超载预压塑料排水板加固软土地基试验研究

文章以我国东部沿海某新建机场地基处理工程为背景,通过动态监测加固地基的地表沉降、差异沉降、分层沉降、侧向变形、地下水位及孔隙水压力,探讨超载预压塑料排水板加固软土地基的变形规律及效果,为类似工程的优化设计和安全施工提供科学依据。     

地铁车站深基坑变形规律的三维数值模拟分析

以西安地铁某大型车站深基坑工程为背景,采用现场监测与三维数值模拟相结合的方法,研究了开挖过程中地铁车站深基坑的变形规律。结果表明,围护桩的变形直接关系到基坑的稳定和安全;开挖使得基坑周围土体下沉,地表沉降呈抛物线型;计算结果与监测结果基本一致,运用FLAC3D数值计算方法研究深基坑的变形规律是可行的、可靠的。     

宁波甬江特大桥钢横梁焊接工艺及其变形控制

宁波市甬江特大桥为双塔四索面叠合梁斜拉桥,斜拉桥由纵梁、横梁及小纵梁共同组成钢梁格体系,就中横梁现场制作工艺及焊接控制技术进行了阐述,并对其可行性进行论证。     

整体式桥梁结构特征分析

简要介绍了整体式桥梁的结构特征及主要部位的细部构造,以及修建整体式桥梁需要注意的条件。     

碳质板岩地层大断面隧道变形控制施工技术

双线大断面铁路隧道通过碳质板岩地层时,极易发生大变形。在现场工程实践和试验的基础上,文章从地质条件、地下水、支护参数、施工工艺等方面着重对碳质板岩地段变形演化机理及引发大变形的各类因素进行了分析,并提出了优化支护参数、加强锚杆对结构变形的控制、注浆纳入工序化管理等控制此类大变形的措施。     

基于层次分析的可拓学理论围岩大变形预测方法及应用

围岩大变形是地下工程建设中地质灾害的一种,为探讨准确而快速地预测围岩大变形,文章将层次分析法和可拓学理论方法与围岩大变形预测相结合,建立了基于层次分析的可拓学理论围岩大变形预测方法。该方法是在物元理论、可拓集合论和关联函数运算的基础上,通过选取能够反映和体现围岩大变形的几项重要参数指标(本文选取岩石单轴抗压强度、主应力值、强度应力比、弹性模量四项指标),建立围岩大变形预测的物元模型,结合层次分析法来确定各因素的权重值,通过实际围岩大变形等级的关联度计算,最终确定围岩大变形等级;并与模糊层次分析法取得的围岩大变形结果进行对比分析。该方法能够运用一定的基础数据对围岩大变形作出预判,对工程建设可起到一定的指导作用。     

Experimental and theoretical studies on the lateral collapse of mechanically lined pipes

The mechanically lined pipe, which consists of a thin non-corrosive liner and a carbon steel pipe, is an economical way to transport acidic fluid in offshore applications. However, it is prone to lateral loading and potentially develops plastic collapse and liner separation during the operational stage. The present study examines its crushing performance using small-scale 2-inch lined pipes manufactured by a customized hydroforming facility. The lined pipes comprised a seamless GB45 carbon steel tube and a grade T2 copper liner. Four ring specimens extracted from lined pipes and two single-layer rings were crushed on a universal testing machine in a quasi-static manner. The tube was found to develop an ovalized shape initially and then changed into a "∞" shape in the end. The carrier and liner were found to stay together throughout the crushing process, with slight liner separation taking place. The manufacture and lateral collapse processes were also reproduced with finite element models and nonlinear analytical formulation. The analytical model was established based on the principle of virtual work and nonlinear ring theory, assuming small strain and finite rotation. It showed that the analytical and numerical simulation results agreed with the experimental results. The influence of major parameters of the problem was also studied based on the full-scale lined pipe. Amongst other findings, manufacture-related plastic hardening is shown to affect the load-carrying capacity and the growth of separation during lateral collapse.