Down slope soil erosion usually happens when there is displacement of soil by the agents of wind, water or others. The soil is being washed away and gives the ill-effect to buildings, structures or other livings in the surrounding. Soil nailing which can be categorised as reinforced soil walls can prevent the down slope soil erosion. Soil nailing is one of slope stabilisation techniques in soil by installing “nails” into a slope or excavation as construction proceeds from “top down”. Soil nailing has developed as a means of providing temporary support during construction, as permanent retaining structures and walls and also as slope repairs. The technique has been proved to be very cost-effective in suitable conditions, both for new excavations and for the stabilisation of slopes which are becoming unstable with time (Milligan, 1997).
Soil nailing is commonly used in Malaysia’s slopes as slope stabilisation work. The slopes repaired by the soil nailing are basically in short distance but it is strong enough to hold the slopes from collapse to the ground and affected buildings, structures, roads and people. According to Chow (2006), the popularity of soil nail slope is due to its technical suitability as an effective slope stabilisation method, ease of construction and relatively maintenance free. Tan (2004) had added that soil nailing is therefore, commonly adopted for slope remedial and stabilisation works as it can be carried out on the slope surface with minimum earthworks and therefore lower risk during construction.
Malaysia roadsides are mostly consisting of slopes. The slopes are easily failed and could harm the road users as it collapse due to water effect after rainy day. This situation had made the designers to come out the design to construct slope stabilisation works such as soil nailing to retain the slopes from fall. Design of soil nailing that need to be installed into the slopes must be suitable and strong enough to prevent any failure modes happen. If not, it can cause damage to roads and structure surrounding. In addition, the construction of soil nailing is no more economical and cost-effective if designers and contractors had wrongly installed the structure.
Nowadays, the application of soil nailing in Malaysia has been increasingly used to stabilise slopes and soils. It is because the technique is cost effective and very suitable for Malaysian slopes that are distressed, steep or high with unsatisfactory factor and safety. However, improper technique of installation of soil nailing can cause several failures and unsatisfactory performance. Both engineer and contractor should take seriously in designing and constructing the soil nailing. The design should be suitable enough to the soil and the cost factor also need to be considered according to the design. The components and materials selection for the design also important to ensure the soil nailing is suitable with the places and cost. Hence, the research is conducted to identify the design that commonly used, particularly the selection of “nails” type and its considerations. Besides, the most suitable design of soil nailing used in roadways also will be determined by the research.
The aim of this research is to study the designs of soil nailing technology used in Malaysia’s roadways including the materials and equipment used, method of construction and of course the cost implication for each design.
In order to achieve the research aim, the research objectives to be carried out are as follows:
a) To identify the designs of soil nailing that commonly used in roadways.
b) To analyse the cost implication of soil nailing.
c) To recommend on the light of the above objectives, the most suitable type of soil nailing to be used in roadways.
1.5SCOPE OF STUDY