GEOLOGICAL INFLUENCE TO THE CAUSES OF MASS MOVEMENT AT PASIR HONJE (KM 92+200 – KM 92+800) DESA CIBODAS , KECAMATAN SUKATANI, KABUPATEN PURWAKARTA,

PROCEEDINGS JOINT CONVENTION BALI 2007
The 32nd HAGI, The 36th IAGI, and The 29th IATMI Annual Conference and Exhibition

GEOLOGICAL INFLUENCE TO THE CAUSES OF MASS MOVEMENT AT PASIR
HONJE (KM 92+200 – KM 92+800) DESA CIBODAS , KECAMATAN SUKATANI,
KABUPATEN PURWAKARTA, PROVINCE OF WEST JAVA

Wahyuni Tri Sundari
Geological Engineering Department, Faculty of Engineering, Gadjah Mada University

ABSTRACT
Lack of research about geological condition and characteristic of rock and soil in technical construction may cause to the damage even failed of construction. Such as happen at Pasir Honje (Km 92+200 – Km 92+800) Desa Cibodas, Kecamatan Sukatani, Kabupaten Purwakarta Province of West Java where part of Cipularang toll road. This road was damage by landslide. It was happen at point Km 92+350, Km 92+450, Km 92+650 and Km 92+800. Mapping of Geomorphology, geology, drainage, land uses and mass movement spreading was needed to analyze controlling factor, causes and movement of rock and soil mechanism.
Main controlling factor of mass movement at the research area was geological factor, morphology also slope of hydrology. The main cause was slope water infiltration and overburden that was result from access of Cipularang toll road construction. Both of controlling factor and causes factor was interacted and makes mass movement at the research area. Mass movement type at the research area was landslide with dimension of width until 800 m which controlled by Pasir Munjul fault also lithology contact of tuffaceous sandstone-volcanic breccia member of Qos and claystone-silt member of Jatiluhur Formation (Mdm). Beside that other landslide with smaller dimension was happen. It was debris slump (Km 92+350) and debris slide (Km 92+450, Km 92+650 dan Km 92+800). This landslide was controlled by contact of lithology between colluvial deposits (which result from the biggest landslide) and claystone – silt (Jatiluhur Formation) which jointed also overburden from activities of Cipularang toll road.
To handle this landslide retaining building such as shoe shape and bore piled was made and installed deeper than sliding plane. The shoe shape was made along Km 92+350 – Km 92+450, while the bore piled was made along Km 92+650 – Km 92+800. Seeking from the geological condition of Pasir Honje which exists of pasir munjul fault and the toll road lies on colluvial deposit so the Cipularang toll road at Pasir Munjul (point of Km 92+200-Km 92+800) need to be reviewed.