振冲碎石桩在粘土地基处理工程中的应用

采用振冲法在地基中设置碎石桩加固地基的振冲碎石桩法是一种很好的地基处理方法 ,具有施工工艺简单、成桩速度快、工程造价低等优点 ,在处理诸如砂土、粉土、粘土、饱和黄土以及人工填上等软土地基中得到了广泛的应用。结合某粘土地基土工程中采用振冲碎石桩的应用情况 ,对振冲碎石桩在粘土地基中的处理效果、施工控制标准、以及存在的问题进行了分析 ,以供今后类似工程应用借鉴     

和安花园振冲碎石置换桩消除砂土液化的经验

通过振冲置换碎石桩在处理液化地基中的工程实践,论述了振冲置换碎石桩法的施工工艺及处理效果,证明用于处理饱和砂土及粉土液化及提高地基上的承载力是可行的。     

应用振冲碎石桩处理洞穴发育的粘性土地基

本文介绍了振冲碎石桩的加固机理,并详细介绍了应用振冲碎石桩处理洞穴发育的粘性土地基的工程实例。实践证明,处理后的地基承载力明显提高,压缩性显著降低,洞穴隐患已经消除,应用振冲碎石桩处理洞穴发育的粘性土地基是经济可行的。     

紫荆·丽江城振冲碎石桩施工技术

结合衢州紫荆.丽江城振冲碎石桩地基处理工程,介绍了振冲碎石桩的施工方法及技术要点;阐述了振冲碎石桩复合地基能提高地基土承载力、增强稳定性、减少沉降与不均匀沉降,且施工简便、快速、节省造价,是一种经济、合理的地基加固方法,具有广泛的经济和社会效益。     

振动沉管砂石桩加固饱和粉土地基的机理研究

文章根据室内外实验资料，阐述了振动沉管砂石桩加固饱和粉土地基的机理，并由此提出了桩间距的确定原则。工程实践表明，振动沉管砂石桩比振冲碎石桩加固地基更具技术与经济效益。     

振冲碎石桩在砂土地基处理中的应用及加固机理

介绍了振冲碎石桩法应用于地基加固处理的施工方法，从地基土的密实度、碎石桩体的排水效应等方面，分析了碎石桩复合地基的抗液化加固机理，提出了振冲碎石桩处理砂土地基的有效性。     

振冲碎石桩复合地基施工要点

振冲碎石桩复合地基适用于处理不排水抗剪强度不小于20kPa的粘性土、粉土、饱和黄土和人工填土等地基。一、施工准备 1.作桩位布置方案并确定间距。对于大面积满堂处理,宜用等边三角形布置;对于独立或者条形基础,宜用正方形、矩形或等腰三角形布置。桩的间距     

西区水厂三期扩建干化场振冲碎石桩施工技术

本文结合福州西区水厂三期扩建干化场振冲碎石桩地基处理工程,阐述振冲碎石桩的施工方法及技术要点:振冲碎石桩复合地基能提高地基土承载力、增强稳定性、减少沉降及不均匀沉降,且施工简便、快捷、节约造价,是一种经济、合理的地基加固方法,具有广泛的社会和经济效益。     

振冲碎石桩处理淤泥质土层适用性试验研究

通过对振冲碎石桩处理前后的淤泥质土层各项物理力学指标对比、单桩静载试验、单桩复合地基静载试验、多桩复合地基静载试验、桩土应力测试以及碎石桩桩体动力触探等各项检测结果深入分析,表明振冲碎石桩对淤泥质类土的处理效果是显而易见的。     

振冲碎石桩技术在地基处理中的应用

某海堤地基存在较厚的饱和粉细砂液化层,采用振冲碎石桩技术进行加固处理。文章详细论述了振冲碎石桩加固此海堤地基的设计、施工及检测,结果表明采用该方法能取得较好的地基加固处理效果。     

碎石桩复合地基的沉降与固结计算以及稳定分析

给出了碎石桩复合地基的沉降计算方法,分析了碎石桩复合地基固结的原因和计算方法,并给出了碎石桩复合地基与复合土体的稳定性验算方法。     

振冲碎石桩在软土挡墙地基处理中的应用

阐述了振冲碎石桩处理软土地基的作用机理和振冲碎石桩设计方法,通过大连某挡墙软土地基加固处理实例,并采用有限元仿真分析计算其沉降变形,证明了振冲碎石桩设计的可行性。     

刚性基础下碎石桩复合地基临塑荷载的确定

为探讨碎石桩复合地基的承载力,从碎石桩的荷载传递和破坏性状出发,建立碎石桩复合地基的计算模型。基于半空间轴对称弹性理论及基本假定,考虑散体材料桩在荷载传递过程中的径向膨胀变形,根据桩土变形协调及桩土界面上径向应力平衡条件,得到桩土应力比的表达式。应用莫尔-库仑破坏准则,给出了碎石桩复合地基临塑荷载和临界荷载的计算公式。最后,与碎石桩复合地基极限承载力经典方法的计算结果进行对比,结果表明,计算所得的临界荷载十分接近。     

