Floods are a regular phenomenon in Indonesia, particularly in the Bangka Belitung region. Natural elements such as soil conditions and excessive rainfall, as well as non-natural variables such as rubbish, concretization in infiltration zones, development in floodplain areas, and so on, all contribute to flood disasters. Dul Village, Pangkalanbaru District, Central Bangka Regency, was one of the flood-affected areas. To assist the community in overcoming issues, community service activities will be carried out with the long-term goal of establishing a flood response community, with the specific goal of providing flood disaster mitigation education to the community. A flood disaster socialization program and an early warning system for the community are among the methods employed to carry out this program. The outcomes of this program have increased public awareness of the potential and causes of flooding, particularly in Dul Village, as well as the function of the early warning system in mitigating flood-related losses.

Liquefaction is a liquefied soil phenomenon caused by cyclic load or earthquake. One of the soil liquefaction prevention methods is the installation of stone column. The stone column is a column filled with compacted rock fragments. It has 50 cm in diameter and 5 m deep This method is believed to reduce the excess pore water pressure that occurs during an earthquake. The stone column has been applied in many construction projects which located in high potential of liquefaction area. This research aims to know the effectiveness of stone column in reducing the liquefaction potential. This research conducted by using borelog data and soil laboratory test. This research also runs the numerical simulation of soil liquefaction with stone column stabilization. The variations in column spacing (2 m; 1.5 m; and 1 m) and subsurface review point (1 m; 1.5 m; 2 m; and 2.5 m) will be applied by using Quake/W from Geostudio 2012 software. The results show that the liquefaction potential can be reduced with the closer stone column spacing up to 1.5 m. Reduction of pore water pressure and liquefaction potential only occurs in the initial period of the earthquake before reaching the peak of earthquake acceleration.ABSTRAKLikuefaksi merupakan fenomena pencairan tanah akibat adanya beban siklik atau gempa. Salah satu metode penanganan likuefaksi yaitu dengan melakukan instalasi stone column. Stone column merupakan suatu kolom yang diisi oleh fragmen batuan yang dipadatkan. Umumya kolom berukuran diameter 50 cm dan kedalaman hingga 5 m. Metode ini dipercaya dapat mengurangi tekanan air pori yang terjadi pada tanah saat gempa. Penelitian ini bertujuan untuk mengetahui efektifitas stone collumn dalam mengurangi potensi likuefaksi. Penelitian ini dilakukan dengan menggunakan data bor dan uji laboratorium. Simulasi numeris juga dilakukan berupa permodelan tanah dengan stabilisasi stone column. Variasi pada jarak stone solumn (2m; 1,5m; dan 1m) dan titik tinjau (1m; 1,5m; 2m; dan 2,5m) dilakukan dengan menggunakan perangkat lunak Quake/w dari Geostudio 2012. Hasil menunjukkan bahwa potensi likuefaksi dapat berkurang dengan jarak stone column yang semakin dekat hingga 1,5 m. Pengurangan tekanan air pori dan potensi likuefaksi hanya terjadi pada periode awal gempa sebelum mencapai puncak percepatan gempa.

Excavation work is a type of work that is commonly found in many construction projects. In carrying out excavation work, it is necessary to consider stable slope conditions so that landslides do not occur during work. Common ground excavation work found on Bangka Island, especially in the city of Pangkalpinang, is kulong excavation, or sea excavation, as an effort to increase depth elevation. This study aims to determine changes in soil slope stability due to excavation work at a certain depth and slope. The study used field observation data in the form of CPT (Cone Penetration Test), hand drill, and data from laboratory analysis. Data analysis was then carried out using the Slope/W software, which is part of Geostudio 2018, to determine the safety factor for soil slopes using the Bishop and Fellenius method. The value of the safety factor produced by Slope/W determines the level of stability of the soil slope. The slope of the soil varied 15⁰, 30⁰, and 45⁰ and the excavation depth was determined to be 4 m and 8 m. The results showed that the safety factor of the 4 m and 8 m excavation depth in the same slope angle was decreasing about 23.18 % while the safety factor of the 15⁰ and 30⁰ excavation slope in the same depth was decreasing about 31.81%