振动压实系统动力学模型及其解析

振动压路机和土壤在振动压实过程中构成一个完整的振动系统，机械和土壤之间存在着复杂的动态相互作用，土壤特性影响机械的动态响应，机械参数则决定土壤的压实效果。因此，建立完整的并尽可能接近实际的动力学模型是研究振动压路机压实效果和动态特性的前提和基础。本文以双驱双振铰接式振动压路矶为例，建立振动压实系统的动力学模型。     

Effect of geogrid reinforcement on soft and medium dense soils

The field tests were carried out to examine the reinforcement effect of a geogrid on various conditions of embankment height, the number of passages of vibratory roller, the number of reinforced layer of geogrid, and soil properties. The test results of the dynamic earth pressure indicate that the soil reinforced by geogrid is very effective to increase the stiffness of soil, especially in soft soil. The dynamic earth pressure ratio, which is defined as the ratio of dynamic earth pressure to self weight of soils, exponentially decreases as the embankment height increases. The dynamic earth pressure ratio increases up to 80% for soft soils reinforced by both one layer of geogrid in place of no reinforced soils and two layers in place of a single layer of geogrid.     

土壤对滴滴涕的吸附行为及影响因素研究

以采自现代黄河三角洲地区不同特性的土壤为研究对象,研究了滴滴涕(DDTs)在土壤中的吸附行为及土壤各特性参数对吸附行为的影响。实验结果表明:DDTs在该地区土壤中的吸附为弱非线性吸附,符合Lang-muir吸附等温方程,分配作用占主导地位;影响DDTs的吸附量的主要因素为土壤中有机质含量,其对Langmuir方程中最大吸附量的影响程度可用本文构建的定量方程描述;DDTs的吸附量与土壤的粘粒含量呈正相关,与土壤pH值及土壤可溶解盐含量无明显相关。本研究为构建现代黄河三角洲地区土壤中持久有机污染物的归趋提供数据支持。     

Evaluation of group effect of pile group under dragload embedded in clay

A simple semi-empirical analysis method for predicting the group effect of pile group under dragload embedded in clay was described assuming an effective influence area around various locations of pile group. Various pile and soil parameters such as the array of pile group, spacing of the piles (S), embedment length to diameter ratio of piles (L/D) and the soil properties such as density (γ), angle of internal friction (φ) and pile-soil interface friction coefficient (μ) were considered in the analysis. Model test for dragload of pile group on viscosity soil layer under surface load consolidation conditions was studied. The variations of dragload of pile, resistance of pile tip and the layered settlement of soil with consolidation time were measured. In order to perform comparative analysis, single pile was tested in the same conditions. The predicted group effect values of pile group under dragload were then compared with model test results carried out as a part of the present investigation and also with the values reported in literatures. The predicted values were found to be in good agreement with the measured values, validating the developed analysis method. The model test results show that negative skin friction of pile shaft will reach 80%–90% of its maximum value, when pile-soil relative displacement reaches 2 mm. Foundation item: Project(50679015) supported by the National Natural Science Foundation of China     

民勤灌区土壤特性与地表覆被的关系研究

选取民勤绿洲东湖灌区土壤的水分、全盐含量、碱解氮、速效磷、速效钾5个指标作为其空间变异的随机变量,进行实地采样和室内试验,采用统计插值分析的方法研究了该区土壤特性。结果表明:土地利用变化对土壤水分、养分、盐分有明显的影响;退耕还林地中出现了土壤水分的贫乏现象,电导率的最大值出现在荒地中,其次是退耕还林地,氮磷钾在不同的土地利用类型中表现出不同的特征。     

天山中部北麓丘陵地带土壤发生特性与系统分类

通过样地调查与土壤理化性质分析相结合对天山中部北麓丘陵地带的土壤特性进行研究,确定各剖面的诊断层和诊断特性及其在系统分类中的位置。结果表明天山中部北麓丘陵地带在系统分类中可划归为3个土纲4个土类;系统分类中土壤的分类位置与发生分类位置并不具有简单的一一对应的关系。     

深水S型铺管环境参数敏感性研究

本文以国内某深水海管S型铺设为例,对铺管过程中的环境参数敏感性进行了研究。在运用Orcaflex铺管过程分析计算的基础上,研究了波浪、海流、土壤特性等环境条件对管道内力、形态的影响。为深水海管的铺设设计及铺管船参数的选取提供了理论依据。     

开采沉陷区土壤特性空间变化及其作物响应

为了探究开采沉陷区土壤特性空间变化及其作物响应,以河南焦煤能源有限公司赵固二矿沉陷区耕地为研究对象,对不同沉陷部位的土壤含水量、全氮量、土壤微生物学特性(土壤呼吸速率、蔗糖酶和脲酶活性)以及作物的生长发育和产量性状进行研究.结果表明:在裂缝、附加坡度、积水等破坏形式的多重干扰下,沉陷区土壤含水量和全氮量均从坡上到坡下随着沉降深度的增加而增加;土壤水肥状况影响着土壤微生物学特性空间分布,土壤呼吸速率、蔗糖酶和脲酶活性大体呈现坡中>坡上>坡下规律;不同沉陷部位小麦生长发育及产量性状也受到不同程度影响,其中,坡下的小麦根系活力、叶绿素含量、净光合速率、株高、叶面积及产量性状均显著低于坡上和坡中的,而相较于坡中,坡上的小麦生长发育受抑制情况更为严重,致使最终产量显著低于坡中的.总之,开采沉陷区的土壤特性及植物生长具有空间异质性,且其空间变化特征与沉陷破坏形式密切相关.     

汤姆.普拉斯铁矿尾矿植被复垦研究

介绍了西澳汤姆．普拉斯铁矿为寻求最佳的尾矿植被复垦策略进行的一系列铁尾砂的物理化学土壤特性分析试验、种子发芽、营养缺省等生物试验与结果分析及对植被复垦策略进行讨论分析的经验。