利用非稳定流理论判断崔庄煤矿田岗断层导水性

日岗新层是滕县煤田中的一个比较大的断层，其落差为160—470m。田岗断层从崔庄煤矿的中部穿过，对崔庄煤矿煤层的开采影响较大。本文在补勘资料的基础上，运用非稳定流法判定了田岗断层的导水性，对煤矿的安全生产起到了重要的指导作用。

泰斯模型的统计分析求解

本文利用统计分析来求解水文地质参数,原理简单,解是唯一的。其基本思想是利用非稳定流抽水试验获得的s-t系列资料,以泰斯公式为参考模型,建立试验系列的非线性统计模型,求解导水系数T和贮水系数μ 。统计模型既可利用目前先进的软件辅助求解,亦可利用一台可编程计算器完成计算。本文借助一个实例,应用MATLAB语言的统计分析工具的多元回归分析模块进行求解,获得了理想的结果。

供水水文地质勘查中水文地质参数确定与选取问题

青海地区供水水源地以山间河谷或山前冲洪积扇第四系卵砾石潜水含水层为主,采用不同方法计算的含水层参数值相差数倍至十多倍,特别是渗透系数和给水度选取的合理与否是资源评价的重点和难点。笔者对近十年来完成的供水水源地勘探典型项目参数确定方法及选取问题进行分析研究后,认为潜水含水层给水度用容积试验法确定的给水度较为符合实际,用抽水稳定流理论确定的渗透系数明显偏小,用非稳定流理论的观测孔雅各布和水位恢复半对数直线法确定较为准确。

对《公路排水设计规范》中几个有关地下排水水力计算公式的讨论

文章对JTG/TD 33—2012《公路排水设计规范》中涉及潜水含水层渗沟、渗井的流量计算选择承压水影响半径经验公式联立求解进行了探讨;分析了按阿勃拉莫夫井壁允许进水流速估算渗井半径的欠合理性;提出不透水层的横向坡度较陡时的渗沟流量计算公式中假设的水文地质条件有待进一步论证。同时提出应按卡明斯基近似式计算不透水层和水平底板有一定夹角的流量计算。

天津软土地区降水数值仿真技术研究

天津地区水文地质及工程地质情况特殊,为典型的软土地区,地层分布不连续,承压水和潜水相互贯通,降水设计难度大,本文通过有限元软件,利用非稳定流理论,对地铁车站按照1:1进行建模,本文得出了天津软土地区降水水位降深的规律和对周边环境的影响。

利用典型区域抽水试验结果进行水资源评价

利用抽水试验结果进行水文地质参数计算 ,是在短时期内获得水资源评价结果的一种捷径而可靠的方法。

Stability analysis of shallow tunnels subjected to seepage with strength reduction theory

Based on strength reduction theory,the stability numbers of shallow tunnels were investigated within the framework of upper and lower bound theorems of limit analysis. Stability solutions taking into account of water seepage were presented and compared with those without considering seepage. The comparisons indicate that the maximum difference does not exceed 3.7%,which proves the present method credible. The results show that stability numbers of shallow tunnels considering seepage are much less than those without considering seepage,and that the difference of stability numbers between considering seepage and without considering seepage increase with increasing the depth ratio. The stability numbers decrease with increasing permeability coefficient and groundwater depth. Seepage has significant effects on the stability numbers of shallow tunnels.

Fluid–solid coupling analysis of rock pillar stability for concealed karst cave ahead of a roadway based on catastrophic theory

In order to study the mechanism of water inrush from a concealed, confined karst cave, we established a fluid–solid coupling model of water inrush from a concealed karst cave ahead of a roadway and a strength reduction method in a rock pillar for preventing water inrush based on catastrophic theory. Fluid–solid coupling effects and safety margins in a rock pillar were studied. Analysis shows that rock pillar instability, exerted by disturbance stress and seepage stress, is the process of rock pillar catastrophic destabilization induced by nonlinear extension of plastic zones in the rock pillar. Seepage flow emerges in the rock pillar for preventing water inrush, accompanied by mechanical instability of the rock pillar. Taking the accident of a confined karst cave water-inrush of Qiyi Mine as an example, by studying the safety factor of the rock pillar and the relationship between karst cave water pressure and thickness of the rock pillar,it is proposed that rock pillar thickness with a safety factor equal to 1.5 is regarded as the calculated safety thickness of the rock pillar, which should be equal to the sum of the blasthole depth, blasting disturbance depth and the calculated safety thickness of the rock pillar. The cause of the karst water inrush at Qiyi Mine is that the rock pillar was so small that it did not possess a safety margin. Combining fluid–solid coupling theory, catastrophic theory and strength reduction method to study the nonlinear mechanical response of complicated rock engineering, new avenues for quantitative analysis of rock engineering stability evaluation should be forthcoming.

The dynamic stability of the flow in a meander channel

The meander channel is one of the most common channel patterns in nature.The characteristics of the flow and sediment in a meander channel which have significant effect on the development of watercourse are important subjects in river dynamics.The transition of the flow patterns in a meander channel concerns with the development mode of the channel pattern and the river regime including the generation conditions of the three-dimensional coherent vortex and secondary flow,the hierarchical scale of coherent vortex in different flow conditions,the large-scale turbulent eddy structure adapted to a meander,etc.In this paper we study the laminar flow instability of the two-dimensional channel in a meander channel.It is essentially different from that in a straight channel:The neutral curve will move forward and the critical Reynolds number will decrease.The flow is unstable in response to a wider range of the disturbance wave number,or the laminar flow instability can happen more easily.The above results could not be obtained in the traditional hydrodynamic stability theory so that our work in this paper would make up for the deficiency and blank in this aspect.

