Method of estimating the effective zone induced by rapid impact compaction

This paper proposes a method for estimating the effective zone, including effective depth and effective range of compaction degree, from rapid impact compaction (RIC) on sand layer whose fines content is less than 10%. The proposed method utilizes a string of microelectromechanical system accelerometers to monitor the acceleration at various depths and propagation distances during compaction. To interpret and extract useful information from monitored data, peak-over-threshold (POT) processing and normal distribution function were used to analyze the recorded acceleration. The mean and standard deviation of the threshold peak acceleration were used to evaluate the effective depth and the effective range of compaction degree during RIC compaction. Moreover, spatial contours were used to determine the correlation of the threshold peak acceleration against depth and propagation distance from the RIC impact point. These contours help indicating the distribution of the effect zone after compaction. Lastly, a proposed method is suggested for frequent use in trial tests to quickly determine RIC’s required depth and impact spacing.

Evaluasi Perbaikan Tanah Menggunakan Rapid Impact Compaction pada Tanah Berpotensi Likuefaksi

ABSTRAKRapid Impact Compaction (RIC) merupakan salah satu metode perbaikan tanah secara mekanik untuk tanah granular. Prinsip dasar dari Rapid Impact Compaction yaitu menjatuhkan beban hammer dengan tinggi jatuh yang relatif rendah dengan kecepatan yang tinggi. RIC dapat dijadikan alternatif dalam mitigasi likuefaksi. Beberapa penelitian sebelumnya menyatakan bahwa RIC dapat memperbaiki tanah hingga kedalaman 6 m. Pada penelitian ini, evaluasi efektifitas perbaikan tanah menggunakan RIC dilakukan di lokasi Pembangunan New Yogyakarta International Airport Kulon Progo. Pada lokasi tersebut terdapat tanah pasir lepas dan berpotensi likuefaksi hingga kedalaman 8m. Analisis yang dilakukan yaitu membandingkan nilai Standard Penetration Test (SPT) sebelum dan setelah perbaikan tanah dengan RIC. Hasil analisis menunjukkan bahwa terdapat kenaikan nilai SPT sebesar 10 – 12, sehingga dapat memehuni kriteria desain yang telah ditentukan untuk mitigasi likuefaksi.Kata kunci: perbaikan tanah, likuefaksi, Rapid Impact Compaction, SPT. ABSTRACTRapid Impact Compaction (RIC) is one of mechanical ground improvement technique that suitable for granular soil material. The principle of this method is repeatedly strike an impact plate on the ground surface using a hydraulic hammer. RIC can be implemented as an alternative for liquefaction mitigation. Some previous studies have stated that RIC can improve the soil to a depth of 6 m. The evaluation of effectiveness RIC to improving problematic soil was taken in New Yogyakarta International Airport project. At the project site, the soil condition is consist of loose sand and potential to be liquefied up to 8 m depth. The analysis has donne by comparing the SPT value before and after improving by RIC. The result of analysis gave an information that there is an increace SPT value of 10 – 12, so it can meet with the design criteria for mitigation of liquefaction.Keywords: ground improvement, liquifaction, Rapid Impact Compaction, SPT.

Evaluasi Perbaikan Tanah Menggunakan Rapid Impact Compaction pada Tanah Berpotensi Likuefaksi

