第9单元_碎石桩.pptVIP

第9章 碎石桩Chapter 9 Stone Column 9.1 概 论9.1 Introduction 在地基中设置由碎石组成的竖向增强体（或称桩体）形成复合地基达到地基处理的目的，均称为碎石桩法。 按施工方法的不同，可分为（1）振冲碎石桩法；（2）干振挤密碎石桩法；（3）沉管碎石桩法；（4）沉管夯扩碎石桩法；（5）袋装碎石桩法；（6）强夯置换碎石桩法。 振冲碎石地基处理 夯扩碎石桩 碎石振冲置换桩 碎石桩地基处理 9.2 振冲碎石桩法9.2 Vibroflotation Stone Column Method 采用振冲法在地基中设置碎石桩加固地基的方法称为振冲碎石桩法。振冲碎石桩法适用于处理不排水抗剪强度不小于20kPa的黏土、粉土、砂土、饱和黄土和人工填土地基。 9.1.1 Introduction For over 70 years depths vibrators have been used to improved the bearing capacity and settlement characteristics of weak soils. Vibro compaction was introduced and developed to maturity by the Johann Keller Company in 1936, which enabled the compaction of non-cohesive soils to be formed with excellent results. Vibro compaction has been applied successfully on numerous sites around the world. Reliable stone column production by vibro compaction in cohesive soils with a high water content is achievable with the aid of a heavy water jet. Water is jetted from the vibrator tip as the vibrator is lowered to the desired depth. Mud flushes loosened soil and rises to the surface, stabilising the cavity. This is known as the wet vibro replacement method. To overcome the limitations of the vibro compaction method, a technique to insert the vibrator into the soil without the aid of simultaneously flushing in water was developed in 1956. After the vibrator is lifted, the temporarily stable cylindrical cavity is filled with coarse material, section by section. The coarse material is then compacted by repetitive use of the vibrator. This vibro replacement procedure came to be known as the conventional dry method. Such technical developments in dense stone column construction allowed for a greater range of treatable weak natural soils and man-made fills. Vibro replacement continues to be widely used in Europe to improve weak soil. It has a reputation for providing stable ground which allows for safe and economic construction of residential and light commercial and in