以少量水泥改良軟弱粘土壓密性質之研究

A Study on Using Small Quantity of Cement to Improve the Consolidation Properties of Soft Clays

李永欽(Yung-Chin Lee)

指導教授 ： 馮道偉

中原大學/工學院/土木工程研究所/碩士(2003年)

https://doi.org/10.6840/cycu200300148

摘要

摘 要
近年來，台灣人口的增長，使得土地的利用已經到達了飽和狀態，致使不得不選擇在高含水量的軟弱地盤上構築結構物，為了使軟弱地盤穩固需進行地盤改良，而以水泥深層攪拌工法為常用且成效頗佳之地盤改良工法，國內外都有相當多的案例。文獻中有關於土壤-水泥的性質多止於強度，甚少見到壓密性質的資料。
本研究以石門水庫淤泥、高嶺土及關渡薄管土樣進行基本物理性質試驗、X-Ray分析及CMO試驗，再以低水泥配比製成全部拌合及局部半高拌合試體，進行單向度壓密試驗與無圍壓縮試驗，來研究現地土層全部改良及半高複合土柱改良的壓密性質。
試驗結果顯示：(1)土壤-水泥之預壓密應力會隨水泥含量及養治時間之增加而增加；(2) 土壤-水泥之Cα/Cc與原狀土之Cα/Cc比較有下降的現象，全部拌合之Cα/Cc約原狀土0.4倍、局部拌合之Cα/Cc約原狀土0.7倍；(3)全部拌合方面，水泥含量越高則Cα/Cc越高，局部半高拌合方面，水泥含量越高則Cα/Cc越低；(4) 在壓密係數方面，cv會隨水泥配比量、養治時間及壓密應力之增加而降低，在高壓密應力下會降低至約原狀土0.8倍； (5)在預壓密應力方面，三柱半高改良較單柱半高改良為佳；(6)在滲透係數方面，土壤-水泥之滲透性隨水泥含量的增加而降低，在σ’v<σ’p 情況下，平均kv約原狀土0.6倍；在σ’v>σ’p 情況下，平均kv約原狀土0.7倍；(7) 利用全部拌合沉陷量來估算局部拌合沉陷量(σ’v<σ’p)，有良好的一致性，平均估算沉陷量S(calculate)為量測沉陷量S(measure)之0.8倍。

關鍵字

壓密 ； 地盤改良 ； 局部半高拌合 ； 水泥深層攪拌工法

並列摘要

Abstract
In recent years, the fast growing of population in Taiwan causes saturated occupancy of the land so that buildings have been constructed on soft soils. In order to stabilize the soft soil, it is necessary to improve properties of the soft soil. Cement deep mixing method is the most prevalent and useful technique which can be seen both in Taiwan and in other countries. However, most of soil-cement studies only focus on its strength; little study has devoted on the consolidation properties.
In this study, the consolidation properties of soil-cement are investigated by using SHI-MEN Reservoir mud, Kaolinite, and KUAN-TU soil samples. Firstly, the basic physi-property test, X-ray diffraction analysis, and CMO test were conducted on the samples. Secondly, the specimens of soil-cement whole mixing and partial mixing of low cement content were made and tested in one-dimensional consolidation and unconfined compression conditions.
The results of this study show (1) the preconsolidation pressure increases with the increasing amount of the cement content and curing time. (2) Cα/Cc of soil-cement whole mixing is 0.4 times the Cα/Cc of original soil; Cα/Cc of soil-cement partial mixing is 0.7 times of the Cα/Cc of original soil. (3) in soil-cement whole mixing, higher content of cement causes higher Cα/Cc, but in soil-cement partial mixing, higher content of cement causes lower Cα/Cc. (4) cv decreases with the increasing cement content, curing time and consolidation pressure. Under high consolidation pressure, cv decreases to 0.8 times cv of the original soil. (5) the preconsodilation pressure of three columns of semi-high improvement is higher than one column semi-high improvement. (6) the permeability of soil-cement decreases with the increasing cement content. For example, whenσ’v<σ’p, the average kv was about 0.6 times the kv of the original soil; when σ’v>σ’p , the average kv was about 0.7 times the kv of the original soil. (7) in making use of thel soil –cement whole mixing data to calculate the settlement of soil-cement partial mixing forσ’v<σ’p , good agreement is obtained.The average settlement calculated was about 0.8 times of the measured average settlement.

並列關鍵字

Cement deep mixing method ； partial mixing ； consolidation ； stabilize the soft soil

參考文獻

1.張惠文、張吉佐、洪明瑞、張崇義 (2000)，「台灣地區地盤改良技術之應用現況」，地工技術雜誌，第78期，第5-18頁。

20.李嘉益 (2001)，”水泥系複合土壓密性質之研究”，私立中原大學土木工程學系碩士論文。

10.Newman, A. C. D. (1987), “Chemistry of Clays and Clay Minerals”, Mineralogical Society, John Wiley & Sons New York.

15.Ingles, O. G. (1970)," Mechanisms of Clay Stabilization with Inorganic Acids and Alkalis.", AUST, Journal Soil Research,Vol.8,pp,581-596 .

16.Kawasaki, T. (1981).”Deep Mixing Method Using Cement Hardening Agent ”, Proceeding of 10th ICSMFE ,Stokeholm,pp.721-724.