On some uncertainties related to static liquefaction triggering assessments

Static liquefaction has been identified as the cause of several recent tailings storage facility (TSF) failures. Partially based on the investigations carried out, significant advances on the analysis of static liquefaction triggering have been made. This includes application of critical state-based models in a stress-deformation framework to identify if in situ conditions are approaching a level where triggering could occur. However, several important uncertainties remain. The current work investigates three of these uncertainties and their effect (both independently, and in conjunction) on the identification of static liquefaction triggering and slope failure: geostatic stress ratio K0, intermediate principal stress ratio, and principal stress angle from vertical. These uncertainties are examined through a series of numerical analyses of an idealised TSF. Various values of K0 are used to examine their effect on triggering, while different approaches to the potential effect of intermediate principal stress ratio and principal stress angle from vertical on instability are taken. This work shows that current state of knowledge in these areas is such that significant uncertainty seems unavoidable in attempting to identify exactly when a particular slope may undergo static liquefaction triggering. Experimental and in situ test programs that may be useful in reducing this uncertainty are outlined.

Pelatihan Pengujian In-Situ Tanah bagi laboran Muda Mekanika Tanah

In-situ test adalah salah satu metode pengujian geomekanika yang pelaksanaannya dilakukan langsung di lapangan, tanpa pengambilan percontoh untuk laboratorium. Rendahnya minat laboran dalam mendalami bidang mekanika tanah khususnya pengujian tanah baik di lapangan maupun di laboratorium. Hal ini di sebabkan oleh para laboran menganggab bahwa pengembangan keahlian dalam menggunakan peralatan pengujian dan pengolahan data mekanika tanah cukup sulit dan mahal. HIMATESI merupakan sebuah himpunan mahasiswa yang beranggotakan para peneliti muda, laboran muda atau mahasiswa tingkat akhir yang sedang melakukan penelitian dan pengujian mekanika tanah. Mitra menyadari perlu peningkatan pemahaman tentang pengujian In-Situ tanah. Namun disisi lain menjadi ketakutan tersendiri bagi mitra tentang penyelsaiaan permasalahan yang timbul dalam pengujian In-Situ tanah pada saat pelaksanaan dilapangan. Perguruan tinggi menjawab persoalan mitra dengan memberikan pengetahuan tentang pengujian In-Situ tanah dan pelatihan penggunaan peralatan pengujian In-Situ tanah serta trik-trik menhadapi permasalahan dalam pengujian In-Situ tanah pengujian In-Situ tanah secara gratis. Kegiatan Pengabdian masyarakat dalam bentuk pelatihan pengujian In-Situ Tanah bagi laboran mekanika tanah yang diadakan bertujuan untuk memberikan bekal informasi tentang tentang pengenalan dan penggunaan alat pengujian In-Situ seperti Dynamic Cone Penetrometer, alat Handbore dan alat Sandcone. Hasil pelatihan ini mampu meningkatkan pengetahuan peserta terhadap penggunaan alat pengujian In-situ tanah dan trik-trik dalam mengatasi permasalahan dilapangan terhadap penggunaan alat Insitu sehingga diharapkan para peserta dapat mengimplementasikan ilmu yang di dapat dalam pelaksanaan dilapangan nantinya.

In Situ Test Research on Friction Resistance of Self-Anchored Test Pile

The traditional static load test method has been considered as the most direct and reliable method to determine the bearing capacity of single pile, but it has some disadvantages, such as inconvenient operation, laborious test, high cost, and being time-consuming. In this paper, a new type of pile testing method, self-anchored pile testing method, was proposed, and the in situ test was carried out for the first time. This method allows the upper and lower piles to provide force to each other and does not occupy other construction spaces. It had the advantages of simple operation and being economical and practical. Based on the Q-w curve, axial force distribution curve, and hyperbolic function model of load transfer, this paper studied the evolution law of friction of self-anchored test pile and the load transfer process of self-anchored test pile. The results show that the load transfer process of self-anchored pile-soil interface can be divided into three stages: elastic, elastic-plastic, and limit state. The friction of the upper and lower piles starts from the bottom of each pile and then gradually increases. The soil around the upper and lower piles gradually undergoes nonlinear deformation and shear failure, and the pile soil reaches the yield state. By analyzing the hyperbolic function model of load transfer, it shows that the hyperbolic function model can be better applied to the self-anchored test pile, which has reference value for the selection of the function model of self-anchored test pile in the future.