Sains Malaysiana 46(11)(2017): 2029-2034

http://dx.doi.org/10.17576/jsm-2017-4611-02

Experimental Identification on Thresholds for early warning of Rainfall-induced Failure on Fractured Slopes after Giant Earthquake

(Pengecaman Eksperimen Ambang untuk Amaran Awal Kegagalan Aruhan Hujan ke atas Cerun Retak selepas Gempa Bumi Besar)

ZONG-JI YANG^1*, JIAN-PING QIAO¹, DONG HUANG¹, TARO UCHIMURA² & LIN WANG³

¹Key Laboratory of Mountain hazards and Surface Process, Institute of Mountain hazards and Environment, Chinese Academy of Science, Chengdu 610041, China

²Department of Civil Engineering, Saitama University, Saitama, Japan

³Chuo Kaihatsu Corporation, Tokyo

Diserahkan: 26 Januari 2017/Diterima: 4 Jun 2017  

ABSTRACT

Prevention and mitigation of rainfall induced geological hazards after the Ms=8 Wenchuan earthquake on May 12th, 2008 were significant for rebuild of earthquake hit regions. After the Wenchuan earthquake, there were tens of thousands of fractured slopes which were broken and loosened by the ground shaking, they were very susceptible to heavy rainfall and change forms into potential debris flows. In order to carry out this disaster reduction and prediction effectively in Longmenshan region, careful real-time monitoring and pre-warning of mountain hazards in both regional and site-specific scales is reasonable as alternatives in Wenchuan earthquake regions. For pre-warning the failure of fractured slopes induced by rainfall, the threshold value or the critical value of the precipitation of hazards should be proposed. However, the identification of critical criterion and parameters to pre-warning is the most difficult issue in mountainous hazards monitoring and pre-warning system especially in the elusive and massive fractured slopes widespread in Wenchuan earthquake regions. In this study, a natural coseismic fractured landslide in the Taziping village, Hongkou County, Dujianyan City, was selected to conduct the field experimental test, in order to identify the threshold parameters and critical criterion of the fractured slopes of Taziping. After the field experimental test, the correlation of rainfall intensity, rainfall duration and accumulative rainfall was investigated. The field experimental test was capable of identifying the threshold factors for failure of rainfall-induced fractured slopes after the giant earthquake.

Keywords: Fractured slopes; giant earthquake; rainfall induced; threshold factors

ABSTRAK

Pencegahan dan mitigasi bencana geologi aruhan hujan selepas gempa bumi Ms = 8 di Wenchuan pada 12 Mei 2008 adalah penting untuk membina semula kawasan-kawasan yang terjejas. Selepas gempa bumi ini, terdapat ribuan cerun yang retak dan pecah kerana gegaran tanah telah terdedah kepada hujan lebat, berpotensi berubah menjadi aliran puing. Pengurangan serta ramalan bencana secara berkesan di rantau Longmenshan dapat dicapai dengan pemantauan masa nyata dan pra-amaran terhadap bencana gunung pada wilayah dan tapak skala spesifik. Bagi pra-amaran untuk kegagalan cerun retak aruhan hujan, nilai ambang atau kritikal bencana perlu dicadangkan. Walaubagaimanapun, pengenalpastian kriteria kritikal dan parameter untuk pra-amaran adalah isu yang paling sukar dalam pemantauan bancana pergunungan. Malahan sistem pra-amaran terutama di cerun yang retak sukar difahami serta meluas di kawasan gempa Wenchuan. Dalam kajian ini, tanah runtuh koseismos semula jadi di kampung Taziping, Wilayah Hongkou, Bandar Dujianyan, telah dipilih untuk ujian eksperimen lapangan. Hal ini bagi mengenal pasti parameter ambang dan kritikal pada cerun pecah Taziping. Selepas ujian eksperimen lapangan, hubung kait antara kekerapan dan tempoh hujan diselidiki. Ujian uji kaji lapangan ini mampu mengenal pasti faktor ambang untuk kegagalan cerun retak aruhan hujan selepas gempa bumi gergasi.

Kata kunci: Aruhan hujan; cerun retak; faktor ambang; gempa bumi besar

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*Corresponding author; email: yzj@imde.ac.cn