EVALUASI PERGERAKAN TANAH PADA PEMBANGUNAN JALAN TOL SEMARANG – SOLO RUAS SEMARANG – BAWEN, SEKSI – II KM 5+500 SAMPAI 5+800

Abstract

ABSTRACT The development of Semarang-Solo highway Phase I Section II, has got many problems in the implementation of local mass movement. One of them is occur in Semarang-Solo highway Km 5 +500 to 5 +800 at the end of the road hardening activity. This mass movement can cause cracks on the hardned road, group boredpile shifting and cracking in capping beam boredpile group.The research method conducted by engineering geological mapping, interpretation of geoelectrical data, bore log and inclinometer datas. These datas can be analyzed to determine the type of mass movement, the triggering factors,causes of mass movement and than mass movement mechanism that occurs in the research area. Cracks on the Semarang-Solo highway Km 5 +500 to 5 +800 basically occured in landslide zone composed of quarry and colluvial deposit that exist above claystone as sliding plane. Type of the mass movement in the research area is slump with a single rotational movement mechanism. Inclinometer data show as that sliding plane, which can cause landslide, exist on 21-28 m below the surface. The cause and triggering factors of landslide control by stratygraphic, physical properties of material that has not been compacted, surface and subsurface water seepage, the morphology of steep hills with slope 35-45 % (Asdak, 1996), and load deposits on the slopes. Mass movement mechanism is initiated by reduction of overburden pressure on the slope, then triggered by the infiltration of water on the uncompacted slope material until the slope material is saturated, increased pore water pressure and have a reduction in soil shear strength. For solving the landslide problem needs improvement focused on the slopes of the water seepage problem, the physical properties of uncompated materials the quarry load mass as the major factor as well as the trigger of mass movement on the Semarang-Solo highway Km 5+500 to 5+800. Recommended slope improvement use grouting, bored pile, vertical drain well, and diversion of surface water. Keywords : Mass movement of highways, engineering geological mapping, geoelectric, bore logs, inclinometer, landslide geometry