Analysis of the secondary instability of the incompressible flows over a swept wing

The crossflow instability of a three-dimensional (3-D) boundary layer is an important factor which affects the transition over a swept-wing.In this report,the primary instability of the incompressible flow over a swept wing is investigated by solving nonlinear parabolized stability equations (NPSE).The Floquet theory is applied to study the dependence of the secondary and high-frequency instabilities on curvature,Reynolds number and angle of swept (AOS).The computational results show that the curvature in the present case has no significant effect on the secondary instabilities.It is generally believed that the secondary instability growth rate increases with the magnitude of the nonlinear mode of crossflow vortex.But,at a certain state,when the Reynolds number is 3.2 million,we find that the secondary instability growth rate becomes smaller even when the magnitude of the nonlinear mode of the crossflow vortex is larger.The effect of the angle of swept at 35,45 and 55 degrees,respectively,is also studied in the framework of the secondary linear stability theory.Larger angles of swept tend to decrease the spanwise spacing of the crossflow vortices,which correspondingly helps the stimulation of 'z' mode.

Stability and self-adaption character of turbulence coherent structure in narrow-deep river bend

In a meandering fiver, a certain scale of turbulent vortex dominates the development of fiver morphology, making the river bend with s particular curvature. This kind of vortex is denoted as ＂bend-forming vortex＂. The coordinated relationship of bend-forming vortex and meandering fiver channel is then known as ＂self-adaption feature＂ of rivers. With these two concepts, this paper investigated the stability and self-adaption character of coherent vortex in the U-shape river bend with a constant curvature. On the basis of fluid mechanics theory and in consideration of turbulent coherent vortex as disturbance, the growth rate and the wave number response range of coherent vortex in meandering rivers with different curvatures were calculated in this paper. Moreover, the responses of different scales of coherent turbulence structure to river bend parameters were analyzed to explain the mechanism of fiver bend maintenance. These methods could provide a theoretical basis for further investigation on fiver meandering.

Modeling the effect of time delay in budget allocation to control an epidemic through awareness

The emergence of any new infectious disease poses much stress on the government to control the spread of such disease. The easy, fast and less expensive way to slow down the spread of disease is to make the population be aware of its spread and possible control mechanisms. For this purpose, government allocates some funds to make public aware through mass media, print media, pamphlets, etc. Keeping this in view, in this paper, a nonlinear mathematical model is proposed and analyzed to assess the effect of time delay in providing funds by the government to warn people. It is assumed that suscep- tible individuals contract infection through the direct contact with infected individuals; however the rate of contracting infection is a decreasing function of funds availability. The proposed model is analyzed using stability theory of delay differential equations and numerical simulations. The model analysis shows that the increase in funds to warn people reduces the number of infected individuals but delay in providing the funds desta- bilizes the interior equilibrium and may cause stability switches.

Secondary instability control of compressible flow by suction for a swept wing

The crossflow instability of a three-dimensional boundary layer is a main factor affecting the transition around the swept-wing.The three-dimensional boundary layer flow affected by the saturated crossflow vortex is very sensitive to the high frequency disturbances,which foreshadows that the swept wing flow transition will happen.The primary instability of the compressible flow over a swept wing is investigated with nonlinear parabolized stability equations (NPSE).The Floquet theory is then applied to the analysis of the influence of localized steady suction on the secondary instability of crossflow vortex.The results show that suction can significantly suppress the growth of the crossflow mode as well as the secondary instability modes.

A New Lattice Model of Two-Lane Trafc Flow with the Consideration of the Honk Efect

In this paper, a new lattice model of two-lane traffic flow with the honk effect term is proposed to study the influence of the honk effect on wide moving jams under lane changing. The linear stability condition on two-lane highway is obtained by applying the linear stability theory. The modified Korteweg-de Vries （KdV） equation near the critical point is derived and the coexisting curves resulted from the modified KdV equation can be described, which shows that the critical point, the coexisting curve and the neutral stability line decrease with increasing the honk effect coe^cient. A wide moving jam can be conceivably described approximately in the unstable region. Numerical simulation is performed to verify the analytic results. The results show that the honk effect could suppress effectively the congested traffic patterns about wide moving jam propagation in lattice model of two-lane traffic flow.

Dynamic Transition and Pattern Formation in Taylor Problem

The main objective of this article is to study both dynamic and structural transitions of the Taylor-Couette flow, by using the dynamic transition theory and geometric theory of incompressible flows developed recently by the authors. In particular, it is shown that as the Taylor number crosses the critical number, the system undergoes either a continuous or a jump dynamic transition, dictated by the sign of a computable, nondimensional parameter R. In addition, it is also shown that the new transition states have the Taylor vortex type of flow structure, which is structurally stable.

Turing patterns in a reaction-diffusion epidemic model

In this paper, we investigate the spatiotemporal dynamics of a reactio^diffusion epi- demic model with zero-flux boundary conditions. The value of our study lies in two aspects： mathematically, by using maximum principle and the linearized stability theory, a priori estimates of the steady state system and the local asymptotic stability of positive constant solution are given. By using the implicit function theorem, the exis- tence and nonexistence of nonconstant positive steady states are shown. Applying the bifurcation theory, the global bifurcation structure of nonconstant positive steady states is established. Epidemiologically, through numerical simulations, under the conditions of the existence of nonconstant positive steady states, we find that the smaller the space, the easier the pattern formation; the bigger the diffusion, the easier the pattern formation. These results are beneficial to disease control, that is, we must do our best to control the diffusion of the infectious to avoid disease outbreak.