stress in a two-layer fluid system

Interfacial waves and wave-induced tangential stress are studied for geostrophic small amplitude waves of two-layer fluid with a top free surface and a fiat bottom. The solutions were deduced from the general form of linear fluid dynamic equations of two-layer fluid under the f-plane approximation, and wave-induced tangential stress were estimated based on the solutions obtained. As expected, the solutions derived from the present work include as special cases those obtained by Sun et al. （2004. Science in China, Ser. D, 47（12）： 1147-1154） for geostrophic small amplitude surface wave solutions and wave-induced tangential stress if the density of the upper layer is much smaller than that of the lower layer. The results show that the interface and the surface will oscillate synchronously, and the influence of the earth＇s rotation both on the surface wave solutions and the interfacial wave solutions should be considered.

Process Analysis of In-situ Strain during the M_s8.0 Wenchuan Earthquake—Data from the Stress Monitoring Station at Shandan

There were huge life and property losses during the Ms8.0 Wenchuan earthquake on May 12, 2008. Strain fluctuation curves were completely recorded at stress observatory stations in the Qinghai-Tibet plateau and its surroundings in the process of the earthquake. This paper introduces the geological background of the Wenchuan earthquake and the profile of in-situ stress monitoring stations. In particular, data of 174 earthquakes （Ms4.0-Ms8.5） were processed and analyzed with various methods, which were recorded at the Shandan station from August 2007 to December 2008. The results were compared with other seismic data, and further analyses were done for the recoded strain seismic waves, co-seismic strain stepovers, pre-earthquake strain valleys, Earth＇s free oscillations before and after the earthquake and their physical implications. During the Wenchuan earthquake, the strainmeter recorded a huge extensional strain of 70 seconds, which shows that the Wenchuan earthquake is a rupture process predominated by thrusting. Significant precursory strain anomalies were detected 48 hours, 30 hours, 8 hours and 37 minutes before the earthquake. The anomalies are very high and their forms are very similar to that of the main shock. Similar anomalies can also be found in strain curves of other shocks greater than Ms7.0, indicating that such anomalies are prevalent before a great earthquake. In this paper, it is shown that medium aftershocks （Ms5.5- 6.0） can also cause Earth＇s free oscillations. Study of free oscillations is of great significance to understand the internal structure of the Earth and focal mechanisms of earthquakes and to recognize slow shocks, thus providing a scientific basis for the prevention and treatment of geological disasters and the prediction of future earthquakes.

Alleviation Effects of Rare Earth on Cd Stress to Rape

Using rapes as test materials, the fastness expression and alleviation effect of rapes were studied under Cd stress condition, as the rapeseeds were dipped in the single element(La, Ce, Nd, Pr)and mixed rare earth(RE). The results indicate that, under Cd stress, the dry and fresh weight are increased by both the single element and mixed rare earth treatment, and the fastness of rape is improved.The single element of rare earth decreases the Cd content in rape roots and transmits Cd to the edible parts above the ground in which the alleviation effect of Ce is most significant.La treatment takes the second place, so that the poisonous effect of heavy metal Cd is eased.The mixed rare earth doesn't alleviate the assimilation of Cd in rape roots, but accelerates the transfer of Cd to the parts above the ground. The research puts forward that the alleviation of rare earth on Cd stress has connection with the decrease of Ca content.

Effects of Rare Earth on Oxidative Damage and Redox System of Wheat Seedling Leaves under Water Stress

After treated with low concentration of La^3 ＋ , the rate of producing active oxygen free radical, the relative permeability of cell membrane, the contents of bivalent iron ion in wheat seedling leaves under water stress were determined. The results show that in wheat seedling leaves, feasible concentrations of La^3 ＋ decreases the accumulation of active oxygen free radical, inhibits the increase of the relative permeability of cell membrane, reduces the content of peroxidation product MDA of membrane lipid, and prevents the plant cell producing more bivalent iron ion which can catalyzed the reaction of Haber-weiss and Fenton to produce more superoxide anion. In addition, purified plasma membrane was isolated by aqueous two-phase partitioning from wheat seedling leaves. The reduction rate of Fe（CN）6^3- by purified plasma membrane in La^3＋ -treated wheat seedling leaves is different from those in the absence of La^3＋ under water stress. The changing trend of the redox activity to La^3＋ is similar to that of the content of Fe^2＋ . The results reveal that extraneous La^3＋ can alleviate the damages of cell membrane caused by water stress via promoting the activity of redox system and the ability of eliminating ROS in wheat seedling leaves.

