花岗岩变形破坏的阶段性模型--应力速度及预存微裂纹密度对断层形成过程的影响

依据对具有较高微裂纹密度的筑波花岗岩和极低微裂纹密度的花岗斑岩 2种极端的岩石标本、在等应力速率的快速加载 (约 6MPa/min)和蠕变加载 (轴向应力保持在约 95 %破坏强度 ) 2个极端的加载条件下的实验结果 ,讨论了预存微裂纹密度与加载速度对多晶质结晶岩变形破坏过程的影响。实验中利用高速多通道声发射波形数字记录系统 (每秒可记录多达 5 0 0 0个声发射事件的 32通道波形 ) ,获得了岩石标本破坏前微破裂活动的详细时空分布数据。声发射的发生率、震级 -频度关系中的b值及震源的空间分布揭示出岩石变形破坏过程中微破裂活动具有 3个典型阶段 :初期阶段、第 2阶段和成核阶段。尤其是在成核阶段 ,还观测到发生率和b值有大幅度前兆性起伏。一般而言 ,在相同加载条件下预存微破裂密度越高 ,或对同一岩石加载速度越慢 ,对应的断层成核过程就越长 ,因此最终破坏的可预报性也越高。为了进一步探讨微破裂活动的阶段性特征及其物理本质 ,还利用亚临界破裂扩展模型对声发射数据进行了理论分析     

岩石变形实验热红外观测系统

岩石变形导致的温度变化极其微弱 ,对观测系统与环境有严格要求。正确选择红外观测系统的参数 ,配备高灵敏度的温度场观测设备 ,以及有效地控制环境热背景决定了变形热红外实验结果的可靠性。在对噪声与干扰源进行详细分析的基础上 ,提出了进行热红外实验所需要的各主要设备的关键技术指标 ,并建立了一套相应的实验系统。典型材料样品实验表明 ,在考虑到变形热红外实验的各种特殊要求 ,认真选择观测设备 ,并进行了严格的误差校正之后 ,可以获得可靠的变形热过程信息     

微型桩组合抗滑结构受力机制的现场试验研究

针对有顶板连接的“八”字形微型桩组合结构,依托广大（广通至大理）线扩能改造工程,现场监测微型桩工作状态下轴力变化,对微型桩组合支护体系应用于分级开挖边坡加固的受力机制进行研究分析。结果表明：在滑坡推力作用下,各排桩桩身轴向力的分布形式不尽相同,沿推力方向依次呈现出反“S”型、“双弓”型和“S”型的分布规律;各排桩峰值轴力均为拉力,比例关系为：靠山侧桩:中间桩:靠路侧桩=2.5:4.1:3.2,其中靠山侧桩最大轴力出现在桩体下部,中间桩出现在中上部,靠路侧桩最大轴力出现在桩体上部;顶部承台对有斜桩的微型桩群的制约协调作用比一般的竖直桩群显著,水平荷载作用下的桩群易发生较大的挠曲变形,在群桩效应、坡体滑裂面等的综合影响下,引发桩体拉-压等受力形式的转变;组合结构的受力机制表现为先承受滑坡主推力的前两排桩受拉,第3排桩底部嵌固段受压,且随着持续推力作用受压区存在向上发展趋势;各单桩桩身轴力以拉力为主,有利于内部钢筋受拉优势的发挥。     

一种涵道双向泵叶轮浪流发电装置的研究分析

为解决海洋波浪能和潮流能耦合利用的问题,提升浪流发电装置的发电效率,上海海洋大学课题组设计了一种新型涵道双向泵叶轮浪流发电装置。主要对轴流泵的工作原理进行理论分析,阐述将轴流泵排水原理应用于浪流发电装置捕获浪流能的可行性,基于轴流泵叶片设计原理,设计出一种可以双向捕获浪流能的叶片。经数据仿真和水槽实验进行验证,得出涵道双向泵叶轮浪流发电装置可以在浪流流速v=0.5 m/s工况下浪即可启动,满足低流速启动要求,发电效率最高为23.7%。     

Study on Wave Dissipation of the Structure Combined by Baffle and Submerged Breakwater

This paper proposes a structure combined by baffle and submerged breakwater (abbreviated to SCBSB in the following texts). Such a combined structure is conducive to the water exchange in the harbor, and has strong capability on wave dissipation. Our paper focuses on the discussion of two typical structures, i.e., the submerged baffle and rectangular breakwater combined with the upper baffle respectively, which are named as SCBSB1 and SCBSB2 for short. The eigenfunction method corrected by experimental results is used to investigate the wave dissipation characteristics. It shows that the calculated results agree well with the experimental data and the minimum value of the wave transmission coefficient can be obtained when the distance between the front and rear structures is from 1/4 to 1/2 of the incident wave length.     

