Objektif kajian ini adalah untuk menunjukkan pembangunan kaedah berangka untuk menilai keboleharapan cerun tanah dan menentukan kebarangkalian permukaan gelonsoran genting. Fungsi prestasi dirumuskan menggunakan kaedah had keseimbangan Bishop mudah untuk mengira indeks keboleharapan. Indeks keboleharapan yang ditakrifkan oleh Hasofer dan Lind digunakan sebagai indeks ukuran keselamatan. Pencarian permukaan gelonsoran genting secara kebarangkaliannya yang berkaitan dengan indeks keboleharapan terendah dirumuskan sebagai masalah pengoptimuman.
Seterusnya pengoptimuman kelompok zarah digunakan untuk mengira indeks keboleharapan Hasofer dan Lind dan kebarangkalian permukaan kegagalan genting. Penggunaan algorithma ini ditunjukkan melalui tiga contoh berangka daripada kajian terdahulu. Keputusan menunjukkan bahawa kaedah yang dicadangkan berupaya untuk memberikan penyelesaian yang lebih baik bagi analisis keboleharapan cerun tanah berbanding dengan kaedah yang dilaporkan dalam kajian-kajian terdahulu.
Gempa bumi pada 30 September 2009, dengan kekuatan 7.6 MW yang melanda Bandar Padang, Padang Pariaman dan wilayah Sumatera Barat, Indonesia, telah mengorbankan lebih daripada 1200 orang. Ribuan buah rumah, bangunan dan infrastruktur lain telah mengalami kerosakan tahap ringan hingga teruk. Kajian ini bertujuan untuk melaporkan kesan gempa bumi Padang terhadap kerosakan bangunan dan tanah runtuh yang berlaku pada kawasan Bandar Padang, Padang Pariaman, Pariaman dan Agam. Kesan gempa bumi ini dianalisis berdasarkan data geologi, geoteknik dan impak geo-bencana yang telah dikumpulkan daripada berbagai sumber dan hasil kajian lapangan. Hasil kajian menunjukkan bahawa kerosakan di kawasan bandar Padang dan Padang Pariaman lebih disebabkan oleh kualiti bangunan yang tidak memenuhi piawaian bangunan dan pengaruh geologi kawasan, iaitu berlakunya amplifikasi tanah disebabkan oleh endapan aluvium yang tebal. Kerosakan teruk pada bangunan antara lainnya dikaitkan dengan kehadiran jalur-jalur sesar kecil atau ketakselanjaran pada lapisan bawah tanah. Beberapa kejadian tanah runtuh besar yang berlaku di Pariaman dan Agam adalah disebabkan oleh geologi kawasan, geomorfologi dan morfologi cerun yang curam. Kajian lanjut diperlukan bagi mengenal pasti dan menilai risiko bencana untuk persediaan menghadapi bencana gempa bumi di masa hadapan.
Environmental concerns have significantly influenced the construction industry regarding the identification and use of environmentally sustainable construction materials. In this context, enzymes (organic materials) have been introduced recently for ground improvement projects such as pavements and embankments. The present experimental study was carried out in order to evaluate the compressive strength of a sedimentary residual soil treated with three different types of enzymes, as assessed through a California bearing ratio (CBR) test. Controlled untreated and treated soil samples containing four dosages (the recommended dose and two, five and 10 times the recommended dose) were prepared, sealed and cured for four months. Following the curing period, samples were soaked in water for four days before the CBR tests were administered. These tests showed no improvement in the soil is compressive strength; in other words, samples prepared even at higher dosages did not exhibit any improvement. Nuclear magnetic resonance (NMR) spectroscopy tests were carried out on three enzymes in order to study the functional groups present in them. Furthermore, X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) tests were executed for untreated and treated soil samples to determine if any chemical reaction took place between the soil and the enzymes. Neither of the tests (XRD nor FESEM) revealed any change. In fact, the XRD patterns and FESEM images for untreated and treated soil samples were indistinguishable.
In this study, the performance of two types of nanocarbons (NCs), namely carbon nanotubes (CNTs) and carbon nanofibers (CNFs), on the three-dimensional shrinkage and swelling properties of three clayey soils were investigated. The specimens of soil mixed with clay with bentonite contents of 0, 10 and 20% by weight of dry soil. NC contents of 0.05, 0.075, 0.10 and 0.20% were chosen to investigate the influence of different NC types, CNTs and CNFs. All soil specimens were compacted under maximum dry unit weight and optimum water content conditions by using standard compaction tests. The physical and mechanical characteristics of the reinforced samples were then determined. These included the desiccation cracking area, used to determine the crack intensity factor (CIF), as well as the shrinkage and swelling. The CIF for the soil specimens without NCs were higher than the soil specimens with NC additives. These results show that NCs decrease the development of desiccation cracks on the surface of compacted samples. The shrinkage and swelling tests showed that the rate of volume changing of the compacted soil specimens reduced with the increasing of NCs.