富水砂层长距离顶管减阻泥浆性能研究

结合富水砂层顶管摩阻力特性以及高分子聚合物的作用机理,通过实验得到了如下优选泥浆配方:8%安信AX一级钠基膨润土+0.3%纯碱+0.25%聚丙烯酸钠+91.45%水。实验结果表明,该配比的泥浆在具有高黏度的同时,还具有很好的流动性和分散性,并且滤失量较小,综合性能最优。泥浆的表观黏度相比优化前提高了65%,滤失量相比现场取样泥浆降低了57%,满足现场砂土地层顶管的减阻泥浆性能要求。

深埋条件下曲线顶管顶力分析

在设计顶管时,顶力计算是非常关键的一环,是千斤顶、中继间、后背墙、顶进长度的重要设计依据。在深埋条件下,试图从普氏理论出发,考虑土体产生的压力拱效应,先计算顶管在直线顶进时的管侧摩阻力,再利用静力学理论对曲线顶管进行力学分析,分析曲线顶管顶力增大的原因,提出一个新的曲线顶管顶力计算公式。并利用实际工程实测结果与计算结果相比较,发现计算结果与实测结果较为接近。

Numerical Simulation on Thermal Stress Field in a Wide Slab Mould of Peritectic Steel Continuous Casting

A numerical simulation of the thermal stress field of the solidified shell in the mold during continuous casting of peritectic steel slab was calculated.The results showed,owing to the volume contraction caused by the peritectic reaction,the thermal stress on the wide surface of the solidified shell was larger for the peritectic steel slab than that for the non-peritectic steel,and the maximum thermal stress on the wide face was at the 200-400mm position away from the central line.With increment of slab width,the thermal stress increased and the maximum value moved towards the central line.In addition,the thermal stress was also affected by the casting operation parameters.In the present work,the proper drawing speed was around 1.2m/min for the wide slab of 3200mm×150mm,with the cooling intensity of 5500L/min and the superheat degree of 15℃ to 25℃.