*Corresponding author: The Challenges in Instrumented Physical Model Studies of Peat Soil Siti Nooraiin Mohd Razali 1* , Ismail Bakar 2 , Adnan Zainorabidin 3 1 Research Student, Fkaas, UTHM, Johor 2, 3 Supervisor, Fkaas, UTHM, Johor 1. Introduction A softness and highly compressible peat soil is widely identified in Malaysia. The area covered by peat deposit is about 3.0 million hectares or 7% of the total area of Malaysia [1]. Peat is highly compressible and permeable during the early stage of loading [2]. The factors that control the compressibility characteristics of peat include the fibre content, natural water content, void ratio, initial permeability, nature and arrangement of soil particles, and inter-particle chemical bonding in some of the soils [3]. The construction over peat presents great challenges in the management of the engineering properties of peat that generally passes high water content (>200%), high compressibility (0.9 to 1.5), high organic content (>75%) low shear strength (5-20kPa) and low bearing capacity (<8kN/m 2 ) [4], large deformation and high magnitude and rates of creep [5]. These unique geotechnical characteristics of peat have led to many problems and the construction become challenging in Malaysia [6] [7]. Bearing capacity of this peat soil is very low and it is affected by the high water table and the presence of woody debris in peat [8]. Different construction methods were used when dealing with peat and organic soil condition. The different depth of peat provided the different methods of construction. For a depth less than 3 m, the removal and replacement method should be used. The depth 3m to 10m require preloading stage construction with vertical and sand drain, lightweight fills and surface mattresses and stone column as a method construction. While for depth more than 10m the suitable method was deep stabilization techniques (i.e. piling, dynamic compaction, etc.). So, it is important to engineers to learn the behaviour of peat soil and to know how to tackle the problems or obstruction that arises during the construction in peat. The study on the effect of the load to the behaviour of peat soil has been conducted in the physical model. The challenges faced will be discussed in this study. 2. Project Details A large box with internal dimensions of 200 cm in length, 50 cm in width and 90 cm in height, with a transparent Perspex plate as wall was used to monitor settlement during the test. Plastic sheets were glued on all the surfaces of the Perspex plates that formed as the model wall, so as to reduce the friction effect between soil and the wall. Gridlines papers were installed on the outer side of the box as an indicator. The layers of sand in peat soil also acted as an indicator. Sand has also been added between peat and water which acts as a filter. The model termed as Plane Strain Study (PSS) model was as illustrated in Fig. 1. The peat sample used was collected from MARDI – Integrated Peat Research Station (MARDI-IPRS), Pontian, Johor. The disturbed sample was taken at less than 0.5 m depth due to the high water table. Large fibre content such as wood in the peat soil was removed and peat that passes the sieve (viz metal mesh with size 25 mm x 8 mm) has been used as a foundation in this study. The test set up consisted of a peat layer resting inside the box with the sand as an indicator. Two types of instruments were selected in identifying the settlements and stresses in peat are displacement transducers (DT) and soil pressure gauges (SPG). These instruments were connected to a data logger UCAM-20PC (USB – 21A Scanner) to collect the data. Abstract: The study of the two dimensional small scale models in peat soil has been done in order to analyze the behaviour of the soil under loading. This study explored the settlement occurred, based on the usage of instrumentations and the indicators in the physical model. The unique characteristic of peat brings a big challenge in this study. This paper presents the challenges faced in the study of behaviour of peat soil – load interaction. It can be identified that the main challenges in this study is the behaviour of peat soil, followed by the challenge during the design stage and during the construction stage. The maintenance stage also needs to be considered because the calibration of instruments was done in this stage. In this paper, findings of sand as a suitable material to identifying the deformation pattern are discussed. Keywords: Challenges, instrumented physical model, peat.