EFFECTS OF WATER ABSORPTION AND NEUTRALIZATION PROPERTIES OF CRUSHED SHELL ON STABILIZATION OF ACID SULFATE SOILS

本研究包括两类室内试验和实地调查，如下所示：一是实验室试验的目的是阐明与含黄铁矿和源自牡蛎壳的碳酸钙等酸性硫酸盐土接触引起的pH升高引起孔隙水波动机制。实验室试验的第二个目的是澄清酸性硫酸盐土、碎牡蛎壳和稳定剂的混合物的承载力和强度特性。一方面，现场库存中期望的产品是确定上述混合物在暴露条件下的凝固情况并确定其弹性模量。从化学试验、力学实验和现场测量记录中得到的主要结果总结如下：(1)将碳酸钙和熟石灰混合到酸性硫酸盐土壤中，孔隙水的量因水的吸收反应（形成氢氧化铁）、脱水反应（形成氧化铁）和二氧化碳的挥发（碳酸钙的溶解）而变化。(2)硫酸酸土、碎牡蛎壳和稳定剂混合后的无侧限抗压强度和CBR值均大于不加壳块的混合土。因此，将破碎的牡蛎壳混合到酸性硫酸盐土壤中有助于降低稳定剂的添加剂含量。(3)用硫酸酸土、碎牡蛎壳和稳定剂混合制成的截面的冲击加速度测量值表明，随着时间的推移，其承载能力逐渐增加，反分析计算的弹性模量比不加壳片的混合制成的截面大。

This study consists of two kinds of laboratory tests and a field inventory shown in the following :The first purpose of laboratory tests is to elucidate the fluctuation mechanism of pore water caused by rise of pH which the contact with acid sulfate soil including pyrite and calcium carbonate deriving from the oyster shell induces. The second purpose of laboratory tests is to clarify the bearing capacity and strength characteristics of the mixture of acid sulfate soil, crushed oyster shell and stabilizer. On the one hand, the products expected in a field inventory are the ascertaining of a solidification of the above mixture under exposure condition and the finding of its elastic modulus.The principal results obtained from chemical tests, mechanical experiments and measurement records at in situ are summarized as follows :(1)Mixing a calcium carbonate and slaked lime into acid sulfate soil, the amount of pore water varies due to the water absorption reaction with formation of an iron hydroxide, the dehydration reaction with formation of an iron oxide and the volatilization of carbon dioxide with dissolution of a calcium carbonate.(2)The unconfined compressive strength and CBR value of the mixture of acid sulfate soil, crushed oyster shell and stabilizer have become larger than those of the mixture without shell pieces. Therefore, the mixing of a crushed oyster shell into acid sulfate soil contributes to a reduction in additive content of stabilizer.(3)According to the impact acceleration values measured on sections which have been made by using the mixture of acid sulfate soil, crushed oyster shell and stabilizer, those bearing capacities increase gradually with a passage of time, and those elastic moduli calculated by inverse analysis are greater as compared to sections which have been made by using the mixture without shell pieces.