王勤福

摘　要：石灰、粉煤灰穩(wěn)定土被廣泛應用于高速公路底基層，它不僅具有經(jīng)濟和環(huán)保意義，還具有較高的后期強度和較好的水穩(wěn)定性.用于此種穩(wěn)定土的土類以粘土或亞粘土為最佳，其塑性指數(shù)最好在12～20之間，但公路工程的特點決定了使用土類的多樣性.淮陰―江都高速公路淮陰段沿線土類多為粉砂土，其液限一般在30%～35%，塑性指數(shù)為8～12，小于0.002　mm的粘粒含量少、活性低、粘聚性差，僅用石灰、粉煤灰來進行綜合穩(wěn)定，早期強度較低，成型質量較差，難以完全達到規(guī)定的強度和穩(wěn)定性要求，這就要求采取一定的技術措施來加以改善.用適量水泥、石灰、粉煤灰進行綜合穩(wěn)定就是針對粉砂土的不利因素提出的一種有效措施.文中通過不同的材料組成比例與強度的對應關系，淺析了摻入水泥前后混合料強度形成機理各自的特點，再現(xiàn)了石灰、粉煤灰穩(wěn)定粉砂土時，摻入水泥能明顯提高混合料早期強度及水穩(wěn)定性的結論.除此以外，作者通過施工現(xiàn)場質量的檢測與控制的實踐和探索，提出配合比是穩(wěn)定土質量的關鍵因素，應嚴格掌握控制，并簡單介紹了施工工藝和配合比檢查的方法.

關鍵詞：粉砂土； 底基層； 綜合穩(wěn)定


Comprehensive Stability of Low Limited Liquid Powdered Sand Earth
for the Groundwork Layer of Expressway

WANG Qin-fu
(Changzhou Communication Construction Supervision Consultation Limited Company,Changzhou,Jiangsu 213002,China)

Abstract：The stable earth of limestone and fly-ash is widely used for the groundwork layer of expressway. It is advantageous to economy and environment protection as well as higher later strength and better water stability. For this purpose, the clay or mild clay is the best with its plasticity index between 12 to 20. But the features of highway construction determine the varieties of earth to be used. Most of the earth used for the expressway from Huaiyin to Jiangdu is powdered sand earth with a liquid limit of 30%～35% and the plasticity index of 8～12.This kind of powdered sand earth greatly lowers the content of clay granules that are less than 0.002　mm in diameter and of low activity and poor cohesiveness . If only limestone and fly-ash are used to strengthen the comprehensive stability, the early strength is lower and the shaping quality is poorer. It is very difficult to fully meet the requirements of regulated strength and stability, so it is required that certain technical measures be taken to improve the strength and stability. It is just an effective measure to use suitable cement, limestone and fly-ash for comprehensive stability of powdered sand earth. Through the corresponding relationship between different ratios of material composition and strength, the author analyses the mechanism and features of strength forming of the mixed materials before and after the mixing of cement.The result shows that if cement is properly mixed with limestone and fly-ash to stabilize the powdered sand earth, the early strength and water stability of the mixed materials is obviously improved. Besides , through practices of quality inspection and quality control at the jobsite, the author puts forward that the mixing ratio is the key factor that affects the quality of stable earth. Therefore ,the formulating ratio should be under strict control. At the same time, the process of construction and the method of inspection for mixing ratio are briefly introduced.
　　Key words：powdered sand; groundwork layer; comprehensive stability