Ecological and agricultural productivity indices and their dynamics in a sub-humid/semi-arid region from central Mexico

Using precipitation data from a semi-arid region in the highlands of central Mexico, historical values of productivity are assessed. Production models based on climatic indices are discussed. An empirical rain simulation equation shows that it is possible to reproduce the expected values of productivity from observed ecosystems and agricultural yields. A graphical method is proposed to estimate intrinsic growth rate and maximum sustainable yield. Spatial rainfall variability induced by orographic effects, introduces a chaotic semicyclic behavior as expected in a logistic simulation equation. Resilience and predictable drought-productivity tendencies can also be derived from this model.     

水平地震作用下黄土多级高填方边坡动力响应规律及稳定性分析

为研究水平地震作用下黄土多级高填方边坡动力响应规律及稳定性，本文以某高填方边坡工程为背景，利用GeoStudio2012有限元分析软件建立模型进行分析，并对比分析多级高填方边坡与单级填方边坡动力响应结果。计算结果表明，边坡坡面和挖填交界面上动力响应规律表现为:位移幅值基本随着高程的增加而增加；速度幅值随着高程的增加先增大后减小再增大；加速度幅值随着高程的增加有减小趋势；多级高填方边坡动力响应规律与单级填方边坡动力响应规律不同，单级填方边坡位移幅值、速度幅值、加速度幅值均随着高程的增加递增；地震波在坡体内传播时，随着高程的增加具有滞后性。边坡稳定性随着地震加速度峰值的增大有所下降，相比静力作用，水平地震作用下边坡稳定性下降明显。本文相关研究可为西北地区黄土高填方边坡工程抗震提供一定理论依据。     

新型湿敏传感器的测试

本文讨论了正在开发中的耐水性高分子新型湿敏传感器的长期稳定性、初步证明这种传感器具有实用前景，所得结论对今后设计实用电路具有一定的指导意义。     

宝鸡市斗鸡台滑坡区滑坡地震稳定性计算与分析

本文是在斗鸡台滑坡区区域自然条件和地质地貌环境的广泛调查、工程地质勘探和可靠土质岩性力学性能试验［１］的基础上，用简布方法和“二分法”搜索法对滑坡体的整体稳定性和局部稳定性进行了计算评价。     

粘性力在地形变动力学模型演化过程中的作用

本文分别利用Ｌｙａｐｕｎｏｖ指数方法和特征值方法，对摸拟地震过程的线性粘弹性动力学模型的稳定性进行了分析，并讨论了粘性力在地形变动力学系统演化过程中的作用，采用Ｒｕｎｇｅ－Ｋｕｔｔａ格式的Ｍｅｒｓｏｎ修改方法模拟了在不同粘性系数时线性和非线性动力学系统的演化过程，得出了一些有意义的结论和认识。     

土质滑坡体破坏的突变模型

本文运用突变理论，分析了土质坡体破坏的两种方式:突变式破坏和渐变式破坏，建立了相应的在突变模型，从理论上解释了高速滑坡与低速滑坡的产生根源。对于受水文条件诱发的滑坡，提出了相应的判别准则。     

非静力平衡大气非线性层结对称运动的稳定性和突变

在假定了环境地转风具有水平和垂直的线性切变的情况下,考虑大气层结的线性和非线性切变的作用,建立了一个非线性常微分方程组,然后构造了一个Hamilton函数,通过讨论Hamilton函数的凸凹性,得到了非线性层结对称运动的不稳定判据,同时讨论了非线性层结对称运动产生突变的条件。     

山区边坡工程监测的探讨

以某煤矿边坡监测为例,较为详细地论述了在边坡监测中的布网方案、观测方法以及监测结果分析等问题。在位移观测时采用了改进的视准线法,并对该方法的精度进行了分析,结果证明其精度可以满足二等变形观测的要求。     

Undrained stability of a single circular tunnel in spatially variable soil subjected to surcharge loading

The stability of tunnels is an important problem in geotechnical engineering. Most of the previous studies dealing with the stability of unlined tunnels are deterministic in nature and do not consider the soil spatial variability. This study investigates the influence of spatial variability on the undrained stability of an unlined circular tunnel, using Random Adaptive Finite Element Limit Analysis (RAFELA). The effect of spatial variability is investigated for tunnels having two different ratios of γD/c_u, for different spatial correlation lengths and tunnel depths. The results indicate that the effect of spatial variability depends on γD/c_u and the depth of the tunnel.     

Undrained limiting pressure behind soil gaps in contiguous pile walls

Finite element limit analysis with plane strain condition is employed to determine the upper and lower bound solutions of the undrained limiting pressure behind soil gaps and the lateral force acting on a pile per unit length in a contiguous pile wall. Computed bound solutions confirm serious limitations of existing studies in predicting these two solutions. Predicted failure mechanisms and the arching effect behind soil gaps are discussed. A closed-form equation of the limiting pressure factor is proposed for a convenient and accurate prediction of the lateral force acting on a pile in contiguous pile walls in practice.