局部液化地层范围及埋深对隧道地震上浮的影响研究

杭州地铁4号线甬江路站—锦江站区间施工时需穿越大范围的可液化地层,为降低隧道在地震作用下上浮破坏的潜在风险,该区间选线时将隧道埋深进行了增大,从而使隧道部分处于非液化土层。为了研究在地震作用下盾构隧道局部液化地层范围以及隧道埋深对隧道上浮的影响,并对隧道调整后的抗震效果做出评价,采用有限差分软件FLAC^(3D)数值模拟与振动台试验相结合的方法,对处于不同液化土层分布范围、不同埋深的隧道地震上浮情况进行了数值分析及模型试验,研究结果表明:隧道液化地层范围越小,隧道上浮位移越小;当隧道埋深达14 m、隧道液化地层范围小于隧道范围一半时,隧道只发生轻微上浮;隧道设计时应尽量避免使隧道完全处于可液化地层中,可采取液化与非液化地层组合或增大埋深的方式,提高隧道结构的抗震安全性。

粉砂地基覆盖层上闸基的地震液化分析

本文以Ⅶ度地震地区的某进水闸工程为例,利用有限元软件Abaqus对未加固的闸室地基和碎石桩加固的闸室地基建立液化度三维计算模型,分别采用顾淦臣动孔压模型和剪应力对比法对闸室地基进行了液化范围的判定。分析表明：未加固的粉砂地基与碎石桩加固地基在地震循环剪切作用下,都发生了地基液化现象。粉砂地基的土体颗粒在1.0~3.0m深处最容易达到液化而被破坏,而经碎石桩加固的粉砂地基,其与土体颗粒的接触部位在1.0~5.0m深处最易发生液化。碎石桩加固地基虽然提高了粉砂地基的承载力,但是在抗震液化方面仍然不足,地基处理设计时要综合承载力和地震液化两个要求同时考虑。

黄河下游宽河段闸前微差爆破开槽冲刷成渠方法研究

在黄河下游宽河段,由于主流摆动,常造成引水口脱溜,导致引水不能正常进行。本文提出的微差爆破开槽冲刷成渠方法,是在湿滩的情况下,用微差爆破技术形成可以冲开的最小引槽,引水冲刷,最终形成闸前引水渠的成渠方法。本研究表明,爆破开槽冲刷成渠方法可以解决宽河段河道主流与闸门之间的引水渠畅通问题。爆破试验表明,控制微差爆破的最大爆破深度和一次最大引爆药量,可以有效地控制爆破引起的饱和土液化范围;用爆破技术可以在湿滩上形成成型的引槽,成型引槽的空槽状态可以保持20分钟左右,此后,爆破形成的槽壁泥沙压实层可以被返回的剩余超静空隙水压力冲散,由水和细沙组成的稀泥浆从槽壁涌出,形成“浆河”。试验和计算表明,爆破形成的引槽,存在细沙从槽壁压出回填入槽的特点,有利于快速冲刷形成引渠。

基于能量耗散原理的振杆密实可液化地基范围研究

为了建立振点间距和振动时间的计算方法,对振杆密实可液化地基加固范围进行理论预测。针对已有基于能量法的液化评估方法不适用于地基密实设计的现状,发展了基于地震容量曲线的液化评估能量方法,并对其应用于振杆密实设计的适用性进行了评价;建立了基于能量耗散原理的振杆密实模型来预测液化范围并与实测结果进行对比。研究结果表明:门槛剪应变为0.01%时预测液化范围与现场实测差别较大,基于稳定振速预测的液化范围小于基于峰值振速的预测值,达到最终液化范围的振动时间增加;门槛剪应变为0.015%时基于峰值振速预测的液化范围与现场实测差别较小,推荐使用;振动液化用时30 s左右,实际施工中无需留振;高振动频率下的能量传递效率降低,液化边界远小于共振频率下的加固范围。

Conversions of fuel-N, volatile-N, and char-N to NO and N_2O during combustion of a single coal particle in O_2/N_2 and O_2/H_2O at low temperature

Oxy-steam combustion is a promising next-generation combustion technology.Conversions of fuel-N,volatile-N,and char-N to NO and N2O during combustion of a single coal particle in O2/N2and O2/H2O were studied in a tube reactor at low temperature.In O2/N2,NO reaches the maximum value in the devolatilization stage and N2O reaches the maximum value in the char combustion stage.In O2/H2O,both NO and N2O reach the maximum values in the char combustion stage.The total conversion ratios of fuel-N to NO and N2O in O2/N2are obviously higher than those in O2/H2O,due to the reduction of H2O on NO and N2O.Temperature changes the trade-off between NO and N2O.In O2/N2and O2/H2O,the conversion ratios of fuel-N,volatile-N,and char-N to NO increase with increasing temperature,and those to N2O show the opposite trends.The conversion ratios of fuel-N,volatile-N,and char-N to NO reach the maximum values at 〈O2〉=30 vol%in O2/N2.In O2/H2O,the conversion ratios of fuel-N and char-N to NO reach the maximum values at 〈O2〉=30 vol%,and the conversion ratio of volatile-N to NO shows a slightly increasing trend with increasing oxygen concentration.The conversion ratios of fuel-N,volatile-N,and char-N to N2O decrease with increasing oxygen concentration in both atmospheres.A higher coal rank has higher conversion ratios of fuel-N to NO and N2O.Anthracite coal exhibits the highest conversion ratios of fuel-N,volatile-N,and char-N to NO and N2O in both atmospheres.This work is to develop efficient ways to understand and control NO and N2O emissions for a clean and sustainable atmosphere.

Manifestation If Substance Molecular Structure in Temperature Effects of Light Scattering

DCMSL （depolarization components of molecular scattering of light） have been studied within the wide spectral range （0-200 cm-1） and in the temperature intervals （20-200 ℃） in toluol （C6HsCH3） and aniline （C6HsNH2）. It has been shown that when a liquid is heated and temperatures approach to critical ones, a significant contribution of DCMSL is made by vibration motion of molecules. The special properties of the temperature-frequency behavior of DCMSL spectra are discussed from the view point of hindered rotation of liquid molecules with consideration of intermolecular interaction.