Experimental study on the load bearing behavior of geosynthetic reinforced soil bridge abutments on yielding foundation

This paper presents an experimental study of the load bearing behavior of geosynthetic reinforced soil (GRS) bridge abutments constructed on yielding clay foundation. The effects of two different ground improvement methods for the yielding clay foundation, including reinforced soil foundation and stone column foundation, were evaluated. The clay foundation was prepared using kaolin and consolidated to reach desired shear strength. The 1/5-scale GRS abutment models with a height of 0.8 m were constructed using sand backfill, geogrid reinforcement, and modular block facing. For the GRS abutments on three different yielding foundations, the reinforced soil zone had relatively uniform settlement and behaved like a composite due to the higher stiffness than the foundation layers. The wall facing moved outward with significant movements near the bottom of facing, and the foundation soil in front of facing showed obvious uplifting movements. The vertical stresses transferred from the footing load within the GRS abutment and on the foundation soil are higher for stiffer foundation. The improvement of foundation soil using geosynthetic reinforced soil and stone columns could reduce the deformations of GRS abutments on yielding foundation. Results from this study provide insights on the practical applications of GRS abutments on yielding foundation.     

Geosynthetic-encased stone columns: Numerical evaluation

Stone columns (or granular piles) are increasingly being used for ground improvement, particularly for flexible structures such as road embankments, oil storage tanks, etc. When the stone columns are installed in extremely soft soils, the lateral confinement offered by the surrounding soil may not be adequate to form the stone column. Consequently, the stone columns installed in such soils will not be able to develop the required load-bearing capacity. In such soils, the required lateral confinement can be induced by encasing the stone columns with a suitable geosynthetic. The encasement, besides increasing the strength and stiffness of the stone column, prevents the lateral squeezing of stones when the column is installed even in extremely soft soils, thus enabling quicker and more economical installation. This paper investigates the qualitative and quantitative improvement in load capacity of the stone column by encasement through a comprehensive parametric study using the finite element analysis. It is found from the analyses that the encased stone columns have much higher load carrying capacities and undergo lesser compressions and lesser lateral bulging as compared to conventional stone columns. The results have shown that the lateral confining stresses developed in the stone columns are higher with encasement. The encasement at the top portion of the stone column up to twice the diameter of the column is found to be adequate in improving its load carrying capacity. As the stiffness of the encasement increases, the lateral stresses transferred to the surrounding soil are found to decrease. This phenomenon makes the load capacity of encased columns less dependent on the strength of the surrounding soil as compared to the ordinary stone columns.     

筋箍长度及刚度对加筋碎石桩复合地基承载力影响分析

针对加筋碎石桩复合地基中桩体性能,通过有限元数值模拟与模型试验对比分析,验证了数值模型的可靠性,进而变换加筋长度,研究分析了复合基础下端承加筋单桩与群桩的极限承载能力和破坏模式。研究结果表明:筋材强度较低时,加筋长度不会对桩体破坏模式产生影响,对极限承载能力提高有限;随着筋材强度不断提高,碎石桩在加筋体以下区域发生剪切破坏,并且随着加筋长度的增加向更深土层发展,基础的极限承载能力线性增长。加筋长度对群桩复合地基不同位置处桩体的破坏模式影响不同。相较于边桩,中心桩在桩身较深位置处发生剪切破坏,筋材需达到较深的长度才发挥约束效果。     

流塑淤泥地层中大型泵房的沉井施工

在流塑淤泥地层中进行泵房的沉井施工,容易产生突沉、偏移、反涌、超沉不止及施工过程难以控制等问题。扬州第五水厂取水泵房的沉井施工采用振冲碎石桩处理地基,不仅降低了地基的淤泥液化指数,而且碎石桩对沉井下沉也起到了支撑和导向作用。该施工方案的成功应用表明,在相似土层中通过改变碎石桩的长度、直径、桩距等手段调整地基承载力,使沉井在淤泥中的下沉过程成为一个可控工艺,具有施工简单、成本低的优点。     

振冲碎石桩处理深厚层软土地基

笔者结合工程实例 ,说明了振冲碎石桩处理深厚层软土地基 ,能提高地基承载力 ,减少基础工程投资     

Modeling of uniformly loaded circular raft resting on stone column-improved ground

In the present paper, a mechanical model has been developed to study the behavior of uniformly loaded circular raft resting on stone column-improved ground. The axi-symmetric condition was considered in the analysis. The raft was idealized by a circular plate. The soft foundation soil and granular fill were idealized as the spring-dashpot element and the Pasternak shear layer, respectively. The stone columns were modeled as stiff non-linear springs. To perform an axi-symmetric analysis, stone columns are converted into equivalent concentric rings with one stone column at the center. The finite difference method is used to solve the governing differential equations. The effect of different parameters on the behavior of the circular raft over stone column-reinforced ground was also studied. It was observed that the effect of the modular ratio on the rate of decrease of vertical settlement, radial and tangential moment and the rate of increase of shear force reduces sharply above the value of 40. The shear force developed at the edge of the stone column was critical when the spacing to diameter ratio was around 2.5.