To investigate the dynamic response characteristics of deep-water bridge pier foundations under the coupled action of wave and current,this study employed a battle spectrum to simulate the nonlinear effects of waves.MATLAB software programming was utilized to solve the time-history curve of wave-current forces.Based on the ANSYS software,a three-dimensional finite element model of the 3#pier structure of the Taihe Ganjiang Bridge was established,accurately simulating the response pattern of deep-water pile group under the coupled action of wave and current.Through transient dynamic analysis,the main conclusions provide guidance for the design and operation maintenance of deep-water bridge pier foundations.The main conclusions are as follows:the displacement at the top of the pier foundation shows a cumulative trend,and the displacement,stress,and strain at the pier body,pier bottom,and pile top exhibit nonlinear fluctuations.The deformation in the direction across the bridge is greatest at the top of the pier and gradually decreases downwards,with the minimum value at the pile top.The maximum values of stress and strain on the pier body are located at the still water level and the intersection of the pier bottom and the cap,respectively,with the minimum values at the top of the pier and the pile top.The result can provide theoretical guidance for the design and operation of deep-water bridge piers.
Highway in mountainous areas is vulnerable to landslide disasters,which may lead to the damage of subgrade.It is necessary to comprehensively evaluate the prevention and control effect of the treatment project when the subgrade is reconstructed after landslide damage.A reconstruction project of G326 highway damaged by a landslide in Guizhou Province was taken as an example.The landslide deformation and failure process in-duced by heavy rainfall was simulated.The prevention and control effect of different treatment schemes was an-alyzed and evaluated,such as the different prevented schemes of slope cutting,anti-slide pile and pile with pre-stress anchor cable.The results show that the deformation gradually expanded from the front of the landslide near G326 highway,to the head of the landslide with the increase of rainfall,and the plastic state occurred in the whole landslide body on July 8.After the combined treatment of slope cutting and anti-slide pile with pre-stress anchor cable,the maximum displacement of the landslide main area is 3.1 mm,and the maximum is 1.7 mm in the head of the landslide.The structure of anti-slide pile with prestress anchor cable optimizes the stress state of the landslide and makes the deformation of the whole landslide in a controllable and acceptable range,which ensures the safety of highway subgrade reconstruction.This research has some reference value for the highway reconstruction after a landslide.
煤矿覆岩离层突水危险性预测评价是制定科学防治水方案的基础和依据.为提高特厚煤层开采覆岩高位离层水害防控的精准性,首先根据离层与开采煤层之间距离及其与导水裂隙带范围的空间关系,判断出特厚煤层开采形成的高位离层位于导水裂隙带顶部附近,并分析了高位离层水涌突的3个基本条件,即相对封闭的可积水离层空间、离层补给水源和下渗的导水裂隙通道;然后在底板突水危险系数法的基础之上,提出了离层突水危险系数的概念,建立了高位离层水涌突危险性评价方法和危险性分级标准;最后采用该评价方法对郭家河煤矿1305工作面顶板离层突水危险性进行了评价,并根据郭家河煤矿和崔木煤矿其他工作面顶板离层突水危险性评价结果对该方法进行了验证.结果表明:郭家河煤矿1305工作面顶板离层突水危险性等级为安全,即不会发生离层突水;郭家河煤矿和崔木煤矿其他工作面顶板离层突水危险性评价结果与实际突水情况基本一致,验证了该评价方法的有效性.该研究成果可为黄陇煤田特厚煤层开采顶板离层水害的精准防控提供理论依据.
非开挖内衬技术广泛应用于城市地下管网的修复,对于保护城市环境和保障地下管网结构安全具有重要意义.然而原有管道的椭圆变形缺陷会降低新建内衬管的结构稳定性.将几种不同的椭圆变形管道内衬临界屈曲压力计算数学模型进行了对比,分析了现有规范中计算方法的不足,并基于最小势能原理和非线性理论,通过椭圆局部曲率方程推导出内衬的结构势能,建立起原有管道椭圆变形后柔性内衬管在外部静水压力作用下屈曲压力计算的数学模型;通过理论模型计算结果与有限元数值模拟结果进行对比,发现两者计算得到的内衬临界屈曲压力的计算误差基本上在10％以内;分析了不同椭圆度和内衬尺寸比(DR)值对内衬临界屈曲压力的影响规律,并通过与其他计算模型进行对比,验证了本文提出的计算模型在不同DR值内衬设计时的优势.
In order to solve the problem of insufficient water supply in Langqi Island of Fuzhou City, the Langqi branch（Mawei District） water supply pipeline of Tangban water diversion project is constructed across the Minjiang River channel.The inner diameter of the pipe is 1 200 mm, the length is 1 934 m, and the pipe material is Q345B steel pipe.In order to reduce the damage to existing ground facilities and ensure that the main navigation route of Minjiang River is unblocked, the horizontal directional drilling crossing construction method is adopted.The crossing stratum of this project is the soft and hard alternating stratum of rock and muddy clay.The first domestic 2 000 t level electric drive horizontal directional drilling machine independently developed is adopted, the new KY-100 horizontal directional drilling magnetic target guidance and positioning system is applied, and the internationally advanced dual drilling machine docking process is adopted to ensure the smooth implementation of the project.At the same time, in order to overcome the engineering difficulty related to complex crossing strata, difficulty in laying artificial magnetic field, long crossing distance, and tendency to ooze at the soil entry and exit points, technical means such as double casing, wall hook fishing, and casing cleaning and drilling tool unclamping are adopted to deal with the accidents in the hole such as bending and fracture of the drill pipe, which improvs the construction efficiency and reduces the impact of directional drilling on ground facilities and the environment.The relevant technical experience in this paper can provide data and technical support for the safe construction of similar projects in the future.
