地基處理各種做法施工工藝錦集.doc

4.軟土地基處理

一、 處理方法與特點
二、 復合地基計算原理
三、 換填法設計
四、 強夯法設計
五、 預壓法設計
六、 水泥土攪拌法設計
七、 托換技術

4.1地基處理方法
4.1.1地基處理的目的
軟土地基處理的目的是利用換填、夯實、擠密、排水、膠結、加筋和熱學等方法對地基土進行加固，用以改良地基土的工程特性，主要包括：
1)提高地基的抗剪切強度
2)降低地基的壓縮性 
3)改善地基的透水特性  一種增加地基土的透水性加快固結，另一種是降低透水性或減少其水壓力（基坑抗?jié)B透）。
4.1.2 地基處理方法分類及應用范圍
軟土地基處理的基本方法主要有置換、夯實、擠密、排水、膠結、加筋、和熱學等方法。
常用地基處理方法的原理、作用及適用范圍如下。
1. 換土墊層法
(1)墊層法  其基本原理是挖除淺層軟弱土或不良土，分層碾壓或夯實土，按回填的材料可分為砂(或砂石)墊層、碎石墊層、粉煤灰墊層、干渣墊層、土(灰土、二灰)墊層等。干渣分為分級干渣、混合干渣和原狀干渣；粉煤灰分為濕排灰和調濕灰。換土墊層法可提高持力層的承載力，減少沉降量；常用機械碾壓、平板振動和重錘夯實進行施工。
該法常用于基坑面積寬大和開挖土方量較大的回填土方工程，一般適用于處理淺層軟弱土層(淤泥質土、松散素填土、雜填土、浜填土以及已完成自重固結的沖填土等)與低洼區(qū)域的填筑。一般處理深度為2～3m。適用于處理淺層非飽和軟弱土層、素填土和雜填土
4. Soft Soil

1, treatment and characteristics
II Principles of Composite Foundation
Third, replacement method design
Fourth, the design of dynamic consolidation
5, preloading Design
6, Design of concrete mixture method
7, Underpinning

4.1 Ground handling
4.1.1 The purpose of foundation treatment
The purpose is to use soft handle replacement, compaction, compaction, drainage, cement, reinforcement and thermal methods such as reinforcement of the foundation soil to improve the engineering properties of soil, including:
1) to improve the shear strength of foundation
2) reduce the compressibility of the foundation
3) to improve the permeability of the foundation that increases the permeability to accelerate the consolidation of foundation soil, and the other is to reduce the permeability, or reducing the water pressure (Pit anti-infiltration).
4.1.2 Classification and Application of ground handling area
Soft handle the basic methods are replacement, tamping, compaction, drainage, cement, reinforced, and thermal and other methods.
The principle of common ground handling, role and scope of application are as follows.
1. Replacement Cushion Method
(1) The basic principle is to cushion method excavation of shallow soft soil or poor soil, compacted or compacted soil layer, according to the backfill material can be divided into sand (or sand) bedding, gravel pads, powder ash cushion, cushion of dry residue, soil (lime, lime) cushion and so on. Divided into grade slag slag, mixed dried sludge and intact dry residue; fly ash into the wet gray ash and humidity. Soil replacement layer can improve the bearing capacity, reduce settlement; common mechanical rolling, vibration and heavy hammer compaction plate for construction.
The method commonly used in the large pit area and a large excavation backfill earthwork earthworks generally applies to dealing with the shallow soft soil (silty soil, loose fill elements, miscellaneous fill, and has completed the creek fill weight consolidation of hydraulic fill, etc.) and filling low-lying areas. Generally deal with a depth of 2 ~ 3m. Applies to the handling of non-saturated soft soil shallow, filling and miscellaneous fill factor
 

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