泡沫轻质土与水泥土搅拌桩在厚软土桥头路基处理中的应用

泡沫轻质土具有重量轻、固化后自立、耐久性高等优点,应用泡沫轻质土是目前解决道路改扩建路基处理、管线开挖回填处理、软土地基处理和桥头路基不均匀沉降等工程问题的有效措施。针对厚软土地基桥头路基处理,文中结合实际工程案例,分析了泡沫轻质土材料在厚软土桥头路基处理中的设计和应用,阐明了泡沫轻质土的特性和正台阶填筑设计施工方法。结果表明,采用泡沫轻质土进行厚软土桥头路基处理对控制地基不均匀沉降具有显著效果。

厚软土车行通道窄长大型沉井施工工法

以横琴新区国际居住区市政基础设施及配套工程(S1、S4片区)为依托,通过方案分析、理论分析及试验验证的研究方法,给出了厚软土车行道窄长大型沉井的施工方法。该方法具有施工简单、速度快、安全可靠、对周围建筑物影响小的特点,还具有防水效果好、经济效益高等优点。重点研究了厚软土车行通道窄长大型沉井施工技术、沉井支护格栅式地基加固技术、长条形沉井内隔墙加固技术等。与SMW法相比,本文提出的沉井法节约107253.40元。采用沉井法在厚软土层施工支护结构,保证工期,提高质量和安全,节省投资,简化施工,以最经济的成本达到满足现场施工需求的目的。

厚软土覆盖层区域高桩码头引桥桩基选型研究

高桩码头引桥部分一般位于河漫滩上,而对常见的厚软土覆盖层河漫滩,合理地选择安全、经济的桩基型式,是工程设计中必须深入研究解决的问题。结合工程实例,对厚软土覆盖层河漫滩地段地质特点进行分析,并从桩基施工难度、结构安全性及实施经济效果等角度,对钻孔灌注桩和PHC管桩两种桩型进行研究比选。根据比选结果,选择陆上施打PHC管桩作为引桥桩基。施工完成后,通过桩基检测,工程质量良好,经济效益明显。

大面积超厚软土处理的设计与施工

结合具体工程实例,简要介绍了碎石桩作为排水通道在超厚软土处理中的设计原理及施工技术。

深厚软土地区钻孔桩智能化施工及质量控制关键技术

随着时代的发展,人们对于建筑施工的要求也越来越高,对建筑的需求也越来越大。建筑的质量有很大一部分原因与建筑的地区是有所关联的,例如土地偏硬的地区就会有土地偏硬地区的建筑施工方式,这些地区的建筑物的施工技术较为简单,但是由于土地资源的稀缺,因此一些厚软土地区也需要进行建筑施工开发,在这些厚软土地地区进行建筑施工对于建筑工作者而言是一个挑战,在挑战者,建筑施工者可以利用智能施工技术进行质量的控制。文章以在深厚软土地区的施工为主题,研究了钻孔桩智能化施工的技术。

超厚软土区管桩复合地基不均匀沉降病害处治

超厚软土中管桩复合地基桩与土的刚度差异显著,其上修建的道路易出现不均匀沉降病害。以超厚软土管桩复合地基不均匀沉降病害项目为研究对象,提出了截桩置换填充材料加整体式筏板的修复方案,并对不同方案进行了数值计算分析。分析表明:填充材料弹性模量≤1 MPa时,道路整体沉降偏大;填充材料弹性模量>50 MPa时,道路不均匀沉降偏大、边桩筏板底部脱空;填充材料弹性模量在10~12 MPa之间、且泊松比小于0.3时处治效果最佳。经工程应用证明,在沉降较小的桩顶上填充适宜弹性模量和泊松比的材料加整体筏板方案,可有效地解决应力集中和不均匀沉降问题,研究结果具有一定的工程指导意义。

爆破挤淤堤软土未被爆穿的应对措施

随着海岸带开发利用的逐渐增加,具有建设海工工程的优良地质条件的厂址日趋减少,工程厂址开始着眼于近岸的孤岛,但是这种厂址往往伴随着超厚的淤泥,对地基处理的深度提出了更高的要求,本文以某工程爆破挤淤处理超厚软土为例,介绍地基处理的深度未达要求时可采取的应对措施。

Design parameter optimization of beam foundation on soft soil layer with nonlinear finite element

Finite element method was performed to investigate the influences of beam stiffness, foundation width and cushion thickness on the beating capacity of beam foundation on underlying weak laminated clay. The comparison between numerical results and results from field test including plate-bearing test and foundation settlement observation shows reasonable agreement. According to the numerical results, the beam width, length, cross section and cushion thickness were optimized. The results show that the stresses in subgrade soil decrease greatly with increasing the cushion thickness and width of foundation. However, the foundation settlement and influencing depth of displacement also increase correspondingly under conditions of relatively thinner cushion thickness. For the foundations on underlying weak layer, increasing foundation width merely might be inadequate for improving the bearing capacity, and the appropriate width and cushion thickness depend on the response of subgrade. A comparison between rigid and flexible beams was also discussed. The influence of a flexible beam foundation on subgrade is relatively smaller under the same loading conditions, and the flexible beam foundation appears more adaptable to various subgrades. The proposed flexible beam foundation was adopted in engineering. According to the calculation results, beam width of 2.4 m and cushion thickness of 0.8 m are proposed, and a flexible beam foundation is applied in the optimized design, which is confirmed reasonable by the actual engineering.

Rational concrete cover of prestressed concrete beams and slabs for fire resistance

As the influence of the ratio of the characteristic value of structural resistance to that of frequent combination effect, K, on the thickness of concrete cover of prestressed concrete （PC） beams and slabs for fire resistance is not considered sufficiently in design criteria for concrete structures in China and other countries at present, numerical analyses were carried out by ANSYS software on unbonded prestressed concrete （UPC） oneway simply-supported and continuous slabs and beams, and bonded PC simply-supported and continuous beams subjected to fire in 186 cases. In the analysis, K, section dimensions and the thickness of concrete cover are regarded as independent variables and some calculation parameters determined by trial and error based on test resuits. Calculation formula for fire endurance of UPC simply-supported and continuous slabs was proposed, and the recommended thicknesses of cover of PC beams and slabs was presented in consideration of the influence of K and section dimensions as well as fire endurance requirements. Comparison analysis of relevant design criterions in China and other countries was performed to verify the rationale of the proposed values.