不同埋深条件下盾构施工扰动试验研究

随着城市地下空间开发规模不断扩大,盾构施工诱发的地层扰动对地下既有建(构)筑物及周边环境的安全产生了重要的影响。通过自主研发盾构掘进试验装置,实现了不同地层应力水平的加载,分析了不同埋深条件下盾构施工地层扰动的变化规律及影响范围。研究结果表明:隧道周围地层中土压力变化率随着距隧道水平距离的增大而逐渐递减;盾构掘进完毕后土压力相对于初始土压力减少了约20%~40%;埋深比变化对拱顶、拱底处的土体应力路径影响较小;定义了基于土压力力变化的地层扰动度,随埋深比的增大,地层扰动度逐渐减小,说明深埋条件会降低盾构开挖对地层的扰动作用;盾构掘进完毕后,扰动作用的竖向影响范围高度介于隧道上下0.5D~0.8D(D为隧道直径)之间,当盾构到达监测断面时水平扰动范围宽度约为0.5D,盾构穿越远离后近似为1.2D~1.5D。

开挖前抽水条件下基坑围挡两侧非极限土压力计算模型

基坑开挖前的坑内抽水可引起围挡发生厘米级的侧移,但现行基坑设计理论仅提出了基于弹性支点法的土方开挖诱发围挡受力变形的计算方法,却并未提出如何计算基坑开挖前抽水引起的围挡侧移。若要沿用弹性支点法进行抽水侧移的计算,则如何确定抽水过程中围挡两侧土压力分布成为关键。为了提出基坑开挖前抽水条件下围挡两侧土压力的计算模型,首先提出了基坑开挖前抽水过程中围挡两侧土体受扰动区形态与范围;然后探明了扰动区内土体应变分布规律并提出土体应变分布模式;进一步地,建立了土体应变与围挡侧移的数学方程,并结合土体应力−应变方程最终构建了开挖前抽水条件下考虑基坑围挡侧移影响的土压力计算模型。所提出的土压力模型能够反映基坑开挖前抽水过程中围挡侧移对土压力的非线性影响,公式形式简单,参数取值方便,可为后续预测抽水引起的基坑围挡侧移提供重要基础。

钢板混凝土组合地下群罐罐壁受力性能分析

为探究钢板-混凝土组合地下群罐罐壁在施工回填过程中的受力性能,本研究对某实际地下群罐工程开展了现场试验,分析群罐罐壁在填土过程中外侧土压力以及环向和竖向钢筋的应力变化规律。结果表明:在土压力作用下,罐壁整体呈受压状态,环向及竖向应力最大值皆位于罐壁中部位置;罐壁竖筋应力均大于环筋应力,且最大应力约是环筋最大应力的1.5~2倍;土压力实测值分别是理论计算得到的被动土压力、静止土压力和主动土压力的0.49倍、2.01倍和6.32倍,为保证地下群罐结构受力的安全性,建议采用被动土压力作为设计用土压力。

Measurement and study of the distributing law of in-situ stresses in rock mass at great depth

To solve the technical cruxes of the conventional system in deep rock mass, an automatic testing system for hydraulic fracturing that includes a single tube for hydraulic loop, a pressure-relief valve, central-tubeless packers, and a multichannel real-time data acquisition system was used for in-situ stresses measurement at great depths （over 1000 m） in a coalfield in Juye of Northern China. The values and orientations of horizontal principal stresses were determined by the new system. The virgin stress field and its distributing law were decided by the linear regression from the logged 37 points in seven boreholes. Besides, the typical boreholes arranged in both the adjacent zone and far away zone of the faults were analyzed, respectively. The results show that a stress concentration phenomenon and a deflection in the orientation of the maximal horizontal stress exist in the adjacent zone of the faults, which further provides theoretical basis for design and optimization of mining.

