Shaking table tests and numerical simulation of dynamic properties of underground structures

It is considered thai the damage of the underground structures caused by earthquakes is minor for a long time. However, the catastrophic damages induced by several recent earthquakes （e. g. Kobe earthquake in 1995 ） revealed that the study on the dynamic properties of the underground structures is indispensable. The dynamic behavior and damage mechanism of underground structure are analyzed by using shaking table tests （ both shallow-and deep-buried） and numerical simulation （3D FEM） including horizontal and vertical input motions, individually and simultaneously. From the results, the underground structure collapsed due to strong horizontal forces although vertical deformation is not negligible. The vertical excitation increases the response of structure, especially the stress and shear stress at the upper section; the soil influenced the property of soilstructure system. In the same excitation, the response in shallow-buried test is larger than deep case. Both overburden and vertical earthquake play important roles in the response of structure and those are two critical aspects in the design of the large-span underground structures, such as subway stations.     

Experimental study on ultrasonic propagation in water-based bentonite slurry

Drilling fluid is a common flushing medium used in pile foundation, geological drilling and petroleum drilling. Study on ultrasonic propagation properties in drilling fluid is of vital importance, not only for developing equipments to non-contact measuring concrete casting level for bored pile, but also for developing equip- ments considering drilling fluid as signal channel. The existence of clay particles makes the ultrasonic propagation and attenuation in drilling fluid much different from pure water. In order to know the relation among ultrasound frequency, slun-y density and depth, a series of laboratory experiments about ultrasound propagation in water-based bentonite slurry were finished. Wavelet method was adopted to process the gained original waves of ultrasonic propagation in slurry, so we knew the velocity and attenuation coefficient of ultrasound propagated in different drilling fluids with different density. The first group experiments shows that with density of drilling fluid increase, ultrasonic velocity will decrease but attenuation coefficient will increase if ultrasonic frequency keep constant. The second group experiments shows that the power of ultrasound will intensify in small bore hole, the attenuation coefficient is much smaller than theoretical value.     

Research on infiltration clogging effect and its application prospect in anti-seepage project

Clogging effect, as a new concept in geological engineering, is a phenomenon of permeability decreasing under seeping in reservoir dam foundation of the alluvial and diluvial deposits with deep and thick layer, coarse particle and high permeability in mountains-gully rivers of Tibetan Plateau. A clogging infiltration instrument has been designed successfully and a series of simulation tests have been done. Based on large amounts of data, it is confirmed that the existence of the clogging effect and the law of infiltration clogging is found out. Three indexes are proposed such as ＂optimal size of particle＂, ＂optimal size range of particle＂ and ＂characteristic pore＂, which are closely related with effect of infiltration clogging. The concept and results can offer a new idea to solve problems on anti-seepage of dam foundation in mountains-gully rivers environment and to study artificial clogging, meanwhile supplement of the concept of seepage deformation.     

Study of elastic-plastic damage model of cement consolidated soil with high organic content

On the basis of elastic-plastic damage model of cement consolidated soil, the authors took organic contents into reasonable damage variable evolution equation in order to seek relation between the organic contents and parameters in the equation, and established the elastic-plastic damage model of cement consolidated soil considering organic contents. The results show that the parameters change correspondingly with difference of the organic contents. The higher the organic contents are, the less the valves of the parameters such as elastic modulus （E）, material parameters （K, n） and damage evolution parameter （ε） become, but the larger strain damage threshold value （εd） of the sample is. Meanwhile, the calculation results obtained from established model are compared with the test data in the condition of common indoors test, which is testified with reliability.     

The Scavenging of Free Radical and Oxygen Species Activities and Hydration Capacity of Collagen Hydrolysates from Walleye Pollock(Theragra chalcogramma) Skin

Fish skin collagen hydrolysates (FSCH) were prepared from walleye pollock (Theragra chalcogramma) using a mixture of enzymes, namely trypsin and flavourzyme. The degree of hydrolysis of the skin collagen was 27.3%. FSCH was mainly composed of low-molecular-weight peptides and the relative proportion of <1000Da fraction was 70.6%. Free radical and oxygen species scavenging activities of FSCH were investigated in four model systems, including diphenylpicrylhy-drazyl radical (DPPH), superox-ide anion radical, hydroxyl radical and hydrogen peroxide model, and compared with that of a native antioxidant, reduced glutathione (GSH). FSCH was also evaluated by water-absorbing and water-holding capacity. The results showed that FSCH was able to scav-enge free radical and oxygen species significantly and to enhance water-absorbing and water-holding capacity remarkably. Therefore, FSCH may have potential applications in the medicine and food industries.     

Application of homotopy parameter inversion method in Miyun Reservoir

The large-scale convergence of homotopy parametric inversion method on the water quality model parameters calculated was used, with application in parametric inversion calculation of total phosphorus of Beijing Miyun Reservoir. Through calculated and compared the error of sedimentation rate by homotopy parametric in- version method and genetic inversion calculation method, the results indicate that homotopy parametric inversion method has good stability, calculating speed, and even if the initial selection away from the objective function, the solution still has a good convergence.     

古城区隐蔽工程施工中的障碍物及其排除法

在古城区隐蔽工程施工中，常碰到一些不同类型和分布特点的地下障碍物，其可分为：浜填土中的石，砖，混凝土碎块；原建筑物的基础，地坪，杂填土；各种管线；木桩等。排除障碍物的方法主要为机械法，人工法及联合排障法。排除障碍物后，需回填处理后方可进行下道工序，通常使地下障碍物的情况下，合理安排施工顺序，有的放矢地使用排障方法，如在排除障碍物过程中发生了突发事件，一定要果断处理，保证工程顺利进行。