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为研究深部巷道围岩在地下水作用下的长期蠕变力学特性,采用自主研制的深部软岩五联流变试验系统,开展不同含水率(0%、0.8%、1.6%、2.4%、3.3%)下砂岩吸水软化单轴压缩试验及单轴蠕变试验。通过试验结果研究表明：砂岩的单轴抗压强度、弹性模量和蠕变破坏应力与含水率呈指数下降关系,蠕变破坏应力与单轴抗压强度的比值在0.76～0.84之间;砂岩衰减蠕变阶段时间随着含水率的增加而减少,随应力水平的增加而增加。径向应变比轴向应变先进入稳态蠕变阶段,破坏应力下径向应变的加速蠕变阶段开始时间要先于轴向应变;基于稳态蠕变速率曲线确定了砂岩的长期强度,径向稳态蠕变速率确定的值略小于轴向,长期强度与含水率之间满足负指数关系;将蠕变试验中径向应变与轴向应变之比定义为μc,提出了基于μc值的岩石长期强度确定方法且μc值与含水率无关,对于本次砂岩样品可以认为μc值大于0.3时样品会在一定时间内发生加速蠕变破坏;随着含水率的增加,样品破坏形态由单斜面剪切破坏逐渐演变至X状共轭斜面剪切破坏。研究结果为地下水作用下巷道长期稳... 相似文献
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The present study was conducted to determine the ef fects of elevated pCO_2 on growth, photosynthesis, dark respiration and inorganic carbon acquisition in the marine microalga D unaliella salina. To accomplish this, D. salina was incubated in semi-continuous cultures under present-day CO_2 levels(390 μatm, p HN BS : 8.10), predicted year 2100 CO_2 levels(1 000 μatm, p HN BS : 7.78) and predicted year 2300 CO_2 levels(2 000 μatm, p H NBS : 7.49). Elevated pCO_2 significantly enhanced photosynthesis(in terms of gross photosynthetic O_2 evolution, ef fective quantum yield(ΔF/F' m), photosynthetic efficiency( α), maximum relative electron transport rate(r ETRm ax) and ribulose-1,5-bisphosphate carboxylase/oxygenase(Rubisco) activity) and dark respiration of D. salina, but had insignificant effects on growth. The photosynthetic O_2 evolution of D. salina was significantly inhibited by the inhibitors acetazolamide(AZ), ethoxyzolamide(EZ) and 4,4'-diisothiocyanostilbene-2,2′-disulfonate(DIDS), indicating that D. salina is capable of acquiring HCO ˉ 3 via extracellular carbonic anhydrase and anion-exchange proteins. Furthermore, the lower inhibition of the photosynthetic O2 evolution at high pCO_2 levels by AZ, EZ and DIDS and the decreased carbonic anhydrase showed that carbon concentrating mechanisms were down-regulated at high pCO_2. In conclusion, our results show that photosynthesis, dark respiration and CCMs will be af fected by the increased pCO_2/low p H conditions predicted for the future, but that the responses of D. salina to high pCO_2/low p H might be modulated by other environmental factors such as light, nutrients and temperature. Therefore, further studies are needed to determine the interactive eff ects of pCO_2, temperature, light and nutrients on marine microalgae. 相似文献
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