A hybrid computational approach to formulate soil deformation moduli obtained from PLT     

Seyyed Mohammad Mousavi  Amir Hossein Alavi  Ali Mollahasani  Amir Hossein Gandomi 《Engineering Geology》2011,123(4):324

In this study, new empirical equations were developed to predict the soil deformation moduli utilizing a hybrid method coupling genetic programming and simulated annealing, called GP/SA. The proposed models relate secant (E_s), unloading (E_u) and reloading (E_r) moduli obtained from plate load–settlement curves to the basic soil physical properties. Several models with different combinations of the influencing parameters were developed and checked to select the best GP/SA models. The database used for developing the models was established upon a series of plate load tests (PLT) conducted on different soil types at various depths. The validity of the models was tested using parts of the test results that were not included in the analysis. The validation of the models was further verified using several statistical criteria. A traditional GP analysis was performed to benchmark the GP/SA models. The contributions of the parameters affecting E_s, E_u and E_r were analyzed through a sensitivity analysis. The proposed models are able to estimate the soil deformation moduli with an acceptable degree of accuracy. The E_s prediction model has a remarkably better performance than the models developed for predicting E_u and E_r. The simplified formulations for E_s, E_u and E_r provide significantly better results than the GP-based models and empirical models found in the literature.  相似文献   

Empirical modeling of plate load test moduli of soil via gene expression programming     

Ali Mollahasani  Amir Hossein Alavi  Amir Hossein Gandomi 《Computers and Geotechnics》2011

New empirical models were developed to predict the soil deformation moduli using gene expression programming (GEP). The principal soil deformation parameters formulated were secant (E_s) and reloading (E_r) moduli. The proposed models relate E_s and E_r obtained from plate load-settlement curves to the basic soil physical properties. The best GEP models were selected after developing and controlling several models with different combinations of the influencing parameters. The experimental database used for developing the models was established upon a series of plate load tests conducted on different soil types at depths of 1–24 m. To verify the applicability of the derived models, they were employed to estimate the soil moduli of a part of test results that were not included in the analysis. The external validation of the models was further verified using several statistical criteria recommended by researchers. A sensitivity analysis was carried out to determine the contributions of the parameters affecting E_s and E_r. The proposed models give precise estimates of the soil deformation moduli. The E_s prediction model provides considerably better results in comparison with the model developed for E_r. The simplified formulation for E_s significantly outperforms the empirical equations found in the literature. The derived models can reliably be employed for pre-design purposes.  相似文献   

侧限压缩下砂土的细观力学特性及其形态分析   总被引：1，自引：0，他引：1       下载免费PDF全文

曹亮  刘文白  李晓昭  赵晓豹  张辉 《地质论评》2011,57(4):591-599

本文基于室内固结试验,自行设计加工了土体受到轴向压力和侧限条件时,对土的细观结构进行观测的细观结构观测固结仪.通过对中砂半模固结仪试验的宏观变形场分析选择了细观特征观测点,发现中砂的位移场类似于抛物线形,位移量最大区总是发生在上透水石的底面中心处;利用MiFas图像软件对中砂压缩过程中的显微图像进行处理,分析了中砂试样...  相似文献   

循环冻融条件下安山岩和花岗岩的物理力学特性试验研究   总被引：5，自引：0，他引：5  

刘华  牛富俊  徐志英  林战举  许健 《冰川冻土》2011,33(3):557-563

结合青藏铁路块石护坡路基处于青藏高原特殊的气候条件,对用于青藏铁路护坡的两种主要岩石（花岗岩和安山岩）进行循环冻融试验.结果表明:两种岩石在经历了数次冻融循环后都出现了微细裂纹;声波监测表明,超声波速同冻融循环周期呈指数下降关系,显示了冻融循环对岩石风化的影响以及循环后岩石物理力学参数变化的趋势.结果说明,花岗岩的冻融...  相似文献   