ABSTRAKRapid Impact Compaction (RIC) merupakan salah satu metode perbaikan tanah secara mekanik untuk tanah granular. Prinsip dasar dari Rapid Impact Compaction yaitu menjatuhkan beban hammer dengan tinggi jatuh yang relatif rendah dengan kecepatan yang tinggi. RIC dapat dijadikan alternatif dalam mitigasi likuefaksi. Beberapa penelitian sebelumnya menyatakan bahwa RIC dapat memperbaiki tanah hingga kedalaman 6 m. Pada penelitian ini, evaluasi efektifitas perbaikan tanah menggunakan RIC dilakukan di lokasi Pembangunan New Yogyakarta International Airport Kulon Progo. Pada lokasi tersebut terdapat tanah pasir lepas dan berpotensi likuefaksi hingga kedalaman 8m. Analisis yang dilakukan yaitu membandingkan nilai Standard Penetration Test (SPT) sebelum dan setelah perbaikan tanah dengan RIC. Hasil analisis menunjukkan bahwa terdapat kenaikan nilai SPT sebesar 10 – 12, sehingga dapat memehuni kriteria desain yang telah ditentukan untuk mitigasi likuefaksi.Kata kunci: perbaikan tanah, likuefaksi, Rapid Impact Compaction, SPT. ABSTRACTRapid Impact Compaction (RIC) is one of mechanical ground improvement technique that suitable for granular soil material. The principle of this method is repeatedly strike an impact plate on the ground surface using a hydraulic hammer. RIC can be implemented as an alternative for liquefaction mitigation. Some previous studies have stated that RIC can improve the soil to a depth of 6 m. The evaluation of effectiveness RIC to improving problematic soil was taken in New Yogyakarta International Airport project. At the project site, the soil condition is consist of loose sand and potential to be liquefied up to 8 m depth. The analysis has donne by comparing the SPT value before and after improving by RIC. The result of analysis gave an information that there is an increace SPT value of 10 – 12, so it can meet with the design criteria for mitigation of liquefaction.Keywords: ground improvement, liquifaction, Rapid Impact Compaction, SPT.

Uji Pengaruh Energi Rapid Impact Compaction terhadap Tingkat Kepadatan Tanah Timbunan

Penelitian ini dimaksudkan untuk menganalisis pengaruh energi pemadatan metode Rapid Impact Compaction (RIC) terhadap karakteristik pemadatan pada tanah timbunan. Metode yang digunakan adalah model alat RIC hasil pengembangan di Laboratorium Mekanika Tanah Universitas Hasunuddin dimana alat ini di kendalikan secara elektro-mekanis. Proses pemadatan dilakukan dengan memvariasikan jumlah tumbukan untuk variasi energi pemadatan. Dimana berat beban penumbuk 70 kg dan tinggi jatuh 15 cm. Untuk uji elemen menggunakan mould berdiameter 15 cm dan tinggi 25 cm sedangkan uji model mengunakan bak uji berdiameter 80 cm dan tinggi 120 cm. Untuk menguji tingkat kepadatan menggunakan DCP Test, CBR Test dan Sandcone Test. Hasil pengujian mendapatkan adanya pegaruh energi pemadatan terhadap nilai CBR dan berat isi kering tanah. Hubungan antara perbandingan energi pemadatan RIC terhadap energi pemadatan standar proctor memenuhi persamaan ϒd RIC = 0,0915 (ESP) + 1,046. Dari grafik didapatkan titik perpotongan yang merupakan titik optimum energi RIC untuk mendapatkan kepadatan sesuai energi pemadatan proctor. Dalam pengujian ini didapatkan titik optimum energinya sebesar 2.01 ESP terhadap pemadatan standar proctor dan 3.32 ESP terhadap modified proctor. Pada pengujian pemadatan RIC model pada kumulatif jumlah tumbukan sebanyak 90 kali tanah tidak mengalami penurunan. Evaluasi kinerja hasil pemadatan RIC didapat nilai Relatif Compaction (Rc) sebesar 95 %.

Interpretation of CBR Test Results Based on the Rapid Impact Compaction Electro-Mechanic System Model

In order to understand the mechanical properties of the compaction results and to optimize the relevant energy design of the repeated Rapid Impact Compaction (RIC), a series of California Bearing Ratio (CBR) tests were performed on the compaction sample with RIC electro-mechanic system. In this laboratory test, samples were compacted at various RIC impact energy levels. A mass of different weight and various of falling height was used to compact the samples in a CBR cylindrical test. The mass was repeatedly dropped on the anvil plate with a frequency of 30-40 blows per minute. The compaction process carried out by varying number of blows from 5 to 35 for each compacted sample, and all compaction processes were controlled by electro-mechanic new development system. The test results represented that there was a variation of CBR value at the same RIC energy levels. The CBR values at the same energy level with the larger number of blow increased higher in lighter mass, whereas than the RIC energy level for larger masses with the smaller number of blows also occurred with the same trend to the result of relative compaction density test. This advantages that with a better understanding of RIC mechanisms and relevant energy designs, it is a new practical idea to improve compaction degree as well as CBR value on fill construction works with appropriate equipment and lower energy consumption.