Dynamic Response Analysis of High-rise Pile Cap-soil-structure under the Wave and Earthquake Action

Finite element software was used to simulate the internal force and deformation of high-rise pile cap-soil-structure under the wave and earthquake action. Meanwhile, wave force was calculated by using Morison equation, and the mechanical behavior of structure was simulated by inputing horizontal El-Centro wave. Then, the initial state and the state of the largest positive and negative acceleration were selected to study the structure according to the time history curve, and the displacement, bending moment, shear and axial force changes of pile foundation under wave and earthquake action were discussed, which was compared and analyzed with the structural response under the action of earthquakes solely. The result shows that the moment of front row of piles is biggest, and the force of pile bolck is the most dangerous; the axial force of the corner piles is the largest, and one of the center piles is the smallest under the action of wave and earthquake. When the wave forces and seismic forces are in the same direction, the displacement, moment, and shear force of pile bolck will be increased, on the contrary, the displacement, moment, and shear force of pile bolck will be decreased.     

An Approach for Estimating the Final Ultimate-bearing Capacity of Driven Pile In Soft Clay

The prefabricated pile,driven in soft clay,can squeeze the soil laterally in a certain scope around the pile,and the void ratio is reduced significantly;consequently,the shear bearing capacity is raised.But the soil parameter,which is used to estimate the capacity of pile,is reduced according to the soil state before the pile was driven.Then,a certain difference appears when the pile is working.The calculation result usually is partial to conservative.This paper analyzes the squeezing mechanism of the pile using the theory of cylindrical cavities expansion.And a formula,which is used to estimate the increment of shear bearing capacity of soil around the pile when excess pore water pressure from pile driving distributes completely,is presented based on the unique relation between the shear bearing capacity and the density of the soil.This formula can be used to estimate the final ultimate-bearing capacity of the pile.The calculated results by the proposed formula are in good agreement with those of the site measurement.     

Field Comparative Experimental Study on Bearing Capacity of Both Bored Pile with Branches and Plates and Column Bored Pile at the Same Site

Compared with column bored pile,the bored pile with branches and plates is a new type of piles with higher bearing capacity and lower settlement.Field comparative tests related to ultimate bearing capacity of both the bored piles with branches and plates and column bored piles at the same site in Huzhou city of province Zhejiang in China were studied through self-balanced method under static pressure.The results testify that,compared with column bored pile under the same geological conditions,the bored pile with branches and plates can obtain better economic benefit such as: increasing ultimate compressive bearing capacity and ultimate extraction bearing capacity used per cubic meter concrete over 75.3%and 118.9%respectively,while dropping consumption of reinforced concrete upwards of 41.9%and 44.1% respectively,reducing settlement and pile length under the same loading.The tests will present an objective reference to the new type of piles in both theoretic study and application to analogous engineering.     

Reflected Wave Isotraveling Time Circle and Its Application in Inverting Jointed Rock Masses

Joints are crucial factors in rock masses engineering,so using stress waves to invert joint attitude is a valuable practice.The stress wave emitted from a vibration source is reflected by joints and returns to the ground.A formula to calculate the reflected wave travel time was deduced using analytic geometry theory.In the formula,a direct relationship was established between a joint's real dip angle,real dip direction and the travel time at test spots on the ground.The reflected wave's isotravel time circle described by the formula has a clear conception and a definite meaning.Using the program on the MATLAB platform,this formula can be applied to invert the joint attitude by searching the center of the circle based on the measured travel time at the testing spots around the wave source.     

Reliability Ananysis of Bearing Capacity of Complex Pile Foundation

In this paper the, structural reliability theory is used to analse the reliablity of ultimatestates of complex pile foundation by means of a project example. further research is carried out on suchaspects as sensitivity of basic variables, of every resistant relationship between index of reliability andsafety fortor, influence on index of reliablity by platform which subjects to actions.     

Research on Index of Reliability for Bearing Capacity of Rock - Socketed Single Pile in Chongqing

Based on the data from in-situ 102 rock-socketed test piles in Chongqing in recent 10 years and utilizing the limit state equation of the dimensionless random variables,the reliability analysis of the bearing capacity of rock-socketed single pile is made and the scope of the target reliability of rock-socketed piles in Chongqing is calculated with both JC method and Monte-Carlo method respectively.Furthermore,the target index of reliability is suggested.Finally,the concept of reliability coefficient(to replace the load partial factor and the resistance partial factor) is given and the bearing capacity of the single pile is determined by utilizing optimization method.Besides,the practical limit state design equation using reliability coefficient is put forward for its advantage of incarnating the simple and practical principle and being easy mastered and understood by the designers.     