Effects of waterlogging,salinity and light on the productivity of Bruguiera gymnorrhiza and Heritiera littoralis seedlings

This study aimed to establish the effects of waterlogging, salinity and light on the early development of mangroves. Seedlings of Bruguiera gymnorrhiza (L.) Lamk. and Heritiera littoralis Dryand were exposed to 12 weeks of waterlogging, during which time growth and photosynthesis were measured every two weeks. The salinity of the water inundation ranged from fresh water to full-strength sea water (salinity 35). Seedlings were exposed to either full sunlight of 1 500 µmol photon m^–2 s^–1 (SD 397) at midday or shade conditions of 325 µmol photon m^–2 s^–1 (SD 40) of light at midday, to explore whether the plants would be differently affected by prolonged waterlogging in increased salinities and under different light conditions. Heritiera littoralis was more sensitive to waterlogging, salinity and light, displaying a least relative growth rate of 0.127 g g^–1 week^–1 (SE 0.032) under shade, and 0.025 g g^–1 week^–1 (SE 0.021) in full light; while under shade, photosynthesis continued only in fresh water, but photosynthetic yield decreased from 0.7 to 0.4 with increasing duration of waterlogging. By 12 weeks, all H. littoralis seedlings treated with any saltwater mixture had died. Bruguiera gymnorrhiza seedlings maintained a moderate rate of photosynthesis throughout inundation in both shade and full light, with yields of 0.7 and 0.3, respectively. Furthermore, B. gymnorrhiza survived waterlogging in up to 66% seawater, and maintained comparable relative growth rates of 0.164 g g^–1 week^–1 (SE 0.066) with 0.083 g g^–1 week^–1 (SE 0.065) and 0.074 g g^–1 week^–1 (SE 0.036) with 0.052 g g^–1 week^–1 (SE 0.037) under shade and in full light between fresh water and the highest salinity conditions, respectively. These results suggest that B. gymnorrhiza is broadly tolerant, making it a potential candidate species for restoring vulnerable mangrove forests.     

Fixed point automatic interpretation of bender-based G0 measurements

We present a new model updating technique for the automatic calculation of the small strain shear modulus of geomaterials, based on bender element experiments. The technique searches for the shear modulus that maximizes the correlation between the output signal obtained from the experiment and the output signal acquired from its computational simulation. Instead of conventional extremum finding algorithms, a fixed point technique is used to update the shear modulus at each iteration. This option increases substantially the attraction basin of the absolute maximum correlation and improves the convergence of the algorithm.     

Wind Tunnel Experiment of Anti-erosion Efficiency on the Sand Beds Coverd by Different Shapes of Roughness-Elementes

In order to study the relationship between the shapes of roughness-elements on sand beds and the surface sand activity inhibition, we chose six shapes of elements including spherical, triangular pyramid shape, cylindrical, square shape, pie and hemispherical shape by hand with equal quality kept. We carried out the experiment with the 10% coverage on the wind tunnel. The results revealed that ① the erosion and anti-erosion rate of spherical, triangular pyramid shape, cylindrical and square roughness-elements were better than the pie and hemispherical on the non-sand wind; ② On the sand-driving wind conditions, spherical, triangular, cylindrical covered beds became erosion to erosion-deposition with the increase of wind speed, and the erosion rate was increased with the wind speed. When the wind speed was more than 10 m/s, the sand-beds showed a strong erosion, and the pie and hemispherical elements’ resistance function were weakest; ③ No matter the non-sand wind or sand wind, the erosion rate was affected by the elements’ aspect ratio, height and spacing. The slender elements with a prominent upper edge were clearly superior to broad rounded elements.     

Simulation of morphological development of soil cracks in Yuanmou Dry-hot Valley region,Southwest China

Soil cracking is an important process influencing water and solutes transport in the Yuanmou Dry-hot Valley region of Southwest China. Studying the morphological development of soil cracks helps to further reveal the close relationship between the soil cracking process and water movement in such semi-arid regions. Here we report regular changes on surface morphology of soil cracks with decreasing water in four different soils (Typ-Ustic Ferrisols,Ver-Ustic Ferrisols,Tru-Ustic Vertisols and Typ-Ustic Vertiso...     

山区乡村房屋模型洪水冲击试验研究

洪水对山区乡村房屋冲击作用的试验研究成果,可为山区乡村房屋的抗洪设计和抗洪能力评价提供依据。试验主要研究到溃口不同距离处的乡村房屋所受的洪水冲击作用。采用3种开洞率模型进行试验,研究洪水在不同距离、不同开洞率的情况下对房屋结构的冲击荷载分布、冲击力大小以及冲击弯矩的影响,得出了荷载分布规律和冲击力、冲击弯矩的变化规律。研究结果表明,迎水面冲击荷载沿水平方向的变化无明显规律,沿竖直方向随着高度的增大而逐渐减小;冲击力随着房屋到溃口距离的增大而增大,而开洞率对其影响不明显;冲击弯矩、冲击作用力随着距离的增大而增大,随着开洞率的增大而减小。