郯庐断裂转换段新沂地裂缝成生机理及构造意义

新沂地区处于郯庐断裂带转换段的关键部位,自20世纪70年代以来在新沂地区共发现地裂缝灾害点28处。这些地裂缝以群发的形式发育在南马陵山以西、沂河—骆马湖以东的区域内,地裂灾害影响区面积达100 km^(2)。新沂地裂缝与地层结构、地震活动、地下水开采等因素有着千丝万缕的联系,对其研究形成了多种观点。利用实地调查与勘探手段,新近查明了新沂地裂缝的基本特征,它们具有走向一致性、纵向尖灭性、局部群发性等特点,且与邻近断裂(郯庐断裂带次级断裂F3)具有高度一致性,属于区域构造控制型地裂缝。以新沂地区地质构造为原型,构建了逆断层作用下地裂缝成生物理试验模型。试验结果表明,随着逆断层断距加大而依次呈剪裂段、离层段、弯裂段等发展过程。结合新沂地区“地堑地垒地堑”组合结构,新沂地裂缝的成因机制可概括为“跷跷板”构造模型,在构造应力、自重应力、地下水波动等作用下,下沉段受挤压,上升段因抬升而弯裂,从而形成地裂缝。研究新沂地区地裂缝,对揭示郯庐断裂带“北中南”段构造变化和“深浅表”部结构联系具有重要的指示意义。

稀土半胱氨酸螯合物对盐胁迫下黄瓜种子萌发和幼苗生长的影响

为探究稀土螯合物对盐胁迫下黄瓜种子萌发和幼苗生长的影响,以硝酸镧、半胱氨酸和半胱氨酸-镧作为试验材料,在NaCl溶液模拟的盐胁迫环境下进行培养皿发芽试验和盆栽生长试验。结果表明,盐胁迫显著抑制了黄瓜种子的发芽和幼苗的生长,而半胱氨酸-镧螯合物能显著缓解盐胁迫,提高种子发芽率和幼苗生长指标,与无盐胁迫处理无显著差异。半胱氨酸-镧处理的盐胁迫下黄瓜种子发芽率提高了10.9%,幼苗的地上部鲜质量增加了34.5%,地下部鲜质量增加了25.1%。此外,半胱氨酸-镧还能有效缓解盐胁迫下黄瓜幼苗的抗氧化系统,如丙二醛含量和超氧化物歧化酶、过氧化物酶、过氧化氢酶活性分别缓解了27.9%、33.9%、31.1%、37.0%,从而增强植物的抗逆性。因此,半胱氨酸-镧作为一种有效的盐胁迫缓解剂,具有提高黄瓜在盐胁迫环境下生长潜力的应用前景。

土石坝加高工程老坝防渗墙施工时机优选

针对老旧水库大坝加高工程中混凝土防渗墙的修建时机对其自身应力变形影响很大,可能对坝体防渗系统造成安全隐患的问题,以某土石坝加高工程为例,采用三维有限元法对大坝加高过程进行模拟计算,分析比较了不同施工方案下防渗墙的应力变形特性,以优选防渗墙施工时机。模拟计算结果表明:在加高坝填筑至215 m或此之前修建老坝防渗墙时墙体应力变形较小,此时竣工期与蓄水期防渗墙顺河向最大位移分别为-1.56 cm与4.91 cm,大主应力极值分别为1.01 MPa与1.67 MPa,小主应力极值分别为-0.41 MPa与-0.66 MPa,防渗墙与连接板接缝的切向错动和相对沉降变形极值分别为4.84 mm与8.11 mm,能够满足安全运行要求。相比加高坝填筑后期施工防渗墙,在加高坝填筑开始前或填筑至与老坝同高之前完成防渗墙的施工,可改善防渗墙的应力变形状态并降低防渗墙与连接板接缝的切向错动和相对沉降。

套孔应力解除法在老营盘隧道洞身段的应用

依托老营盘隧道工程,本文采用应力解除法对隧道洞身段Z1K17+880处进行现场地应力测试。由测孔内的原岩应变,利用岩石的本构关系来间接计算原岩应力,同时将取出的岩芯制成标准试件,进行室内试验以获取原岩的力学参数。计算结果表明,最大主应力大小为27.44MPa,倾角-16.56°,方位角192.60°,测点岩石抗压强度与隧道洞身最大主应力之比为0.24。测试结果表明隧道测点处属于极高地应力状态,隧道在施工过程中可能会出现软岩大变形。

考虑筑坝过程影响下的土石坝应力变形分析

应力变形分析一直是土石坝设计和施工中不可或缺的分析依据。文章以王家堡水库为研究对象,运用有限单元法深入分析了土石坝的分层施工过程及蓄水后的应力分布和变形特征,旨在探究土石坝在筑坝过程中的应力应变特性。计算结果表明,在建模过程中,考虑筑坝过程可使模型分析结果更贴近实际的土石坝应力变形状态,为类似工程安全提供参考。

Effect of La^(3+)on Activities of Antioxidant Enzymes in Wheat Seedlings under Mercury Stress

The effects of La(NO 3) 3 on the growth,activities of SOD,CAT and MDA content in shoots and roots of wheat seedlings under mercury stress were evaluated by the nutrient solution culture experiment. The results suggest that there is positive effect of La(NO 3) 3 on enhancing the activities of SOD,CAT,decrease of MDA content in shoots and roots of wheat seedlings during 0～5 d. But La(NO 3) 3 evens and cooperates with mercury when plants are too long under mercury stress. Mercury inhibits the growth of wheat seedlings more grievously.