Time Effect Experimental Analysis of the Soil Arch Effect of Anti sliding Pile

Soil arching effect is important for stabilizing the soil behind anti sliding pile. The creep of soil mass will inevitably lead to the formation of soil arching, which has time effect. In this analysis, an indoor thrust pile model test is proposed. The characteristics of stress distribution in the soil and the time effect of soil arching behind anti sliding pile are analyzed. The experimental data acquired by the soil pressure cells arranged along the normal direction of the thrust show that soil arching effect is enhanced with the increase of thrust.The thickness of soil arch increases with time.And the data obtained by soil pressure cells arranged along the direction of the thrust show that the horizontal soil arching effect increases and then gradually extends.The scope of stress dispersion has very large growth along the normal direction as time goes on.     

Time Domain BEM for Wave Propagation Problems in Layered or Anisotropic Media and Its Application in Engineering

The dynamic response of an underground powerhouse under seismic waves is studied by time domain BEM for anisotropic media. The responses of displacements and stresses are evaluated. The effects of angle and frequency of incident waves and the degree of media anisotropy on dynamic response of the underground structure are analyzed in detail. Some important findings for engineering are obtained.     

Analysis of Wave Loads on the Grouping PileFoundation with Slab Merged in Water

In order to get the wave loads on pile groups with slab merged in water, an engineering approach was proposed. Three coefficients in terms of slab effect were discussed and a time -domain analysis of wave forces acting on piles was conducted. Wave diffraction from a slab was obtained by the potential theory and eigenfunction expansion method, while wave loads on piles were evaluated by Morison formula. The wave force on pile obtained by the proposed method and the numerical simulation are in good agreement, which shows a good reliability of the proposed method. The result shows that, owing to the size of slabs, there exist some differences in the changing rule of slab effect varying with the submerged depth. The resultant force decreases with the rise of incident wave number, and the changing trend of its acting point appears an inflection point at some wave number. The minimum force acting on piles lies in the meeting-wave side of the slab, while the maximum one arises at the back side or in the scope of 30 degrees between the axis of slab, which is perpendicular to the incident wave, and the back side. The presence of slab causes the deflexion and phase difference of inline force. Meanwhile, the grouping piles coefficient can be taken as 0.7.     

湖北省水资源供需平衡及其承载力

以湖北省为研究区域,运用水资源负载指数和水资源供需平衡模型,采用数理统计方法,定量计算和分析了湖北省近年来的水资源供需平衡态势以及湖北省市域尺度的水资源开发潜力;在水土平衡分析、水资源供需状况评价与水资源开发潜力评价的基础上,从资源平衡关系入手,采用水资源承载指数等指标,对2000—2012年省域与市域2个层面的水资源平衡状况进行了定量研究。结果表明：湖北省人均水资源量居全国平均水平。湖北省属于水资源利用程度较高、开发利用条件较好、水资源开发潜力较大的省区。湖北省水资源承载力有限,随着未来人口的增加以及工农业的快速发展,在现有的水资源量基础上,水资源短缺将会成为湖北省中东部城市的发展瓶颈。     

2014年春季内蒙古2次大风降雪寒潮过程分析

对于环流特征相似的寒潮过程,其爆发的方式、产生的天气和影响的区域基本相似,但个别寒潮过程却存在较大的差异,造成预报上的误判。针对此类特例,基于常规气象观测资料,自动站观测资料和NCEP逐6 h 1°×1°再分析资料,应用天气学分析和诊断方法,对2014年4月24日（过程1）和5月1日（过程2）2次寒潮天气过程的环流、系统和爆发的动力、热力学机制等进行对比分析。结果表明：2次过程北半球中高纬500 hPa环流形势均具有两脊一槽的环流特征。寒潮区域升温明显,前期平均温度分别比历史同期偏高1.0~7.3℃和0.1~10.7℃,500 hPa冷槽和强锋区均在新疆北部堆积、爆发南侵;2次过程在爆发方式和成因上存在着较大的差异,过程1中促使寒潮爆发流场为横槽转竖,槽前疏散结构和正涡度平流使低槽切断出低涡并东南移,冷平流中心移至槽前,横槽转竖寒潮爆发。过程2为低槽东移,冷槽移过阿尔泰山和蒙古高原加深东移,冷空气入侵内蒙古,寒潮爆发。虽然2次过程均造成了全区范围的强降温,但由于上述影响方式和成因的不同,使得大风、沙尘暴和降水呈现出不同的影响特点。寒潮过程中大风和沙尘暴的分布除与冷平流有关外,还与高空动量下传的地点和时间密切相关,对于寒潮过程中的降水而言,低层的温度层结及其水汽输送特点,决定了不同地区的相态变化和降水的量级。通过关注环流相似寒潮过程中的爆发方式和动力过程,对于正确预报寒潮天气造成的不同地区的降温、大风、沙尘和降水具有很好的借鉴意义。     