长江源北麓河流域多年冻土区热融湖塘形成对高寒草甸土壤环境的影响   总被引：10，自引：7，他引：3  

王一博  吴青柏  牛富俊 《冰川冻土》2011,33(3):659-667

通过对长江源北麓河流域多年冻土区热融湖塘及湖塘影响周边条件下高寒草甸土壤理化性质的比较研究,结果表明:热融湖塘的形成对高寒草甸土壤环境产生了明显影响,热融湖塘形成对土壤质地、含水量、容重以及土壤养分等产生强烈改变,尤其表层土壤;土壤机质(SOM)、全氮(N)等化学物质和其他养分成分在不同退化的土壤中都有所改变.有机质和...  相似文献   

弯曲河段床面分形特征及床面阻力试验研究   总被引：1，自引：0，他引：1       下载免费PDF全文

江磊  陈立  周银军  闫涛 《水科学进展》2011,22(4):502-508

根据概化水槽试验的结果,引入河床表面分形维数(以下简称BSD)用于河床表面形态的量化研究,并对BSD的计算方法、弯曲河道的分形特征及BSD值的大小与床面阻力的关系进行了探讨.结果表明,BSD的大小在大尺度上能够反映河段在纵向上的深泓起伏程度和横向的滩槽差,在小尺度上能反映河床表面相对的冲淤幅度,即弯曲河段床面具有明显的...  相似文献   

建筑边坡岩体分类及其应用合理性研究     

方玉树 《中国地质灾害与防治学报》2011,22(4):89-95

当前的建筑边坡岩体分类不含外倾软弱结构面控制的边坡和倾倒崩塌型破坏的边坡,把岩体完整程度、结构面结合程度、结构面产状、岩石坚硬程度和地下水发育程度作为分类因素。对这种分类及其应用存在的问题进行了分析。研究表明,这个分类在分类规律、分类对象、分类因素等方面均不合理,也没有实际意义,已有的关于岩体性状的通用分类和专用于边坡的单因素分类对于边坡工程已经够用。提出了取消专用于边坡的岩体综合分类的建议。  相似文献   

黑河日径流量混沌变化特性的研究——Ⅲ最大李雅普诺夫(Lyapunov)指数的确定     

陈引锋  马长铃 《地下水》2011,33(3):136-138

通过对黑河日径流量变化规律的探索,重点论述最大李雅普诺夫指数的确定方法,计算结果表明:黑河日径流量时间序列的最大李雅普诺夫指数为0.002012,大于零,可以判定黑河日径流量时间序列具有混沌特性.  相似文献   

平湖地区ZST构造X井平湖组储层特征研究     

张萍  宋刚练  余学兵 《海洋地质译丛》2011,(2):43-46,81

以平湖地区ZST构造X井区有限的钻井资料为基础,利用岩石铸体薄片、扫描电镜、X-衍射等测试技术手段,对该井区平湖组的岩石学特征、粒度、储层物性等方面开展了系统研究。研究揭示：该储层的岩石类型主要为长石岩屑砂岩,属中孔中渗砂岩储层。平湖组储层物性受沉积环境和成岩作用的双重影响。沉积环境控制储层物性,潮间带和潮下带发育的潮道砂、砂坪是较好的储层;成岩作用对储层物性优劣起主导作用,胶结作用导致储层物性变差,溶蚀作用（长石溶蚀作用）改善了本井平湖组的储层物性。  相似文献   

南黄海中部沉积物物理性质与压缩波速相关性分析     

程净净  傅命佐  孟祥梅  刘乐军  阚光明  刘保华 《中国海洋大学学报(自然科学版)》2011,(Z1):331-336

根据南黄海中部海底沉积物柱状样的实验室土工试验测试结果,分析沉积物的物理特征,并通过实验室方法获得沉积物压缩波速,探讨物理参数与压缩波速的相关关系,得到经验公式。结果表明:该区域沉积物以淤泥和淤泥质黏土为主,具有含水率高、孔隙比大、塑限高等特征;物理参数与压缩波速之间有较好的相关关系,密度、孔隙比、含水率、塑限、液限及塑性指数与压缩波速的相关性最明显,其中,密度与压缩波速成正比相关关系,而孔隙比、含水率、塑限、液限和塑性指数与压缩波速成反比相关关系;以沉积物天然密度和塑性指数为自变量的双变量回归分析方程能更好地表达沉积物物理特性与压缩波速的相关关系。  相似文献