Advanced Materials Research Vols. 594-597

Abstract: In order to discuss how the different forms of steel impact on seismic behavior of steel reinforced high-strength concrete(SRHC) L-shape short-pier shear wall, four different steel forms SRHC L-shaped section short-pier shear wall members with low reversed cyclic loading were simulated by ABAQUS. The four steel forms were steel bar, solid-web steel, truss-type steel and hole-type steel. The result show that: different steel forms can significantly impact on the seismic performance of SRHC L-shaped section short-pier shear walls and the seismic capacity range from high to low as follow: with solid-web steel, with hole-type steel, with truss-type steel and reinforced.

Abstract: To reveal development law of seismic subsidence of loess, through in-situ explosion test at one loess site, ground settlement and layered underground settlement were monitored, by which the time-space-domain development of seismic subsidence of loess are gained. Furthermore, the time-domain development law of seismic subsidence in different directions is analyzed, so as the variation characteristics of layer-settlement and its contribution rate, and the development law of seismic subsidence distribution in the horizontal direction. The time-domain development of seismic subsidence of loess consists of rapidly growing stage and slowly growing stage. The former is under blasting ground motion, and its seismic subsidence ratio approaches to 46.5% invariably. While in the later stage, development of seismic subsidence ratio can be described by power function with index of 0-1. And, seismic subsidence distribution and contribution rate of layer-settlement are varying with time, which are consistent to the time-domain development law of seismic subsidence.

Abstract: Based on the diseases disposal project of Longmen Tunnel in the Fujian provincial road 206, the seismic reinforcement measure of mountain tunnel cavity was studied in this paper. The seismic stability of the mountain tunnel to deal with the cavity behind the lining was calculated and analyzed under the two common disease reinforcement measures, by using a 3-D finite difference method. And the optimal reinforcement scheme also had been determined. The results show that mortar bolt and cover arch can change the maximum principal stress spectral characteristics of surrounding rock, which is beneficial to the seismic resistance. And the results also show that mortar bolt has slightly effect on the bending moment stress of lining.

Abstract: Frame connections imminently need to be strengthened for deficient seismic-resistance in early time. The paper presents research results of strengthening connections through concrete jacketing, bonding steel plate, prestressing, wrapped steel and FRP by scholars in home and abroad, contrasts their strengthening effect and gives the future research aspect.

Abstract: Abstract: In this paper, we simulated two-dimension numerical on the strong ground motion in Lanzhou basin through the hybrid scheme based on the pseudospectral method (PSM) and finite difference method (FDM). We base on a focal of 20 km deep and a profile of 5 layers is used as model to analyze the site response and the peak displacement of strong ground motion. The results show that the hybrid PSM/FDM method for seismic wavefield simulation combines with advantages of PSM and FDM and makes up for the disadvantage of them, so this method can process well the calculation of the discontinuous medium surface, then the calculation accuracy is similar to PSM. Through the wavefield simulation it is known that the peak ground displacement (PGD) of the vertical is larger and the influence of surface wave at the basin edge is more obvious than the horizontal.

Abstract: This paper uses the equivalent linear model of Hardin-Drnevich and the dynamic effective stress analysis method, gets the safety coefficient of stability, the liquefaction zone distribution and seismic residual deformation of diversion dike under the seismic action of SL1 and SL2. The paper also uses the minimum safety coefficient and average minimum safety coefficient of the whole process of earthquake to evaluate the stability of diversion dike under different seismic action and compares the results. Compared with SL2, the diversion dike foundation liquefaction range is smaller than under the SL1 seismic action, so it is does not affect the normal use of diversion dike structure. When meet the seismic action of SL2 which is appears about one time in a ten thousand, diversion dike will produce bigger deformation, but the integral slip to the heart of canal will not happen, so the use of water of the nuclear power plant is safe. The result has a certain reference value and guiding significance for the similar engineering design.

Abstract: In the light of heavy seismic landslide disasters in the valley city of loess area, 104 typical loess landslides caused by the 1654 Tianshui(Ms 8.0), 1718 Tongwei(Ms 7.5) and 1920 Haiyuan(Ms 8.5) earthquakes were studied, main landslide type and basic characteristics of seismic landslide in the valley city were analyzed. The landslides in the valley city of loess area are divided into three types: homogeneous loess landslide, loess interface landslide and loess-mudstone cutting layer landslide. Through the investigation and analysis of earthquake risk, the suggestion about the 22 dangerous landslides in Tianshui is given. The study is expected to supply scientific basis for seismic landslide disaster prevention and reduction in valley city of loess area.

Abstract: Taking the landslides triggered by the 2008 Wenchuan Earthquake as examples, their dynamic responses with different epicenter distances due to single and combined action with regionality and spatial heterogeneity of the Primary and Secondary waves were simulated by applying the Universal Distinct Element Code software. The results shows that the slope suffered from the combined action between P and S waves appears instability prior to the slope under single action of P wave. With the epicenter distance increasing, the key controlling factor resulting in the slope failure varies from the combined seismic action between P and S waves to the single seismic action of the P wave. As for the formation mechanism of slope instability, coupled action between the vertical and horizontal seismic forces results in the slope dynamic failure with key action varying from the vertical to the horizontal one. Finally, the initial instability originates always at slope shoulder due to the peak ground acceleration amplification effect and the variation trend of the slope mechanical parameters on its fracturing of the seismic action.

Abstract: During the long-term operation of concrete dam, the cracks in concrete dam might have propagated. Aiming at this situation, based on the comprehensively consideration of the evolution and abnormality situation of concrete dam crack, a method to determine the warning value of the opening of concrete dam crack was proposed. First, the time-effect of crack opening was extracted and its variation law was analyzed, according to this, the occurring time of the unstable propagation of crack was determined. Then, the warning value of crack opening after the last propagation of crack was determined by use of the low probability method. Apply this method to analyze the measured data of a concrete dam crack; the warning value of crack opening was determined successfully; this shows that this method has certain application value.

Abstract: Investigate on the information of river basin and river way in Dianbei Provisional Detention Basin, use the Preissmann four point implicit difference scheme for the discrete solution of Saint Venant equation, and establish the mathematical model of flood routing for hydraulic. Analyze and evaluate the backwater of construction in Dianbei Provisional Detention Basin, and the Yongding River flood control criteria are combined. The result indicates that water level caused by the implementation of construction project is very small, and the influence to flood control in flood detention area and the adjacent area is very limited, so the project will not affect the flood release in detention basin.