Analysis to On-off Voltage Wave and Its Parameter of Switched Power

To analyse the working parameter of switched power, this article introduces the circuit model of switched power and the shaping process of its on off voltage wave. Aiming at analyzing to the voltage wave and parameter, an "assistant compensation" method is put forward. Based on this method, the voltage wave and parameter of switched power are theoretically analyzed and imitated. The imitation results indicate that the method is afeasible and advance one.     

Bearing Characteristics of Large Diameter and Deep Rock-socketed Pile in Argillaceous Area of Guizhou Province

Based on the advanced technique of self-balancing test, the bearing characteristics of large-diameter deep rock-socketed pile（hr/d>30）, including the relation of load and displacement on top of it, side friction, the tip resistance and so on, under 10 thousand-ton load level in argillaceous area had been analyzed according to the report of static loading test on 2-piles of Balinghe River Bridge and 1-pile of Beipan River Bridge. The results indicate that Q-s curve of large diameter pile in mudstone declines slowly, and the weathering level of rock has great impact on tip resistance of pile. The ultimate bearing capacities of sandstone and dolomite in puny weathering are stronger than that of limestone in weak weathering; the side friction of pile is closely related to relative displacement of pile-soil interface, and the side resistance of pile in argillaceous dolomite needs smaller pile-soil relative displacement. Finally, the ultimate values of lateral resistance of pile and estimate of exploration report have been comparative analyzed.     

Experimental Analysis of Fire Resistant Performance of Concrete Frame with Damage Caused by Weak Earthquake

Two monolayer concrete frames with the same reinforcement, KJ1 and KJ2, were designed. KJ1 was designed to simulate low cyclic reversed loading test under weak earthquake. Besides, the fire response test, including temperature rising and lowing, was made by fixing the axial compression ratio of the column. For KJ2, the fire response test at the fixed axial compression ratio was made. The deformation response of the concrete frames in fire was studied. Comparative analysis of the apparent phenomenon, temperature curves, bearing capacity change of the frames were made based on the test results of KJ1 and KJ2. According to the simplified temperature distribution, the ultimate bearing capacity of the column under the high temperature was preliminarily determined. It is illustrated that the calculation results and finally test phenomenon are consistent according to the simplified section.     

Analysis of Fire Smoke Movement with Different Air Velocity at the Stair head to the Hall of a Metro Station

When a fire happens at the subway platform, the downward ventilation at the staircase which connects the hall and platform can prevent smoke spreading into the hall and provides guiding air for evacuation people. To investigate the influence of the ventilation rate on the smoke movement, the air velocity at the staircase was measured under three ventilation modes. Numerical model was established to simulate the real fire scenario. It is shown that the downward air velocity under fire is greater than that without fire, and the traditional design procedure without considering complex factors interaction in real fire scenario should be improved; when fire is near the staircase, smoke easily spills from the smoke screen to the concourse. And smoke concentration of concourse is even higher than that of platform because the hall is under air supply mode; when the fire locates at the public area of the platform, turning on the tunnel fans can increase the downside flow at the staircase. However exceeding high flow can produce disturbance and destroy the smoke stratification, so more area will be filled with smoke. Therefore, reasonable smoke management scheme is as important as smoke exhausting system capability.     

Experimental research on dynamical characterristics of rock in fei xianguan northeast in sichuan

Rock(sandstone, ash stone) in fei xian guan northeast Sichuan was used as rock sample,Experimental research on elasticity wave in room was done by testing technology of sound wave. The speed of elasticity wave and the dynamical elasticity parameter is calculated by the experiment. After the experiment, the physics mechanic character of rock is analyzed by experiment data.