Suffusion and global backward erosion are two of the main internal erosion processes in earth structures and their foundations which may increase their failure risk. For other processes of internal erosion, different classifications exist in order to evaluate the soil erodibility, whereas in the case of suffusion and global backward erosion, no susceptibility classification is available. The absence of suffusion susceptibility classification may be due to the complexity of this process, which appears as the result of the coupled processes: detachment -transport -filtration of a part of the finest fraction within the porous network. Twelve soils, covering a large range of erodibility are tested with a specific triaxial erodimeter. Different criteria based on particle size distribution are compared in order to identify the potential susceptibility to suffusion. For the susceptibility characterization, a new energy based method is proposed. This method can be used for cohesionless soils and clayey sand and a single classification is obtained for suffusion tests realized under flow-rate controlled conditions or by increasing the applied hydraulic gradient. For several tests performed on a mixture of kaolinite and sand, suffusion of clay is accompanied by a global backward erosion process. Characterization of the development of clayey sand backward erosion is also addressed by this method. Finally a complete methodology is detailed for the suffusion and global backward erosion susceptibility characterization.

Suffusion is a selective erosion of fine particles under the effect of seepage flow within the matrix of coarser particles. This complex phenomenon appears as a combination of three processes: detachment, transport and possible filtration of finer fraction. It can induce a change in particle size distribution, porosity and hydraulic conductivity of the material. With the objective to characterize the suffusion susceptibility, downward seepage flow tests were conducted. Four different cohesionless soils were tested under hydraulic gradient controlled conditions or under flow rate controlled conditions. This study shows the significant effect of hydraulic loading history on the value of critical hydraulic gradient.Moreover, method characterizing the erosion susceptibility based on rate of erosion does not lead to a unique characterization of suffusion process for different types of hydraulic loading. The new analysis is based on energy expended by the seepage flow and the cumulative eroded dry mass. The results demonstrate that this approach is more effective to characterize suffusion susceptibility for cohesionless soils.

Internal erosion is one of the main causes of instabilities within hydraulic earth structures. Four internal erosion processes can be distinguished, and this study deals with the process of suffusion, which corresponds to the coupled processes of detachment–transport–filtration of the soil’s fine fraction between the coarse fraction. Because of the great length of earth structures and the heterogeneities of soils, it is very difficult to characterize the suffusion susceptibility of the different soils. Nevertheless, a statistical analysis can be performed to optimize the experimental campaign. By using a dedicated erodimeter, an experimental program was set up to study suffusion susceptibility of 31 specimens of nonplastic and low-plasticity soils. The suffusion susceptibility is determined by the erosion resistance index, which relates the total loss of mass with the total energy expended by the seepage flow. Fourteen physical parameters are selected, and a multi-variate statistical analysis leads to a correlation between the erosion resistance index and all these parameters. A statistical analysis is performed to identify the main parameters and to focus on those that can easily be measured on existing structures. By distinguishing gap-graded and widely graded soils, two correlations are proposed to estimate the erosion resistance index.

The main problem of road construction on saturated soft soils is due to their low bearing capacity and large settlement. One of the solutions to such problems is to install piled box culverts-geofoam. In this study, the pile box culvert-geofoam was modelled as raft foundation. This experimental study was conducted by making a prototype raft file foundation gradually loaded with a maximum vertical load of 20 kN. Different thicknesses of geofoam were utilized in order to observe the influence of thickness on the settlement. Furthermore, difference in settlement is also found when the culvert was constructed with and without geofoam. Thicker geofoam was observed to result in smaller settlement.

Bamboo can be used in construction planning because based on its properties, the mechanical strength of bamboo has high tensile strength and high compressive strength so that it can be used for soil reinforcement. Bamboo which has good quality will also have good mechanical properties as well because bamboo which has good compressive strength, laboratory results also show that bamboo has good tensile strength as well. Thus, there is a correlation between compressive strength and tensile strength in bamboo which is an environmentally friendly material as a soil strengthening material. The data in this study were using bamboo Apus and Javanese bamboo. Because bamboo is often used in industry and is easily available in Semarang. This study uses a simple linear method (Ordinary Least Squares). Simple linear regression model is one of the regression models that are often used in regression analysis. The dataset divided into 2 part, namely by comparing 60% of training data and 40% of testing data. The result from the data testing showing linier regression (least squares) estimate becomes very sensitive to random errors in the observed target, producing a large variance and the following results are obtained Correlation Coefficient 0.99607873, Mean Squared Error 12. 58799, Variance Score 125.60. The results show that the correlation coefficient is 0.99607873, it’s mean that the linear model is close to number 1 meaning that this model is a good model because the correlation coefficient value is close to 1 so there is a positive relationship between or positive correlation between the compressive and tensile tests.

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Bamboo is an environmentally friendly material. Many benefits of bamboo that we can get. Indonesia as a bamboo-producing country needs easy techniques to make good classification of bamboo. Bamboo is composed of fibers and fiber adhesives. There are various kinds of bamboo in Indonesia. This study uses digital image processing with fuzzy c means based segmentation to identify bamboo. Segmentation is an important thing in image processing. By using fuzzy c means in segmentation in this study obtained good segmentation results. This study uses 4 types of bamboo, namely Javanese bamboo, Ori bamboo and Petung bamboo and Wulung bamboo. There are 40 images as training images and 12 test images. The results of segmentation show that fuzzy c means produces good segmentation with the number of iterations between 20-23 and time ranging from 0.11 to 0.15. The accuracy of this test reaches 80%.

The existence of soft soil is one of the obstacles in building road infrastructure, where the carrying capacity of soft soil is very low and can create instability of a building above it, and this is still one of the serious problems that must be overcome. One solution to building a road over soft soil is by using the pavement with a glued plate system, this model is considered to be stronger when compared to the conventional [1] slab pavement system because the addition of piles as pavement anchor can increase the stability of the pavement because it can increase the bearing capacity of the pavement plate.This research was carried out by an experimental test in the laboratory by making a prototype of slab pavement supported by piles. Applied lateral load is 1 kN, 2 kN and 4 kN from modification vibrator machine. Other than the experimental test, in addition, finite element method analysis carried out, and compared the results of the experimental test.The experimental results showed that an increase in lateral loading would increase the deflection of the slab pavement, for a lateral load of 1 kN there was a deflection of 0.21 mm and an increase of 34% for loading of 2 kN and an increase of 45% for loading 4 kN. The pattern is the same in the finite element method analysis, where there was a 9.3% increase for 2 kN loading and increased to 34% for 4 kN loading.