Engineering Characteristics and Reinforcement Approaches of Organic Sandy Soil

Jun Hu,Liang Jia,Juan Du,Hong Wei,Wei Wang

doi:10.1155/2018/7203907

Jun Hu, Liang Jia + Show 3 more

Open Access

https://doi.org/10.1155/2018/7203907

Copy DOI

Abstract

Organic sandy soil is widely distributed throughout Hainan Island. This study aimed at addressing the distribution, composition, and formation of organic sandy soil. The engineering properties of organic sandy soil were examined. The experimental results showed that the coefficient of uniformity and coefficient of curvature were 2.07 and 1.25, respectively. The maximum dry density and optimum water content were 1.723 g/cm3 and 12.23%, respectively. The undrained shear strength of organic sandy soil was around 37.5 kPa. The effective stress parameters c and φ were around 4 kPa and 23°, respectively. The compound tangent-exponential model was adopted for capturing the stress-strain behavior of organic sandy soil. As the unconfined compressive strength of the cement-admixed organic sandy soil was much lower than that of ordinary sand, some innovative ground improvement technologies were proposed for stabilizing organic sandy soil, such as thermal pile, fiber, and steel-, bamboo-, and freezing-cemented soil columns. The main purpose of these technologies is to enhance the bearing capacity of organic sandy soil but reduce the usage of cement, as the latter is not an eco-friendly material.

Highlights

Hainan is a rapidly growing tourism province in China with a very long coastline and plants of bays (Figure 1)
Organic sandy soil is widely spread in this island, and field investigations have revealed that 8 of the 12 selected bays in Hainan Island have organic sandy soil (Haikou, Fengjia Bay, Yingge Bay, and Sanya)
Some studies have been conducted on organic soils [2,3,4], the knowledge of organic sand remains scanty

Summary

Introduction

Hainan is a rapidly growing tourism province in China with a very long coastline and plants of bays (Figure 1). Is study investigated the engineering properties (e.g., strength parameters) of organic sandy soil and proposed some innovative ground improvement techniques for this kind of sand. A quantitative analysis was conducted by the ASTM D2974 [10] to check the organic content in the sand. A solubility analysis was conducted to further check how the organic matters existed in the sands. Organic matters may immerse in the pores or are adsorbed on the surface of the sand owing to the long-term microbial activity and physical or chemical effects. The organic sandy soils were formed through the physical, chemical, and biological reactions between organic matter and minerals of sand particles. To model the formation process of organic sandy soil, an indoor experiment was conducted based on the concept of constant head permeability test (Figure 4). The organic content in the sand was found to decrease with the sampling depth, which was consistent with the results obtained from in situ specimens. is confirmed that the assumption about the formation of organic sandy soil was reasonable

Engineering Properties of Organic Sandy Soil

Findings

Proposed Reinforcement Methods