Regional Conference in Civil Engineering (RCCE) 261 The Third International Conference on Civil Engineering Research (ICCER) August 1 st -2 nd 2017, Surabaya – Indonesia Consolidation Coefficient in Horizontal Direction (C h ) Determined from Field Settlement Data By Using Terzaghi, Asaoka, and Finite Element Methods Case Study: Reclamation for Container Yard at Kuala Tanjung, Medan, North Sumatera Yudhi Lastiasih 1 , Noor Endah Mochtar 2 , Farah Nasya 3 1 Lecturer of Civil Engineering, FTSP, Institut Teknologi Sepuluh Nopember, Surabaya, Indonesia. 2 Professor of Civil Engineering, FTSP, Institut Teknologi Sepuluh Nopember, Surabaya, Indonesia. 3 Undergraduate Student of Civil Engineering, FTSP, Institut Teknologi Sepuluh Nopember, Surabaya, Indonesia * Corresponding author: yudhi.lastiasih@gmail.com, noormochtar@gmail.com Abstract - In order to predict the consolidation period in the field, consolidation coefficient in vertical direction (C v ) parameter is needed. When vertical drains installed in the compressible layer in order to shortened the consolidation period, it needs consolidation coefficient in horizontal direction (C h ). This C h parameter has to be determined from the field settlement that usually obtained from the trial embankment. However, it is very expensive to carry out the trial embankment; therefore, it is usually assumed to be 2 till 5xC v . In this paper, the assumption of the C h value will be proven by using field settlement data taken from the trial embankment at the reclamation area for container yard at Kuala Tanjung, Medan, By choosing the C h value, the compression vs time curves were predicted by adopting the Terzaghi, Asaoka, and Finite Element methods. Afterwards, these predicted settlement curves were plotted with the field settlement curves; from this plotting, it could be figured out the predicted curves which has C h value the same with the field C h value. The results show that from three methods adopted in this study, only the Terzaghi and the Asaoka methods give satisfactory results in settlement prediction. Consequently, only the Terzaghi and Asaoka methods are adopted to determine the C h value. The C h value obtained is about the same, that is 3C v until 5C v . When that C h value used back to predict the settlement, the Asaoka method gives better result than the Terzaghi method. Keywords Asaoka method, consolidation coefficient C h , finite element method, Terzaghi method, trial embankment I. INTRODUCTION Consolidation settlement is a common problem found when embankment is built on very soft to soft clay soil. It takes place in very long period of time due to permeability coefficient of the clay soil is very small. Therefore, method to accelerate the consolidation process has been developed. One of the common method is preloading combined with vertical drain. The common material used for vertical drain is prefabricated vertical drain (PVD). By installing the PVD, the excess pore water pressure will flow out in vertical and horizontal directions. For this purpose, it needs coefficient consolidation in vertical direction (C v ) and horizontal direction (C h ). The value of C h has to be determined from the field settlement that is usually obtained from the trial embankment. However, it is very expensive to carry out the trial embankment; therefore, it is usually assumed to be 2xC v until 5xC v . In this paper, the C h value will be determined from settlement field data taken from the trial embankment at the reclamation area for container yard at Kuala Tanjung, Medan, North Sumatera. The methods adopted to determine the C h value were Terzaghi [1], Asaoka [2], and Finite Element [3] methods. From this study, it will be known the exact value of C h and the best method to determine it. II. TERZAGHI, ASAOKA, AND FINITE ELEMENT METHODS A. Terzaghi Method Terzaghi formula to predict the consolidation settlement in the field has been popularly known since 1925. The existing formula has to be slightly modified if the embankment placed step by step. If load placed each step is Δp, the effective overburden stress is p o ’, and the pre consolidation stress is p c ’ (as shown in Figure 1) the consolidation formula [4] is 1. For [p’ o + Δp 1 ] ≤ p c ’                   o p p o p H e Cs Sc ' ' log 1 1 0 (1) 2. For [p’ o + Δp 1 + Δp 2 ] > p c ’ (see Figure 1)                   c c c p p p p H e C p p p H e Cs Sc ' ' log 1 ' ' log 1 2 1 0 0 1 0 0 (2) 3. For [p’ o + Δp 1 + Δp 2 + Δp 3 ] > p c ’ (see Figure 1)