桩底加载法静载试验在大直径嵌岩桩工程中的应用研究

静载试验新方法—桩底加载法静载试验 ,应用于重庆市的大直径嵌岩桩 ,解决了此类工程现场测试获取设计参数的一大难题 ,为进一步完善大直径嵌岩桩桩身侧阻力与端阻力的计算理论提供了依据。     

OCEAN BOTTOM SEISMOMETER AND ONSHOREOFFSHORE SEISMIC EXPERIMENT IN NORTHEASTERN SOUTH CHINA SEA

Three-component Ocean Bottom Seismometers, portable land stations and marine air gun seismic sources were used to carry out an onshore-offshore deep seismic profile in northeastern South China Sea. This profile, orientated in NNW-SSE, was as long as 500 km and perpendicular to the strike of regional tectonics. The offshore data were processed in Taiwan Ocean University using a number of available software and the onshore data were analyzed in South China Sea Institute of Oceanology by new-written programs and public software. Preliminary results show that the seismic data are in good quality and contain rich information of deep structure. Seismic phases, e.g. Pg, PmP and Pn, are identified in the offset range 5～220 km, which will provide an important dataset for the deep crustal structure and oil-gas basin evolution studies of this region.     

Geomorphologic characteristics and origin of the valley bottom troughs at the site of Three Gorges Dam

This paper describes valley bottom troughs of the Changjiang River and infers the geomorphologic development of troughs. Based on the morphology of the troughs, the following conclusions are drawn. (1) The deep troughs on the Three Gorges valley bottom are formed by river downcutting along the structural zones on the background of regional tectonic uplift at about 40-30 ka BP. (2) When river downcutting occurred in the river bed of Changjiang, the jets current (particularly eddy current) with a large number of pebbles ground and eroded the valley bottom, resulting in trough formation and deepening. Meanwhile, water currents with gravels and pebbles eroded the bank and the left wall of No.76 trough as well as the right wall of No.77 trough by striking, scouring, horizontal and vertical grinding. (3) The depth of the trough is mainly determined by the intensity of the water current and the consistency of bedrock against erosion, and is not controlled by the altitude of the sea level as the base level of erosion.     

斜井与平峒贯通点坐标的计算方法

在矿山贯通工程中,采矿设计人员常常根据矿体的地质构造及矿山生产的实际需要,给出巷道掘进的基本思想,测量人员必须根据这一要求进行准确的再设计,以确保贯通的正确实施。本文就某矿9坑斜井与14坑主运平烟贯通点N平面坐标的计算说明这一过程。     

黄河揭底冲刷现象的计算分析

黄河中游的高含沙洪水常常引起黄河的"揭河底"冲刷。通过对黄河"揭河底"现象的分析,建立了"揭河底"冲刷的物理模式,进而导出了"揭河底"冲刷的力学方程和临界水沙条件,其计算结果与实测"揭河底"冲刷的水沙条件相一致。通过该方程与水沙条件的分析,进一步验证了散粒体泥沙起动的流速公式。这两个公式的导出对研究高含沙洪水引起的河床演变以及泥沙起动规律具有重要的理论价值。     

Microseismicity around rupture area of the 1944 Tonankai earthquake from ocean bottom seismograph observations

Along the Nankai trough, southwestern Japan, the Philippine Sea plate (PSP) is subducting beneath the Eurasian plate, and large interplate earthquakes have occurred repeatedly with a recurrence interval of about 100-200 years. The most recent large thrust event in the eastern Nankai trough off Kii Peninsula was the 1944 Tonankai earthquake. In this region, current seismicity is very low and hypocenters are not determined accurately by the land seismic network. We conducted microseismicity observations around the rupture area of the 1944 Tonankai earthquake using ocean bottom seismographs (OBSs). Hypocenters were determined using a 2-D seismic velocity structure model based on an airgun-OBS seismic survey. Results obtained show that the seismicity was relatively active near the trough axis. These earthquakes may relate to deformation of the subducting Philippine Sea plate. On the other hand, microseismicity in the rupture area of the 1944 Tonankai earthquake was very low. This low-level seismic activity in the co-seismic rupture area of the 1944 Tonankai earthquake likely relates to a single large asperity off Kii Peninsula.     

立井冻土爆破的理论与实践

结合冻土爆破破坏特征,从理论上分析探讨了立井冻土掘进掏槽爆破和光面爆破机理及参数设计,再在实验室中进行模型试验研究,然后将试验结果应用于工程实践去验证和完善. 结果表明:立井冻土掘进爆破以浅眼多循环为宜,眼深Lb =1.2～1.4m;直眼掏槽、周边光爆,较为合理的掏槽参数为:槽眼布置圈径%D%=1.0～1.2 m,眼距a=500～700 mm,单位耗药量q=2.2～2.8 kg*m-3;较为合理的光爆参数为:周边眼距E=500～600 mm,光爆层厚度W＝500～700 mm ,炮眼密集系数m＝0.8～1.2,炮眼装药集中度%q%L=120～160 g*m+-1,空气垫层或空气间隙不偶合装药结构.     

Numerical simulation of earthquake excited dam-reservoirs with irregular geometries using an immersed boundary method

In this work, a ghost-cell immersed boundary method is proposed for the hydrodynamic response of earthquake excited dam-reservoirs. The numerical method employs a second order accurate two-step projection algorithm including compressibility effects in pressure field due to earthquake. The effects of reservoir bottom absorption are treated by introducing damping terms into the momentum equations. Hydrodynamic response of earthquake excited dam with a sloping face is simulated to demonstrate the accuracy of the present numerical method. Numerical results compared with previous numerical and analytical solutions show that the present immersed boundary method can accurately compute the hydrodynamic forces on inclined and curved dam faces including the effects of water compressibility and reservoir bottom absorption for the possibility of resonance. The proposed numerical method was shown to have significant advantages in computational time and memory usage for the hydrodynamic simulation of large dam-reservoirs with arbitrary geometries. Hydrodynamic forces on a double curvature arch dam subjected to real earthquake induced ground motion are also simulated to demonstrate the capability of the method.     

图像增强技术在X射线医学影像中的应用

目的:对X射线影像进行图像增强。方法:应用多种互补的图像增强方法,首先采用拉普拉斯法来突出图像中的细节,使用梯度法突出边缘,然后用平滑后的梯度图像掩蔽拉普拉斯图像,通过高提升滤波得到锐化图像,再使用灰度变换增大锐化图像的灰度动态范围。将本文算法的结果与传统图像增强算法的结果进行比较,该算法对X射线影像增强效果显著,相比传统算法有很大的优势。增强后的图像细节更加清晰,优于传统算法的实现效果。结论:本文算法对医学X射线影像具有一定的理论和实际应用价值。      

Recent surface marine sediments of Cocos Island in Costa Rica

Subtidal sediments of Isla del Coco(Cocos Island),Costa Rica were described in their grain size,sorting,organic matter,and carbonates from 27 dredge samples(3-75 m),collected in April 2010.The organic matter range between 1.37-3.31%and carbonates presented a mean of 74±17%.The sorting was moderately or poorly.The grain size ranged between 0.1-1.1mm.The pattern is that sediment change from inner to mouth of bays.Carbonates and gravel fractions increased offshore and organic matter have high values inner the bays.Input of vegetal debris and mud was from the rivers of this island covered with rain and cloud forest.