Determining Soil Moisture Content and Material Properties with Dynamic Cone Penetrometer

Juha Latvala,Pauli Kolisoja,Heikki Luomala

doi:10.7250/bjrbe.2020-15.511

Juha Latvala, Pauli Kolisoja + Show 1 more

Open Access

https://doi.org/10.7250/bjrbe.2020-15.511

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Abstract

This study utilised static triaxial and dynamic cone penetration tests to examine the identification of changes in strength in soil materials as a result of an increase in moisture content. The applicability of a light dynamic cone penetrometer device in railway environments was also studied. On a broader scale, the aim was to find an investigation method suited to field locations that identify low-quality or persistently moist materials directly from the structure. The triaxial tests found an apparent increase in shear strength when the water content dropped below 7%. Based on the series of laboratory tests, the dynamic cone penetrometer reacted strongly to material density, but the impact of moisture content was also evident. Furthermore, the results showed that dynamic cone resistance is a reasonably unfeasible metric for assessing the structural quality of materials consisting primarily of sand, due to the number of factors affecting the resistance. In the laboratory tests, the lowest dynamic cone resistances were measured in the material with the highest structural quality.

Highlights

In the future, climate change is predicted to steer the global climate towards extreme phenomena, leading to increasingly frequent floods, heavy rains and, in some locations, extreme drought (Trenberth, 2011)
The results suggest that the maximum shear strength begins to increase when the moisture content of the studied materials is below 7%
The results show similarities with the results of the static triaxial tests, as a moisture content dropping below 7% increases dynamic cone resistance

Summary

Introduction

Climate change is predicted to steer the global climate towards extreme phenomena, leading to increasingly frequent floods, heavy rains and, in some locations, extreme drought (Trenberth, 2011). Increased moisture content is known to deteriorate the functionality of earth structures. As reported by Li & Selig (1995), the combination of cyclic loading, fine-grained soils, and excessive moisture content is a very harmful combination for a railway track. Climate change exposes earth structures to accelerated deterioration. The Finnish Transport Infrastructure Agency and Tampere University have initiated a research project that examines the effect of moisture conditions on the bearing capacity of track earth structures and the possible benefits obtainable by drainage. The suitable in-situ test methods vary depending on soil type. For sandy materials, Selig & Waters (1994) have listed functional methods such as standard penetration test (SPT), cone penetration test (CPT), borehole shear test (BST) and dilatometer test (DMT). One of the easiest and lightest to operate is the dynamic cone penetrometer (DCP)

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