盾构施工对周围土体应力扰动研究综述

随着地下隧道工程的增加,盾构掘进会改变隧道周围土体的应力状态,可能导致变形或沉降。探讨盾构掘进对隧道周围土体应力的影响对未来研究有很大的参考价值。文中总结现有成果,分类分析隧道周围水土压力变化、应力变化的影响因素及围压计算方法。研究表明盾构掘进引起的土压力和孔隙水压力变化具有相似规律,隧道周围应力变化受内外多因素影响,围压计算方法大多基于经验。缺乏全过程施工现场数据和大型模型试验,施工方法及地表荷载、地下水位等外部因素对土体应力的影响尚需深入研究,围压计算方法体系亟待完善。

Effects of La^(3+) on ATPase Activities of Plasma Membrane Vesicles Isolated from Casuarina Equisetifolia Seedlings under Acid Rain Stress

The effects of La^(3+) on the growth and the ATPases activities of plasma membrane(PM) vesicles isolated from Casuarina equisetifolia seedlings under artificial acid rain(pH 4.5) stress were studied. The results show that the height, length of roots, fresh weight and PM H^+-ATPase activites of Casuarina equisetifolia seedlings increase by the treatments of soaking seeds in LaCl_3 solutions with lower concentrations, and those can reach their peak values by treating with 200 mg·L^(-1) La^(3+). However, in comparison with the CK, those are inhibited by the higher La^(3+) concentrations; PM Ca^(2+)-ATPase activity is inhibited with the treatments of La^(3+). The results also reveal that the H^+-ATPase activity and the growth of cell enlarge have a remarkable positive correlation, and La^(3+) activating H^+-ATPase can facilitate plant growth. La^(3+) also can alleviate cytosolic acidification of plant under acid rain stress and indirectly maintain the stability of intracellular environment. In order to resistant to acid rain and accelerate the growth of Casuarina equisetifolia, the suitable range of La^(3+) concentrations to soak seeds for 8 h is 50～200 mg·L^(-1).

Effects of Lanthanum on Redox Systems in Plasma Membranes of Casuarina equisetifolia Seedlings Under Acid Rain Stress

The effects of lanthanum on some redox system(PMRS) properties of the plasma membrane(PM) vesicles from Casuarina equisetifolia seedlings under artificial acid rain(pH 4.5)stress were studied. The results show that there are NADH oxidase and EDTA Fe 3+ reductase, and nitrate reductase in the seedling PM, and they have different responses to soaking seeds for 8 h in a series of LaCl 3 solution. The NADH oxidase activities and the Nitrate reductase activities can be stimulated when La 3+ concentrations is in the range of 50～200 mg·L -1 , but their activities are inhibited or fluctuate by the higher La 3+ concentrations. The EDTA Fe 3+ reductase activities can be stimulated by La 3+ concentrations in the range of 50～400 mg·L -1 . The research also revealed that La 3+ reduces the relative permeability of membranes and have the function in protecting membranes under acid rain stress by the way of inhibiting the leakage of electrolyte.

基于碾压应力的土石坝料压实质量控制方法

坝料压实质量是土石坝施工质量控制的关键内容。在长河坝填筑现场进行碾压应力测试,建立土应力与坝料干密度关系模型,得出对应压实密度标准的土应力控制值;构建Midas三维有限元分析模型,模拟坝料碾压过程中的应力动态变化,根据土应力控制值来判断坝料压实质量。研究结果表明:坝料土应力与干密度之间存在较强的线性关系,其线性模型平均决定系数为0.9;对应坝料干密度控制标准,反滤料1上层、中层、下层土体的应力控制值分别为1.465、1.064、0.773 MPa,反滤料3上层、中层、下层的土体应力控制值分别为0.926、0.774、0.664 MPa;运用构建的Midas模型实时监测碾压应力变化,可知反滤料1和反滤料3分别在振碾6遍和8遍后整体达到压实密度标准。