Prediction model for occurrence of impact wave force

This study investigates the applicability of neural networks to predict whether impact wave force will act on the upright section of a composite breakwater. We employ a three-layered neural network whose units of input layer are h/L, H/h, d/h and B_M/h (h: the total water depth; L: the wavelength; H: the wave height; d: the water depth above the mound; B_M: the horizontal distance from the shoulder of mound to the caisson). Teach signals are 0.99 and 0.01 according to the cases of occurrence and absence of impact wave force, respectively. The neural network whose parameters are determined through self-learning can accurately predict whether impact wave force occurs.     

徐州活动断层探测项目主要断层活动性研究

对徐州市主要可能的发震断层开展了活动性探测及地震危险性评价工作,这对徐州市开展防震减灾工作具有重大意义.根据前人资料,分析了威胁徐州市区安全的主要5条隐伏断层,它们分别为幕集-刘集断裂、不老河断裂、废黄河断裂、班井断裂和邵楼断裂.同时根据徐州市活动断层探测项目的要求,针对这5条主要断层开展了浅层地震勘探、钻孔联合剖面探测、野外地震地质调查等相关工作,评价了这5条断层的活动历史、活动性质、规模、展布和地貌特征,及其最新活动时代.结果表明,废黄河断裂最新活动时代为中更新世中期,邵楼断裂最新活动时代为早更新世,这2条断层是目标区具备一定程度发震能力和地震危险性最大的断层.     

数据复分复接技术在数字化无线遥测地震台网中的应用

阐述了数据复分复接技术基本原理和级联方式。将MPX1059数据复用设备应用在合肥数字化无线遥测地震台网的中继传输中,取得了良好的效果。     

Geobag stepped spillway for check dams: A pilot study

Check dams are widely used worldwide for the soil and water conservation. Many of them have no spillways, resulting in frequent dam breach failures during heavy rainfall events. This paper proposes a new geobag stepped spillway for small check dams. The structure of the spillway primarily consists of a stepped chute created from geobags filled with local soil compacted and consolidated with a small amount of cement. The developed composite geosynthetic material exhibits water erosion resistance,...     

长短桩组合型复合地基优化设计方法研究

在软土地基上建造建(构)筑物需要进行地基处理,复合地基是一种行之有效的地基处理方式。工程上一般对地基浅层土的承载力要求较高,而深层只需满足下卧层强度要求即可。长短桩复合地基可做到浅层置换率高,深部置换率低,这样就合理地满足了软弱地基不同深度对承载力的要求。同时长短桩复合地基浅部置换率高,加固区复合地基模量大,深部置换率低,复合地基模量较低,正好适应浅部附加应力大,深部附加应力小的应力场,这样对减少软弱地基总沉降有利。本文探讨了长短桩复合地基优化设计方法,提出了长短桩复合地基优化设计数学模型,并利用复合形法求解优化设计数学模型,同时给出了优化设计计算算例,计算结果表明,此优化设计方法不仅可有效地保证长短桩复合地基设计方案技术上可靠,还可获得最佳的经济效益。     

过湿黄土砾石桩复合地基处理的试验研究

过湿黄土是指含水量较高的黄土。过湿黄土土体含水量高、饱和度大、压缩性高以及土体浸水后强度显著降低。其性质随土体含水量变化而变化,给工程建设带来一定影响。本文结合某高速公路过湿黄土地基砾石桩复合地基的工程实践以及原位测试,分析加固前后复合地基的强度和变形,研究过湿黄土的力学特性。并总结不同成桩工艺对过湿黄土复合地基的加固适用性以及地基处理要点。     

核电工程双钢板混凝土组合剪力墙研究综述

双钢板混凝土组合剪力墙在核电工程中的应用已成为大势所趋,对核电工程的建设起到了推进作用。本文分析了核电工程双钢板混凝土组合剪力墙的发展背景,总结了国内外双钢板混凝土组合剪力墙的抗震性能在试验、数值模拟及理论分析等方面的研究现状,并且对核电工程双钢板混凝土组合剪力墙在世界各国的研究进行了总结,最后对双钢板混凝土组合剪力墙的研究提出了一些关键问题,并对下一步的研究工作进行了展望。     

Seismic performance of square,thin-walled steel tube/bamboo plywood composite hollow columns with binding bars

A thin-walled steel tube/bamboo plywood composite hollow column with binding bars (SBCCB) was developed using transverse binding bars to reinforce a thin-walled steel tube and bamboo plywood composite hollow column. Low reversed cyclic loading tests were performed on 9 SBCCB specimens to observe the damage process and morphology in the SBCCBs. The effects of the slenderness ratio, the net cross-sectional area of the bamboo plywood, the assembly patterns of the cross sections, and the binding bars on the stress and seismic performance were investigated. The results show that the main failure modes of the SBCCBs were cracking of different adhesion interfaces at the base of the column and fracturing of the bamboo plywood. The cross-sectional assembly pattern has a significant effect on the failure modes; increasing the cross-sectional area and the slenderness ratio of the composite column will dramatically improve the seismic performance of the SBCCBs. SBCCBs have excellent elastic deformation and seismic energy consumption characteristics. The binding bars ensure the integrity of the specimen and inhibit the failure of the adhesion interface at the base of the column. Finally, based on the measurement of the axial pressure and the stress-strain curve within elastic range of the composite columns, a simplified mechanical model and a calculation method for bearing capacity was formulated. The calculation values of bearing capacity agree well with the experimental ones, and calculation method can be used to provide guidance for engineering applications of a SBCCB.     

Scour effects on bearing capacity of composite bucket foundation for offshore wind turbines

Abstract

Composite bucket foundation (CBF) is a wide-shallow foundation for offshore wind turbines, which can be transported and installed with the turbine as one unit at a one-step operation. Compared with deep pile foundations, its structural stability is more sensitive to the scouring by waves and currents. In this paper, a three-dimensional finite element model with CBF and surrounding soil is established to estimate the failure mode at different given soil scour conditions. The loading on CBF for offshore wind turbines is characterized by relatively small vertical loading V, larger horizontal loading H, and bending moment M, and the effect of erosion on bearing capacity of CBF is determined by using the fixed displacement ratio method. In addition, the failure envelopes of the CBF applied in H–M and V–H–M loading modes are obtained. Results indicate that the bearing capacity of CBF under horizontal loading and bending moment will be significantly reduced by the decrease in the embedded depth of CBF due to the scouring depth and extent, as well as the H–M, and V–H–M failure envelopes. The structural stability safety factor of CBF under different scouring conditions can be obtained through the three-dimensional envelope surface with respect to scouring depth and extent.