Study of Control Well to Prevent Landslides Risk During Construction of Cisumdawu Toll Road

Abstract

Landslides often occur in the Cisumdawu toll road area. The reason is that the toll road section is located in a basin surrounded by three volcanic mountains, namely Mount Tampomas, Manglayang, and Patuha, so that it has geographical conditions in the form of ravines and cliffs that have steep slopes. The purpose of this research is to study the control well planning as a short term/temporary solution (during the construction period of 3-5 years) that can be carried out in the construction of the Cisumdawu Toll Road project section 1 phase 3 at STA 0+975 in order to be safe from hydrological disasters which are expected to modeled on other toll road construction projects in need. The research phase begins with the primary data collection phase through soil sampling, soil laboratory testing, and documentation of existing conditions. Secondary data in the form of rainfall data, contour maps, postal maps of rainfall, and drilling log data. Furthermore, the data processing stage begins with geotechnical analysis in the form of taking soil samples which are then tested in the laboratory, as well as slope stability analysis using the finite element method, namely Plaxis 2D software in three conditions, namely before excavation, after excavation without load and after excavation with traffic loads to determine groundwater level at safe conditions (SF > 1.25). The second stage is a hydrological analysis to calculate the intensity of rainfall with a return period, calculate the infiltration discharge and end with the planning of control wells. Control wells are planned to keep the groundwater level from exceeding the critical water level, which can cause landslides. From the research, the planned control well has a diameter of 1 m which is dug as deep as 10 m, with the choice of a centrifugal pump which has a diameter of 12 inches, a total head of 10 m, and a discharge of 14 m 3 / min and equipped Water Level Control (WLC) as sensors.